Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
Warning:line 3124, column 23
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name LoopVectorize.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Analysis -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ASMParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/BinaryFormat -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitstream -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /include/llvm/CodeGen -I /include/llvm/CodeGen/PBQP -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Coroutines -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData/Coverage -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/CodeView -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/DWARF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/MSF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/PDB -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Demangle -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/JITLink -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/Orc -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenACC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenMP -I /include/llvm/CodeGen/GlobalISel -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IRReader -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/LTO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Linker -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC/MCParser -I /include/llvm/CodeGen/MIRParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Object -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Option -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Passes -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Scalar -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/Symbolize -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Target -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Utils -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Vectorize -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/IPO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libLLVM/../include -I /usr/src/gnu/usr.bin/clang/libLLVM/obj -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -D PIC -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -D_RET_PROTECTOR -ret-protector -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
1//===- LoopVectorize.cpp - A Loop Vectorizer ------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This is the LLVM loop vectorizer. This pass modifies 'vectorizable' loops
10// and generates target-independent LLVM-IR.
11// The vectorizer uses the TargetTransformInfo analysis to estimate the costs
12// of instructions in order to estimate the profitability of vectorization.
13//
14// The loop vectorizer combines consecutive loop iterations into a single
15// 'wide' iteration. After this transformation the index is incremented
16// by the SIMD vector width, and not by one.
17//
18// This pass has three parts:
19// 1. The main loop pass that drives the different parts.
20// 2. LoopVectorizationLegality - A unit that checks for the legality
21// of the vectorization.
22// 3. InnerLoopVectorizer - A unit that performs the actual
23// widening of instructions.
24// 4. LoopVectorizationCostModel - A unit that checks for the profitability
25// of vectorization. It decides on the optimal vector width, which
26// can be one, if vectorization is not profitable.
27//
28// There is a development effort going on to migrate loop vectorizer to the
29// VPlan infrastructure and to introduce outer loop vectorization support (see
30// docs/Proposal/VectorizationPlan.rst and
31// http://lists.llvm.org/pipermail/llvm-dev/2017-December/119523.html). For this
32// purpose, we temporarily introduced the VPlan-native vectorization path: an
33// alternative vectorization path that is natively implemented on top of the
34// VPlan infrastructure. See EnableVPlanNativePath for enabling.
35//
36//===----------------------------------------------------------------------===//
37//
38// The reduction-variable vectorization is based on the paper:
39// D. Nuzman and R. Henderson. Multi-platform Auto-vectorization.
40//
41// Variable uniformity checks are inspired by:
42// Karrenberg, R. and Hack, S. Whole Function Vectorization.
43//
44// The interleaved access vectorization is based on the paper:
45// Dorit Nuzman, Ira Rosen and Ayal Zaks. Auto-Vectorization of Interleaved
46// Data for SIMD
47//
48// Other ideas/concepts are from:
49// A. Zaks and D. Nuzman. Autovectorization in GCC-two years later.
50//
51// S. Maleki, Y. Gao, M. Garzaran, T. Wong and D. Padua. An Evaluation of
52// Vectorizing Compilers.
53//
54//===----------------------------------------------------------------------===//
55
56#include "llvm/Transforms/Vectorize/LoopVectorize.h"
57#include "LoopVectorizationPlanner.h"
58#include "VPRecipeBuilder.h"
59#include "VPlan.h"
60#include "VPlanHCFGBuilder.h"
61#include "VPlanPredicator.h"
62#include "VPlanTransforms.h"
63#include "llvm/ADT/APInt.h"
64#include "llvm/ADT/ArrayRef.h"
65#include "llvm/ADT/DenseMap.h"
66#include "llvm/ADT/DenseMapInfo.h"
67#include "llvm/ADT/Hashing.h"
68#include "llvm/ADT/MapVector.h"
69#include "llvm/ADT/None.h"
70#include "llvm/ADT/Optional.h"
71#include "llvm/ADT/STLExtras.h"
72#include "llvm/ADT/SmallPtrSet.h"
73#include "llvm/ADT/SmallSet.h"
74#include "llvm/ADT/SmallVector.h"
75#include "llvm/ADT/Statistic.h"
76#include "llvm/ADT/StringRef.h"
77#include "llvm/ADT/Twine.h"
78#include "llvm/ADT/iterator_range.h"
79#include "llvm/Analysis/AssumptionCache.h"
80#include "llvm/Analysis/BasicAliasAnalysis.h"
81#include "llvm/Analysis/BlockFrequencyInfo.h"
82#include "llvm/Analysis/CFG.h"
83#include "llvm/Analysis/CodeMetrics.h"
84#include "llvm/Analysis/DemandedBits.h"
85#include "llvm/Analysis/GlobalsModRef.h"
86#include "llvm/Analysis/LoopAccessAnalysis.h"
87#include "llvm/Analysis/LoopAnalysisManager.h"
88#include "llvm/Analysis/LoopInfo.h"
89#include "llvm/Analysis/LoopIterator.h"
90#include "llvm/Analysis/MemorySSA.h"
91#include "llvm/Analysis/OptimizationRemarkEmitter.h"
92#include "llvm/Analysis/ProfileSummaryInfo.h"
93#include "llvm/Analysis/ScalarEvolution.h"
94#include "llvm/Analysis/ScalarEvolutionExpressions.h"
95#include "llvm/Analysis/TargetLibraryInfo.h"
96#include "llvm/Analysis/TargetTransformInfo.h"
97#include "llvm/Analysis/VectorUtils.h"
98#include "llvm/IR/Attributes.h"
99#include "llvm/IR/BasicBlock.h"
100#include "llvm/IR/CFG.h"
101#include "llvm/IR/Constant.h"
102#include "llvm/IR/Constants.h"
103#include "llvm/IR/DataLayout.h"
104#include "llvm/IR/DebugInfoMetadata.h"
105#include "llvm/IR/DebugLoc.h"
106#include "llvm/IR/DerivedTypes.h"
107#include "llvm/IR/DiagnosticInfo.h"
108#include "llvm/IR/Dominators.h"
109#include "llvm/IR/Function.h"
110#include "llvm/IR/IRBuilder.h"
111#include "llvm/IR/InstrTypes.h"
112#include "llvm/IR/Instruction.h"
113#include "llvm/IR/Instructions.h"
114#include "llvm/IR/IntrinsicInst.h"
115#include "llvm/IR/Intrinsics.h"
116#include "llvm/IR/LLVMContext.h"
117#include "llvm/IR/Metadata.h"
118#include "llvm/IR/Module.h"
119#include "llvm/IR/Operator.h"
120#include "llvm/IR/PatternMatch.h"
121#include "llvm/IR/Type.h"
122#include "llvm/IR/Use.h"
123#include "llvm/IR/User.h"
124#include "llvm/IR/Value.h"
125#include "llvm/IR/ValueHandle.h"
126#include "llvm/IR/Verifier.h"
127#include "llvm/InitializePasses.h"
128#include "llvm/Pass.h"
129#include "llvm/Support/Casting.h"
130#include "llvm/Support/CommandLine.h"
131#include "llvm/Support/Compiler.h"
132#include "llvm/Support/Debug.h"
133#include "llvm/Support/ErrorHandling.h"
134#include "llvm/Support/InstructionCost.h"
135#include "llvm/Support/MathExtras.h"
136#include "llvm/Support/raw_ostream.h"
137#include "llvm/Transforms/Utils/BasicBlockUtils.h"
138#include "llvm/Transforms/Utils/InjectTLIMappings.h"
139#include "llvm/Transforms/Utils/LoopSimplify.h"
140#include "llvm/Transforms/Utils/LoopUtils.h"
141#include "llvm/Transforms/Utils/LoopVersioning.h"
142#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
143#include "llvm/Transforms/Utils/SizeOpts.h"
144#include "llvm/Transforms/Vectorize/LoopVectorizationLegality.h"
145#include <algorithm>
146#include <cassert>
147#include <cstdint>
148#include <cstdlib>
149#include <functional>
150#include <iterator>
151#include <limits>
152#include <memory>
153#include <string>
154#include <tuple>
155#include <utility>
156
157using namespace llvm;
158
159#define LV_NAME"loop-vectorize" "loop-vectorize"
160#define DEBUG_TYPE"loop-vectorize" LV_NAME"loop-vectorize"
161
162#ifndef NDEBUG1
163const char VerboseDebug[] = DEBUG_TYPE"loop-vectorize" "-verbose";
164#endif
165
166/// @{
167/// Metadata attribute names
168const char LLVMLoopVectorizeFollowupAll[] = "llvm.loop.vectorize.followup_all";
169const char LLVMLoopVectorizeFollowupVectorized[] =
170 "llvm.loop.vectorize.followup_vectorized";
171const char LLVMLoopVectorizeFollowupEpilogue[] =
172 "llvm.loop.vectorize.followup_epilogue";
173/// @}
174
175STATISTIC(LoopsVectorized, "Number of loops vectorized")static llvm::Statistic LoopsVectorized = {"loop-vectorize", "LoopsVectorized"
, "Number of loops vectorized"}
;
176STATISTIC(LoopsAnalyzed, "Number of loops analyzed for vectorization")static llvm::Statistic LoopsAnalyzed = {"loop-vectorize", "LoopsAnalyzed"
, "Number of loops analyzed for vectorization"}
;
177STATISTIC(LoopsEpilogueVectorized, "Number of epilogues vectorized")static llvm::Statistic LoopsEpilogueVectorized = {"loop-vectorize"
, "LoopsEpilogueVectorized", "Number of epilogues vectorized"
}
;
178
179static cl::opt<bool> EnableEpilogueVectorization(
180 "enable-epilogue-vectorization", cl::init(true), cl::Hidden,
181 cl::desc("Enable vectorization of epilogue loops."));
182
183static cl::opt<unsigned> EpilogueVectorizationForceVF(
184 "epilogue-vectorization-force-VF", cl::init(1), cl::Hidden,
185 cl::desc("When epilogue vectorization is enabled, and a value greater than "
186 "1 is specified, forces the given VF for all applicable epilogue "
187 "loops."));
188
189static cl::opt<unsigned> EpilogueVectorizationMinVF(
190 "epilogue-vectorization-minimum-VF", cl::init(16), cl::Hidden,
191 cl::desc("Only loops with vectorization factor equal to or larger than "
192 "the specified value are considered for epilogue vectorization."));
193
194/// Loops with a known constant trip count below this number are vectorized only
195/// if no scalar iteration overheads are incurred.
196static cl::opt<unsigned> TinyTripCountVectorThreshold(
197 "vectorizer-min-trip-count", cl::init(16), cl::Hidden,
198 cl::desc("Loops with a constant trip count that is smaller than this "
199 "value are vectorized only if no scalar iteration overheads "
200 "are incurred."));
201
202static cl::opt<unsigned> PragmaVectorizeMemoryCheckThreshold(
203 "pragma-vectorize-memory-check-threshold", cl::init(128), cl::Hidden,
204 cl::desc("The maximum allowed number of runtime memory checks with a "
205 "vectorize(enable) pragma."));
206
207// Option prefer-predicate-over-epilogue indicates that an epilogue is undesired,
208// that predication is preferred, and this lists all options. I.e., the
209// vectorizer will try to fold the tail-loop (epilogue) into the vector body
210// and predicate the instructions accordingly. If tail-folding fails, there are
211// different fallback strategies depending on these values:
212namespace PreferPredicateTy {
213 enum Option {
214 ScalarEpilogue = 0,
215 PredicateElseScalarEpilogue,
216 PredicateOrDontVectorize
217 };
218} // namespace PreferPredicateTy
219
220static cl::opt<PreferPredicateTy::Option> PreferPredicateOverEpilogue(
221 "prefer-predicate-over-epilogue",
222 cl::init(PreferPredicateTy::ScalarEpilogue),
223 cl::Hidden,
224 cl::desc("Tail-folding and predication preferences over creating a scalar "
225 "epilogue loop."),
226 cl::values(clEnumValN(PreferPredicateTy::ScalarEpilogue,llvm::cl::OptionEnumValue { "scalar-epilogue", int(PreferPredicateTy
::ScalarEpilogue), "Don't tail-predicate loops, create scalar epilogue"
}
227 "scalar-epilogue",llvm::cl::OptionEnumValue { "scalar-epilogue", int(PreferPredicateTy
::ScalarEpilogue), "Don't tail-predicate loops, create scalar epilogue"
}
228 "Don't tail-predicate loops, create scalar epilogue")llvm::cl::OptionEnumValue { "scalar-epilogue", int(PreferPredicateTy
::ScalarEpilogue), "Don't tail-predicate loops, create scalar epilogue"
}
,
229 clEnumValN(PreferPredicateTy::PredicateElseScalarEpilogue,llvm::cl::OptionEnumValue { "predicate-else-scalar-epilogue",
int(PreferPredicateTy::PredicateElseScalarEpilogue), "prefer tail-folding, create scalar epilogue if tail "
"folding fails." }
230 "predicate-else-scalar-epilogue",llvm::cl::OptionEnumValue { "predicate-else-scalar-epilogue",
int(PreferPredicateTy::PredicateElseScalarEpilogue), "prefer tail-folding, create scalar epilogue if tail "
"folding fails." }
231 "prefer tail-folding, create scalar epilogue if tail "llvm::cl::OptionEnumValue { "predicate-else-scalar-epilogue",
int(PreferPredicateTy::PredicateElseScalarEpilogue), "prefer tail-folding, create scalar epilogue if tail "
"folding fails." }
232 "folding fails.")llvm::cl::OptionEnumValue { "predicate-else-scalar-epilogue",
int(PreferPredicateTy::PredicateElseScalarEpilogue), "prefer tail-folding, create scalar epilogue if tail "
"folding fails." }
,
233 clEnumValN(PreferPredicateTy::PredicateOrDontVectorize,llvm::cl::OptionEnumValue { "predicate-dont-vectorize", int(PreferPredicateTy
::PredicateOrDontVectorize), "prefers tail-folding, don't attempt vectorization if "
"tail-folding fails." }
234 "predicate-dont-vectorize",llvm::cl::OptionEnumValue { "predicate-dont-vectorize", int(PreferPredicateTy
::PredicateOrDontVectorize), "prefers tail-folding, don't attempt vectorization if "
"tail-folding fails." }
235 "prefers tail-folding, don't attempt vectorization if "llvm::cl::OptionEnumValue { "predicate-dont-vectorize", int(PreferPredicateTy
::PredicateOrDontVectorize), "prefers tail-folding, don't attempt vectorization if "
"tail-folding fails." }
236 "tail-folding fails.")llvm::cl::OptionEnumValue { "predicate-dont-vectorize", int(PreferPredicateTy
::PredicateOrDontVectorize), "prefers tail-folding, don't attempt vectorization if "
"tail-folding fails." }
));
237
238static cl::opt<bool> MaximizeBandwidth(
239 "vectorizer-maximize-bandwidth", cl::init(false), cl::Hidden,
240 cl::desc("Maximize bandwidth when selecting vectorization factor which "
241 "will be determined by the smallest type in loop."));
242
243static cl::opt<bool> EnableInterleavedMemAccesses(
244 "enable-interleaved-mem-accesses", cl::init(false), cl::Hidden,
245 cl::desc("Enable vectorization on interleaved memory accesses in a loop"));
246
247/// An interleave-group may need masking if it resides in a block that needs
248/// predication, or in order to mask away gaps.
249static cl::opt<bool> EnableMaskedInterleavedMemAccesses(
250 "enable-masked-interleaved-mem-accesses", cl::init(false), cl::Hidden,
251 cl::desc("Enable vectorization on masked interleaved memory accesses in a loop"));
252
253static cl::opt<unsigned> TinyTripCountInterleaveThreshold(
254 "tiny-trip-count-interleave-threshold", cl::init(128), cl::Hidden,
255 cl::desc("We don't interleave loops with a estimated constant trip count "
256 "below this number"));
257
258static cl::opt<unsigned> ForceTargetNumScalarRegs(
259 "force-target-num-scalar-regs", cl::init(0), cl::Hidden,
260 cl::desc("A flag that overrides the target's number of scalar registers."));
261
262static cl::opt<unsigned> ForceTargetNumVectorRegs(
263 "force-target-num-vector-regs", cl::init(0), cl::Hidden,
264 cl::desc("A flag that overrides the target's number of vector registers."));
265
266static cl::opt<unsigned> ForceTargetMaxScalarInterleaveFactor(
267 "force-target-max-scalar-interleave", cl::init(0), cl::Hidden,
268 cl::desc("A flag that overrides the target's max interleave factor for "
269 "scalar loops."));
270
271static cl::opt<unsigned> ForceTargetMaxVectorInterleaveFactor(
272 "force-target-max-vector-interleave", cl::init(0), cl::Hidden,
273 cl::desc("A flag that overrides the target's max interleave factor for "
274 "vectorized loops."));
275
276static cl::opt<unsigned> ForceTargetInstructionCost(
277 "force-target-instruction-cost", cl::init(0), cl::Hidden,
278 cl::desc("A flag that overrides the target's expected cost for "
279 "an instruction to a single constant value. Mostly "
280 "useful for getting consistent testing."));
281
282static cl::opt<bool> ForceTargetSupportsScalableVectors(
283 "force-target-supports-scalable-vectors", cl::init(false), cl::Hidden,
284 cl::desc(
285 "Pretend that scalable vectors are supported, even if the target does "
286 "not support them. This flag should only be used for testing."));
287
288static cl::opt<unsigned> SmallLoopCost(
289 "small-loop-cost", cl::init(20), cl::Hidden,
290 cl::desc(
291 "The cost of a loop that is considered 'small' by the interleaver."));
292
293static cl::opt<bool> LoopVectorizeWithBlockFrequency(
294 "loop-vectorize-with-block-frequency", cl::init(true), cl::Hidden,
295 cl::desc("Enable the use of the block frequency analysis to access PGO "
296 "heuristics minimizing code growth in cold regions and being more "
297 "aggressive in hot regions."));
298
299// Runtime interleave loops for load/store throughput.
300static cl::opt<bool> EnableLoadStoreRuntimeInterleave(
301 "enable-loadstore-runtime-interleave", cl::init(true), cl::Hidden,
302 cl::desc(
303 "Enable runtime interleaving until load/store ports are saturated"));
304
305/// Interleave small loops with scalar reductions.
306static cl::opt<bool> InterleaveSmallLoopScalarReduction(
307 "interleave-small-loop-scalar-reduction", cl::init(false), cl::Hidden,
308 cl::desc("Enable interleaving for loops with small iteration counts that "
309 "contain scalar reductions to expose ILP."));
310
311/// The number of stores in a loop that are allowed to need predication.
312static cl::opt<unsigned> NumberOfStoresToPredicate(
313 "vectorize-num-stores-pred", cl::init(1), cl::Hidden,
314 cl::desc("Max number of stores to be predicated behind an if."));
315
316static cl::opt<bool> EnableIndVarRegisterHeur(
317 "enable-ind-var-reg-heur", cl::init(true), cl::Hidden,
318 cl::desc("Count the induction variable only once when interleaving"));
319
320static cl::opt<bool> EnableCondStoresVectorization(
321 "enable-cond-stores-vec", cl::init(true), cl::Hidden,
322 cl::desc("Enable if predication of stores during vectorization."));
323
324static cl::opt<unsigned> MaxNestedScalarReductionIC(
325 "max-nested-scalar-reduction-interleave", cl::init(2), cl::Hidden,
326 cl::desc("The maximum interleave count to use when interleaving a scalar "
327 "reduction in a nested loop."));
328
329static cl::opt<bool>
330 PreferInLoopReductions("prefer-inloop-reductions", cl::init(false),
331 cl::Hidden,
332 cl::desc("Prefer in-loop vector reductions, "
333 "overriding the targets preference."));
334
335cl::opt<bool> EnableStrictReductions(
336 "enable-strict-reductions", cl::init(false), cl::Hidden,
337 cl::desc("Enable the vectorisation of loops with in-order (strict) "
338 "FP reductions"));
339
340static cl::opt<bool> PreferPredicatedReductionSelect(
341 "prefer-predicated-reduction-select", cl::init(false), cl::Hidden,
342 cl::desc(
343 "Prefer predicating a reduction operation over an after loop select."));
344
345cl::opt<bool> EnableVPlanNativePath(
346 "enable-vplan-native-path", cl::init(false), cl::Hidden,
347 cl::desc("Enable VPlan-native vectorization path with "
348 "support for outer loop vectorization."));
349
350// FIXME: Remove this switch once we have divergence analysis. Currently we
351// assume divergent non-backedge branches when this switch is true.
352cl::opt<bool> EnableVPlanPredication(
353 "enable-vplan-predication", cl::init(false), cl::Hidden,
354 cl::desc("Enable VPlan-native vectorization path predicator with "
355 "support for outer loop vectorization."));
356
357// This flag enables the stress testing of the VPlan H-CFG construction in the
358// VPlan-native vectorization path. It must be used in conjuction with
359// -enable-vplan-native-path. -vplan-verify-hcfg can also be used to enable the
360// verification of the H-CFGs built.
361static cl::opt<bool> VPlanBuildStressTest(
362 "vplan-build-stress-test", cl::init(false), cl::Hidden,
363 cl::desc(
364 "Build VPlan for every supported loop nest in the function and bail "
365 "out right after the build (stress test the VPlan H-CFG construction "
366 "in the VPlan-native vectorization path)."));
367
368cl::opt<bool> llvm::EnableLoopInterleaving(
369 "interleave-loops", cl::init(true), cl::Hidden,
370 cl::desc("Enable loop interleaving in Loop vectorization passes"));
371cl::opt<bool> llvm::EnableLoopVectorization(
372 "vectorize-loops", cl::init(true), cl::Hidden,
373 cl::desc("Run the Loop vectorization passes"));
374
375cl::opt<bool> PrintVPlansInDotFormat(
376 "vplan-print-in-dot-format", cl::init(false), cl::Hidden,
377 cl::desc("Use dot format instead of plain text when dumping VPlans"));
378
379/// A helper function that returns true if the given type is irregular. The
380/// type is irregular if its allocated size doesn't equal the store size of an
381/// element of the corresponding vector type.
382static bool hasIrregularType(Type *Ty, const DataLayout &DL) {
383 // Determine if an array of N elements of type Ty is "bitcast compatible"
384 // with a <N x Ty> vector.
385 // This is only true if there is no padding between the array elements.
386 return DL.getTypeAllocSizeInBits(Ty) != DL.getTypeSizeInBits(Ty);
387}
388
389/// A helper function that returns the reciprocal of the block probability of
390/// predicated blocks. If we return X, we are assuming the predicated block
391/// will execute once for every X iterations of the loop header.
392///
393/// TODO: We should use actual block probability here, if available. Currently,
394/// we always assume predicated blocks have a 50% chance of executing.
395static unsigned getReciprocalPredBlockProb() { return 2; }
396
397/// A helper function that returns an integer or floating-point constant with
398/// value C.
399static Constant *getSignedIntOrFpConstant(Type *Ty, int64_t C) {
400 return Ty->isIntegerTy() ? ConstantInt::getSigned(Ty, C)
401 : ConstantFP::get(Ty, C);
402}
403
404/// Returns "best known" trip count for the specified loop \p L as defined by
405/// the following procedure:
406/// 1) Returns exact trip count if it is known.
407/// 2) Returns expected trip count according to profile data if any.
408/// 3) Returns upper bound estimate if it is known.
409/// 4) Returns None if all of the above failed.
410static Optional<unsigned> getSmallBestKnownTC(ScalarEvolution &SE, Loop *L) {
411 // Check if exact trip count is known.
412 if (unsigned ExpectedTC = SE.getSmallConstantTripCount(L))
413 return ExpectedTC;
414
415 // Check if there is an expected trip count available from profile data.
416 if (LoopVectorizeWithBlockFrequency)
417 if (auto EstimatedTC = getLoopEstimatedTripCount(L))
418 return EstimatedTC;
419
420 // Check if upper bound estimate is known.
421 if (unsigned ExpectedTC = SE.getSmallConstantMaxTripCount(L))
422 return ExpectedTC;
423
424 return None;
425}
426
427// Forward declare GeneratedRTChecks.
428class GeneratedRTChecks;
429
430namespace llvm {
431
432/// InnerLoopVectorizer vectorizes loops which contain only one basic
433/// block to a specified vectorization factor (VF).
434/// This class performs the widening of scalars into vectors, or multiple
435/// scalars. This class also implements the following features:
436/// * It inserts an epilogue loop for handling loops that don't have iteration
437/// counts that are known to be a multiple of the vectorization factor.
438/// * It handles the code generation for reduction variables.
439/// * Scalarization (implementation using scalars) of un-vectorizable
440/// instructions.
441/// InnerLoopVectorizer does not perform any vectorization-legality
442/// checks, and relies on the caller to check for the different legality
443/// aspects. The InnerLoopVectorizer relies on the
444/// LoopVectorizationLegality class to provide information about the induction
445/// and reduction variables that were found to a given vectorization factor.
446class InnerLoopVectorizer {
447public:
448 InnerLoopVectorizer(Loop *OrigLoop, PredicatedScalarEvolution &PSE,
449 LoopInfo *LI, DominatorTree *DT,
450 const TargetLibraryInfo *TLI,
451 const TargetTransformInfo *TTI, AssumptionCache *AC,
452 OptimizationRemarkEmitter *ORE, ElementCount VecWidth,
453 unsigned UnrollFactor, LoopVectorizationLegality *LVL,
454 LoopVectorizationCostModel *CM, BlockFrequencyInfo *BFI,
455 ProfileSummaryInfo *PSI, GeneratedRTChecks &RTChecks)
456 : OrigLoop(OrigLoop), PSE(PSE), LI(LI), DT(DT), TLI(TLI), TTI(TTI),
457 AC(AC), ORE(ORE), VF(VecWidth), UF(UnrollFactor),
458 Builder(PSE.getSE()->getContext()), Legal(LVL), Cost(CM), BFI(BFI),
459 PSI(PSI), RTChecks(RTChecks) {
460 // Query this against the original loop and save it here because the profile
461 // of the original loop header may change as the transformation happens.
462 OptForSizeBasedOnProfile = llvm::shouldOptimizeForSize(
463 OrigLoop->getHeader(), PSI, BFI, PGSOQueryType::IRPass);
464 }
465
466 virtual ~InnerLoopVectorizer() = default;
467
468 /// Create a new empty loop that will contain vectorized instructions later
469 /// on, while the old loop will be used as the scalar remainder. Control flow
470 /// is generated around the vectorized (and scalar epilogue) loops consisting
471 /// of various checks and bypasses. Return the pre-header block of the new
472 /// loop.
473 /// In the case of epilogue vectorization, this function is overriden to
474 /// handle the more complex control flow around the loops.
475 virtual BasicBlock *createVectorizedLoopSkeleton();
476
477 /// Widen a single instruction within the innermost loop.
478 void widenInstruction(Instruction &I, VPValue *Def, VPUser &Operands,
479 VPTransformState &State);
480
481 /// Widen a single call instruction within the innermost loop.
482 void widenCallInstruction(CallInst &I, VPValue *Def, VPUser &ArgOperands,
483 VPTransformState &State);
484
485 /// Widen a single select instruction within the innermost loop.
486 void widenSelectInstruction(SelectInst &I, VPValue *VPDef, VPUser &Operands,
487 bool InvariantCond, VPTransformState &State);
488
489 /// Fix the vectorized code, taking care of header phi's, live-outs, and more.
490 void fixVectorizedLoop(VPTransformState &State);
491
492 // Return true if any runtime check is added.
493 bool areSafetyChecksAdded() { return AddedSafetyChecks; }
494
495 /// A type for vectorized values in the new loop. Each value from the
496 /// original loop, when vectorized, is represented by UF vector values in the
497 /// new unrolled loop, where UF is the unroll factor.
498 using VectorParts = SmallVector<Value *, 2>;
499
500 /// Vectorize a single GetElementPtrInst based on information gathered and
501 /// decisions taken during planning.
502 void widenGEP(GetElementPtrInst *GEP, VPValue *VPDef, VPUser &Indices,
503 unsigned UF, ElementCount VF, bool IsPtrLoopInvariant,
504 SmallBitVector &IsIndexLoopInvariant, VPTransformState &State);
505
506 /// Vectorize a single first-order recurrence or pointer induction PHINode in
507 /// a block. This method handles the induction variable canonicalization. It
508 /// supports both VF = 1 for unrolled loops and arbitrary length vectors.
509 void widenPHIInstruction(Instruction *PN, VPWidenPHIRecipe *PhiR,
510 VPTransformState &State);
511
512 /// A helper function to scalarize a single Instruction in the innermost loop.
513 /// Generates a sequence of scalar instances for each lane between \p MinLane
514 /// and \p MaxLane, times each part between \p MinPart and \p MaxPart,
515 /// inclusive. Uses the VPValue operands from \p Operands instead of \p
516 /// Instr's operands.
517 void scalarizeInstruction(Instruction *Instr, VPValue *Def, VPUser &Operands,
518 const VPIteration &Instance, bool IfPredicateInstr,
519 VPTransformState &State);
520
521 /// Widen an integer or floating-point induction variable \p IV. If \p Trunc
522 /// is provided, the integer induction variable will first be truncated to
523 /// the corresponding type.
524 void widenIntOrFpInduction(PHINode *IV, Value *Start, TruncInst *Trunc,
525 VPValue *Def, VPValue *CastDef,
526 VPTransformState &State);
527
528 /// Construct the vector value of a scalarized value \p V one lane at a time.
529 void packScalarIntoVectorValue(VPValue *Def, const VPIteration &Instance,
530 VPTransformState &State);
531
532 /// Try to vectorize interleaved access group \p Group with the base address
533 /// given in \p Addr, optionally masking the vector operations if \p
534 /// BlockInMask is non-null. Use \p State to translate given VPValues to IR
535 /// values in the vectorized loop.
536 void vectorizeInterleaveGroup(const InterleaveGroup<Instruction> *Group,
537 ArrayRef<VPValue *> VPDefs,
538 VPTransformState &State, VPValue *Addr,
539 ArrayRef<VPValue *> StoredValues,
540 VPValue *BlockInMask = nullptr);
541
542 /// Vectorize Load and Store instructions with the base address given in \p
543 /// Addr, optionally masking the vector operations if \p BlockInMask is
544 /// non-null. Use \p State to translate given VPValues to IR values in the
545 /// vectorized loop.
546 void vectorizeMemoryInstruction(Instruction *Instr, VPTransformState &State,
547 VPValue *Def, VPValue *Addr,
548 VPValue *StoredValue, VPValue *BlockInMask);
549
550 /// Set the debug location in the builder \p Ptr using the debug location in
551 /// \p V. If \p Ptr is None then it uses the class member's Builder.
552 void setDebugLocFromInst(const Value *V,
553 Optional<IRBuilder<> *> CustomBuilder = None);
554
555 /// Fix the non-induction PHIs in the OrigPHIsToFix vector.
556 void fixNonInductionPHIs(VPTransformState &State);
557
558 /// Returns true if the reordering of FP operations is not allowed, but we are
559 /// able to vectorize with strict in-order reductions for the given RdxDesc.
560 bool useOrderedReductions(RecurrenceDescriptor &RdxDesc);
561
562 /// Create a broadcast instruction. This method generates a broadcast
563 /// instruction (shuffle) for loop invariant values and for the induction
564 /// value. If this is the induction variable then we extend it to N, N+1, ...
565 /// this is needed because each iteration in the loop corresponds to a SIMD
566 /// element.
567 virtual Value *getBroadcastInstrs(Value *V);
568
569protected:
570 friend class LoopVectorizationPlanner;
571
572 /// A small list of PHINodes.
573 using PhiVector = SmallVector<PHINode *, 4>;
574
575 /// A type for scalarized values in the new loop. Each value from the
576 /// original loop, when scalarized, is represented by UF x VF scalar values
577 /// in the new unrolled loop, where UF is the unroll factor and VF is the
578 /// vectorization factor.
579 using ScalarParts = SmallVector<SmallVector<Value *, 4>, 2>;
580
581 /// Set up the values of the IVs correctly when exiting the vector loop.
582 void fixupIVUsers(PHINode *OrigPhi, const InductionDescriptor &II,
583 Value *CountRoundDown, Value *EndValue,
584 BasicBlock *MiddleBlock);
585
586 /// Create a new induction variable inside L.
587 PHINode *createInductionVariable(Loop *L, Value *Start, Value *End,
588 Value *Step, Instruction *DL);
589
590 /// Handle all cross-iteration phis in the header.
591 void fixCrossIterationPHIs(VPTransformState &State);
592
593 /// Fix a first-order recurrence. This is the second phase of vectorizing
594 /// this phi node.
595 void fixFirstOrderRecurrence(VPWidenPHIRecipe *PhiR, VPTransformState &State);
596
597 /// Fix a reduction cross-iteration phi. This is the second phase of
598 /// vectorizing this phi node.
599 void fixReduction(VPReductionPHIRecipe *Phi, VPTransformState &State);
600
601 /// Clear NSW/NUW flags from reduction instructions if necessary.
602 void clearReductionWrapFlags(const RecurrenceDescriptor &RdxDesc,
603 VPTransformState &State);
604
605 /// Fixup the LCSSA phi nodes in the unique exit block. This simply
606 /// means we need to add the appropriate incoming value from the middle
607 /// block as exiting edges from the scalar epilogue loop (if present) are
608 /// already in place, and we exit the vector loop exclusively to the middle
609 /// block.
610 void fixLCSSAPHIs(VPTransformState &State);
611
612 /// Iteratively sink the scalarized operands of a predicated instruction into
613 /// the block that was created for it.
614 void sinkScalarOperands(Instruction *PredInst);
615
616 /// Shrinks vector element sizes to the smallest bitwidth they can be legally
617 /// represented as.
618 void truncateToMinimalBitwidths(VPTransformState &State);
619
620 /// This function adds
621 /// (StartIdx * Step, (StartIdx + 1) * Step, (StartIdx + 2) * Step, ...)
622 /// to each vector element of Val. The sequence starts at StartIndex.
623 /// \p Opcode is relevant for FP induction variable.
624 virtual Value *getStepVector(Value *Val, int StartIdx, Value *Step,
625 Instruction::BinaryOps Opcode =
626 Instruction::BinaryOpsEnd);
627
628 /// Compute scalar induction steps. \p ScalarIV is the scalar induction
629 /// variable on which to base the steps, \p Step is the size of the step, and
630 /// \p EntryVal is the value from the original loop that maps to the steps.
631 /// Note that \p EntryVal doesn't have to be an induction variable - it
632 /// can also be a truncate instruction.
633 void buildScalarSteps(Value *ScalarIV, Value *Step, Instruction *EntryVal,
634 const InductionDescriptor &ID, VPValue *Def,
635 VPValue *CastDef, VPTransformState &State);
636
637 /// Create a vector induction phi node based on an existing scalar one. \p
638 /// EntryVal is the value from the original loop that maps to the vector phi
639 /// node, and \p Step is the loop-invariant step. If \p EntryVal is a
640 /// truncate instruction, instead of widening the original IV, we widen a
641 /// version of the IV truncated to \p EntryVal's type.
642 void createVectorIntOrFpInductionPHI(const InductionDescriptor &II,
643 Value *Step, Value *Start,
644 Instruction *EntryVal, VPValue *Def,
645 VPValue *CastDef,
646 VPTransformState &State);
647
648 /// Returns true if an instruction \p I should be scalarized instead of
649 /// vectorized for the chosen vectorization factor.
650 bool shouldScalarizeInstruction(Instruction *I) const;
651
652 /// Returns true if we should generate a scalar version of \p IV.
653 bool needsScalarInduction(Instruction *IV) const;
654
655 /// If there is a cast involved in the induction variable \p ID, which should
656 /// be ignored in the vectorized loop body, this function records the
657 /// VectorLoopValue of the respective Phi also as the VectorLoopValue of the
658 /// cast. We had already proved that the casted Phi is equal to the uncasted
659 /// Phi in the vectorized loop (under a runtime guard), and therefore
660 /// there is no need to vectorize the cast - the same value can be used in the
661 /// vector loop for both the Phi and the cast.
662 /// If \p VectorLoopValue is a scalarized value, \p Lane is also specified,
663 /// Otherwise, \p VectorLoopValue is a widened/vectorized value.
664 ///
665 /// \p EntryVal is the value from the original loop that maps to the vector
666 /// phi node and is used to distinguish what is the IV currently being
667 /// processed - original one (if \p EntryVal is a phi corresponding to the
668 /// original IV) or the "newly-created" one based on the proof mentioned above
669 /// (see also buildScalarSteps() and createVectorIntOrFPInductionPHI()). In the
670 /// latter case \p EntryVal is a TruncInst and we must not record anything for
671 /// that IV, but it's error-prone to expect callers of this routine to care
672 /// about that, hence this explicit parameter.
673 void recordVectorLoopValueForInductionCast(
674 const InductionDescriptor &ID, const Instruction *EntryVal,
675 Value *VectorLoopValue, VPValue *CastDef, VPTransformState &State,
676 unsigned Part, unsigned Lane = UINT_MAX(2147483647 *2U +1U));
677
678 /// Generate a shuffle sequence that will reverse the vector Vec.
679 virtual Value *reverseVector(Value *Vec);
680
681 /// Returns (and creates if needed) the original loop trip count.
682 Value *getOrCreateTripCount(Loop *NewLoop);
683
684 /// Returns (and creates if needed) the trip count of the widened loop.
685 Value *getOrCreateVectorTripCount(Loop *NewLoop);
686
687 /// Returns a bitcasted value to the requested vector type.
688 /// Also handles bitcasts of vector<float> <-> vector<pointer> types.
689 Value *createBitOrPointerCast(Value *V, VectorType *DstVTy,
690 const DataLayout &DL);
691
692 /// Emit a bypass check to see if the vector trip count is zero, including if
693 /// it overflows.
694 void emitMinimumIterationCountCheck(Loop *L, BasicBlock *Bypass);
695
696 /// Emit a bypass check to see if all of the SCEV assumptions we've
697 /// had to make are correct. Returns the block containing the checks or
698 /// nullptr if no checks have been added.
699 BasicBlock *emitSCEVChecks(Loop *L, BasicBlock *Bypass);
700
701 /// Emit bypass checks to check any memory assumptions we may have made.
702 /// Returns the block containing the checks or nullptr if no checks have been
703 /// added.
704 BasicBlock *emitMemRuntimeChecks(Loop *L, BasicBlock *Bypass);
705
706 /// Compute the transformed value of Index at offset StartValue using step
707 /// StepValue.
708 /// For integer induction, returns StartValue + Index * StepValue.
709 /// For pointer induction, returns StartValue[Index * StepValue].
710 /// FIXME: The newly created binary instructions should contain nsw/nuw
711 /// flags, which can be found from the original scalar operations.
712 Value *emitTransformedIndex(IRBuilder<> &B, Value *Index, ScalarEvolution *SE,
713 const DataLayout &DL,
714 const InductionDescriptor &ID) const;
715
716 /// Emit basic blocks (prefixed with \p Prefix) for the iteration check,
717 /// vector loop preheader, middle block and scalar preheader. Also
718 /// allocate a loop object for the new vector loop and return it.
719 Loop *createVectorLoopSkeleton(StringRef Prefix);
720
721 /// Create new phi nodes for the induction variables to resume iteration count
722 /// in the scalar epilogue, from where the vectorized loop left off (given by
723 /// \p VectorTripCount).
724 /// In cases where the loop skeleton is more complicated (eg. epilogue
725 /// vectorization) and the resume values can come from an additional bypass
726 /// block, the \p AdditionalBypass pair provides information about the bypass
727 /// block and the end value on the edge from bypass to this loop.
728 void createInductionResumeValues(
729 Loop *L, Value *VectorTripCount,
730 std::pair<BasicBlock *, Value *> AdditionalBypass = {nullptr, nullptr});
731
732 /// Complete the loop skeleton by adding debug MDs, creating appropriate
733 /// conditional branches in the middle block, preparing the builder and
734 /// running the verifier. Take in the vector loop \p L as argument, and return
735 /// the preheader of the completed vector loop.
736 BasicBlock *completeLoopSkeleton(Loop *L, MDNode *OrigLoopID);
737
738 /// Add additional metadata to \p To that was not present on \p Orig.
739 ///
740 /// Currently this is used to add the noalias annotations based on the
741 /// inserted memchecks. Use this for instructions that are *cloned* into the
742 /// vector loop.
743 void addNewMetadata(Instruction *To, const Instruction *Orig);
744
745 /// Add metadata from one instruction to another.
746 ///
747 /// This includes both the original MDs from \p From and additional ones (\see
748 /// addNewMetadata). Use this for *newly created* instructions in the vector
749 /// loop.
750 void addMetadata(Instruction *To, Instruction *From);
751
752 /// Similar to the previous function but it adds the metadata to a
753 /// vector of instructions.
754 void addMetadata(ArrayRef<Value *> To, Instruction *From);
755
756 /// Allow subclasses to override and print debug traces before/after vplan
757 /// execution, when trace information is requested.
758 virtual void printDebugTracesAtStart(){};
759 virtual void printDebugTracesAtEnd(){};
760
761 /// The original loop.
762 Loop *OrigLoop;
763
764 /// A wrapper around ScalarEvolution used to add runtime SCEV checks. Applies
765 /// dynamic knowledge to simplify SCEV expressions and converts them to a
766 /// more usable form.
767 PredicatedScalarEvolution &PSE;
768
769 /// Loop Info.
770 LoopInfo *LI;
771
772 /// Dominator Tree.
773 DominatorTree *DT;
774
775 /// Alias Analysis.
776 AAResults *AA;
777
778 /// Target Library Info.
779 const TargetLibraryInfo *TLI;
780
781 /// Target Transform Info.
782 const TargetTransformInfo *TTI;
783
784 /// Assumption Cache.
785 AssumptionCache *AC;
786
787 /// Interface to emit optimization remarks.
788 OptimizationRemarkEmitter *ORE;
789
790 /// LoopVersioning. It's only set up (non-null) if memchecks were
791 /// used.
792 ///
793 /// This is currently only used to add no-alias metadata based on the
794 /// memchecks. The actually versioning is performed manually.
795 std::unique_ptr<LoopVersioning> LVer;
796
797 /// The vectorization SIMD factor to use. Each vector will have this many
798 /// vector elements.
799 ElementCount VF;
800
801 /// The vectorization unroll factor to use. Each scalar is vectorized to this
802 /// many different vector instructions.
803 unsigned UF;
804
805 /// The builder that we use
806 IRBuilder<> Builder;
807
808 // --- Vectorization state ---
809
810 /// The vector-loop preheader.
811 BasicBlock *LoopVectorPreHeader;
812
813 /// The scalar-loop preheader.
814 BasicBlock *LoopScalarPreHeader;
815
816 /// Middle Block between the vector and the scalar.
817 BasicBlock *LoopMiddleBlock;
818
819 /// The unique ExitBlock of the scalar loop if one exists. Note that
820 /// there can be multiple exiting edges reaching this block.
821 BasicBlock *LoopExitBlock;
822
823 /// The vector loop body.
824 BasicBlock *LoopVectorBody;
825
826 /// The scalar loop body.
827 BasicBlock *LoopScalarBody;
828
829 /// A list of all bypass blocks. The first block is the entry of the loop.
830 SmallVector<BasicBlock *, 4> LoopBypassBlocks;
831
832 /// The new Induction variable which was added to the new block.
833 PHINode *Induction = nullptr;
834
835 /// The induction variable of the old basic block.
836 PHINode *OldInduction = nullptr;
837
838 /// Store instructions that were predicated.
839 SmallVector<Instruction *, 4> PredicatedInstructions;
840
841 /// Trip count of the original loop.
842 Value *TripCount = nullptr;
843
844 /// Trip count of the widened loop (TripCount - TripCount % (VF*UF))
845 Value *VectorTripCount = nullptr;
846
847 /// The legality analysis.
848 LoopVectorizationLegality *Legal;
849
850 /// The profitablity analysis.
851 LoopVectorizationCostModel *Cost;
852
853 // Record whether runtime checks are added.
854 bool AddedSafetyChecks = false;
855
856 // Holds the end values for each induction variable. We save the end values
857 // so we can later fix-up the external users of the induction variables.
858 DenseMap<PHINode *, Value *> IVEndValues;
859
860 // Vector of original scalar PHIs whose corresponding widened PHIs need to be
861 // fixed up at the end of vector code generation.
862 SmallVector<PHINode *, 8> OrigPHIsToFix;
863
864 /// BFI and PSI are used to check for profile guided size optimizations.
865 BlockFrequencyInfo *BFI;
866 ProfileSummaryInfo *PSI;
867
868 // Whether this loop should be optimized for size based on profile guided size
869 // optimizatios.
870 bool OptForSizeBasedOnProfile;
871
872 /// Structure to hold information about generated runtime checks, responsible
873 /// for cleaning the checks, if vectorization turns out unprofitable.
874 GeneratedRTChecks &RTChecks;
875};
876
877class InnerLoopUnroller : public InnerLoopVectorizer {
878public:
879 InnerLoopUnroller(Loop *OrigLoop, PredicatedScalarEvolution &PSE,
880 LoopInfo *LI, DominatorTree *DT,
881 const TargetLibraryInfo *TLI,
882 const TargetTransformInfo *TTI, AssumptionCache *AC,
883 OptimizationRemarkEmitter *ORE, unsigned UnrollFactor,
884 LoopVectorizationLegality *LVL,
885 LoopVectorizationCostModel *CM, BlockFrequencyInfo *BFI,
886 ProfileSummaryInfo *PSI, GeneratedRTChecks &Check)
887 : InnerLoopVectorizer(OrigLoop, PSE, LI, DT, TLI, TTI, AC, ORE,
888 ElementCount::getFixed(1), UnrollFactor, LVL, CM,
889 BFI, PSI, Check) {}
890
891private:
892 Value *getBroadcastInstrs(Value *V) override;
893 Value *getStepVector(Value *Val, int StartIdx, Value *Step,
894 Instruction::BinaryOps Opcode =
895 Instruction::BinaryOpsEnd) override;
896 Value *reverseVector(Value *Vec) override;
897};
898
899/// Encapsulate information regarding vectorization of a loop and its epilogue.
900/// This information is meant to be updated and used across two stages of
901/// epilogue vectorization.
902struct EpilogueLoopVectorizationInfo {
903 ElementCount MainLoopVF = ElementCount::getFixed(0);
904 unsigned MainLoopUF = 0;
905 ElementCount EpilogueVF = ElementCount::getFixed(0);
906 unsigned EpilogueUF = 0;
907 BasicBlock *MainLoopIterationCountCheck = nullptr;
908 BasicBlock *EpilogueIterationCountCheck = nullptr;
909 BasicBlock *SCEVSafetyCheck = nullptr;
910 BasicBlock *MemSafetyCheck = nullptr;
911 Value *TripCount = nullptr;
912 Value *VectorTripCount = nullptr;
913
914 EpilogueLoopVectorizationInfo(unsigned MVF, unsigned MUF, unsigned EVF,
915 unsigned EUF)
916 : MainLoopVF(ElementCount::getFixed(MVF)), MainLoopUF(MUF),
917 EpilogueVF(ElementCount::getFixed(EVF)), EpilogueUF(EUF) {
918 assert(EUF == 1 &&((void)0)
919 "A high UF for the epilogue loop is likely not beneficial.")((void)0);
920 }
921};
922
923/// An extension of the inner loop vectorizer that creates a skeleton for a
924/// vectorized loop that has its epilogue (residual) also vectorized.
925/// The idea is to run the vplan on a given loop twice, firstly to setup the
926/// skeleton and vectorize the main loop, and secondly to complete the skeleton
927/// from the first step and vectorize the epilogue. This is achieved by
928/// deriving two concrete strategy classes from this base class and invoking
929/// them in succession from the loop vectorizer planner.
930class InnerLoopAndEpilogueVectorizer : public InnerLoopVectorizer {
931public:
932 InnerLoopAndEpilogueVectorizer(
933 Loop *OrigLoop, PredicatedScalarEvolution &PSE, LoopInfo *LI,
934 DominatorTree *DT, const TargetLibraryInfo *TLI,
935 const TargetTransformInfo *TTI, AssumptionCache *AC,
936 OptimizationRemarkEmitter *ORE, EpilogueLoopVectorizationInfo &EPI,
937 LoopVectorizationLegality *LVL, llvm::LoopVectorizationCostModel *CM,
938 BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
939 GeneratedRTChecks &Checks)
940 : InnerLoopVectorizer(OrigLoop, PSE, LI, DT, TLI, TTI, AC, ORE,
941 EPI.MainLoopVF, EPI.MainLoopUF, LVL, CM, BFI, PSI,
942 Checks),
943 EPI(EPI) {}
944
945 // Override this function to handle the more complex control flow around the
946 // three loops.
947 BasicBlock *createVectorizedLoopSkeleton() final override {
948 return createEpilogueVectorizedLoopSkeleton();
949 }
950
951 /// The interface for creating a vectorized skeleton using one of two
952 /// different strategies, each corresponding to one execution of the vplan
953 /// as described above.
954 virtual BasicBlock *createEpilogueVectorizedLoopSkeleton() = 0;
955
956 /// Holds and updates state information required to vectorize the main loop
957 /// and its epilogue in two separate passes. This setup helps us avoid
958 /// regenerating and recomputing runtime safety checks. It also helps us to
959 /// shorten the iteration-count-check path length for the cases where the
960 /// iteration count of the loop is so small that the main vector loop is
961 /// completely skipped.
962 EpilogueLoopVectorizationInfo &EPI;
963};
964
965/// A specialized derived class of inner loop vectorizer that performs
966/// vectorization of *main* loops in the process of vectorizing loops and their
967/// epilogues.
968class EpilogueVectorizerMainLoop : public InnerLoopAndEpilogueVectorizer {
969public:
970 EpilogueVectorizerMainLoop(
971 Loop *OrigLoop, PredicatedScalarEvolution &PSE, LoopInfo *LI,
972 DominatorTree *DT, const TargetLibraryInfo *TLI,
973 const TargetTransformInfo *TTI, AssumptionCache *AC,
974 OptimizationRemarkEmitter *ORE, EpilogueLoopVectorizationInfo &EPI,
975 LoopVectorizationLegality *LVL, llvm::LoopVectorizationCostModel *CM,
976 BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
977 GeneratedRTChecks &Check)
978 : InnerLoopAndEpilogueVectorizer(OrigLoop, PSE, LI, DT, TLI, TTI, AC, ORE,
979 EPI, LVL, CM, BFI, PSI, Check) {}
980 /// Implements the interface for creating a vectorized skeleton using the
981 /// *main loop* strategy (ie the first pass of vplan execution).
982 BasicBlock *createEpilogueVectorizedLoopSkeleton() final override;
983
984protected:
985 /// Emits an iteration count bypass check once for the main loop (when \p
986 /// ForEpilogue is false) and once for the epilogue loop (when \p
987 /// ForEpilogue is true).
988 BasicBlock *emitMinimumIterationCountCheck(Loop *L, BasicBlock *Bypass,
989 bool ForEpilogue);
990 void printDebugTracesAtStart() override;
991 void printDebugTracesAtEnd() override;
992};
993
994// A specialized derived class of inner loop vectorizer that performs
995// vectorization of *epilogue* loops in the process of vectorizing loops and
996// their epilogues.
997class EpilogueVectorizerEpilogueLoop : public InnerLoopAndEpilogueVectorizer {
998public:
999 EpilogueVectorizerEpilogueLoop(
1000 Loop *OrigLoop, PredicatedScalarEvolution &PSE, LoopInfo *LI,
1001 DominatorTree *DT, const TargetLibraryInfo *TLI,
1002 const TargetTransformInfo *TTI, AssumptionCache *AC,
1003 OptimizationRemarkEmitter *ORE, EpilogueLoopVectorizationInfo &EPI,
1004 LoopVectorizationLegality *LVL, llvm::LoopVectorizationCostModel *CM,
1005 BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
1006 GeneratedRTChecks &Checks)
1007 : InnerLoopAndEpilogueVectorizer(OrigLoop, PSE, LI, DT, TLI, TTI, AC, ORE,
1008 EPI, LVL, CM, BFI, PSI, Checks) {}
1009 /// Implements the interface for creating a vectorized skeleton using the
1010 /// *epilogue loop* strategy (ie the second pass of vplan execution).
1011 BasicBlock *createEpilogueVectorizedLoopSkeleton() final override;
1012
1013protected:
1014 /// Emits an iteration count bypass check after the main vector loop has
1015 /// finished to see if there are any iterations left to execute by either
1016 /// the vector epilogue or the scalar epilogue.
1017 BasicBlock *emitMinimumVectorEpilogueIterCountCheck(Loop *L,
1018 BasicBlock *Bypass,
1019 BasicBlock *Insert);
1020 void printDebugTracesAtStart() override;
1021 void printDebugTracesAtEnd() override;
1022};
1023} // end namespace llvm
1024
1025/// Look for a meaningful debug location on the instruction or it's
1026/// operands.
1027static Instruction *getDebugLocFromInstOrOperands(Instruction *I) {
1028 if (!I)
1029 return I;
1030
1031 DebugLoc Empty;
1032 if (I->getDebugLoc() != Empty)
1033 return I;
1034
1035 for (Use &Op : I->operands()) {
1036 if (Instruction *OpInst = dyn_cast<Instruction>(Op))
1037 if (OpInst->getDebugLoc() != Empty)
1038 return OpInst;
1039 }
1040
1041 return I;
1042}
1043
1044void InnerLoopVectorizer::setDebugLocFromInst(
1045 const Value *V, Optional<IRBuilder<> *> CustomBuilder) {
1046 IRBuilder<> *B = (CustomBuilder == None) ? &Builder : *CustomBuilder;
1047 if (const Instruction *Inst = dyn_cast_or_null<Instruction>(V)) {
1048 const DILocation *DIL = Inst->getDebugLoc();
1049
1050 // When a FSDiscriminator is enabled, we don't need to add the multiply
1051 // factors to the discriminators.
1052 if (DIL && Inst->getFunction()->isDebugInfoForProfiling() &&
1053 !isa<DbgInfoIntrinsic>(Inst) && !EnableFSDiscriminator) {
1054 // FIXME: For scalable vectors, assume vscale=1.
1055 auto NewDIL =
1056 DIL->cloneByMultiplyingDuplicationFactor(UF * VF.getKnownMinValue());
1057 if (NewDIL)
1058 B->SetCurrentDebugLocation(NewDIL.getValue());
1059 else
1060 LLVM_DEBUG(dbgs()do { } while (false)
1061 << "Failed to create new discriminator: "do { } while (false)
1062 << DIL->getFilename() << " Line: " << DIL->getLine())do { } while (false);
1063 } else
1064 B->SetCurrentDebugLocation(DIL);
1065 } else
1066 B->SetCurrentDebugLocation(DebugLoc());
1067}
1068
1069/// Write a \p DebugMsg about vectorization to the debug output stream. If \p I
1070/// is passed, the message relates to that particular instruction.
1071#ifndef NDEBUG1
1072static void debugVectorizationMessage(const StringRef Prefix,
1073 const StringRef DebugMsg,
1074 Instruction *I) {
1075 dbgs() << "LV: " << Prefix << DebugMsg;
1076 if (I != nullptr)
1077 dbgs() << " " << *I;
1078 else
1079 dbgs() << '.';
1080 dbgs() << '\n';
1081}
1082#endif
1083
1084/// Create an analysis remark that explains why vectorization failed
1085///
1086/// \p PassName is the name of the pass (e.g. can be AlwaysPrint). \p
1087/// RemarkName is the identifier for the remark. If \p I is passed it is an
1088/// instruction that prevents vectorization. Otherwise \p TheLoop is used for
1089/// the location of the remark. \return the remark object that can be
1090/// streamed to.
1091static OptimizationRemarkAnalysis createLVAnalysis(const char *PassName,
1092 StringRef RemarkName, Loop *TheLoop, Instruction *I) {
1093 Value *CodeRegion = TheLoop->getHeader();
1094 DebugLoc DL = TheLoop->getStartLoc();
1095
1096 if (I) {
1097 CodeRegion = I->getParent();
1098 // If there is no debug location attached to the instruction, revert back to
1099 // using the loop's.
1100 if (I->getDebugLoc())
1101 DL = I->getDebugLoc();
1102 }
1103
1104 return OptimizationRemarkAnalysis(PassName, RemarkName, DL, CodeRegion);
1105}
1106
1107/// Return a value for Step multiplied by VF.
1108static Value *createStepForVF(IRBuilder<> &B, Constant *Step, ElementCount VF) {
1109 assert(isa<ConstantInt>(Step) && "Expected an integer step")((void)0);
1110 Constant *StepVal = ConstantInt::get(
1111 Step->getType(),
1112 cast<ConstantInt>(Step)->getSExtValue() * VF.getKnownMinValue());
1113 return VF.isScalable() ? B.CreateVScale(StepVal) : StepVal;
1114}
1115
1116namespace llvm {
1117
1118/// Return the runtime value for VF.
1119Value *getRuntimeVF(IRBuilder<> &B, Type *Ty, ElementCount VF) {
1120 Constant *EC = ConstantInt::get(Ty, VF.getKnownMinValue());
1121 return VF.isScalable() ? B.CreateVScale(EC) : EC;
1122}
1123
1124void reportVectorizationFailure(const StringRef DebugMsg,
1125 const StringRef OREMsg, const StringRef ORETag,
1126 OptimizationRemarkEmitter *ORE, Loop *TheLoop,
1127 Instruction *I) {
1128 LLVM_DEBUG(debugVectorizationMessage("Not vectorizing: ", DebugMsg, I))do { } while (false);
1129 LoopVectorizeHints Hints(TheLoop, true /* doesn't matter */, *ORE);
1130 ORE->emit(
1131 createLVAnalysis(Hints.vectorizeAnalysisPassName(), ORETag, TheLoop, I)
1132 << "loop not vectorized: " << OREMsg);
1133}
1134
1135void reportVectorizationInfo(const StringRef Msg, const StringRef ORETag,
1136 OptimizationRemarkEmitter *ORE, Loop *TheLoop,
1137 Instruction *I) {
1138 LLVM_DEBUG(debugVectorizationMessage("", Msg, I))do { } while (false);
1139 LoopVectorizeHints Hints(TheLoop, true /* doesn't matter */, *ORE);
1140 ORE->emit(
1141 createLVAnalysis(Hints.vectorizeAnalysisPassName(), ORETag, TheLoop, I)
1142 << Msg);
1143}
1144
1145} // end namespace llvm
1146
1147#ifndef NDEBUG1
1148/// \return string containing a file name and a line # for the given loop.
1149static std::string getDebugLocString(const Loop *L) {
1150 std::string Result;
1151 if (L) {
1152 raw_string_ostream OS(Result);
1153 if (const DebugLoc LoopDbgLoc = L->getStartLoc())
1154 LoopDbgLoc.print(OS);
1155 else
1156 // Just print the module name.
1157 OS << L->getHeader()->getParent()->getParent()->getModuleIdentifier();
1158 OS.flush();
1159 }
1160 return Result;
1161}
1162#endif
1163
1164void InnerLoopVectorizer::addNewMetadata(Instruction *To,
1165 const Instruction *Orig) {
1166 // If the loop was versioned with memchecks, add the corresponding no-alias
1167 // metadata.
1168 if (LVer && (isa<LoadInst>(Orig) || isa<StoreInst>(Orig)))
1169 LVer->annotateInstWithNoAlias(To, Orig);
1170}
1171
1172void InnerLoopVectorizer::addMetadata(Instruction *To,
1173 Instruction *From) {
1174 propagateMetadata(To, From);
1175 addNewMetadata(To, From);
1176}
1177
1178void InnerLoopVectorizer::addMetadata(ArrayRef<Value *> To,
1179 Instruction *From) {
1180 for (Value *V : To) {
1181 if (Instruction *I = dyn_cast<Instruction>(V))
1182 addMetadata(I, From);
1183 }
1184}
1185
1186namespace llvm {
1187
1188// Loop vectorization cost-model hints how the scalar epilogue loop should be
1189// lowered.
1190enum ScalarEpilogueLowering {
1191
1192 // The default: allowing scalar epilogues.
1193 CM_ScalarEpilogueAllowed,
1194
1195 // Vectorization with OptForSize: don't allow epilogues.
1196 CM_ScalarEpilogueNotAllowedOptSize,
1197
1198 // A special case of vectorisation with OptForSize: loops with a very small
1199 // trip count are considered for vectorization under OptForSize, thereby
1200 // making sure the cost of their loop body is dominant, free of runtime
1201 // guards and scalar iteration overheads.
1202 CM_ScalarEpilogueNotAllowedLowTripLoop,
1203
1204 // Loop hint predicate indicating an epilogue is undesired.
1205 CM_ScalarEpilogueNotNeededUsePredicate,
1206
1207 // Directive indicating we must either tail fold or not vectorize
1208 CM_ScalarEpilogueNotAllowedUsePredicate
1209};
1210
1211/// ElementCountComparator creates a total ordering for ElementCount
1212/// for the purposes of using it in a set structure.
1213struct ElementCountComparator {
1214 bool operator()(const ElementCount &LHS, const ElementCount &RHS) const {
1215 return std::make_tuple(LHS.isScalable(), LHS.getKnownMinValue()) <
1216 std::make_tuple(RHS.isScalable(), RHS.getKnownMinValue());
1217 }
1218};
1219using ElementCountSet = SmallSet<ElementCount, 16, ElementCountComparator>;
1220
1221/// LoopVectorizationCostModel - estimates the expected speedups due to
1222/// vectorization.
1223/// In many cases vectorization is not profitable. This can happen because of
1224/// a number of reasons. In this class we mainly attempt to predict the
1225/// expected speedup/slowdowns due to the supported instruction set. We use the
1226/// TargetTransformInfo to query the different backends for the cost of
1227/// different operations.
1228class LoopVectorizationCostModel {
1229public:
1230 LoopVectorizationCostModel(ScalarEpilogueLowering SEL, Loop *L,
1231 PredicatedScalarEvolution &PSE, LoopInfo *LI,
1232 LoopVectorizationLegality *Legal,
1233 const TargetTransformInfo &TTI,
1234 const TargetLibraryInfo *TLI, DemandedBits *DB,
1235 AssumptionCache *AC,
1236 OptimizationRemarkEmitter *ORE, const Function *F,
1237 const LoopVectorizeHints *Hints,
1238 InterleavedAccessInfo &IAI)
1239 : ScalarEpilogueStatus(SEL), TheLoop(L), PSE(PSE), LI(LI), Legal(Legal),
1240 TTI(TTI), TLI(TLI), DB(DB), AC(AC), ORE(ORE), TheFunction(F),
1241 Hints(Hints), InterleaveInfo(IAI) {}
1242
1243 /// \return An upper bound for the vectorization factors (both fixed and
1244 /// scalable). If the factors are 0, vectorization and interleaving should be
1245 /// avoided up front.
1246 FixedScalableVFPair computeMaxVF(ElementCount UserVF, unsigned UserIC);
1247
1248 /// \return True if runtime checks are required for vectorization, and false
1249 /// otherwise.
1250 bool runtimeChecksRequired();
1251
1252 /// \return The most profitable vectorization factor and the cost of that VF.
1253 /// This method checks every VF in \p CandidateVFs. If UserVF is not ZERO
1254 /// then this vectorization factor will be selected if vectorization is
1255 /// possible.
1256 VectorizationFactor
1257 selectVectorizationFactor(const ElementCountSet &CandidateVFs);
1258
1259 VectorizationFactor
1260 selectEpilogueVectorizationFactor(const ElementCount MaxVF,
1261 const LoopVectorizationPlanner &LVP);
1262
1263 /// Setup cost-based decisions for user vectorization factor.
1264 /// \return true if the UserVF is a feasible VF to be chosen.
1265 bool selectUserVectorizationFactor(ElementCount UserVF) {
1266 collectUniformsAndScalars(UserVF);
1267 collectInstsToScalarize(UserVF);
1268 return expectedCost(UserVF).first.isValid();
1269 }
1270
1271 /// \return The size (in bits) of the smallest and widest types in the code
1272 /// that needs to be vectorized. We ignore values that remain scalar such as
1273 /// 64 bit loop indices.
1274 std::pair<unsigned, unsigned> getSmallestAndWidestTypes();
1275
1276 /// \return The desired interleave count.
1277 /// If interleave count has been specified by metadata it will be returned.
1278 /// Otherwise, the interleave count is computed and returned. VF and LoopCost
1279 /// are the selected vectorization factor and the cost of the selected VF.
1280 unsigned selectInterleaveCount(ElementCount VF, unsigned LoopCost);
1281
1282 /// Memory access instruction may be vectorized in more than one way.
1283 /// Form of instruction after vectorization depends on cost.
1284 /// This function takes cost-based decisions for Load/Store instructions
1285 /// and collects them in a map. This decisions map is used for building
1286 /// the lists of loop-uniform and loop-scalar instructions.
1287 /// The calculated cost is saved with widening decision in order to
1288 /// avoid redundant calculations.
1289 void setCostBasedWideningDecision(ElementCount VF);
1290
1291 /// A struct that represents some properties of the register usage
1292 /// of a loop.
1293 struct RegisterUsage {
1294 /// Holds the number of loop invariant values that are used in the loop.
1295 /// The key is ClassID of target-provided register class.
1296 SmallMapVector<unsigned, unsigned, 4> LoopInvariantRegs;
1297 /// Holds the maximum number of concurrent live intervals in the loop.
1298 /// The key is ClassID of target-provided register class.
1299 SmallMapVector<unsigned, unsigned, 4> MaxLocalUsers;
1300 };
1301
1302 /// \return Returns information about the register usages of the loop for the
1303 /// given vectorization factors.
1304 SmallVector<RegisterUsage, 8>
1305 calculateRegisterUsage(ArrayRef<ElementCount> VFs);
1306
1307 /// Collect values we want to ignore in the cost model.
1308 void collectValuesToIgnore();
1309
1310 /// Collect all element types in the loop for which widening is needed.
1311 void collectElementTypesForWidening();
1312
1313 /// Split reductions into those that happen in the loop, and those that happen
1314 /// outside. In loop reductions are collected into InLoopReductionChains.
1315 void collectInLoopReductions();
1316
1317 /// Returns true if we should use strict in-order reductions for the given
1318 /// RdxDesc. This is true if the -enable-strict-reductions flag is passed,
1319 /// the IsOrdered flag of RdxDesc is set and we do not allow reordering
1320 /// of FP operations.
1321 bool useOrderedReductions(const RecurrenceDescriptor &RdxDesc) {
1322 return EnableStrictReductions && !Hints->allowReordering() &&
1323 RdxDesc.isOrdered();
1324 }
1325
1326 /// \returns The smallest bitwidth each instruction can be represented with.
1327 /// The vector equivalents of these instructions should be truncated to this
1328 /// type.
1329 const MapVector<Instruction *, uint64_t> &getMinimalBitwidths() const {
1330 return MinBWs;
1331 }
1332
1333 /// \returns True if it is more profitable to scalarize instruction \p I for
1334 /// vectorization factor \p VF.
1335 bool isProfitableToScalarize(Instruction *I, ElementCount VF) const {
1336 assert(VF.isVector() &&((void)0)
1337 "Profitable to scalarize relevant only for VF > 1.")((void)0);
1338
1339 // Cost model is not run in the VPlan-native path - return conservative
1340 // result until this changes.
1341 if (EnableVPlanNativePath)
1342 return false;
1343
1344 auto Scalars = InstsToScalarize.find(VF);
1345 assert(Scalars != InstsToScalarize.end() &&((void)0)
1346 "VF not yet analyzed for scalarization profitability")((void)0);
1347 return Scalars->second.find(I) != Scalars->second.end();
1348 }
1349
1350 /// Returns true if \p I is known to be uniform after vectorization.
1351 bool isUniformAfterVectorization(Instruction *I, ElementCount VF) const {
1352 if (VF.isScalar())
1353 return true;
1354
1355 // Cost model is not run in the VPlan-native path - return conservative
1356 // result until this changes.
1357 if (EnableVPlanNativePath)
1358 return false;
1359
1360 auto UniformsPerVF = Uniforms.find(VF);
1361 assert(UniformsPerVF != Uniforms.end() &&((void)0)
1362 "VF not yet analyzed for uniformity")((void)0);
1363 return UniformsPerVF->second.count(I);
1364 }
1365
1366 /// Returns true if \p I is known to be scalar after vectorization.
1367 bool isScalarAfterVectorization(Instruction *I, ElementCount VF) const {
1368 if (VF.isScalar())
1369 return true;
1370
1371 // Cost model is not run in the VPlan-native path - return conservative
1372 // result until this changes.
1373 if (EnableVPlanNativePath)
1374 return false;
1375
1376 auto ScalarsPerVF = Scalars.find(VF);
1377 assert(ScalarsPerVF != Scalars.end() &&((void)0)
1378 "Scalar values are not calculated for VF")((void)0);
1379 return ScalarsPerVF->second.count(I);
1380 }
1381
1382 /// \returns True if instruction \p I can be truncated to a smaller bitwidth
1383 /// for vectorization factor \p VF.
1384 bool canTruncateToMinimalBitwidth(Instruction *I, ElementCount VF) const {
1385 return VF.isVector() && MinBWs.find(I) != MinBWs.end() &&
1386 !isProfitableToScalarize(I, VF) &&
1387 !isScalarAfterVectorization(I, VF);
1388 }
1389
1390 /// Decision that was taken during cost calculation for memory instruction.
1391 enum InstWidening {
1392 CM_Unknown,
1393 CM_Widen, // For consecutive accesses with stride +1.
1394 CM_Widen_Reverse, // For consecutive accesses with stride -1.
1395 CM_Interleave,
1396 CM_GatherScatter,
1397 CM_Scalarize
1398 };
1399
1400 /// Save vectorization decision \p W and \p Cost taken by the cost model for
1401 /// instruction \p I and vector width \p VF.
1402 void setWideningDecision(Instruction *I, ElementCount VF, InstWidening W,
1403 InstructionCost Cost) {
1404 assert(VF.isVector() && "Expected VF >=2")((void)0);
1405 WideningDecisions[std::make_pair(I, VF)] = std::make_pair(W, Cost);
1406 }
1407
1408 /// Save vectorization decision \p W and \p Cost taken by the cost model for
1409 /// interleaving group \p Grp and vector width \p VF.
1410 void setWideningDecision(const InterleaveGroup<Instruction> *Grp,
1411 ElementCount VF, InstWidening W,
1412 InstructionCost Cost) {
1413 assert(VF.isVector() && "Expected VF >=2")((void)0);
1414 /// Broadcast this decicion to all instructions inside the group.
1415 /// But the cost will be assigned to one instruction only.
1416 for (unsigned i = 0; i < Grp->getFactor(); ++i) {
1417 if (auto *I = Grp->getMember(i)) {
1418 if (Grp->getInsertPos() == I)
1419 WideningDecisions[std::make_pair(I, VF)] = std::make_pair(W, Cost);
1420 else
1421 WideningDecisions[std::make_pair(I, VF)] = std::make_pair(W, 0);
1422 }
1423 }
1424 }
1425
1426 /// Return the cost model decision for the given instruction \p I and vector
1427 /// width \p VF. Return CM_Unknown if this instruction did not pass
1428 /// through the cost modeling.
1429 InstWidening getWideningDecision(Instruction *I, ElementCount VF) const {
1430 assert(VF.isVector() && "Expected VF to be a vector VF")((void)0);
1431 // Cost model is not run in the VPlan-native path - return conservative
1432 // result until this changes.
1433 if (EnableVPlanNativePath)
1434 return CM_GatherScatter;
1435
1436 std::pair<Instruction *, ElementCount> InstOnVF = std::make_pair(I, VF);
1437 auto Itr = WideningDecisions.find(InstOnVF);
1438 if (Itr == WideningDecisions.end())
1439 return CM_Unknown;
1440 return Itr->second.first;
1441 }
1442
1443 /// Return the vectorization cost for the given instruction \p I and vector
1444 /// width \p VF.
1445 InstructionCost getWideningCost(Instruction *I, ElementCount VF) {
1446 assert(VF.isVector() && "Expected VF >=2")((void)0);
1447 std::pair<Instruction *, ElementCount> InstOnVF = std::make_pair(I, VF);
1448 assert(WideningDecisions.find(InstOnVF) != WideningDecisions.end() &&((void)0)
1449 "The cost is not calculated")((void)0);
1450 return WideningDecisions[InstOnVF].second;
1451 }
1452
1453 /// Return True if instruction \p I is an optimizable truncate whose operand
1454 /// is an induction variable. Such a truncate will be removed by adding a new
1455 /// induction variable with the destination type.
1456 bool isOptimizableIVTruncate(Instruction *I, ElementCount VF) {
1457 // If the instruction is not a truncate, return false.
1458 auto *Trunc = dyn_cast<TruncInst>(I);
1459 if (!Trunc)
1460 return false;
1461
1462 // Get the source and destination types of the truncate.
1463 Type *SrcTy = ToVectorTy(cast<CastInst>(I)->getSrcTy(), VF);
1464 Type *DestTy = ToVectorTy(cast<CastInst>(I)->getDestTy(), VF);
1465
1466 // If the truncate is free for the given types, return false. Replacing a
1467 // free truncate with an induction variable would add an induction variable
1468 // update instruction to each iteration of the loop. We exclude from this
1469 // check the primary induction variable since it will need an update
1470 // instruction regardless.
1471 Value *Op = Trunc->getOperand(0);
1472 if (Op != Legal->getPrimaryInduction() && TTI.isTruncateFree(SrcTy, DestTy))
1473 return false;
1474
1475 // If the truncated value is not an induction variable, return false.
1476 return Legal->isInductionPhi(Op);
1477 }
1478
1479 /// Collects the instructions to scalarize for each predicated instruction in
1480 /// the loop.
1481 void collectInstsToScalarize(ElementCount VF);
1482
1483 /// Collect Uniform and Scalar values for the given \p VF.
1484 /// The sets depend on CM decision for Load/Store instructions
1485 /// that may be vectorized as interleave, gather-scatter or scalarized.
1486 void collectUniformsAndScalars(ElementCount VF) {
1487 // Do the analysis once.
1488 if (VF.isScalar() || Uniforms.find(VF) != Uniforms.end())
1489 return;
1490 setCostBasedWideningDecision(VF);
1491 collectLoopUniforms(VF);
1492 collectLoopScalars(VF);
1493 }
1494
1495 /// Returns true if the target machine supports masked store operation
1496 /// for the given \p DataType and kind of access to \p Ptr.
1497 bool isLegalMaskedStore(Type *DataType, Value *Ptr, Align Alignment) const {
1498 return Legal->isConsecutivePtr(Ptr) &&
1499 TTI.isLegalMaskedStore(DataType, Alignment);
1500 }
1501
1502 /// Returns true if the target machine supports masked load operation
1503 /// for the given \p DataType and kind of access to \p Ptr.
1504 bool isLegalMaskedLoad(Type *DataType, Value *Ptr, Align Alignment) const {
1505 return Legal->isConsecutivePtr(Ptr) &&
1506 TTI.isLegalMaskedLoad(DataType, Alignment);
1507 }
1508
1509 /// Returns true if the target machine can represent \p V as a masked gather
1510 /// or scatter operation.
1511 bool isLegalGatherOrScatter(Value *V) {
1512 bool LI = isa<LoadInst>(V);
1513 bool SI = isa<StoreInst>(V);
1514 if (!LI && !SI)
1515 return false;
1516 auto *Ty = getLoadStoreType(V);
1517 Align Align = getLoadStoreAlignment(V);
1518 return (LI && TTI.isLegalMaskedGather(Ty, Align)) ||
1519 (SI && TTI.isLegalMaskedScatter(Ty, Align));
1520 }
1521
1522 /// Returns true if the target machine supports all of the reduction
1523 /// variables found for the given VF.
1524 bool canVectorizeReductions(ElementCount VF) const {
1525 return (all_of(Legal->getReductionVars(), [&](auto &Reduction) -> bool {
1526 const RecurrenceDescriptor &RdxDesc = Reduction.second;
1527 return TTI.isLegalToVectorizeReduction(RdxDesc, VF);
1528 }));
1529 }
1530
1531 /// Returns true if \p I is an instruction that will be scalarized with
1532 /// predication. Such instructions include conditional stores and
1533 /// instructions that may divide by zero.
1534 /// If a non-zero VF has been calculated, we check if I will be scalarized
1535 /// predication for that VF.
1536 bool isScalarWithPredication(Instruction *I) const;
1537
1538 // Returns true if \p I is an instruction that will be predicated either
1539 // through scalar predication or masked load/store or masked gather/scatter.
1540 // Superset of instructions that return true for isScalarWithPredication.
1541 bool isPredicatedInst(Instruction *I) {
1542 if (!blockNeedsPredication(I->getParent()))
1543 return false;
1544 // Loads and stores that need some form of masked operation are predicated
1545 // instructions.
1546 if (isa<LoadInst>(I) || isa<StoreInst>(I))
1547 return Legal->isMaskRequired(I);
1548 return isScalarWithPredication(I);
1549 }
1550
1551 /// Returns true if \p I is a memory instruction with consecutive memory
1552 /// access that can be widened.
1553 bool
1554 memoryInstructionCanBeWidened(Instruction *I,
1555 ElementCount VF = ElementCount::getFixed(1));
1556
1557 /// Returns true if \p I is a memory instruction in an interleaved-group
1558 /// of memory accesses that can be vectorized with wide vector loads/stores
1559 /// and shuffles.
1560 bool
1561 interleavedAccessCanBeWidened(Instruction *I,
1562 ElementCount VF = ElementCount::getFixed(1));
1563
1564 /// Check if \p Instr belongs to any interleaved access group.
1565 bool isAccessInterleaved(Instruction *Instr) {
1566 return InterleaveInfo.isInterleaved(Instr);
1567 }
1568
1569 /// Get the interleaved access group that \p Instr belongs to.
1570 const InterleaveGroup<Instruction> *
1571 getInterleavedAccessGroup(Instruction *Instr) {
1572 return InterleaveInfo.getInterleaveGroup(Instr);
1573 }
1574
1575 /// Returns true if we're required to use a scalar epilogue for at least
1576 /// the final iteration of the original loop.
1577 bool requiresScalarEpilogue(ElementCount VF) const {
1578 if (!isScalarEpilogueAllowed())
1579 return false;
1580 // If we might exit from anywhere but the latch, must run the exiting
1581 // iteration in scalar form.
1582 if (TheLoop->getExitingBlock() != TheLoop->getLoopLatch())
1583 return true;
1584 return VF.isVector() && InterleaveInfo.requiresScalarEpilogue();
1585 }
1586
1587 /// Returns true if a scalar epilogue is not allowed due to optsize or a
1588 /// loop hint annotation.
1589 bool isScalarEpilogueAllowed() const {
1590 return ScalarEpilogueStatus == CM_ScalarEpilogueAllowed;
1591 }
1592
1593 /// Returns true if all loop blocks should be masked to fold tail loop.
1594 bool foldTailByMasking() const { return FoldTailByMasking; }
1595
1596 bool blockNeedsPredication(BasicBlock *BB) const {
1597 return foldTailByMasking() || Legal->blockNeedsPredication(BB);
1598 }
1599
1600 /// A SmallMapVector to store the InLoop reduction op chains, mapping phi
1601 /// nodes to the chain of instructions representing the reductions. Uses a
1602 /// MapVector to ensure deterministic iteration order.
1603 using ReductionChainMap =
1604 SmallMapVector<PHINode *, SmallVector<Instruction *, 4>, 4>;
1605
1606 /// Return the chain of instructions representing an inloop reduction.
1607 const ReductionChainMap &getInLoopReductionChains() const {
1608 return InLoopReductionChains;
1609 }
1610
1611 /// Returns true if the Phi is part of an inloop reduction.
1612 bool isInLoopReduction(PHINode *Phi) const {
1613 return InLoopReductionChains.count(Phi);
1614 }
1615
1616 /// Estimate cost of an intrinsic call instruction CI if it were vectorized
1617 /// with factor VF. Return the cost of the instruction, including
1618 /// scalarization overhead if it's needed.
1619 InstructionCost getVectorIntrinsicCost(CallInst *CI, ElementCount VF) const;
1620
1621 /// Estimate cost of a call instruction CI if it were vectorized with factor
1622 /// VF. Return the cost of the instruction, including scalarization overhead
1623 /// if it's needed. The flag NeedToScalarize shows if the call needs to be
1624 /// scalarized -
1625 /// i.e. either vector version isn't available, or is too expensive.
1626 InstructionCost getVectorCallCost(CallInst *CI, ElementCount VF,
1627 bool &NeedToScalarize) const;
1628
1629 /// Returns true if the per-lane cost of VectorizationFactor A is lower than
1630 /// that of B.
1631 bool isMoreProfitable(const VectorizationFactor &A,
1632 const VectorizationFactor &B) const;
1633
1634 /// Invalidates decisions already taken by the cost model.
1635 void invalidateCostModelingDecisions() {
1636 WideningDecisions.clear();
1637 Uniforms.clear();
1638 Scalars.clear();
1639 }
1640
1641private:
1642 unsigned NumPredStores = 0;
1643
1644 /// \return An upper bound for the vectorization factors for both
1645 /// fixed and scalable vectorization, where the minimum-known number of
1646 /// elements is a power-of-2 larger than zero. If scalable vectorization is
1647 /// disabled or unsupported, then the scalable part will be equal to
1648 /// ElementCount::getScalable(0).
1649 FixedScalableVFPair computeFeasibleMaxVF(unsigned ConstTripCount,
1650 ElementCount UserVF);
1651
1652 /// \return the maximized element count based on the targets vector
1653 /// registers and the loop trip-count, but limited to a maximum safe VF.
1654 /// This is a helper function of computeFeasibleMaxVF.
1655 /// FIXME: MaxSafeVF is currently passed by reference to avoid some obscure
1656 /// issue that occurred on one of the buildbots which cannot be reproduced
1657 /// without having access to the properietary compiler (see comments on
1658 /// D98509). The issue is currently under investigation and this workaround
1659 /// will be removed as soon as possible.
1660 ElementCount getMaximizedVFForTarget(unsigned ConstTripCount,
1661 unsigned SmallestType,
1662 unsigned WidestType,
1663 const ElementCount &MaxSafeVF);
1664
1665 /// \return the maximum legal scalable VF, based on the safe max number
1666 /// of elements.
1667 ElementCount getMaxLegalScalableVF(unsigned MaxSafeElements);
1668
1669 /// The vectorization cost is a combination of the cost itself and a boolean
1670 /// indicating whether any of the contributing operations will actually
1671 /// operate on vector values after type legalization in the backend. If this
1672 /// latter value is false, then all operations will be scalarized (i.e. no
1673 /// vectorization has actually taken place).
1674 using VectorizationCostTy = std::pair<InstructionCost, bool>;
1675
1676 /// Returns the expected execution cost. The unit of the cost does
1677 /// not matter because we use the 'cost' units to compare different
1678 /// vector widths. The cost that is returned is *not* normalized by
1679 /// the factor width. If \p Invalid is not nullptr, this function
1680 /// will add a pair(Instruction*, ElementCount) to \p Invalid for
1681 /// each instruction that has an Invalid cost for the given VF.
1682 using InstructionVFPair = std::pair<Instruction *, ElementCount>;
1683 VectorizationCostTy
1684 expectedCost(ElementCount VF,
1685 SmallVectorImpl<InstructionVFPair> *Invalid = nullptr);
1686
1687 /// Returns the execution time cost of an instruction for a given vector
1688 /// width. Vector width of one means scalar.
1689 VectorizationCostTy getInstructionCost(Instruction *I, ElementCount VF);
1690
1691 /// The cost-computation logic from getInstructionCost which provides
1692 /// the vector type as an output parameter.
1693 InstructionCost getInstructionCost(Instruction *I, ElementCount VF,
1694 Type *&VectorTy);
1695
1696 /// Return the cost of instructions in an inloop reduction pattern, if I is
1697 /// part of that pattern.
1698 Optional<InstructionCost>
1699 getReductionPatternCost(Instruction *I, ElementCount VF, Type *VectorTy,
1700 TTI::TargetCostKind CostKind);
1701
1702 /// Calculate vectorization cost of memory instruction \p I.
1703 InstructionCost getMemoryInstructionCost(Instruction *I, ElementCount VF);
1704
1705 /// The cost computation for scalarized memory instruction.
1706 InstructionCost getMemInstScalarizationCost(Instruction *I, ElementCount VF);
1707
1708 /// The cost computation for interleaving group of memory instructions.
1709 InstructionCost getInterleaveGroupCost(Instruction *I, ElementCount VF);
1710
1711 /// The cost computation for Gather/Scatter instruction.
1712 InstructionCost getGatherScatterCost(Instruction *I, ElementCount VF);
1713
1714 /// The cost computation for widening instruction \p I with consecutive
1715 /// memory access.
1716 InstructionCost getConsecutiveMemOpCost(Instruction *I, ElementCount VF);
1717
1718 /// The cost calculation for Load/Store instruction \p I with uniform pointer -
1719 /// Load: scalar load + broadcast.
1720 /// Store: scalar store + (loop invariant value stored? 0 : extract of last
1721 /// element)
1722 InstructionCost getUniformMemOpCost(Instruction *I, ElementCount VF);
1723
1724 /// Estimate the overhead of scalarizing an instruction. This is a
1725 /// convenience wrapper for the type-based getScalarizationOverhead API.
1726 InstructionCost getScalarizationOverhead(Instruction *I,
1727 ElementCount VF) const;
1728
1729 /// Returns whether the instruction is a load or store and will be a emitted
1730 /// as a vector operation.
1731 bool isConsecutiveLoadOrStore(Instruction *I);
1732
1733 /// Returns true if an artificially high cost for emulated masked memrefs
1734 /// should be used.
1735 bool useEmulatedMaskMemRefHack(Instruction *I);
1736
1737 /// Map of scalar integer values to the smallest bitwidth they can be legally
1738 /// represented as. The vector equivalents of these values should be truncated
1739 /// to this type.
1740 MapVector<Instruction *, uint64_t> MinBWs;
1741
1742 /// A type representing the costs for instructions if they were to be
1743 /// scalarized rather than vectorized. The entries are Instruction-Cost
1744 /// pairs.
1745 using ScalarCostsTy = DenseMap<Instruction *, InstructionCost>;
1746
1747 /// A set containing all BasicBlocks that are known to present after
1748 /// vectorization as a predicated block.
1749 SmallPtrSet<BasicBlock *, 4> PredicatedBBsAfterVectorization;
1750
1751 /// Records whether it is allowed to have the original scalar loop execute at
1752 /// least once. This may be needed as a fallback loop in case runtime
1753 /// aliasing/dependence checks fail, or to handle the tail/remainder
1754 /// iterations when the trip count is unknown or doesn't divide by the VF,
1755 /// or as a peel-loop to handle gaps in interleave-groups.
1756 /// Under optsize and when the trip count is very small we don't allow any
1757 /// iterations to execute in the scalar loop.
1758 ScalarEpilogueLowering ScalarEpilogueStatus = CM_ScalarEpilogueAllowed;
1759
1760 /// All blocks of loop are to be masked to fold tail of scalar iterations.
1761 bool FoldTailByMasking = false;
1762
1763 /// A map holding scalar costs for different vectorization factors. The
1764 /// presence of a cost for an instruction in the mapping indicates that the
1765 /// instruction will be scalarized when vectorizing with the associated
1766 /// vectorization factor. The entries are VF-ScalarCostTy pairs.
1767 DenseMap<ElementCount, ScalarCostsTy> InstsToScalarize;
1768
1769 /// Holds the instructions known to be uniform after vectorization.
1770 /// The data is collected per VF.
1771 DenseMap<ElementCount, SmallPtrSet<Instruction *, 4>> Uniforms;
1772
1773 /// Holds the instructions known to be scalar after vectorization.
1774 /// The data is collected per VF.
1775 DenseMap<ElementCount, SmallPtrSet<Instruction *, 4>> Scalars;
1776
1777 /// Holds the instructions (address computations) that are forced to be
1778 /// scalarized.
1779 DenseMap<ElementCount, SmallPtrSet<Instruction *, 4>> ForcedScalars;
1780
1781 /// PHINodes of the reductions that should be expanded in-loop along with
1782 /// their associated chains of reduction operations, in program order from top
1783 /// (PHI) to bottom
1784 ReductionChainMap InLoopReductionChains;
1785
1786 /// A Map of inloop reduction operations and their immediate chain operand.
1787 /// FIXME: This can be removed once reductions can be costed correctly in
1788 /// vplan. This was added to allow quick lookup to the inloop operations,
1789 /// without having to loop through InLoopReductionChains.
1790 DenseMap<Instruction *, Instruction *> InLoopReductionImmediateChains;
1791
1792 /// Returns the expected difference in cost from scalarizing the expression
1793 /// feeding a predicated instruction \p PredInst. The instructions to
1794 /// scalarize and their scalar costs are collected in \p ScalarCosts. A
1795 /// non-negative return value implies the expression will be scalarized.
1796 /// Currently, only single-use chains are considered for scalarization.
1797 int computePredInstDiscount(Instruction *PredInst, ScalarCostsTy &ScalarCosts,
1798 ElementCount VF);
1799
1800 /// Collect the instructions that are uniform after vectorization. An
1801 /// instruction is uniform if we represent it with a single scalar value in
1802 /// the vectorized loop corresponding to each vector iteration. Examples of
1803 /// uniform instructions include pointer operands of consecutive or
1804 /// interleaved memory accesses. Note that although uniformity implies an
1805 /// instruction will be scalar, the reverse is not true. In general, a
1806 /// scalarized instruction will be represented by VF scalar values in the
1807 /// vectorized loop, each corresponding to an iteration of the original
1808 /// scalar loop.
1809 void collectLoopUniforms(ElementCount VF);
1810
1811 /// Collect the instructions that are scalar after vectorization. An
1812 /// instruction is scalar if it is known to be uniform or will be scalarized
1813 /// during vectorization. Non-uniform scalarized instructions will be
1814 /// represented by VF values in the vectorized loop, each corresponding to an
1815 /// iteration of the original scalar loop.
1816 void collectLoopScalars(ElementCount VF);
1817
1818 /// Keeps cost model vectorization decision and cost for instructions.
1819 /// Right now it is used for memory instructions only.
1820 using DecisionList = DenseMap<std::pair<Instruction *, ElementCount>,
1821 std::pair<InstWidening, InstructionCost>>;
1822
1823 DecisionList WideningDecisions;
1824
1825 /// Returns true if \p V is expected to be vectorized and it needs to be
1826 /// extracted.
1827 bool needsExtract(Value *V, ElementCount VF) const {
1828 Instruction *I = dyn_cast<Instruction>(V);
1829 if (VF.isScalar() || !I || !TheLoop->contains(I) ||
1830 TheLoop->isLoopInvariant(I))
1831 return false;
1832
1833 // Assume we can vectorize V (and hence we need extraction) if the
1834 // scalars are not computed yet. This can happen, because it is called
1835 // via getScalarizationOverhead from setCostBasedWideningDecision, before
1836 // the scalars are collected. That should be a safe assumption in most
1837 // cases, because we check if the operands have vectorizable types
1838 // beforehand in LoopVectorizationLegality.
1839 return Scalars.find(VF) == Scalars.end() ||
1840 !isScalarAfterVectorization(I, VF);
1841 };
1842
1843 /// Returns a range containing only operands needing to be extracted.
1844 SmallVector<Value *, 4> filterExtractingOperands(Instruction::op_range Ops,
1845 ElementCount VF) const {
1846 return SmallVector<Value *, 4>(make_filter_range(
1847 Ops, [this, VF](Value *V) { return this->needsExtract(V, VF); }));
1848 }
1849
1850 /// Determines if we have the infrastructure to vectorize loop \p L and its
1851 /// epilogue, assuming the main loop is vectorized by \p VF.
1852 bool isCandidateForEpilogueVectorization(const Loop &L,
1853 const ElementCount VF) const;
1854
1855 /// Returns true if epilogue vectorization is considered profitable, and
1856 /// false otherwise.
1857 /// \p VF is the vectorization factor chosen for the original loop.
1858 bool isEpilogueVectorizationProfitable(const ElementCount VF) const;
1859
1860public:
1861 /// The loop that we evaluate.
1862 Loop *TheLoop;
1863
1864 /// Predicated scalar evolution analysis.
1865 PredicatedScalarEvolution &PSE;
1866
1867 /// Loop Info analysis.
1868 LoopInfo *LI;
1869
1870 /// Vectorization legality.
1871 LoopVectorizationLegality *Legal;
1872
1873 /// Vector target information.
1874 const TargetTransformInfo &TTI;
1875
1876 /// Target Library Info.
1877 const TargetLibraryInfo *TLI;
1878
1879 /// Demanded bits analysis.
1880 DemandedBits *DB;
1881
1882 /// Assumption cache.
1883 AssumptionCache *AC;
1884
1885 /// Interface to emit optimization remarks.
1886 OptimizationRemarkEmitter *ORE;
1887
1888 const Function *TheFunction;
1889
1890 /// Loop Vectorize Hint.
1891 const LoopVectorizeHints *Hints;
1892
1893 /// The interleave access information contains groups of interleaved accesses
1894 /// with the same stride and close to each other.
1895 InterleavedAccessInfo &InterleaveInfo;
1896
1897 /// Values to ignore in the cost model.
1898 SmallPtrSet<const Value *, 16> ValuesToIgnore;
1899
1900 /// Values to ignore in the cost model when VF > 1.
1901 SmallPtrSet<const Value *, 16> VecValuesToIgnore;
1902
1903 /// All element types found in the loop.
1904 SmallPtrSet<Type *, 16> ElementTypesInLoop;
1905
1906 /// Profitable vector factors.
1907 SmallVector<VectorizationFactor, 8> ProfitableVFs;
1908};
1909} // end namespace llvm
1910
1911/// Helper struct to manage generating runtime checks for vectorization.
1912///
1913/// The runtime checks are created up-front in temporary blocks to allow better
1914/// estimating the cost and un-linked from the existing IR. After deciding to
1915/// vectorize, the checks are moved back. If deciding not to vectorize, the
1916/// temporary blocks are completely removed.
1917class GeneratedRTChecks {
1918 /// Basic block which contains the generated SCEV checks, if any.
1919 BasicBlock *SCEVCheckBlock = nullptr;
1920
1921 /// The value representing the result of the generated SCEV checks. If it is
1922 /// nullptr, either no SCEV checks have been generated or they have been used.
1923 Value *SCEVCheckCond = nullptr;
1924
1925 /// Basic block which contains the generated memory runtime checks, if any.
1926 BasicBlock *MemCheckBlock = nullptr;
1927
1928 /// The value representing the result of the generated memory runtime checks.
1929 /// If it is nullptr, either no memory runtime checks have been generated or
1930 /// they have been used.
1931 Instruction *MemRuntimeCheckCond = nullptr;
1932
1933 DominatorTree *DT;
1934 LoopInfo *LI;
1935
1936 SCEVExpander SCEVExp;
1937 SCEVExpander MemCheckExp;
1938
1939public:
1940 GeneratedRTChecks(ScalarEvolution &SE, DominatorTree *DT, LoopInfo *LI,
1941 const DataLayout &DL)
1942 : DT(DT), LI(LI), SCEVExp(SE, DL, "scev.check"),
1943 MemCheckExp(SE, DL, "scev.check") {}
1944
1945 /// Generate runtime checks in SCEVCheckBlock and MemCheckBlock, so we can
1946 /// accurately estimate the cost of the runtime checks. The blocks are
1947 /// un-linked from the IR and is added back during vector code generation. If
1948 /// there is no vector code generation, the check blocks are removed
1949 /// completely.
1950 void Create(Loop *L, const LoopAccessInfo &LAI,
1951 const SCEVUnionPredicate &UnionPred) {
1952
1953 BasicBlock *LoopHeader = L->getHeader();
1954 BasicBlock *Preheader = L->getLoopPreheader();
1955
1956 // Use SplitBlock to create blocks for SCEV & memory runtime checks to
1957 // ensure the blocks are properly added to LoopInfo & DominatorTree. Those
1958 // may be used by SCEVExpander. The blocks will be un-linked from their
1959 // predecessors and removed from LI & DT at the end of the function.
1960 if (!UnionPred.isAlwaysTrue()) {
1961 SCEVCheckBlock = SplitBlock(Preheader, Preheader->getTerminator(), DT, LI,
1962 nullptr, "vector.scevcheck");
1963
1964 SCEVCheckCond = SCEVExp.expandCodeForPredicate(
1965 &UnionPred, SCEVCheckBlock->getTerminator());
1966 }
1967
1968 const auto &RtPtrChecking = *LAI.getRuntimePointerChecking();
1969 if (RtPtrChecking.Need) {
1970 auto *Pred = SCEVCheckBlock ? SCEVCheckBlock : Preheader;
1971 MemCheckBlock = SplitBlock(Pred, Pred->getTerminator(), DT, LI, nullptr,
1972 "vector.memcheck");
1973
1974 std::tie(std::ignore, MemRuntimeCheckCond) =
1975 addRuntimeChecks(MemCheckBlock->getTerminator(), L,
1976 RtPtrChecking.getChecks(), MemCheckExp);
1977 assert(MemRuntimeCheckCond &&((void)0)
1978 "no RT checks generated although RtPtrChecking "((void)0)
1979 "claimed checks are required")((void)0);
1980 }
1981
1982 if (!MemCheckBlock && !SCEVCheckBlock)
1983 return;
1984
1985 // Unhook the temporary block with the checks, update various places
1986 // accordingly.
1987 if (SCEVCheckBlock)
1988 SCEVCheckBlock->replaceAllUsesWith(Preheader);
1989 if (MemCheckBlock)
1990 MemCheckBlock->replaceAllUsesWith(Preheader);
1991
1992 if (SCEVCheckBlock) {
1993 SCEVCheckBlock->getTerminator()->moveBefore(Preheader->getTerminator());
1994 new UnreachableInst(Preheader->getContext(), SCEVCheckBlock);
1995 Preheader->getTerminator()->eraseFromParent();
1996 }
1997 if (MemCheckBlock) {
1998 MemCheckBlock->getTerminator()->moveBefore(Preheader->getTerminator());
1999 new UnreachableInst(Preheader->getContext(), MemCheckBlock);
2000 Preheader->getTerminator()->eraseFromParent();
2001 }
2002
2003 DT->changeImmediateDominator(LoopHeader, Preheader);
2004 if (MemCheckBlock) {
2005 DT->eraseNode(MemCheckBlock);
2006 LI->removeBlock(MemCheckBlock);
2007 }
2008 if (SCEVCheckBlock) {
2009 DT->eraseNode(SCEVCheckBlock);
2010 LI->removeBlock(SCEVCheckBlock);
2011 }
2012 }
2013
2014 /// Remove the created SCEV & memory runtime check blocks & instructions, if
2015 /// unused.
2016 ~GeneratedRTChecks() {
2017 SCEVExpanderCleaner SCEVCleaner(SCEVExp, *DT);
2018 SCEVExpanderCleaner MemCheckCleaner(MemCheckExp, *DT);
2019 if (!SCEVCheckCond)
2020 SCEVCleaner.markResultUsed();
2021
2022 if (!MemRuntimeCheckCond)
2023 MemCheckCleaner.markResultUsed();
2024
2025 if (MemRuntimeCheckCond) {
2026 auto &SE = *MemCheckExp.getSE();
2027 // Memory runtime check generation creates compares that use expanded
2028 // values. Remove them before running the SCEVExpanderCleaners.
2029 for (auto &I : make_early_inc_range(reverse(*MemCheckBlock))) {
2030 if (MemCheckExp.isInsertedInstruction(&I))
2031 continue;
2032 SE.forgetValue(&I);
2033 SE.eraseValueFromMap(&I);
2034 I.eraseFromParent();
2035 }
2036 }
2037 MemCheckCleaner.cleanup();
2038 SCEVCleaner.cleanup();
2039
2040 if (SCEVCheckCond)
2041 SCEVCheckBlock->eraseFromParent();
2042 if (MemRuntimeCheckCond)
2043 MemCheckBlock->eraseFromParent();
2044 }
2045
2046 /// Adds the generated SCEVCheckBlock before \p LoopVectorPreHeader and
2047 /// adjusts the branches to branch to the vector preheader or \p Bypass,
2048 /// depending on the generated condition.
2049 BasicBlock *emitSCEVChecks(Loop *L, BasicBlock *Bypass,
2050 BasicBlock *LoopVectorPreHeader,
2051 BasicBlock *LoopExitBlock) {
2052 if (!SCEVCheckCond)
2053 return nullptr;
2054 if (auto *C = dyn_cast<ConstantInt>(SCEVCheckCond))
2055 if (C->isZero())
2056 return nullptr;
2057
2058 auto *Pred = LoopVectorPreHeader->getSinglePredecessor();
2059
2060 BranchInst::Create(LoopVectorPreHeader, SCEVCheckBlock);
2061 // Create new preheader for vector loop.
2062 if (auto *PL = LI->getLoopFor(LoopVectorPreHeader))
2063 PL->addBasicBlockToLoop(SCEVCheckBlock, *LI);
2064
2065 SCEVCheckBlock->getTerminator()->eraseFromParent();
2066 SCEVCheckBlock->moveBefore(LoopVectorPreHeader);
2067 Pred->getTerminator()->replaceSuccessorWith(LoopVectorPreHeader,
2068 SCEVCheckBlock);
2069
2070 DT->addNewBlock(SCEVCheckBlock, Pred);
2071 DT->changeImmediateDominator(LoopVectorPreHeader, SCEVCheckBlock);
2072
2073 ReplaceInstWithInst(
2074 SCEVCheckBlock->getTerminator(),
2075 BranchInst::Create(Bypass, LoopVectorPreHeader, SCEVCheckCond));
2076 // Mark the check as used, to prevent it from being removed during cleanup.
2077 SCEVCheckCond = nullptr;
2078 return SCEVCheckBlock;
2079 }
2080
2081 /// Adds the generated MemCheckBlock before \p LoopVectorPreHeader and adjusts
2082 /// the branches to branch to the vector preheader or \p Bypass, depending on
2083 /// the generated condition.
2084 BasicBlock *emitMemRuntimeChecks(Loop *L, BasicBlock *Bypass,
2085 BasicBlock *LoopVectorPreHeader) {
2086 // Check if we generated code that checks in runtime if arrays overlap.
2087 if (!MemRuntimeCheckCond)
2088 return nullptr;
2089
2090 auto *Pred = LoopVectorPreHeader->getSinglePredecessor();
2091 Pred->getTerminator()->replaceSuccessorWith(LoopVectorPreHeader,
2092 MemCheckBlock);
2093
2094 DT->addNewBlock(MemCheckBlock, Pred);
2095 DT->changeImmediateDominator(LoopVectorPreHeader, MemCheckBlock);
2096 MemCheckBlock->moveBefore(LoopVectorPreHeader);
2097
2098 if (auto *PL = LI->getLoopFor(LoopVectorPreHeader))
2099 PL->addBasicBlockToLoop(MemCheckBlock, *LI);
2100
2101 ReplaceInstWithInst(
2102 MemCheckBlock->getTerminator(),
2103 BranchInst::Create(Bypass, LoopVectorPreHeader, MemRuntimeCheckCond));
2104 MemCheckBlock->getTerminator()->setDebugLoc(
2105 Pred->getTerminator()->getDebugLoc());
2106
2107 // Mark the check as used, to prevent it from being removed during cleanup.
2108 MemRuntimeCheckCond = nullptr;
2109 return MemCheckBlock;
2110 }
2111};
2112
2113// Return true if \p OuterLp is an outer loop annotated with hints for explicit
2114// vectorization. The loop needs to be annotated with #pragma omp simd
2115// simdlen(#) or #pragma clang vectorize(enable) vectorize_width(#). If the
2116// vector length information is not provided, vectorization is not considered
2117// explicit. Interleave hints are not allowed either. These limitations will be
2118// relaxed in the future.
2119// Please, note that we are currently forced to abuse the pragma 'clang
2120// vectorize' semantics. This pragma provides *auto-vectorization hints*
2121// (i.e., LV must check that vectorization is legal) whereas pragma 'omp simd'
2122// provides *explicit vectorization hints* (LV can bypass legal checks and
2123// assume that vectorization is legal). However, both hints are implemented
2124// using the same metadata (llvm.loop.vectorize, processed by
2125// LoopVectorizeHints). This will be fixed in the future when the native IR
2126// representation for pragma 'omp simd' is introduced.
2127static bool isExplicitVecOuterLoop(Loop *OuterLp,
2128 OptimizationRemarkEmitter *ORE) {
2129 assert(!OuterLp->isInnermost() && "This is not an outer loop")((void)0);
2130 LoopVectorizeHints Hints(OuterLp, true /*DisableInterleaving*/, *ORE);
2131
2132 // Only outer loops with an explicit vectorization hint are supported.
2133 // Unannotated outer loops are ignored.
2134 if (Hints.getForce() == LoopVectorizeHints::FK_Undefined)
2135 return false;
2136
2137 Function *Fn = OuterLp->getHeader()->getParent();
2138 if (!Hints.allowVectorization(Fn, OuterLp,
2139 true /*VectorizeOnlyWhenForced*/)) {
2140 LLVM_DEBUG(dbgs() << "LV: Loop hints prevent outer loop vectorization.\n")do { } while (false);
2141 return false;
2142 }
2143
2144 if (Hints.getInterleave() > 1) {
2145 // TODO: Interleave support is future work.
2146 LLVM_DEBUG(dbgs() << "LV: Not vectorizing: Interleave is not supported for "do { } while (false)
2147 "outer loops.\n")do { } while (false);
2148 Hints.emitRemarkWithHints();
2149 return false;
2150 }
2151
2152 return true;
2153}
2154
2155static void collectSupportedLoops(Loop &L, LoopInfo *LI,
2156 OptimizationRemarkEmitter *ORE,
2157 SmallVectorImpl<Loop *> &V) {
2158 // Collect inner loops and outer loops without irreducible control flow. For
2159 // now, only collect outer loops that have explicit vectorization hints. If we
2160 // are stress testing the VPlan H-CFG construction, we collect the outermost
2161 // loop of every loop nest.
2162 if (L.isInnermost() || VPlanBuildStressTest ||
2163 (EnableVPlanNativePath && isExplicitVecOuterLoop(&L, ORE))) {
2164 LoopBlocksRPO RPOT(&L);
2165 RPOT.perform(LI);
2166 if (!containsIrreducibleCFG<const BasicBlock *>(RPOT, *LI)) {
2167 V.push_back(&L);
2168 // TODO: Collect inner loops inside marked outer loops in case
2169 // vectorization fails for the outer loop. Do not invoke
2170 // 'containsIrreducibleCFG' again for inner loops when the outer loop is
2171 // already known to be reducible. We can use an inherited attribute for
2172 // that.
2173 return;
2174 }
2175 }
2176 for (Loop *InnerL : L)
2177 collectSupportedLoops(*InnerL, LI, ORE, V);
2178}
2179
2180namespace {
2181
2182/// The LoopVectorize Pass.
2183struct LoopVectorize : public FunctionPass {
2184 /// Pass identification, replacement for typeid
2185 static char ID;
2186
2187 LoopVectorizePass Impl;
2188
2189 explicit LoopVectorize(bool InterleaveOnlyWhenForced = false,
2190 bool VectorizeOnlyWhenForced = false)
2191 : FunctionPass(ID),
2192 Impl({InterleaveOnlyWhenForced, VectorizeOnlyWhenForced}) {
2193 initializeLoopVectorizePass(*PassRegistry::getPassRegistry());
2194 }
2195
2196 bool runOnFunction(Function &F) override {
2197 if (skipFunction(F))
2198 return false;
2199
2200 auto *SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
2201 auto *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
2202 auto *TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
2203 auto *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2204 auto *BFI = &getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI();
2205 auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
2206 auto *TLI = TLIP ? &TLIP->getTLI(F) : nullptr;
2207 auto *AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
2208 auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
2209 auto *LAA = &getAnalysis<LoopAccessLegacyAnalysis>();
2210 auto *DB = &getAnalysis<DemandedBitsWrapperPass>().getDemandedBits();
2211 auto *ORE = &getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
2212 auto *PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
2213
2214 std::function<const LoopAccessInfo &(Loop &)> GetLAA =
2215 [&](Loop &L) -> const LoopAccessInfo & { return LAA->getInfo(&L); };
2216
2217 return Impl.runImpl(F, *SE, *LI, *TTI, *DT, *BFI, TLI, *DB, *AA, *AC,
2218 GetLAA, *ORE, PSI).MadeAnyChange;
2219 }
2220
2221 void getAnalysisUsage(AnalysisUsage &AU) const override {
2222 AU.addRequired<AssumptionCacheTracker>();
2223 AU.addRequired<BlockFrequencyInfoWrapperPass>();
2224 AU.addRequired<DominatorTreeWrapperPass>();
2225 AU.addRequired<LoopInfoWrapperPass>();
2226 AU.addRequired<ScalarEvolutionWrapperPass>();
2227 AU.addRequired<TargetTransformInfoWrapperPass>();
2228 AU.addRequired<AAResultsWrapperPass>();
2229 AU.addRequired<LoopAccessLegacyAnalysis>();
2230 AU.addRequired<DemandedBitsWrapperPass>();
2231 AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
2232 AU.addRequired<InjectTLIMappingsLegacy>();
2233
2234 // We currently do not preserve loopinfo/dominator analyses with outer loop
2235 // vectorization. Until this is addressed, mark these analyses as preserved
2236 // only for non-VPlan-native path.
2237 // TODO: Preserve Loop and Dominator analyses for VPlan-native path.
2238 if (!EnableVPlanNativePath) {
2239 AU.addPreserved<LoopInfoWrapperPass>();
2240 AU.addPreserved<DominatorTreeWrapperPass>();
2241 }
2242
2243 AU.addPreserved<BasicAAWrapperPass>();
2244 AU.addPreserved<GlobalsAAWrapperPass>();
2245 AU.addRequired<ProfileSummaryInfoWrapperPass>();
2246 }
2247};
2248
2249} // end anonymous namespace
2250
2251//===----------------------------------------------------------------------===//
2252// Implementation of LoopVectorizationLegality, InnerLoopVectorizer and
2253// LoopVectorizationCostModel and LoopVectorizationPlanner.
2254//===----------------------------------------------------------------------===//
2255
2256Value *InnerLoopVectorizer::getBroadcastInstrs(Value *V) {
2257 // We need to place the broadcast of invariant variables outside the loop,
2258 // but only if it's proven safe to do so. Else, broadcast will be inside
2259 // vector loop body.
2260 Instruction *Instr = dyn_cast<Instruction>(V);
2261 bool SafeToHoist = OrigLoop->isLoopInvariant(V) &&
2262 (!Instr ||
2263 DT->dominates(Instr->getParent(), LoopVectorPreHeader));
2264 // Place the code for broadcasting invariant variables in the new preheader.
2265 IRBuilder<>::InsertPointGuard Guard(Builder);
2266 if (SafeToHoist)
2267 Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
2268
2269 // Broadcast the scalar into all locations in the vector.
2270 Value *Shuf = Builder.CreateVectorSplat(VF, V, "broadcast");
2271
2272 return Shuf;
2273}
2274
2275void InnerLoopVectorizer::createVectorIntOrFpInductionPHI(
2276 const InductionDescriptor &II, Value *Step, Value *Start,
2277 Instruction *EntryVal, VPValue *Def, VPValue *CastDef,
2278 VPTransformState &State) {
2279 assert((isa<PHINode>(EntryVal) || isa<TruncInst>(EntryVal)) &&((void)0)
2280 "Expected either an induction phi-node or a truncate of it!")((void)0);
2281
2282 // Construct the initial value of the vector IV in the vector loop preheader
2283 auto CurrIP = Builder.saveIP();
2284 Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
2285 if (isa<TruncInst>(EntryVal)) {
2286 assert(Start->getType()->isIntegerTy() &&((void)0)
2287 "Truncation requires an integer type")((void)0);
2288 auto *TruncType = cast<IntegerType>(EntryVal->getType());
2289 Step = Builder.CreateTrunc(Step, TruncType);
2290 Start = Builder.CreateCast(Instruction::Trunc, Start, TruncType);
2291 }
2292 Value *SplatStart = Builder.CreateVectorSplat(VF, Start);
2293 Value *SteppedStart =
2294 getStepVector(SplatStart, 0, Step, II.getInductionOpcode());
2295
2296 // We create vector phi nodes for both integer and floating-point induction
2297 // variables. Here, we determine the kind of arithmetic we will perform.
2298 Instruction::BinaryOps AddOp;
2299 Instruction::BinaryOps MulOp;
2300 if (Step->getType()->isIntegerTy()) {
2301 AddOp = Instruction::Add;
2302 MulOp = Instruction::Mul;
2303 } else {
2304 AddOp = II.getInductionOpcode();
2305 MulOp = Instruction::FMul;
2306 }
2307
2308 // Multiply the vectorization factor by the step using integer or
2309 // floating-point arithmetic as appropriate.
2310 Type *StepType = Step->getType();
2311 if (Step->getType()->isFloatingPointTy())
2312 StepType = IntegerType::get(StepType->getContext(),
2313 StepType->getScalarSizeInBits());
2314 Value *RuntimeVF = getRuntimeVF(Builder, StepType, VF);
2315 if (Step->getType()->isFloatingPointTy())
2316 RuntimeVF = Builder.CreateSIToFP(RuntimeVF, Step->getType());
2317 Value *Mul = Builder.CreateBinOp(MulOp, Step, RuntimeVF);
2318
2319 // Create a vector splat to use in the induction update.
2320 //
2321 // FIXME: If the step is non-constant, we create the vector splat with
2322 // IRBuilder. IRBuilder can constant-fold the multiply, but it doesn't
2323 // handle a constant vector splat.
2324 Value *SplatVF = isa<Constant>(Mul)
2325 ? ConstantVector::getSplat(VF, cast<Constant>(Mul))
2326 : Builder.CreateVectorSplat(VF, Mul);
2327 Builder.restoreIP(CurrIP);
2328
2329 // We may need to add the step a number of times, depending on the unroll
2330 // factor. The last of those goes into the PHI.
2331 PHINode *VecInd = PHINode::Create(SteppedStart->getType(), 2, "vec.ind",
2332 &*LoopVectorBody->getFirstInsertionPt());
2333 VecInd->setDebugLoc(EntryVal->getDebugLoc());
2334 Instruction *LastInduction = VecInd;
2335 for (unsigned Part = 0; Part < UF; ++Part) {
2336 State.set(Def, LastInduction, Part);
2337
2338 if (isa<TruncInst>(EntryVal))
2339 addMetadata(LastInduction, EntryVal);
2340 recordVectorLoopValueForInductionCast(II, EntryVal, LastInduction, CastDef,
2341 State, Part);
2342
2343 LastInduction = cast<Instruction>(
2344 Builder.CreateBinOp(AddOp, LastInduction, SplatVF, "step.add"));
2345 LastInduction->setDebugLoc(EntryVal->getDebugLoc());
2346 }
2347
2348 // Move the last step to the end of the latch block. This ensures consistent
2349 // placement of all induction updates.
2350 auto *LoopVectorLatch = LI->getLoopFor(LoopVectorBody)->getLoopLatch();
2351 auto *Br = cast<BranchInst>(LoopVectorLatch->getTerminator());
2352 auto *ICmp = cast<Instruction>(Br->getCondition());
2353 LastInduction->moveBefore(ICmp);
2354 LastInduction->setName("vec.ind.next");
2355
2356 VecInd->addIncoming(SteppedStart, LoopVectorPreHeader);
2357 VecInd->addIncoming(LastInduction, LoopVectorLatch);
2358}
2359
2360bool InnerLoopVectorizer::shouldScalarizeInstruction(Instruction *I) const {
2361 return Cost->isScalarAfterVectorization(I, VF) ||
2362 Cost->isProfitableToScalarize(I, VF);
2363}
2364
2365bool InnerLoopVectorizer::needsScalarInduction(Instruction *IV) const {
2366 if (shouldScalarizeInstruction(IV))
2367 return true;
2368 auto isScalarInst = [&](User *U) -> bool {
2369 auto *I = cast<Instruction>(U);
2370 return (OrigLoop->contains(I) && shouldScalarizeInstruction(I));
2371 };
2372 return llvm::any_of(IV->users(), isScalarInst);
2373}
2374
2375void InnerLoopVectorizer::recordVectorLoopValueForInductionCast(
2376 const InductionDescriptor &ID, const Instruction *EntryVal,
2377 Value *VectorLoopVal, VPValue *CastDef, VPTransformState &State,
2378 unsigned Part, unsigned Lane) {
2379 assert((isa<PHINode>(EntryVal) || isa<TruncInst>(EntryVal)) &&((void)0)
2380 "Expected either an induction phi-node or a truncate of it!")((void)0);
2381
2382 // This induction variable is not the phi from the original loop but the
2383 // newly-created IV based on the proof that casted Phi is equal to the
2384 // uncasted Phi in the vectorized loop (under a runtime guard possibly). It
2385 // re-uses the same InductionDescriptor that original IV uses but we don't
2386 // have to do any recording in this case - that is done when original IV is
2387 // processed.
2388 if (isa<TruncInst>(EntryVal))
2389 return;
2390
2391 const SmallVectorImpl<Instruction *> &Casts = ID.getCastInsts();
2392 if (Casts.empty())
2393 return;
2394 // Only the first Cast instruction in the Casts vector is of interest.
2395 // The rest of the Casts (if exist) have no uses outside the
2396 // induction update chain itself.
2397 if (Lane < UINT_MAX(2147483647 *2U +1U))
2398 State.set(CastDef, VectorLoopVal, VPIteration(Part, Lane));
2399 else
2400 State.set(CastDef, VectorLoopVal, Part);
2401}
2402
2403void InnerLoopVectorizer::widenIntOrFpInduction(PHINode *IV, Value *Start,
2404 TruncInst *Trunc, VPValue *Def,
2405 VPValue *CastDef,
2406 VPTransformState &State) {
2407 assert((IV->getType()->isIntegerTy() || IV != OldInduction) &&((void)0)
2408 "Primary induction variable must have an integer type")((void)0);
2409
2410 auto II = Legal->getInductionVars().find(IV);
2411 assert(II != Legal->getInductionVars().end() && "IV is not an induction")((void)0);
2412
2413 auto ID = II->second;
2414 assert(IV->getType() == ID.getStartValue()->getType() && "Types must match")((void)0);
2415
2416 // The value from the original loop to which we are mapping the new induction
2417 // variable.
2418 Instruction *EntryVal = Trunc ? cast<Instruction>(Trunc) : IV;
2419
2420 auto &DL = OrigLoop->getHeader()->getModule()->getDataLayout();
2421
2422 // Generate code for the induction step. Note that induction steps are
2423 // required to be loop-invariant
2424 auto CreateStepValue = [&](const SCEV *Step) -> Value * {
2425 assert(PSE.getSE()->isLoopInvariant(Step, OrigLoop) &&((void)0)
2426 "Induction step should be loop invariant")((void)0);
2427 if (PSE.getSE()->isSCEVable(IV->getType())) {
2428 SCEVExpander Exp(*PSE.getSE(), DL, "induction");
2429 return Exp.expandCodeFor(Step, Step->getType(),
2430 LoopVectorPreHeader->getTerminator());
2431 }
2432 return cast<SCEVUnknown>(Step)->getValue();
2433 };
2434
2435 // The scalar value to broadcast. This is derived from the canonical
2436 // induction variable. If a truncation type is given, truncate the canonical
2437 // induction variable and step. Otherwise, derive these values from the
2438 // induction descriptor.
2439 auto CreateScalarIV = [&](Value *&Step) -> Value * {
2440 Value *ScalarIV = Induction;
2441 if (IV != OldInduction) {
2442 ScalarIV = IV->getType()->isIntegerTy()
2443 ? Builder.CreateSExtOrTrunc(Induction, IV->getType())
2444 : Builder.CreateCast(Instruction::SIToFP, Induction,
2445 IV->getType());
2446 ScalarIV = emitTransformedIndex(Builder, ScalarIV, PSE.getSE(), DL, ID);
2447 ScalarIV->setName("offset.idx");
2448 }
2449 if (Trunc) {
2450 auto *TruncType = cast<IntegerType>(Trunc->getType());
2451 assert(Step->getType()->isIntegerTy() &&((void)0)
2452 "Truncation requires an integer step")((void)0);
2453 ScalarIV = Builder.CreateTrunc(ScalarIV, TruncType);
2454 Step = Builder.CreateTrunc(Step, TruncType);
2455 }
2456 return ScalarIV;
2457 };
2458
2459 // Create the vector values from the scalar IV, in the absence of creating a
2460 // vector IV.
2461 auto CreateSplatIV = [&](Value *ScalarIV, Value *Step) {
2462 Value *Broadcasted = getBroadcastInstrs(ScalarIV);
2463 for (unsigned Part = 0; Part < UF; ++Part) {
2464 assert(!VF.isScalable() && "scalable vectors not yet supported.")((void)0);
2465 Value *EntryPart =
2466 getStepVector(Broadcasted, VF.getKnownMinValue() * Part, Step,
2467 ID.getInductionOpcode());
2468 State.set(Def, EntryPart, Part);
2469 if (Trunc)
2470 addMetadata(EntryPart, Trunc);
2471 recordVectorLoopValueForInductionCast(ID, EntryVal, EntryPart, CastDef,
2472 State, Part);
2473 }
2474 };
2475
2476 // Fast-math-flags propagate from the original induction instruction.
2477 IRBuilder<>::FastMathFlagGuard FMFG(Builder);
2478 if (ID.getInductionBinOp() && isa<FPMathOperator>(ID.getInductionBinOp()))
2479 Builder.setFastMathFlags(ID.getInductionBinOp()->getFastMathFlags());
2480
2481 // Now do the actual transformations, and start with creating the step value.
2482 Value *Step = CreateStepValue(ID.getStep());
2483 if (VF.isZero() || VF.isScalar()) {
2484 Value *ScalarIV = CreateScalarIV(Step);
2485 CreateSplatIV(ScalarIV, Step);
2486 return;
2487 }
2488
2489 // Determine if we want a scalar version of the induction variable. This is
2490 // true if the induction variable itself is not widened, or if it has at
2491 // least one user in the loop that is not widened.
2492 auto NeedsScalarIV = needsScalarInduction(EntryVal);
2493 if (!NeedsScalarIV) {
2494 createVectorIntOrFpInductionPHI(ID, Step, Start, EntryVal, Def, CastDef,
2495 State);
2496 return;
2497 }
2498
2499 // Try to create a new independent vector induction variable. If we can't
2500 // create the phi node, we will splat the scalar induction variable in each
2501 // loop iteration.
2502 if (!shouldScalarizeInstruction(EntryVal)) {
2503 createVectorIntOrFpInductionPHI(ID, Step, Start, EntryVal, Def, CastDef,
2504 State);
2505 Value *ScalarIV = CreateScalarIV(Step);
2506 // Create scalar steps that can be used by instructions we will later
2507 // scalarize. Note that the addition of the scalar steps will not increase
2508 // the number of instructions in the loop in the common case prior to
2509 // InstCombine. We will be trading one vector extract for each scalar step.
2510 buildScalarSteps(ScalarIV, Step, EntryVal, ID, Def, CastDef, State);
2511 return;
2512 }
2513
2514 // All IV users are scalar instructions, so only emit a scalar IV, not a
2515 // vectorised IV. Except when we tail-fold, then the splat IV feeds the
2516 // predicate used by the masked loads/stores.
2517 Value *ScalarIV = CreateScalarIV(Step);
2518 if (!Cost->isScalarEpilogueAllowed())
2519 CreateSplatIV(ScalarIV, Step);
2520 buildScalarSteps(ScalarIV, Step, EntryVal, ID, Def, CastDef, State);
2521}
2522
2523Value *InnerLoopVectorizer::getStepVector(Value *Val, int StartIdx, Value *Step,
2524 Instruction::BinaryOps BinOp) {
2525 // Create and check the types.
2526 auto *ValVTy = cast<VectorType>(Val->getType());
2527 ElementCount VLen = ValVTy->getElementCount();
2528
2529 Type *STy = Val->getType()->getScalarType();
2530 assert((STy->isIntegerTy() || STy->isFloatingPointTy()) &&((void)0)
2531 "Induction Step must be an integer or FP")((void)0);
2532 assert(Step->getType() == STy && "Step has wrong type")((void)0);
2533
2534 SmallVector<Constant *, 8> Indices;
2535
2536 // Create a vector of consecutive numbers from zero to VF.
2537 VectorType *InitVecValVTy = ValVTy;
2538 Type *InitVecValSTy = STy;
2539 if (STy->isFloatingPointTy()) {
2540 InitVecValSTy =
2541 IntegerType::get(STy->getContext(), STy->getScalarSizeInBits());
2542 InitVecValVTy = VectorType::get(InitVecValSTy, VLen);
2543 }
2544 Value *InitVec = Builder.CreateStepVector(InitVecValVTy);
2545
2546 // Add on StartIdx
2547 Value *StartIdxSplat = Builder.CreateVectorSplat(
2548 VLen, ConstantInt::get(InitVecValSTy, StartIdx));
2549 InitVec = Builder.CreateAdd(InitVec, StartIdxSplat);
2550
2551 if (STy->isIntegerTy()) {
2552 Step = Builder.CreateVectorSplat(VLen, Step);
2553 assert(Step->getType() == Val->getType() && "Invalid step vec")((void)0);
2554 // FIXME: The newly created binary instructions should contain nsw/nuw flags,
2555 // which can be found from the original scalar operations.
2556 Step = Builder.CreateMul(InitVec, Step);
2557 return Builder.CreateAdd(Val, Step, "induction");
2558 }
2559
2560 // Floating point induction.
2561 assert((BinOp == Instruction::FAdd || BinOp == Instruction::FSub) &&((void)0)
2562 "Binary Opcode should be specified for FP induction")((void)0);
2563 InitVec = Builder.CreateUIToFP(InitVec, ValVTy);
2564 Step = Builder.CreateVectorSplat(VLen, Step);
2565 Value *MulOp = Builder.CreateFMul(InitVec, Step);
2566 return Builder.CreateBinOp(BinOp, Val, MulOp, "induction");
2567}
2568
2569void InnerLoopVectorizer::buildScalarSteps(Value *ScalarIV, Value *Step,
2570 Instruction *EntryVal,
2571 const InductionDescriptor &ID,
2572 VPValue *Def, VPValue *CastDef,
2573 VPTransformState &State) {
2574 // We shouldn't have to build scalar steps if we aren't vectorizing.
2575 assert(VF.isVector() && "VF should be greater than one")((void)0);
2576 // Get the value type and ensure it and the step have the same integer type.
2577 Type *ScalarIVTy = ScalarIV->getType()->getScalarType();
2578 assert(ScalarIVTy == Step->getType() &&((void)0)
2579 "Val and Step should have the same type")((void)0);
2580
2581 // We build scalar steps for both integer and floating-point induction
2582 // variables. Here, we determine the kind of arithmetic we will perform.
2583 Instruction::BinaryOps AddOp;
2584 Instruction::BinaryOps MulOp;
2585 if (ScalarIVTy->isIntegerTy()) {
2586 AddOp = Instruction::Add;
2587 MulOp = Instruction::Mul;
2588 } else {
2589 AddOp = ID.getInductionOpcode();
2590 MulOp = Instruction::FMul;
2591 }
2592
2593 // Determine the number of scalars we need to generate for each unroll
2594 // iteration. If EntryVal is uniform, we only need to generate the first
2595 // lane. Otherwise, we generate all VF values.
2596 bool IsUniform =
2597 Cost->isUniformAfterVectorization(cast<Instruction>(EntryVal), VF);
2598 unsigned Lanes = IsUniform ? 1 : VF.getKnownMinValue();
2599 // Compute the scalar steps and save the results in State.
2600 Type *IntStepTy = IntegerType::get(ScalarIVTy->getContext(),
2601 ScalarIVTy->getScalarSizeInBits());
2602 Type *VecIVTy = nullptr;
2603 Value *UnitStepVec = nullptr, *SplatStep = nullptr, *SplatIV = nullptr;
2604 if (!IsUniform && VF.isScalable()) {
2605 VecIVTy = VectorType::get(ScalarIVTy, VF);
2606 UnitStepVec = Builder.CreateStepVector(VectorType::get(IntStepTy, VF));
2607 SplatStep = Builder.CreateVectorSplat(VF, Step);
2608 SplatIV = Builder.CreateVectorSplat(VF, ScalarIV);
2609 }
2610
2611 for (unsigned Part = 0; Part < UF; ++Part) {
2612 Value *StartIdx0 =
2613 createStepForVF(Builder, ConstantInt::get(IntStepTy, Part), VF);
2614
2615 if (!IsUniform && VF.isScalable()) {
2616 auto *SplatStartIdx = Builder.CreateVectorSplat(VF, StartIdx0);
2617 auto *InitVec = Builder.CreateAdd(SplatStartIdx, UnitStepVec);
2618 if (ScalarIVTy->isFloatingPointTy())
2619 InitVec = Builder.CreateSIToFP(InitVec, VecIVTy);
2620 auto *Mul = Builder.CreateBinOp(MulOp, InitVec, SplatStep);
2621 auto *Add = Builder.CreateBinOp(AddOp, SplatIV, Mul);
2622 State.set(Def, Add, Part);
2623 recordVectorLoopValueForInductionCast(ID, EntryVal, Add, CastDef, State,
2624 Part);
2625 // It's useful to record the lane values too for the known minimum number
2626 // of elements so we do those below. This improves the code quality when
2627 // trying to extract the first element, for example.
2628 }
2629
2630 if (ScalarIVTy->isFloatingPointTy())
2631 StartIdx0 = Builder.CreateSIToFP(StartIdx0, ScalarIVTy);
2632
2633 for (unsigned Lane = 0; Lane < Lanes; ++Lane) {
2634 Value *StartIdx = Builder.CreateBinOp(
2635 AddOp, StartIdx0, getSignedIntOrFpConstant(ScalarIVTy, Lane));
2636 // The step returned by `createStepForVF` is a runtime-evaluated value
2637 // when VF is scalable. Otherwise, it should be folded into a Constant.
2638 assert((VF.isScalable() || isa<Constant>(StartIdx)) &&((void)0)
2639 "Expected StartIdx to be folded to a constant when VF is not "((void)0)
2640 "scalable")((void)0);
2641 auto *Mul = Builder.CreateBinOp(MulOp, StartIdx, Step);
2642 auto *Add = Builder.CreateBinOp(AddOp, ScalarIV, Mul);
2643 State.set(Def, Add, VPIteration(Part, Lane));
2644 recordVectorLoopValueForInductionCast(ID, EntryVal, Add, CastDef, State,
2645 Part, Lane);
2646 }
2647 }
2648}
2649
2650void InnerLoopVectorizer::packScalarIntoVectorValue(VPValue *Def,
2651 const VPIteration &Instance,
2652 VPTransformState &State) {
2653 Value *ScalarInst = State.get(Def, Instance);
2654 Value *VectorValue = State.get(Def, Instance.Part);
2655 VectorValue = Builder.CreateInsertElement(
2656 VectorValue, ScalarInst,
2657 Instance.Lane.getAsRuntimeExpr(State.Builder, VF));
2658 State.set(Def, VectorValue, Instance.Part);
2659}
2660
2661Value *InnerLoopVectorizer::reverseVector(Value *Vec) {
2662 assert(Vec->getType()->isVectorTy() && "Invalid type")((void)0);
2663 return Builder.CreateVectorReverse(Vec, "reverse");
2664}
2665
2666// Return whether we allow using masked interleave-groups (for dealing with
2667// strided loads/stores that reside in predicated blocks, or for dealing
2668// with gaps).
2669static bool useMaskedInterleavedAccesses(const TargetTransformInfo &TTI) {
2670 // If an override option has been passed in for interleaved accesses, use it.
2671 if (EnableMaskedInterleavedMemAccesses.getNumOccurrences() > 0)
2672 return EnableMaskedInterleavedMemAccesses;
2673
2674 return TTI.enableMaskedInterleavedAccessVectorization();
2675}
2676
2677// Try to vectorize the interleave group that \p Instr belongs to.
2678//
2679// E.g. Translate following interleaved load group (factor = 3):
2680// for (i = 0; i < N; i+=3) {
2681// R = Pic[i]; // Member of index 0
2682// G = Pic[i+1]; // Member of index 1
2683// B = Pic[i+2]; // Member of index 2
2684// ... // do something to R, G, B
2685// }
2686// To:
2687// %wide.vec = load <12 x i32> ; Read 4 tuples of R,G,B
2688// %R.vec = shuffle %wide.vec, poison, <0, 3, 6, 9> ; R elements
2689// %G.vec = shuffle %wide.vec, poison, <1, 4, 7, 10> ; G elements
2690// %B.vec = shuffle %wide.vec, poison, <2, 5, 8, 11> ; B elements
2691//
2692// Or translate following interleaved store group (factor = 3):
2693// for (i = 0; i < N; i+=3) {
2694// ... do something to R, G, B
2695// Pic[i] = R; // Member of index 0
2696// Pic[i+1] = G; // Member of index 1
2697// Pic[i+2] = B; // Member of index 2
2698// }
2699// To:
2700// %R_G.vec = shuffle %R.vec, %G.vec, <0, 1, 2, ..., 7>
2701// %B_U.vec = shuffle %B.vec, poison, <0, 1, 2, 3, u, u, u, u>
2702// %interleaved.vec = shuffle %R_G.vec, %B_U.vec,
2703// <0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11> ; Interleave R,G,B elements
2704// store <12 x i32> %interleaved.vec ; Write 4 tuples of R,G,B
2705void InnerLoopVectorizer::vectorizeInterleaveGroup(
2706 const InterleaveGroup<Instruction> *Group, ArrayRef<VPValue *> VPDefs,
2707 VPTransformState &State, VPValue *Addr, ArrayRef<VPValue *> StoredValues,
2708 VPValue *BlockInMask) {
2709 Instruction *Instr = Group->getInsertPos();
2710 const DataLayout &DL = Instr->getModule()->getDataLayout();
2711
2712 // Prepare for the vector type of the interleaved load/store.
2713 Type *ScalarTy = getLoadStoreType(Instr);
2714 unsigned InterleaveFactor = Group->getFactor();
2715 assert(!VF.isScalable() && "scalable vectors not yet supported.")((void)0);
2716 auto *VecTy = VectorType::get(ScalarTy, VF * InterleaveFactor);
2717
2718 // Prepare for the new pointers.
2719 SmallVector<Value *, 2> AddrParts;
2720 unsigned Index = Group->getIndex(Instr);
2721
2722 // TODO: extend the masked interleaved-group support to reversed access.
2723 assert((!BlockInMask || !Group->isReverse()) &&((void)0)
2724 "Reversed masked interleave-group not supported.")((void)0);
2725
2726 // If the group is reverse, adjust the index to refer to the last vector lane
2727 // instead of the first. We adjust the index from the first vector lane,
2728 // rather than directly getting the pointer for lane VF - 1, because the
2729 // pointer operand of the interleaved access is supposed to be uniform. For
2730 // uniform instructions, we're only required to generate a value for the
2731 // first vector lane in each unroll iteration.
2732 if (Group->isReverse())
2733 Index += (VF.getKnownMinValue() - 1) * Group->getFactor();
2734
2735 for (unsigned Part = 0; Part < UF; Part++) {
2736 Value *AddrPart = State.get(Addr, VPIteration(Part, 0));
2737 setDebugLocFromInst(AddrPart);
2738
2739 // Notice current instruction could be any index. Need to adjust the address
2740 // to the member of index 0.
2741 //
2742 // E.g. a = A[i+1]; // Member of index 1 (Current instruction)
2743 // b = A[i]; // Member of index 0
2744 // Current pointer is pointed to A[i+1], adjust it to A[i].
2745 //
2746 // E.g. A[i+1] = a; // Member of index 1
2747 // A[i] = b; // Member of index 0
2748 // A[i+2] = c; // Member of index 2 (Current instruction)
2749 // Current pointer is pointed to A[i+2], adjust it to A[i].
2750
2751 bool InBounds = false;
2752 if (auto *gep = dyn_cast<GetElementPtrInst>(AddrPart->stripPointerCasts()))
2753 InBounds = gep->isInBounds();
2754 AddrPart = Builder.CreateGEP(ScalarTy, AddrPart, Builder.getInt32(-Index));
2755 cast<GetElementPtrInst>(AddrPart)->setIsInBounds(InBounds);
2756
2757 // Cast to the vector pointer type.
2758 unsigned AddressSpace = AddrPart->getType()->getPointerAddressSpace();
2759 Type *PtrTy = VecTy->getPointerTo(AddressSpace);
2760 AddrParts.push_back(Builder.CreateBitCast(AddrPart, PtrTy));
2761 }
2762
2763 setDebugLocFromInst(Instr);
2764 Value *PoisonVec = PoisonValue::get(VecTy);
2765
2766 Value *MaskForGaps = nullptr;
2767 if (Group->requiresScalarEpilogue() && !Cost->isScalarEpilogueAllowed()) {
2768 MaskForGaps = createBitMaskForGaps(Builder, VF.getKnownMinValue(), *Group);
2769 assert(MaskForGaps && "Mask for Gaps is required but it is null")((void)0);
2770 }
2771
2772 // Vectorize the interleaved load group.
2773 if (isa<LoadInst>(Instr)) {
2774 // For each unroll part, create a wide load for the group.
2775 SmallVector<Value *, 2> NewLoads;
2776 for (unsigned Part = 0; Part < UF; Part++) {
2777 Instruction *NewLoad;
2778 if (BlockInMask || MaskForGaps) {
2779 assert(useMaskedInterleavedAccesses(*TTI) &&((void)0)
2780 "masked interleaved groups are not allowed.")((void)0);
2781 Value *GroupMask = MaskForGaps;
2782 if (BlockInMask) {
2783 Value *BlockInMaskPart = State.get(BlockInMask, Part);
2784 Value *ShuffledMask = Builder.CreateShuffleVector(
2785 BlockInMaskPart,
2786 createReplicatedMask(InterleaveFactor, VF.getKnownMinValue()),
2787 "interleaved.mask");
2788 GroupMask = MaskForGaps
2789 ? Builder.CreateBinOp(Instruction::And, ShuffledMask,
2790 MaskForGaps)
2791 : ShuffledMask;
2792 }
2793 NewLoad =
2794 Builder.CreateMaskedLoad(VecTy, AddrParts[Part], Group->getAlign(),
2795 GroupMask, PoisonVec, "wide.masked.vec");
2796 }
2797 else
2798 NewLoad = Builder.CreateAlignedLoad(VecTy, AddrParts[Part],
2799 Group->getAlign(), "wide.vec");
2800 Group->addMetadata(NewLoad);
2801 NewLoads.push_back(NewLoad);
2802 }
2803
2804 // For each member in the group, shuffle out the appropriate data from the
2805 // wide loads.
2806 unsigned J = 0;
2807 for (unsigned I = 0; I < InterleaveFactor; ++I) {
2808 Instruction *Member = Group->getMember(I);
2809
2810 // Skip the gaps in the group.
2811 if (!Member)
2812 continue;
2813
2814 auto StrideMask =
2815 createStrideMask(I, InterleaveFactor, VF.getKnownMinValue());
2816 for (unsigned Part = 0; Part < UF; Part++) {
2817 Value *StridedVec = Builder.CreateShuffleVector(
2818 NewLoads[Part], StrideMask, "strided.vec");
2819
2820 // If this member has different type, cast the result type.
2821 if (Member->getType() != ScalarTy) {
2822 assert(!VF.isScalable() && "VF is assumed to be non scalable.")((void)0);
2823 VectorType *OtherVTy = VectorType::get(Member->getType(), VF);
2824 StridedVec = createBitOrPointerCast(StridedVec, OtherVTy, DL);
2825 }
2826
2827 if (Group->isReverse())
2828 StridedVec = reverseVector(StridedVec);
2829
2830 State.set(VPDefs[J], StridedVec, Part);
2831 }
2832 ++J;
2833 }
2834 return;
2835 }
2836
2837 // The sub vector type for current instruction.
2838 auto *SubVT = VectorType::get(ScalarTy, VF);
2839
2840 // Vectorize the interleaved store group.
2841 for (unsigned Part = 0; Part < UF; Part++) {
2842 // Collect the stored vector from each member.
2843 SmallVector<Value *, 4> StoredVecs;
2844 for (unsigned i = 0; i < InterleaveFactor; i++) {
2845 // Interleaved store group doesn't allow a gap, so each index has a member
2846 assert(Group->getMember(i) && "Fail to get a member from an interleaved store group")((void)0);
2847
2848 Value *StoredVec = State.get(StoredValues[i], Part);
2849
2850 if (Group->isReverse())
2851 StoredVec = reverseVector(StoredVec);
2852
2853 // If this member has different type, cast it to a unified type.
2854
2855 if (StoredVec->getType() != SubVT)
2856 StoredVec = createBitOrPointerCast(StoredVec, SubVT, DL);
2857
2858 StoredVecs.push_back(StoredVec);
2859 }
2860
2861 // Concatenate all vectors into a wide vector.
2862 Value *WideVec = concatenateVectors(Builder, StoredVecs);
2863
2864 // Interleave the elements in the wide vector.
2865 Value *IVec = Builder.CreateShuffleVector(
2866 WideVec, createInterleaveMask(VF.getKnownMinValue(), InterleaveFactor),
2867 "interleaved.vec");
2868
2869 Instruction *NewStoreInstr;
2870 if (BlockInMask) {
2871 Value *BlockInMaskPart = State.get(BlockInMask, Part);
2872 Value *ShuffledMask = Builder.CreateShuffleVector(
2873 BlockInMaskPart,
2874 createReplicatedMask(InterleaveFactor, VF.getKnownMinValue()),
2875 "interleaved.mask");
2876 NewStoreInstr = Builder.CreateMaskedStore(
2877 IVec, AddrParts[Part], Group->getAlign(), ShuffledMask);
2878 }
2879 else
2880 NewStoreInstr =
2881 Builder.CreateAlignedStore(IVec, AddrParts[Part], Group->getAlign());
2882
2883 Group->addMetadata(NewStoreInstr);
2884 }
2885}
2886
2887void InnerLoopVectorizer::vectorizeMemoryInstruction(
2888 Instruction *Instr, VPTransformState &State, VPValue *Def, VPValue *Addr,
2889 VPValue *StoredValue, VPValue *BlockInMask) {
2890 // Attempt to issue a wide load.
2891 LoadInst *LI = dyn_cast<LoadInst>(Instr);
2892 StoreInst *SI = dyn_cast<StoreInst>(Instr);
2893
2894 assert((LI || SI) && "Invalid Load/Store instruction")((void)0);
2895 assert((!SI || StoredValue) && "No stored value provided for widened store")((void)0);
2896 assert((!LI || !StoredValue) && "Stored value provided for widened load")((void)0);
2897
2898 LoopVectorizationCostModel::InstWidening Decision =
2899 Cost->getWideningDecision(Instr, VF);
2900 assert((Decision == LoopVectorizationCostModel::CM_Widen ||((void)0)
2901 Decision == LoopVectorizationCostModel::CM_Widen_Reverse ||((void)0)
2902 Decision == LoopVectorizationCostModel::CM_GatherScatter) &&((void)0)
2903 "CM decision is not to widen the memory instruction")((void)0);
2904
2905 Type *ScalarDataTy = getLoadStoreType(Instr);
2906
2907 auto *DataTy = VectorType::get(ScalarDataTy, VF);
2908 const Align Alignment = getLoadStoreAlignment(Instr);
2909
2910 // Determine if the pointer operand of the access is either consecutive or
2911 // reverse consecutive.
2912 bool Reverse = (Decision == LoopVectorizationCostModel::CM_Widen_Reverse);
2913 bool ConsecutiveStride =
2914 Reverse || (Decision == LoopVectorizationCostModel::CM_Widen);
2915 bool CreateGatherScatter =
2916 (Decision == LoopVectorizationCostModel::CM_GatherScatter);
2917
2918 // Either Ptr feeds a vector load/store, or a vector GEP should feed a vector
2919 // gather/scatter. Otherwise Decision should have been to Scalarize.
2920 assert((ConsecutiveStride || CreateGatherScatter) &&((void)0)
2921 "The instruction should be scalarized")((void)0);
2922 (void)ConsecutiveStride;
2923
2924 VectorParts BlockInMaskParts(UF);
2925 bool isMaskRequired = BlockInMask;
2926 if (isMaskRequired)
2927 for (unsigned Part = 0; Part < UF; ++Part)
2928 BlockInMaskParts[Part] = State.get(BlockInMask, Part);
2929
2930 const auto CreateVecPtr = [&](unsigned Part, Value *Ptr) -> Value * {
2931 // Calculate the pointer for the specific unroll-part.
2932 GetElementPtrInst *PartPtr = nullptr;
2933
2934 bool InBounds = false;
2935 if (auto *gep = dyn_cast<GetElementPtrInst>(Ptr->stripPointerCasts()))
2936 InBounds = gep->isInBounds();
2937 if (Reverse) {
2938 // If the address is consecutive but reversed, then the
2939 // wide store needs to start at the last vector element.
2940 // RunTimeVF = VScale * VF.getKnownMinValue()
2941 // For fixed-width VScale is 1, then RunTimeVF = VF.getKnownMinValue()
2942 Value *RunTimeVF = getRuntimeVF(Builder, Builder.getInt32Ty(), VF);
2943 // NumElt = -Part * RunTimeVF
2944 Value *NumElt = Builder.CreateMul(Builder.getInt32(-Part), RunTimeVF);
2945 // LastLane = 1 - RunTimeVF
2946 Value *LastLane = Builder.CreateSub(Builder.getInt32(1), RunTimeVF);
2947 PartPtr =
2948 cast<GetElementPtrInst>(Builder.CreateGEP(ScalarDataTy, Ptr, NumElt));
2949 PartPtr->setIsInBounds(InBounds);
2950 PartPtr = cast<GetElementPtrInst>(
2951 Builder.CreateGEP(ScalarDataTy, PartPtr, LastLane));
2952 PartPtr->setIsInBounds(InBounds);
2953 if (isMaskRequired) // Reverse of a null all-one mask is a null mask.
2954 BlockInMaskParts[Part] = reverseVector(BlockInMaskParts[Part]);
2955 } else {
2956 Value *Increment = createStepForVF(Builder, Builder.getInt32(Part), VF);
2957 PartPtr = cast<GetElementPtrInst>(
2958 Builder.CreateGEP(ScalarDataTy, Ptr, Increment));
2959 PartPtr->setIsInBounds(InBounds);
2960 }
2961
2962 unsigned AddressSpace = Ptr->getType()->getPointerAddressSpace();
2963 return Builder.CreateBitCast(PartPtr, DataTy->getPointerTo(AddressSpace));
2964 };
2965
2966 // Handle Stores:
2967 if (SI) {
2968 setDebugLocFromInst(SI);
2969
2970 for (unsigned Part = 0; Part < UF; ++Part) {
2971 Instruction *NewSI = nullptr;
2972 Value *StoredVal = State.get(StoredValue, Part);
2973 if (CreateGatherScatter) {
2974 Value *MaskPart = isMaskRequired ? BlockInMaskParts[Part] : nullptr;
2975 Value *VectorGep = State.get(Addr, Part);
2976 NewSI = Builder.CreateMaskedScatter(StoredVal, VectorGep, Alignment,
2977 MaskPart);
2978 } else {
2979 if (Reverse) {
2980 // If we store to reverse consecutive memory locations, then we need
2981 // to reverse the order of elements in the stored value.
2982 StoredVal = reverseVector(StoredVal);
2983 // We don't want to update the value in the map as it might be used in
2984 // another expression. So don't call resetVectorValue(StoredVal).
2985 }
2986 auto *VecPtr = CreateVecPtr(Part, State.get(Addr, VPIteration(0, 0)));
2987 if (isMaskRequired)
2988 NewSI = Builder.CreateMaskedStore(StoredVal, VecPtr, Alignment,
2989 BlockInMaskParts[Part]);
2990 else
2991 NewSI = Builder.CreateAlignedStore(StoredVal, VecPtr, Alignment);
2992 }
2993 addMetadata(NewSI, SI);
2994 }
2995 return;
2996 }
2997
2998 // Handle loads.
2999 assert(LI && "Must have a load instruction")((void)0);
3000 setDebugLocFromInst(LI);
3001 for (unsigned Part = 0; Part < UF; ++Part) {
3002 Value *NewLI;
3003 if (CreateGatherScatter) {
3004 Value *MaskPart = isMaskRequired ? BlockInMaskParts[Part] : nullptr;
3005 Value *VectorGep = State.get(Addr, Part);
3006 NewLI = Builder.CreateMaskedGather(DataTy, VectorGep, Alignment, MaskPart,
3007 nullptr, "wide.masked.gather");
3008 addMetadata(NewLI, LI);
3009 } else {
3010 auto *VecPtr = CreateVecPtr(Part, State.get(Addr, VPIteration(0, 0)));
3011 if (isMaskRequired)
3012 NewLI = Builder.CreateMaskedLoad(
3013 DataTy, VecPtr, Alignment, BlockInMaskParts[Part],
3014 PoisonValue::get(DataTy), "wide.masked.load");
3015 else
3016 NewLI =
3017 Builder.CreateAlignedLoad(DataTy, VecPtr, Alignment, "wide.load");
3018
3019 // Add metadata to the load, but setVectorValue to the reverse shuffle.
3020 addMetadata(NewLI, LI);
3021 if (Reverse)
3022 NewLI = reverseVector(NewLI);
3023 }
3024
3025 State.set(Def, NewLI, Part);
3026 }
3027}
3028
3029void InnerLoopVectorizer::scalarizeInstruction(Instruction *Instr, VPValue *Def,
3030 VPUser &User,
3031 const VPIteration &Instance,
3032 bool IfPredicateInstr,
3033 VPTransformState &State) {
3034 assert(!Instr->getType()->isAggregateType() && "Can't handle vectors")((void)0);
3035
3036 // llvm.experimental.noalias.scope.decl intrinsics must only be duplicated for
3037 // the first lane and part.
3038 if (isa<NoAliasScopeDeclInst>(Instr))
3039 if (!Instance.isFirstIteration())
3040 return;
3041
3042 setDebugLocFromInst(Instr);
3043
3044 // Does this instruction return a value ?
3045 bool IsVoidRetTy = Instr->getType()->isVoidTy();
3046
3047 Instruction *Cloned = Instr->clone();
3048 if (!IsVoidRetTy)
3049 Cloned->setName(Instr->getName() + ".cloned");
3050
3051 State.Builder.SetInsertPoint(Builder.GetInsertBlock(),
3052 Builder.GetInsertPoint());
3053 // Replace the operands of the cloned instructions with their scalar
3054 // equivalents in the new loop.
3055 for (unsigned op = 0, e = User.getNumOperands(); op != e; ++op) {
3056 auto *Operand = dyn_cast<Instruction>(Instr->getOperand(op));
3057 auto InputInstance = Instance;
3058 if (!Operand || !OrigLoop->contains(Operand) ||
3059 (Cost->isUniformAfterVectorization(Operand, State.VF)))
3060 InputInstance.Lane = VPLane::getFirstLane();
3061 auto *NewOp = State.get(User.getOperand(op), InputInstance);
3062 Cloned->setOperand(op, NewOp);
3063 }
3064 addNewMetadata(Cloned, Instr);
3065
3066 // Place the cloned scalar in the new loop.
3067 Builder.Insert(Cloned);
3068
3069 State.set(Def, Cloned, Instance);
3070
3071 // If we just cloned a new assumption, add it the assumption cache.
3072 if (auto *II = dyn_cast<AssumeInst>(Cloned))
3073 AC->registerAssumption(II);
3074
3075 // End if-block.
3076 if (IfPredicateInstr)
3077 PredicatedInstructions.push_back(Cloned);
3078}
3079
3080PHINode *InnerLoopVectorizer::createInductionVariable(Loop *L, Value *Start,
3081 Value *End, Value *Step,
3082 Instruction *DL) {
3083 BasicBlock *Header = L->getHeader();
3084 BasicBlock *Latch = L->getLoopLatch();
3085 // As we're just creating this loop, it's possible no latch exists
3086 // yet. If so, use the header as this will be a single block loop.
3087 if (!Latch)
3088 Latch = Header;
3089
3090 IRBuilder<> B(&*Header->getFirstInsertionPt());
3091 Instruction *OldInst = getDebugLocFromInstOrOperands(OldInduction);
3092 setDebugLocFromInst(OldInst, &B);
3093 auto *Induction = B.CreatePHI(Start->getType(), 2, "index");
3094
3095 B.SetInsertPoint(Latch->getTerminator());
3096 setDebugLocFromInst(OldInst, &B);
3097
3098 // Create i+1 and fill the PHINode.
3099 //
3100 // If the tail is not folded, we know that End - Start >= Step (either
3101 // statically or through the minimum iteration checks). We also know that both
3102 // Start % Step == 0 and End % Step == 0. We exit the vector loop if %IV +
3103 // %Step == %End. Hence we must exit the loop before %IV + %Step unsigned
3104 // overflows and we can mark the induction increment as NUW.
3105 Value *Next = B.CreateAdd(Induction, Step, "index.next",
3106 /*NUW=*/!Cost->foldTailByMasking(), /*NSW=*/false);
3107 Induction->addIncoming(Start, L->getLoopPreheader());
3108 Induction->addIncoming(Next, Latch);
3109 // Create the compare.
3110 Value *ICmp = B.CreateICmpEQ(Next, End);
3111 B.CreateCondBr(ICmp, L->getUniqueExitBlock(), Header);
3112
3113 // Now we have two terminators. Remove the old one from the block.
3114 Latch->getTerminator()->eraseFromParent();
3115
3116 return Induction;
3117}
3118
3119Value *InnerLoopVectorizer::getOrCreateTripCount(Loop *L) {
3120 if (TripCount)
18
Assuming field 'TripCount' is null
19
Taking false branch
3121 return TripCount;
3122
3123 assert(L && "Create Trip Count for null loop.")((void)0);
3124 IRBuilder<> Builder(L->getLoopPreheader()->getTerminator());
20
Called C++ object pointer is null
3125 // Find the loop boundaries.
3126 ScalarEvolution *SE = PSE.getSE();
3127 const SCEV *BackedgeTakenCount = PSE.getBackedgeTakenCount();
3128 assert(!isa<SCEVCouldNotCompute>(BackedgeTakenCount) &&((void)0)
3129 "Invalid loop count")((void)0);
3130
3131 Type *IdxTy = Legal->getWidestInductionType();
3132 assert(IdxTy && "No type for induction")((void)0);
3133
3134 // The exit count might have the type of i64 while the phi is i32. This can
3135 // happen if we have an induction variable that is sign extended before the
3136 // compare. The only way that we get a backedge taken count is that the
3137 // induction variable was signed and as such will not overflow. In such a case
3138 // truncation is legal.
3139 if (SE->getTypeSizeInBits(BackedgeTakenCount->getType()) >
3140 IdxTy->getPrimitiveSizeInBits())
3141 BackedgeTakenCount = SE->getTruncateOrNoop(BackedgeTakenCount, IdxTy);
3142 BackedgeTakenCount = SE->getNoopOrZeroExtend(BackedgeTakenCount, IdxTy);
3143
3144 // Get the total trip count from the count by adding 1.
3145 const SCEV *ExitCount = SE->getAddExpr(
3146 BackedgeTakenCount, SE->getOne(BackedgeTakenCount->getType()));
3147
3148 const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
3149
3150 // Expand the trip count and place the new instructions in the preheader.
3151 // Notice that the pre-header does not change, only the loop body.
3152 SCEVExpander Exp(*SE, DL, "induction");
3153
3154 // Count holds the overall loop count (N).
3155 TripCount = Exp.expandCodeFor(ExitCount, ExitCount->getType(),
3156 L->getLoopPreheader()->getTerminator());
3157
3158 if (TripCount->getType()->isPointerTy())
3159 TripCount =
3160 CastInst::CreatePointerCast(TripCount, IdxTy, "exitcount.ptrcnt.to.int",
3161 L->getLoopPreheader()->getTerminator());
3162
3163 return TripCount;
3164}
3165
3166Value *InnerLoopVectorizer::getOrCreateVectorTripCount(Loop *L) {
3167 if (VectorTripCount)
3168 return VectorTripCount;
3169
3170 Value *TC = getOrCreateTripCount(L);
3171 IRBuilder<> Builder(L->getLoopPreheader()->getTerminator());
3172
3173 Type *Ty = TC->getType();
3174 // This is where we can make the step a runtime constant.
3175 Value *Step = createStepForVF(Builder, ConstantInt::get(Ty, UF), VF);
3176
3177 // If the tail is to be folded by masking, round the number of iterations N
3178 // up to a multiple of Step instead of rounding down. This is done by first
3179 // adding Step-1 and then rounding down. Note that it's ok if this addition
3180 // overflows: the vector induction variable will eventually wrap to zero given
3181 // that it starts at zero and its Step is a power of two; the loop will then
3182 // exit, with the last early-exit vector comparison also producing all-true.
3183 if (Cost->foldTailByMasking()) {
3184 assert(isPowerOf2_32(VF.getKnownMinValue() * UF) &&((void)0)
3185 "VF*UF must be a power of 2 when folding tail by masking")((void)0);
3186 assert(!VF.isScalable() &&((void)0)
3187 "Tail folding not yet supported for scalable vectors")((void)0);
3188 TC = Builder.CreateAdd(
3189 TC, ConstantInt::get(Ty, VF.getKnownMinValue() * UF - 1), "n.rnd.up");
3190 }
3191
3192 // Now we need to generate the expression for the part of the loop that the
3193 // vectorized body will execute. This is equal to N - (N % Step) if scalar
3194 // iterations are not required for correctness, or N - Step, otherwise. Step
3195 // is equal to the vectorization factor (number of SIMD elements) times the
3196 // unroll factor (number of SIMD instructions).
3197 Value *R = Builder.CreateURem(TC, Step, "n.mod.vf");
3198
3199 // There are cases where we *must* run at least one iteration in the remainder
3200 // loop. See the cost model for when this can happen. If the step evenly
3201 // divides the trip count, we set the remainder to be equal to the step. If
3202 // the step does not evenly divide the trip count, no adjustment is necessary
3203 // since there will already be scalar iterations. Note that the minimum
3204 // iterations check ensures that N >= Step.
3205 if (Cost->requiresScalarEpilogue(VF)) {
3206 auto *IsZero = Builder.CreateICmpEQ(R, ConstantInt::get(R->getType(), 0));
3207 R = Builder.CreateSelect(IsZero, Step, R);
3208 }
3209
3210 VectorTripCount = Builder.CreateSub(TC, R, "n.vec");
3211
3212 return VectorTripCount;
3213}
3214
3215Value *InnerLoopVectorizer::createBitOrPointerCast(Value *V, VectorType *DstVTy,
3216 const DataLayout &DL) {
3217 // Verify that V is a vector type with same number of elements as DstVTy.
3218 auto *DstFVTy = cast<FixedVectorType>(DstVTy);
3219 unsigned VF = DstFVTy->getNumElements();
3220 auto *SrcVecTy = cast<FixedVectorType>(V->getType());
3221 assert((VF == SrcVecTy->getNumElements()) && "Vector dimensions do not match")((void)0);
3222 Type *SrcElemTy = SrcVecTy->getElementType();
3223 Type *DstElemTy = DstFVTy->getElementType();
3224 assert((DL.getTypeSizeInBits(SrcElemTy) == DL.getTypeSizeInBits(DstElemTy)) &&((void)0)
3225 "Vector elements must have same size")((void)0);
3226
3227 // Do a direct cast if element types are castable.
3228 if (CastInst::isBitOrNoopPointerCastable(SrcElemTy, DstElemTy, DL)) {
3229 return Builder.CreateBitOrPointerCast(V, DstFVTy);
3230 }
3231 // V cannot be directly casted to desired vector type.
3232 // May happen when V is a floating point vector but DstVTy is a vector of
3233 // pointers or vice-versa. Handle this using a two-step bitcast using an
3234 // intermediate Integer type for the bitcast i.e. Ptr <-> Int <-> Float.
3235 assert((DstElemTy->isPointerTy() != SrcElemTy->isPointerTy()) &&((void)0)
3236 "Only one type should be a pointer type")((void)0);
3237 assert((DstElemTy->isFloatingPointTy() != SrcElemTy->isFloatingPointTy()) &&((void)0)
3238 "Only one type should be a floating point type")((void)0);
3239 Type *IntTy =
3240 IntegerType::getIntNTy(V->getContext(), DL.getTypeSizeInBits(SrcElemTy));
3241 auto *VecIntTy = FixedVectorType::get(IntTy, VF);
3242 Value *CastVal = Builder.CreateBitOrPointerCast(V, VecIntTy);
3243 return Builder.CreateBitOrPointerCast(CastVal, DstFVTy);
3244}
3245
3246void InnerLoopVectorizer::emitMinimumIterationCountCheck(Loop *L,
3247 BasicBlock *Bypass) {
3248 Value *Count = getOrCreateTripCount(L);
3249 // Reuse existing vector loop preheader for TC checks.
3250 // Note that new preheader block is generated for vector loop.
3251 BasicBlock *const TCCheckBlock = LoopVectorPreHeader;
3252 IRBuilder<> Builder(TCCheckBlock->getTerminator());
3253
3254 // Generate code to check if the loop's trip count is less than VF * UF, or
3255 // equal to it in case a scalar epilogue is required; this implies that the
3256 // vector trip count is zero. This check also covers the case where adding one
3257 // to the backedge-taken count overflowed leading to an incorrect trip count
3258 // of zero. In this case we will also jump to the scalar loop.
3259 auto P = Cost->requiresScalarEpilogue(VF) ? ICmpInst::ICMP_ULE
3260 : ICmpInst::ICMP_ULT;
3261
3262 // If tail is to be folded, vector loop takes care of all iterations.
3263 Value *CheckMinIters = Builder.getFalse();
3264 if (!Cost->foldTailByMasking()) {
3265 Value *Step =
3266 createStepForVF(Builder, ConstantInt::get(Count->getType(), UF), VF);
3267 CheckMinIters = Builder.CreateICmp(P, Count, Step, "min.iters.check");
3268 }
3269 // Create new preheader for vector loop.
3270 LoopVectorPreHeader =
3271 SplitBlock(TCCheckBlock, TCCheckBlock->getTerminator(), DT, LI, nullptr,
3272 "vector.ph");
3273
3274 assert(DT->properlyDominates(DT->getNode(TCCheckBlock),((void)0)
3275 DT->getNode(Bypass)->getIDom()) &&((void)0)
3276 "TC check is expected to dominate Bypass")((void)0);
3277
3278 // Update dominator for Bypass & LoopExit (if needed).
3279 DT->changeImmediateDominator(Bypass, TCCheckBlock);
3280 if (!Cost->requiresScalarEpilogue(VF))
3281 // If there is an epilogue which must run, there's no edge from the
3282 // middle block to exit blocks and thus no need to update the immediate
3283 // dominator of the exit blocks.
3284 DT->changeImmediateDominator(LoopExitBlock, TCCheckBlock);
3285
3286 ReplaceInstWithInst(
3287 TCCheckBlock->getTerminator(),
3288 BranchInst::Create(Bypass, LoopVectorPreHeader, CheckMinIters));
3289 LoopBypassBlocks.push_back(TCCheckBlock);
3290}
3291
3292BasicBlock *InnerLoopVectorizer::emitSCEVChecks(Loop *L, BasicBlock *Bypass) {
3293
3294 BasicBlock *const SCEVCheckBlock =
3295 RTChecks.emitSCEVChecks(L, Bypass, LoopVectorPreHeader, LoopExitBlock);
3296 if (!SCEVCheckBlock)
3297 return nullptr;
3298
3299 assert(!(SCEVCheckBlock->getParent()->hasOptSize() ||((void)0)
3300 (OptForSizeBasedOnProfile &&((void)0)
3301 Cost->Hints->getForce() != LoopVectorizeHints::FK_Enabled)) &&((void)0)
3302 "Cannot SCEV check stride or overflow when optimizing for size")((void)0);
3303
3304
3305 // Update dominator only if this is first RT check.
3306 if (LoopBypassBlocks.empty()) {
3307 DT->changeImmediateDominator(Bypass, SCEVCheckBlock);
3308 if (!Cost->requiresScalarEpilogue(VF))
3309 // If there is an epilogue which must run, there's no edge from the
3310 // middle block to exit blocks and thus no need to update the immediate
3311 // dominator of the exit blocks.
3312 DT->changeImmediateDominator(LoopExitBlock, SCEVCheckBlock);
3313 }
3314
3315 LoopBypassBlocks.push_back(SCEVCheckBlock);
3316 AddedSafetyChecks = true;
3317 return SCEVCheckBlock;
3318}
3319
3320BasicBlock *InnerLoopVectorizer::emitMemRuntimeChecks(Loop *L,
3321 BasicBlock *Bypass) {
3322 // VPlan-native path does not do any analysis for runtime checks currently.
3323 if (EnableVPlanNativePath)
3324 return nullptr;
3325
3326 BasicBlock *const MemCheckBlock =
3327 RTChecks.emitMemRuntimeChecks(L, Bypass, LoopVectorPreHeader);
3328
3329 // Check if we generated code that checks in runtime if arrays overlap. We put
3330 // the checks into a separate block to make the more common case of few
3331 // elements faster.
3332 if (!MemCheckBlock)
3333 return nullptr;
3334
3335 if (MemCheckBlock->getParent()->hasOptSize() || OptForSizeBasedOnProfile) {
3336 assert(Cost->Hints->getForce() == LoopVectorizeHints::FK_Enabled &&((void)0)
3337 "Cannot emit memory checks when optimizing for size, unless forced "((void)0)
3338 "to vectorize.")((void)0);
3339 ORE->emit([&]() {
3340 return OptimizationRemarkAnalysis(DEBUG_TYPE"loop-vectorize", "VectorizationCodeSize",
3341 L->getStartLoc(), L->getHeader())
3342 << "Code-size may be reduced by not forcing "
3343 "vectorization, or by source-code modifications "
3344 "eliminating the need for runtime checks "
3345 "(e.g., adding 'restrict').";
3346 });
3347 }
3348
3349 LoopBypassBlocks.push_back(MemCheckBlock);
3350
3351 AddedSafetyChecks = true;
3352
3353 // We currently don't use LoopVersioning for the actual loop cloning but we
3354 // still use it to add the noalias metadata.
3355 LVer = std::make_unique<LoopVersioning>(
3356 *Legal->getLAI(),
3357 Legal->getLAI()->getRuntimePointerChecking()->getChecks(), OrigLoop, LI,
3358 DT, PSE.getSE());
3359 LVer->prepareNoAliasMetadata();
3360 return MemCheckBlock;
3361}
3362
3363Value *InnerLoopVectorizer::emitTransformedIndex(
3364 IRBuilder<> &B, Value *Index, ScalarEvolution *SE, const DataLayout &DL,
3365 const InductionDescriptor &ID) const {
3366
3367 SCEVExpander Exp(*SE, DL, "induction");
3368 auto Step = ID.getStep();
3369 auto StartValue = ID.getStartValue();
3370 assert(Index->getType()->getScalarType() == Step->getType() &&((void)0)
3371 "Index scalar type does not match StepValue type")((void)0);
3372
3373 // Note: the IR at this point is broken. We cannot use SE to create any new
3374 // SCEV and then expand it, hoping that SCEV's simplification will give us
3375 // a more optimal code. Unfortunately, attempt of doing so on invalid IR may
3376 // lead to various SCEV crashes. So all we can do is to use builder and rely
3377 // on InstCombine for future simplifications. Here we handle some trivial
3378 // cases only.
3379 auto CreateAdd = [&B](Value *X, Value *Y) {
3380 assert(X->getType() == Y->getType() && "Types don't match!")((void)0);
3381 if (auto *CX = dyn_cast<ConstantInt>(X))
3382 if (CX->isZero())
3383 return Y;
3384 if (auto *CY = dyn_cast<ConstantInt>(Y))
3385 if (CY->isZero())
3386 return X;
3387 return B.CreateAdd(X, Y);
3388 };
3389
3390 // We allow X to be a vector type, in which case Y will potentially be
3391 // splatted into a vector with the same element count.
3392 auto CreateMul = [&B](Value *X, Value *Y) {
3393 assert(X->getType()->getScalarType() == Y->getType() &&((void)0)
3394 "Types don't match!")((void)0);
3395 if (auto *CX = dyn_cast<ConstantInt>(X))
3396 if (CX->isOne())
3397 return Y;
3398 if (auto *CY = dyn_cast<ConstantInt>(Y))
3399 if (CY->isOne())
3400 return X;
3401 VectorType *XVTy = dyn_cast<VectorType>(X->getType());
3402 if (XVTy && !isa<VectorType>(Y->getType()))
3403 Y = B.CreateVectorSplat(XVTy->getElementCount(), Y);
3404 return B.CreateMul(X, Y);
3405 };
3406
3407 // Get a suitable insert point for SCEV expansion. For blocks in the vector
3408 // loop, choose the end of the vector loop header (=LoopVectorBody), because
3409 // the DomTree is not kept up-to-date for additional blocks generated in the
3410 // vector loop. By using the header as insertion point, we guarantee that the
3411 // expanded instructions dominate all their uses.
3412 auto GetInsertPoint = [this, &B]() {
3413 BasicBlock *InsertBB = B.GetInsertPoint()->getParent();
3414 if (InsertBB != LoopVectorBody &&
3415 LI->getLoopFor(LoopVectorBody) == LI->getLoopFor(InsertBB))
3416 return LoopVectorBody->getTerminator();
3417 return &*B.GetInsertPoint();
3418 };
3419
3420 switch (ID.getKind()) {
3421 case InductionDescriptor::IK_IntInduction: {
3422 assert(!isa<VectorType>(Index->getType()) &&((void)0)
3423 "Vector indices not supported for integer inductions yet")((void)0);
3424 assert(Index->getType() == StartValue->getType() &&((void)0)
3425 "Index type does not match StartValue type")((void)0);
3426 if (ID.getConstIntStepValue() && ID.getConstIntStepValue()->isMinusOne())
3427 return B.CreateSub(StartValue, Index);
3428 auto *Offset = CreateMul(
3429 Index, Exp.expandCodeFor(Step, Index->getType(), GetInsertPoint()));
3430 return CreateAdd(StartValue, Offset);
3431 }
3432 case InductionDescriptor::IK_PtrInduction: {
3433 assert(isa<SCEVConstant>(Step) &&((void)0)
3434 "Expected constant step for pointer induction")((void)0);
3435 return B.CreateGEP(
3436 StartValue->getType()->getPointerElementType(), StartValue,
3437 CreateMul(Index,
3438 Exp.expandCodeFor(Step, Index->getType()->getScalarType(),
3439 GetInsertPoint())));
3440 }
3441 case InductionDescriptor::IK_FpInduction: {
3442 assert(!isa<VectorType>(Index->getType()) &&((void)0)
3443 "Vector indices not supported for FP inductions yet")((void)0);
3444 assert(Step->getType()->isFloatingPointTy() && "Expected FP Step value")((void)0);
3445 auto InductionBinOp = ID.getInductionBinOp();
3446 assert(InductionBinOp &&((void)0)
3447 (InductionBinOp->getOpcode() == Instruction::FAdd ||((void)0)
3448 InductionBinOp->getOpcode() == Instruction::FSub) &&((void)0)
3449 "Original bin op should be defined for FP induction")((void)0);
3450
3451 Value *StepValue = cast<SCEVUnknown>(Step)->getValue();
3452 Value *MulExp = B.CreateFMul(StepValue, Index);
3453 return B.CreateBinOp(InductionBinOp->getOpcode(), StartValue, MulExp,
3454 "induction");
3455 }
3456 case InductionDescriptor::IK_NoInduction:
3457 return nullptr;
3458 }
3459 llvm_unreachable("invalid enum")__builtin_unreachable();
3460}
3461
3462Loop *InnerLoopVectorizer::createVectorLoopSkeleton(StringRef Prefix) {
3463 LoopScalarBody = OrigLoop->getHeader();
3464 LoopVectorPreHeader = OrigLoop->getLoopPreheader();
3465 assert(LoopVectorPreHeader && "Invalid loop structure")((void)0);
3466 LoopExitBlock = OrigLoop->getUniqueExitBlock(); // may be nullptr
3467 assert((LoopExitBlock || Cost->requiresScalarEpilogue(VF)) &&((void)0)
3468 "multiple exit loop without required epilogue?")((void)0);
3469
3470 LoopMiddleBlock =
3471 SplitBlock(LoopVectorPreHeader, LoopVectorPreHeader->getTerminator(), DT,
3472 LI, nullptr, Twine(Prefix) + "middle.block");
3473 LoopScalarPreHeader =
3474 SplitBlock(LoopMiddleBlock, LoopMiddleBlock->getTerminator(), DT, LI,
3475 nullptr, Twine(Prefix) + "scalar.ph");
3476
3477 auto *ScalarLatchTerm = OrigLoop->getLoopLatch()->getTerminator();
3478
3479 // Set up the middle block terminator. Two cases:
3480 // 1) If we know that we must execute the scalar epilogue, emit an
3481 // unconditional branch.
3482 // 2) Otherwise, we must have a single unique exit block (due to how we
3483 // implement the multiple exit case). In this case, set up a conditonal
3484 // branch from the middle block to the loop scalar preheader, and the
3485 // exit block. completeLoopSkeleton will update the condition to use an
3486 // iteration check, if required to decide whether to execute the remainder.
3487 BranchInst *BrInst = Cost->requiresScalarEpilogue(VF) ?
3488 BranchInst::Create(LoopScalarPreHeader) :
3489 BranchInst::Create(LoopExitBlock, LoopScalarPreHeader,
3490 Builder.getTrue());
3491 BrInst->setDebugLoc(ScalarLatchTerm->getDebugLoc());
3492 ReplaceInstWithInst(LoopMiddleBlock->getTerminator(), BrInst);
3493
3494 // We intentionally don't let SplitBlock to update LoopInfo since
3495 // LoopVectorBody should belong to another loop than LoopVectorPreHeader.
3496 // LoopVectorBody is explicitly added to the correct place few lines later.
3497 LoopVectorBody =
3498 SplitBlock(LoopVectorPreHeader, LoopVectorPreHeader->getTerminator(), DT,
3499 nullptr, nullptr, Twine(Prefix) + "vector.body");
3500
3501 // Update dominator for loop exit.
3502 if (!Cost->requiresScalarEpilogue(VF))
3503 // If there is an epilogue which must run, there's no edge from the
3504 // middle block to exit blocks and thus no need to update the immediate
3505 // dominator of the exit blocks.
3506 DT->changeImmediateDominator(LoopExitBlock, LoopMiddleBlock);
3507
3508 // Create and register the new vector loop.
3509 Loop *Lp = LI->AllocateLoop();
3510 Loop *ParentLoop = OrigLoop->getParentLoop();
3511
3512 // Insert the new loop into the loop nest and register the new basic blocks
3513 // before calling any utilities such as SCEV that require valid LoopInfo.
3514 if (ParentLoop) {
3515 ParentLoop->addChildLoop(Lp);
3516 } else {
3517 LI->addTopLevelLoop(Lp);
3518 }
3519 Lp->addBasicBlockToLoop(LoopVectorBody, *LI);
3520 return Lp;
3521}
3522
3523void InnerLoopVectorizer::createInductionResumeValues(
3524 Loop *L, Value *VectorTripCount,
3525 std::pair<BasicBlock *, Value *> AdditionalBypass) {
3526 assert(VectorTripCount && L && "Expected valid arguments")((void)0);
3527 assert(((AdditionalBypass.first && AdditionalBypass.second) ||((void)0)
3528 (!AdditionalBypass.first && !AdditionalBypass.second)) &&((void)0)
3529 "Inconsistent information about additional bypass.")((void)0);
3530 // We are going to resume the execution of the scalar loop.
3531 // Go over all of the induction variables that we found and fix the
3532 // PHIs that are left in the scalar version of the loop.
3533 // The starting values of PHI nodes depend on the counter of the last
3534 // iteration in the vectorized loop.
3535 // If we come from a bypass edge then we need to start from the original
3536 // start value.
3537 for (auto &InductionEntry : Legal->getInductionVars()) {
3538 PHINode *OrigPhi = InductionEntry.first;
3539 InductionDescriptor II = InductionEntry.second;
3540
3541 // Create phi nodes to merge from the backedge-taken check block.
3542 PHINode *BCResumeVal =
3543 PHINode::Create(OrigPhi->getType(), 3, "bc.resume.val",
3544 LoopScalarPreHeader->getTerminator());
3545 // Copy original phi DL over to the new one.
3546 BCResumeVal->setDebugLoc(OrigPhi->getDebugLoc());
3547 Value *&EndValue = IVEndValues[OrigPhi];
3548 Value *EndValueFromAdditionalBypass = AdditionalBypass.second;
3549 if (OrigPhi == OldInduction) {
3550 // We know what the end value is.
3551 EndValue = VectorTripCount;
3552 } else {
3553 IRBuilder<> B(L->getLoopPreheader()->getTerminator());
3554
3555 // Fast-math-flags propagate from the original induction instruction.
3556 if (II.getInductionBinOp() && isa<FPMathOperator>(II.getInductionBinOp()))
3557 B.setFastMathFlags(II.getInductionBinOp()->getFastMathFlags());
3558
3559 Type *StepType = II.getStep()->getType();
3560 Instruction::CastOps CastOp =
3561 CastInst::getCastOpcode(VectorTripCount, true, StepType, true);
3562 Value *CRD = B.CreateCast(CastOp, VectorTripCount, StepType, "cast.crd");
3563 const DataLayout &DL = LoopScalarBody->getModule()->getDataLayout();
3564 EndValue = emitTransformedIndex(B, CRD, PSE.getSE(), DL, II);
3565 EndValue->setName("ind.end");
3566
3567 // Compute the end value for the additional bypass (if applicable).
3568 if (AdditionalBypass.first) {
3569 B.SetInsertPoint(&(*AdditionalBypass.first->getFirstInsertionPt()));
3570 CastOp = CastInst::getCastOpcode(AdditionalBypass.second, true,
3571 StepType, true);
3572 CRD =
3573 B.CreateCast(CastOp, AdditionalBypass.second, StepType, "cast.crd");
3574 EndValueFromAdditionalBypass =
3575 emitTransformedIndex(B, CRD, PSE.getSE(), DL, II);
3576 EndValueFromAdditionalBypass->setName("ind.end");
3577 }
3578 }
3579 // The new PHI merges the original incoming value, in case of a bypass,
3580 // or the value at the end of the vectorized loop.
3581 BCResumeVal->addIncoming(EndValue, LoopMiddleBlock);
3582
3583 // Fix the scalar body counter (PHI node).
3584 // The old induction's phi node in the scalar body needs the truncated
3585 // value.
3586 for (BasicBlock *BB : LoopBypassBlocks)
3587 BCResumeVal->addIncoming(II.getStartValue(), BB);
3588
3589 if (AdditionalBypass.first)
3590 BCResumeVal->setIncomingValueForBlock(AdditionalBypass.first,
3591 EndValueFromAdditionalBypass);
3592
3593 OrigPhi->setIncomingValueForBlock(LoopScalarPreHeader, BCResumeVal);
3594 }
3595}
3596
3597BasicBlock *InnerLoopVectorizer::completeLoopSkeleton(Loop *L,
3598 MDNode *OrigLoopID) {
3599 assert(L && "Expected valid loop.")((void)0);
3600
3601 // The trip counts should be cached by now.
3602 Value *Count = getOrCreateTripCount(L);
3603 Value *VectorTripCount = getOrCreateVectorTripCount(L);
3604
3605 auto *ScalarLatchTerm = OrigLoop->getLoopLatch()->getTerminator();
3606
3607 // Add a check in the middle block to see if we have completed
3608 // all of the iterations in the first vector loop. Three cases:
3609 // 1) If we require a scalar epilogue, there is no conditional branch as
3610 // we unconditionally branch to the scalar preheader. Do nothing.
3611 // 2) If (N - N%VF) == N, then we *don't* need to run the remainder.
3612 // Thus if tail is to be folded, we know we don't need to run the
3613 // remainder and we can use the previous value for the condition (true).
3614 // 3) Otherwise, construct a runtime check.
3615 if (!Cost->requiresScalarEpilogue(VF) && !Cost->foldTailByMasking()) {
3616 Instruction *CmpN = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ,
3617 Count, VectorTripCount, "cmp.n",
3618 LoopMiddleBlock->getTerminator());
3619
3620 // Here we use the same DebugLoc as the scalar loop latch terminator instead
3621 // of the corresponding compare because they may have ended up with
3622 // different line numbers and we want to avoid awkward line stepping while
3623 // debugging. Eg. if the compare has got a line number inside the loop.
3624 CmpN->setDebugLoc(ScalarLatchTerm->getDebugLoc());
3625 cast<BranchInst>(LoopMiddleBlock->getTerminator())->setCondition(CmpN);
3626 }
3627
3628 // Get ready to start creating new instructions into the vectorized body.
3629 assert(LoopVectorPreHeader == L->getLoopPreheader() &&((void)0)
3630 "Inconsistent vector loop preheader")((void)0);
3631 Builder.SetInsertPoint(&*LoopVectorBody->getFirstInsertionPt());
3632
3633 Optional<MDNode *> VectorizedLoopID =
3634 makeFollowupLoopID(OrigLoopID, {LLVMLoopVectorizeFollowupAll,
3635 LLVMLoopVectorizeFollowupVectorized});
3636 if (VectorizedLoopID.hasValue()) {
3637 L->setLoopID(VectorizedLoopID.getValue());
3638
3639 // Do not setAlreadyVectorized if loop attributes have been defined
3640 // explicitly.
3641 return LoopVectorPreHeader;
3642 }
3643
3644 // Keep all loop hints from the original loop on the vector loop (we'll
3645 // replace the vectorizer-specific hints below).
3646 if (MDNode *LID = OrigLoop->getLoopID())
3647 L->setLoopID(LID);
3648
3649 LoopVectorizeHints Hints(L, true, *ORE);
3650 Hints.setAlreadyVectorized();
3651
3652#ifdef EXPENSIVE_CHECKS
3653 assert(DT->verify(DominatorTree::VerificationLevel::Fast))((void)0);
3654 LI->verify(*DT);
3655#endif
3656
3657 return LoopVectorPreHeader;
3658}
3659
3660BasicBlock *InnerLoopVectorizer::createVectorizedLoopSkeleton() {
3661 /*
3662 In this function we generate a new loop. The new loop will contain
3663 the vectorized instructions while the old loop will continue to run the
3664 scalar remainder.
3665
3666 [ ] <-- loop iteration number check.
3667 / |
3668 / v
3669 | [ ] <-- vector loop bypass (may consist of multiple blocks).
3670 | / |
3671 | / v
3672 || [ ] <-- vector pre header.
3673 |/ |
3674 | v
3675 | [ ] \
3676 | [ ]_| <-- vector loop.
3677 | |
3678 | v
3679 \ -[ ] <--- middle-block.
3680 \/ |
3681 /\ v
3682 | ->[ ] <--- new preheader.
3683 | |
3684 (opt) v <-- edge from middle to exit iff epilogue is not required.
3685 | [ ] \
3686 | [ ]_| <-- old scalar loop to handle remainder (scalar epilogue).
3687 \ |
3688 \ v
3689 >[ ] <-- exit block(s).
3690 ...
3691 */
3692
3693 // Get the metadata of the original loop before it gets modified.
3694 MDNode *OrigLoopID = OrigLoop->getLoopID();
3695
3696 // Workaround! Compute the trip count of the original loop and cache it
3697 // before we start modifying the CFG. This code has a systemic problem
3698 // wherein it tries to run analysis over partially constructed IR; this is
3699 // wrong, and not simply for SCEV. The trip count of the original loop
3700 // simply happens to be prone to hitting this in practice. In theory, we
3701 // can hit the same issue for any SCEV, or ValueTracking query done during
3702 // mutation. See PR49900.
3703 getOrCreateTripCount(OrigLoop);
3704
3705 // Create an empty vector loop, and prepare basic blocks for the runtime
3706 // checks.
3707 Loop *Lp = createVectorLoopSkeleton("");
3708
3709 // Now, compare the new count to zero. If it is zero skip the vector loop and
3710 // jump to the scalar loop. This check also covers the case where the
3711 // backedge-taken count is uint##_max: adding one to it will overflow leading
3712 // to an incorrect trip count of zero. In this (rare) case we will also jump
3713 // to the scalar loop.
3714 emitMinimumIterationCountCheck(Lp, LoopScalarPreHeader);
3715
3716 // Generate the code to check any assumptions that we've made for SCEV
3717 // expressions.
3718 emitSCEVChecks(Lp, LoopScalarPreHeader);
3719
3720 // Generate the code that checks in runtime if arrays overlap. We put the
3721 // checks into a separate block to make the more common case of few elements
3722 // faster.
3723 emitMemRuntimeChecks(Lp, LoopScalarPreHeader);
3724
3725 // Some loops have a single integer induction variable, while other loops
3726 // don't. One example is c++ iterators that often have multiple pointer
3727 // induction variables. In the code below we also support a case where we
3728 // don't have a single induction variable.
3729 //
3730 // We try to obtain an induction variable from the original loop as hard
3731 // as possible. However if we don't find one that:
3732 // - is an integer
3733 // - counts from zero, stepping by one
3734 // - is the size of the widest induction variable type
3735 // then we create a new one.
3736 OldInduction = Legal->getPrimaryInduction();
3737 Type *IdxTy = Legal->getWidestInductionType();
3738 Value *StartIdx = ConstantInt::get(IdxTy, 0);
3739 // The loop step is equal to the vectorization factor (num of SIMD elements)
3740 // times the unroll factor (num of SIMD instructions).
3741 Builder.SetInsertPoint(&*Lp->getHeader()->getFirstInsertionPt());
3742 Value *Step = createStepForVF(Builder, ConstantInt::get(IdxTy, UF), VF);
3743 Value *CountRoundDown = getOrCreateVectorTripCount(Lp);
3744 Induction =
3745 createInductionVariable(Lp, StartIdx, CountRoundDown, Step,
3746 getDebugLocFromInstOrOperands(OldInduction));
3747
3748 // Emit phis for the new starting index of the scalar loop.
3749 createInductionResumeValues(Lp, CountRoundDown);
3750
3751 return completeLoopSkeleton(Lp, OrigLoopID);
3752}
3753
3754// Fix up external users of the induction variable. At this point, we are
3755// in LCSSA form, with all external PHIs that use the IV having one input value,
3756// coming from the remainder loop. We need those PHIs to also have a correct
3757// value for the IV when arriving directly from the middle block.
3758void InnerLoopVectorizer::fixupIVUsers(PHINode *OrigPhi,
3759 const InductionDescriptor &II,
3760 Value *CountRoundDown, Value *EndValue,
3761 BasicBlock *MiddleBlock) {
3762 // There are two kinds of external IV usages - those that use the value
3763 // computed in the last iteration (the PHI) and those that use the penultimate
3764 // value (the value that feeds into the phi from the loop latch).
3765 // We allow both, but they, obviously, have different values.
3766
3767 assert(OrigLoop->getUniqueExitBlock() && "Expected a single exit block")((void)0);
3768
3769 DenseMap<Value *, Value *> MissingVals;
3770
3771 // An external user of the last iteration's value should see the value that
3772 // the remainder loop uses to initialize its own IV.
3773 Value *PostInc = OrigPhi->getIncomingValueForBlock(OrigLoop->getLoopLatch());
3774 for (User *U : PostInc->users()) {
3775 Instruction *UI = cast<Instruction>(U);
3776 if (!OrigLoop->contains(UI)) {
3777 assert(isa<PHINode>(UI) && "Expected LCSSA form")((void)0);
3778 MissingVals[UI] = EndValue;
3779 }
3780 }
3781
3782 // An external user of the penultimate value need to see EndValue - Step.
3783 // The simplest way to get this is to recompute it from the constituent SCEVs,
3784 // that is Start + (Step * (CRD - 1)).
3785 for (User *U : OrigPhi->users()) {
3786 auto *UI = cast<Instruction>(U);
3787 if (!OrigLoop->contains(UI)) {
3788 const DataLayout &DL =
3789 OrigLoop->getHeader()->getModule()->getDataLayout();
3790 assert(isa<PHINode>(UI) && "Expected LCSSA form")((void)0);
3791
3792 IRBuilder<> B(MiddleBlock->getTerminator());
3793
3794 // Fast-math-flags propagate from the original induction instruction.
3795 if (II.getInductionBinOp() && isa<FPMathOperator>(II.getInductionBinOp()))
3796 B.setFastMathFlags(II.getInductionBinOp()->getFastMathFlags());
3797
3798 Value *CountMinusOne = B.CreateSub(
3799 CountRoundDown, ConstantInt::get(CountRoundDown->getType(), 1));
3800 Value *CMO =
3801 !II.getStep()->getType()->isIntegerTy()
3802 ? B.CreateCast(Instruction::SIToFP, CountMinusOne,
3803 II.getStep()->getType())
3804 : B.CreateSExtOrTrunc(CountMinusOne, II.getStep()->getType());
3805 CMO->setName("cast.cmo");
3806 Value *Escape = emitTransformedIndex(B, CMO, PSE.getSE(), DL, II);
3807 Escape->setName("ind.escape");
3808 MissingVals[UI] = Escape;
3809 }
3810 }
3811
3812 for (auto &I : MissingVals) {
3813 PHINode *PHI = cast<PHINode>(I.first);
3814 // One corner case we have to handle is two IVs "chasing" each-other,
3815 // that is %IV2 = phi [...], [ %IV1, %latch ]
3816 // In this case, if IV1 has an external use, we need to avoid adding both
3817 // "last value of IV1" and "penultimate value of IV2". So, verify that we
3818 // don't already have an incoming value for the middle block.
3819 if (PHI->getBasicBlockIndex(MiddleBlock) == -1)
3820 PHI->addIncoming(I.second, MiddleBlock);
3821 }
3822}
3823
3824namespace {
3825
3826struct CSEDenseMapInfo {
3827 static bool canHandle(const Instruction *I) {
3828 return isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
3829 isa<ShuffleVectorInst>(I) || isa<GetElementPtrInst>(I);
3830 }
3831
3832 static inline Instruction *getEmptyKey() {
3833 return DenseMapInfo<Instruction *>::getEmptyKey();
3834 }
3835
3836 static inline Instruction *getTombstoneKey() {
3837 return DenseMapInfo<Instruction *>::getTombstoneKey();
3838 }
3839
3840 static unsigned getHashValue(const Instruction *I) {
3841 assert(canHandle(I) && "Unknown instruction!")((void)0);
3842 return hash_combine(I->getOpcode(), hash_combine_range(I->value_op_begin(),
3843 I->value_op_end()));
3844 }
3845
3846 static bool isEqual(const Instruction *LHS, const Instruction *RHS) {
3847 if (LHS == getEmptyKey() || RHS == getEmptyKey() ||
3848 LHS == getTombstoneKey() || RHS == getTombstoneKey())
3849 return LHS == RHS;
3850 return LHS->isIdenticalTo(RHS);
3851 }
3852};
3853
3854} // end anonymous namespace
3855
3856///Perform cse of induction variable instructions.
3857static void cse(BasicBlock *BB) {
3858 // Perform simple cse.
3859 SmallDenseMap<Instruction *, Instruction *, 4, CSEDenseMapInfo> CSEMap;
3860 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
3861 Instruction *In = &*I++;
3862
3863 if (!CSEDenseMapInfo::canHandle(In))
3864 continue;
3865
3866 // Check if we can replace this instruction with any of the
3867 // visited instructions.
3868 if (Instruction *V = CSEMap.lookup(In)) {
3869 In->replaceAllUsesWith(V);
3870 In->eraseFromParent();
3871 continue;
3872 }
3873
3874 CSEMap[In] = In;
3875 }
3876}
3877
3878InstructionCost
3879LoopVectorizationCostModel::getVectorCallCost(CallInst *CI, ElementCount VF,
3880 bool &NeedToScalarize) const {
3881 Function *F = CI->getCalledFunction();
3882 Type *ScalarRetTy = CI->getType();
3883 SmallVector<Type *, 4> Tys, ScalarTys;
3884 for (auto &ArgOp : CI->arg_operands())
3885 ScalarTys.push_back(ArgOp->getType());
3886
3887 // Estimate cost of scalarized vector call. The source operands are assumed
3888 // to be vectors, so we need to extract individual elements from there,
3889 // execute VF scalar calls, and then gather the result into the vector return
3890 // value.
3891 InstructionCost ScalarCallCost =
3892 TTI.getCallInstrCost(F, ScalarRetTy, ScalarTys, TTI::TCK_RecipThroughput);
3893 if (VF.isScalar())
3894 return ScalarCallCost;
3895
3896 // Compute corresponding vector type for return value and arguments.
3897 Type *RetTy = ToVectorTy(ScalarRetTy, VF);
3898 for (Type *ScalarTy : ScalarTys)
3899 Tys.push_back(ToVectorTy(ScalarTy, VF));
3900
3901 // Compute costs of unpacking argument values for the scalar calls and
3902 // packing the return values to a vector.
3903 InstructionCost ScalarizationCost = getScalarizationOverhead(CI, VF);
3904
3905 InstructionCost Cost =
3906 ScalarCallCost * VF.getKnownMinValue() + ScalarizationCost;
3907
3908 // If we can't emit a vector call for this function, then the currently found
3909 // cost is the cost we need to return.
3910 NeedToScalarize = true;
3911 VFShape Shape = VFShape::get(*CI, VF, false /*HasGlobalPred*/);
3912 Function *VecFunc = VFDatabase(*CI).getVectorizedFunction(Shape);
3913
3914 if (!TLI || CI->isNoBuiltin() || !VecFunc)
3915 return Cost;
3916
3917 // If the corresponding vector cost is cheaper, return its cost.
3918 InstructionCost VectorCallCost =
3919 TTI.getCallInstrCost(nullptr, RetTy, Tys, TTI::TCK_RecipThroughput);
3920 if (VectorCallCost < Cost) {
3921 NeedToScalarize = false;
3922 Cost = VectorCallCost;
3923 }
3924 return Cost;
3925}
3926
3927static Type *MaybeVectorizeType(Type *Elt, ElementCount VF) {
3928 if (VF.isScalar() || (!Elt->isIntOrPtrTy() && !Elt->isFloatingPointTy()))
3929 return Elt;
3930 return VectorType::get(Elt, VF);
3931}
3932
3933InstructionCost
3934LoopVectorizationCostModel::getVectorIntrinsicCost(CallInst *CI,
3935 ElementCount VF) const {
3936 Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
3937 assert(ID && "Expected intrinsic call!")((void)0);
3938 Type *RetTy = MaybeVectorizeType(CI->getType(), VF);
3939 FastMathFlags FMF;
3940 if (auto *FPMO = dyn_cast<FPMathOperator>(CI))
3941 FMF = FPMO->getFastMathFlags();
3942
3943 SmallVector<const Value *> Arguments(CI->arg_begin(), CI->arg_end());
3944 FunctionType *FTy = CI->getCalledFunction()->getFunctionType();
3945 SmallVector<Type *> ParamTys;
3946 std::transform(FTy->param_begin(), FTy->param_end(),
3947 std::back_inserter(ParamTys),
3948 [&](Type *Ty) { return MaybeVectorizeType(Ty, VF); });
3949
3950 IntrinsicCostAttributes CostAttrs(ID, RetTy, Arguments, ParamTys, FMF,
3951 dyn_cast<IntrinsicInst>(CI));
3952 return TTI.getIntrinsicInstrCost(CostAttrs,
3953 TargetTransformInfo::TCK_RecipThroughput);
3954}
3955
3956static Type *smallestIntegerVectorType(Type *T1, Type *T2) {
3957 auto *I1 = cast<IntegerType>(cast<VectorType>(T1)->getElementType());
3958 auto *I2 = cast<IntegerType>(cast<VectorType>(T2)->getElementType());
3959 return I1->getBitWidth() < I2->getBitWidth() ? T1 : T2;
3960}
3961
3962static Type *largestIntegerVectorType(Type *T1, Type *T2) {
3963 auto *I1 = cast<IntegerType>(cast<VectorType>(T1)->getElementType());
3964 auto *I2 = cast<IntegerType>(cast<VectorType>(T2)->getElementType());
3965 return I1->getBitWidth() > I2->getBitWidth() ? T1 : T2;
3966}
3967
3968void InnerLoopVectorizer::truncateToMinimalBitwidths(VPTransformState &State) {
3969 // For every instruction `I` in MinBWs, truncate the operands, create a
3970 // truncated version of `I` and reextend its result. InstCombine runs
3971 // later and will remove any ext/trunc pairs.
3972 SmallPtrSet<Value *, 4> Erased;
3973 for (const auto &KV : Cost->getMinimalBitwidths()) {
3974 // If the value wasn't vectorized, we must maintain the original scalar
3975 // type. The absence of the value from State indicates that it
3976 // wasn't vectorized.
3977 VPValue *Def = State.Plan->getVPValue(KV.first);
3978 if (!State.hasAnyVectorValue(Def))
3979 continue;
3980 for (unsigned Part = 0; Part < UF; ++Part) {
3981 Value *I = State.get(Def, Part);
3982 if (Erased.count(I) || I->use_empty() || !isa<Instruction>(I))
3983 continue;
3984 Type *OriginalTy = I->getType();
3985 Type *ScalarTruncatedTy =
3986 IntegerType::get(OriginalTy->getContext(), KV.second);
3987 auto *TruncatedTy = VectorType::get(
3988 ScalarTruncatedTy, cast<VectorType>(OriginalTy)->getElementCount());
3989 if (TruncatedTy == OriginalTy)
3990 continue;
3991
3992 IRBuilder<> B(cast<Instruction>(I));
3993 auto ShrinkOperand = [&](Value *V) -> Value * {
3994 if (auto *ZI = dyn_cast<ZExtInst>(V))
3995 if (ZI->getSrcTy() == TruncatedTy)
3996 return ZI->getOperand(0);
3997 return B.CreateZExtOrTrunc(V, TruncatedTy);
3998 };
3999
4000 // The actual instruction modification depends on the instruction type,
4001 // unfortunately.
4002 Value *NewI = nullptr;
4003 if (auto *BO = dyn_cast<BinaryOperator>(I)) {
4004 NewI = B.CreateBinOp(BO->getOpcode(), ShrinkOperand(BO->getOperand(0)),
4005 ShrinkOperand(BO->getOperand(1)));
4006
4007 // Any wrapping introduced by shrinking this operation shouldn't be
4008 // considered undefined behavior. So, we can't unconditionally copy
4009 // arithmetic wrapping flags to NewI.
4010 cast<BinaryOperator>(NewI)->copyIRFlags(I, /*IncludeWrapFlags=*/false);
4011 } else if (auto *CI = dyn_cast<ICmpInst>(I)) {
4012 NewI =
4013 B.CreateICmp(CI->getPredicate(), ShrinkOperand(CI->getOperand(0)),
4014 ShrinkOperand(CI->getOperand(1)));
4015 } else if (auto *SI = dyn_cast<SelectInst>(I)) {
4016 NewI = B.CreateSelect(SI->getCondition(),
4017 ShrinkOperand(SI->getTrueValue()),
4018 ShrinkOperand(SI->getFalseValue()));
4019 } else if (auto *CI = dyn_cast<CastInst>(I)) {
4020 switch (CI->getOpcode()) {
4021 default:
4022 llvm_unreachable("Unhandled cast!")__builtin_unreachable();
4023 case Instruction::Trunc:
4024 NewI = ShrinkOperand(CI->getOperand(0));
4025 break;
4026 case Instruction::SExt:
4027 NewI = B.CreateSExtOrTrunc(
4028 CI->getOperand(0),
4029 smallestIntegerVectorType(OriginalTy, TruncatedTy));
4030 break;
4031 case Instruction::ZExt:
4032 NewI = B.CreateZExtOrTrunc(
4033 CI->getOperand(0),
4034 smallestIntegerVectorType(OriginalTy, TruncatedTy));
4035 break;
4036 }
4037 } else if (auto *SI = dyn_cast<ShuffleVectorInst>(I)) {
4038 auto Elements0 =
4039 cast<VectorType>(SI->getOperand(0)->getType())->getElementCount();
4040 auto *O0 = B.CreateZExtOrTrunc(
4041 SI->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements0));
4042 auto Elements1 =
4043 cast<VectorType>(SI->getOperand(1)->getType())->getElementCount();
4044 auto *O1 = B.CreateZExtOrTrunc(
4045 SI->getOperand(1), VectorType::get(ScalarTruncatedTy, Elements1));
4046
4047 NewI = B.CreateShuffleVector(O0, O1, SI->getShuffleMask());
4048 } else if (isa<LoadInst>(I) || isa<PHINode>(I)) {
4049 // Don't do anything with the operands, just extend the result.
4050 continue;
4051 } else if (auto *IE = dyn_cast<InsertElementInst>(I)) {
4052 auto Elements =
4053 cast<VectorType>(IE->getOperand(0)->getType())->getElementCount();
4054 auto *O0 = B.CreateZExtOrTrunc(
4055 IE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
4056 auto *O1 = B.CreateZExtOrTrunc(IE->getOperand(1), ScalarTruncatedTy);
4057 NewI = B.CreateInsertElement(O0, O1, IE->getOperand(2));
4058 } else if (auto *EE = dyn_cast<ExtractElementInst>(I)) {
4059 auto Elements =
4060 cast<VectorType>(EE->getOperand(0)->getType())->getElementCount();
4061 auto *O0 = B.CreateZExtOrTrunc(
4062 EE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
4063 NewI = B.CreateExtractElement(O0, EE->getOperand(2));
4064 } else {
4065 // If we don't know what to do, be conservative and don't do anything.
4066 continue;
4067 }
4068
4069 // Lastly, extend the result.
4070 NewI->takeName(cast<Instruction>(I));
4071 Value *Res = B.CreateZExtOrTrunc(NewI, OriginalTy);
4072 I->replaceAllUsesWith(Res);
4073 cast<Instruction>(I)->eraseFromParent();
4074 Erased.insert(I);
4075 State.reset(Def, Res, Part);
4076 }
4077 }
4078
4079 // We'll have created a bunch of ZExts that are now parentless. Clean up.
4080 for (const auto &KV : Cost->getMinimalBitwidths()) {
4081 // If the value wasn't vectorized, we must maintain the original scalar
4082 // type. The absence of the value from State indicates that it
4083 // wasn't vectorized.
4084 VPValue *Def = State.Plan->getVPValue(KV.first);
4085 if (!State.hasAnyVectorValue(Def))
4086 continue;
4087 for (unsigned Part = 0; Part < UF; ++Part) {
4088 Value *I = State.get(Def, Part);
4089 ZExtInst *Inst = dyn_cast<ZExtInst>(I);
4090 if (Inst && Inst->use_empty()) {
4091 Value *NewI = Inst->getOperand(0);
4092 Inst->eraseFromParent();
4093 State.reset(Def, NewI, Part);
4094 }
4095 }
4096 }
4097}
4098
4099void InnerLoopVectorizer::fixVectorizedLoop(VPTransformState &State) {
4100 // Insert truncates and extends for any truncated instructions as hints to
4101 // InstCombine.
4102 if (VF.isVector())
4103 truncateToMinimalBitwidths(State);
4104
4105 // Fix widened non-induction PHIs by setting up the PHI operands.
4106 if (OrigPHIsToFix.size()) {
4107 assert(EnableVPlanNativePath &&((void)0)
4108 "Unexpected non-induction PHIs for fixup in non VPlan-native path")((void)0);
4109 fixNonInductionPHIs(State);
4110 }
4111
4112 // At this point every instruction in the original loop is widened to a
4113 // vector form. Now we need to fix the recurrences in the loop. These PHI
4114 // nodes are currently empty because we did not want to introduce cycles.
4115 // This is the second stage of vectorizing recurrences.
4116 fixCrossIterationPHIs(State);
4117
4118 // Forget the original basic block.
4119 PSE.getSE()->forgetLoop(OrigLoop);
4120
4121 // If we inserted an edge from the middle block to the unique exit block,
4122 // update uses outside the loop (phis) to account for the newly inserted
4123 // edge.
4124 if (!Cost->requiresScalarEpilogue(VF)) {
4125 // Fix-up external users of the induction variables.
4126 for (auto &Entry : Legal->getInductionVars())
4127 fixupIVUsers(Entry.first, Entry.second,
4128 getOrCreateVectorTripCount(LI->getLoopFor(LoopVectorBody)),
4129 IVEndValues[Entry.first], LoopMiddleBlock);
4130
4131 fixLCSSAPHIs(State);
4132 }
4133
4134 for (Instruction *PI : PredicatedInstructions)
4135 sinkScalarOperands(&*PI);
4136
4137 // Remove redundant induction instructions.
4138 cse(LoopVectorBody);
4139
4140 // Set/update profile weights for the vector and remainder loops as original
4141 // loop iterations are now distributed among them. Note that original loop
4142 // represented by LoopScalarBody becomes remainder loop after vectorization.
4143 //
4144 // For cases like foldTailByMasking() and requiresScalarEpiloque() we may
4145 // end up getting slightly roughened result but that should be OK since
4146 // profile is not inherently precise anyway. Note also possible bypass of
4147 // vector code caused by legality checks is ignored, assigning all the weight
4148 // to the vector loop, optimistically.
4149 //
4150 // For scalable vectorization we can't know at compile time how many iterations
4151 // of the loop are handled in one vector iteration, so instead assume a pessimistic
4152 // vscale of '1'.
4153 setProfileInfoAfterUnrolling(
4154 LI->getLoopFor(LoopScalarBody), LI->getLoopFor(LoopVectorBody),
4155 LI->getLoopFor(LoopScalarBody), VF.getKnownMinValue() * UF);
4156}
4157
4158void InnerLoopVectorizer::fixCrossIterationPHIs(VPTransformState &State) {
4159 // In order to support recurrences we need to be able to vectorize Phi nodes.
4160 // Phi nodes have cycles, so we need to vectorize them in two stages. This is
4161 // stage #2: We now need to fix the recurrences by adding incoming edges to
4162 // the currently empty PHI nodes. At this point every instruction in the
4163 // original loop is widened to a vector form so we can use them to construct
4164 // the incoming edges.
4165 VPBasicBlock *Header = State.Plan->getEntry()->getEntryBasicBlock();
4166 for (VPRecipeBase &R : Header->phis()) {
4167 if (auto *ReductionPhi = dyn_cast<VPReductionPHIRecipe>(&R))
4168 fixReduction(ReductionPhi, State);
4169 else if (auto *FOR = dyn_cast<VPFirstOrderRecurrencePHIRecipe>(&R))
4170 fixFirstOrderRecurrence(FOR, State);
4171 }
4172}
4173
4174void InnerLoopVectorizer::fixFirstOrderRecurrence(VPWidenPHIRecipe *PhiR,
4175 VPTransformState &State) {
4176 // This is the second phase of vectorizing first-order recurrences. An
4177 // overview of the transformation is described below. Suppose we have the
4178 // following loop.
4179 //
4180 // for (int i = 0; i < n; ++i)
4181 // b[i] = a[i] - a[i - 1];
4182 //
4183 // There is a first-order recurrence on "a". For this loop, the shorthand
4184 // scalar IR looks like:
4185 //
4186 // scalar.ph:
4187 // s_init = a[-1]
4188 // br scalar.body
4189 //
4190 // scalar.body:
4191 // i = phi [0, scalar.ph], [i+1, scalar.body]
4192 // s1 = phi [s_init, scalar.ph], [s2, scalar.body]
4193 // s2 = a[i]
4194 // b[i] = s2 - s1
4195 // br cond, scalar.body, ...
4196 //
4197 // In this example, s1 is a recurrence because it's value depends on the
4198 // previous iteration. In the first phase of vectorization, we created a
4199 // vector phi v1 for s1. We now complete the vectorization and produce the
4200 // shorthand vector IR shown below (for VF = 4, UF = 1).
4201 //
4202 // vector.ph:
4203 // v_init = vector(..., ..., ..., a[-1])
4204 // br vector.body
4205 //
4206 // vector.body
4207 // i = phi [0, vector.ph], [i+4, vector.body]
4208 // v1 = phi [v_init, vector.ph], [v2, vector.body]
4209 // v2 = a[i, i+1, i+2, i+3];
4210 // v3 = vector(v1(3), v2(0, 1, 2))
4211 // b[i, i+1, i+2, i+3] = v2 - v3
4212 // br cond, vector.body, middle.block
4213 //
4214 // middle.block:
4215 // x = v2(3)
4216 // br scalar.ph
4217 //
4218 // scalar.ph:
4219 // s_init = phi [x, middle.block], [a[-1], otherwise]
4220 // br scalar.body
4221 //
4222 // After execution completes the vector loop, we extract the next value of
4223 // the recurrence (x) to use as the initial value in the scalar loop.
4224
4225 auto *IdxTy = Builder.getInt32Ty();
4226 auto *VecPhi = cast<PHINode>(State.get(PhiR, 0));
4227
4228 // Fix the latch value of the new recurrence in the vector loop.
4229 VPValue *PreviousDef = PhiR->getBackedgeValue();
4230 Value *Incoming = State.get(PreviousDef, UF - 1);
4231 VecPhi->addIncoming(Incoming, LI->getLoopFor(LoopVectorBody)->getLoopLatch());
4232
4233 // Extract the last vector element in the middle block. This will be the
4234 // initial value for the recurrence when jumping to the scalar loop.
4235 auto *ExtractForScalar = Incoming;
4236 if (VF.isVector()) {
4237 auto *One = ConstantInt::get(IdxTy, 1);
4238 Builder.SetInsertPoint(LoopMiddleBlock->getTerminator());
4239 auto *RuntimeVF = getRuntimeVF(Builder, IdxTy, VF);
4240 auto *LastIdx = Builder.CreateSub(RuntimeVF, One);
4241 ExtractForScalar = Builder.CreateExtractElement(ExtractForScalar, LastIdx,
4242 "vector.recur.extract");
4243 }
4244 // Extract the second last element in the middle block if the
4245 // Phi is used outside the loop. We need to extract the phi itself
4246 // and not the last element (the phi update in the current iteration). This
4247 // will be the value when jumping to the exit block from the LoopMiddleBlock,
4248 // when the scalar loop is not run at all.
4249 Value *ExtractForPhiUsedOutsideLoop = nullptr;
4250 if (VF.isVector()) {
4251 auto *RuntimeVF = getRuntimeVF(Builder, IdxTy, VF);
4252 auto *Idx = Builder.CreateSub(RuntimeVF, ConstantInt::get(IdxTy, 2));
4253 ExtractForPhiUsedOutsideLoop = Builder.CreateExtractElement(
4254 Incoming, Idx, "vector.recur.extract.for.phi");
4255 } else if (UF > 1)
4256 // When loop is unrolled without vectorizing, initialize
4257 // ExtractForPhiUsedOutsideLoop with the value just prior to unrolled value
4258 // of `Incoming`. This is analogous to the vectorized case above: extracting
4259 // the second last element when VF > 1.
4260 ExtractForPhiUsedOutsideLoop = State.get(PreviousDef, UF - 2);
4261
4262 // Fix the initial value of the original recurrence in the scalar loop.
4263 Builder.SetInsertPoint(&*LoopScalarPreHeader->begin());
4264 PHINode *Phi = cast<PHINode>(PhiR->getUnderlyingValue());
4265 auto *Start = Builder.CreatePHI(Phi->getType(), 2, "scalar.recur.init");
4266 auto *ScalarInit = PhiR->getStartValue()->getLiveInIRValue();
4267 for (auto *BB : predecessors(LoopScalarPreHeader)) {
4268 auto *Incoming = BB == LoopMiddleBlock ? ExtractForScalar : ScalarInit;
4269 Start->addIncoming(Incoming, BB);
4270 }
4271
4272 Phi->setIncomingValueForBlock(LoopScalarPreHeader, Start);
4273 Phi->setName("scalar.recur");
4274
4275 // Finally, fix users of the recurrence outside the loop. The users will need
4276 // either the last value of the scalar recurrence or the last value of the
4277 // vector recurrence we extracted in the middle block. Since the loop is in
4278 // LCSSA form, we just need to find all the phi nodes for the original scalar
4279 // recurrence in the exit block, and then add an edge for the middle block.
4280 // Note that LCSSA does not imply single entry when the original scalar loop
4281 // had multiple exiting edges (as we always run the last iteration in the
4282 // scalar epilogue); in that case, there is no edge from middle to exit and
4283 // and thus no phis which needed updated.
4284 if (!Cost->requiresScalarEpilogue(VF))
4285 for (PHINode &LCSSAPhi : LoopExitBlock->phis())
4286 if (any_of(LCSSAPhi.incoming_values(),
4287 [Phi](Value *V) { return V == Phi; }))
4288 LCSSAPhi.addIncoming(ExtractForPhiUsedOutsideLoop, LoopMiddleBlock);
4289}
4290
4291void InnerLoopVectorizer::fixReduction(VPReductionPHIRecipe *PhiR,
4292 VPTransformState &State) {
4293 PHINode *OrigPhi = cast<PHINode>(PhiR->getUnderlyingValue());
4294 // Get it's reduction variable descriptor.
4295 assert(Legal->isReductionVariable(OrigPhi) &&((void)0)
4296 "Unable to find the reduction variable")((void)0);
4297 const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor();
4298
4299 RecurKind RK = RdxDesc.getRecurrenceKind();
4300 TrackingVH<Value> ReductionStartValue = RdxDesc.getRecurrenceStartValue();
4301 Instruction *LoopExitInst = RdxDesc.getLoopExitInstr();
4302 setDebugLocFromInst(ReductionStartValue);
4303
4304 VPValue *LoopExitInstDef = State.Plan->getVPValue(LoopExitInst);
4305 // This is the vector-clone of the value that leaves the loop.
4306 Type *VecTy = State.get(LoopExitInstDef, 0)->getType();
4307
4308 // Wrap flags are in general invalid after vectorization, clear them.
4309 clearReductionWrapFlags(RdxDesc, State);
4310
4311 // Fix the vector-loop phi.
4312
4313 // Reductions do not have to start at zero. They can start with
4314 // any loop invariant values.
4315 BasicBlock *VectorLoopLatch = LI->getLoopFor(LoopVectorBody)->getLoopLatch();
4316
4317 unsigned LastPartForNewPhi = PhiR->isOrdered() ? 1 : UF;
4318 for (unsigned Part = 0; Part < LastPartForNewPhi; ++Part) {
4319 Value *VecRdxPhi = State.get(PhiR->getVPSingleValue(), Part);
4320 Value *Val = State.get(PhiR->getBackedgeValue(), Part);
4321 if (PhiR->isOrdered())
4322 Val = State.get(PhiR->getBackedgeValue(), UF - 1);
4323
4324 cast<PHINode>(VecRdxPhi)->addIncoming(Val, VectorLoopLatch);
4325 }
4326
4327 // Before each round, move the insertion point right between
4328 // the PHIs and the values we are going to write.
4329 // This allows us to write both PHINodes and the extractelement
4330 // instructions.
4331 Builder.SetInsertPoint(&*LoopMiddleBlock->getFirstInsertionPt());
4332
4333 setDebugLocFromInst(LoopExitInst);
4334
4335 Type *PhiTy = OrigPhi->getType();
4336 // If tail is folded by masking, the vector value to leave the loop should be
4337 // a Select choosing between the vectorized LoopExitInst and vectorized Phi,
4338 // instead of the former. For an inloop reduction the reduction will already
4339 // be predicated, and does not need to be handled here.
4340 if (Cost->foldTailByMasking() && !PhiR->isInLoop()) {
4341 for (unsigned Part = 0; Part < UF; ++Part) {
4342 Value *VecLoopExitInst = State.get(LoopExitInstDef, Part);
4343 Value *Sel = nullptr;
4344 for (User *U : VecLoopExitInst->users()) {
4345 if (isa<SelectInst>(U)) {
4346 assert(!Sel && "Reduction exit feeding two selects")((void)0);
4347 Sel = U;
4348 } else
4349 assert(isa<PHINode>(U) && "Reduction exit must feed Phi's or select")((void)0);
4350 }
4351 assert(Sel && "Reduction exit feeds no select")((void)0);
4352 State.reset(LoopExitInstDef, Sel, Part);
4353
4354 // If the target can create a predicated operator for the reduction at no
4355 // extra cost in the loop (for example a predicated vadd), it can be
4356 // cheaper for the select to remain in the loop than be sunk out of it,
4357 // and so use the select value for the phi instead of the old
4358 // LoopExitValue.
4359 if (PreferPredicatedReductionSelect ||
4360 TTI->preferPredicatedReductionSelect(
4361 RdxDesc.getOpcode(), PhiTy,
4362 TargetTransformInfo::ReductionFlags())) {
4363 auto *VecRdxPhi =
4364 cast<PHINode>(State.get(PhiR->getVPSingleValue(), Part));
4365 VecRdxPhi->setIncomingValueForBlock(
4366 LI->getLoopFor(LoopVectorBody)->getLoopLatch(), Sel);
4367 }
4368 }
4369 }
4370
4371 // If the vector reduction can be performed in a smaller type, we truncate
4372 // then extend the loop exit value to enable InstCombine to evaluate the
4373 // entire expression in the smaller type.
4374 if (VF.isVector() && PhiTy != RdxDesc.getRecurrenceType()) {
4375 assert(!PhiR->isInLoop() && "Unexpected truncated inloop reduction!")((void)0);
4376 Type *RdxVecTy = VectorType::get(RdxDesc.getRecurrenceType(), VF);
4377 Builder.SetInsertPoint(
4378 LI->getLoopFor(LoopVectorBody)->getLoopLatch()->getTerminator());
4379 VectorParts RdxParts(UF);
4380 for (unsigned Part = 0; Part < UF; ++Part) {
4381 RdxParts[Part] = State.get(LoopExitInstDef, Part);
4382 Value *Trunc = Builder.CreateTrunc(RdxParts[Part], RdxVecTy);
4383 Value *Extnd = RdxDesc.isSigned() ? Builder.CreateSExt(Trunc, VecTy)
4384 : Builder.CreateZExt(Trunc, VecTy);
4385 for (Value::user_iterator UI = RdxParts[Part]->user_begin();
4386 UI != RdxParts[Part]->user_end();)
4387 if (*UI != Trunc) {
4388 (*UI++)->replaceUsesOfWith(RdxParts[Part], Extnd);
4389 RdxParts[Part] = Extnd;
4390 } else {
4391 ++UI;
4392 }
4393 }
4394 Builder.SetInsertPoint(&*LoopMiddleBlock->getFirstInsertionPt());
4395 for (unsigned Part = 0; Part < UF; ++Part) {
4396 RdxParts[Part] = Builder.CreateTrunc(RdxParts[Part], RdxVecTy);
4397 State.reset(LoopExitInstDef, RdxParts[Part], Part);
4398 }
4399 }
4400
4401 // Reduce all of the unrolled parts into a single vector.
4402 Value *ReducedPartRdx = State.get(LoopExitInstDef, 0);
4403 unsigned Op = RecurrenceDescriptor::getOpcode(RK);
4404
4405 // The middle block terminator has already been assigned a DebugLoc here (the
4406 // OrigLoop's single latch terminator). We want the whole middle block to
4407 // appear to execute on this line because: (a) it is all compiler generated,
4408 // (b) these instructions are always executed after evaluating the latch
4409 // conditional branch, and (c) other passes may add new predecessors which
4410 // terminate on this line. This is the easiest way to ensure we don't
4411 // accidentally cause an extra step back into the loop while debugging.
4412 setDebugLocFromInst(LoopMiddleBlock->getTerminator());
4413 if (PhiR->isOrdered())
4414 ReducedPartRdx = State.get(LoopExitInstDef, UF - 1);
4415 else {
4416 // Floating-point operations should have some FMF to enable the reduction.
4417 IRBuilderBase::FastMathFlagGuard FMFG(Builder);
4418 Builder.setFastMathFlags(RdxDesc.getFastMathFlags());
4419 for (unsigned Part = 1; Part < UF; ++Part) {
4420 Value *RdxPart = State.get(LoopExitInstDef, Part);
4421 if (Op != Instruction::ICmp && Op != Instruction::FCmp) {
4422 ReducedPartRdx = Builder.CreateBinOp(
4423 (Instruction::BinaryOps)Op, RdxPart, ReducedPartRdx, "bin.rdx");
4424 } else {
4425 ReducedPartRdx = createMinMaxOp(Builder, RK, ReducedPartRdx, RdxPart);
4426 }
4427 }
4428 }
4429
4430 // Create the reduction after the loop. Note that inloop reductions create the
4431 // target reduction in the loop using a Reduction recipe.
4432 if (VF.isVector() && !PhiR->isInLoop()) {
4433 ReducedPartRdx =
4434 createTargetReduction(Builder, TTI, RdxDesc, ReducedPartRdx);
4435 // If the reduction can be performed in a smaller type, we need to extend
4436 // the reduction to the wider type before we branch to the original loop.
4437 if (PhiTy != RdxDesc.getRecurrenceType())
4438 ReducedPartRdx = RdxDesc.isSigned()
4439 ? Builder.CreateSExt(ReducedPartRdx, PhiTy)
4440 : Builder.CreateZExt(ReducedPartRdx, PhiTy);
4441 }
4442
4443 // Create a phi node that merges control-flow from the backedge-taken check
4444 // block and the middle block.
4445 PHINode *BCBlockPhi = PHINode::Create(PhiTy, 2, "bc.merge.rdx",
4446 LoopScalarPreHeader->getTerminator());
4447 for (unsigned I = 0, E = LoopBypassBlocks.size(); I != E; ++I)
4448 BCBlockPhi->addIncoming(ReductionStartValue, LoopBypassBlocks[I]);
4449 BCBlockPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock);
4450
4451 // Now, we need to fix the users of the reduction variable
4452 // inside and outside of the scalar remainder loop.
4453
4454 // We know that the loop is in LCSSA form. We need to update the PHI nodes
4455 // in the exit blocks. See comment on analogous loop in
4456 // fixFirstOrderRecurrence for a more complete explaination of the logic.
4457 if (!Cost->requiresScalarEpilogue(VF))
4458 for (PHINode &LCSSAPhi : LoopExitBlock->phis())
4459 if (any_of(LCSSAPhi.incoming_values(),
4460 [LoopExitInst](Value *V) { return V == LoopExitInst; }))
4461 LCSSAPhi.addIncoming(ReducedPartRdx, LoopMiddleBlock);
4462
4463 // Fix the scalar loop reduction variable with the incoming reduction sum
4464 // from the vector body and from the backedge value.
4465 int IncomingEdgeBlockIdx =
4466 OrigPhi->getBasicBlockIndex(OrigLoop->getLoopLatch());
4467 assert(IncomingEdgeBlockIdx >= 0 && "Invalid block index")((void)0);
4468 // Pick the other block.
4469 int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1);
4470 OrigPhi->setIncomingValue(SelfEdgeBlockIdx, BCBlockPhi);
4471 OrigPhi->setIncomingValue(IncomingEdgeBlockIdx, LoopExitInst);
4472}
4473
4474void InnerLoopVectorizer::clearReductionWrapFlags(const RecurrenceDescriptor &RdxDesc,
4475 VPTransformState &State) {
4476 RecurKind RK = RdxDesc.getRecurrenceKind();
4477 if (RK != RecurKind::Add && RK != RecurKind::Mul)
4478 return;
4479
4480 Instruction *LoopExitInstr = RdxDesc.getLoopExitInstr();
4481 assert(LoopExitInstr && "null loop exit instruction")((void)0);
4482 SmallVector<Instruction *, 8> Worklist;
4483 SmallPtrSet<Instruction *, 8> Visited;
4484 Worklist.push_back(LoopExitInstr);
4485 Visited.insert(LoopExitInstr);
4486
4487 while (!Worklist.empty()) {
4488 Instruction *Cur = Worklist.pop_back_val();
4489 if (isa<OverflowingBinaryOperator>(Cur))
4490 for (unsigned Part = 0; Part < UF; ++Part) {
4491 Value *V = State.get(State.Plan->getVPValue(Cur), Part);
4492 cast<Instruction>(V)->dropPoisonGeneratingFlags();
4493 }
4494
4495 for (User *U : Cur->users()) {
4496 Instruction *UI = cast<Instruction>(U);
4497 if ((Cur != LoopExitInstr || OrigLoop->contains(UI->getParent())) &&
4498 Visited.insert(UI).second)
4499 Worklist.push_back(UI);
4500 }
4501 }
4502}
4503
4504void InnerLoopVectorizer::fixLCSSAPHIs(VPTransformState &State) {
4505 for (PHINode &LCSSAPhi : LoopExitBlock->phis()) {
4506 if (LCSSAPhi.getBasicBlockIndex(LoopMiddleBlock) != -1)
4507 // Some phis were already hand updated by the reduction and recurrence
4508 // code above, leave them alone.
4509 continue;
4510
4511 auto *IncomingValue = LCSSAPhi.getIncomingValue(0);
4512 // Non-instruction incoming values will have only one value.
4513
4514 VPLane Lane = VPLane::getFirstLane();
4515 if (isa<Instruction>(IncomingValue) &&
4516 !Cost->isUniformAfterVectorization(cast<Instruction>(IncomingValue),
4517 VF))
4518 Lane = VPLane::getLastLaneForVF(VF);
4519
4520 // Can be a loop invariant incoming value or the last scalar value to be
4521 // extracted from the vectorized loop.
4522 Builder.SetInsertPoint(LoopMiddleBlock->getTerminator());
4523 Value *lastIncomingValue =
4524 OrigLoop->isLoopInvariant(IncomingValue)
4525 ? IncomingValue
4526 : State.get(State.Plan->getVPValue(IncomingValue),
4527 VPIteration(UF - 1, Lane));
4528 LCSSAPhi.addIncoming(lastIncomingValue, LoopMiddleBlock);
4529 }
4530}
4531
4532void InnerLoopVectorizer::sinkScalarOperands(Instruction *PredInst) {
4533 // The basic block and loop containing the predicated instruction.
4534 auto *PredBB = PredInst->getParent();
4535 auto *VectorLoop = LI->getLoopFor(PredBB);
4536
4537 // Initialize a worklist with the operands of the predicated instruction.
4538 SetVector<Value *> Worklist(PredInst->op_begin(), PredInst->op_end());
4539
4540 // Holds instructions that we need to analyze again. An instruction may be
4541 // reanalyzed if we don't yet know if we can sink it or not.
4542 SmallVector<Instruction *, 8> InstsToReanalyze;
4543
4544 // Returns true if a given use occurs in the predicated block. Phi nodes use
4545 // their operands in their corresponding predecessor blocks.
4546 auto isBlockOfUsePredicated = [&](Use &U) -> bool {
4547 auto *I = cast<Instruction>(U.getUser());
4548 BasicBlock *BB = I->getParent();
4549 if (auto *Phi = dyn_cast<PHINode>(I))
4550 BB = Phi->getIncomingBlock(
4551 PHINode::getIncomingValueNumForOperand(U.getOperandNo()));
4552 return BB == PredBB;
4553 };
4554
4555 // Iteratively sink the scalarized operands of the predicated instruction
4556 // into the block we created for it. When an instruction is sunk, it's
4557 // operands are then added to the worklist. The algorithm ends after one pass
4558 // through the worklist doesn't sink a single instruction.
4559 bool Changed;
4560 do {
4561 // Add the instructions that need to be reanalyzed to the worklist, and
4562 // reset the changed indicator.
4563 Worklist.insert(InstsToReanalyze.begin(), InstsToReanalyze.end());
4564 InstsToReanalyze.clear();
4565 Changed = false;
4566
4567 while (!Worklist.empty()) {
4568 auto *I = dyn_cast<Instruction>(Worklist.pop_back_val());
4569
4570 // We can't sink an instruction if it is a phi node, is not in the loop,
4571 // or may have side effects.
4572 if (!I || isa<PHINode>(I) || !VectorLoop->contains(I) ||
4573 I->mayHaveSideEffects())
4574 continue;
4575
4576 // If the instruction is already in PredBB, check if we can sink its
4577 // operands. In that case, VPlan's sinkScalarOperands() succeeded in
4578 // sinking the scalar instruction I, hence it appears in PredBB; but it
4579 // may have failed to sink I's operands (recursively), which we try
4580 // (again) here.
4581 if (I->getParent() == PredBB) {
4582 Worklist.insert(I->op_begin(), I->op_end());
4583 continue;
4584 }
4585
4586 // It's legal to sink the instruction if all its uses occur in the
4587 // predicated block. Otherwise, there's nothing to do yet, and we may
4588 // need to reanalyze the instruction.
4589 if (!llvm::all_of(I->uses(), isBlockOfUsePredicated)) {
4590 InstsToReanalyze.push_back(I);
4591 continue;
4592 }
4593
4594 // Move the instruction to the beginning of the predicated block, and add
4595 // it's operands to the worklist.
4596 I->moveBefore(&*PredBB->getFirstInsertionPt());
4597 Worklist.insert(I->op_begin(), I->op_end());
4598
4599 // The sinking may have enabled other instructions to be sunk, so we will
4600 // need to iterate.
4601 Changed = true;
4602 }
4603 } while (Changed);
4604}
4605
4606void InnerLoopVectorizer::fixNonInductionPHIs(VPTransformState &State) {
4607 for (PHINode *OrigPhi : OrigPHIsToFix) {
4608 VPWidenPHIRecipe *VPPhi =
4609 cast<VPWidenPHIRecipe>(State.Plan->getVPValue(OrigPhi));
4610 PHINode *NewPhi = cast<PHINode>(State.get(VPPhi, 0));
4611 // Make sure the builder has a valid insert point.
4612 Builder.SetInsertPoint(NewPhi);
4613 for (unsigned i = 0; i < VPPhi->getNumOperands(); ++i) {
4614 VPValue *Inc = VPPhi->getIncomingValue(i);
4615 VPBasicBlock *VPBB = VPPhi->getIncomingBlock(i);
4616 NewPhi->addIncoming(State.get(Inc, 0), State.CFG.VPBB2IRBB[VPBB]);
4617 }
4618 }
4619}
4620
4621bool InnerLoopVectorizer::useOrderedReductions(RecurrenceDescriptor &RdxDesc) {
4622 return Cost->useOrderedReductions(RdxDesc);
4623}
4624
4625void InnerLoopVectorizer::widenGEP(GetElementPtrInst *GEP, VPValue *VPDef,
4626 VPUser &Operands, unsigned UF,
4627 ElementCount VF, bool IsPtrLoopInvariant,
4628 SmallBitVector &IsIndexLoopInvariant,
4629 VPTransformState &State) {
4630 // Construct a vector GEP by widening the operands of the scalar GEP as
4631 // necessary. We mark the vector GEP 'inbounds' if appropriate. A GEP
4632 // results in a vector of pointers when at least one operand of the GEP
4633 // is vector-typed. Thus, to keep the representation compact, we only use
4634 // vector-typed operands for loop-varying values.
4635
4636 if (VF.isVector() && IsPtrLoopInvariant && IsIndexLoopInvariant.all()) {
4637 // If we are vectorizing, but the GEP has only loop-invariant operands,
4638 // the GEP we build (by only using vector-typed operands for
4639 // loop-varying values) would be a scalar pointer. Thus, to ensure we
4640 // produce a vector of pointers, we need to either arbitrarily pick an
4641 // operand to broadcast, or broadcast a clone of the original GEP.
4642 // Here, we broadcast a clone of the original.
4643 //
4644 // TODO: If at some point we decide to scalarize instructions having
4645 // loop-invariant operands, this special case will no longer be
4646 // required. We would add the scalarization decision to
4647 // collectLoopScalars() and teach getVectorValue() to broadcast
4648 // the lane-zero scalar value.
4649 auto *Clone = Builder.Insert(GEP->clone());
4650 for (unsigned Part = 0; Part < UF; ++Part) {
4651 Value *EntryPart = Builder.CreateVectorSplat(VF, Clone);
4652 State.set(VPDef, EntryPart, Part);
4653 addMetadata(EntryPart, GEP);
4654 }
4655 } else {
4656 // If the GEP has at least one loop-varying operand, we are sure to
4657 // produce a vector of pointers. But if we are only unrolling, we want
4658 // to produce a scalar GEP for each unroll part. Thus, the GEP we
4659 // produce with the code below will be scalar (if VF == 1) or vector
4660 // (otherwise). Note that for the unroll-only case, we still maintain
4661 // values in the vector mapping with initVector, as we do for other
4662 // instructions.
4663 for (unsigned Part = 0; Part < UF; ++Part) {
4664 // The pointer operand of the new GEP. If it's loop-invariant, we
4665 // won't broadcast it.
4666 auto *Ptr = IsPtrLoopInvariant
4667 ? State.get(Operands.getOperand(0), VPIteration(0, 0))
4668 : State.get(Operands.getOperand(0), Part);
4669
4670 // Collect all the indices for the new GEP. If any index is
4671 // loop-invariant, we won't broadcast it.
4672 SmallVector<Value *, 4> Indices;
4673 for (unsigned I = 1, E = Operands.getNumOperands(); I < E; I++) {
4674 VPValue *Operand = Operands.getOperand(I);
4675 if (IsIndexLoopInvariant[I - 1])
4676 Indices.push_back(State.get(Operand, VPIteration(0, 0)));
4677 else
4678 Indices.push_back(State.get(Operand, Part));
4679 }
4680
4681 // Create the new GEP. Note that this GEP may be a scalar if VF == 1,
4682 // but it should be a vector, otherwise.
4683 auto *NewGEP =
4684 GEP->isInBounds()
4685 ? Builder.CreateInBoundsGEP(GEP->getSourceElementType(), Ptr,
4686 Indices)
4687 : Builder.CreateGEP(GEP->getSourceElementType(), Ptr, Indices);
4688 assert((VF.isScalar() || NewGEP->getType()->isVectorTy()) &&((void)0)
4689 "NewGEP is not a pointer vector")((void)0);
4690 State.set(VPDef, NewGEP, Part);
4691 addMetadata(NewGEP, GEP);
4692 }
4693 }
4694}
4695
4696void InnerLoopVectorizer::widenPHIInstruction(Instruction *PN,
4697 VPWidenPHIRecipe *PhiR,
4698 VPTransformState &State) {
4699 PHINode *P = cast<PHINode>(PN);
4700 if (EnableVPlanNativePath) {
4701 // Currently we enter here in the VPlan-native path for non-induction
4702 // PHIs where all control flow is uniform. We simply widen these PHIs.
4703 // Create a vector phi with no operands - the vector phi operands will be
4704 // set at the end of vector code generation.
4705 Type *VecTy = (State.VF.isScalar())
4706 ? PN->getType()
4707 : VectorType::get(PN->getType(), State.VF);
4708 Value *VecPhi = Builder.CreatePHI(VecTy, PN->getNumOperands(), "vec.phi");
4709 State.set(PhiR, VecPhi, 0);
4710 OrigPHIsToFix.push_back(P);
4711
4712 return;
4713 }
4714
4715 assert(PN->getParent() == OrigLoop->getHeader() &&((void)0)
4716 "Non-header phis should have been handled elsewhere")((void)0);
4717
4718 // In order to support recurrences we need to be able to vectorize Phi nodes.
4719 // Phi nodes have cycles, so we need to vectorize them in two stages. This is
4720 // stage #1: We create a new vector PHI node with no incoming edges. We'll use
4721 // this value when we vectorize all of the instructions that use the PHI.
4722
4723 assert(!Legal->isReductionVariable(P) &&((void)0)
4724 "reductions should be handled elsewhere")((void)0);
4725
4726 setDebugLocFromInst(P);
4727
4728 // This PHINode must be an induction variable.
4729 // Make sure that we know about it.
4730 assert(Legal->getInductionVars().count(P) && "Not an induction variable")((void)0);
4731
4732 InductionDescriptor II = Legal->getInductionVars().lookup(P);
4733 const DataLayout &DL = OrigLoop->getHeader()->getModule()->getDataLayout();
4734
4735 // FIXME: The newly created binary instructions should contain nsw/nuw flags,
4736 // which can be found from the original scalar operations.
4737 switch (II.getKind()) {
4738 case InductionDescriptor::IK_NoInduction:
4739 llvm_unreachable("Unknown induction")__builtin_unreachable();
4740 case InductionDescriptor::IK_IntInduction:
4741 case InductionDescriptor::IK_FpInduction:
4742 llvm_unreachable("Integer/fp induction is handled elsewhere.")__builtin_unreachable();
4743 case InductionDescriptor::IK_PtrInduction: {
4744 // Handle the pointer induction variable case.
4745 assert(P->getType()->isPointerTy() && "Unexpected type.")((void)0);
4746
4747 if (Cost->isScalarAfterVectorization(P, State.VF)) {
4748 // This is the normalized GEP that starts counting at zero.
4749 Value *PtrInd =
4750 Builder.CreateSExtOrTrunc(Induction, II.getStep()->getType());
4751 // Determine the number of scalars we need to generate for each unroll
4752 // iteration. If the instruction is uniform, we only need to generate the
4753 // first lane. Otherwise, we generate all VF values.
4754 bool IsUniform = Cost->isUniformAfterVectorization(P, State.VF);
4755 unsigned Lanes = IsUniform ? 1 : State.VF.getKnownMinValue();
4756
4757 bool NeedsVectorIndex = !IsUniform && VF.isScalable();
4758 Value *UnitStepVec = nullptr, *PtrIndSplat = nullptr;
4759 if (NeedsVectorIndex) {
4760 Type *VecIVTy = VectorType::get(PtrInd->getType(), VF);
4761 UnitStepVec = Builder.CreateStepVector(VecIVTy);
4762 PtrIndSplat = Builder.CreateVectorSplat(VF, PtrInd);
4763 }
4764
4765 for (unsigned Part = 0; Part < UF; ++Part) {
4766 Value *PartStart = createStepForVF(
4767 Builder, ConstantInt::get(PtrInd->getType(), Part), VF);
4768
4769 if (NeedsVectorIndex) {
4770 Value *PartStartSplat = Builder.CreateVectorSplat(VF, PartStart);
4771 Value *Indices = Builder.CreateAdd(PartStartSplat, UnitStepVec);
4772 Value *GlobalIndices = Builder.CreateAdd(PtrIndSplat, Indices);
4773 Value *SclrGep =
4774 emitTransformedIndex(Builder, GlobalIndices, PSE.getSE(), DL, II);
4775 SclrGep->setName("next.gep");
4776 State.set(PhiR, SclrGep, Part);
4777 // We've cached the whole vector, which means we can support the
4778 // extraction of any lane.
4779 continue;
4780 }
4781
4782 for (unsigned Lane = 0; Lane < Lanes; ++Lane) {
4783 Value *Idx = Builder.CreateAdd(
4784 PartStart, ConstantInt::get(PtrInd->getType(), Lane));
4785 Value *GlobalIdx = Builder.CreateAdd(PtrInd, Idx);
4786 Value *SclrGep =
4787 emitTransformedIndex(Builder, GlobalIdx, PSE.getSE(), DL, II);
4788 SclrGep->setName("next.gep");
4789 State.set(PhiR, SclrGep, VPIteration(Part, Lane));
4790 }
4791 }
4792 return;
4793 }
4794 assert(isa<SCEVConstant>(II.getStep()) &&((void)0)
4795 "Induction step not a SCEV constant!")((void)0);
4796 Type *PhiType = II.getStep()->getType();
4797
4798 // Build a pointer phi
4799 Value *ScalarStartValue = II.getStartValue();
4800 Type *ScStValueType = ScalarStartValue->getType();
4801 PHINode *NewPointerPhi =
4802 PHINode::Create(ScStValueType, 2, "pointer.phi", Induction);
4803 NewPointerPhi->addIncoming(ScalarStartValue, LoopVectorPreHeader);
4804
4805 // A pointer induction, performed by using a gep
4806 BasicBlock *LoopLatch = LI->getLoopFor(LoopVectorBody)->getLoopLatch();
4807 Instruction *InductionLoc = LoopLatch->getTerminator();
4808 const SCEV *ScalarStep = II.getStep();
4809 SCEVExpander Exp(*PSE.getSE(), DL, "induction");
4810 Value *ScalarStepValue =
4811 Exp.expandCodeFor(ScalarStep, PhiType, InductionLoc);
4812 Value *RuntimeVF = getRuntimeVF(Builder, PhiType, VF);
4813 Value *NumUnrolledElems =
4814 Builder.CreateMul(RuntimeVF, ConstantInt::get(PhiType, State.UF));
4815 Value *InductionGEP = GetElementPtrInst::Create(
4816 ScStValueType->getPointerElementType(), NewPointerPhi,
4817 Builder.CreateMul(ScalarStepValue, NumUnrolledElems), "ptr.ind",
4818 InductionLoc);
4819 NewPointerPhi->addIncoming(InductionGEP, LoopLatch);
4820
4821 // Create UF many actual address geps that use the pointer
4822 // phi as base and a vectorized version of the step value
4823 // (<step*0, ..., step*N>) as offset.
4824 for (unsigned Part = 0; Part < State.UF; ++Part) {
4825 Type *VecPhiType = VectorType::get(PhiType, State.VF);
4826 Value *StartOffsetScalar =
4827 Builder.CreateMul(RuntimeVF, ConstantInt::get(PhiType, Part));
4828 Value *StartOffset =
4829 Builder.CreateVectorSplat(State.VF, StartOffsetScalar);
4830 // Create a vector of consecutive numbers from zero to VF.
4831 StartOffset =
4832 Builder.CreateAdd(StartOffset, Builder.CreateStepVector(VecPhiType));
4833
4834 Value *GEP = Builder.CreateGEP(
4835 ScStValueType->getPointerElementType(), NewPointerPhi,
4836 Builder.CreateMul(
4837 StartOffset, Builder.CreateVectorSplat(State.VF, ScalarStepValue),
4838 "vector.gep"));
4839 State.set(PhiR, GEP, Part);
4840 }
4841 }
4842 }
4843}
4844
4845/// A helper function for checking whether an integer division-related
4846/// instruction may divide by zero (in which case it must be predicated if
4847/// executed conditionally in the scalar code).
4848/// TODO: It may be worthwhile to generalize and check isKnownNonZero().
4849/// Non-zero divisors that are non compile-time constants will not be
4850/// converted into multiplication, so we will still end up scalarizing
4851/// the division, but can do so w/o predication.
4852static bool mayDivideByZero(Instruction &I) {
4853 assert((I.getOpcode() == Instruction::UDiv ||((void)0)
4854 I.getOpcode() == Instruction::SDiv ||((void)0)
4855 I.getOpcode() == Instruction::URem ||((void)0)
4856 I.getOpcode() == Instruction::SRem) &&((void)0)
4857 "Unexpected instruction")((void)0);
4858 Value *Divisor = I.getOperand(1);
4859 auto *CInt = dyn_cast<ConstantInt>(Divisor);
4860 return !CInt || CInt->isZero();
4861}
4862
4863void InnerLoopVectorizer::widenInstruction(Instruction &I, VPValue *Def,
4864 VPUser &User,
4865 VPTransformState &State) {
4866 switch (I.getOpcode()) {
4867 case Instruction::Call:
4868 case Instruction::Br:
4869 case Instruction::PHI:
4870 case Instruction::GetElementPtr:
4871 case Instruction::Select:
4872 llvm_unreachable("This instruction is handled by a different recipe.")__builtin_unreachable();
4873 case Instruction::UDiv:
4874 case Instruction::SDiv:
4875 case Instruction::SRem:
4876 case Instruction::URem:
4877 case Instruction::Add:
4878 case Instruction::FAdd:
4879 case Instruction::Sub:
4880 case Instruction::FSub:
4881 case Instruction::FNeg:
4882 case Instruction::Mul:
4883 case Instruction::FMul:
4884 case Instruction::FDiv:
4885 case Instruction::FRem:
4886 case Instruction::Shl:
4887 case Instruction::LShr:
4888 case Instruction::AShr:
4889 case Instruction::And:
4890 case Instruction::Or:
4891 case Instruction::Xor: {
4892 // Just widen unops and binops.
4893 setDebugLocFromInst(&I);
4894
4895 for (unsigned Part = 0; Part < UF; ++Part) {
4896 SmallVector<Value *, 2> Ops;
4897 for (VPValue *VPOp : User.operands())
4898 Ops.push_back(State.get(VPOp, Part));
4899
4900 Value *V = Builder.CreateNAryOp(I.getOpcode(), Ops);
4901
4902 if (auto *VecOp = dyn_cast<Instruction>(V))
4903 VecOp->copyIRFlags(&I);
4904
4905 // Use this vector value for all users of the original instruction.
4906 State.set(Def, V, Part);
4907 addMetadata(V, &I);
4908 }
4909
4910 break;
4911 }
4912 case Instruction::ICmp:
4913 case Instruction::FCmp: {
4914 // Widen compares. Generate vector compares.
4915 bool FCmp = (I.getOpcode() == Instruction::FCmp);
4916 auto *Cmp = cast<CmpInst>(&I);
4917 setDebugLocFromInst(Cmp);
4918 for (unsigned Part = 0; Part < UF; ++Part) {
4919 Value *A = State.get(User.getOperand(0), Part);
4920 Value *B = State.get(User.getOperand(1), Part);
4921 Value *C = nullptr;
4922 if (FCmp) {
4923 // Propagate fast math flags.
4924 IRBuilder<>::FastMathFlagGuard FMFG(Builder);
4925 Builder.setFastMathFlags(Cmp->getFastMathFlags());
4926 C = Builder.CreateFCmp(Cmp->getPredicate(), A, B);
4927 } else {
4928 C = Builder.CreateICmp(Cmp->getPredicate(), A, B);
4929 }
4930 State.set(Def, C, Part);
4931 addMetadata(C, &I);
4932 }
4933
4934 break;
4935 }
4936
4937 case Instruction::ZExt:
4938 case Instruction::SExt:
4939 case Instruction::FPToUI:
4940 case Instruction::FPToSI:
4941 case Instruction::FPExt:
4942 case Instruction::PtrToInt:
4943 case Instruction::IntToPtr:
4944 case Instruction::SIToFP:
4945 case Instruction::UIToFP:
4946 case Instruction::Trunc:
4947 case Instruction::FPTrunc:
4948 case Instruction::BitCast: {
4949 auto *CI = cast<CastInst>(&I);
4950 setDebugLocFromInst(CI);
4951
4952 /// Vectorize casts.
4953 Type *DestTy =
4954 (VF.isScalar()) ? CI->getType() : VectorType::get(CI->getType(), VF);
4955
4956 for (unsigned Part = 0; Part < UF; ++Part) {
4957 Value *A = State.get(User.getOperand(0), Part);
4958 Value *Cast = Builder.CreateCast(CI->getOpcode(), A, DestTy);
4959 State.set(Def, Cast, Part);
4960 addMetadata(Cast, &I);
4961 }
4962 break;
4963 }
4964 default:
4965 // This instruction is not vectorized by simple widening.
4966 LLVM_DEBUG(dbgs() << "LV: Found an unhandled instruction: " << I)do { } while (false);
4967 llvm_unreachable("Unhandled instruction!")__builtin_unreachable();
4968 } // end of switch.
4969}
4970
4971void InnerLoopVectorizer::widenCallInstruction(CallInst &I, VPValue *Def,
4972 VPUser &ArgOperands,
4973 VPTransformState &State) {
4974 assert(!isa<DbgInfoIntrinsic>(I) &&((void)0)
4975 "DbgInfoIntrinsic should have been dropped during VPlan construction")((void)0);
4976 setDebugLocFromInst(&I);
4977
4978 Module *M = I.getParent()->getParent()->getParent();
4979 auto *CI = cast<CallInst>(&I);
4980
4981 SmallVector<Type *, 4> Tys;
4982 for (Value *ArgOperand : CI->arg_operands())
4983 Tys.push_back(ToVectorTy(ArgOperand->getType(), VF.getKnownMinValue()));
4984
4985 Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
4986
4987 // The flag shows whether we use Intrinsic or a usual Call for vectorized
4988 // version of the instruction.
4989 // Is it beneficial to perform intrinsic call compared to lib call?
4990 bool NeedToScalarize = false;
4991 InstructionCost CallCost = Cost->getVectorCallCost(CI, VF, NeedToScalarize);
4992 InstructionCost IntrinsicCost = ID ? Cost->getVectorIntrinsicCost(CI, VF) : 0;
4993 bool UseVectorIntrinsic = ID && IntrinsicCost <= CallCost;
4994 assert((UseVectorIntrinsic || !NeedToScalarize) &&((void)0)
4995 "Instruction should be scalarized elsewhere.")((void)0);
4996 assert((IntrinsicCost.isValid() || CallCost.isValid()) &&((void)0)
4997 "Either the intrinsic cost or vector call cost must be valid")((void)0);
4998
4999 for (unsigned Part = 0; Part < UF; ++Part) {
5000 SmallVector<Type *, 2> TysForDecl = {CI->getType()};
5001 SmallVector<Value *, 4> Args;
5002 for (auto &I : enumerate(ArgOperands.operands())) {
5003 // Some intrinsics have a scalar argument - don't replace it with a
5004 // vector.
5005 Value *Arg;
5006 if (!UseVectorIntrinsic || !hasVectorInstrinsicScalarOpd(ID, I.index()))
5007 Arg = State.get(I.value(), Part);
5008 else {
5009 Arg = State.get(I.value(), VPIteration(0, 0));
5010 if (hasVectorInstrinsicOverloadedScalarOpd(ID, I.index()))
5011 TysForDecl.push_back(Arg->getType());
5012 }
5013 Args.push_back(Arg);
5014 }
5015
5016 Function *VectorF;
5017 if (UseVectorIntrinsic) {
5018 // Use vector version of the intrinsic.
5019 if (VF.isVector())
5020 TysForDecl[0] = VectorType::get(CI->getType()->getScalarType(), VF);
5021 VectorF = Intrinsic::getDeclaration(M, ID, TysForDecl);
5022 assert(VectorF && "Can't retrieve vector intrinsic.")((void)0);
5023 } else {
5024 // Use vector version of the function call.
5025 const VFShape Shape = VFShape::get(*CI, VF, false /*HasGlobalPred*/);
5026#ifndef NDEBUG1
5027 assert(VFDatabase(*CI).getVectorizedFunction(Shape) != nullptr &&((void)0)
5028 "Can't create vector function.")((void)0);
5029#endif
5030 VectorF = VFDatabase(*CI).getVectorizedFunction(Shape);
5031 }
5032 SmallVector<OperandBundleDef, 1> OpBundles;
5033 CI->getOperandBundlesAsDefs(OpBundles);
5034 CallInst *V = Builder.CreateCall(VectorF, Args, OpBundles);
5035
5036 if (isa<FPMathOperator>(V))
5037 V->copyFastMathFlags(CI);
5038
5039 State.set(Def, V, Part);
5040 addMetadata(V, &I);
5041 }
5042}
5043
5044void InnerLoopVectorizer::widenSelectInstruction(SelectInst &I, VPValue *VPDef,
5045 VPUser &Operands,
5046 bool InvariantCond,
5047 VPTransformState &State) {
5048 setDebugLocFromInst(&I);
5049
5050 // The condition can be loop invariant but still defined inside the
5051 // loop. This means that we can't just use the original 'cond' value.
5052 // We have to take the 'vectorized' value and pick the first lane.
5053 // Instcombine will make this a no-op.
5054 auto *InvarCond = InvariantCond
5055 ? State.get(Operands.getOperand(0), VPIteration(0, 0))
5056 : nullptr;
5057
5058 for (unsigned Part = 0; Part < UF; ++Part) {
5059 Value *Cond =
5060 InvarCond ? InvarCond : State.get(Operands.getOperand(0), Part);
5061 Value *Op0 = State.get(Operands.getOperand(1), Part);
5062 Value *Op1 = State.get(Operands.getOperand(2), Part);
5063 Value *Sel = Builder.CreateSelect(Cond, Op0, Op1);
5064 State.set(VPDef, Sel, Part);
5065 addMetadata(Sel, &I);
5066 }
5067}
5068
5069void LoopVectorizationCostModel::collectLoopScalars(ElementCount VF) {
5070 // We should not collect Scalars more than once per VF. Right now, this
5071 // function is called from collectUniformsAndScalars(), which already does
5072 // this check. Collecting Scalars for VF=1 does not make any sense.
5073 assert(VF.isVector() && Scalars.find(VF) == Scalars.end() &&((void)0)
5074 "This function should not be visited twice for the same VF")((void)0);
5075
5076 SmallSetVector<Instruction *, 8> Worklist;
5077
5078 // These sets are used to seed the analysis with pointers used by memory
5079 // accesses that will remain scalar.
5080 SmallSetVector<Instruction *, 8> ScalarPtrs;
5081 SmallPtrSet<Instruction *, 8> PossibleNonScalarPtrs;
5082 auto *Latch = TheLoop->getLoopLatch();
5083
5084 // A helper that returns true if the use of Ptr by MemAccess will be scalar.
5085 // The pointer operands of loads and stores will be scalar as long as the
5086 // memory access is not a gather or scatter operation. The value operand of a
5087 // store will remain scalar if the store is scalarized.
5088 auto isScalarUse = [&](Instruction *MemAccess, Value *Ptr) {
5089 InstWidening WideningDecision = getWideningDecision(MemAccess, VF);
5090 assert(WideningDecision != CM_Unknown &&((void)0)
5091 "Widening decision should be ready at this moment")((void)0);
5092 if (auto *Store = dyn_cast<StoreInst>(MemAccess))
5093 if (Ptr == Store->getValueOperand())
5094 return WideningDecision == CM_Scalarize;
5095 assert(Ptr == getLoadStorePointerOperand(MemAccess) &&((void)0)
5096 "Ptr is neither a value or pointer operand")((void)0);
5097 return WideningDecision != CM_GatherScatter;
5098 };
5099
5100 // A helper that returns true if the given value is a bitcast or
5101 // getelementptr instruction contained in the loop.
5102 auto isLoopVaryingBitCastOrGEP = [&](Value *V) {
5103 return ((isa<BitCastInst>(V) && V->getType()->isPointerTy()) ||
5104 isa<GetElementPtrInst>(V)) &&
5105 !TheLoop->isLoopInvariant(V);
5106 };
5107
5108 auto isScalarPtrInduction = [&](Instruction *MemAccess, Value *Ptr) {
5109 if (!isa<PHINode>(Ptr) ||
5110 !Legal->getInductionVars().count(cast<PHINode>(Ptr)))
5111 return false;
5112 auto &Induction = Legal->getInductionVars()[cast<PHINode>(Ptr)];
5113 if (Induction.getKind() != InductionDescriptor::IK_PtrInduction)
5114 return false;
5115 return isScalarUse(MemAccess, Ptr);
5116 };
5117
5118 // A helper that evaluates a memory access's use of a pointer. If the
5119 // pointer is actually the pointer induction of a loop, it is being
5120 // inserted into Worklist. If the use will be a scalar use, and the
5121 // pointer is only used by memory accesses, we place the pointer in
5122 // ScalarPtrs. Otherwise, the pointer is placed in PossibleNonScalarPtrs.
5123 auto evaluatePtrUse = [&](Instruction *MemAccess, Value *Ptr) {
5124 if (isScalarPtrInduction(MemAccess, Ptr)) {
5125 Worklist.insert(cast<Instruction>(Ptr));
5126 LLVM_DEBUG(dbgs() << "LV: Found new scalar instruction: " << *Ptrdo { } while (false)
5127 << "\n")do { } while (false);
5128
5129 Instruction *Update = cast<Instruction>(
5130 cast<PHINode>(Ptr)->getIncomingValueForBlock(Latch));
5131 ScalarPtrs.insert(Update);
5132 return;
5133 }
5134 // We only care about bitcast and getelementptr instructions contained in
5135 // the loop.
5136 if (!isLoopVaryingBitCastOrGEP(Ptr))
5137 return;
5138
5139 // If the pointer has already been identified as scalar (e.g., if it was
5140 // also identified as uniform), there's nothing to do.
5141 auto *I = cast<Instruction>(Ptr);
5142 if (Worklist.count(I))
5143 return;
5144
5145 // If all users of the pointer will be memory accesses and scalar, place the
5146 // pointer in ScalarPtrs. Otherwise, place the pointer in
5147 // PossibleNonScalarPtrs.
5148 if (llvm::all_of(I->users(), [&](User *U) {
5149 return (isa<LoadInst>(U) || isa<StoreInst>(U)) &&
5150 isScalarUse(cast<Instruction>(U), Ptr);
5151 }))
5152 ScalarPtrs.insert(I);
5153 else
5154 PossibleNonScalarPtrs.insert(I);
5155 };
5156
5157 // We seed the scalars analysis with three classes of instructions: (1)
5158 // instructions marked uniform-after-vectorization and (2) bitcast,
5159 // getelementptr and (pointer) phi instructions used by memory accesses
5160 // requiring a scalar use.
5161 //
5162 // (1) Add to the worklist all instructions that have been identified as
5163 // uniform-after-vectorization.
5164 Worklist.insert(Uniforms[VF].begin(), Uniforms[VF].end());
5165
5166 // (2) Add to the worklist all bitcast and getelementptr instructions used by
5167 // memory accesses requiring a scalar use. The pointer operands of loads and
5168 // stores will be scalar as long as the memory accesses is not a gather or
5169 // scatter operation. The value operand of a store will remain scalar if the
5170 // store is scalarized.
5171 for (auto *BB : TheLoop->blocks())
5172 for (auto &I : *BB) {
5173 if (auto *Load = dyn_cast<LoadInst>(&I)) {
5174 evaluatePtrUse(Load, Load->getPointerOperand());
5175 } else if (auto *Store = dyn_cast<StoreInst>(&I)) {
5176 evaluatePtrUse(Store, Store->getPointerOperand());
5177 evaluatePtrUse(Store, Store->getValueOperand());
5178 }
5179 }
5180 for (auto *I : ScalarPtrs)
5181 if (!PossibleNonScalarPtrs.count(I)) {
5182 LLVM_DEBUG(dbgs() << "LV: Found scalar instruction: " << *I << "\n")do { } while (false);
5183 Worklist.insert(I);
5184 }
5185
5186 // Insert the forced scalars.
5187 // FIXME: Currently widenPHIInstruction() often creates a dead vector
5188 // induction variable when the PHI user is scalarized.
5189 auto ForcedScalar = ForcedScalars.find(VF);
5190 if (ForcedScalar != ForcedScalars.end())
5191 for (auto *I : ForcedScalar->second)
5192 Worklist.insert(I);
5193
5194 // Expand the worklist by looking through any bitcasts and getelementptr
5195 // instructions we've already identified as scalar. This is similar to the
5196 // expansion step in collectLoopUniforms(); however, here we're only
5197 // expanding to include additional bitcasts and getelementptr instructions.
5198 unsigned Idx = 0;
5199 while (Idx != Worklist.size()) {
5200 Instruction *Dst = Worklist[Idx++];
5201 if (!isLoopVaryingBitCastOrGEP(Dst->getOperand(0)))
5202 continue;
5203 auto *Src = cast<Instruction>(Dst->getOperand(0));
5204 if (llvm::all_of(Src->users(), [&](User *U) -> bool {
5205 auto *J = cast<Instruction>(U);
5206 return !TheLoop->contains(J) || Worklist.count(J) ||
5207 ((isa<LoadInst>(J) || isa<StoreInst>(J)) &&
5208 isScalarUse(J, Src));
5209 })) {
5210 Worklist.insert(Src);
5211 LLVM_DEBUG(dbgs() << "LV: Found scalar instruction: " << *Src << "\n")do { } while (false);
5212 }
5213 }
5214
5215 // An induction variable will remain scalar if all users of the induction
5216 // variable and induction variable update remain scalar.
5217 for (auto &Induction : Legal->getInductionVars()) {
5218 auto *Ind = Induction.first;
5219 auto *IndUpdate = cast<Instruction>(Ind->getIncomingValueForBlock(Latch));
5220
5221 // If tail-folding is applied, the primary induction variable will be used
5222 // to feed a vector compare.
5223 if (Ind == Legal->getPrimaryInduction() && foldTailByMasking())
5224 continue;
5225
5226 // Determine if all users of the induction variable are scalar after
5227 // vectorization.
5228 auto ScalarInd = llvm::all_of(Ind->users(), [&](User *U) -> bool {
5229 auto *I = cast<Instruction>(U);
5230 return I == IndUpdate || !TheLoop->contains(I) || Worklist.count(I);
5231 });
5232 if (!ScalarInd)
5233 continue;
5234
5235 // Determine if all users of the induction variable update instruction are
5236 // scalar after vectorization.
5237 auto ScalarIndUpdate =
5238 llvm::all_of(IndUpdate->users(), [&](User *U) -> bool {
5239 auto *I = cast<Instruction>(U);
5240 return I == Ind || !TheLoop->contains(I) || Worklist.count(I);
5241 });
5242 if (!ScalarIndUpdate)
5243 continue;
5244
5245 // The induction variable and its update instruction will remain scalar.
5246 Worklist.insert(Ind);
5247 Worklist.insert(IndUpdate);
5248 LLVM_DEBUG(dbgs() << "LV: Found scalar instruction: " << *Ind << "\n")do { } while (false);
5249 LLVM_DEBUG(dbgs() << "LV: Found scalar instruction: " << *IndUpdatedo { } while (false)
5250 << "\n")do { } while (false);
5251 }
5252
5253 Scalars[VF].insert(Worklist.begin(), Worklist.end());
5254}
5255
5256bool LoopVectorizationCostModel::isScalarWithPredication(Instruction *I) const {
5257 if (!blockNeedsPredication(I->getParent()))
5258 return false;
5259 switch(I->getOpcode()) {
5260 default:
5261 break;
5262 case Instruction::Load:
5263 case Instruction::Store: {
5264 if (!Legal->isMaskRequired(I))
5265 return false;
5266 auto *Ptr = getLoadStorePointerOperand(I);
5267 auto *Ty = getLoadStoreType(I);
5268 const Align Alignment = getLoadStoreAlignment(I);
5269 return isa<LoadInst>(I) ? !(isLegalMaskedLoad(Ty, Ptr, Alignment) ||
5270 TTI.isLegalMaskedGather(Ty, Alignment))
5271 : !(isLegalMaskedStore(Ty, Ptr, Alignment) ||
5272 TTI.isLegalMaskedScatter(Ty, Alignment));
5273 }
5274 case Instruction::UDiv:
5275 case Instruction::SDiv:
5276 case Instruction::SRem:
5277 case Instruction::URem:
5278 return mayDivideByZero(*I);
5279 }
5280 return false;
5281}
5282
5283bool LoopVectorizationCostModel::interleavedAccessCanBeWidened(
5284 Instruction *I, ElementCount VF) {
5285 assert(isAccessInterleaved(I) && "Expecting interleaved access.")((void)0);
5286 assert(getWideningDecision(I, VF) == CM_Unknown &&((void)0)
5287 "Decision should not be set yet.")((void)0);
5288 auto *Group = getInterleavedAccessGroup(I);
5289 assert(Group && "Must have a group.")((void)0);
5290
5291 // If the instruction's allocated size doesn't equal it's type size, it
5292 // requires padding and will be scalarized.
5293 auto &DL = I->getModule()->getDataLayout();
5294 auto *ScalarTy = getLoadStoreType(I);
5295 if (hasIrregularType(ScalarTy, DL))
5296 return false;
5297
5298 // Check if masking is required.
5299 // A Group may need masking for one of two reasons: it resides in a block that
5300 // needs predication, or it was decided to use masking to deal with gaps.
5301 bool PredicatedAccessRequiresMasking =
5302 Legal->blockNeedsPredication(I->getParent()) && Legal->isMaskRequired(I);
5303 bool AccessWithGapsRequiresMasking =
5304 Group->requiresScalarEpilogue() && !isScalarEpilogueAllowed();
5305 if (!PredicatedAccessRequiresMasking && !AccessWithGapsRequiresMasking)
5306 return true;
5307
5308 // If masked interleaving is required, we expect that the user/target had
5309 // enabled it, because otherwise it either wouldn't have been created or
5310 // it should have been invalidated by the CostModel.
5311 assert(useMaskedInterleavedAccesses(TTI) &&((void)0)
5312 "Masked interleave-groups for predicated accesses are not enabled.")((void)0);
5313
5314 auto *Ty = getLoadStoreType(I);
5315 const Align Alignment = getLoadStoreAlignment(I);
5316 return isa<LoadInst>(I) ? TTI.isLegalMaskedLoad(Ty, Alignment)
5317 : TTI.isLegalMaskedStore(Ty, Alignment);
5318}
5319
5320bool LoopVectorizationCostModel::memoryInstructionCanBeWidened(
5321 Instruction *I, ElementCount VF) {
5322 // Get and ensure we have a valid memory instruction.
5323 LoadInst *LI = dyn_cast<LoadInst>(I);
5324 StoreInst *SI = dyn_cast<StoreInst>(I);
5325 assert((LI || SI) && "Invalid memory instruction")((void)0);
5326
5327 auto *Ptr = getLoadStorePointerOperand(I);
5328
5329 // In order to be widened, the pointer should be consecutive, first of all.
5330 if (!Legal->isConsecutivePtr(Ptr))
5331 return false;
5332
5333 // If the instruction is a store located in a predicated block, it will be
5334 // scalarized.
5335 if (isScalarWithPredication(I))
5336 return false;
5337
5338 // If the instruction's allocated size doesn't equal it's type size, it
5339 // requires padding and will be scalarized.
5340 auto &DL = I->getModule()->getDataLayout();
5341 auto *ScalarTy = LI ? LI->getType() : SI->getValueOperand()->getType();
5342 if (hasIrregularType(ScalarTy, DL))
5343 return false;
5344
5345 return true;
5346}
5347
5348void LoopVectorizationCostModel::collectLoopUniforms(ElementCount VF) {
5349 // We should not collect Uniforms more than once per VF. Right now,
5350 // this function is called from collectUniformsAndScalars(), which
5351 // already does this check. Collecting Uniforms for VF=1 does not make any
5352 // sense.
5353
5354 assert(VF.isVector() && Uniforms.find(VF) == Uniforms.end() &&((void)0)
5355 "This function should not be visited twice for the same VF")((void)0);
5356
5357 // Visit the list of Uniforms. If we'll not find any uniform value, we'll
5358 // not analyze again. Uniforms.count(VF) will return 1.
5359 Uniforms[VF].clear();
5360
5361 // We now know that the loop is vectorizable!
5362 // Collect instructions inside the loop that will remain uniform after
5363 // vectorization.
5364
5365 // Global values, params and instructions outside of current loop are out of
5366 // scope.
5367 auto isOutOfScope = [&](Value *V) -> bool {
5368 Instruction *I = dyn_cast<Instruction>(V);
5369 return (!I || !TheLoop->contains(I));
5370 };
5371
5372 SetVector<Instruction *> Worklist;
5373 BasicBlock *Latch = TheLoop->getLoopLatch();
5374
5375 // Instructions that are scalar with predication must not be considered
5376 // uniform after vectorization, because that would create an erroneous
5377 // replicating region where only a single instance out of VF should be formed.
5378 // TODO: optimize such seldom cases if found important, see PR40816.
5379 auto addToWorklistIfAllowed = [&](Instruction *I) -> void {
5380 if (isOutOfScope(I)) {
5381 LLVM_DEBUG(dbgs() << "LV: Found not uniform due to scope: "do { } while (false)
5382 << *I << "\n")do { } while (false);
5383 return;
5384 }
5385 if (isScalarWithPredication(I)) {
5386 LLVM_DEBUG(dbgs() << "LV: Found not uniform being ScalarWithPredication: "do { } while (false)
5387 << *I << "\n")do { } while (false);
5388 return;
5389 }
5390 LLVM_DEBUG(dbgs() << "LV: Found uniform instruction: " << *I << "\n")do { } while (false);
5391 Worklist.insert(I);
5392 };
5393
5394 // Start with the conditional branch. If the branch condition is an
5395 // instruction contained in the loop that is only used by the branch, it is
5396 // uniform.
5397 auto *Cmp = dyn_cast<Instruction>(Latch->getTerminator()->getOperand(0));
5398 if (Cmp && TheLoop->contains(Cmp) && Cmp->hasOneUse())
5399 addToWorklistIfAllowed(Cmp);
5400
5401 auto isUniformDecision = [&](Instruction *I, ElementCount VF) {
5402 InstWidening WideningDecision = getWideningDecision(I, VF);
5403 assert(WideningDecision != CM_Unknown &&((void)0)
5404 "Widening decision should be ready at this moment")((void)0);
5405
5406 // A uniform memory op is itself uniform. We exclude uniform stores
5407 // here as they demand the last lane, not the first one.
5408 if (isa<LoadInst>(I) && Legal->isUniformMemOp(*I)) {
5409 assert(WideningDecision == CM_Scalarize)((void)0);
5410 return true;
5411 }
5412
5413 return (WideningDecision == CM_Widen ||
5414 WideningDecision == CM_Widen_Reverse ||
5415 WideningDecision == CM_Interleave);
5416 };
5417
5418
5419 // Returns true if Ptr is the pointer operand of a memory access instruction
5420 // I, and I is known to not require scalarization.
5421 auto isVectorizedMemAccessUse = [&](Instruction *I, Value *Ptr) -> bool {
5422 return getLoadStorePointerOperand(I) == Ptr && isUniformDecision(I, VF);
5423 };
5424
5425 // Holds a list of values which are known to have at least one uniform use.
5426 // Note that there may be other uses which aren't uniform. A "uniform use"
5427 // here is something which only demands lane 0 of the unrolled iterations;
5428 // it does not imply that all lanes produce the same value (e.g. this is not
5429 // the usual meaning of uniform)
5430 SetVector<Value *> HasUniformUse;
5431
5432 // Scan the loop for instructions which are either a) known to have only
5433 // lane 0 demanded or b) are uses which demand only lane 0 of their operand.
5434 for (auto *BB : TheLoop->blocks())
5435 for (auto &I : *BB) {
5436 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I)) {
5437 switch (II->getIntrinsicID()) {
5438 case Intrinsic::sideeffect:
5439 case Intrinsic::experimental_noalias_scope_decl:
5440 case Intrinsic::assume:
5441 case Intrinsic::lifetime_start:
5442 case Intrinsic::lifetime_end:
5443 if (TheLoop->hasLoopInvariantOperands(&I))
5444 addToWorklistIfAllowed(&I);
5445 break;
5446 default:
5447 break;
5448 }
5449 }
5450
5451 // If there's no pointer operand, there's nothing to do.
5452 auto *Ptr = getLoadStorePointerOperand(&I);
5453 if (!Ptr)
5454 continue;
5455
5456 // A uniform memory op is itself uniform. We exclude uniform stores
5457 // here as they demand the last lane, not the first one.
5458 if (isa<LoadInst>(I) && Legal->isUniformMemOp(I))
5459 addToWorklistIfAllowed(&I);
5460
5461 if (isUniformDecision(&I, VF)) {
5462 assert(isVectorizedMemAccessUse(&I, Ptr) && "consistency check")((void)0);
5463 HasUniformUse.insert(Ptr);
5464 }
5465 }
5466
5467 // Add to the worklist any operands which have *only* uniform (e.g. lane 0
5468 // demanding) users. Since loops are assumed to be in LCSSA form, this
5469 // disallows uses outside the loop as well.
5470 for (auto *V : HasUniformUse) {
5471 if (isOutOfScope(V))
5472 continue;
5473 auto *I = cast<Instruction>(V);
5474 auto UsersAreMemAccesses =
5475 llvm::all_of(I->users(), [&](User *U) -> bool {
5476 return isVectorizedMemAccessUse(cast<Instruction>(U), V);
5477 });
5478 if (UsersAreMemAccesses)
5479 addToWorklistIfAllowed(I);
5480 }
5481
5482 // Expand Worklist in topological order: whenever a new instruction
5483 // is added , its users should be already inside Worklist. It ensures
5484 // a uniform instruction will only be used by uniform instructions.
5485 unsigned idx = 0;
5486 while (idx != Worklist.size()) {
5487 Instruction *I = Worklist[idx++];
5488
5489 for (auto OV : I->operand_values()) {
5490 // isOutOfScope operands cannot be uniform instructions.
5491 if (isOutOfScope(OV))
5492 continue;
5493 // First order recurrence Phi's should typically be considered
5494 // non-uniform.
5495 auto *OP = dyn_cast<PHINode>(OV);
5496 if (OP && Legal->isFirstOrderRecurrence(OP))
5497 continue;
5498 // If all the users of the operand are uniform, then add the
5499 // operand into the uniform worklist.
5500 auto *OI = cast<Instruction>(OV);
5501 if (llvm::all_of(OI->users(), [&](User *U) -> bool {
5502 auto *J = cast<Instruction>(U);
5503 return Worklist.count(J) || isVectorizedMemAccessUse(J, OI);
5504 }))
5505 addToWorklistIfAllowed(OI);
5506 }
5507 }
5508
5509 // For an instruction to be added into Worklist above, all its users inside
5510 // the loop should also be in Worklist. However, this condition cannot be
5511 // true for phi nodes that form a cyclic dependence. We must process phi
5512 // nodes separately. An induction variable will remain uniform if all users
5513 // of the induction variable and induction variable update remain uniform.
5514 // The code below handles both pointer and non-pointer induction variables.
5515 for (auto &Induction : Legal->getInductionVars()) {
5516 auto *Ind = Induction.first;
5517 auto *IndUpdate = cast<Instruction>(Ind->getIncomingValueForBlock(Latch));
5518
5519 // Determine if all users of the induction variable are uniform after
5520 // vectorization.
5521 auto UniformInd = llvm::all_of(Ind->users(), [&](User *U) -> bool {
5522 auto *I = cast<Instruction>(U);
5523 return I == IndUpdate || !TheLoop->contains(I) || Worklist.count(I) ||
5524 isVectorizedMemAccessUse(I, Ind);
5525 });
5526 if (!UniformInd)
5527 continue;
5528
5529 // Determine if all users of the induction variable update instruction are
5530 // uniform after vectorization.
5531 auto UniformIndUpdate =
5532 llvm::all_of(IndUpdate->users(), [&](User *U) -> bool {
5533 auto *I = cast<Instruction>(U);
5534 return I == Ind || !TheLoop->contains(I) || Worklist.count(I) ||
5535 isVectorizedMemAccessUse(I, IndUpdate);
5536 });
5537 if (!UniformIndUpdate)
5538 continue;
5539
5540 // The induction variable and its update instruction will remain uniform.
5541 addToWorklistIfAllowed(Ind);
5542 addToWorklistIfAllowed(IndUpdate);
5543 }
5544
5545 Uniforms[VF].insert(Worklist.begin(), Worklist.end());
5546}
5547
5548bool LoopVectorizationCostModel::runtimeChecksRequired() {
5549 LLVM_DEBUG(dbgs() << "LV: Performing code size checks.\n")do { } while (false);
5550
5551 if (Legal->getRuntimePointerChecking()->Need) {
5552 reportVectorizationFailure("Runtime ptr check is required with -Os/-Oz",
5553 "runtime pointer checks needed. Enable vectorization of this "
5554 "loop with '#pragma clang loop vectorize(enable)' when "
5555 "compiling with -Os/-Oz",
5556 "CantVersionLoopWithOptForSize", ORE, TheLoop);
5557 return true;
5558 }
5559
5560 if (!PSE.getUnionPredicate().getPredicates().empty()) {
5561 reportVectorizationFailure("Runtime SCEV check is required with -Os/-Oz",
5562 "runtime SCEV checks needed. Enable vectorization of this "
5563 "loop with '#pragma clang loop vectorize(enable)' when "
5564 "compiling with -Os/-Oz",
5565 "CantVersionLoopWithOptForSize", ORE, TheLoop);
5566 return true;
5567 }
5568
5569 // FIXME: Avoid specializing for stride==1 instead of bailing out.
5570 if (!Legal->getLAI()->getSymbolicStrides().empty()) {
5571 reportVectorizationFailure("Runtime stride check for small trip count",
5572 "runtime stride == 1 checks needed. Enable vectorization of "
5573 "this loop without such check by compiling with -Os/-Oz",
5574 "CantVersionLoopWithOptForSize", ORE, TheLoop);
5575 return true;
5576 }
5577
5578 return false;
5579}
5580
5581ElementCount
5582LoopVectorizationCostModel::getMaxLegalScalableVF(unsigned MaxSafeElements) {
5583 if (!TTI.supportsScalableVectors() && !ForceTargetSupportsScalableVectors) {
5584 reportVectorizationInfo(
5585 "Disabling scalable vectorization, because target does not "
5586 "support scalable vectors.",
5587 "ScalableVectorsUnsupported", ORE, TheLoop);
5588 return ElementCount::getScalable(0);
5589 }
5590
5591 if (Hints->isScalableVectorizationDisabled()) {
5592 reportVectorizationInfo("Scalable vectorization is explicitly disabled",
5593 "ScalableVectorizationDisabled", ORE, TheLoop);
5594 return ElementCount::getScalable(0);
5595 }
5596
5597 auto MaxScalableVF = ElementCount::getScalable(
5598 std::numeric_limits<ElementCount::ScalarTy>::max());
5599
5600 // Test that the loop-vectorizer can legalize all operations for this MaxVF.
5601 // FIXME: While for scalable vectors this is currently sufficient, this should
5602 // be replaced by a more detailed mechanism that filters out specific VFs,
5603 // instead of invalidating vectorization for a whole set of VFs based on the
5604 // MaxVF.
5605
5606 // Disable scalable vectorization if the loop contains unsupported reductions.
5607 if (!canVectorizeReductions(MaxScalableVF)) {
5608 reportVectorizationInfo(
5609 "Scalable vectorization not supported for the reduction "
5610 "operations found in this loop.",
5611 "ScalableVFUnfeasible", ORE, TheLoop);
5612 return ElementCount::getScalable(0);
5613 }
5614
5615 // Disable scalable vectorization if the loop contains any instructions
5616 // with element types not supported for scalable vectors.
5617 if (any_of(ElementTypesInLoop, [&](Type *Ty) {
5618 return !Ty->isVoidTy() &&
5619 !this->TTI.isElementTypeLegalForScalableVector(Ty);
5620 })) {
5621 reportVectorizationInfo("Scalable vectorization is not supported "
5622 "for all element types found in this loop.",
5623 "ScalableVFUnfeasible", ORE, TheLoop);
5624 return ElementCount::getScalable(0);
5625 }
5626
5627 if (Legal->isSafeForAnyVectorWidth())
5628 return MaxScalableVF;
5629
5630 // Limit MaxScalableVF by the maximum safe dependence distance.
5631 Optional<unsigned> MaxVScale = TTI.getMaxVScale();
5632 MaxScalableVF = ElementCount::getScalable(
5633 MaxVScale ? (MaxSafeElements / MaxVScale.getValue()) : 0);
5634 if (!MaxScalableVF)
5635 reportVectorizationInfo(
5636 "Max legal vector width too small, scalable vectorization "
5637 "unfeasible.",
5638 "ScalableVFUnfeasible", ORE, TheLoop);
5639
5640 return MaxScalableVF;
5641}
5642
5643FixedScalableVFPair
5644LoopVectorizationCostModel::computeFeasibleMaxVF(unsigned ConstTripCount,
5645 ElementCount UserVF) {
5646 MinBWs = computeMinimumValueSizes(TheLoop->getBlocks(), *DB, &TTI);
5647 unsigned SmallestType, WidestType;
5648 std::tie(SmallestType, WidestType) = getSmallestAndWidestTypes();
5649
5650 // Get the maximum safe dependence distance in bits computed by LAA.
5651 // It is computed by MaxVF * sizeOf(type) * 8, where type is taken from
5652 // the memory accesses that is most restrictive (involved in the smallest
5653 // dependence distance).
5654 unsigned MaxSafeElements =
5655 PowerOf2Floor(Legal->getMaxSafeVectorWidthInBits() / WidestType);
5656
5657 auto MaxSafeFixedVF = ElementCount::getFixed(MaxSafeElements);
5658 auto MaxSafeScalableVF = getMaxLegalScalableVF(MaxSafeElements);
5659
5660 LLVM_DEBUG(dbgs() << "LV: The max safe fixed VF is: " << MaxSafeFixedVFdo { } while (false)
5661 << ".\n")do { } while (false);
5662 LLVM_DEBUG(dbgs() << "LV: The max safe scalable VF is: " << MaxSafeScalableVFdo { } while (false)
5663 << ".\n")do { } while (false);
5664
5665 // First analyze the UserVF, fall back if the UserVF should be ignored.
5666 if (UserVF) {
5667 auto MaxSafeUserVF =
5668 UserVF.isScalable() ? MaxSafeScalableVF : MaxSafeFixedVF;
5669
5670 if (ElementCount::isKnownLE(UserVF, MaxSafeUserVF)) {
5671 // If `VF=vscale x N` is safe, then so is `VF=N`
5672 if (UserVF.isScalable())
5673 return FixedScalableVFPair(
5674 ElementCount::getFixed(UserVF.getKnownMinValue()), UserVF);
5675 else
5676 return UserVF;
5677 }
5678
5679 assert(ElementCount::isKnownGT(UserVF, MaxSafeUserVF))((void)0);
5680
5681 // Only clamp if the UserVF is not scalable. If the UserVF is scalable, it
5682 // is better to ignore the hint and let the compiler choose a suitable VF.
5683 if (!UserVF.isScalable()) {
5684 LLVM_DEBUG(dbgs() << "LV: User VF=" << UserVFdo { } while (false)
5685 << " is unsafe, clamping to max safe VF="do { } while (false)
5686 << MaxSafeFixedVF << ".\n")do { } while (false);
5687 ORE->emit([&]() {
5688 return OptimizationRemarkAnalysis(DEBUG_TYPE"loop-vectorize", "VectorizationFactor",
5689 TheLoop->getStartLoc(),
5690 TheLoop->getHeader())
5691 << "User-specified vectorization factor "
5692 << ore::NV("UserVectorizationFactor", UserVF)
5693 << " is unsafe, clamping to maximum safe vectorization factor "
5694 << ore::NV("VectorizationFactor", MaxSafeFixedVF);
5695 });
5696 return MaxSafeFixedVF;
5697 }
5698
5699 LLVM_DEBUG(dbgs() << "LV: User VF=" << UserVFdo { } while (false)
5700 << " is unsafe. Ignoring scalable UserVF.\n")do { } while (false);
5701 ORE->emit([&]() {
5702 return OptimizationRemarkAnalysis(DEBUG_TYPE"loop-vectorize", "VectorizationFactor",
5703 TheLoop->getStartLoc(),
5704 TheLoop->getHeader())
5705 << "User-specified vectorization factor "
5706 << ore::NV("UserVectorizationFactor", UserVF)
5707 << " is unsafe. Ignoring the hint to let the compiler pick a "
5708 "suitable VF.";
5709 });
5710 }
5711
5712 LLVM_DEBUG(dbgs() << "LV: The Smallest and Widest types: " << SmallestTypedo { } while (false)
5713 << " / " << WidestType << " bits.\n")do { } while (false);
5714
5715 FixedScalableVFPair Result(ElementCount::getFixed(1),
5716 ElementCount::getScalable(0));
5717 if (auto MaxVF = getMaximizedVFForTarget(ConstTripCount, SmallestType,
5718 WidestType, MaxSafeFixedVF))
5719 Result.FixedVF = MaxVF;
5720
5721 if (auto MaxVF = getMaximizedVFForTarget(ConstTripCount, SmallestType,
5722 WidestType, MaxSafeScalableVF))
5723 if (MaxVF.isScalable()) {
5724 Result.ScalableVF = MaxVF;
5725 LLVM_DEBUG(dbgs() << "LV: Found feasible scalable VF = " << MaxVFdo { } while (false)
5726 << "\n")do { } while (false);
5727 }
5728
5729 return Result;
5730}
5731
5732FixedScalableVFPair
5733LoopVectorizationCostModel::computeMaxVF(ElementCount UserVF, unsigned UserIC) {
5734 if (Legal->getRuntimePointerChecking()->Need && TTI.hasBranchDivergence()) {
5735 // TODO: It may by useful to do since it's still likely to be dynamically
5736 // uniform if the target can skip.
5737 reportVectorizationFailure(
5738 "Not inserting runtime ptr check for divergent target",
5739 "runtime pointer checks needed. Not enabled for divergent target",
5740 "CantVersionLoopWithDivergentTarget", ORE, TheLoop);
5741 return FixedScalableVFPair::getNone();
5742 }
5743
5744 unsigned TC = PSE.getSE()->getSmallConstantTripCount(TheLoop);
5745 LLVM_DEBUG(dbgs() << "LV: Found trip count: " << TC << '\n')do { } while (false);
5746 if (TC == 1) {
5747 reportVectorizationFailure("Single iteration (non) loop",
5748 "loop trip count is one, irrelevant for vectorization",
5749 "SingleIterationLoop", ORE, TheLoop);
5750 return FixedScalableVFPair::getNone();
5751 }
5752
5753 switch (ScalarEpilogueStatus) {
5754 case CM_ScalarEpilogueAllowed:
5755 return computeFeasibleMaxVF(TC, UserVF);
5756 case CM_ScalarEpilogueNotAllowedUsePredicate:
5757 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5758 case CM_ScalarEpilogueNotNeededUsePredicate:
5759 LLVM_DEBUG(do { } while (false)
5760 dbgs() << "LV: vector predicate hint/switch found.\n"do { } while (false)
5761 << "LV: Not allowing scalar epilogue, creating predicated "do { } while (false)
5762 << "vector loop.\n")do { } while (false);
5763 break;
5764 case CM_ScalarEpilogueNotAllowedLowTripLoop:
5765 // fallthrough as a special case of OptForSize
5766 case CM_ScalarEpilogueNotAllowedOptSize:
5767 if (ScalarEpilogueStatus == CM_ScalarEpilogueNotAllowedOptSize)
5768 LLVM_DEBUG(do { } while (false)
5769 dbgs() << "LV: Not allowing scalar epilogue due to -Os/-Oz.\n")do { } while (false);
5770 else
5771 LLVM_DEBUG(dbgs() << "LV: Not allowing scalar epilogue due to low trip "do { } while (false)
5772 << "count.\n")do { } while (false);
5773
5774 // Bail if runtime checks are required, which are not good when optimising
5775 // for size.
5776 if (runtimeChecksRequired())
5777 return FixedScalableVFPair::getNone();
5778
5779 break;
5780 }
5781
5782 // The only loops we can vectorize without a scalar epilogue, are loops with
5783 // a bottom-test and a single exiting block. We'd have to handle the fact
5784 // that not every instruction executes on the last iteration. This will
5785 // require a lane mask which varies through the vector loop body. (TODO)
5786 if (TheLoop->getExitingBlock() != TheLoop->getLoopLatch()) {
5787 // If there was a tail-folding hint/switch, but we can't fold the tail by
5788 // masking, fallback to a vectorization with a scalar epilogue.
5789 if (ScalarEpilogueStatus == CM_ScalarEpilogueNotNeededUsePredicate) {
5790 LLVM_DEBUG(dbgs() << "LV: Cannot fold tail by masking: vectorize with a "do { } while (false)
5791 "scalar epilogue instead.\n")do { } while (false);
5792 ScalarEpilogueStatus = CM_ScalarEpilogueAllowed;
5793 return computeFeasibleMaxVF(TC, UserVF);
5794 }
5795 return FixedScalableVFPair::getNone();
5796 }
5797
5798 // Now try the tail folding
5799
5800 // Invalidate interleave groups that require an epilogue if we can't mask
5801 // the interleave-group.
5802 if (!useMaskedInterleavedAccesses(TTI)) {
5803 assert(WideningDecisions.empty() && Uniforms.empty() && Scalars.empty() &&((void)0)
5804 "No decisions should have been taken at this point")((void)0);
5805 // Note: There is no need to invalidate any cost modeling decisions here, as
5806 // non where taken so far.
5807 InterleaveInfo.invalidateGroupsRequiringScalarEpilogue();
5808 }
5809
5810 FixedScalableVFPair MaxFactors = computeFeasibleMaxVF(TC, UserVF);
5811 // Avoid tail folding if the trip count is known to be a multiple of any VF
5812 // we chose.
5813 // FIXME: The condition below pessimises the case for fixed-width vectors,
5814 // when scalable VFs are also candidates for vectorization.
5815 if (MaxFactors.FixedVF.isVector() && !MaxFactors.ScalableVF) {
5816 ElementCount MaxFixedVF = MaxFactors.FixedVF;
5817 assert((UserVF.isNonZero() || isPowerOf2_32(MaxFixedVF.getFixedValue())) &&((void)0)
5818 "MaxFixedVF must be a power of 2")((void)0);
5819 unsigned MaxVFtimesIC = UserIC ? MaxFixedVF.getFixedValue() * UserIC
5820 : MaxFixedVF.getFixedValue();
5821 ScalarEvolution *SE = PSE.getSE();
5822 const SCEV *BackedgeTakenCount = PSE.getBackedgeTakenCount();
5823 const SCEV *ExitCount = SE->getAddExpr(
5824 BackedgeTakenCount, SE->getOne(BackedgeTakenCount->getType()));
5825 const SCEV *Rem = SE->getURemExpr(
5826 SE->applyLoopGuards(ExitCount, TheLoop),
5827 SE->getConstant(BackedgeTakenCount->getType(), MaxVFtimesIC));
5828 if (Rem->isZero()) {
5829 // Accept MaxFixedVF if we do not have a tail.
5830 LLVM_DEBUG(dbgs() << "LV: No tail will remain for any chosen VF.\n")do { } while (false);
5831 return MaxFactors;
5832 }
5833 }
5834
5835 // For scalable vectors, don't use tail folding as this is currently not yet
5836 // supported. The code is likely to have ended up here if the tripcount is
5837 // low, in which case it makes sense not to use scalable vectors.
5838 if (MaxFactors.ScalableVF.isVector())
5839 MaxFactors.ScalableVF = ElementCount::getScalable(0);
5840
5841 // If we don't know the precise trip count, or if the trip count that we
5842 // found modulo the vectorization factor is not zero, try to fold the tail
5843 // by masking.
5844 // FIXME: look for a smaller MaxVF that does divide TC rather than masking.
5845 if (Legal->prepareToFoldTailByMasking()) {
5846 FoldTailByMasking = true;
5847 return MaxFactors;
5848 }
5849
5850 // If there was a tail-folding hint/switch, but we can't fold the tail by
5851 // masking, fallback to a vectorization with a scalar epilogue.
5852 if (ScalarEpilogueStatus == CM_ScalarEpilogueNotNeededUsePredicate) {
5853 LLVM_DEBUG(dbgs() << "LV: Cannot fold tail by masking: vectorize with a "do { } while (false)
5854 "scalar epilogue instead.\n")do { } while (false);
5855 ScalarEpilogueStatus = CM_ScalarEpilogueAllowed;
5856 return MaxFactors;
5857 }
5858
5859 if (ScalarEpilogueStatus == CM_ScalarEpilogueNotAllowedUsePredicate) {
5860 LLVM_DEBUG(dbgs() << "LV: Can't fold tail by masking: don't vectorize\n")do { } while (false);
5861 return FixedScalableVFPair::getNone();
5862 }
5863
5864 if (TC == 0) {
5865 reportVectorizationFailure(
5866 "Unable to calculate the loop count due to complex control flow",
5867 "unable to calculate the loop count due to complex control flow",
5868 "UnknownLoopCountComplexCFG", ORE, TheLoop);
5869 return FixedScalableVFPair::getNone();
5870 }
5871
5872 reportVectorizationFailure(
5873 "Cannot optimize for size and vectorize at the same time.",
5874 "cannot optimize for size and vectorize at the same time. "
5875 "Enable vectorization of this loop with '#pragma clang loop "
5876 "vectorize(enable)' when compiling with -Os/-Oz",
5877 "NoTailLoopWithOptForSize", ORE, TheLoop);
5878 return FixedScalableVFPair::getNone();
5879}
5880
5881ElementCount LoopVectorizationCostModel::getMaximizedVFForTarget(
5882 unsigned ConstTripCount, unsigned SmallestType, unsigned WidestType,
5883 const ElementCount &MaxSafeVF) {
5884 bool ComputeScalableMaxVF = MaxSafeVF.isScalable();
5885 TypeSize WidestRegister = TTI.getRegisterBitWidth(
5886 ComputeScalableMaxVF ? TargetTransformInfo::RGK_ScalableVector
5887 : TargetTransformInfo::RGK_FixedWidthVector);
5888
5889 // Convenience function to return the minimum of two ElementCounts.
5890 auto MinVF = [](const ElementCount &LHS, const ElementCount &RHS) {
5891 assert((LHS.isScalable() == RHS.isScalable()) &&((void)0)
5892 "Scalable flags must match")((void)0);
5893 return ElementCount::isKnownLT(LHS, RHS) ? LHS : RHS;
5894 };
5895
5896 // Ensure MaxVF is a power of 2; the dependence distance bound may not be.
5897 // Note that both WidestRegister and WidestType may not be a powers of 2.
5898 auto MaxVectorElementCount = ElementCount::get(
5899 PowerOf2Floor(WidestRegister.getKnownMinSize() / WidestType),
5900 ComputeScalableMaxVF);
5901 MaxVectorElementCount = MinVF(MaxVectorElementCount, MaxSafeVF);
5902 LLVM_DEBUG(dbgs() << "LV: The Widest register safe to use is: "do { } while (false)
5903 << (MaxVectorElementCount * WidestType) << " bits.\n")do { } while (false);
5904
5905 if (!MaxVectorElementCount) {
5906 LLVM_DEBUG(dbgs() << "LV: The target has no "do { } while (false)
5907 << (ComputeScalableMaxVF ? "scalable" : "fixed")do { } while (false)
5908 << " vector registers.\n")do { } while (false);
5909 return ElementCount::getFixed(1);
5910 }
5911
5912 const auto TripCountEC = ElementCount::getFixed(ConstTripCount);
5913 if (ConstTripCount &&
5914 ElementCount::isKnownLE(TripCountEC, MaxVectorElementCount) &&
5915 isPowerOf2_32(ConstTripCount)) {
5916 // We need to clamp the VF to be the ConstTripCount. There is no point in
5917 // choosing a higher viable VF as done in the loop below. If
5918 // MaxVectorElementCount is scalable, we only fall back on a fixed VF when
5919 // the TC is less than or equal to the known number of lanes.
5920 LLVM_DEBUG(dbgs() << "LV: Clamping the MaxVF to the constant trip count: "do { } while (false)
5921 << ConstTripCount << "\n")do { } while (false);
5922 return TripCountEC;
5923 }
5924
5925 ElementCount MaxVF = MaxVectorElementCount;
5926 if (TTI.shouldMaximizeVectorBandwidth() ||
5927 (MaximizeBandwidth && isScalarEpilogueAllowed())) {
5928 auto MaxVectorElementCountMaxBW = ElementCount::get(
5929 PowerOf2Floor(WidestRegister.getKnownMinSize() / SmallestType),
5930 ComputeScalableMaxVF);
5931 MaxVectorElementCountMaxBW = MinVF(MaxVectorElementCountMaxBW, MaxSafeVF);
5932
5933 // Collect all viable vectorization factors larger than the default MaxVF
5934 // (i.e. MaxVectorElementCount).
5935 SmallVector<ElementCount, 8> VFs;
5936 for (ElementCount VS = MaxVectorElementCount * 2;
5937 ElementCount::isKnownLE(VS, MaxVectorElementCountMaxBW); VS *= 2)
5938 VFs.push_back(VS);
5939
5940 // For each VF calculate its register usage.
5941 auto RUs = calculateRegisterUsage(VFs);
5942
5943 // Select the largest VF which doesn't require more registers than existing
5944 // ones.
5945 for (int i = RUs.size() - 1; i >= 0; --i) {
5946 bool Selected = true;
5947 for (auto &pair : RUs[i].MaxLocalUsers) {
5948 unsigned TargetNumRegisters = TTI.getNumberOfRegisters(pair.first);
5949 if (pair.second > TargetNumRegisters)
5950 Selected = false;
5951 }
5952 if (Selected) {
5953 MaxVF = VFs[i];
5954 break;
5955 }
5956 }
5957 if (ElementCount MinVF =
5958 TTI.getMinimumVF(SmallestType, ComputeScalableMaxVF)) {
5959 if (ElementCount::isKnownLT(MaxVF, MinVF)) {
5960 LLVM_DEBUG(dbgs() << "LV: Overriding calculated MaxVF(" << MaxVFdo { } while (false)
5961 << ") with target's minimum: " << MinVF << '\n')do { } while (false);
5962 MaxVF = MinVF;
5963 }
5964 }
5965 }
5966 return MaxVF;
5967}
5968
5969bool LoopVectorizationCostModel::isMoreProfitable(
5970 const VectorizationFactor &A, const VectorizationFactor &B) const {
5971 InstructionCost CostA = A.Cost;
5972 InstructionCost CostB = B.Cost;
5973
5974 unsigned MaxTripCount = PSE.getSE()->getSmallConstantMaxTripCount(TheLoop);
5975
5976 if (!A.Width.isScalable() && !B.Width.isScalable() && FoldTailByMasking &&
5977 MaxTripCount) {
5978 // If we are folding the tail and the trip count is a known (possibly small)
5979 // constant, the trip count will be rounded up to an integer number of
5980 // iterations. The total cost will be PerIterationCost*ceil(TripCount/VF),
5981 // which we compare directly. When not folding the tail, the total cost will
5982 // be PerIterationCost*floor(TC/VF) + Scalar remainder cost, and so is
5983 // approximated with the per-lane cost below instead of using the tripcount
5984 // as here.
5985 auto RTCostA = CostA * divideCeil(MaxTripCount, A.Width.getFixedValue());
5986 auto RTCostB = CostB * divideCeil(MaxTripCount, B.Width.getFixedValue());
5987 return RTCostA < RTCostB;
5988 }
5989
5990 // When set to preferred, for now assume vscale may be larger than 1, so
5991 // that scalable vectorization is slightly favorable over fixed-width
5992 // vectorization.
5993 if (Hints->isScalableVectorizationPreferred())
5994 if (A.Width.isScalable() && !B.Width.isScalable())
5995 return (CostA * B.Width.getKnownMinValue()) <=
5996 (CostB * A.Width.getKnownMinValue());
5997
5998 // To avoid the need for FP division:
5999 // (CostA / A.Width) < (CostB / B.Width)
6000 // <=> (CostA * B.Width) < (CostB * A.Width)
6001 return (CostA * B.Width.getKnownMinValue()) <
6002 (CostB * A.Width.getKnownMinValue());
6003}
6004
6005VectorizationFactor LoopVectorizationCostModel::selectVectorizationFactor(
6006 const ElementCountSet &VFCandidates) {
6007 InstructionCost ExpectedCost = expectedCost(ElementCount::getFixed(1)).first;
6008 LLVM_DEBUG(dbgs() << "LV: Scalar loop costs: " << ExpectedCost << ".\n")do { } while (false);
6009 assert(ExpectedCost.isValid() && "Unexpected invalid cost for scalar loop")((void)0);
6010 assert(VFCandidates.count(ElementCount::getFixed(1)) &&((void)0)
6011 "Expected Scalar VF to be a candidate")((void)0);
6012
6013 const VectorizationFactor ScalarCost(ElementCount::getFixed(1), ExpectedCost);
6014 VectorizationFactor ChosenFactor = ScalarCost;
6015
6016 bool ForceVectorization = Hints->getForce() == LoopVectorizeHints::FK_Enabled;
6017 if (ForceVectorization && VFCandidates.size() > 1) {
6018 // Ignore scalar width, because the user explicitly wants vectorization.
6019 // Initialize cost to max so that VF = 2 is, at least, chosen during cost
6020 // evaluation.
6021 ChosenFactor.Cost = InstructionCost::getMax();
6022 }
6023
6024 SmallVector<InstructionVFPair> InvalidCosts;
6025 for (const auto &i : VFCandidates) {
6026 // The cost for scalar VF=1 is already calculated, so ignore it.
6027 if (i.isScalar())
6028 continue;
6029
6030 VectorizationCostTy C = expectedCost(i, &InvalidCosts);
6031 VectorizationFactor Candidate(i, C.first);
6032 LLVM_DEBUG(do { } while (false)
6033 dbgs() << "LV: Vector loop of width " << i << " costs: "do { } while (false)
6034 << (Candidate.Cost / Candidate.Width.getKnownMinValue())do { } while (false)
6035 << (i.isScalable() ? " (assuming a minimum vscale of 1)" : "")do { } while (false)
6036 << ".\n")do { } while (false);
6037
6038 if (!C.second && !ForceVectorization) {
6039 LLVM_DEBUG(do { } while (false)
6040 dbgs() << "LV: Not considering vector loop of width " << ido { } while (false)
6041 << " because it will not generate any vector instructions.\n")do { } while (false);
6042 continue;
6043 }
6044
6045 // If profitable add it to ProfitableVF list.
6046 if (isMoreProfitable(Candidate, ScalarCost))
6047 ProfitableVFs.push_back(Candidate);
6048
6049 if (isMoreProfitable(Candidate, ChosenFactor))
6050 ChosenFactor = Candidate;
6051 }
6052
6053 // Emit a report of VFs with invalid costs in the loop.
6054 if (!InvalidCosts.empty()) {
6055 // Group the remarks per instruction, keeping the instruction order from
6056 // InvalidCosts.
6057 std::map<Instruction *, unsigned> Numbering;
6058 unsigned I = 0;
6059 for (auto &Pair : InvalidCosts)
6060 if (!Numbering.count(Pair.first))
6061 Numbering[Pair.first] = I++;
6062
6063 // Sort the list, first on instruction(number) then on VF.
6064 llvm::sort(InvalidCosts,
6065 [&Numbering](InstructionVFPair &A, InstructionVFPair &B) {
6066 if (Numbering[A.first] != Numbering[B.first])
6067 return Numbering[A.first] < Numbering[B.first];
6068 ElementCountComparator ECC;
6069 return ECC(A.second, B.second);
6070 });
6071
6072 // For a list of ordered instruction-vf pairs:
6073 // [(load, vf1), (load, vf2), (store, vf1)]
6074 // Group the instructions together to emit separate remarks for:
6075 // load (vf1, vf2)
6076 // store (vf1)
6077 auto Tail = ArrayRef<InstructionVFPair>(InvalidCosts);
6078 auto Subset = ArrayRef<InstructionVFPair>();
6079 do {
6080 if (Subset.empty())
6081 Subset = Tail.take_front(1);
6082
6083 Instruction *I = Subset.front().first;
6084
6085 // If the next instruction is different, or if there are no other pairs,
6086 // emit a remark for the collated subset. e.g.
6087 // [(load, vf1), (load, vf2))]
6088 // to emit:
6089 // remark: invalid costs for 'load' at VF=(vf, vf2)
6090 if (Subset == Tail || Tail[Subset.size()].first != I) {
6091 std::string OutString;
6092 raw_string_ostream OS(OutString);
6093 assert(!Subset.empty() && "Unexpected empty range")((void)0);
6094 OS << "Instruction with invalid costs prevented vectorization at VF=(";
6095 for (auto &Pair : Subset)
6096 OS << (Pair.second == Subset.front().second ? "" : ", ")
6097 << Pair.second;
6098 OS << "):";
6099 if (auto *CI = dyn_cast<CallInst>(I))
6100 OS << " call to " << CI->getCalledFunction()->getName();
6101 else
6102 OS << " " << I->getOpcodeName();
6103 OS.flush();
6104 reportVectorizationInfo(OutString, "InvalidCost", ORE, TheLoop, I);
6105 Tail = Tail.drop_front(Subset.size());
6106 Subset = {};
6107 } else
6108 // Grow the subset by one element
6109 Subset = Tail.take_front(Subset.size() + 1);
6110 } while (!Tail.empty());
6111 }
6112
6113 if (!EnableCondStoresVectorization && NumPredStores) {
6114 reportVectorizationFailure("There are conditional stores.",
6115 "store that is conditionally executed prevents vectorization",
6116 "ConditionalStore", ORE, TheLoop);
6117 ChosenFactor = ScalarCost;
6118 }
6119
6120 LLVM_DEBUG(if (ForceVectorization && !ChosenFactor.Width.isScalar() &&do { } while (false)
6121 ChosenFactor.Cost >= ScalarCost.Cost) dbgs()do { } while (false)
6122 << "LV: Vectorization seems to be not beneficial, "do { } while (false)
6123 << "but was forced by a user.\n")do { } while (false);
6124 LLVM_DEBUG(dbgs() << "LV: Selecting VF: " << ChosenFactor.Width << ".\n")do { } while (false);
6125 return ChosenFactor;
6126}
6127
6128bool LoopVectorizationCostModel::isCandidateForEpilogueVectorization(
6129 const Loop &L, ElementCount VF) const {
6130 // Cross iteration phis such as reductions need special handling and are
6131 // currently unsupported.
6132 if (any_of(L.getHeader()->phis(), [&](PHINode &Phi) {
6133 return Legal->isFirstOrderRecurrence(&Phi) ||
6134 Legal->isReductionVariable(&Phi);
6135 }))
6136 return false;
6137
6138 // Phis with uses outside of the loop require special handling and are
6139 // currently unsupported.
6140 for (auto &Entry : Legal->getInductionVars()) {
6141 // Look for uses of the value of the induction at the last iteration.
6142 Value *PostInc = Entry.first->getIncomingValueForBlock(L.getLoopLatch());
6143 for (User *U : PostInc->users())
6144 if (!L.contains(cast<Instruction>(U)))
6145 return false;
6146 // Look for uses of penultimate value of the induction.
6147 for (User *U : Entry.first->users())
6148 if (!L.contains(cast<Instruction>(U)))
6149 return false;
6150 }
6151
6152 // Induction variables that are widened require special handling that is
6153 // currently not supported.
6154 if (any_of(Legal->getInductionVars(), [&](auto &Entry) {
6155 return !(this->isScalarAfterVectorization(Entry.first, VF) ||
6156 this->isProfitableToScalarize(Entry.first, VF));
6157 }))
6158 return false;
6159
6160 // Epilogue vectorization code has not been auditted to ensure it handles
6161 // non-latch exits properly. It may be fine, but it needs auditted and
6162 // tested.
6163 if (L.getExitingBlock() != L.getLoopLatch())
6164 return false;
6165
6166 return true;
6167}
6168
6169bool LoopVectorizationCostModel::isEpilogueVectorizationProfitable(
6170 const ElementCount VF) const {
6171 // FIXME: We need a much better cost-model to take different parameters such
6172 // as register pressure, code size increase and cost of extra branches into
6173 // account. For now we apply a very crude heuristic and only consider loops
6174 // with vectorization factors larger than a certain value.
6175 // We also consider epilogue vectorization unprofitable for targets that don't
6176 // consider interleaving beneficial (eg. MVE).
6177 if (TTI.getMaxInterleaveFactor(VF.getKnownMinValue()) <= 1)
6178 return false;
6179 if (VF.getFixedValue() >= EpilogueVectorizationMinVF)
6180 return true;
6181 return false;
6182}
6183
6184VectorizationFactor
6185LoopVectorizationCostModel::selectEpilogueVectorizationFactor(
6186 const ElementCount MainLoopVF, const LoopVectorizationPlanner &LVP) {
6187 VectorizationFactor Result = VectorizationFactor::Disabled();
6188 if (!EnableEpilogueVectorization) {
6189 LLVM_DEBUG(dbgs() << "LEV: Epilogue vectorization is disabled.\n";)do { } while (false);
6190 return Result;
6191 }
6192
6193 if (!isScalarEpilogueAllowed()) {
6194 LLVM_DEBUG(do { } while (false)
6195 dbgs() << "LEV: Unable to vectorize epilogue because no epilogue is "do { } while (false)
6196 "allowed.\n";)do { } while (false);
6197 return Result;
6198 }
6199
6200 // FIXME: This can be fixed for scalable vectors later, because at this stage
6201 // the LoopVectorizer will only consider vectorizing a loop with scalable
6202 // vectors when the loop has a hint to enable vectorization for a given VF.
6203 if (MainLoopVF.isScalable()) {
6204 LLVM_DEBUG(dbgs() << "LEV: Epilogue vectorization for scalable vectors not "do { } while (false)
6205 "yet supported.\n")do { } while (false);
6206 return Result;
6207 }
6208
6209 // Not really a cost consideration, but check for unsupported cases here to
6210 // simplify the logic.
6211 if (!isCandidateForEpilogueVectorization(*TheLoop, MainLoopVF)) {
6212 LLVM_DEBUG(do { } while (false)
6213 dbgs() << "LEV: Unable to vectorize epilogue because the loop is "do { } while (false)
6214 "not a supported candidate.\n";)do { } while (false);
6215 return Result;
6216 }
6217
6218 if (EpilogueVectorizationForceVF > 1) {
6219 LLVM_DEBUG(dbgs() << "LEV: Epilogue vectorization factor is forced.\n";)do { } while (false);
6220 if (LVP.hasPlanWithVFs(
6221 {MainLoopVF, ElementCount::getFixed(EpilogueVectorizationForceVF)}))
6222 return {ElementCount::getFixed(EpilogueVectorizationForceVF), 0};
6223 else {
6224 LLVM_DEBUG(do { } while (false)
6225 dbgs()do { } while (false)
6226 << "LEV: Epilogue vectorization forced factor is not viable.\n";)do { } while (false);
6227 return Result;
6228 }
6229 }
6230
6231 if (TheLoop->getHeader()->getParent()->hasOptSize() ||
6232 TheLoop->getHeader()->getParent()->hasMinSize()) {
6233 LLVM_DEBUG(do { } while (false)
6234 dbgs()do { } while (false)
6235 << "LEV: Epilogue vectorization skipped due to opt for size.\n";)do { } while (false);
6236 return Result;
6237 }
6238
6239 if (!isEpilogueVectorizationProfitable(MainLoopVF))
6240 return Result;
6241
6242 for (auto &NextVF : ProfitableVFs)
6243 if (ElementCount::isKnownLT(NextVF.Width, MainLoopVF) &&
6244 (Result.Width.getFixedValue() == 1 ||
6245 isMoreProfitable(NextVF, Result)) &&
6246 LVP.hasPlanWithVFs({MainLoopVF, NextVF.Width}))
6247 Result = NextVF;
6248
6249 if (Result != VectorizationFactor::Disabled())
6250 LLVM_DEBUG(dbgs() << "LEV: Vectorizing epilogue loop with VF = "do { } while (false)
6251 << Result.Width.getFixedValue() << "\n";)do { } while (false);
6252 return Result;
6253}
6254
6255std::pair<unsigned, unsigned>
6256LoopVectorizationCostModel::getSmallestAndWidestTypes() {
6257 unsigned MinWidth = -1U;
6258 unsigned MaxWidth = 8;
6259 const DataLayout &DL = TheFunction->getParent()->getDataLayout();
6260 for (Type *T : ElementTypesInLoop) {
6261 MinWidth = std::min<unsigned>(
6262 MinWidth, DL.getTypeSizeInBits(T->getScalarType()).getFixedSize());
6263 MaxWidth = std::max<unsigned>(
6264 MaxWidth, DL.getTypeSizeInBits(T->getScalarType()).getFixedSize());
6265 }
6266 return {MinWidth, MaxWidth};
6267}
6268
6269void LoopVectorizationCostModel::collectElementTypesForWidening() {
6270 ElementTypesInLoop.clear();
6271 // For each block.
6272 for (BasicBlock *BB : TheLoop->blocks()) {
6273 // For each instruction in the loop.
6274 for (Instruction &I : BB->instructionsWithoutDebug()) {
6275 Type *T = I.getType();
6276
6277 // Skip ignored values.
6278 if (ValuesToIgnore.count(&I))
6279 continue;
6280
6281 // Only examine Loads, Stores and PHINodes.
6282 if (!isa<LoadInst>(I) && !isa<StoreInst>(I) && !isa<PHINode>(I))
6283 continue;
6284
6285 // Examine PHI nodes that are reduction variables. Update the type to
6286 // account for the recurrence type.
6287 if (auto *PN = dyn_cast<PHINode>(&I)) {
6288 if (!Legal->isReductionVariable(PN))
6289 continue;
6290 const RecurrenceDescriptor &RdxDesc = Legal->getReductionVars()[PN];
6291 if (PreferInLoopReductions || useOrderedReductions(RdxDesc) ||
6292 TTI.preferInLoopReduction(RdxDesc.getOpcode(),
6293 RdxDesc.getRecurrenceType(),
6294 TargetTransformInfo::ReductionFlags()))
6295 continue;
6296 T = RdxDesc.getRecurrenceType();
6297 }
6298
6299 // Examine the stored values.
6300 if (auto *ST = dyn_cast<StoreInst>(&I))
6301 T = ST->getValueOperand()->getType();
6302
6303 // Ignore loaded pointer types and stored pointer types that are not
6304 // vectorizable.
6305 //
6306 // FIXME: The check here attempts to predict whether a load or store will
6307 // be vectorized. We only know this for certain after a VF has
6308 // been selected. Here, we assume that if an access can be
6309 // vectorized, it will be. We should also look at extending this
6310 // optimization to non-pointer types.
6311 //
6312 if (T->isPointerTy() && !isConsecutiveLoadOrStore(&I) &&
6313 !isAccessInterleaved(&I) && !isLegalGatherOrScatter(&I))
6314 continue;
6315
6316 ElementTypesInLoop.insert(T);
6317 }
6318 }
6319}
6320
6321unsigned LoopVectorizationCostModel::selectInterleaveCount(ElementCount VF,
6322 unsigned LoopCost) {
6323 // -- The interleave heuristics --
6324 // We interleave the loop in order to expose ILP and reduce the loop overhead.
6325 // There are many micro-architectural considerations that we can't predict
6326 // at this level. For example, frontend pressure (on decode or fetch) due to
6327 // code size, or the number and capabilities of the execution ports.
6328 //
6329 // We use the following heuristics to select the interleave count:
6330 // 1. If the code has reductions, then we interleave to break the cross
6331 // iteration dependency.
6332 // 2. If the loop is really small, then we interleave to reduce the loop
6333 // overhead.
6334 // 3. We don't interleave if we think that we will spill registers to memory
6335 // due to the increased register pressure.
6336
6337 if (!isScalarEpilogueAllowed())
6338 return 1;
6339
6340 // We used the distance for the interleave count.
6341 if (Legal->getMaxSafeDepDistBytes() != -1U)
6342 return 1;
6343
6344 auto BestKnownTC = getSmallBestKnownTC(*PSE.getSE(), TheLoop);
6345 const bool HasReductions = !Legal->getReductionVars().empty();
6346 // Do not interleave loops with a relatively small known or estimated trip
6347 // count. But we will interleave when InterleaveSmallLoopScalarReduction is
6348 // enabled, and the code has scalar reductions(HasReductions && VF = 1),
6349 // because with the above conditions interleaving can expose ILP and break
6350 // cross iteration dependences for reductions.
6351 if (BestKnownTC && (*BestKnownTC < TinyTripCountInterleaveThreshold) &&
6352 !(InterleaveSmallLoopScalarReduction && HasReductions && VF.isScalar()))
6353 return 1;
6354
6355 RegisterUsage R = calculateRegisterUsage({VF})[0];
6356 // We divide by these constants so assume that we have at least one
6357 // instruction that uses at least one register.
6358 for (auto& pair : R.MaxLocalUsers) {
6359 pair.second = std::max(pair.second, 1U);
6360 }
6361
6362 // We calculate the interleave count using the following formula.
6363 // Subtract the number of loop invariants from the number of available
6364 // registers. These registers are used by all of the interleaved instances.
6365 // Next, divide the remaining registers by the number of registers that is
6366 // required by the loop, in order to estimate how many parallel instances
6367 // fit without causing spills. All of this is rounded down if necessary to be
6368 // a power of two. We want power of two interleave count to simplify any
6369 // addressing operations or alignment considerations.
6370 // We also want power of two interleave counts to ensure that the induction
6371 // variable of the vector loop wraps to zero, when tail is folded by masking;
6372 // this currently happens when OptForSize, in which case IC is set to 1 above.
6373 unsigned IC = UINT_MAX(2147483647 *2U +1U);
6374
6375 for (auto& pair : R.MaxLocalUsers) {
6376 unsigned TargetNumRegisters = TTI.getNumberOfRegisters(pair.first);
6377 LLVM_DEBUG(dbgs() << "LV: The target has " << TargetNumRegistersdo { } while (false)
6378 << " registers of "do { } while (false)
6379 << TTI.getRegisterClassName(pair.first) << " register class\n")do { } while (false);
6380 if (VF.isScalar()) {
6381 if (ForceTargetNumScalarRegs.getNumOccurrences() > 0)
6382 TargetNumRegisters = ForceTargetNumScalarRegs;
6383 } else {
6384 if (ForceTargetNumVectorRegs.getNumOccurrences() > 0)
6385 TargetNumRegisters = ForceTargetNumVectorRegs;
6386 }
6387 unsigned MaxLocalUsers = pair.second;
6388 unsigned LoopInvariantRegs = 0;
6389 if (R.LoopInvariantRegs.find(pair.first) != R.LoopInvariantRegs.end())
6390 LoopInvariantRegs = R.LoopInvariantRegs[pair.first];
6391
6392 unsigned TmpIC = PowerOf2Floor((TargetNumRegisters - LoopInvariantRegs) / MaxLocalUsers);
6393 // Don't count the induction variable as interleaved.
6394 if (EnableIndVarRegisterHeur) {
6395 TmpIC =
6396 PowerOf2Floor((TargetNumRegisters - LoopInvariantRegs - 1) /
6397 std::max(1U, (MaxLocalUsers - 1)));
6398 }
6399
6400 IC = std::min(IC, TmpIC);
6401 }
6402
6403 // Clamp the interleave ranges to reasonable counts.
6404 unsigned MaxInterleaveCount =
6405 TTI.getMaxInterleaveFactor(VF.getKnownMinValue());
6406
6407 // Check if the user has overridden the max.
6408 if (VF.isScalar()) {
6409 if (ForceTargetMaxScalarInterleaveFactor.getNumOccurrences() > 0)
6410 MaxInterleaveCount = ForceTargetMaxScalarInterleaveFactor;
6411 } else {
6412 if (ForceTargetMaxVectorInterleaveFactor.getNumOccurrences() > 0)
6413 MaxInterleaveCount = ForceTargetMaxVectorInterleaveFactor;
6414 }
6415
6416 // If trip count is known or estimated compile time constant, limit the
6417 // interleave count to be less than the trip count divided by VF, provided it
6418 // is at least 1.
6419 //
6420 // For scalable vectors we can't know if interleaving is beneficial. It may
6421 // not be beneficial for small loops if none of the lanes in the second vector
6422 // iterations is enabled. However, for larger loops, there is likely to be a
6423 // similar benefit as for fixed-width vectors. For now, we choose to leave
6424 // the InterleaveCount as if vscale is '1', although if some information about
6425 // the vector is known (e.g. min vector size), we can make a better decision.
6426 if (BestKnownTC) {
6427 MaxInterleaveCount =
6428 std::min(*BestKnownTC / VF.getKnownMinValue(), MaxInterleaveCount);
6429 // Make sure MaxInterleaveCount is greater than 0.
6430 MaxInterleaveCount = std::max(1u, MaxInterleaveCount);
6431 }
6432
6433 assert(MaxInterleaveCount > 0 &&((void)0)
6434 "Maximum interleave count must be greater than 0")((void)0);
6435
6436 // Clamp the calculated IC to be between the 1 and the max interleave count
6437 // that the target and trip count allows.
6438 if (IC > MaxInterleaveCount)
6439 IC = MaxInterleaveCount;
6440 else
6441 // Make sure IC is greater than 0.
6442 IC = std::max(1u, IC);
6443
6444 assert(IC > 0 && "Interleave count must be greater than 0.")((void)0);
6445
6446 // If we did not calculate the cost for VF (because the user selected the VF)
6447 // then we calculate the cost of VF here.
6448 if (LoopCost == 0) {
6449 InstructionCost C = expectedCost(VF).first;
6450 assert(C.isValid() && "Expected to have chosen a VF with valid cost")((void)0);
6451 LoopCost = *C.getValue();
6452 }
6453
6454 assert(LoopCost && "Non-zero loop cost expected")((void)0);
6455
6456 // Interleave if we vectorized this loop and there is a reduction that could
6457 // benefit from interleaving.
6458 if (VF.isVector() && HasReductions) {
6459 LLVM_DEBUG(dbgs() << "LV: Interleaving because of reductions.\n")do { } while (false);
6460 return IC;
6461 }
6462
6463 // Note that if we've already vectorized the loop we will have done the
6464 // runtime check and so interleaving won't require further checks.
6465 bool InterleavingRequiresRuntimePointerCheck =
6466 (VF.isScalar() && Legal->getRuntimePointerChecking()->Need);
6467
6468 // We want to interleave small loops in order to reduce the loop overhead and
6469 // potentially expose ILP opportunities.
6470 LLVM_DEBUG(dbgs() << "LV: Loop cost is " << LoopCost << '\n'do { } while (false)
6471 << "LV: IC is " << IC << '\n'do { } while (false)
6472 << "LV: VF is " << VF << '\n')do { } while (false);
6473 const bool AggressivelyInterleaveReductions =
6474 TTI.enableAggressiveInterleaving(HasReductions);
6475 if (!InterleavingRequiresRuntimePointerCheck && LoopCost < SmallLoopCost) {
6476 // We assume that the cost overhead is 1 and we use the cost model
6477 // to estimate the cost of the loop and interleave until the cost of the
6478 // loop overhead is about 5% of the cost of the loop.
6479 unsigned SmallIC =
6480 std::min(IC, (unsigned)PowerOf2Floor(SmallLoopCost / LoopCost));
6481
6482 // Interleave until store/load ports (estimated by max interleave count) are
6483 // saturated.
6484 unsigned NumStores = Legal->getNumStores();
6485 unsigned NumLoads = Legal->getNumLoads();
6486 unsigned StoresIC = IC / (NumStores ? NumStores : 1);
6487 unsigned LoadsIC = IC / (NumLoads ? NumLoads : 1);
6488
6489 // If we have a scalar reduction (vector reductions are already dealt with
6490 // by this point), we can increase the critical path length if the loop
6491 // we're interleaving is inside another loop. For tree-wise reductions
6492 // set the limit to 2, and for ordered reductions it's best to disable
6493 // interleaving entirely.
6494 if (HasReductions && TheLoop->getLoopDepth() > 1) {
6495 bool HasOrderedReductions =
6496 any_of(Legal->getReductionVars(), [&](auto &Reduction) -> bool {
6497 const RecurrenceDescriptor &RdxDesc = Reduction.second;
6498 return RdxDesc.isOrdered();
6499 });
6500 if (HasOrderedReductions) {
6501 LLVM_DEBUG(do { } while (false)
6502 dbgs() << "LV: Not interleaving scalar ordered reductions.\n")do { } while (false);
6503 return 1;
6504 }
6505
6506 unsigned F = static_cast<unsigned>(MaxNestedScalarReductionIC);
6507 SmallIC = std::min(SmallIC, F);
6508 StoresIC = std::min(StoresIC, F);
6509 LoadsIC = std::min(LoadsIC, F);
6510 }
6511
6512 if (EnableLoadStoreRuntimeInterleave &&
6513 std::max(StoresIC, LoadsIC) > SmallIC) {
6514 LLVM_DEBUG(do { } while (false)
6515 dbgs() << "LV: Interleaving to saturate store or load ports.\n")do { } while (false);
6516 return std::max(StoresIC, LoadsIC);
6517 }
6518
6519 // If there are scalar reductions and TTI has enabled aggressive
6520 // interleaving for reductions, we will interleave to expose ILP.
6521 if (InterleaveSmallLoopScalarReduction && VF.isScalar() &&
6522 AggressivelyInterleaveReductions) {
6523 LLVM_DEBUG(dbgs() << "LV: Interleaving to expose ILP.\n")do { } while (false);
6524 // Interleave no less than SmallIC but not as aggressive as the normal IC
6525 // to satisfy the rare situation when resources are too limited.
6526 return std::max(IC / 2, SmallIC);
6527 } else {
6528 LLVM_DEBUG(dbgs() << "LV: Interleaving to reduce branch cost.\n")do { } while (false);
6529 return SmallIC;
6530 }
6531 }
6532
6533 // Interleave if this is a large loop (small loops are already dealt with by
6534 // this point) that could benefit from interleaving.
6535 if (AggressivelyInterleaveReductions) {
6536 LLVM_DEBUG(dbgs() << "LV: Interleaving to expose ILP.\n")do { } while (false);
6537 return IC;
6538 }
6539
6540 LLVM_DEBUG(dbgs() << "LV: Not Interleaving.\n")do { } while (false);
6541 return 1;
6542}
6543
6544SmallVector<LoopVectorizationCostModel::RegisterUsage, 8>
6545LoopVectorizationCostModel::calculateRegisterUsage(ArrayRef<ElementCount> VFs) {
6546 // This function calculates the register usage by measuring the highest number
6547 // of values that are alive at a single location. Obviously, this is a very
6548 // rough estimation. We scan the loop in a topological order in order and
6549 // assign a number to each instruction. We use RPO to ensure that defs are
6550 // met before their users. We assume that each instruction that has in-loop
6551 // users starts an interval. We record every time that an in-loop value is
6552 // used, so we have a list of the first and last occurrences of each
6553 // instruction. Next, we transpose this data structure into a multi map that
6554 // holds the list of intervals that *end* at a specific location. This multi
6555 // map allows us to perform a linear search. We scan the instructions linearly
6556 // and record each time that a new interval starts, by placing it in a set.
6557 // If we find this value in the multi-map then we remove it from the set.
6558 // The max register usage is the maximum size of the set.
6559 // We also search for instructions that are defined outside the loop, but are
6560 // used inside the loop. We need this number separately from the max-interval
6561 // usage number because when we unroll, loop-invariant values do not take
6562 // more register.
6563 LoopBlocksDFS DFS(TheLoop);
6564 DFS.perform(LI);
6565
6566 RegisterUsage RU;
6567
6568 // Each 'key' in the map opens a new interval. The values
6569 // of the map are the index of the 'last seen' usage of the
6570 // instruction that is the key.
6571 using IntervalMap = DenseMap<Instruction *, unsigned>;
6572
6573 // Maps instruction to its index.
6574 SmallVector<Instruction *, 64> IdxToInstr;
6575 // Marks the end of each interval.
6576 IntervalMap EndPoint;
6577 // Saves the list of instruction indices that are used in the loop.
6578 SmallPtrSet<Instruction *, 8> Ends;
6579 // Saves the list of values that are used in the loop but are
6580 // defined outside the loop, such as arguments and constants.
6581 SmallPtrSet<Value *, 8> LoopInvariants;
6582
6583 for (BasicBlock *BB : make_range(DFS.beginRPO(), DFS.endRPO())) {
6584 for (Instruction &I : BB->instructionsWithoutDebug()) {
6585 IdxToInstr.push_back(&I);
6586
6587 // Save the end location of each USE.
6588 for (Value *U : I.operands()) {
6589 auto *Instr = dyn_cast<Instruction>(U);
6590
6591 // Ignore non-instruction values such as arguments, constants, etc.
6592 if (!Instr)
6593 continue;
6594
6595 // If this instruction is outside the loop then record it and continue.
6596 if (!TheLoop->contains(Instr)) {
6597 LoopInvariants.insert(Instr);
6598 continue;
6599 }
6600
6601 // Overwrite previous end points.
6602 EndPoint[Instr] = IdxToInstr.size();
6603 Ends.insert(Instr);
6604 }
6605 }
6606 }
6607
6608 // Saves the list of intervals that end with the index in 'key'.
6609 using InstrList = SmallVector<Instruction *, 2>;
6610 DenseMap<unsigned, InstrList> TransposeEnds;
6611
6612 // Transpose the EndPoints to a list of values that end at each index.
6613 for (auto &Interval : EndPoint)
6614 TransposeEnds[Interval.second].push_back(Interval.first);
6615
6616 SmallPtrSet<Instruction *, 8> OpenIntervals;
6617 SmallVector<RegisterUsage, 8> RUs(VFs.size());
6618 SmallVector<SmallMapVector<unsigned, unsigned, 4>, 8> MaxUsages(VFs.size());
6619
6620 LLVM_DEBUG(dbgs() << "LV(REG): Calculating max register usage:\n")do { } while (false);
6621
6622 // A lambda that gets the register usage for the given type and VF.
6623 const auto &TTICapture = TTI;
6624 auto GetRegUsage = [&TTICapture](Type *Ty, ElementCount VF) -> unsigned {
6625 if (Ty->isTokenTy() || !VectorType::isValidElementType(Ty))
6626 return 0;
6627 InstructionCost::CostType RegUsage =
6628 *TTICapture.getRegUsageForType(VectorType::get(Ty, VF)).getValue();
6629 assert(RegUsage >= 0 && RegUsage <= std::numeric_limits<unsigned>::max() &&((void)0)
6630 "Nonsensical values for register usage.")((void)0);
6631 return RegUsage;
6632 };
6633
6634 for (unsigned int i = 0, s = IdxToInstr.size(); i < s; ++i) {
6635 Instruction *I = IdxToInstr[i];
6636
6637 // Remove all of the instructions that end at this location.
6638 InstrList &List = TransposeEnds[i];
6639 for (Instruction *ToRemove : List)
6640 OpenIntervals.erase(ToRemove);
6641
6642 // Ignore instructions that are never used within the loop.
6643 if (!Ends.count(I))
6644 continue;
6645
6646 // Skip ignored values.
6647 if (ValuesToIgnore.count(I))
6648 continue;
6649
6650 // For each VF find the maximum usage of registers.
6651 for (unsigned j = 0, e = VFs.size(); j < e; ++j) {
6652 // Count the number of live intervals.
6653 SmallMapVector<unsigned, unsigned, 4> RegUsage;
6654
6655 if (VFs[j].isScalar()) {
6656 for (auto Inst : OpenIntervals) {
6657 unsigned ClassID = TTI.getRegisterClassForType(false, Inst->getType());
6658 if (RegUsage.find(ClassID) == RegUsage.end())
6659 RegUsage[ClassID] = 1;
6660 else
6661 RegUsage[ClassID] += 1;
6662 }
6663 } else {
6664 collectUniformsAndScalars(VFs[j]);
6665 for (auto Inst : OpenIntervals) {
6666 // Skip ignored values for VF > 1.
6667 if (VecValuesToIgnore.count(Inst))
6668 continue;
6669 if (isScalarAfterVectorization(Inst, VFs[j])) {
6670 unsigned ClassID = TTI.getRegisterClassForType(false, Inst->getType());
6671 if (RegUsage.find(ClassID) == RegUsage.end())
6672 RegUsage[ClassID] = 1;
6673 else
6674 RegUsage[ClassID] += 1;
6675 } else {
6676 unsigned ClassID = TTI.getRegisterClassForType(true, Inst->getType());
6677 if (RegUsage.find(ClassID) == RegUsage.end())
6678 RegUsage[ClassID] = GetRegUsage(Inst->getType(), VFs[j]);
6679 else
6680 RegUsage[ClassID] += GetRegUsage(Inst->getType(), VFs[j]);
6681 }
6682 }
6683 }
6684
6685 for (auto& pair : RegUsage) {
6686 if (MaxUsages[j].find(pair.first) != MaxUsages[j].end())
6687 MaxUsages[j][pair.first] = std::max(MaxUsages[j][pair.first], pair.second);
6688 else
6689 MaxUsages[j][pair.first] = pair.second;
6690 }
6691 }
6692
6693 LLVM_DEBUG(dbgs() << "LV(REG): At #" << i << " Interval # "do { } while (false)
6694 << OpenIntervals.size() << '\n')do { } while (false);
6695
6696 // Add the current instruction to the list of open intervals.
6697 OpenIntervals.insert(I);
6698 }
6699
6700 for (unsigned i = 0, e = VFs.size(); i < e; ++i) {
6701 SmallMapVector<unsigned, unsigned, 4> Invariant;
6702
6703 for (auto Inst : LoopInvariants) {
6704 unsigned Usage =
6705 VFs[i].isScalar() ? 1 : GetRegUsage(Inst->getType(), VFs[i]);
6706 unsigned ClassID =
6707 TTI.getRegisterClassForType(VFs[i].isVector(), Inst->getType());
6708 if (Invariant.find(ClassID) == Invariant.end())
6709 Invariant[ClassID] = Usage;
6710 else
6711 Invariant[ClassID] += Usage;
6712 }
6713
6714 LLVM_DEBUG({do { } while (false)
6715 dbgs() << "LV(REG): VF = " << VFs[i] << '\n';do { } while (false)
6716 dbgs() << "LV(REG): Found max usage: " << MaxUsages[i].size()do { } while (false)
6717 << " item\n";do { } while (false)
6718 for (const auto &pair : MaxUsages[i]) {do { } while (false)
6719 dbgs() << "LV(REG): RegisterClass: "do { } while (false)
6720 << TTI.getRegisterClassName(pair.first) << ", " << pair.seconddo { } while (false)
6721 << " registers\n";do { } while (false)
6722 }do { } while (false)
6723 dbgs() << "LV(REG): Found invariant usage: " << Invariant.size()do { } while (false)
6724 << " item\n";do { } while (false)
6725 for (const auto &pair : Invariant) {do { } while (false)
6726 dbgs() << "LV(REG): RegisterClass: "do { } while (false)
6727 << TTI.getRegisterClassName(pair.first) << ", " << pair.seconddo { } while (false)
6728 << " registers\n";do { } while (false)
6729 }do { } while (false)
6730 })do { } while (false);
6731
6732 RU.LoopInvariantRegs = Invariant;
6733 RU.MaxLocalUsers = MaxUsages[i];
6734 RUs[i] = RU;
6735 }
6736
6737 return RUs;
6738}
6739
6740bool LoopVectorizationCostModel::useEmulatedMaskMemRefHack(Instruction *I){
6741 // TODO: Cost model for emulated masked load/store is completely
6742 // broken. This hack guides the cost model to use an artificially
6743 // high enough value to practically disable vectorization with such
6744 // operations, except where previously deployed legality hack allowed
6745 // using very low cost values. This is to avoid regressions coming simply
6746 // from moving "masked load/store" check from legality to cost model.
6747 // Masked Load/Gather emulation was previously never allowed.
6748 // Limited number of Masked Store/Scatter emulation was allowed.
6749 assert(isPredicatedInst(I) &&((void)0)
6750 "Expecting a scalar emulated instruction")((void)0);
6751 return isa<LoadInst>(I) ||
6752 (isa<StoreInst>(I) &&
6753 NumPredStores > NumberOfStoresToPredicate);
6754}
6755
6756void LoopVectorizationCostModel::collectInstsToScalarize(ElementCount VF) {
6757 // If we aren't vectorizing the loop, or if we've already collected the
6758 // instructions to scalarize, there's nothing to do. Collection may already
6759 // have occurred if we have a user-selected VF and are now computing the
6760 // expected cost for interleaving.
6761 if (VF.isScalar() || VF.isZero() ||
6762 InstsToScalarize.find(VF) != InstsToScalarize.end())
6763 return;
6764
6765 // Initialize a mapping for VF in InstsToScalalarize. If we find that it's
6766 // not profitable to scalarize any instructions, the presence of VF in the
6767 // map will indicate that we've analyzed it already.
6768 ScalarCostsTy &ScalarCostsVF = InstsToScalarize[VF];
6769
6770 // Find all the instructions that are scalar with predication in the loop and
6771 // determine if it would be better to not if-convert the blocks they are in.
6772 // If so, we also record the instructions to scalarize.
6773 for (BasicBlock *BB : TheLoop->blocks()) {
6774 if (!blockNeedsPredication(BB))
6775 continue;
6776 for (Instruction &I : *BB)
6777 if (isScalarWithPredication(&I)) {
6778 ScalarCostsTy ScalarCosts;
6779 // Do not apply discount if scalable, because that would lead to
6780 // invalid scalarization costs.
6781 // Do not apply discount logic if hacked cost is needed
6782 // for emulated masked memrefs.
6783 if (!VF.isScalable() && !useEmulatedMaskMemRefHack(&I) &&
6784 computePredInstDiscount(&I, ScalarCosts, VF) >= 0)
6785 ScalarCostsVF.insert(ScalarCosts.begin(), ScalarCosts.end());
6786 // Remember that BB will remain after vectorization.
6787 PredicatedBBsAfterVectorization.insert(BB);
6788 }
6789 }
6790}
6791
6792int LoopVectorizationCostModel::computePredInstDiscount(
6793 Instruction *PredInst, ScalarCostsTy &ScalarCosts, ElementCount VF) {
6794 assert(!isUniformAfterVectorization(PredInst, VF) &&((void)0)
6795 "Instruction marked uniform-after-vectorization will be predicated")((void)0);
6796
6797 // Initialize the discount to zero, meaning that the scalar version and the
6798 // vector version cost the same.
6799 InstructionCost Discount = 0;
6800
6801 // Holds instructions to analyze. The instructions we visit are mapped in
6802 // ScalarCosts. Those instructions are the ones that would be scalarized if
6803 // we find that the scalar version costs less.
6804 SmallVector<Instruction *, 8> Worklist;
6805
6806 // Returns true if the given instruction can be scalarized.
6807 auto canBeScalarized = [&](Instruction *I) -> bool {
6808 // We only attempt to scalarize instructions forming a single-use chain
6809 // from the original predicated block that would otherwise be vectorized.
6810 // Although not strictly necessary, we give up on instructions we know will
6811 // already be scalar to avoid traversing chains that are unlikely to be
6812 // beneficial.
6813 if (!I->hasOneUse() || PredInst->getParent() != I->getParent() ||
6814 isScalarAfterVectorization(I, VF))
6815 return false;
6816
6817 // If the instruction is scalar with predication, it will be analyzed
6818 // separately. We ignore it within the context of PredInst.
6819 if (isScalarWithPredication(I))
6820 return false;
6821
6822 // If any of the instruction's operands are uniform after vectorization,
6823 // the instruction cannot be scalarized. This prevents, for example, a
6824 // masked load from being scalarized.
6825 //
6826 // We assume we will only emit a value for lane zero of an instruction
6827 // marked uniform after vectorization, rather than VF identical values.
6828 // Thus, if we scalarize an instruction that uses a uniform, we would
6829 // create uses of values corresponding to the lanes we aren't emitting code
6830 // for. This behavior can be changed by allowing getScalarValue to clone
6831 // the lane zero values for uniforms rather than asserting.
6832 for (Use &U : I->operands())
6833 if (auto *J = dyn_cast<Instruction>(U.get()))
6834 if (isUniformAfterVectorization(J, VF))
6835 return false;
6836
6837 // Otherwise, we can scalarize the instruction.
6838 return true;
6839 };
6840
6841 // Compute the expected cost discount from scalarizing the entire expression
6842 // feeding the predicated instruction. We currently only consider expressions
6843 // that are single-use instruction chains.
6844 Worklist.push_back(PredInst);
6845 while (!Worklist.empty()) {
6846 Instruction *I = Worklist.pop_back_val();
6847
6848 // If we've already analyzed the instruction, there's nothing to do.
6849 if (ScalarCosts.find(I) != ScalarCosts.end())
6850 continue;
6851
6852 // Compute the cost of the vector instruction. Note that this cost already
6853 // includes the scalarization overhead of the predicated instruction.
6854 InstructionCost VectorCost = getInstructionCost(I, VF).first;
6855
6856 // Compute the cost of the scalarized instruction. This cost is the cost of
6857 // the instruction as if it wasn't if-converted and instead remained in the
6858 // predicated block. We will scale this cost by block probability after
6859 // computing the scalarization overhead.
6860 InstructionCost ScalarCost =
6861 VF.getFixedValue() *
6862 getInstructionCost(I, ElementCount::getFixed(1)).first;
6863
6864 // Compute the scalarization overhead of needed insertelement instructions
6865 // and phi nodes.
6866 if (isScalarWithPredication(I) && !I->getType()->isVoidTy()) {
6867 ScalarCost += TTI.getScalarizationOverhead(
6868 cast<VectorType>(ToVectorTy(I->getType(), VF)),
6869 APInt::getAllOnesValue(VF.getFixedValue()), true, false);
6870 ScalarCost +=
6871 VF.getFixedValue() *
6872 TTI.getCFInstrCost(Instruction::PHI, TTI::TCK_RecipThroughput);
6873 }
6874
6875 // Compute the scalarization overhead of needed extractelement
6876 // instructions. For each of the instruction's operands, if the operand can
6877 // be scalarized, add it to the worklist; otherwise, account for the
6878 // overhead.
6879 for (Use &U : I->operands())
6880 if (auto *J = dyn_cast<Instruction>(U.get())) {
6881 assert(VectorType::isValidElementType(J->getType()) &&((void)0)
6882 "Instruction has non-scalar type")((void)0);
6883 if (canBeScalarized(J))
6884 Worklist.push_back(J);
6885 else if (needsExtract(J, VF)) {
6886 ScalarCost += TTI.getScalarizationOverhead(
6887 cast<VectorType>(ToVectorTy(J->getType(), VF)),
6888 APInt::getAllOnesValue(VF.getFixedValue()), false, true);
6889 }
6890 }
6891
6892 // Scale the total scalar cost by block probability.
6893 ScalarCost /= getReciprocalPredBlockProb();
6894
6895 // Compute the discount. A non-negative discount means the vector version
6896 // of the instruction costs more, and scalarizing would be beneficial.
6897 Discount += VectorCost - ScalarCost;
6898 ScalarCosts[I] = ScalarCost;
6899 }
6900
6901 return *Discount.getValue();
6902}
6903
6904LoopVectorizationCostModel::VectorizationCostTy
6905LoopVectorizationCostModel::expectedCost(
6906 ElementCount VF, SmallVectorImpl<InstructionVFPair> *Invalid) {
6907 VectorizationCostTy Cost;
6908
6909 // For each block.
6910 for (BasicBlock *BB : TheLoop->blocks()) {
6911 VectorizationCostTy BlockCost;
6912
6913 // For each instruction in the old loop.
6914 for (Instruction &I : BB->instructionsWithoutDebug()) {
6915 // Skip ignored values.
6916 if (ValuesToIgnore.count(&I) ||
6917 (VF.isVector() && VecValuesToIgnore.count(&I)))
6918 continue;
6919
6920 VectorizationCostTy C = getInstructionCost(&I, VF);
6921
6922 // Check if we should override the cost.
6923 if (C.first.isValid() &&
6924 ForceTargetInstructionCost.getNumOccurrences() > 0)
6925 C.first = InstructionCost(ForceTargetInstructionCost);
6926
6927 // Keep a list of instructions with invalid costs.
6928 if (Invalid && !C.first.isValid())
6929 Invalid->emplace_back(&I, VF);
6930
6931 BlockCost.first += C.first;
6932 BlockCost.second |= C.second;
6933 LLVM_DEBUG(dbgs() << "LV: Found an estimated cost of " << C.firstdo { } while (false)
6934 << " for VF " << VF << " For instruction: " << Ido { } while (false)
6935 << '\n')do { } while (false);
6936 }
6937
6938 // If we are vectorizing a predicated block, it will have been
6939 // if-converted. This means that the block's instructions (aside from
6940 // stores and instructions that may divide by zero) will now be
6941 // unconditionally executed. For the scalar case, we may not always execute
6942 // the predicated block, if it is an if-else block. Thus, scale the block's
6943 // cost by the probability of executing it. blockNeedsPredication from
6944 // Legal is used so as to not include all blocks in tail folded loops.
6945 if (VF.isScalar() && Legal->blockNeedsPredication(BB))
6946 BlockCost.first /= getReciprocalPredBlockProb();
6947
6948 Cost.first += BlockCost.first;
6949 Cost.second |= BlockCost.second;
6950 }
6951
6952 return Cost;
6953}
6954
6955/// Gets Address Access SCEV after verifying that the access pattern
6956/// is loop invariant except the induction variable dependence.
6957///
6958/// This SCEV can be sent to the Target in order to estimate the address
6959/// calculation cost.
6960static const SCEV *getAddressAccessSCEV(
6961 Value *Ptr,
6962 LoopVectorizationLegality *Legal,
6963 PredicatedScalarEvolution &PSE,
6964 const Loop *TheLoop) {
6965
6966 auto *Gep = dyn_cast<GetElementPtrInst>(Ptr);
6967 if (!Gep)
6968 return nullptr;
6969
6970 // We are looking for a gep with all loop invariant indices except for one
6971 // which should be an induction variable.
6972 auto SE = PSE.getSE();
6973 unsigned NumOperands = Gep->getNumOperands();
6974 for (unsigned i = 1; i < NumOperands; ++i) {
6975 Value *Opd = Gep->getOperand(i);
6976 if (!SE->isLoopInvariant(SE->getSCEV(Opd), TheLoop) &&
6977 !Legal->isInductionVariable(Opd))
6978 return nullptr;
6979 }
6980
6981 // Now we know we have a GEP ptr, %inv, %ind, %inv. return the Ptr SCEV.
6982 return PSE.getSCEV(Ptr);
6983}
6984
6985static bool isStrideMul(Instruction *I, LoopVectorizationLegality *Legal) {
6986 return Legal->hasStride(I->getOperand(0)) ||
6987 Legal->hasStride(I->getOperand(1));
6988}
6989
6990InstructionCost
6991LoopVectorizationCostModel::getMemInstScalarizationCost(Instruction *I,
6992 ElementCount VF) {
6993 assert(VF.isVector() &&((void)0)
6994 "Scalarization cost of instruction implies vectorization.")((void)0);
6995 if (VF.isScalable())
6996 return InstructionCost::getInvalid();
6997
6998 Type *ValTy = getLoadStoreType(I);
6999 auto SE = PSE.getSE();
7000
7001 unsigned AS = getLoadStoreAddressSpace(I);
7002 Value *Ptr = getLoadStorePointerOperand(I);
7003 Type *PtrTy = ToVectorTy(Ptr->getType(), VF);
7004
7005 // Figure out whether the access is strided and get the stride value
7006 // if it's known in compile time
7007 const SCEV *PtrSCEV = getAddressAccessSCEV(Ptr, Legal, PSE, TheLoop);
7008
7009 // Get the cost of the scalar memory instruction and address computation.
7010 InstructionCost Cost =
7011 VF.getKnownMinValue() * TTI.getAddressComputationCost(PtrTy, SE, PtrSCEV);
7012
7013 // Don't pass *I here, since it is scalar but will actually be part of a
7014 // vectorized loop where the user of it is a vectorized instruction.
7015 const Align Alignment = getLoadStoreAlignment(I);
7016 Cost += VF.getKnownMinValue() *
7017 TTI.getMemoryOpCost(I->getOpcode(), ValTy->getScalarType(), Alignment,
7018 AS, TTI::TCK_RecipThroughput);
7019
7020 // Get the overhead of the extractelement and insertelement instructions
7021 // we might create due to scalarization.
7022 Cost += getScalarizationOverhead(I, VF);
7023
7024 // If we have a predicated load/store, it will need extra i1 extracts and
7025 // conditional branches, but may not be executed for each vector lane. Scale
7026 // the cost by the probability of executing the predicated block.
7027 if (isPredicatedInst(I)) {
7028 Cost /= getReciprocalPredBlockProb();
7029
7030 // Add the cost of an i1 extract and a branch
7031 auto *Vec_i1Ty =
7032 VectorType::get(IntegerType::getInt1Ty(ValTy->getContext()), VF);
7033 Cost += TTI.getScalarizationOverhead(
7034 Vec_i1Ty, APInt::getAllOnesValue(VF.getKnownMinValue()),
7035 /*Insert=*/false, /*Extract=*/true);
7036 Cost += TTI.getCFInstrCost(Instruction::Br, TTI::TCK_RecipThroughput);
7037
7038 if (useEmulatedMaskMemRefHack(I))
7039 // Artificially setting to a high enough value to practically disable
7040 // vectorization with such operations.
7041 Cost = 3000000;
7042 }
7043
7044 return Cost;
7045}
7046
7047InstructionCost
7048LoopVectorizationCostModel::getConsecutiveMemOpCost(Instruction *I,
7049 ElementCount VF) {
7050 Type *ValTy = getLoadStoreType(I);
7051 auto *VectorTy = cast<VectorType>(ToVectorTy(ValTy, VF));
7052 Value *Ptr = getLoadStorePointerOperand(I);
7053 unsigned AS = getLoadStoreAddressSpace(I);
7054 int ConsecutiveStride = Legal->isConsecutivePtr(Ptr);
7055 enum TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
7056
7057 assert((ConsecutiveStride == 1 || ConsecutiveStride == -1) &&((void)0)
7058 "Stride should be 1 or -1 for consecutive memory access")((void)0);
7059 const Align Alignment = getLoadStoreAlignment(I);
7060 InstructionCost Cost = 0;
7061 if (Legal->isMaskRequired(I))
7062 Cost += TTI.getMaskedMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS,
7063 CostKind);
7064 else
7065 Cost += TTI.getMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS,
7066 CostKind, I);
7067
7068 bool Reverse = ConsecutiveStride < 0;
7069 if (Reverse)
7070 Cost +=
7071 TTI.getShuffleCost(TargetTransformInfo::SK_Reverse, VectorTy, None, 0);
7072 return Cost;
7073}
7074
7075InstructionCost
7076LoopVectorizationCostModel::getUniformMemOpCost(Instruction *I,
7077 ElementCount VF) {
7078 assert(Legal->isUniformMemOp(*I))((void)0);
7079
7080 Type *ValTy = getLoadStoreType(I);
7081 auto *VectorTy = cast<VectorType>(ToVectorTy(ValTy, VF));
7082 const Align Alignment = getLoadStoreAlignment(I);
7083 unsigned AS = getLoadStoreAddressSpace(I);
7084 enum TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
7085 if (isa<LoadInst>(I)) {
7086 return TTI.getAddressComputationCost(ValTy) +
7087 TTI.getMemoryOpCost(Instruction::Load, ValTy, Alignment, AS,
7088 CostKind) +
7089 TTI.getShuffleCost(TargetTransformInfo::SK_Broadcast, VectorTy);
7090 }
7091 StoreInst *SI = cast<StoreInst>(I);
7092
7093 bool isLoopInvariantStoreValue = Legal->isUniform(SI->getValueOperand());
7094 return TTI.getAddressComputationCost(ValTy) +
7095 TTI.getMemoryOpCost(Instruction::Store, ValTy, Alignment, AS,
7096 CostKind) +
7097 (isLoopInvariantStoreValue
7098 ? 0
7099 : TTI.getVectorInstrCost(Instruction::ExtractElement, VectorTy,
7100 VF.getKnownMinValue() - 1));
7101}
7102
7103InstructionCost
7104LoopVectorizationCostModel::getGatherScatterCost(Instruction *I,
7105 ElementCount VF) {
7106 Type *ValTy = getLoadStoreType(I);
7107 auto *VectorTy = cast<VectorType>(ToVectorTy(ValTy, VF));
7108 const Align Alignment = getLoadStoreAlignment(I);
7109 const Value *Ptr = getLoadStorePointerOperand(I);
7110
7111 return TTI.getAddressComputationCost(VectorTy) +
7112 TTI.getGatherScatterOpCost(
7113 I->getOpcode(), VectorTy, Ptr, Legal->isMaskRequired(I), Alignment,
7114 TargetTransformInfo::TCK_RecipThroughput, I);
7115}
7116
7117InstructionCost
7118LoopVectorizationCostModel::getInterleaveGroupCost(Instruction *I,
7119 ElementCount VF) {
7120 // TODO: Once we have support for interleaving with scalable vectors
7121 // we can calculate the cost properly here.
7122 if (VF.isScalable())
7123 return InstructionCost::getInvalid();
7124
7125 Type *ValTy = getLoadStoreType(I);
7126 auto *VectorTy = cast<VectorType>(ToVectorTy(ValTy, VF));
7127 unsigned AS = getLoadStoreAddressSpace(I);
7128
7129 auto Group = getInterleavedAccessGroup(I);
7130 assert(Group && "Fail to get an interleaved access group.")((void)0);
7131
7132 unsigned InterleaveFactor = Group->getFactor();
7133 auto *WideVecTy = VectorType::get(ValTy, VF * InterleaveFactor);
7134
7135 // Holds the indices of existing members in an interleaved load group.
7136 // An interleaved store group doesn't need this as it doesn't allow gaps.
7137 SmallVector<unsigned, 4> Indices;
7138 if (isa<LoadInst>(I)) {
7139 for (unsigned i = 0; i < InterleaveFactor; i++)
7140 if (Group->getMember(i))
7141 Indices.push_back(i);
7142 }
7143
7144 // Calculate the cost of the whole interleaved group.
7145 bool UseMaskForGaps =
7146 Group->requiresScalarEpilogue() && !isScalarEpilogueAllowed();
7147 InstructionCost Cost = TTI.getInterleavedMemoryOpCost(
7148 I->getOpcode(), WideVecTy, Group->getFactor(), Indices, Group->getAlign(),
7149 AS, TTI::TCK_RecipThroughput, Legal->isMaskRequired(I), UseMaskForGaps);
7150
7151 if (Group->isReverse()) {
7152 // TODO: Add support for reversed masked interleaved access.
7153 assert(!Legal->isMaskRequired(I) &&((void)0)
7154 "Reverse masked interleaved access not supported.")((void)0);
7155 Cost +=
7156 Group->getNumMembers() *
7157 TTI.getShuffleCost(TargetTransformInfo::SK_Reverse, VectorTy, None, 0);
7158 }
7159 return Cost;
7160}
7161
7162Optional<InstructionCost> LoopVectorizationCostModel::getReductionPatternCost(
7163 Instruction *I, ElementCount VF, Type *Ty, TTI::TargetCostKind CostKind) {
7164 using namespace llvm::PatternMatch;
7165 // Early exit for no inloop reductions
7166 if (InLoopReductionChains.empty() || VF.isScalar() || !isa<VectorType>(Ty))
7167 return None;
7168 auto *VectorTy = cast<VectorType>(Ty);
7169
7170 // We are looking for a pattern of, and finding the minimal acceptable cost:
7171 // reduce(mul(ext(A), ext(B))) or
7172 // reduce(mul(A, B)) or
7173 // reduce(ext(A)) or
7174 // reduce(A).
7175 // The basic idea is that we walk down the tree to do that, finding the root
7176 // reduction instruction in InLoopReductionImmediateChains. From there we find
7177 // the pattern of mul/ext and test the cost of the entire pattern vs the cost
7178 // of the components. If the reduction cost is lower then we return it for the
7179 // reduction instruction and 0 for the other instructions in the pattern. If
7180 // it is not we return an invalid cost specifying the orignal cost method
7181 // should be used.
7182 Instruction *RetI = I;
7183 if (match(RetI, m_ZExtOrSExt(m_Value()))) {
7184 if (!RetI->hasOneUser())
7185 return None;
7186 RetI = RetI->user_back();
7187 }
7188 if (match(RetI, m_Mul(m_Value(), m_Value())) &&
7189 RetI->user_back()->getOpcode() == Instruction::Add) {
7190 if (!RetI->hasOneUser())
7191 return None;
7192 RetI = RetI->user_back();
7193 }
7194
7195 // Test if the found instruction is a reduction, and if not return an invalid
7196 // cost specifying the parent to use the original cost modelling.
7197 if (!InLoopReductionImmediateChains.count(RetI))
7198 return None;
7199
7200 // Find the reduction this chain is a part of and calculate the basic cost of
7201 // the reduction on its own.
7202 Instruction *LastChain = InLoopReductionImmediateChains[RetI];
7203 Instruction *ReductionPhi = LastChain;
7204 while (!isa<PHINode>(ReductionPhi))
7205 ReductionPhi = InLoopReductionImmediateChains[ReductionPhi];
7206
7207 const RecurrenceDescriptor &RdxDesc =
7208 Legal->getReductionVars()[cast<PHINode>(ReductionPhi)];
7209
7210 InstructionCost BaseCost = TTI.getArithmeticReductionCost(
7211 RdxDesc.getOpcode(), VectorTy, RdxDesc.getFastMathFlags(), CostKind);
7212
7213 // If we're using ordered reductions then we can just return the base cost
7214 // here, since getArithmeticReductionCost calculates the full ordered
7215 // reduction cost when FP reassociation is not allowed.
7216 if (useOrderedReductions(RdxDesc))
7217 return BaseCost;
7218
7219 // Get the operand that was not the reduction chain and match it to one of the
7220 // patterns, returning the better cost if it is found.
7221 Instruction *RedOp = RetI->getOperand(1) == LastChain
7222 ? dyn_cast<Instruction>(RetI->getOperand(0))
7223 : dyn_cast<Instruction>(RetI->getOperand(1));
7224
7225 VectorTy = VectorType::get(I->getOperand(0)->getType(), VectorTy);
7226
7227 Instruction *Op0, *Op1;
7228 if (RedOp && match(RedOp, m_ZExtOrSExt(m_Value())) &&
7229 !TheLoop->isLoopInvariant(RedOp)) {
7230 // Matched reduce(ext(A))
7231 bool IsUnsigned = isa<ZExtInst>(RedOp);
7232 auto *ExtType = VectorType::get(RedOp->getOperand(0)->getType(), VectorTy);
7233 InstructionCost RedCost = TTI.getExtendedAddReductionCost(
7234 /*IsMLA=*/false, IsUnsigned, RdxDesc.getRecurrenceType(), ExtType,
7235 CostKind);
7236
7237 InstructionCost ExtCost =
7238 TTI.getCastInstrCost(RedOp->getOpcode(), VectorTy, ExtType,
7239 TTI::CastContextHint::None, CostKind, RedOp);
7240 if (RedCost.isValid() && RedCost < BaseCost + ExtCost)
7241 return I == RetI ? RedCost : 0;
7242 } else if (RedOp &&
7243 match(RedOp, m_Mul(m_Instruction(Op0), m_Instruction(Op1)))) {
7244 if (match(Op0, m_ZExtOrSExt(m_Value())) &&
7245 Op0->getOpcode() == Op1->getOpcode() &&
7246 Op0->getOperand(0)->getType() == Op1->getOperand(0)->getType() &&
7247 !TheLoop->isLoopInvariant(Op0) && !TheLoop->isLoopInvariant(Op1)) {
7248 bool IsUnsigned = isa<ZExtInst>(Op0);
7249 auto *ExtType = VectorType::get(Op0->getOperand(0)->getType(), VectorTy);
7250 // Matched reduce(mul(ext, ext))
7251 InstructionCost ExtCost =
7252 TTI.getCastInstrCost(Op0->getOpcode(), VectorTy, ExtType,
7253 TTI::CastContextHint::None, CostKind, Op0);
7254 InstructionCost MulCost =
7255 TTI.getArithmeticInstrCost(Instruction::Mul, VectorTy, CostKind);
7256
7257 InstructionCost RedCost = TTI.getExtendedAddReductionCost(
7258 /*IsMLA=*/true, IsUnsigned, RdxDesc.getRecurrenceType(), ExtType,
7259 CostKind);
7260
7261 if (RedCost.isValid() && RedCost < ExtCost * 2 + MulCost + BaseCost)
7262 return I == RetI ? RedCost : 0;
7263 } else {
7264 // Matched reduce(mul())
7265 InstructionCost MulCost =
7266 TTI.getArithmeticInstrCost(Instruction::Mul, VectorTy, CostKind);
7267
7268 InstructionCost RedCost = TTI.getExtendedAddReductionCost(
7269 /*IsMLA=*/true, true, RdxDesc.getRecurrenceType(), VectorTy,
7270 CostKind);
7271
7272 if (RedCost.isValid() && RedCost < MulCost + BaseCost)
7273 return I == RetI ? RedCost : 0;
7274 }
7275 }
7276
7277 return I == RetI ? Optional<InstructionCost>(BaseCost) : None;
7278}
7279
7280InstructionCost
7281LoopVectorizationCostModel::getMemoryInstructionCost(Instruction *I,
7282 ElementCount VF) {
7283 // Calculate scalar cost only. Vectorization cost should be ready at this
7284 // moment.
7285 if (VF.isScalar()) {
7286 Type *ValTy = getLoadStoreType(I);
7287 const Align Alignment = getLoadStoreAlignment(I);
7288 unsigned AS = getLoadStoreAddressSpace(I);
7289
7290 return TTI.getAddressComputationCost(ValTy) +
7291 TTI.getMemoryOpCost(I->getOpcode(), ValTy, Alignment, AS,
7292 TTI::TCK_RecipThroughput, I);
7293 }
7294 return getWideningCost(I, VF);
7295}
7296
7297LoopVectorizationCostModel::VectorizationCostTy
7298LoopVectorizationCostModel::getInstructionCost(Instruction *I,
7299 ElementCount VF) {
7300 // If we know that this instruction will remain uniform, check the cost of
7301 // the scalar version.
7302 if (isUniformAfterVectorization(I, VF))
7303 VF = ElementCount::getFixed(1);
7304
7305 if (VF.isVector() && isProfitableToScalarize(I, VF))
7306 return VectorizationCostTy(InstsToScalarize[VF][I], false);
7307
7308 // Forced scalars do not have any scalarization overhead.
7309 auto ForcedScalar = ForcedScalars.find(VF);
7310 if (VF.isVector() && ForcedScalar != ForcedScalars.end()) {
7311 auto InstSet = ForcedScalar->second;
7312 if (InstSet.count(I))
7313 return VectorizationCostTy(
7314 (getInstructionCost(I, ElementCount::getFixed(1)).first *
7315 VF.getKnownMinValue()),
7316 false);
7317 }
7318
7319 Type *VectorTy;
7320 InstructionCost C = getInstructionCost(I, VF, VectorTy);
7321
7322 bool TypeNotScalarized =
7323 VF.isVector() && VectorTy->isVectorTy() &&
7324 TTI.getNumberOfParts(VectorTy) < VF.getKnownMinValue();
7325 return VectorizationCostTy(C, TypeNotScalarized);
7326}
7327
7328InstructionCost
7329LoopVectorizationCostModel::getScalarizationOverhead(Instruction *I,
7330 ElementCount VF) const {
7331
7332 // There is no mechanism yet to create a scalable scalarization loop,
7333 // so this is currently Invalid.
7334 if (VF.isScalable())
7335 return InstructionCost::getInvalid();
7336
7337 if (VF.isScalar())
7338 return 0;
7339
7340 InstructionCost Cost = 0;
7341 Type *RetTy = ToVectorTy(I->getType(), VF);
7342 if (!RetTy->isVoidTy() &&
7343 (!isa<LoadInst>(I) || !TTI.supportsEfficientVectorElementLoadStore()))
7344 Cost += TTI.getScalarizationOverhead(
7345 cast<VectorType>(RetTy), APInt::getAllOnesValue(VF.getKnownMinValue()),
7346 true, false);
7347
7348 // Some targets keep addresses scalar.
7349 if (isa<LoadInst>(I) && !TTI.prefersVectorizedAddressing())
7350 return Cost;
7351
7352 // Some targets support efficient element stores.
7353 if (isa<StoreInst>(I) && TTI.supportsEfficientVectorElementLoadStore())
7354 return Cost;
7355
7356 // Collect operands to consider.
7357 CallInst *CI = dyn_cast<CallInst>(I);
7358 Instruction::op_range Ops = CI ? CI->arg_operands() : I->operands();
7359
7360 // Skip operands that do not require extraction/scalarization and do not incur
7361 // any overhead.
7362 SmallVector<Type *> Tys;
7363 for (auto *V : filterExtractingOperands(Ops, VF))
7364 Tys.push_back(MaybeVectorizeType(V->getType(), VF));
7365 return Cost + TTI.getOperandsScalarizationOverhead(
7366 filterExtractingOperands(Ops, VF), Tys);
7367}
7368
7369void LoopVectorizationCostModel::setCostBasedWideningDecision(ElementCount VF) {
7370 if (VF.isScalar())
7371 return;
7372 NumPredStores = 0;
7373 for (BasicBlock *BB : TheLoop->blocks()) {
7374 // For each instruction in the old loop.
7375 for (Instruction &I : *BB) {
7376 Value *Ptr = getLoadStorePointerOperand(&I);
7377 if (!Ptr)
7378 continue;
7379
7380 // TODO: We should generate better code and update the cost model for
7381 // predicated uniform stores. Today they are treated as any other
7382 // predicated store (see added test cases in
7383 // invariant-store-vectorization.ll).
7384 if (isa<StoreInst>(&I) && isScalarWithPredication(&I))
7385 NumPredStores++;
7386
7387 if (Legal->isUniformMemOp(I)) {
7388 // TODO: Avoid replicating loads and stores instead of
7389 // relying on instcombine to remove them.
7390 // Load: Scalar load + broadcast
7391 // Store: Scalar store + isLoopInvariantStoreValue ? 0 : extract
7392 InstructionCost Cost;
7393 if (isa<StoreInst>(&I) && VF.isScalable() &&
7394 isLegalGatherOrScatter(&I)) {
7395 Cost = getGatherScatterCost(&I, VF);
7396 setWideningDecision(&I, VF, CM_GatherScatter, Cost);
7397 } else {
7398 assert((isa<LoadInst>(&I) || !VF.isScalable()) &&((void)0)
7399 "Cannot yet scalarize uniform stores")((void)0);
7400 Cost = getUniformMemOpCost(&I, VF);
7401 setWideningDecision(&I, VF, CM_Scalarize, Cost);
7402 }
7403 continue;
7404 }
7405
7406 // We assume that widening is the best solution when possible.
7407 if (memoryInstructionCanBeWidened(&I, VF)) {
7408 InstructionCost Cost = getConsecutiveMemOpCost(&I, VF);
7409 int ConsecutiveStride =
7410 Legal->isConsecutivePtr(getLoadStorePointerOperand(&I));
7411 assert((ConsecutiveStride == 1 || ConsecutiveStride == -1) &&((void)0)
7412 "Expected consecutive stride.")((void)0);
7413 InstWidening Decision =
7414 ConsecutiveStride == 1 ? CM_Widen : CM_Widen_Reverse;
7415 setWideningDecision(&I, VF, Decision, Cost);
7416 continue;
7417 }
7418
7419 // Choose between Interleaving, Gather/Scatter or Scalarization.
7420 InstructionCost InterleaveCost = InstructionCost::getInvalid();
7421 unsigned NumAccesses = 1;
7422 if (isAccessInterleaved(&I)) {
7423 auto Group = getInterleavedAccessGroup(&I);
7424 assert(Group && "Fail to get an interleaved access group.")((void)0);
7425
7426 // Make one decision for the whole group.
7427 if (getWideningDecision(&I, VF) != CM_Unknown)
7428 continue;
7429
7430 NumAccesses = Group->getNumMembers();
7431 if (interleavedAccessCanBeWidened(&I, VF))
7432 InterleaveCost = getInterleaveGroupCost(&I, VF);
7433 }
7434
7435 InstructionCost GatherScatterCost =
7436 isLegalGatherOrScatter(&I)
7437 ? getGatherScatterCost(&I, VF) * NumAccesses
7438 : InstructionCost::getInvalid();
7439
7440 InstructionCost ScalarizationCost =
7441 getMemInstScalarizationCost(&I, VF) * NumAccesses;
7442
7443 // Choose better solution for the current VF,
7444 // write down this decision and use it during vectorization.
7445 InstructionCost Cost;
7446 InstWidening Decision;
7447 if (InterleaveCost <= GatherScatterCost &&
7448 InterleaveCost < ScalarizationCost) {
7449 Decision = CM_Interleave;
7450 Cost = InterleaveCost;
7451 } else if (GatherScatterCost < ScalarizationCost) {
7452 Decision = CM_GatherScatter;
7453 Cost = GatherScatterCost;
7454 } else {
7455 Decision = CM_Scalarize;
7456 Cost = ScalarizationCost;
7457 }
7458 // If the instructions belongs to an interleave group, the whole group
7459 // receives the same decision. The whole group receives the cost, but
7460 // the cost will actually be assigned to one instruction.
7461 if (auto Group = getInterleavedAccessGroup(&I))
7462 setWideningDecision(Group, VF, Decision, Cost);
7463 else
7464 setWideningDecision(&I, VF, Decision, Cost);
7465 }
7466 }
7467
7468 // Make sure that any load of address and any other address computation
7469 // remains scalar unless there is gather/scatter support. This avoids
7470 // inevitable extracts into address registers, and also has the benefit of
7471 // activating LSR more, since that pass can't optimize vectorized
7472 // addresses.
7473 if (TTI.prefersVectorizedAddressing())
7474 return;
7475
7476 // Start with all scalar pointer uses.
7477 SmallPtrSet<Instruction *, 8> AddrDefs;
7478 for (BasicBlock *BB : TheLoop->blocks())
7479 for (Instruction &I : *BB) {
7480 Instruction *PtrDef =
7481 dyn_cast_or_null<Instruction>(getLoadStorePointerOperand(&I));
7482 if (PtrDef && TheLoop->contains(PtrDef) &&
7483 getWideningDecision(&I, VF) != CM_GatherScatter)
7484 AddrDefs.insert(PtrDef);
7485 }
7486
7487 // Add all instructions used to generate the addresses.
7488 SmallVector<Instruction *, 4> Worklist;
7489 append_range(Worklist, AddrDefs);
7490 while (!Worklist.empty()) {
7491 Instruction *I = Worklist.pop_back_val();
7492 for (auto &Op : I->operands())
7493 if (auto *InstOp = dyn_cast<Instruction>(Op))
7494 if ((InstOp->getParent() == I->getParent()) && !isa<PHINode>(InstOp) &&
7495 AddrDefs.insert(InstOp).second)
7496 Worklist.push_back(InstOp);
7497 }
7498
7499 for (auto *I : AddrDefs) {
7500 if (isa<LoadInst>(I)) {
7501 // Setting the desired widening decision should ideally be handled in
7502 // by cost functions, but since this involves the task of finding out
7503 // if the loaded register is involved in an address computation, it is
7504 // instead changed here when we know this is the case.
7505 InstWidening Decision = getWideningDecision(I, VF);
7506 if (Decision == CM_Widen || Decision == CM_Widen_Reverse)
7507 // Scalarize a widened load of address.
7508 setWideningDecision(
7509 I, VF, CM_Scalarize,
7510 (VF.getKnownMinValue() *
7511 getMemoryInstructionCost(I, ElementCount::getFixed(1))));
7512 else if (auto Group = getInterleavedAccessGroup(I)) {
7513 // Scalarize an interleave group of address loads.
7514 for (unsigned I = 0; I < Group->getFactor(); ++I) {
7515 if (Instruction *Member = Group->getMember(I))
7516 setWideningDecision(
7517 Member, VF, CM_Scalarize,
7518 (VF.getKnownMinValue() *
7519 getMemoryInstructionCost(Member, ElementCount::getFixed(1))));
7520 }
7521 }
7522 } else
7523 // Make sure I gets scalarized and a cost estimate without
7524 // scalarization overhead.
7525 ForcedScalars[VF].insert(I);
7526 }
7527}
7528
7529InstructionCost
7530LoopVectorizationCostModel::getInstructionCost(Instruction *I, ElementCount VF,
7531 Type *&VectorTy) {
7532 Type *RetTy = I->getType();
7533 if (canTruncateToMinimalBitwidth(I, VF))
7534 RetTy = IntegerType::get(RetTy->getContext(), MinBWs[I]);
7535 auto SE = PSE.getSE();
7536 TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
7537
7538 auto hasSingleCopyAfterVectorization = [this](Instruction *I,
7539 ElementCount VF) -> bool {
7540 if (VF.isScalar())
7541 return true;
7542
7543 auto Scalarized = InstsToScalarize.find(VF);
7544 assert(Scalarized != InstsToScalarize.end() &&((void)0)
7545 "VF not yet analyzed for scalarization profitability")((void)0);
7546 return !Scalarized->second.count(I) &&
7547 llvm::all_of(I->users(), [&](User *U) {
7548 auto *UI = cast<Instruction>(U);
7549 return !Scalarized->second.count(UI);
7550 });
7551 };
7552 (void) hasSingleCopyAfterVectorization;
7553
7554 if (isScalarAfterVectorization(I, VF)) {
7555 // With the exception of GEPs and PHIs, after scalarization there should
7556 // only be one copy of the instruction generated in the loop. This is
7557 // because the VF is either 1, or any instructions that need scalarizing
7558 // have already been dealt with by the the time we get here. As a result,
7559 // it means we don't have to multiply the instruction cost by VF.
7560 assert(I->getOpcode() == Instruction::GetElementPtr ||((void)0)
7561 I->getOpcode() == Instruction::PHI ||((void)0)
7562 (I->getOpcode() == Instruction::BitCast &&((void)0)
7563 I->getType()->isPointerTy()) ||((void)0)
7564 hasSingleCopyAfterVectorization(I, VF))((void)0);
7565 VectorTy = RetTy;
7566 } else
7567 VectorTy = ToVectorTy(RetTy, VF);
7568
7569 // TODO: We need to estimate the cost of intrinsic calls.
7570 switch (I->getOpcode()) {
7571 case Instruction::GetElementPtr:
7572 // We mark this instruction as zero-cost because the cost of GEPs in
7573 // vectorized code depends on whether the corresponding memory instruction
7574 // is scalarized or not. Therefore, we handle GEPs with the memory
7575 // instruction cost.
7576 return 0;
7577 case Instruction::Br: {
7578 // In cases of scalarized and predicated instructions, there will be VF
7579 // predicated blocks in the vectorized loop. Each branch around these
7580 // blocks requires also an extract of its vector compare i1 element.
7581 bool ScalarPredicatedBB = false;
7582 BranchInst *BI = cast<BranchInst>(I);
7583 if (VF.isVector() && BI->isConditional() &&
7584 (PredicatedBBsAfterVectorization.count(BI->getSuccessor(0)) ||
7585 PredicatedBBsAfterVectorization.count(BI->getSuccessor(1))))
7586 ScalarPredicatedBB = true;
7587
7588 if (ScalarPredicatedBB) {
7589 // Not possible to scalarize scalable vector with predicated instructions.
7590 if (VF.isScalable())
7591 return InstructionCost::getInvalid();
7592 // Return cost for branches around scalarized and predicated blocks.
7593 auto *Vec_i1Ty =
7594 VectorType::get(IntegerType::getInt1Ty(RetTy->getContext()), VF);
7595 return (
7596 TTI.getScalarizationOverhead(
7597 Vec_i1Ty, APInt::getAllOnesValue(VF.getFixedValue()), false,
7598 true) +
7599 (TTI.getCFInstrCost(Instruction::Br, CostKind) * VF.getFixedValue()));
7600 } else if (I->getParent() == TheLoop->getLoopLatch() || VF.isScalar())
7601 // The back-edge branch will remain, as will all scalar branches.
7602 return TTI.getCFInstrCost(Instruction::Br, CostKind);
7603 else
7604 // This branch will be eliminated by if-conversion.
7605 return 0;
7606 // Note: We currently assume zero cost for an unconditional branch inside
7607 // a predicated block since it will become a fall-through, although we
7608 // may decide in the future to call TTI for all branches.
7609 }
7610 case Instruction::PHI: {
7611 auto *Phi = cast<PHINode>(I);
7612
7613 // First-order recurrences are replaced by vector shuffles inside the loop.
7614 // NOTE: Don't use ToVectorTy as SK_ExtractSubvector expects a vector type.
7615 if (VF.isVector() && Legal->isFirstOrderRecurrence(Phi))
7616 return TTI.getShuffleCost(
7617 TargetTransformInfo::SK_ExtractSubvector, cast<VectorType>(VectorTy),
7618 None, VF.getKnownMinValue() - 1, FixedVectorType::get(RetTy, 1));
7619
7620 // Phi nodes in non-header blocks (not inductions, reductions, etc.) are
7621 // converted into select instructions. We require N - 1 selects per phi
7622 // node, where N is the number of incoming values.
7623 if (VF.isVector() && Phi->getParent() != TheLoop->getHeader())
7624 return (Phi->getNumIncomingValues() - 1) *
7625 TTI.getCmpSelInstrCost(
7626 Instruction::Select, ToVectorTy(Phi->getType(), VF),
7627 ToVectorTy(Type::getInt1Ty(Phi->getContext()), VF),
7628 CmpInst::BAD_ICMP_PREDICATE, CostKind);
7629
7630 return TTI.getCFInstrCost(Instruction::PHI, CostKind);
7631 }
7632 case Instruction::UDiv:
7633 case Instruction::SDiv:
7634 case Instruction::URem:
7635 case Instruction::SRem:
7636 // If we have a predicated instruction, it may not be executed for each
7637 // vector lane. Get the scalarization cost and scale this amount by the
7638 // probability of executing the predicated block. If the instruction is not
7639 // predicated, we fall through to the next case.
7640 if (VF.isVector() && isScalarWithPredication(I)) {
7641 InstructionCost Cost = 0;
7642
7643 // These instructions have a non-void type, so account for the phi nodes
7644 // that we will create. This cost is likely to be zero. The phi node
7645 // cost, if any, should be scaled by the block probability because it
7646 // models a copy at the end of each predicated block.
7647 Cost += VF.getKnownMinValue() *
7648 TTI.getCFInstrCost(Instruction::PHI, CostKind);
7649
7650 // The cost of the non-predicated instruction.
7651 Cost += VF.getKnownMinValue() *
7652 TTI.getArithmeticInstrCost(I->getOpcode(), RetTy, CostKind);
7653
7654 // The cost of insertelement and extractelement instructions needed for
7655 // scalarization.
7656 Cost += getScalarizationOverhead(I, VF);
7657
7658 // Scale the cost by the probability of executing the predicated blocks.
7659 // This assumes the predicated block for each vector lane is equally
7660 // likely.
7661 return Cost / getReciprocalPredBlockProb();
7662 }
7663 LLVM_FALLTHROUGH[[gnu::fallthrough]];
7664 case Instruction::Add:
7665 case Instruction::FAdd:
7666 case Instruction::Sub:
7667 case Instruction::FSub:
7668 case Instruction::Mul:
7669 case Instruction::FMul:
7670 case Instruction::FDiv:
7671 case Instruction::FRem:
7672 case Instruction::Shl:
7673 case Instruction::LShr:
7674 case Instruction::AShr:
7675 case Instruction::And:
7676 case Instruction::Or:
7677 case Instruction::Xor: {
7678 // Since we will replace the stride by 1 the multiplication should go away.
7679 if (I->getOpcode() == Instruction::Mul && isStrideMul(I, Legal))
7680 return 0;
7681
7682 // Detect reduction patterns
7683 if (auto RedCost = getReductionPatternCost(I, VF, VectorTy, CostKind))
7684 return *RedCost;
7685
7686 // Certain instructions can be cheaper to vectorize if they have a constant
7687 // second vector operand. One example of this are shifts on x86.
7688 Value *Op2 = I->getOperand(1);
7689 TargetTransformInfo::OperandValueProperties Op2VP;
7690 TargetTransformInfo::OperandValueKind Op2VK =
7691 TTI.getOperandInfo(Op2, Op2VP);
7692 if (Op2VK == TargetTransformInfo::OK_AnyValue && Legal->isUniform(Op2))
7693 Op2VK = TargetTransformInfo::OK_UniformValue;
7694
7695 SmallVector<const Value *, 4> Operands(I->operand_values());
7696 return TTI.getArithmeticInstrCost(
7697 I->getOpcode(), VectorTy, CostKind, TargetTransformInfo::OK_AnyValue,
7698 Op2VK, TargetTransformInfo::OP_None, Op2VP, Operands, I);
7699 }
7700 case Instruction::FNeg: {
7701 return TTI.getArithmeticInstrCost(
7702 I->getOpcode(), VectorTy, CostKind, TargetTransformInfo::OK_AnyValue,
7703 TargetTransformInfo::OK_AnyValue, TargetTransformInfo::OP_None,
7704 TargetTransformInfo::OP_None, I->getOperand(0), I);
7705 }
7706 case Instruction::Select: {
7707 SelectInst *SI = cast<SelectInst>(I);
7708 const SCEV *CondSCEV = SE->getSCEV(SI->getCondition());
7709 bool ScalarCond = (SE->isLoopInvariant(CondSCEV, TheLoop));
7710
7711 const Value *Op0, *Op1;
7712 using namespace llvm::PatternMatch;
7713 if (!ScalarCond && (match(I, m_LogicalAnd(m_Value(Op0), m_Value(Op1))) ||
7714 match(I, m_LogicalOr(m_Value(Op0), m_Value(Op1))))) {
7715 // select x, y, false --> x & y
7716 // select x, true, y --> x | y
7717 TTI::OperandValueProperties Op1VP = TTI::OP_None;
7718 TTI::OperandValueProperties Op2VP = TTI::OP_None;
7719 TTI::OperandValueKind Op1VK = TTI::getOperandInfo(Op0, Op1VP);
7720 TTI::OperandValueKind Op2VK = TTI::getOperandInfo(Op1, Op2VP);
7721 assert(Op0->getType()->getScalarSizeInBits() == 1 &&((void)0)
7722 Op1->getType()->getScalarSizeInBits() == 1)((void)0);
7723
7724 SmallVector<const Value *, 2> Operands{Op0, Op1};
7725 return TTI.getArithmeticInstrCost(
7726 match(I, m_LogicalOr()) ? Instruction::Or : Instruction::And, VectorTy,
7727 CostKind, Op1VK, Op2VK, Op1VP, Op2VP, Operands, I);
7728 }
7729
7730 Type *CondTy = SI->getCondition()->getType();
7731 if (!ScalarCond)
7732 CondTy = VectorType::get(CondTy, VF);
7733 return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy, CondTy,
7734 CmpInst::BAD_ICMP_PREDICATE, CostKind, I);
7735 }
7736 case Instruction::ICmp:
7737 case Instruction::FCmp: {
7738 Type *ValTy = I->getOperand(0)->getType();
7739 Instruction *Op0AsInstruction = dyn_cast<Instruction>(I->getOperand(0));
7740 if (canTruncateToMinimalBitwidth(Op0AsInstruction, VF))
7741 ValTy = IntegerType::get(ValTy->getContext(), MinBWs[Op0AsInstruction]);
7742 VectorTy = ToVectorTy(ValTy, VF);
7743 return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy, nullptr,
7744 CmpInst::BAD_ICMP_PREDICATE, CostKind, I);
7745 }
7746 case Instruction::Store:
7747 case Instruction::Load: {
7748 ElementCount Width = VF;
7749 if (Width.isVector()) {
7750 InstWidening Decision = getWideningDecision(I, Width);
7751 assert(Decision != CM_Unknown &&((void)0)
7752 "CM decision should be taken at this point")((void)0);
7753 if (Decision == CM_Scalarize)
7754 Width = ElementCount::getFixed(1);
7755 }
7756 VectorTy = ToVectorTy(getLoadStoreType(I), Width);
7757 return getMemoryInstructionCost(I, VF);
7758 }
7759 case Instruction::BitCast:
7760 if (I->getType()->isPointerTy())
7761 return 0;
7762 LLVM_FALLTHROUGH[[gnu::fallthrough]];
7763 case Instruction::ZExt:
7764 case Instruction::SExt:
7765 case Instruction::FPToUI:
7766 case Instruction::FPToSI:
7767 case Instruction::FPExt:
7768 case Instruction::PtrToInt:
7769 case Instruction::IntToPtr:
7770 case Instruction::SIToFP:
7771 case Instruction::UIToFP:
7772 case Instruction::Trunc:
7773 case Instruction::FPTrunc: {
7774 // Computes the CastContextHint from a Load/Store instruction.
7775 auto ComputeCCH = [&](Instruction *I) -> TTI::CastContextHint {
7776 assert((isa<LoadInst>(I) || isa<StoreInst>(I)) &&((void)0)
7777 "Expected a load or a store!")((void)0);
7778
7779 if (VF.isScalar() || !TheLoop->contains(I))
7780 return TTI::CastContextHint::Normal;
7781
7782 switch (getWideningDecision(I, VF)) {
7783 case LoopVectorizationCostModel::CM_GatherScatter:
7784 return TTI::CastContextHint::GatherScatter;
7785 case LoopVectorizationCostModel::CM_Interleave:
7786 return TTI::CastContextHint::Interleave;
7787 case LoopVectorizationCostModel::CM_Scalarize:
7788 case LoopVectorizationCostModel::CM_Widen:
7789 return Legal->isMaskRequired(I) ? TTI::CastContextHint::Masked
7790 : TTI::CastContextHint::Normal;
7791 case LoopVectorizationCostModel::CM_Widen_Reverse:
7792 return TTI::CastContextHint::Reversed;
7793 case LoopVectorizationCostModel::CM_Unknown:
7794 llvm_unreachable("Instr did not go through cost modelling?")__builtin_unreachable();
7795 }
7796
7797 llvm_unreachable("Unhandled case!")__builtin_unreachable();
7798 };
7799
7800 unsigned Opcode = I->getOpcode();
7801 TTI::CastContextHint CCH = TTI::CastContextHint::None;
7802 // For Trunc, the context is the only user, which must be a StoreInst.
7803 if (Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) {
7804 if (I->hasOneUse())
7805 if (StoreInst *Store = dyn_cast<StoreInst>(*I->user_begin()))
7806 CCH = ComputeCCH(Store);
7807 }
7808 // For Z/Sext, the context is the operand, which must be a LoadInst.
7809 else if (Opcode == Instruction::ZExt || Opcode == Instruction::SExt ||
7810 Opcode == Instruction::FPExt) {
7811 if (LoadInst *Load = dyn_cast<LoadInst>(I->getOperand(0)))
7812 CCH = ComputeCCH(Load);
7813 }
7814
7815 // We optimize the truncation of induction variables having constant
7816 // integer steps. The cost of these truncations is the same as the scalar
7817 // operation.
7818 if (isOptimizableIVTruncate(I, VF)) {
7819 auto *Trunc = cast<TruncInst>(I);
7820 return TTI.getCastInstrCost(Instruction::Trunc, Trunc->getDestTy(),
7821 Trunc->getSrcTy(), CCH, CostKind, Trunc);
7822 }
7823
7824 // Detect reduction patterns
7825 if (auto RedCost = getReductionPatternCost(I, VF, VectorTy, CostKind))
7826 return *RedCost;
7827
7828 Type *SrcScalarTy = I->getOperand(0)->getType();
7829 Type *SrcVecTy =
7830 VectorTy->isVectorTy() ? ToVectorTy(SrcScalarTy, VF) : SrcScalarTy;
7831 if (canTruncateToMinimalBitwidth(I, VF)) {
7832 // This cast is going to be shrunk. This may remove the cast or it might
7833 // turn it into slightly different cast. For example, if MinBW == 16,
7834 // "zext i8 %1 to i32" becomes "zext i8 %1 to i16".
7835 //
7836 // Calculate the modified src and dest types.
7837 Type *MinVecTy = VectorTy;
7838 if (Opcode == Instruction::Trunc) {
7839 SrcVecTy = smallestIntegerVectorType(SrcVecTy, MinVecTy);
7840 VectorTy =
7841 largestIntegerVectorType(ToVectorTy(I->getType(), VF), MinVecTy);
7842 } else if (Opcode == Instruction::ZExt || Opcode == Instruction::SExt) {
7843 SrcVecTy = largestIntegerVectorType(SrcVecTy, MinVecTy);
7844 VectorTy =
7845 smallestIntegerVectorType(ToVectorTy(I->getType(), VF), MinVecTy);
7846 }
7847 }
7848
7849 return TTI.getCastInstrCost(Opcode, VectorTy, SrcVecTy, CCH, CostKind, I);
7850 }
7851 case Instruction::Call: {
7852 bool NeedToScalarize;
7853 CallInst *CI = cast<CallInst>(I);
7854 InstructionCost CallCost = getVectorCallCost(CI, VF, NeedToScalarize);
7855 if (getVectorIntrinsicIDForCall(CI, TLI)) {
7856 InstructionCost IntrinsicCost = getVectorIntrinsicCost(CI, VF);
7857 return std::min(CallCost, IntrinsicCost);
7858 }
7859 return CallCost;
7860 }
7861 case Instruction::ExtractValue:
7862 return TTI.getInstructionCost(I, TTI::TCK_RecipThroughput);
7863 case Instruction::Alloca:
7864 // We cannot easily widen alloca to a scalable alloca, as
7865 // the result would need to be a vector of pointers.
7866 if (VF.isScalable())
7867 return InstructionCost::getInvalid();
7868 LLVM_FALLTHROUGH[[gnu::fallthrough]];
7869 default:
7870 // This opcode is unknown. Assume that it is the same as 'mul'.
7871 return TTI.getArithmeticInstrCost(Instruction::Mul, VectorTy, CostKind);
7872 } // end of switch.
7873}
7874
7875char LoopVectorize::ID = 0;
7876
7877static const char lv_name[] = "Loop Vectorization";
7878
7879INITIALIZE_PASS_BEGIN(LoopVectorize, LV_NAME, lv_name, false, false)static void *initializeLoopVectorizePassOnce(PassRegistry &
Registry) {
7880INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry);
7881INITIALIZE_PASS_DEPENDENCY(BasicAAWrapperPass)initializeBasicAAWrapperPassPass(Registry);
7882INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)initializeAAResultsWrapperPassPass(Registry);
7883INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)initializeGlobalsAAWrapperPassPass(Registry);
7884INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
7885INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)initializeBlockFrequencyInfoWrapperPassPass(Registry);
7886INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
7887INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)initializeScalarEvolutionWrapperPassPass(Registry);
7888INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
7889INITIALIZE_PASS_DEPENDENCY(LoopAccessLegacyAnalysis)initializeLoopAccessLegacyAnalysisPass(Registry);
7890INITIALIZE_PASS_DEPENDENCY(DemandedBitsWrapperPass)initializeDemandedBitsWrapperPassPass(Registry);
7891INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)initializeOptimizationRemarkEmitterWrapperPassPass(Registry);
7892INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);
7893INITIALIZE_PASS_DEPENDENCY(InjectTLIMappingsLegacy)initializeInjectTLIMappingsLegacyPass(Registry);
7894INITIALIZE_PASS_END(LoopVectorize, LV_NAME, lv_name, false, false)PassInfo *PI = new PassInfo( lv_name, "loop-vectorize", &
LoopVectorize::ID, PassInfo::NormalCtor_t(callDefaultCtor<
LoopVectorize>), false, false); Registry.registerPass(*PI,
true); return PI; } static llvm::once_flag InitializeLoopVectorizePassFlag
; void llvm::initializeLoopVectorizePass(PassRegistry &Registry
) { llvm::call_once(InitializeLoopVectorizePassFlag, initializeLoopVectorizePassOnce
, std::ref(Registry)); }
7895
7896namespace llvm {
7897
7898Pass *createLoopVectorizePass() { return new LoopVectorize(); }
7899
7900Pass *createLoopVectorizePass(bool InterleaveOnlyWhenForced,
7901 bool VectorizeOnlyWhenForced) {
7902 return new LoopVectorize(InterleaveOnlyWhenForced, VectorizeOnlyWhenForced);
7903}
7904
7905} // end namespace llvm
7906
7907bool LoopVectorizationCostModel::isConsecutiveLoadOrStore(Instruction *Inst) {
7908 // Check if the pointer operand of a load or store instruction is
7909 // consecutive.
7910 if (auto *Ptr = getLoadStorePointerOperand(Inst))
7911 return Legal->isConsecutivePtr(Ptr);
7912 return false;
7913}
7914
7915void LoopVectorizationCostModel::collectValuesToIgnore() {
7916 // Ignore ephemeral values.
7917 CodeMetrics::collectEphemeralValues(TheLoop, AC, ValuesToIgnore);
7918
7919 // Ignore type-promoting instructions we identified during reduction
7920 // detection.
7921 for (auto &Reduction : Legal->getReductionVars()) {
7922 RecurrenceDescriptor &RedDes = Reduction.second;
7923 const SmallPtrSetImpl<Instruction *> &Casts = RedDes.getCastInsts();
7924 VecValuesToIgnore.insert(Casts.begin(), Casts.end());
7925 }
7926 // Ignore type-casting instructions we identified during induction
7927 // detection.
7928 for (auto &Induction : Legal->getInductionVars()) {
7929 InductionDescriptor &IndDes = Induction.second;
7930 const SmallVectorImpl<Instruction *> &Casts = IndDes.getCastInsts();
7931 VecValuesToIgnore.insert(Casts.begin(), Casts.end());
7932 }
7933}
7934
7935void LoopVectorizationCostModel::collectInLoopReductions() {
7936 for (auto &Reduction : Legal->getReductionVars()) {
7937 PHINode *Phi = Reduction.first;
7938 RecurrenceDescriptor &RdxDesc = Reduction.second;
7939
7940 // We don't collect reductions that are type promoted (yet).
7941 if (RdxDesc.getRecurrenceType() != Phi->getType())
7942 continue;
7943
7944 // If the target would prefer this reduction to happen "in-loop", then we
7945 // want to record it as such.
7946 unsigned Opcode = RdxDesc.getOpcode();
7947 if (!PreferInLoopReductions && !useOrderedReductions(RdxDesc) &&
7948 !TTI.preferInLoopReduction(Opcode, Phi->getType(),
7949 TargetTransformInfo::ReductionFlags()))
7950 continue;
7951
7952 // Check that we can correctly put the reductions into the loop, by
7953 // finding the chain of operations that leads from the phi to the loop
7954 // exit value.
7955 SmallVector<Instruction *, 4> ReductionOperations =
7956 RdxDesc.getReductionOpChain(Phi, TheLoop);
7957 bool InLoop = !ReductionOperations.empty();
7958 if (InLoop) {
7959 InLoopReductionChains[Phi] = ReductionOperations;
7960 // Add the elements to InLoopReductionImmediateChains for cost modelling.
7961 Instruction *LastChain = Phi;
7962 for (auto *I : ReductionOperations) {
7963 InLoopReductionImmediateChains[I] = LastChain;
7964 LastChain = I;
7965 }
7966 }
7967 LLVM_DEBUG(dbgs() << "LV: Using " << (InLoop ? "inloop" : "out of loop")do { } while (false)
7968 << " reduction for phi: " << *Phi << "\n")do { } while (false);
7969 }
7970}
7971
7972// TODO: we could return a pair of values that specify the max VF and
7973// min VF, to be used in `buildVPlans(MinVF, MaxVF)` instead of
7974// `buildVPlans(VF, VF)`. We cannot do it because VPLAN at the moment
7975// doesn't have a cost model that can choose which plan to execute if
7976// more than one is generated.
7977static unsigned determineVPlanVF(const unsigned WidestVectorRegBits,
7978 LoopVectorizationCostModel &CM) {
7979 unsigned WidestType;
7980 std::tie(std::ignore, WidestType) = CM.getSmallestAndWidestTypes();
7981 return WidestVectorRegBits / WidestType;
7982}
7983
7984VectorizationFactor
7985LoopVectorizationPlanner::planInVPlanNativePath(ElementCount UserVF) {
7986 assert(!UserVF.isScalable() && "scalable vectors not yet supported")((void)0);
7987 ElementCount VF = UserVF;
7988 // Outer loop handling: They may require CFG and instruction level
7989 // transformations before even evaluating whether vectorization is profitable.
7990 // Since we cannot modify the incoming IR, we need to build VPlan upfront in
7991 // the vectorization pipeline.
7992 if (!OrigLoop->isInnermost()) {
7993 // If the user doesn't provide a vectorization factor, determine a
7994 // reasonable one.
7995 if (UserVF.isZero()) {
7996 VF = ElementCount::getFixed(determineVPlanVF(
7997 TTI->getRegisterBitWidth(TargetTransformInfo::RGK_FixedWidthVector)
7998 .getFixedSize(),
7999 CM));
8000 LLVM_DEBUG(dbgs() << "LV: VPlan computed VF " << VF << ".\n")do { } while (false);
8001
8002 // Make sure we have a VF > 1 for stress testing.
8003 if (VPlanBuildStressTest && (VF.isScalar() || VF.isZero())) {
8004 LLVM_DEBUG(dbgs() << "LV: VPlan stress testing: "do { } while (false)
8005 << "overriding computed VF.\n")do { } while (false);
8006 VF = ElementCount::getFixed(4);
8007 }
8008 }
8009 assert(EnableVPlanNativePath && "VPlan-native path is not enabled.")((void)0);
8010 assert(isPowerOf2_32(VF.getKnownMinValue()) &&((void)0)
8011 "VF needs to be a power of two")((void)0);
8012 LLVM_DEBUG(dbgs() << "LV: Using " << (!UserVF.isZero() ? "user " : "")do { } while (false)
8013 << "VF " << VF << " to build VPlans.\n")do { } while (false);
8014 buildVPlans(VF, VF);
8015
8016 // For VPlan build stress testing, we bail out after VPlan construction.
8017 if (VPlanBuildStressTest)
8018 return VectorizationFactor::Disabled();
8019
8020 return {VF, 0 /*Cost*/};
8021 }
8022
8023 LLVM_DEBUG(do { } while (false)
8024 dbgs() << "LV: Not vectorizing. Inner loops aren't supported in the "do { } while (false)
8025 "VPlan-native path.\n")do { } while (false);
8026 return VectorizationFactor::Disabled();
8027}
8028
8029Optional<VectorizationFactor>
8030LoopVectorizationPlanner::plan(ElementCount UserVF, unsigned UserIC) {
8031 assert(OrigLoop->isInnermost() && "Inner loop expected.")((void)0);
8032 FixedScalableVFPair MaxFactors = CM.computeMaxVF(UserVF, UserIC);
8033 if (!MaxFactors) // Cases that should not to be vectorized nor interleaved.
8034 return None;
8035
8036 // Invalidate interleave groups if all blocks of loop will be predicated.
8037 if (CM.blockNeedsPredication(OrigLoop->getHeader()) &&
8038 !useMaskedInterleavedAccesses(*TTI)) {
8039 LLVM_DEBUG(do { } while (false)
8040 dbgs()do { } while (false)
8041 << "LV: Invalidate all interleaved groups due to fold-tail by masking "do { } while (false)
8042 "which requires masked-interleaved support.\n")do { } while (false);
8043 if (CM.InterleaveInfo.invalidateGroups())
8044 // Invalidating interleave groups also requires invalidating all decisions
8045 // based on them, which includes widening decisions and uniform and scalar
8046 // values.
8047 CM.invalidateCostModelingDecisions();
8048 }
8049
8050 ElementCount MaxUserVF =
8051 UserVF.isScalable() ? MaxFactors.ScalableVF : MaxFactors.FixedVF;
8052 bool UserVFIsLegal = ElementCount::isKnownLE(UserVF, MaxUserVF);
8053 if (!UserVF.isZero() && UserVFIsLegal) {
8054 assert(isPowerOf2_32(UserVF.getKnownMinValue()) &&((void)0)
8055 "VF needs to be a power of two")((void)0);
8056 // Collect the instructions (and their associated costs) that will be more
8057 // profitable to scalarize.
8058 if (CM.selectUserVectorizationFactor(UserVF)) {
8059 LLVM_DEBUG(dbgs() << "LV: Using user VF " << UserVF << ".\n")do { } while (false);
8060 CM.collectInLoopReductions();
8061 buildVPlansWithVPRecipes(UserVF, UserVF);
8062 LLVM_DEBUG(printPlans(dbgs()))do { } while (false);
8063 return {{UserVF, 0}};
8064 } else
8065 reportVectorizationInfo("UserVF ignored because of invalid costs.",
8066 "InvalidCost", ORE, OrigLoop);
8067 }
8068
8069 // Populate the set of Vectorization Factor Candidates.
8070 ElementCountSet VFCandidates;
8071 for (auto VF = ElementCount::getFixed(1);
8072 ElementCount::isKnownLE(VF, MaxFactors.FixedVF); VF *= 2)
8073 VFCandidates.insert(VF);
8074 for (auto VF = ElementCount::getScalable(1);
8075 ElementCount::isKnownLE(VF, MaxFactors.ScalableVF); VF *= 2)
8076 VFCandidates.insert(VF);
8077
8078 for (const auto &VF : VFCandidates) {
8079 // Collect Uniform and Scalar instructions after vectorization with VF.
8080 CM.collectUniformsAndScalars(VF);
8081
8082 // Collect the instructions (and their associated costs) that will be more
8083 // profitable to scalarize.
8084 if (VF.isVector())
8085 CM.collectInstsToScalarize(VF);
8086 }
8087
8088 CM.collectInLoopReductions();
8089 buildVPlansWithVPRecipes(ElementCount::getFixed(1), MaxFactors.FixedVF);
8090 buildVPlansWithVPRecipes(ElementCount::getScalable(1), MaxFactors.ScalableVF);
8091
8092 LLVM_DEBUG(printPlans(dbgs()))do { } while (false);
8093 if (!MaxFactors.hasVector())
8094 return VectorizationFactor::Disabled();
8095
8096 // Select the optimal vectorization factor.
8097 auto SelectedVF = CM.selectVectorizationFactor(VFCandidates);
8098
8099 // Check if it is profitable to vectorize with runtime checks.
8100 unsigned NumRuntimePointerChecks = Requirements.getNumRuntimePointerChecks();
8101 if (SelectedVF.Width.getKnownMinValue() > 1 && NumRuntimePointerChecks) {
8102 bool PragmaThresholdReached =
8103 NumRuntimePointerChecks > PragmaVectorizeMemoryCheckThreshold;
8104 bool ThresholdReached =
8105 NumRuntimePointerChecks > VectorizerParams::RuntimeMemoryCheckThreshold;
8106 if ((ThresholdReached && !Hints.allowReordering()) ||
8107 PragmaThresholdReached) {
8108 ORE->emit([&]() {
8109 return OptimizationRemarkAnalysisAliasing(
8110 DEBUG_TYPE"loop-vectorize", "CantReorderMemOps", OrigLoop->getStartLoc(),
8111 OrigLoop->getHeader())
8112 << "loop not vectorized: cannot prove it is safe to reorder "
8113 "memory operations";
8114 });
8115 LLVM_DEBUG(dbgs() << "LV: Too many memory checks needed.\n")do { } while (false);
8116 Hints.emitRemarkWithHints();
8117 return VectorizationFactor::Disabled();
8118 }
8119 }
8120 return SelectedVF;
8121}
8122
8123void LoopVectorizationPlanner::setBestPlan(ElementCount VF, unsigned UF) {
8124 LLVM_DEBUG(dbgs() << "Setting best plan to VF=" << VF << ", UF=" << UFdo { } while (false)
8125 << '\n')do { } while (false);
8126 BestVF = VF;
8127 BestUF = UF;
8128
8129 erase_if(VPlans, [VF](const VPlanPtr &Plan) {
8130 return !Plan->hasVF(VF);
8131 });
8132 assert(VPlans.size() == 1 && "Best VF has not a single VPlan.")((void)0);
8133}
8134
8135void LoopVectorizationPlanner::executePlan(InnerLoopVectorizer &ILV,
8136 DominatorTree *DT) {
8137 // Perform the actual loop transformation.
8138
8139 // 1. Create a new empty loop. Unlink the old loop and connect the new one.
8140 assert(BestVF.hasValue() && "Vectorization Factor is missing")((void)0);
8141 assert(VPlans.size() == 1 && "Not a single VPlan to execute.")((void)0);
8142
8143 VPTransformState State{
8144 *BestVF, BestUF, LI, DT, ILV.Builder, &ILV, VPlans.front().get()};
8145 State.CFG.PrevBB = ILV.createVectorizedLoopSkeleton();
8146 State.TripCount = ILV.getOrCreateTripCount(nullptr);
16
Passing null pointer value via 1st parameter 'L'
17
Calling 'InnerLoopVectorizer::getOrCreateTripCount'
8147 State.CanonicalIV = ILV.Induction;
8148
8149 ILV.printDebugTracesAtStart();
8150
8151 //===------------------------------------------------===//
8152 //
8153 // Notice: any optimization or new instruction that go
8154 // into the code below should also be implemented in
8155 // the cost-model.
8156 //
8157 //===------------------------------------------------===//
8158
8159 // 2. Copy and widen instructions from the old loop into the new loop.
8160 VPlans.front()->execute(&State);
8161
8162 // 3. Fix the vectorized code: take care of header phi's, live-outs,
8163 // predication, updating analyses.
8164 ILV.fixVectorizedLoop(State);
8165
8166 ILV.printDebugTracesAtEnd();
8167}
8168
8169#if !defined(NDEBUG1) || defined(LLVM_ENABLE_DUMP)
8170void LoopVectorizationPlanner::printPlans(raw_ostream &O) {
8171 for (const auto &Plan : VPlans)
8172 if (PrintVPlansInDotFormat)
8173 Plan->printDOT(O);
8174 else
8175 Plan->print(O);
8176}
8177#endif
8178
8179void LoopVectorizationPlanner::collectTriviallyDeadInstructions(
8180 SmallPtrSetImpl<Instruction *> &DeadInstructions) {
8181
8182 // We create new control-flow for the vectorized loop, so the original exit
8183 // conditions will be dead after vectorization if it's only used by the
8184 // terminator
8185 SmallVector<BasicBlock*> ExitingBlocks;
8186 OrigLoop->getExitingBlocks(ExitingBlocks);
8187 for (auto *BB : ExitingBlocks) {
8188 auto *Cmp = dyn_cast<Instruction>(BB->getTerminator()->getOperand(0));
8189 if (!Cmp || !Cmp->hasOneUse())
8190 continue;
8191
8192 // TODO: we should introduce a getUniqueExitingBlocks on Loop
8193 if (!DeadInstructions.insert(Cmp).second)
8194 continue;
8195
8196 // The operands of the icmp is often a dead trunc, used by IndUpdate.
8197 // TODO: can recurse through operands in general
8198 for (Value *Op : Cmp->operands()) {
8199 if (isa<TruncInst>(Op) && Op->hasOneUse())
8200 DeadInstructions.insert(cast<Instruction>(Op));
8201 }
8202 }
8203
8204 // We create new "steps" for induction variable updates to which the original
8205 // induction variables map. An original update instruction will be dead if
8206 // all its users except the induction variable are dead.
8207 auto *Latch = OrigLoop->getLoopLatch();
8208 for (auto &Induction : Legal->getInductionVars()) {
8209 PHINode *Ind = Induction.first;
8210 auto *IndUpdate = cast<Instruction>(Ind->getIncomingValueForBlock(Latch));
8211
8212 // If the tail is to be folded by masking, the primary induction variable,
8213 // if exists, isn't dead: it will be used for masking. Don't kill it.
8214 if (CM.foldTailByMasking() && IndUpdate == Legal->getPrimaryInduction())
8215 continue;
8216
8217 if (llvm::all_of(IndUpdate->users(), [&](User *U) -> bool {
8218 return U == Ind || DeadInstructions.count(cast<Instruction>(U));
8219 }))
8220 DeadInstructions.insert(IndUpdate);
8221
8222 // We record as "Dead" also the type-casting instructions we had identified
8223 // during induction analysis. We don't need any handling for them in the
8224 // vectorized loop because we have proven that, under a proper runtime
8225 // test guarding the vectorized loop, the value of the phi, and the casted
8226 // value of the phi, are the same. The last instruction in this casting chain
8227 // will get its scalar/vector/widened def from the scalar/vector/widened def
8228 // of the respective phi node. Any other casts in the induction def-use chain
8229 // have no other uses outside the phi update chain, and will be ignored.
8230 InductionDescriptor &IndDes = Induction.second;
8231 const SmallVectorImpl<Instruction *> &Casts = IndDes.getCastInsts();
8232 DeadInstructions.insert(Casts.begin(), Casts.end());
8233 }
8234}
8235
8236Value *InnerLoopUnroller::reverseVector(Value *Vec) { return Vec; }
8237
8238Value *InnerLoopUnroller::getBroadcastInstrs(Value *V) { return V; }
8239
8240Value *InnerLoopUnroller::getStepVector(Value *Val, int StartIdx, Value *Step,
8241 Instruction::BinaryOps BinOp) {
8242 // When unrolling and the VF is 1, we only need to add a simple scalar.
8243 Type *Ty = Val->getType();
8244 assert(!Ty->isVectorTy() && "Val must be a scalar")((void)0);
8245
8246 if (Ty->isFloatingPointTy()) {
8247 Constant *C = ConstantFP::get(Ty, (double)StartIdx);
8248
8249 // Floating-point operations inherit FMF via the builder's flags.
8250 Value *MulOp = Builder.CreateFMul(C, Step);
8251 return Builder.CreateBinOp(BinOp, Val, MulOp);
8252 }
8253 Constant *C = ConstantInt::get(Ty, StartIdx);
8254 return Builder.CreateAdd(Val, Builder.CreateMul(C, Step), "induction");
8255}
8256
8257static void AddRuntimeUnrollDisableMetaData(Loop *L) {
8258 SmallVector<Metadata *, 4> MDs;
8259 // Reserve first location for self reference to the LoopID metadata node.
8260 MDs.push_back(nullptr);
8261 bool IsUnrollMetadata = false;
8262 MDNode *LoopID = L->getLoopID();
8263 if (LoopID) {
8264 // First find existing loop unrolling disable metadata.
8265 for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
8266 auto *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
8267 if (MD) {
8268 const auto *S = dyn_cast<MDString>(MD->getOperand(0));
8269 IsUnrollMetadata =
8270 S && S->getString().startswith("llvm.loop.unroll.disable");
8271 }
8272 MDs.push_back(LoopID->getOperand(i));
8273 }
8274 }
8275
8276 if (!IsUnrollMetadata) {
8277 // Add runtime unroll disable metadata.
8278 LLVMContext &Context = L->getHeader()->getContext();
8279 SmallVector<Metadata *, 1> DisableOperands;
8280 DisableOperands.push_back(
8281 MDString::get(Context, "llvm.loop.unroll.runtime.disable"));
8282 MDNode *DisableNode = MDNode::get(Context, DisableOperands);
8283 MDs.push_back(DisableNode);
8284 MDNode *NewLoopID = MDNode::get(Context, MDs);
8285 // Set operand 0 to refer to the loop id itself.
8286 NewLoopID->replaceOperandWith(0, NewLoopID);
8287 L->setLoopID(NewLoopID);
8288 }
8289}
8290
8291//===--------------------------------------------------------------------===//
8292// EpilogueVectorizerMainLoop
8293//===--------------------------------------------------------------------===//
8294
8295/// This function is partially responsible for generating the control flow
8296/// depicted in https://llvm.org/docs/Vectorizers.html#epilogue-vectorization.
8297BasicBlock *EpilogueVectorizerMainLoop::createEpilogueVectorizedLoopSkeleton() {
8298 MDNode *OrigLoopID = OrigLoop->getLoopID();
8299 Loop *Lp = createVectorLoopSkeleton("");
8300
8301 // Generate the code to check the minimum iteration count of the vector
8302 // epilogue (see below).
8303 EPI.EpilogueIterationCountCheck =
8304 emitMinimumIterationCountCheck(Lp, LoopScalarPreHeader, true);
8305 EPI.EpilogueIterationCountCheck->setName("iter.check");
8306
8307 // Generate the code to check any assumptions that we've made for SCEV
8308 // expressions.
8309 EPI.SCEVSafetyCheck = emitSCEVChecks(Lp, LoopScalarPreHeader);
8310
8311 // Generate the code that checks at runtime if arrays overlap. We put the
8312 // checks into a separate block to make the more common case of few elements
8313 // faster.
8314 EPI.MemSafetyCheck = emitMemRuntimeChecks(Lp, LoopScalarPreHeader);
8315
8316 // Generate the iteration count check for the main loop, *after* the check
8317 // for the epilogue loop, so that the path-length is shorter for the case
8318 // that goes directly through the vector epilogue. The longer-path length for
8319 // the main loop is compensated for, by the gain from vectorizing the larger
8320 // trip count. Note: the branch will get updated later on when we vectorize
8321 // the epilogue.
8322 EPI.MainLoopIterationCountCheck =
8323 emitMinimumIterationCountCheck(Lp, LoopScalarPreHeader, false);
8324
8325 // Generate the induction variable.
8326 OldInduction = Legal->getPrimaryInduction();
8327 Type *IdxTy = Legal->getWidestInductionType();
8328 Value *StartIdx = ConstantInt::get(IdxTy, 0);
8329 Constant *Step = ConstantInt::get(IdxTy, VF.getKnownMinValue() * UF);
8330 Value *CountRoundDown = getOrCreateVectorTripCount(Lp);
8331 EPI.VectorTripCount = CountRoundDown;
8332 Induction =
8333 createInductionVariable(Lp, StartIdx, CountRoundDown, Step,
8334 getDebugLocFromInstOrOperands(OldInduction));
8335
8336 // Skip induction resume value creation here because they will be created in
8337 // the second pass. If we created them here, they wouldn't be used anyway,
8338 // because the vplan in the second pass still contains the inductions from the
8339 // original loop.
8340
8341 return completeLoopSkeleton(Lp, OrigLoopID);
8342}
8343
8344void EpilogueVectorizerMainLoop::printDebugTracesAtStart() {
8345 LLVM_DEBUG({do { } while (false)
8346 dbgs() << "Create Skeleton for epilogue vectorized loop (first pass)\n"do { } while (false)
8347 << "Main Loop VF:" << EPI.MainLoopVF.getKnownMinValue()do { } while (false)
8348 << ", Main Loop UF:" << EPI.MainLoopUFdo { } while (false)
8349 << ", Epilogue Loop VF:" << EPI.EpilogueVF.getKnownMinValue()do { } while (false)
8350 << ", Epilogue Loop UF:" << EPI.EpilogueUF << "\n";do { } while (false)
8351 })do { } while (false);
8352}
8353
8354void EpilogueVectorizerMainLoop::printDebugTracesAtEnd() {
8355 DEBUG_WITH_TYPE(VerboseDebug, {do { } while (false)
8356 dbgs() << "intermediate fn:\n" << *Induction->getFunction() << "\n";do { } while (false)
8357 })do { } while (false);
8358}
8359
8360BasicBlock *EpilogueVectorizerMainLoop::emitMinimumIterationCountCheck(
8361 Loop *L, BasicBlock *Bypass, bool ForEpilogue) {
8362 assert(L && "Expected valid Loop.")((void)0);
8363 assert(Bypass && "Expected valid bypass basic block.")((void)0);
8364 unsigned VFactor =
8365 ForEpilogue ? EPI.EpilogueVF.getKnownMinValue() : VF.getKnownMinValue();
8366 unsigned UFactor = ForEpilogue ? EPI.EpilogueUF : UF;
8367 Value *Count = getOrCreateTripCount(L);
8368 // Reuse existing vector loop preheader for TC checks.
8369 // Note that new preheader block is generated for vector loop.
8370 BasicBlock *const TCCheckBlock = LoopVectorPreHeader;
8371 IRBuilder<> Builder(TCCheckBlock->getTerminator());
8372
8373 // Generate code to check if the loop's trip count is less than VF * UF of the
8374 // main vector loop.
8375 auto P = Cost->requiresScalarEpilogue(ForEpilogue ? EPI.EpilogueVF : VF) ?
8376 ICmpInst::ICMP_ULE : ICmpInst::ICMP_ULT;
8377
8378 Value *CheckMinIters = Builder.CreateICmp(
8379 P, Count, ConstantInt::get(Count->getType(), VFactor * UFactor),
8380 "min.iters.check");
8381
8382 if (!ForEpilogue)
8383 TCCheckBlock->setName("vector.main.loop.iter.check");
8384
8385 // Create new preheader for vector loop.
8386 LoopVectorPreHeader = SplitBlock(TCCheckBlock, TCCheckBlock->getTerminator(),
8387 DT, LI, nullptr, "vector.ph");
8388
8389 if (ForEpilogue) {
8390 assert(DT->properlyDominates(DT->getNode(TCCheckBlock),((void)0)
8391 DT->getNode(Bypass)->getIDom()) &&((void)0)
8392 "TC check is expected to dominate Bypass")((void)0);
8393
8394 // Update dominator for Bypass & LoopExit.
8395 DT->changeImmediateDominator(Bypass, TCCheckBlock);
8396 if (!Cost->requiresScalarEpilogue(EPI.EpilogueVF))
8397 // For loops with multiple exits, there's no edge from the middle block
8398 // to exit blocks (as the epilogue must run) and thus no need to update
8399 // the immediate dominator of the exit blocks.
8400 DT->changeImmediateDominator(LoopExitBlock, TCCheckBlock);
8401
8402 LoopBypassBlocks.push_back(TCCheckBlock);
8403
8404 // Save the trip count so we don't have to regenerate it in the
8405 // vec.epilog.iter.check. This is safe to do because the trip count
8406 // generated here dominates the vector epilog iter check.
8407 EPI.TripCount = Count;
8408 }
8409
8410 ReplaceInstWithInst(
8411 TCCheckBlock->getTerminator(),
8412 BranchInst::Create(Bypass, LoopVectorPreHeader, CheckMinIters));
8413
8414 return TCCheckBlock;
8415}
8416
8417//===--------------------------------------------------------------------===//
8418// EpilogueVectorizerEpilogueLoop
8419//===--------------------------------------------------------------------===//
8420
8421/// This function is partially responsible for generating the control flow
8422/// depicted in https://llvm.org/docs/Vectorizers.html#epilogue-vectorization.
8423BasicBlock *
8424EpilogueVectorizerEpilogueLoop::createEpilogueVectorizedLoopSkeleton() {
8425 MDNode *OrigLoopID = OrigLoop->getLoopID();
8426 Loop *Lp = createVectorLoopSkeleton("vec.epilog.");
8427
8428 // Now, compare the remaining count and if there aren't enough iterations to
8429 // execute the vectorized epilogue skip to the scalar part.
8430 BasicBlock *VecEpilogueIterationCountCheck = LoopVectorPreHeader;
8431 VecEpilogueIterationCountCheck->setName("vec.epilog.iter.check");
8432 LoopVectorPreHeader =
8433 SplitBlock(LoopVectorPreHeader, LoopVectorPreHeader->getTerminator(), DT,
8434 LI, nullptr, "vec.epilog.ph");
8435 emitMinimumVectorEpilogueIterCountCheck(Lp, LoopScalarPreHeader,
8436 VecEpilogueIterationCountCheck);
8437
8438 // Adjust the control flow taking the state info from the main loop
8439 // vectorization into account.
8440 assert(EPI.MainLoopIterationCountCheck && EPI.EpilogueIterationCountCheck &&((void)0)
8441 "expected this to be saved from the previous pass.")((void)0);
8442 EPI.MainLoopIterationCountCheck->getTerminator()->replaceUsesOfWith(
8443 VecEpilogueIterationCountCheck, LoopVectorPreHeader);
8444
8445 DT->changeImmediateDominator(LoopVectorPreHeader,
8446 EPI.MainLoopIterationCountCheck);
8447
8448 EPI.EpilogueIterationCountCheck->getTerminator()->replaceUsesOfWith(
8449 VecEpilogueIterationCountCheck, LoopScalarPreHeader);
8450
8451 if (EPI.SCEVSafetyCheck)
8452 EPI.SCEVSafetyCheck->getTerminator()->replaceUsesOfWith(
8453 VecEpilogueIterationCountCheck, LoopScalarPreHeader);
8454 if (EPI.MemSafetyCheck)
8455 EPI.MemSafetyCheck->getTerminator()->replaceUsesOfWith(
8456 VecEpilogueIterationCountCheck, LoopScalarPreHeader);
8457
8458 DT->changeImmediateDominator(
8459 VecEpilogueIterationCountCheck,
8460 VecEpilogueIterationCountCheck->getSinglePredecessor());
8461
8462 DT->changeImmediateDominator(LoopScalarPreHeader,
8463 EPI.EpilogueIterationCountCheck);
8464 if (!Cost->requiresScalarEpilogue(EPI.EpilogueVF))
8465 // If there is an epilogue which must run, there's no edge from the
8466 // middle block to exit blocks and thus no need to update the immediate
8467 // dominator of the exit blocks.
8468 DT->changeImmediateDominator(LoopExitBlock,
8469 EPI.EpilogueIterationCountCheck);
8470
8471 // Keep track of bypass blocks, as they feed start values to the induction
8472 // phis in the scalar loop preheader.
8473 if (EPI.SCEVSafetyCheck)
8474 LoopBypassBlocks.push_back(EPI.SCEVSafetyCheck);
8475 if (EPI.MemSafetyCheck)
8476 LoopBypassBlocks.push_back(EPI.MemSafetyCheck);
8477 LoopBypassBlocks.push_back(EPI.EpilogueIterationCountCheck);
8478
8479 // Generate a resume induction for the vector epilogue and put it in the
8480 // vector epilogue preheader
8481 Type *IdxTy = Legal->getWidestInductionType();
8482 PHINode *EPResumeVal = PHINode::Create(IdxTy, 2, "vec.epilog.resume.val",
8483 LoopVectorPreHeader->getFirstNonPHI());
8484 EPResumeVal->addIncoming(EPI.VectorTripCount, VecEpilogueIterationCountCheck);
8485 EPResumeVal->addIncoming(ConstantInt::get(IdxTy, 0),
8486 EPI.MainLoopIterationCountCheck);
8487
8488 // Generate the induction variable.
8489 OldInduction = Legal->getPrimaryInduction();
8490 Value *CountRoundDown = getOrCreateVectorTripCount(Lp);
8491 Constant *Step = ConstantInt::get(IdxTy, VF.getKnownMinValue() * UF);
8492 Value *StartIdx = EPResumeVal;
8493 Induction =
8494 createInductionVariable(Lp, StartIdx, CountRoundDown, Step,
8495 getDebugLocFromInstOrOperands(OldInduction));
8496
8497 // Generate induction resume values. These variables save the new starting
8498 // indexes for the scalar loop. They are used to test if there are any tail
8499 // iterations left once the vector loop has completed.
8500 // Note that when the vectorized epilogue is skipped due to iteration count
8501 // check, then the resume value for the induction variable comes from
8502 // the trip count of the main vector loop, hence passing the AdditionalBypass
8503 // argument.
8504 createInductionResumeValues(Lp, CountRoundDown,
8505 {VecEpilogueIterationCountCheck,
8506 EPI.VectorTripCount} /* AdditionalBypass */);
8507
8508 AddRuntimeUnrollDisableMetaData(Lp);
8509 return completeLoopSkeleton(Lp, OrigLoopID);
8510}
8511
8512BasicBlock *
8513EpilogueVectorizerEpilogueLoop::emitMinimumVectorEpilogueIterCountCheck(
8514 Loop *L, BasicBlock *Bypass, BasicBlock *Insert) {
8515
8516 assert(EPI.TripCount &&((void)0)
8517 "Expected trip count to have been safed in the first pass.")((void)0);
8518 assert(((void)0)
8519 (!isa<Instruction>(EPI.TripCount) ||((void)0)
8520 DT->dominates(cast<Instruction>(EPI.TripCount)->getParent(), Insert)) &&((void)0)
8521 "saved trip count does not dominate insertion point.")((void)0);
8522 Value *TC = EPI.TripCount;
8523 IRBuilder<> Builder(Insert->getTerminator());
8524 Value *Count = Builder.CreateSub(TC, EPI.VectorTripCount, "n.vec.remaining");
8525
8526 // Generate code to check if the loop's trip count is less than VF * UF of the
8527 // vector epilogue loop.
8528 auto P = Cost->requiresScalarEpilogue(EPI.EpilogueVF) ?
8529 ICmpInst::ICMP_ULE : ICmpInst::ICMP_ULT;
8530
8531 Value *CheckMinIters = Builder.CreateICmp(
8532 P, Count,
8533 ConstantInt::get(Count->getType(),
8534 EPI.EpilogueVF.getKnownMinValue() * EPI.EpilogueUF),
8535 "min.epilog.iters.check");
8536
8537 ReplaceInstWithInst(
8538 Insert->getTerminator(),
8539 BranchInst::Create(Bypass, LoopVectorPreHeader, CheckMinIters));
8540
8541 LoopBypassBlocks.push_back(Insert);
8542 return Insert;
8543}
8544
8545void EpilogueVectorizerEpilogueLoop::printDebugTracesAtStart() {
8546 LLVM_DEBUG({do { } while (false)
8547 dbgs() << "Create Skeleton for epilogue vectorized loop (second pass)\n"do { } while (false)
8548 << "Epilogue Loop VF:" << EPI.EpilogueVF.getKnownMinValue()do { } while (false)
8549 << ", Epilogue Loop UF:" << EPI.EpilogueUF << "\n";do { } while (false)
8550 })do { } while (false);
8551}
8552
8553void EpilogueVectorizerEpilogueLoop::printDebugTracesAtEnd() {
8554 DEBUG_WITH_TYPE(VerboseDebug, {do { } while (false)
8555 dbgs() << "final fn:\n" << *Induction->getFunction() << "\n";do { } while (false)
8556 })do { } while (false);
8557}
8558
8559bool LoopVectorizationPlanner::getDecisionAndClampRange(
8560 const std::function<bool(ElementCount)> &Predicate, VFRange &Range) {
8561 assert(!Range.isEmpty() && "Trying to test an empty VF range.")((void)0);
8562 bool PredicateAtRangeStart = Predicate(Range.Start);
8563
8564 for (ElementCount TmpVF = Range.Start * 2;
8565 ElementCount::isKnownLT(TmpVF, Range.End); TmpVF *= 2)
8566 if (Predicate(TmpVF) != PredicateAtRangeStart) {
8567 Range.End = TmpVF;
8568 break;
8569 }
8570
8571 return PredicateAtRangeStart;
8572}
8573
8574/// Build VPlans for the full range of feasible VF's = {\p MinVF, 2 * \p MinVF,
8575/// 4 * \p MinVF, ..., \p MaxVF} by repeatedly building a VPlan for a sub-range
8576/// of VF's starting at a given VF and extending it as much as possible. Each
8577/// vectorization decision can potentially shorten this sub-range during
8578/// buildVPlan().
8579void LoopVectorizationPlanner::buildVPlans(ElementCount MinVF,
8580 ElementCount MaxVF) {
8581 auto MaxVFPlusOne = MaxVF.getWithIncrement(1);
8582 for (ElementCount VF = MinVF; ElementCount::isKnownLT(VF, MaxVFPlusOne);) {
8583 VFRange SubRange = {VF, MaxVFPlusOne};
8584 VPlans.push_back(buildVPlan(SubRange));
8585 VF = SubRange.End;
8586 }
8587}
8588
8589VPValue *VPRecipeBuilder::createEdgeMask(BasicBlock *Src, BasicBlock *Dst,
8590 VPlanPtr &Plan) {
8591 assert(is_contained(predecessors(Dst), Src) && "Invalid edge")((void)0);
8592
8593 // Look for cached value.
8594 std::pair<BasicBlock *, BasicBlock *> Edge(Src, Dst);
8595 EdgeMaskCacheTy::iterator ECEntryIt = EdgeMaskCache.find(Edge);
8596 if (ECEntryIt != EdgeMaskCache.end())
8597 return ECEntryIt->second;
8598
8599 VPValue *SrcMask = createBlockInMask(Src, Plan);
8600
8601 // The terminator has to be a branch inst!
8602 BranchInst *BI = dyn_cast<BranchInst>(Src->getTerminator());
8603 assert(BI && "Unexpected terminator found")((void)0);
8604
8605 if (!BI->isConditional() || BI->getSuccessor(0) == BI->getSuccessor(1))
8606 return EdgeMaskCache[Edge] = SrcMask;
8607
8608 // If source is an exiting block, we know the exit edge is dynamically dead
8609 // in the vector loop, and thus we don't need to restrict the mask. Avoid
8610 // adding uses of an otherwise potentially dead instruction.
8611 if (OrigLoop->isLoopExiting(Src))
8612 return EdgeMaskCache[Edge] = SrcMask;
8613
8614 VPValue *EdgeMask = Plan->getOrAddVPValue(BI->getCondition());
8615 assert(EdgeMask && "No Edge Mask found for condition")((void)0);
8616
8617 if (BI->getSuccessor(0) != Dst)
8618 EdgeMask = Builder.createNot(EdgeMask);
8619
8620 if (SrcMask) { // Otherwise block in-mask is all-one, no need to AND.
8621 // The condition is 'SrcMask && EdgeMask', which is equivalent to
8622 // 'select i1 SrcMask, i1 EdgeMask, i1 false'.
8623 // The select version does not introduce new UB if SrcMask is false and
8624 // EdgeMask is poison. Using 'and' here introduces undefined behavior.
8625 VPValue *False = Plan->getOrAddVPValue(
8626 ConstantInt::getFalse(BI->getCondition()->getType()));
8627 EdgeMask = Builder.createSelect(SrcMask, EdgeMask, False);
8628 }
8629
8630 return EdgeMaskCache[Edge] = EdgeMask;
8631}
8632
8633VPValue *VPRecipeBuilder::createBlockInMask(BasicBlock *BB, VPlanPtr &Plan) {
8634 assert(OrigLoop->contains(BB) && "Block is not a part of a loop")((void)0);
8635
8636 // Look for cached value.
8637 BlockMaskCacheTy::iterator BCEntryIt = BlockMaskCache.find(BB);
8638 if (BCEntryIt != BlockMaskCache.end())
8639 return BCEntryIt->second;
8640
8641 // All-one mask is modelled as no-mask following the convention for masked
8642 // load/store/gather/scatter. Initialize BlockMask to no-mask.
8643 VPValue *BlockMask = nullptr;
8644
8645 if (OrigLoop->getHeader() == BB) {
8646 if (!CM.blockNeedsPredication(BB))
8647 return BlockMaskCache[BB] = BlockMask; // Loop incoming mask is all-one.
8648
8649 // Create the block in mask as the first non-phi instruction in the block.
8650 VPBuilder::InsertPointGuard Guard(Builder);
8651 auto NewInsertionPoint = Builder.getInsertBlock()->getFirstNonPhi();
8652 Builder.setInsertPoint(Builder.getInsertBlock(), NewInsertionPoint);
8653
8654 // Introduce the early-exit compare IV <= BTC to form header block mask.
8655 // This is used instead of IV < TC because TC may wrap, unlike BTC.
8656 // Start by constructing the desired canonical IV.
8657 VPValue *IV = nullptr;
8658 if (Legal->getPrimaryInduction())
8659 IV = Plan->getOrAddVPValue(Legal->getPrimaryInduction());
8660 else {
8661 auto IVRecipe = new VPWidenCanonicalIVRecipe();
8662 Builder.getInsertBlock()->insert(IVRecipe, NewInsertionPoint);
8663 IV = IVRecipe->getVPSingleValue();
8664 }
8665 VPValue *BTC = Plan->getOrCreateBackedgeTakenCount();
8666 bool TailFolded = !CM.isScalarEpilogueAllowed();
8667
8668 if (TailFolded && CM.TTI.emitGetActiveLaneMask()) {
8669 // While ActiveLaneMask is a binary op that consumes the loop tripcount
8670 // as a second argument, we only pass the IV here and extract the
8671 // tripcount from the transform state where codegen of the VP instructions
8672 // happen.
8673 BlockMask = Builder.createNaryOp(VPInstruction::ActiveLaneMask, {IV});
8674 } else {
8675 BlockMask = Builder.createNaryOp(VPInstruction::ICmpULE, {IV, BTC});
8676 }
8677 return BlockMaskCache[BB] = BlockMask;
8678 }
8679
8680 // This is the block mask. We OR all incoming edges.
8681 for (auto *Predecessor : predecessors(BB)) {
8682 VPValue *EdgeMask = createEdgeMask(Predecessor, BB, Plan);
8683 if (!EdgeMask) // Mask of predecessor is all-one so mask of block is too.
8684 return BlockMaskCache[BB] = EdgeMask;
8685
8686 if (!BlockMask) { // BlockMask has its initialized nullptr value.
8687 BlockMask = EdgeMask;
8688 continue;
8689 }
8690
8691 BlockMask = Builder.createOr(BlockMask, EdgeMask);
8692 }
8693
8694 return BlockMaskCache[BB] = BlockMask;
8695}
8696
8697VPRecipeBase *VPRecipeBuilder::tryToWidenMemory(Instruction *I,
8698 ArrayRef<VPValue *> Operands,
8699 VFRange &Range,
8700 VPlanPtr &Plan) {
8701 assert((isa<LoadInst>(I) || isa<StoreInst>(I)) &&((void)0)
8702 "Must be called with either a load or store")((void)0);
8703
8704 auto willWiden = [&](ElementCount VF) -> bool {
8705 if (VF.isScalar())
8706 return false;
8707 LoopVectorizationCostModel::InstWidening Decision =
8708 CM.getWideningDecision(I, VF);
8709 assert(Decision != LoopVectorizationCostModel::CM_Unknown &&((void)0)
8710 "CM decision should be taken at this point.")((void)0);
8711 if (Decision == LoopVectorizationCostModel::CM_Interleave)
8712 return true;
8713 if (CM.isScalarAfterVectorization(I, VF) ||
8714 CM.isProfitableToScalarize(I, VF))
8715 return false;
8716 return Decision != LoopVectorizationCostModel::CM_Scalarize;
8717 };
8718
8719 if (!LoopVectorizationPlanner::getDecisionAndClampRange(willWiden, Range))
8720 return nullptr;
8721
8722 VPValue *Mask = nullptr;
8723 if (Legal->isMaskRequired(I))
8724 Mask = createBlockInMask(I->getParent(), Plan);
8725
8726 if (LoadInst *Load = dyn_cast<LoadInst>(I))
8727 return new VPWidenMemoryInstructionRecipe(*Load, Operands[0], Mask);
8728
8729 StoreInst *Store = cast<StoreInst>(I);
8730 return new VPWidenMemoryInstructionRecipe(*Store, Operands[1], Operands[0],
8731 Mask);
8732}
8733
8734VPWidenIntOrFpInductionRecipe *
8735VPRecipeBuilder::tryToOptimizeInductionPHI(PHINode *Phi,
8736 ArrayRef<VPValue *> Operands) const {
8737 // Check if this is an integer or fp induction. If so, build the recipe that
8738 // produces its scalar and vector values.
8739 InductionDescriptor II = Legal->getInductionVars().lookup(Phi);
8740 if (II.getKind() == InductionDescriptor::IK_IntInduction ||
8741 II.getKind() == InductionDescriptor::IK_FpInduction) {
8742 assert(II.getStartValue() ==((void)0)
8743 Phi->getIncomingValueForBlock(OrigLoop->getLoopPreheader()))((void)0);
8744 const SmallVectorImpl<Instruction *> &Casts = II.getCastInsts();
8745 return new VPWidenIntOrFpInductionRecipe(
8746 Phi, Operands[0], Casts.empty() ? nullptr : Casts.front());
8747 }
8748
8749 return nullptr;
8750}
8751
8752VPWidenIntOrFpInductionRecipe *VPRecipeBuilder::tryToOptimizeInductionTruncate(
8753 TruncInst *I, ArrayRef<VPValue *> Operands, VFRange &Range,
8754 VPlan &Plan) const {
8755 // Optimize the special case where the source is a constant integer
8756 // induction variable. Notice that we can only optimize the 'trunc' case
8757 // because (a) FP conversions lose precision, (b) sext/zext may wrap, and
8758 // (c) other casts depend on pointer size.
8759
8760 // Determine whether \p K is a truncation based on an induction variable that
8761 // can be optimized.
8762 auto isOptimizableIVTruncate =
8763 [&](Instruction *K) -> std::function<bool(ElementCount)> {
8764 return [=](ElementCount VF) -> bool {
8765 return CM.isOptimizableIVTruncate(K, VF);
8766 };
8767 };
8768
8769 if (LoopVectorizationPlanner::getDecisionAndClampRange(
8770 isOptimizableIVTruncate(I), Range)) {
8771
8772 InductionDescriptor II =
8773 Legal->getInductionVars().lookup(cast<PHINode>(I->getOperand(0)));
8774 VPValue *Start = Plan.getOrAddVPValue(II.getStartValue());
8775 return new VPWidenIntOrFpInductionRecipe(cast<PHINode>(I->getOperand(0)),
8776 Start, nullptr, I);
8777 }
8778 return nullptr;
8779}
8780
8781VPRecipeOrVPValueTy VPRecipeBuilder::tryToBlend(PHINode *Phi,
8782 ArrayRef<VPValue *> Operands,
8783 VPlanPtr &Plan) {
8784 // If all incoming values are equal, the incoming VPValue can be used directly
8785 // instead of creating a new VPBlendRecipe.
8786 VPValue *FirstIncoming = Operands[0];
8787 if (all_of(Operands, [FirstIncoming](const VPValue *Inc) {
8788 return FirstIncoming == Inc;
8789 })) {
8790 return Operands[0];
8791 }
8792
8793 // We know that all PHIs in non-header blocks are converted into selects, so
8794 // we don't have to worry about the insertion order and we can just use the
8795 // builder. At this point we generate the predication tree. There may be
8796 // duplications since this is a simple recursive scan, but future
8797 // optimizations will clean it up.
8798 SmallVector<VPValue *, 2> OperandsWithMask;
8799 unsigned NumIncoming = Phi->getNumIncomingValues();
8800
8801 for (unsigned In = 0; In < NumIncoming; In++) {
8802 VPValue *EdgeMask =
8803 createEdgeMask(Phi->getIncomingBlock(In), Phi->getParent(), Plan);
8804 assert((EdgeMask || NumIncoming == 1) &&((void)0)
8805 "Multiple predecessors with one having a full mask")((void)0);
8806 OperandsWithMask.push_back(Operands[In]);
8807 if (EdgeMask)
8808 OperandsWithMask.push_back(EdgeMask);
8809 }
8810 return toVPRecipeResult(new VPBlendRecipe(Phi, OperandsWithMask));
8811}
8812
8813VPWidenCallRecipe *VPRecipeBuilder::tryToWidenCall(CallInst *CI,
8814 ArrayRef<VPValue *> Operands,
8815 VFRange &Range) const {
8816
8817 bool IsPredicated = LoopVectorizationPlanner::getDecisionAndClampRange(
8818 [this, CI](ElementCount VF) { return CM.isScalarWithPredication(CI); },
8819 Range);
8820
8821 if (IsPredicated)
8822 return nullptr;
8823
8824 Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
8825 if (ID && (ID == Intrinsic::assume || ID == Intrinsic::lifetime_end ||
8826 ID == Intrinsic::lifetime_start || ID == Intrinsic::sideeffect ||
8827 ID == Intrinsic::pseudoprobe ||
8828 ID == Intrinsic::experimental_noalias_scope_decl))
8829 return nullptr;
8830
8831 auto willWiden = [&](ElementCount VF) -> bool {
8832 Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
8833 // The following case may be scalarized depending on the VF.
8834 // The flag shows whether we use Intrinsic or a usual Call for vectorized
8835 // version of the instruction.
8836 // Is it beneficial to perform intrinsic call compared to lib call?
8837 bool NeedToScalarize = false;
8838 InstructionCost CallCost = CM.getVectorCallCost(CI, VF, NeedToScalarize);
8839 InstructionCost IntrinsicCost = ID ? CM.getVectorIntrinsicCost(CI, VF) : 0;
8840 bool UseVectorIntrinsic = ID && IntrinsicCost <= CallCost;
8841 return UseVectorIntrinsic || !NeedToScalarize;
8842 };
8843
8844 if (!LoopVectorizationPlanner::getDecisionAndClampRange(willWiden, Range))
8845 return nullptr;
8846
8847 ArrayRef<VPValue *> Ops = Operands.take_front(CI->getNumArgOperands());
8848 return new VPWidenCallRecipe(*CI, make_range(Ops.begin(), Ops.end()));
8849}
8850
8851bool VPRecipeBuilder::shouldWiden(Instruction *I, VFRange &Range) const {
8852 assert(!isa<BranchInst>(I) && !isa<PHINode>(I) && !isa<LoadInst>(I) &&((void)0)
8853 !isa<StoreInst>(I) && "Instruction should have been handled earlier")((void)0);
8854 // Instruction should be widened, unless it is scalar after vectorization,
8855 // scalarization is profitable or it is predicated.
8856 auto WillScalarize = [this, I](ElementCount VF) -> bool {
8857 return CM.isScalarAfterVectorization(I, VF) ||
8858 CM.isProfitableToScalarize(I, VF) || CM.isScalarWithPredication(I);
8859 };
8860 return !LoopVectorizationPlanner::getDecisionAndClampRange(WillScalarize,
8861 Range);
8862}
8863
8864VPWidenRecipe *VPRecipeBuilder::tryToWiden(Instruction *I,
8865 ArrayRef<VPValue *> Operands) const {
8866 auto IsVectorizableOpcode = [](unsigned Opcode) {
8867 switch (Opcode) {
8868 case Instruction::Add:
8869 case Instruction::And:
8870 case Instruction::AShr:
8871 case Instruction::BitCast:
8872 case Instruction::FAdd:
8873 case Instruction::FCmp:
8874 case Instruction::FDiv:
8875 case Instruction::FMul:
8876 case Instruction::FNeg:
8877 case Instruction::FPExt:
8878 case Instruction::FPToSI:
8879 case Instruction::FPToUI:
8880 case Instruction::FPTrunc:
8881 case Instruction::FRem:
8882 case Instruction::FSub:
8883 case Instruction::ICmp:
8884 case Instruction::IntToPtr:
8885 case Instruction::LShr:
8886 case Instruction::Mul:
8887 case Instruction::Or:
8888 case Instruction::PtrToInt:
8889 case Instruction::SDiv:
8890 case Instruction::Select:
8891 case Instruction::SExt:
8892 case Instruction::Shl:
8893 case Instruction::SIToFP:
8894 case Instruction::SRem:
8895 case Instruction::Sub:
8896 case Instruction::Trunc:
8897 case Instruction::UDiv:
8898 case Instruction::UIToFP:
8899 case Instruction::URem:
8900 case Instruction::Xor:
8901 case Instruction::ZExt:
8902 return true;
8903 }
8904 return false;
8905 };
8906
8907 if (!IsVectorizableOpcode(I->getOpcode()))
8908 return nullptr;
8909
8910 // Success: widen this instruction.
8911 return new VPWidenRecipe(*I, make_range(Operands.begin(), Operands.end()));
8912}
8913
8914void VPRecipeBuilder::fixHeaderPhis() {
8915 BasicBlock *OrigLatch = OrigLoop->getLoopLatch();
8916 for (VPWidenPHIRecipe *R : PhisToFix) {
8917 auto *PN = cast<PHINode>(R->getUnderlyingValue());
8918 VPRecipeBase *IncR =
8919 getRecipe(cast<Instruction>(PN->getIncomingValueForBlock(OrigLatch)));
8920 R->addOperand(IncR->getVPSingleValue());
8921 }
8922}
8923
8924VPBasicBlock *VPRecipeBuilder::handleReplication(
8925 Instruction *I, VFRange &Range, VPBasicBlock *VPBB,
8926 VPlanPtr &Plan) {
8927 bool IsUniform = LoopVectorizationPlanner::getDecisionAndClampRange(
8928 [&](ElementCount VF) { return CM.isUniformAfterVectorization(I, VF); },
8929 Range);
8930
8931 bool IsPredicated = LoopVectorizationPlanner::getDecisionAndClampRange(
8932 [&](ElementCount VF) { return CM.isPredicatedInst(I); }, Range);
8933
8934 // Even if the instruction is not marked as uniform, there are certain
8935 // intrinsic calls that can be effectively treated as such, so we check for
8936 // them here. Conservatively, we only do this for scalable vectors, since
8937 // for fixed-width VFs we can always fall back on full scalarization.
8938 if (!IsUniform && Range.Start.isScalable() && isa<IntrinsicInst>(I)) {
8939 switch (cast<IntrinsicInst>(I)->getIntrinsicID()) {
8940 case Intrinsic::assume:
8941 case Intrinsic::lifetime_start:
8942 case Intrinsic::lifetime_end:
8943 // For scalable vectors if one of the operands is variant then we still
8944 // want to mark as uniform, which will generate one instruction for just
8945 // the first lane of the vector. We can't scalarize the call in the same
8946 // way as for fixed-width vectors because we don't know how many lanes
8947 // there are.
8948 //
8949 // The reasons for doing it this way for scalable vectors are:
8950 // 1. For the assume intrinsic generating the instruction for the first
8951 // lane is still be better than not generating any at all. For
8952 // example, the input may be a splat across all lanes.
8953 // 2. For the lifetime start/end intrinsics the pointer operand only
8954 // does anything useful when the input comes from a stack object,
8955 // which suggests it should always be uniform. For non-stack objects
8956 // the effect is to poison the object, which still allows us to
8957 // remove the call.
8958 IsUniform = true;
8959 break;
8960 default:
8961 break;
8962 }
8963 }
8964
8965 auto *Recipe = new VPReplicateRecipe(I, Plan->mapToVPValues(I->operands()),
8966 IsUniform, IsPredicated);
8967 setRecipe(I, Recipe);
8968 Plan->addVPValue(I, Recipe);
8969
8970 // Find if I uses a predicated instruction. If so, it will use its scalar
8971 // value. Avoid hoisting the insert-element which packs the scalar value into
8972 // a vector value, as that happens iff all users use the vector value.
8973 for (VPValue *Op : Recipe->operands()) {
8974 auto *PredR = dyn_cast_or_null<VPPredInstPHIRecipe>(Op->getDef());
8975 if (!PredR)
8976 continue;
8977 auto *RepR =
8978 cast_or_null<VPReplicateRecipe>(PredR->getOperand(0)->getDef());
8979 assert(RepR->isPredicated() &&((void)0)
8980 "expected Replicate recipe to be predicated")((void)0);
8981 RepR->setAlsoPack(false);
8982 }
8983
8984 // Finalize the recipe for Instr, first if it is not predicated.
8985 if (!IsPredicated) {
8986 LLVM_DEBUG(dbgs() << "LV: Scalarizing:" << *I << "\n")do { } while (false);
8987 VPBB->appendRecipe(Recipe);
8988 return VPBB;
8989 }
8990 LLVM_DEBUG(dbgs() << "LV: Scalarizing and predicating:" << *I << "\n")do { } while (false);
8991 assert(VPBB->getSuccessors().empty() &&((void)0)
8992 "VPBB has successors when handling predicated replication.")((void)0);
8993 // Record predicated instructions for above packing optimizations.
8994 VPBlockBase *Region = createReplicateRegion(I, Recipe, Plan);
8995 VPBlockUtils::insertBlockAfter(Region, VPBB);
8996 auto *RegSucc = new VPBasicBlock();
8997 VPBlockUtils::insertBlockAfter(RegSucc, Region);
8998 return RegSucc;
8999}
9000
9001VPRegionBlock *VPRecipeBuilder::createReplicateRegion(Instruction *Instr,
9002 VPRecipeBase *PredRecipe,
9003 VPlanPtr &Plan) {
9004 // Instructions marked for predication are replicated and placed under an
9005 // if-then construct to prevent side-effects.
9006
9007 // Generate recipes to compute the block mask for this region.
9008 VPValue *BlockInMask = createBlockInMask(Instr->getParent(), Plan);
9009
9010 // Build the triangular if-then region.
9011 std::string RegionName = (Twine("pred.") + Instr->getOpcodeName()).str();
9012 assert(Instr->getParent() && "Predicated instruction not in any basic block")((void)0);
9013 auto *BOMRecipe = new VPBranchOnMaskRecipe(BlockInMask);
9014 auto *Entry = new VPBasicBlock(Twine(RegionName) + ".entry", BOMRecipe);
9015 auto *PHIRecipe = Instr->getType()->isVoidTy()
9016 ? nullptr
9017 : new VPPredInstPHIRecipe(Plan->getOrAddVPValue(Instr));
9018 if (PHIRecipe) {
9019 Plan->removeVPValueFor(Instr);
9020 Plan->addVPValue(Instr, PHIRecipe);
9021 }
9022 auto *Exit = new VPBasicBlock(Twine(RegionName) + ".continue", PHIRecipe);
9023 auto *Pred = new VPBasicBlock(Twine(RegionName) + ".if", PredRecipe);
9024 VPRegionBlock *Region = new VPRegionBlock(Entry, Exit, RegionName, true);
9025
9026 // Note: first set Entry as region entry and then connect successors starting
9027 // from it in order, to propagate the "parent" of each VPBasicBlock.
9028 VPBlockUtils::insertTwoBlocksAfter(Pred, Exit, BlockInMask, Entry);
9029 VPBlockUtils::connectBlocks(Pred, Exit);
9030
9031 return Region;
9032}
9033
9034VPRecipeOrVPValueTy
9035VPRecipeBuilder::tryToCreateWidenRecipe(Instruction *Instr,
9036 ArrayRef<VPValue *> Operands,
9037 VFRange &Range, VPlanPtr &Plan) {
9038 // First, check for specific widening recipes that deal with calls, memory
9039 // operations, inductions and Phi nodes.
9040 if (auto *CI = dyn_cast<CallInst>(Instr))
9041 return toVPRecipeResult(tryToWidenCall(CI, Operands, Range));
9042
9043 if (isa<LoadInst>(Instr) || isa<StoreInst>(Instr))
9044 return toVPRecipeResult(tryToWidenMemory(Instr, Operands, Range, Plan));
9045
9046 VPRecipeBase *Recipe;
9047 if (auto Phi = dyn_cast<PHINode>(Instr)) {
9048 if (Phi->getParent() != OrigLoop->getHeader())
9049 return tryToBlend(Phi, Operands, Plan);
9050 if ((Recipe = tryToOptimizeInductionPHI(Phi, Operands)))
9051 return toVPRecipeResult(Recipe);
9052
9053 VPWidenPHIRecipe *PhiRecipe = nullptr;
9054 if (Legal->isReductionVariable(Phi) || Legal->isFirstOrderRecurrence(Phi)) {
9055 VPValue *StartV = Operands[0];
9056 if (Legal->isReductionVariable(Phi)) {
9057 RecurrenceDescriptor &RdxDesc = Legal->getReductionVars()[Phi];
9058 assert(RdxDesc.getRecurrenceStartValue() ==((void)0)
9059 Phi->getIncomingValueForBlock(OrigLoop->getLoopPreheader()))((void)0);
9060 PhiRecipe = new VPReductionPHIRecipe(Phi, RdxDesc, *StartV,
9061 CM.isInLoopReduction(Phi),
9062 CM.useOrderedReductions(RdxDesc));
9063 } else {
9064 PhiRecipe = new VPFirstOrderRecurrencePHIRecipe(Phi, *StartV);
9065 }
9066
9067 // Record the incoming value from the backedge, so we can add the incoming
9068 // value from the backedge after all recipes have been created.
9069 recordRecipeOf(cast<Instruction>(
9070 Phi->getIncomingValueForBlock(OrigLoop->getLoopLatch())));
9071 PhisToFix.push_back(PhiRecipe);
9072 } else {
9073 // TODO: record start and backedge value for remaining pointer induction
9074 // phis.
9075 assert(Phi->getType()->isPointerTy() &&((void)0)
9076 "only pointer phis should be handled here")((void)0);
9077 PhiRecipe = new VPWidenPHIRecipe(Phi);
9078 }
9079
9080 return toVPRecipeResult(PhiRecipe);
9081 }
9082
9083 if (isa<TruncInst>(Instr) &&
9084 (Recipe = tryToOptimizeInductionTruncate(cast<TruncInst>(Instr), Operands,
9085 Range, *Plan)))
9086 return toVPRecipeResult(Recipe);
9087
9088 if (!shouldWiden(Instr, Range))
9089 return nullptr;
9090
9091 if (auto GEP = dyn_cast<GetElementPtrInst>(Instr))
9092 return toVPRecipeResult(new VPWidenGEPRecipe(
9093 GEP, make_range(Operands.begin(), Operands.end()), OrigLoop));
9094
9095 if (auto *SI = dyn_cast<SelectInst>(Instr)) {
9096 bool InvariantCond =
9097 PSE.getSE()->isLoopInvariant(PSE.getSCEV(SI->getOperand(0)), OrigLoop);
9098 return toVPRecipeResult(new VPWidenSelectRecipe(
9099 *SI, make_range(Operands.begin(), Operands.end()), InvariantCond));
9100 }
9101
9102 return toVPRecipeResult(tryToWiden(Instr, Operands));
9103}
9104
9105void LoopVectorizationPlanner::buildVPlansWithVPRecipes(ElementCount MinVF,
9106 ElementCount MaxVF) {
9107 assert(OrigLoop->isInnermost() && "Inner loop expected.")((void)0);
9108
9109 // Collect instructions from the original loop that will become trivially dead
9110 // in the vectorized loop. We don't need to vectorize these instructions. For
9111 // example, original induction update instructions can become dead because we
9112 // separately emit induction "steps" when generating code for the new loop.
9113 // Similarly, we create a new latch condition when setting up the structure
9114 // of the new loop, so the old one can become dead.
9115 SmallPtrSet<Instruction *, 4> DeadInstructions;
9116 collectTriviallyDeadInstructions(DeadInstructions);
9117
9118 // Add assume instructions we need to drop to DeadInstructions, to prevent
9119 // them from being added to the VPlan.
9120 // TODO: We only need to drop assumes in blocks that get flattend. If the
9121 // control flow is preserved, we should keep them.
9122 auto &ConditionalAssumes = Legal->getConditionalAssumes();
9123 DeadInstructions.insert(ConditionalAssumes.begin(), ConditionalAssumes.end());
9124
9125 MapVector<Instruction *, Instruction *> &SinkAfter = Legal->getSinkAfter();
9126 // Dead instructions do not need sinking. Remove them from SinkAfter.
9127 for (Instruction *I : DeadInstructions)
9128 SinkAfter.erase(I);
9129
9130 // Cannot sink instructions after dead instructions (there won't be any
9131 // recipes for them). Instead, find the first non-dead previous instruction.
9132 for (auto &P : Legal->getSinkAfter()) {
9133 Instruction *SinkTarget = P.second;
9134 Instruction *FirstInst = &*SinkTarget->getParent()->begin();
9135 (void)FirstInst;
9136 while (DeadInstructions.contains(SinkTarget)) {
9137 assert(((void)0)
9138 SinkTarget != FirstInst &&((void)0)
9139 "Must find a live instruction (at least the one feeding the "((void)0)
9140 "first-order recurrence PHI) before reaching beginning of the block")((void)0);
9141 SinkTarget = SinkTarget->getPrevNode();
9142 assert(SinkTarget != P.first &&((void)0)
9143 "sink source equals target, no sinking required")((void)0);
9144 }
9145 P.second = SinkTarget;
9146 }
9147
9148 auto MaxVFPlusOne = MaxVF.getWithIncrement(1);
9149 for (ElementCount VF = MinVF; ElementCount::isKnownLT(VF, MaxVFPlusOne);) {
9150 VFRange SubRange = {VF, MaxVFPlusOne};
9151 VPlans.push_back(
9152 buildVPlanWithVPRecipes(SubRange, DeadInstructions, SinkAfter));
9153 VF = SubRange.End;
9154 }
9155}
9156
9157VPlanPtr LoopVectorizationPlanner::buildVPlanWithVPRecipes(
9158 VFRange &Range, SmallPtrSetImpl<Instruction *> &DeadInstructions,
9159 const MapVector<Instruction *, Instruction *> &SinkAfter) {
9160
9161 SmallPtrSet<const InterleaveGroup<Instruction> *, 1> InterleaveGroups;
9162
9163 VPRecipeBuilder RecipeBuilder(OrigLoop, TLI, Legal, CM, PSE, Builder);
9164
9165 // ---------------------------------------------------------------------------
9166 // Pre-construction: record ingredients whose recipes we'll need to further
9167 // process after constructing the initial VPlan.
9168 // ---------------------------------------------------------------------------
9169
9170 // Mark instructions we'll need to sink later and their targets as
9171 // ingredients whose recipe we'll need to record.
9172 for (auto &Entry : SinkAfter) {
9173 RecipeBuilder.recordRecipeOf(Entry.first);
9174 RecipeBuilder.recordRecipeOf(Entry.second);
9175 }
9176 for (auto &Reduction : CM.getInLoopReductionChains()) {
9177 PHINode *Phi = Reduction.first;
9178 RecurKind Kind = Legal->getReductionVars()[Phi].getRecurrenceKind();
9179 const SmallVector<Instruction *, 4> &ReductionOperations = Reduction.second;
9180
9181 RecipeBuilder.recordRecipeOf(Phi);
9182 for (auto &R : ReductionOperations) {
9183 RecipeBuilder.recordRecipeOf(R);
9184 // For min/max reducitons, where we have a pair of icmp/select, we also
9185 // need to record the ICmp recipe, so it can be removed later.
9186 if (RecurrenceDescriptor::isMinMaxRecurrenceKind(Kind))
9187 RecipeBuilder.recordRecipeOf(cast<Instruction>(R->getOperand(0)));
9188 }
9189 }
9190
9191 // For each interleave group which is relevant for this (possibly trimmed)
9192 // Range, add it to the set of groups to be later applied to the VPlan and add
9193 // placeholders for its members' Recipes which we'll be replacing with a
9194 // single VPInterleaveRecipe.
9195 for (InterleaveGroup<Instruction> *IG : IAI.getInterleaveGroups()) {
9196 auto applyIG = [IG, this](ElementCount VF) -> bool {
9197 return (VF.isVector() && // Query is illegal for VF == 1
9198 CM.getWideningDecision(IG->getInsertPos(), VF) ==
9199 LoopVectorizationCostModel::CM_Interleave);
9200 };
9201 if (!getDecisionAndClampRange(applyIG, Range))
9202 continue;
9203 InterleaveGroups.insert(IG);
9204 for (unsigned i = 0; i < IG->getFactor(); i++)
9205 if (Instruction *Member = IG->getMember(i))
9206 RecipeBuilder.recordRecipeOf(Member);
9207 };
9208
9209 // ---------------------------------------------------------------------------
9210 // Build initial VPlan: Scan the body of the loop in a topological order to
9211 // visit each basic block after having visited its predecessor basic blocks.
9212 // ---------------------------------------------------------------------------
9213
9214 // Create a dummy pre-entry VPBasicBlock to start building the VPlan.
9215 auto Plan = std::make_unique<VPlan>();
9216 VPBasicBlock *VPBB = new VPBasicBlock("Pre-Entry");
9217 Plan->setEntry(VPBB);
9218
9219 // Scan the body of the loop in a topological order to visit each basic block
9220 // after having visited its predecessor basic blocks.
9221 LoopBlocksDFS DFS(OrigLoop);
9222 DFS.perform(LI);
9223
9224 for (BasicBlock *BB : make_range(DFS.beginRPO(), DFS.endRPO())) {
9225 // Relevant instructions from basic block BB will be grouped into VPRecipe
9226 // ingredients and fill a new VPBasicBlock.
9227 unsigned VPBBsForBB = 0;
9228 auto *FirstVPBBForBB = new VPBasicBlock(BB->getName());
9229 VPBlockUtils::insertBlockAfter(FirstVPBBForBB, VPBB);
9230 VPBB = FirstVPBBForBB;
9231 Builder.setInsertPoint(VPBB);
9232
9233 // Introduce each ingredient into VPlan.
9234 // TODO: Model and preserve debug instrinsics in VPlan.
9235 for (Instruction &I : BB->instructionsWithoutDebug()) {
9236 Instruction *Instr = &I;
9237
9238 // First filter out irrelevant instructions, to ensure no recipes are
9239 // built for them.
9240 if (isa<BranchInst>(Instr) || DeadInstructions.count(Instr))
9241 continue;
9242
9243 SmallVector<VPValue *, 4> Operands;
9244 auto *Phi = dyn_cast<PHINode>(Instr);
9245 if (Phi && Phi->getParent() == OrigLoop->getHeader()) {
9246 Operands.push_back(Plan->getOrAddVPValue(
9247 Phi->getIncomingValueForBlock(OrigLoop->getLoopPreheader())));
9248 } else {
9249 auto OpRange = Plan->mapToVPValues(Instr->operands());
9250 Operands = {OpRange.begin(), OpRange.end()};
9251 }
9252 if (auto RecipeOrValue = RecipeBuilder.tryToCreateWidenRecipe(
9253 Instr, Operands, Range, Plan)) {
9254 // If Instr can be simplified to an existing VPValue, use it.
9255 if (RecipeOrValue.is<VPValue *>()) {
9256 auto *VPV = RecipeOrValue.get<VPValue *>();
9257 Plan->addVPValue(Instr, VPV);
9258 // If the re-used value is a recipe, register the recipe for the
9259 // instruction, in case the recipe for Instr needs to be recorded.
9260 if (auto *R = dyn_cast_or_null<VPRecipeBase>(VPV->getDef()))
9261 RecipeBuilder.setRecipe(Instr, R);
9262 continue;
9263 }
9264 // Otherwise, add the new recipe.
9265 VPRecipeBase *Recipe = RecipeOrValue.get<VPRecipeBase *>();
9266 for (auto *Def : Recipe->definedValues()) {
9267 auto *UV = Def->getUnderlyingValue();
9268 Plan->addVPValue(UV, Def);
9269 }
9270
9271 RecipeBuilder.setRecipe(Instr, Recipe);
9272 VPBB->appendRecipe(Recipe);
9273 continue;
9274 }
9275
9276 // Otherwise, if all widening options failed, Instruction is to be
9277 // replicated. This may create a successor for VPBB.
9278 VPBasicBlock *NextVPBB =
9279 RecipeBuilder.handleReplication(Instr, Range, VPBB, Plan);
9280 if (NextVPBB != VPBB) {
9281 VPBB = NextVPBB;
9282 VPBB->setName(BB->hasName() ? BB->getName() + "." + Twine(VPBBsForBB++)
9283 : "");
9284 }
9285 }
9286 }
9287
9288 RecipeBuilder.fixHeaderPhis();
9289
9290 // Discard empty dummy pre-entry VPBasicBlock. Note that other VPBasicBlocks
9291 // may also be empty, such as the last one VPBB, reflecting original
9292 // basic-blocks with no recipes.
9293 VPBasicBlock *PreEntry = cast<VPBasicBlock>(Plan->getEntry());
9294 assert(PreEntry->empty() && "Expecting empty pre-entry block.")((void)0);
9295 VPBlockBase *Entry = Plan->setEntry(PreEntry->getSingleSuccessor());
9296 VPBlockUtils::disconnectBlocks(PreEntry, Entry);
9297 delete PreEntry;
9298
9299 // ---------------------------------------------------------------------------
9300 // Transform initial VPlan: Apply previously taken decisions, in order, to
9301 // bring the VPlan to its final state.
9302 // ---------------------------------------------------------------------------
9303
9304 // Apply Sink-After legal constraints.
9305 auto GetReplicateRegion = [](VPRecipeBase *R) -> VPRegionBlock * {
9306 auto *Region = dyn_cast_or_null<VPRegionBlock>(R->getParent()->getParent());
9307 if (Region && Region->isReplicator()) {
9308 assert(Region->getNumSuccessors() == 1 &&((void)0)
9309 Region->getNumPredecessors() == 1 && "Expected SESE region!")((void)0);
9310 assert(R->getParent()->size() == 1 &&((void)0)
9311 "A recipe in an original replicator region must be the only "((void)0)
9312 "recipe in its block")((void)0);
9313 return Region;
9314 }
9315 return nullptr;
9316 };
9317 for (auto &Entry : SinkAfter) {
9318 VPRecipeBase *Sink = RecipeBuilder.getRecipe(Entry.first);
9319 VPRecipeBase *Target = RecipeBuilder.getRecipe(Entry.second);
9320
9321 auto *TargetRegion = GetReplicateRegion(Target);
9322 auto *SinkRegion = GetReplicateRegion(Sink);
9323 if (!SinkRegion) {
9324 // If the sink source is not a replicate region, sink the recipe directly.
9325 if (TargetRegion) {
9326 // The target is in a replication region, make sure to move Sink to
9327 // the block after it, not into the replication region itself.
9328 VPBasicBlock *NextBlock =
9329 cast<VPBasicBlock>(TargetRegion->getSuccessors().front());
9330 Sink->moveBefore(*NextBlock, NextBlock->getFirstNonPhi());
9331 } else
9332 Sink->moveAfter(Target);
9333 continue;
9334 }
9335
9336 // The sink source is in a replicate region. Unhook the region from the CFG.
9337 auto *SinkPred = SinkRegion->getSinglePredecessor();
9338 auto *SinkSucc = SinkRegion->getSingleSuccessor();
9339 VPBlockUtils::disconnectBlocks(SinkPred, SinkRegion);
9340 VPBlockUtils::disconnectBlocks(SinkRegion, SinkSucc);
9341 VPBlockUtils::connectBlocks(SinkPred, SinkSucc);
9342
9343 if (TargetRegion) {
9344 // The target recipe is also in a replicate region, move the sink region
9345 // after the target region.
9346 auto *TargetSucc = TargetRegion->getSingleSuccessor();
9347 VPBlockUtils::disconnectBlocks(TargetRegion, TargetSucc);
9348 VPBlockUtils::connectBlocks(TargetRegion, SinkRegion);
9349 VPBlockUtils::connectBlocks(SinkRegion, TargetSucc);
9350 } else {
9351 // The sink source is in a replicate region, we need to move the whole
9352 // replicate region, which should only contain a single recipe in the
9353 // main block.
9354 auto *SplitBlock =
9355 Target->getParent()->splitAt(std::next(Target->getIterator()));
9356
9357 auto *SplitPred = SplitBlock->getSinglePredecessor();
9358
9359 VPBlockUtils::disconnectBlocks(SplitPred, SplitBlock);
9360 VPBlockUtils::connectBlocks(SplitPred, SinkRegion);
9361 VPBlockUtils::connectBlocks(SinkRegion, SplitBlock);
9362 if (VPBB == SplitPred)
9363 VPBB = SplitBlock;
9364 }
9365 }
9366
9367 // Introduce a recipe to combine the incoming and previous values of a
9368 // first-order recurrence.
9369 for (VPRecipeBase &R : Plan->getEntry()->getEntryBasicBlock()->phis()) {
9370 auto *RecurPhi = dyn_cast<VPFirstOrderRecurrencePHIRecipe>(&R);
9371 if (!RecurPhi)
9372 continue;
9373
9374 auto *RecurSplice = cast<VPInstruction>(
9375 Builder.createNaryOp(VPInstruction::FirstOrderRecurrenceSplice,
9376 {RecurPhi, RecurPhi->getBackedgeValue()}));
9377
9378 VPRecipeBase *PrevRecipe = RecurPhi->getBackedgeRecipe();
9379 if (auto *Region = GetReplicateRegion(PrevRecipe)) {
9380 VPBasicBlock *Succ = cast<VPBasicBlock>(Region->getSingleSuccessor());
9381 RecurSplice->moveBefore(*Succ, Succ->getFirstNonPhi());
9382 } else
9383 RecurSplice->moveAfter(PrevRecipe);
9384 RecurPhi->replaceAllUsesWith(RecurSplice);
9385 // Set the first operand of RecurSplice to RecurPhi again, after replacing
9386 // all users.
9387 RecurSplice->setOperand(0, RecurPhi);
9388 }
9389
9390 // Interleave memory: for each Interleave Group we marked earlier as relevant
9391 // for this VPlan, replace the Recipes widening its memory instructions with a
9392 // single VPInterleaveRecipe at its insertion point.
9393 for (auto IG : InterleaveGroups) {
9394 auto *Recipe = cast<VPWidenMemoryInstructionRecipe>(
9395 RecipeBuilder.getRecipe(IG->getInsertPos()));
9396 SmallVector<VPValue *, 4> StoredValues;
9397 for (unsigned i = 0; i < IG->getFactor(); ++i)
9398 if (auto *SI = dyn_cast_or_null<StoreInst>(IG->getMember(i))) {
9399 auto *StoreR =
9400 cast<VPWidenMemoryInstructionRecipe>(RecipeBuilder.getRecipe(SI));
9401 StoredValues.push_back(StoreR->getStoredValue());
9402 }
9403
9404 auto *VPIG = new VPInterleaveRecipe(IG, Recipe->getAddr(), StoredValues,
9405 Recipe->getMask());
9406 VPIG->insertBefore(Recipe);
9407 unsigned J = 0;
9408 for (unsigned i = 0; i < IG->getFactor(); ++i)
9409 if (Instruction *Member = IG->getMember(i)) {
9410 if (!Member->getType()->isVoidTy()) {
9411 VPValue *OriginalV = Plan->getVPValue(Member);
9412 Plan->removeVPValueFor(Member);
9413 Plan->addVPValue(Member, VPIG->getVPValue(J));
9414 OriginalV->replaceAllUsesWith(VPIG->getVPValue(J));
9415 J++;
9416 }
9417 RecipeBuilder.getRecipe(Member)->eraseFromParent();
9418 }
9419 }
9420
9421 // Adjust the recipes for any inloop reductions.
9422 adjustRecipesForInLoopReductions(Plan, RecipeBuilder, Range.Start);
9423
9424 // Finally, if tail is folded by masking, introduce selects between the phi
9425 // and the live-out instruction of each reduction, at the end of the latch.
9426 if (CM.foldTailByMasking() && !Legal->getReductionVars().empty()) {
9427 Builder.setInsertPoint(VPBB);
9428 auto *Cond = RecipeBuilder.createBlockInMask(OrigLoop->getHeader(), Plan);
9429 for (auto &Reduction : Legal->getReductionVars()) {
9430 if (CM.isInLoopReduction(Reduction.first))
9431 continue;
9432 VPValue *Phi = Plan->getOrAddVPValue(Reduction.first);
9433 VPValue *Red = Plan->getOrAddVPValue(Reduction.second.getLoopExitInstr());
9434 Builder.createNaryOp(Instruction::Select, {Cond, Red, Phi});
9435 }
9436 }
9437
9438 VPlanTransforms::sinkScalarOperands(*Plan);
9439 VPlanTransforms::mergeReplicateRegions(*Plan);
9440
9441 std::string PlanName;
9442 raw_string_ostream RSO(PlanName);
9443 ElementCount VF = Range.Start;
9444 Plan->addVF(VF);
9445 RSO << "Initial VPlan for VF={" << VF;
9446 for (VF *= 2; ElementCount::isKnownLT(VF, Range.End); VF *= 2) {
9447 Plan->addVF(VF);
9448 RSO << "," << VF;
9449 }
9450 RSO << "},UF>=1";
9451 RSO.flush();
9452 Plan->setName(PlanName);
9453
9454 return Plan;
9455}
9456
9457VPlanPtr LoopVectorizationPlanner::buildVPlan(VFRange &Range) {
9458 // Outer loop handling: They may require CFG and instruction level
9459 // transformations before even evaluating whether vectorization is profitable.
9460 // Since we cannot modify the incoming IR, we need to build VPlan upfront in
9461 // the vectorization pipeline.
9462 assert(!OrigLoop->isInnermost())((void)0);
9463 assert(EnableVPlanNativePath && "VPlan-native path is not enabled.")((void)0);
9464
9465 // Create new empty VPlan
9466 auto Plan = std::make_unique<VPlan>();
9467
9468 // Build hierarchical CFG
9469 VPlanHCFGBuilder HCFGBuilder(OrigLoop, LI, *Plan);
9470 HCFGBuilder.buildHierarchicalCFG();
9471
9472 for (ElementCount VF = Range.Start; ElementCount::isKnownLT(VF, Range.End);
9473 VF *= 2)
9474 Plan->addVF(VF);
9475
9476 if (EnableVPlanPredication) {
9477 VPlanPredicator VPP(*Plan);
9478 VPP.predicate();
9479
9480 // Avoid running transformation to recipes until masked code generation in
9481 // VPlan-native path is in place.
9482 return Plan;
9483 }
9484
9485 SmallPtrSet<Instruction *, 1> DeadInstructions;
9486 VPlanTransforms::VPInstructionsToVPRecipes(OrigLoop, Plan,
9487 Legal->getInductionVars(),
9488 DeadInstructions, *PSE.getSE());
9489 return Plan;
9490}
9491
9492// Adjust the recipes for any inloop reductions. The chain of instructions
9493// leading from the loop exit instr to the phi need to be converted to
9494// reductions, with one operand being vector and the other being the scalar
9495// reduction chain.
9496void LoopVectorizationPlanner::adjustRecipesForInLoopReductions(
9497 VPlanPtr &Plan, VPRecipeBuilder &RecipeBuilder, ElementCount MinVF) {
9498 for (auto &Reduction : CM.getInLoopReductionChains()) {
9499 PHINode *Phi = Reduction.first;
9500 RecurrenceDescriptor &RdxDesc = Legal->getReductionVars()[Phi];
9501 const SmallVector<Instruction *, 4> &ReductionOperations = Reduction.second;
9502
9503 if (MinVF.isScalar() && !CM.useOrderedReductions(RdxDesc))
9504 continue;
9505
9506 // ReductionOperations are orders top-down from the phi's use to the
9507 // LoopExitValue. We keep a track of the previous item (the Chain) to tell
9508 // which of the two operands will remain scalar and which will be reduced.
9509 // For minmax the chain will be the select instructions.
9510 Instruction *Chain = Phi;
9511 for (Instruction *R : ReductionOperations) {
9512 VPRecipeBase *WidenRecipe = RecipeBuilder.getRecipe(R);
9513 RecurKind Kind = RdxDesc.getRecurrenceKind();
9514
9515 VPValue *ChainOp = Plan->getVPValue(Chain);
9516 unsigned FirstOpId;
9517 if (RecurrenceDescriptor::isMinMaxRecurrenceKind(Kind)) {
9518 assert(isa<VPWidenSelectRecipe>(WidenRecipe) &&((void)0)
9519 "Expected to replace a VPWidenSelectSC")((void)0);
9520 FirstOpId = 1;
9521 } else {
9522 assert((MinVF.isScalar() || isa<VPWidenRecipe>(WidenRecipe)) &&((void)0)
9523 "Expected to replace a VPWidenSC")((void)0);
9524 FirstOpId = 0;
9525 }
9526 unsigned VecOpId =
9527 R->getOperand(FirstOpId) == Chain ? FirstOpId + 1 : FirstOpId;
9528 VPValue *VecOp = Plan->getVPValue(R->getOperand(VecOpId));
9529
9530 auto *CondOp = CM.foldTailByMasking()
9531 ? RecipeBuilder.createBlockInMask(R->getParent(), Plan)
9532 : nullptr;
9533 VPReductionRecipe *RedRecipe = new VPReductionRecipe(
9534 &RdxDesc, R, ChainOp, VecOp, CondOp, TTI);
9535 WidenRecipe->getVPSingleValue()->replaceAllUsesWith(RedRecipe);
9536 Plan->removeVPValueFor(R);
9537 Plan->addVPValue(R, RedRecipe);
9538 WidenRecipe->getParent()->insert(RedRecipe, WidenRecipe->getIterator());
9539 WidenRecipe->getVPSingleValue()->replaceAllUsesWith(RedRecipe);
9540 WidenRecipe->eraseFromParent();
9541
9542 if (RecurrenceDescriptor::isMinMaxRecurrenceKind(Kind)) {
9543 VPRecipeBase *CompareRecipe =
9544 RecipeBuilder.getRecipe(cast<Instruction>(R->getOperand(0)));
9545 assert(isa<VPWidenRecipe>(CompareRecipe) &&((void)0)
9546 "Expected to replace a VPWidenSC")((void)0);
9547 assert(cast<VPWidenRecipe>(CompareRecipe)->getNumUsers() == 0 &&((void)0)
9548 "Expected no remaining users")((void)0);
9549 CompareRecipe->eraseFromParent();
9550 }
9551 Chain = R;
9552 }
9553 }
9554}
9555
9556#if !defined(NDEBUG1) || defined(LLVM_ENABLE_DUMP)
9557void VPInterleaveRecipe::print(raw_ostream &O, const Twine &Indent,
9558 VPSlotTracker &SlotTracker) const {
9559 O << Indent << "INTERLEAVE-GROUP with factor " << IG->getFactor() << " at ";
9560 IG->getInsertPos()->printAsOperand(O, false);
9561 O << ", ";
9562 getAddr()->printAsOperand(O, SlotTracker);
9563 VPValue *Mask = getMask();
9564 if (Mask) {
9565 O << ", ";
9566 Mask->printAsOperand(O, SlotTracker);
9567 }
9568 for (unsigned i = 0; i < IG->getFactor(); ++i)
9569 if (Instruction *I = IG->getMember(i))
9570 O << "\n" << Indent << " " << VPlanIngredient(I) << " " << i;
9571}
9572#endif
9573
9574void VPWidenCallRecipe::execute(VPTransformState &State) {
9575 State.ILV->widenCallInstruction(*cast<CallInst>(getUnderlyingInstr()), this,
9576 *this, State);
9577}
9578
9579void VPWidenSelectRecipe::execute(VPTransformState &State) {
9580 State.ILV->widenSelectInstruction(*cast<SelectInst>(getUnderlyingInstr()),
9581 this, *this, InvariantCond, State);
9582}
9583
9584void VPWidenRecipe::execute(VPTransformState &State) {
9585 State.ILV->widenInstruction(*getUnderlyingInstr(), this, *this, State);
9586}
9587
9588void VPWidenGEPRecipe::execute(VPTransformState &State) {
9589 State.ILV->widenGEP(cast<GetElementPtrInst>(getUnderlyingInstr()), this,
9590 *this, State.UF, State.VF, IsPtrLoopInvariant,
9591 IsIndexLoopInvariant, State);
9592}
9593
9594void VPWidenIntOrFpInductionRecipe::execute(VPTransformState &State) {
9595 assert(!State.Instance && "Int or FP induction being replicated.")((void)0);
9596 State.ILV->widenIntOrFpInduction(IV, getStartValue()->getLiveInIRValue(),
9597 getTruncInst(), getVPValue(0),
9598 getCastValue(), State);
9599}
9600
9601void VPWidenPHIRecipe::execute(VPTransformState &State) {
9602 State.ILV->widenPHIInstruction(cast<PHINode>(getUnderlyingValue()), this,
9603 State);
9604}
9605
9606void VPBlendRecipe::execute(VPTransformState &State) {
9607 State.ILV->setDebugLocFromInst(Phi, &State.Builder);
9608 // We know that all PHIs in non-header blocks are converted into
9609 // selects, so we don't have to worry about the insertion order and we
9610 // can just use the builder.
9611 // At this point we generate the predication tree. There may be
9612 // duplications since this is a simple recursive scan, but future
9613 // optimizations will clean it up.
9614
9615 unsigned NumIncoming = getNumIncomingValues();
9616
9617 // Generate a sequence of selects of the form:
9618 // SELECT(Mask3, In3,
9619 // SELECT(Mask2, In2,
9620 // SELECT(Mask1, In1,
9621 // In0)))
9622 // Note that Mask0 is never used: lanes for which no path reaches this phi and
9623 // are essentially undef are taken from In0.
9624 InnerLoopVectorizer::VectorParts Entry(State.UF);
9625 for (unsigned In = 0; In < NumIncoming; ++In) {
9626 for (unsigned Part = 0; Part < State.UF; ++Part) {
9627 // We might have single edge PHIs (blocks) - use an identity
9628 // 'select' for the first PHI operand.
9629 Value *In0 = State.get(getIncomingValue(In), Part);
9630 if (In == 0)
9631 Entry[Part] = In0; // Initialize with the first incoming value.
9632 else {
9633 // Select between the current value and the previous incoming edge
9634 // based on the incoming mask.
9635 Value *Cond = State.get(getMask(In), Part);
9636 Entry[Part] =
9637 State.Builder.CreateSelect(Cond, In0, Entry[Part], "predphi");
9638 }
9639 }
9640 }
9641 for (unsigned Part = 0; Part < State.UF; ++Part)
9642 State.set(this, Entry[Part], Part);
9643}
9644
9645void VPInterleaveRecipe::execute(VPTransformState &State) {
9646 assert(!State.Instance && "Interleave group being replicated.")((void)0);
9647 State.ILV->vectorizeInterleaveGroup(IG, definedValues(), State, getAddr(),
9648 getStoredValues(), getMask());
9649}
9650
9651void VPReductionRecipe::execute(VPTransformState &State) {
9652 assert(!State.Instance && "Reduction being replicated.")((void)0);
9653 Value *PrevInChain = State.get(getChainOp(), 0);
9654 for (unsigned Part = 0; Part < State.UF; ++Part) {
9655 RecurKind Kind = RdxDesc->getRecurrenceKind();
9656 bool IsOrdered = State.ILV->useOrderedReductions(*RdxDesc);
9657 Value *NewVecOp = State.get(getVecOp(), Part);
9658 if (VPValue *Cond = getCondOp()) {
9659 Value *NewCond = State.get(Cond, Part);
9660 VectorType *VecTy = cast<VectorType>(NewVecOp->getType());
9661 Constant *Iden = RecurrenceDescriptor::getRecurrenceIdentity(
9662 Kind, VecTy->getElementType(), RdxDesc->getFastMathFlags());
9663 Constant *IdenVec =
9664 ConstantVector::getSplat(VecTy->getElementCount(), Iden);
9665 Value *Select = State.Builder.CreateSelect(NewCond, NewVecOp, IdenVec);
9666 NewVecOp = Select;
9667 }
9668 Value *NewRed;
9669 Value *NextInChain;
9670 if (IsOrdered) {
9671 if (State.VF.isVector())
9672 NewRed = createOrderedReduction(State.Builder, *RdxDesc, NewVecOp,
9673 PrevInChain);
9674 else
9675 NewRed = State.Builder.CreateBinOp(
9676 (Instruction::BinaryOps)getUnderlyingInstr()->getOpcode(),
9677 PrevInChain, NewVecOp);
9678 PrevInChain = NewRed;
9679 } else {
9680 PrevInChain = State.get(getChainOp(), Part);
9681 NewRed = createTargetReduction(State.Builder, TTI, *RdxDesc, NewVecOp);
9682 }
9683 if (RecurrenceDescriptor::isMinMaxRecurrenceKind(Kind)) {
9684 NextInChain =
9685 createMinMaxOp(State.Builder, RdxDesc->getRecurrenceKind(),
9686 NewRed, PrevInChain);
9687 } else if (IsOrdered)
9688 NextInChain = NewRed;
9689 else {
9690 NextInChain = State.Builder.CreateBinOp(
9691 (Instruction::BinaryOps)getUnderlyingInstr()->getOpcode(), NewRed,
9692 PrevInChain);
9693 }
9694 State.set(this, NextInChain, Part);
9695 }
9696}
9697
9698void VPReplicateRecipe::execute(VPTransformState &State) {
9699 if (State.Instance) { // Generate a single instance.
9700 assert(!State.VF.isScalable() && "Can't scalarize a scalable vector")((void)0);
9701 State.ILV->scalarizeInstruction(getUnderlyingInstr(), this, *this,
9702 *State.Instance, IsPredicated, State);
9703 // Insert scalar instance packing it into a vector.
9704 if (AlsoPack && State.VF.isVector()) {
9705 // If we're constructing lane 0, initialize to start from poison.
9706 if (State.Instance->Lane.isFirstLane()) {
9707 assert(!State.VF.isScalable() && "VF is assumed to be non scalable.")((void)0);
9708 Value *Poison = PoisonValue::get(
9709 VectorType::get(getUnderlyingValue()->getType(), State.VF));
9710 State.set(this, Poison, State.Instance->Part);
9711 }
9712 State.ILV->packScalarIntoVectorValue(this, *State.Instance, State);
9713 }
9714 return;
9715 }
9716
9717 // Generate scalar instances for all VF lanes of all UF parts, unless the
9718 // instruction is uniform inwhich case generate only the first lane for each
9719 // of the UF parts.
9720 unsigned EndLane = IsUniform ? 1 : State.VF.getKnownMinValue();
9721 assert((!State.VF.isScalable() || IsUniform) &&((void)0)
9722 "Can't scalarize a scalable vector")((void)0);
9723 for (unsigned Part = 0; Part < State.UF; ++Part)
9724 for (unsigned Lane = 0; Lane < EndLane; ++Lane)
9725 State.ILV->scalarizeInstruction(getUnderlyingInstr(), this, *this,
9726 VPIteration(Part, Lane), IsPredicated,
9727 State);
9728}
9729
9730void VPBranchOnMaskRecipe::execute(VPTransformState &State) {
9731 assert(State.Instance && "Branch on Mask works only on single instance.")((void)0);
9732
9733 unsigned Part = State.Instance->Part;
9734 unsigned Lane = State.Instance->Lane.getKnownLane();
9735
9736 Value *ConditionBit = nullptr;
9737 VPValue *BlockInMask = getMask();
9738 if (BlockInMask) {
9739 ConditionBit = State.get(BlockInMask, Part);
9740 if (ConditionBit->getType()->isVectorTy())
9741 ConditionBit = State.Builder.CreateExtractElement(
9742 ConditionBit, State.Builder.getInt32(Lane));
9743 } else // Block in mask is all-one.
9744 ConditionBit = State.Builder.getTrue();
9745
9746 // Replace the temporary unreachable terminator with a new conditional branch,
9747 // whose two destinations will be set later when they are created.
9748 auto *CurrentTerminator = State.CFG.PrevBB->getTerminator();
9749 assert(isa<UnreachableInst>(CurrentTerminator) &&((void)0)
9750 "Expected to replace unreachable terminator with conditional branch.")((void)0);
9751 auto *CondBr = BranchInst::Create(State.CFG.PrevBB, nullptr, ConditionBit);
9752 CondBr->setSuccessor(0, nullptr);
9753 ReplaceInstWithInst(CurrentTerminator, CondBr);
9754}
9755
9756void VPPredInstPHIRecipe::execute(VPTransformState &State) {
9757 assert(State.Instance && "Predicated instruction PHI works per instance.")((void)0);
9758 Instruction *ScalarPredInst =
9759 cast<Instruction>(State.get(getOperand(0), *State.Instance));
9760 BasicBlock *PredicatedBB = ScalarPredInst->getParent();
9761 BasicBlock *PredicatingBB = PredicatedBB->getSinglePredecessor();
9762 assert(PredicatingBB && "Predicated block has no single predecessor.")((void)0);
9763 assert(isa<VPReplicateRecipe>(getOperand(0)) &&((void)0)
9764 "operand must be VPReplicateRecipe")((void)0);
9765
9766 // By current pack/unpack logic we need to generate only a single phi node: if
9767 // a vector value for the predicated instruction exists at this point it means
9768 // the instruction has vector users only, and a phi for the vector value is
9769 // needed. In this case the recipe of the predicated instruction is marked to
9770 // also do that packing, thereby "hoisting" the insert-element sequence.
9771 // Otherwise, a phi node for the scalar value is needed.
9772 unsigned Part = State.Instance->Part;
9773 if (State.hasVectorValue(getOperand(0), Part)) {
9774 Value *VectorValue = State.get(getOperand(0), Part);
9775 InsertElementInst *IEI = cast<InsertElementInst>(VectorValue);
9776 PHINode *VPhi = State.Builder.CreatePHI(IEI->getType(), 2);
9777 VPhi->addIncoming(IEI->getOperand(0), PredicatingBB); // Unmodified vector.
9778 VPhi->addIncoming(IEI, PredicatedBB); // New vector with inserted element.
9779 if (State.hasVectorValue(this, Part))
9780 State.reset(this, VPhi, Part);
9781 else
9782 State.set(this, VPhi, Part);
9783 // NOTE: Currently we need to update the value of the operand, so the next
9784 // predicated iteration inserts its generated value in the correct vector.
9785 State.reset(getOperand(0), VPhi, Part);
9786 } else {
9787 Type *PredInstType = getOperand(0)->getUnderlyingValue()->getType();
9788 PHINode *Phi = State.Builder.CreatePHI(PredInstType, 2);
9789 Phi->addIncoming(PoisonValue::get(ScalarPredInst->getType()),
9790 PredicatingBB);
9791 Phi->addIncoming(ScalarPredInst, PredicatedBB);
9792 if (State.hasScalarValue(this, *State.Instance))
9793 State.reset(this, Phi, *State.Instance);
9794 else
9795 State.set(this, Phi, *State.Instance);
9796 // NOTE: Currently we need to update the value of the operand, so the next
9797 // predicated iteration inserts its generated value in the correct vector.
9798 State.reset(getOperand(0), Phi, *State.Instance);
9799 }
9800}
9801
9802void VPWidenMemoryInstructionRecipe::execute(VPTransformState &State) {
9803 VPValue *StoredValue = isStore() ? getStoredValue() : nullptr;
9804 State.ILV->vectorizeMemoryInstruction(
9805 &Ingredient, State, StoredValue ? nullptr : getVPSingleValue(), getAddr(),
9806 StoredValue, getMask());
9807}
9808
9809// Determine how to lower the scalar epilogue, which depends on 1) optimising
9810// for minimum code-size, 2) predicate compiler options, 3) loop hints forcing
9811// predication, and 4) a TTI hook that analyses whether the loop is suitable
9812// for predication.
9813static ScalarEpilogueLowering getScalarEpilogueLowering(
9814 Function *F, Loop *L, LoopVectorizeHints &Hints, ProfileSummaryInfo *PSI,
9815 BlockFrequencyInfo *BFI, TargetTransformInfo *TTI, TargetLibraryInfo *TLI,
9816 AssumptionCache *AC, LoopInfo *LI, ScalarEvolution *SE, DominatorTree *DT,
9817 LoopVectorizationLegality &LVL) {
9818 // 1) OptSize takes precedence over all other options, i.e. if this is set,
9819 // don't look at hints or options, and don't request a scalar epilogue.
9820 // (For PGSO, as shouldOptimizeForSize isn't currently accessible from
9821 // LoopAccessInfo (due to code dependency and not being able to reliably get
9822 // PSI/BFI from a loop analysis under NPM), we cannot suppress the collection
9823 // of strides in LoopAccessInfo::analyzeLoop() and vectorize without
9824 // versioning when the vectorization is forced, unlike hasOptSize. So revert
9825 // back to the old way and vectorize with versioning when forced. See D81345.)
9826 if (F->hasOptSize() || (llvm::shouldOptimizeForSize(L->getHeader(), PSI, BFI,
9827 PGSOQueryType::IRPass) &&
9828 Hints.getForce() != LoopVectorizeHints::FK_Enabled))
9829 return CM_ScalarEpilogueNotAllowedOptSize;
9830
9831 // 2) If set, obey the directives
9832 if (PreferPredicateOverEpilogue.getNumOccurrences()) {
9833 switch (PreferPredicateOverEpilogue) {
9834 case PreferPredicateTy::ScalarEpilogue:
9835 return CM_ScalarEpilogueAllowed;
9836 case PreferPredicateTy::PredicateElseScalarEpilogue:
9837 return CM_ScalarEpilogueNotNeededUsePredicate;
9838 case PreferPredicateTy::PredicateOrDontVectorize:
9839 return CM_ScalarEpilogueNotAllowedUsePredicate;
9840 };
9841 }
9842
9843 // 3) If set, obey the hints
9844 switch (Hints.getPredicate()) {
9845 case LoopVectorizeHints::FK_Enabled:
9846 return CM_ScalarEpilogueNotNeededUsePredicate;
9847 case LoopVectorizeHints::FK_Disabled:
9848 return CM_ScalarEpilogueAllowed;
9849 };
9850
9851 // 4) if the TTI hook indicates this is profitable, request predication.
9852 if (TTI->preferPredicateOverEpilogue(L, LI, *SE, *AC, TLI, DT,
9853 LVL.getLAI()))
9854 return CM_ScalarEpilogueNotNeededUsePredicate;
9855
9856 return CM_ScalarEpilogueAllowed;
9857}
9858
9859Value *VPTransformState::get(VPValue *Def, unsigned Part) {
9860 // If Values have been set for this Def return the one relevant for \p Part.
9861 if (hasVectorValue(Def, Part))
9862 return Data.PerPartOutput[Def][Part];
9863
9864 if (!hasScalarValue(Def, {Part, 0})) {
9865 Value *IRV = Def->getLiveInIRValue();
9866 Value *B = ILV->getBroadcastInstrs(IRV);
9867 set(Def, B, Part);
9868 return B;
9869 }
9870
9871 Value *ScalarValue = get(Def, {Part, 0});
9872 // If we aren't vectorizing, we can just copy the scalar map values over
9873 // to the vector map.
9874 if (VF.isScalar()) {
9875 set(Def, ScalarValue, Part);
9876 return ScalarValue;
9877 }
9878
9879 auto *RepR = dyn_cast<VPReplicateRecipe>(Def);
9880 bool IsUniform = RepR && RepR->isUniform();
9881
9882 unsigned LastLane = IsUniform ? 0 : VF.getKnownMinValue() - 1;
9883 // Check if there is a scalar value for the selected lane.
9884 if (!hasScalarValue(Def, {Part, LastLane})) {
9885 // At the moment, VPWidenIntOrFpInductionRecipes can also be uniform.
9886 assert(isa<VPWidenIntOrFpInductionRecipe>(Def->getDef()) &&((void)0)
9887 "unexpected recipe found to be invariant")((void)0);
9888 IsUniform = true;
9889 LastLane = 0;
9890 }
9891
9892 auto *LastInst = cast<Instruction>(get(Def, {Part, LastLane}));
9893 // Set the insert point after the last scalarized instruction or after the
9894 // last PHI, if LastInst is a PHI. This ensures the insertelement sequence
9895 // will directly follow the scalar definitions.
9896 auto OldIP = Builder.saveIP();
9897 auto NewIP =
9898 isa<PHINode>(LastInst)
9899 ? BasicBlock::iterator(LastInst->getParent()->getFirstNonPHI())
9900 : std::next(BasicBlock::iterator(LastInst));
9901 Builder.SetInsertPoint(&*NewIP);
9902
9903 // However, if we are vectorizing, we need to construct the vector values.
9904 // If the value is known to be uniform after vectorization, we can just
9905 // broadcast the scalar value corresponding to lane zero for each unroll
9906 // iteration. Otherwise, we construct the vector values using
9907 // insertelement instructions. Since the resulting vectors are stored in
9908 // State, we will only generate the insertelements once.
9909 Value *VectorValue = nullptr;
9910 if (IsUniform) {
9911 VectorValue = ILV->getBroadcastInstrs(ScalarValue);
9912 set(Def, VectorValue, Part);
9913 } else {
9914 // Initialize packing with insertelements to start from undef.
9915 assert(!VF.isScalable() && "VF is assumed to be non scalable.")((void)0);
9916 Value *Undef = PoisonValue::get(VectorType::get(LastInst->getType(), VF));
9917 set(Def, Undef, Part);
9918 for (unsigned Lane = 0; Lane < VF.getKnownMinValue(); ++Lane)
9919 ILV->packScalarIntoVectorValue(Def, {Part, Lane}, *this);
9920 VectorValue = get(Def, Part);
9921 }
9922 Builder.restoreIP(OldIP);
9923 return VectorValue;
9924}
9925
9926// Process the loop in the VPlan-native vectorization path. This path builds
9927// VPlan upfront in the vectorization pipeline, which allows to apply
9928// VPlan-to-VPlan transformations from the very beginning without modifying the
9929// input LLVM IR.
9930static bool processLoopInVPlanNativePath(
9931 Loop *L, PredicatedScalarEvolution &PSE, LoopInfo *LI, DominatorTree *DT,
9932 LoopVectorizationLegality *LVL, TargetTransformInfo *TTI,
9933 TargetLibraryInfo *TLI, DemandedBits *DB, AssumptionCache *AC,
9934 OptimizationRemarkEmitter *ORE, BlockFrequencyInfo *BFI,
9935 ProfileSummaryInfo *PSI, LoopVectorizeHints &Hints,
9936 LoopVectorizationRequirements &Requirements) {
9937
9938 if (isa<SCEVCouldNotCompute>(PSE.getBackedgeTakenCount())) {
10
Assuming the object is not a 'SCEVCouldNotCompute'
11
Taking false branch
9939 LLVM_DEBUG(dbgs() << "LV: cannot compute the outer-loop trip count\n")do { } while (false);
9940 return false;
9941 }
9942 assert(EnableVPlanNativePath && "VPlan-native path is disabled.")((void)0);
9943 Function *F = L->getHeader()->getParent();
9944 InterleavedAccessInfo IAI(PSE, L, DT, LI, LVL->getLAI());
9945
9946 ScalarEpilogueLowering SEL = getScalarEpilogueLowering(
9947 F, L, Hints, PSI, BFI, TTI, TLI, AC, LI, PSE.getSE(), DT, *LVL);
9948
9949 LoopVectorizationCostModel CM(SEL, L, PSE, LI, LVL, *TTI, TLI, DB, AC, ORE, F,
9950 &Hints, IAI);
9951 // Use the planner for outer loop vectorization.
9952 // TODO: CM is not used at this point inside the planner. Turn CM into an
9953 // optional argument if we don't need it in the future.
9954 LoopVectorizationPlanner LVP(L, LI, TLI, TTI, LVL, CM, IAI, PSE, Hints,
9955 Requirements, ORE);
9956
9957 // Get user vectorization factor.
9958 ElementCount UserVF = Hints.getWidth();
9959
9960 CM.collectElementTypesForWidening();
9961
9962 // Plan how to best vectorize, return the best VF and its cost.
9963 const VectorizationFactor VF = LVP.planInVPlanNativePath(UserVF);
9964
9965 // If we are stress testing VPlan builds, do not attempt to generate vector
9966 // code. Masked vector code generation support will follow soon.
9967 // Also, do not attempt to vectorize if no vector code will be produced.
9968 if (VPlanBuildStressTest || EnableVPlanPredication ||
12
Assuming the condition is false
13
Taking false branch
9969 VectorizationFactor::Disabled() == VF)
9970 return false;
9971
9972 LVP.setBestPlan(VF.Width, 1);
9973
9974 {
9975 GeneratedRTChecks Checks(*PSE.getSE(), DT, LI,
9976 F->getParent()->getDataLayout());
9977 InnerLoopVectorizer LB(L, PSE, LI, DT, TLI, TTI, AC, ORE, VF.Width, 1, LVL,
9978 &CM, BFI, PSI, Checks);
9979 LLVM_DEBUG(dbgs() << "Vectorizing outer loop in \""do { } while (false)
14
Loop condition is false. Exiting loop
9980 << L->getHeader()->getParent()->getName() << "\"\n")do { } while (false);
9981 LVP.executePlan(LB, DT);
15
Calling 'LoopVectorizationPlanner::executePlan'
9982 }
9983
9984 // Mark the loop as already vectorized to avoid vectorizing again.
9985 Hints.setAlreadyVectorized();
9986 assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()))((void)0);
9987 return true;
9988}
9989
9990// Emit a remark if there are stores to floats that required a floating point
9991// extension. If the vectorized loop was generated with floating point there
9992// will be a performance penalty from the conversion overhead and the change in
9993// the vector width.
9994static void checkMixedPrecision(Loop *L, OptimizationRemarkEmitter *ORE) {
9995 SmallVector<Instruction *, 4> Worklist;
9996 for (BasicBlock *BB : L->getBlocks()) {
9997 for (Instruction &Inst : *BB) {
9998 if (auto *S = dyn_cast<StoreInst>(&Inst)) {
9999 if (S->getValueOperand()->getType()->isFloatTy())
10000 Worklist.push_back(S);
10001 }
10002 }
10003 }
10004
10005 // Traverse the floating point stores upwards searching, for floating point
10006 // conversions.
10007 SmallPtrSet<const Instruction *, 4> Visited;
10008 SmallPtrSet<const Instruction *, 4> EmittedRemark;
10009 while (!Worklist.empty()) {
10010 auto *I = Worklist.pop_back_val();
10011 if (!L->contains(I))
10012 continue;
10013 if (!Visited.insert(I).second)
10014 continue;
10015
10016 // Emit a remark if the floating point store required a floating
10017 // point conversion.
10018 // TODO: More work could be done to identify the root cause such as a
10019 // constant or a function return type and point the user to it.
10020 if (isa<FPExtInst>(I) && EmittedRemark.insert(I).second)
10021 ORE->emit([&]() {
10022 return OptimizationRemarkAnalysis(LV_NAME"loop-vectorize", "VectorMixedPrecision",
10023 I->getDebugLoc(), L->getHeader())
10024 << "floating point conversion changes vector width. "
10025 << "Mixed floating point precision requires an up/down "
10026 << "cast that will negatively impact performance.";
10027 });
10028
10029 for (Use &Op : I->operands())
10030 if (auto *OpI = dyn_cast<Instruction>(Op))
10031 Worklist.push_back(OpI);
10032 }
10033}
10034
10035LoopVectorizePass::LoopVectorizePass(LoopVectorizeOptions Opts)
10036 : InterleaveOnlyWhenForced(Opts.InterleaveOnlyWhenForced ||
10037 !EnableLoopInterleaving),
10038 VectorizeOnlyWhenForced(Opts.VectorizeOnlyWhenForced ||
10039 !EnableLoopVectorization) {}
10040
10041bool LoopVectorizePass::processLoop(Loop *L) {
10042 assert((EnableVPlanNativePath || L->isInnermost()) &&((void)0)
10043 "VPlan-native path is not enabled. Only process inner loops.")((void)0);
10044
10045#ifndef NDEBUG1
10046 const std::string DebugLocStr = getDebugLocString(L);
10047#endif /* NDEBUG */
10048
10049 LLVM_DEBUG(dbgs() << "\nLV: Checking a loop in \""do { } while (false)
1
Loop condition is false. Exiting loop
10050 << L->getHeader()->getParent()->getName() << "\" from "do { } while (false)
10051 << DebugLocStr << "\n")do { } while (false);
10052
10053 LoopVectorizeHints Hints(L, InterleaveOnlyWhenForced, *ORE);
10054
10055 LLVM_DEBUG(do { } while (false)
2
Loop condition is false. Exiting loop
10056 dbgs() << "LV: Loop hints:"do { } while (false)
10057 << " force="do { } while (false)
10058 << (Hints.getForce() == LoopVectorizeHints::FK_Disableddo { } while (false)
10059 ? "disabled"do { } while (false)
10060 : (Hints.getForce() == LoopVectorizeHints::FK_Enableddo { } while (false)
10061 ? "enabled"do { } while (false)
10062 : "?"))do { } while (false)
10063 << " width=" << Hints.getWidth()do { } while (false)
10064 << " interleave=" << Hints.getInterleave() << "\n")do { } while (false);
10065
10066 // Function containing loop
10067 Function *F = L->getHeader()->getParent();
10068
10069 // Looking at the diagnostic output is the only way to determine if a loop
10070 // was vectorized (other than looking at the IR or machine code), so it
10071 // is important to generate an optimization remark for each loop. Most of
10072 // these messages are generated as OptimizationRemarkAnalysis. Remarks
10073 // generated as OptimizationRemark and OptimizationRemarkMissed are
10074 // less verbose reporting vectorized loops and unvectorized loops that may
10075 // benefit from vectorization, respectively.
10076
10077 if (!Hints.allowVectorization(F, L, VectorizeOnlyWhenForced)) {
3
Assuming the condition is false
4
Taking false branch
10078 LLVM_DEBUG(dbgs() << "LV: Loop hints prevent vectorization.\n")do { } while (false);
10079 return false;
10080 }
10081
10082 PredicatedScalarEvolution PSE(*SE, *L);
10083
10084 // Check if it is legal to vectorize the loop.
10085 LoopVectorizationRequirements Requirements;
10086 LoopVectorizationLegality LVL(L, PSE, DT, TTI, TLI, AA, F, GetLAA, LI, ORE,
10087 &Requirements, &Hints, DB, AC, BFI, PSI);
10088 if (!LVL.canVectorize(EnableVPlanNativePath)) {
5
Assuming the condition is false
6
Taking false branch
10089 LLVM_DEBUG(dbgs() << "LV: Not vectorizing: Cannot prove legality.\n")do { } while (false);
10090 Hints.emitRemarkWithHints();
10091 return false;
10092 }
10093
10094 // Check the function attributes and profiles to find out if this function
10095 // should be optimized for size.
10096 ScalarEpilogueLowering SEL = getScalarEpilogueLowering(
10097 F, L, Hints, PSI, BFI, TTI, TLI, AC, LI, PSE.getSE(), DT, LVL);
10098
10099 // Entrance to the VPlan-native vectorization path. Outer loops are processed
10100 // here. They may require CFG and instruction level transformations before
10101 // even evaluating whether vectorization is profitable. Since we cannot modify
10102 // the incoming IR, we need to build VPlan upfront in the vectorization
10103 // pipeline.
10104 if (!L->isInnermost())
7
Assuming the condition is true
8
Taking true branch
10105 return processLoopInVPlanNativePath(L, PSE, LI, DT, &LVL, TTI, TLI, DB, AC,
9
Calling 'processLoopInVPlanNativePath'
10106 ORE, BFI, PSI, Hints, Requirements);
10107
10108 assert(L->isInnermost() && "Inner loop expected.")((void)0);
10109
10110 // Check the loop for a trip count threshold: vectorize loops with a tiny trip
10111 // count by optimizing for size, to minimize overheads.
10112 auto ExpectedTC = getSmallBestKnownTC(*SE, L);
10113 if (ExpectedTC && *ExpectedTC < TinyTripCountVectorThreshold) {
10114 LLVM_DEBUG(dbgs() << "LV: Found a loop with a very small trip count. "do { } while (false)
10115 << "This loop is worth vectorizing only if no scalar "do { } while (false)
10116 << "iteration overheads are incurred.")do { } while (false);
10117 if (Hints.getForce() == LoopVectorizeHints::FK_Enabled)
10118 LLVM_DEBUG(dbgs() << " But vectorizing was explicitly forced.\n")do { } while (false);
10119 else {
10120 LLVM_DEBUG(dbgs() << "\n")do { } while (false);
10121 SEL = CM_ScalarEpilogueNotAllowedLowTripLoop;
10122 }
10123 }
10124
10125 // Check the function attributes to see if implicit floats are allowed.
10126 // FIXME: This check doesn't seem possibly correct -- what if the loop is
10127 // an integer loop and the vector instructions selected are purely integer
10128 // vector instructions?
10129 if (F->hasFnAttribute(Attribute::NoImplicitFloat)) {
10130 reportVectorizationFailure(
10131 "Can't vectorize when the NoImplicitFloat attribute is used",
10132 "loop not vectorized due to NoImplicitFloat attribute",
10133 "NoImplicitFloat", ORE, L);
10134 Hints.emitRemarkWithHints();
10135 return false;
10136 }
10137
10138 // Check if the target supports potentially unsafe FP vectorization.
10139 // FIXME: Add a check for the type of safety issue (denormal, signaling)
10140 // for the target we're vectorizing for, to make sure none of the
10141 // additional fp-math flags can help.
10142 if (Hints.isPotentiallyUnsafe() &&
10143 TTI->isFPVectorizationPotentiallyUnsafe()) {
10144 reportVectorizationFailure(
10145 "Potentially unsafe FP op prevents vectorization",
10146 "loop not vectorized due to unsafe FP support.",
10147 "UnsafeFP", ORE, L);
10148 Hints.emitRemarkWithHints();
10149 return false;
10150 }
10151
10152 if (!LVL.canVectorizeFPMath(EnableStrictReductions)) {
10153 ORE->emit([&]() {
10154 auto *ExactFPMathInst = Requirements.getExactFPInst();
10155 return OptimizationRemarkAnalysisFPCommute(DEBUG_TYPE"loop-vectorize", "CantReorderFPOps",
10156 ExactFPMathInst->getDebugLoc(),
10157 ExactFPMathInst->getParent())
10158 << "loop not vectorized: cannot prove it is safe to reorder "
10159 "floating-point operations";
10160 });
10161 LLVM_DEBUG(dbgs() << "LV: loop not vectorized: cannot prove it is safe to "do { } while (false)
10162 "reorder floating-point operations\n")do { } while (false);
10163 Hints.emitRemarkWithHints();
10164 return false;
10165 }
10166
10167 bool UseInterleaved = TTI->enableInterleavedAccessVectorization();
10168 InterleavedAccessInfo IAI(PSE, L, DT, LI, LVL.getLAI());
10169
10170 // If an override option has been passed in for interleaved accesses, use it.
10171 if (EnableInterleavedMemAccesses.getNumOccurrences() > 0)
10172 UseInterleaved = EnableInterleavedMemAccesses;
10173
10174 // Analyze interleaved memory accesses.
10175 if (UseInterleaved) {
10176 IAI.analyzeInterleaving(useMaskedInterleavedAccesses(*TTI));
10177 }
10178
10179 // Use the cost model.
10180 LoopVectorizationCostModel CM(SEL, L, PSE, LI, &LVL, *TTI, TLI, DB, AC, ORE,
10181 F, &Hints, IAI);
10182 CM.collectValuesToIgnore();
10183 CM.collectElementTypesForWidening();
10184
10185 // Use the planner for vectorization.
10186 LoopVectorizationPlanner LVP(L, LI, TLI, TTI, &LVL, CM, IAI, PSE, Hints,
10187 Requirements, ORE);
10188
10189 // Get user vectorization factor and interleave count.
10190 ElementCount UserVF = Hints.getWidth();
10191 unsigned UserIC = Hints.getInterleave();
10192
10193 // Plan how to best vectorize, return the best VF and its cost.
10194 Optional<VectorizationFactor> MaybeVF = LVP.plan(UserVF, UserIC);
10195
10196 VectorizationFactor VF = VectorizationFactor::Disabled();
10197 unsigned IC = 1;
10198
10199 if (MaybeVF) {
10200 VF = *MaybeVF;
10201 // Select the interleave count.
10202 IC = CM.selectInterleaveCount(VF.Width, *VF.Cost.getValue());
10203 }
10204
10205 // Identify the diagnostic messages that should be produced.
10206 std::pair<StringRef, std::string> VecDiagMsg, IntDiagMsg;
10207 bool VectorizeLoop = true, InterleaveLoop = true;
10208 if (VF.Width.isScalar()) {
10209 LLVM_DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial.\n")do { } while (false);
10210 VecDiagMsg = std::make_pair(
10211 "VectorizationNotBeneficial",
10212 "the cost-model indicates that vectorization is not beneficial");
10213 VectorizeLoop = false;
10214 }
10215
10216 if (!MaybeVF && UserIC > 1) {
10217 // Tell the user interleaving was avoided up-front, despite being explicitly
10218 // requested.
10219 LLVM_DEBUG(dbgs() << "LV: Ignoring UserIC, because vectorization and "do { } while (false)
10220 "interleaving should be avoided up front\n")do { } while (false);
10221 IntDiagMsg = std::make_pair(
10222 "InterleavingAvoided",
10223 "Ignoring UserIC, because interleaving was avoided up front");
10224 InterleaveLoop = false;
10225 } else if (IC == 1 && UserIC <= 1) {
10226 // Tell the user interleaving is not beneficial.
10227 LLVM_DEBUG(dbgs() << "LV: Interleaving is not beneficial.\n")do { } while (false);
10228 IntDiagMsg = std::make_pair(
10229 "InterleavingNotBeneficial",
10230 "the cost-model indicates that interleaving is not beneficial");
10231 InterleaveLoop = false;
10232 if (UserIC == 1) {
10233 IntDiagMsg.first = "InterleavingNotBeneficialAndDisabled";
10234 IntDiagMsg.second +=
10235 " and is explicitly disabled or interleave count is set to 1";
10236 }
10237 } else if (IC > 1 && UserIC == 1) {
10238 // Tell the user interleaving is beneficial, but it explicitly disabled.
10239 LLVM_DEBUG(do { } while (false)
10240 dbgs() << "LV: Interleaving is beneficial but is explicitly disabled.")do { } while (false);
10241 IntDiagMsg = std::make_pair(
10242 "InterleavingBeneficialButDisabled",
10243 "the cost-model indicates that interleaving is beneficial "
10244 "but is explicitly disabled or interleave count is set to 1");
10245 InterleaveLoop = false;
10246 }
10247
10248 // Override IC if user provided an interleave count.
10249 IC = UserIC > 0 ? UserIC : IC;
10250
10251 // Emit diagnostic messages, if any.
10252 const char *VAPassName = Hints.vectorizeAnalysisPassName();
10253 if (!VectorizeLoop && !InterleaveLoop) {
10254 // Do not vectorize or interleaving the loop.
10255 ORE->emit([&]() {
10256 return OptimizationRemarkMissed(VAPassName, VecDiagMsg.first,
10257 L->getStartLoc(), L->getHeader())
10258 << VecDiagMsg.second;
10259 });
10260 ORE->emit([&]() {
10261 return OptimizationRemarkMissed(LV_NAME"loop-vectorize", IntDiagMsg.first,
10262 L->getStartLoc(), L->getHeader())
10263 << IntDiagMsg.second;
10264 });
10265 return false;
10266 } else if (!VectorizeLoop && InterleaveLoop) {
10267 LLVM_DEBUG(dbgs() << "LV: Interleave Count is " << IC << '\n')do { } while (false);
10268 ORE->emit([&]() {
10269 return OptimizationRemarkAnalysis(VAPassName, VecDiagMsg.first,
10270 L->getStartLoc(), L->getHeader())
10271 << VecDiagMsg.second;
10272 });
10273 } else if (VectorizeLoop && !InterleaveLoop) {
10274 LLVM_DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Widthdo { } while (false)
10275 << ") in " << DebugLocStr << '\n')do { } while (false);
10276 ORE->emit([&]() {
10277 return OptimizationRemarkAnalysis(LV_NAME"loop-vectorize", IntDiagMsg.first,
10278 L->getStartLoc(), L->getHeader())
10279 << IntDiagMsg.second;
10280 });
10281 } else if (VectorizeLoop && InterleaveLoop) {
10282 LLVM_DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Widthdo { } while (false)
10283 << ") in " << DebugLocStr << '\n')do { } while (false);
10284 LLVM_DEBUG(dbgs() << "LV: Interleave Count is " << IC << '\n')do { } while (false);
10285 }
10286
10287 bool DisableRuntimeUnroll = false;
10288 MDNode *OrigLoopID = L->getLoopID();
10289 {
10290 // Optimistically generate runtime checks. Drop them if they turn out to not
10291 // be profitable. Limit the scope of Checks, so the cleanup happens
10292 // immediately after vector codegeneration is done.
10293 GeneratedRTChecks Checks(*PSE.getSE(), DT, LI,
10294 F->getParent()->getDataLayout());
10295 if (!VF.Width.isScalar() || IC > 1)
10296 Checks.Create(L, *LVL.getLAI(), PSE.getUnionPredicate());
10297 LVP.setBestPlan(VF.Width, IC);
10298
10299 using namespace ore;
10300 if (!VectorizeLoop) {
10301 assert(IC > 1 && "interleave count should not be 1 or 0")((void)0);
10302 // If we decided that it is not legal to vectorize the loop, then
10303 // interleave it.
10304 InnerLoopUnroller Unroller(L, PSE, LI, DT, TLI, TTI, AC, ORE, IC, &LVL,
10305 &CM, BFI, PSI, Checks);
10306 LVP.executePlan(Unroller, DT);
10307
10308 ORE->emit([&]() {
10309 return OptimizationRemark(LV_NAME"loop-vectorize", "Interleaved", L->getStartLoc(),
10310 L->getHeader())
10311 << "interleaved loop (interleaved count: "
10312 << NV("InterleaveCount", IC) << ")";
10313 });
10314 } else {
10315 // If we decided that it is *legal* to vectorize the loop, then do it.
10316
10317 // Consider vectorizing the epilogue too if it's profitable.
10318 VectorizationFactor EpilogueVF =
10319 CM.selectEpilogueVectorizationFactor(VF.Width, LVP);
10320 if (EpilogueVF.Width.isVector()) {
10321
10322 // The first pass vectorizes the main loop and creates a scalar epilogue
10323 // to be vectorized by executing the plan (potentially with a different
10324 // factor) again shortly afterwards.
10325 EpilogueLoopVectorizationInfo EPI(VF.Width.getKnownMinValue(), IC,
10326 EpilogueVF.Width.getKnownMinValue(),
10327 1);
10328 EpilogueVectorizerMainLoop MainILV(L, PSE, LI, DT, TLI, TTI, AC, ORE,
10329 EPI, &LVL, &CM, BFI, PSI, Checks);
10330
10331 LVP.setBestPlan(EPI.MainLoopVF, EPI.MainLoopUF);
10332 LVP.executePlan(MainILV, DT);
10333 ++LoopsVectorized;
10334
10335 simplifyLoop(L, DT, LI, SE, AC, nullptr, false /* PreserveLCSSA */);
10336 formLCSSARecursively(*L, *DT, LI, SE);
10337
10338 // Second pass vectorizes the epilogue and adjusts the control flow
10339 // edges from the first pass.
10340 LVP.setBestPlan(EPI.EpilogueVF, EPI.EpilogueUF);
10341 EPI.MainLoopVF = EPI.EpilogueVF;
10342 EPI.MainLoopUF = EPI.EpilogueUF;
10343 EpilogueVectorizerEpilogueLoop EpilogILV(L, PSE, LI, DT, TLI, TTI, AC,
10344 ORE, EPI, &LVL, &CM, BFI, PSI,
10345 Checks);
10346 LVP.executePlan(EpilogILV, DT);
10347 ++LoopsEpilogueVectorized;
10348
10349 if (!MainILV.areSafetyChecksAdded())
10350 DisableRuntimeUnroll = true;
10351 } else {
10352 InnerLoopVectorizer LB(L, PSE, LI, DT, TLI, TTI, AC, ORE, VF.Width, IC,
10353 &LVL, &CM, BFI, PSI, Checks);
10354 LVP.executePlan(LB, DT);
10355 ++LoopsVectorized;
10356
10357 // Add metadata to disable runtime unrolling a scalar loop when there
10358 // are no runtime checks about strides and memory. A scalar loop that is
10359 // rarely used is not worth unrolling.
10360 if (!LB.areSafetyChecksAdded())
10361 DisableRuntimeUnroll = true;
10362 }
10363 // Report the vectorization decision.
10364 ORE->emit([&]() {
10365 return OptimizationRemark(LV_NAME"loop-vectorize", "Vectorized", L->getStartLoc(),
10366 L->getHeader())
10367 << "vectorized loop (vectorization width: "
10368 << NV("VectorizationFactor", VF.Width)
10369 << ", interleaved count: " << NV("InterleaveCount", IC) << ")";
10370 });
10371 }
10372
10373 if (ORE->allowExtraAnalysis(LV_NAME"loop-vectorize"))
10374 checkMixedPrecision(L, ORE);
10375 }
10376
10377 Optional<MDNode *> RemainderLoopID =
10378 makeFollowupLoopID(OrigLoopID, {LLVMLoopVectorizeFollowupAll,
10379 LLVMLoopVectorizeFollowupEpilogue});
10380 if (RemainderLoopID.hasValue()) {
10381 L->setLoopID(RemainderLoopID.getValue());
10382 } else {
10383 if (DisableRuntimeUnroll)
10384 AddRuntimeUnrollDisableMetaData(L);
10385
10386 // Mark the loop as already vectorized to avoid vectorizing again.
10387 Hints.setAlreadyVectorized();
10388 }
10389
10390 assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()))((void)0);
10391 return true;
10392}
10393
10394LoopVectorizeResult LoopVectorizePass::runImpl(
10395 Function &F, ScalarEvolution &SE_, LoopInfo &LI_, TargetTransformInfo &TTI_,
10396 DominatorTree &DT_, BlockFrequencyInfo &BFI_, TargetLibraryInfo *TLI_,
10397 DemandedBits &DB_, AAResults &AA_, AssumptionCache &AC_,
10398 std::function<const LoopAccessInfo &(Loop &)> &GetLAA_,
10399 OptimizationRemarkEmitter &ORE_, ProfileSummaryInfo *PSI_) {
10400 SE = &SE_;
10401 LI = &LI_;
10402 TTI = &TTI_;
10403 DT = &DT_;
10404 BFI = &BFI_;
10405 TLI = TLI_;
10406 AA = &AA_;
10407 AC = &AC_;
10408 GetLAA = &GetLAA_;
10409 DB = &DB_;
10410 ORE = &ORE_;
10411 PSI = PSI_;
10412
10413 // Don't attempt if
10414 // 1. the target claims to have no vector registers, and
10415 // 2. interleaving won't help ILP.
10416 //
10417 // The second condition is necessary because, even if the target has no
10418 // vector registers, loop vectorization may still enable scalar
10419 // interleaving.
10420 if (!TTI->getNumberOfRegisters(TTI->getRegisterClassForType(true)) &&
10421 TTI->getMaxInterleaveFactor(1) < 2)
10422 return LoopVectorizeResult(false, false);
10423
10424 bool Changed = false, CFGChanged = false;
10425
10426 // The vectorizer requires loops to be in simplified form.
10427 // Since simplification may add new inner loops, it has to run before the
10428 // legality and profitability checks. This means running the loop vectorizer
10429 // will simplify all loops, regardless of whether anything end up being
10430 // vectorized.
10431 for (auto &L : *LI)
10432 Changed |= CFGChanged |=
10433 simplifyLoop(L, DT, LI, SE, AC, nullptr, false /* PreserveLCSSA */);
10434
10435 // Build up a worklist of inner-loops to vectorize. This is necessary as
10436 // the act of vectorizing or partially unrolling a loop creates new loops
10437 // and can invalidate iterators across the loops.
10438 SmallVector<Loop *, 8> Worklist;
10439
10440 for (Loop *L : *LI)
10441 collectSupportedLoops(*L, LI, ORE, Worklist);
10442
10443 LoopsAnalyzed += Worklist.size();
10444
10445 // Now walk the identified inner loops.
10446 while (!Worklist.empty()) {
10447 Loop *L = Worklist.pop_back_val();
10448
10449 // For the inner loops we actually process, form LCSSA to simplify the
10450 // transform.
10451 Changed |= formLCSSARecursively(*L, *DT, LI, SE);
10452
10453 Changed |= CFGChanged |= processLoop(L);
10454 }
10455
10456 // Process each loop nest in the function.
10457 return LoopVectorizeResult(Changed, CFGChanged);
10458}
10459
10460PreservedAnalyses LoopVectorizePass::run(Function &F,
10461 FunctionAnalysisManager &AM) {
10462 auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
10463 auto &LI = AM.getResult<LoopAnalysis>(F);
10464 auto &TTI = AM.getResult<TargetIRAnalysis>(F);
10465 auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
10466 auto &BFI = AM.getResult<BlockFrequencyAnalysis>(F);
10467 auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
10468 auto &AA = AM.getResult<AAManager>(F);
10469 auto &AC = AM.getResult<AssumptionAnalysis>(F);
10470 auto &DB = AM.getResult<DemandedBitsAnalysis>(F);
10471 auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
10472 MemorySSA *MSSA = EnableMSSALoopDependency
10473 ? &AM.getResult<MemorySSAAnalysis>(F).getMSSA()
10474 : nullptr;
10475
10476 auto &LAM = AM.getResult<LoopAnalysisManagerFunctionProxy>(F).getManager();
10477 std::function<const LoopAccessInfo &(Loop &)> GetLAA =
10478 [&](Loop &L) -> const LoopAccessInfo & {
10479 LoopStandardAnalysisResults AR = {AA, AC, DT, LI, SE,
10480 TLI, TTI, nullptr, MSSA};
10481 return LAM.getResult<LoopAccessAnalysis>(L, AR);
10482 };
10483 auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
10484 ProfileSummaryInfo *PSI =
10485 MAMProxy.getCachedResult<ProfileSummaryAnalysis>(*F.getParent());
10486 LoopVectorizeResult Result =
10487 runImpl(F, SE, LI, TTI, DT, BFI, &TLI, DB, AA, AC, GetLAA, ORE, PSI);
10488 if (!Result.MadeAnyChange)
10489 return PreservedAnalyses::all();
10490 PreservedAnalyses PA;
10491
10492 // We currently do not preserve loopinfo/dominator analyses with outer loop
10493 // vectorization. Until this is addressed, mark these analyses as preserved
10494 // only for non-VPlan-native path.
10495 // TODO: Preserve Loop and Dominator analyses for VPlan-native path.
10496 if (!EnableVPlanNativePath) {
10497 PA.preserve<LoopAnalysis>();
10498 PA.preserve<DominatorTreeAnalysis>();
10499 }
10500 if (!Result.MadeCFGChange)
10501 PA.preserveSet<CFGAnalyses>();
10502 return PA;
10503}