Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support/GenericDomTree.h
Warning:line 494, column 12
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 DeadStoreElimination.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 static -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" -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 -stack-protector 2 -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/Scalar/DeadStoreElimination.cpp

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp

1//===- DeadStoreElimination.cpp - MemorySSA Backed Dead Store Elimination -===//
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// The code below implements dead store elimination using MemorySSA. It uses
10// the following general approach: given a MemoryDef, walk upwards to find
11// clobbering MemoryDefs that may be killed by the starting def. Then check
12// that there are no uses that may read the location of the original MemoryDef
13// in between both MemoryDefs. A bit more concretely:
14//
15// For all MemoryDefs StartDef:
16// 1. Get the next dominating clobbering MemoryDef (EarlierAccess) by walking
17// upwards.
18// 2. Check that there are no reads between EarlierAccess and the StartDef by
19// checking all uses starting at EarlierAccess and walking until we see
20// StartDef.
21// 3. For each found CurrentDef, check that:
22// 1. There are no barrier instructions between CurrentDef and StartDef (like
23// throws or stores with ordering constraints).
24// 2. StartDef is executed whenever CurrentDef is executed.
25// 3. StartDef completely overwrites CurrentDef.
26// 4. Erase CurrentDef from the function and MemorySSA.
27//
28//===----------------------------------------------------------------------===//
29
30#include "llvm/Transforms/Scalar/DeadStoreElimination.h"
31#include "llvm/ADT/APInt.h"
32#include "llvm/ADT/DenseMap.h"
33#include "llvm/ADT/MapVector.h"
34#include "llvm/ADT/PostOrderIterator.h"
35#include "llvm/ADT/SetVector.h"
36#include "llvm/ADT/SmallPtrSet.h"
37#include "llvm/ADT/SmallVector.h"
38#include "llvm/ADT/Statistic.h"
39#include "llvm/ADT/StringRef.h"
40#include "llvm/Analysis/AliasAnalysis.h"
41#include "llvm/Analysis/CaptureTracking.h"
42#include "llvm/Analysis/GlobalsModRef.h"
43#include "llvm/Analysis/LoopInfo.h"
44#include "llvm/Analysis/MemoryBuiltins.h"
45#include "llvm/Analysis/MemoryLocation.h"
46#include "llvm/Analysis/MemorySSA.h"
47#include "llvm/Analysis/MemorySSAUpdater.h"
48#include "llvm/Analysis/MustExecute.h"
49#include "llvm/Analysis/PostDominators.h"
50#include "llvm/Analysis/TargetLibraryInfo.h"
51#include "llvm/Analysis/ValueTracking.h"
52#include "llvm/IR/Argument.h"
53#include "llvm/IR/BasicBlock.h"
54#include "llvm/IR/Constant.h"
55#include "llvm/IR/Constants.h"
56#include "llvm/IR/DataLayout.h"
57#include "llvm/IR/Dominators.h"
58#include "llvm/IR/Function.h"
59#include "llvm/IR/InstIterator.h"
60#include "llvm/IR/InstrTypes.h"
61#include "llvm/IR/Instruction.h"
62#include "llvm/IR/Instructions.h"
63#include "llvm/IR/IntrinsicInst.h"
64#include "llvm/IR/Intrinsics.h"
65#include "llvm/IR/LLVMContext.h"
66#include "llvm/IR/Module.h"
67#include "llvm/IR/PassManager.h"
68#include "llvm/IR/PatternMatch.h"
69#include "llvm/IR/Value.h"
70#include "llvm/InitializePasses.h"
71#include "llvm/Pass.h"
72#include "llvm/Support/Casting.h"
73#include "llvm/Support/CommandLine.h"
74#include "llvm/Support/Debug.h"
75#include "llvm/Support/DebugCounter.h"
76#include "llvm/Support/ErrorHandling.h"
77#include "llvm/Support/MathExtras.h"
78#include "llvm/Support/raw_ostream.h"
79#include "llvm/Transforms/Scalar.h"
80#include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
81#include "llvm/Transforms/Utils/Local.h"
82#include <algorithm>
83#include <cassert>
84#include <cstddef>
85#include <cstdint>
86#include <iterator>
87#include <map>
88#include <utility>
89
90using namespace llvm;
91using namespace PatternMatch;
92
93#define DEBUG_TYPE"dse" "dse"
94
95STATISTIC(NumRemainingStores, "Number of stores remaining after DSE")static llvm::Statistic NumRemainingStores = {"dse", "NumRemainingStores"
, "Number of stores remaining after DSE"}
;
96STATISTIC(NumRedundantStores, "Number of redundant stores deleted")static llvm::Statistic NumRedundantStores = {"dse", "NumRedundantStores"
, "Number of redundant stores deleted"}
;
97STATISTIC(NumFastStores, "Number of stores deleted")static llvm::Statistic NumFastStores = {"dse", "NumFastStores"
, "Number of stores deleted"}
;
98STATISTIC(NumFastOther, "Number of other instrs removed")static llvm::Statistic NumFastOther = {"dse", "NumFastOther",
"Number of other instrs removed"}
;
99STATISTIC(NumCompletePartials, "Number of stores dead by later partials")static llvm::Statistic NumCompletePartials = {"dse", "NumCompletePartials"
, "Number of stores dead by later partials"}
;
100STATISTIC(NumModifiedStores, "Number of stores modified")static llvm::Statistic NumModifiedStores = {"dse", "NumModifiedStores"
, "Number of stores modified"}
;
101STATISTIC(NumCFGChecks, "Number of stores modified")static llvm::Statistic NumCFGChecks = {"dse", "NumCFGChecks",
"Number of stores modified"}
;
102STATISTIC(NumCFGTries, "Number of stores modified")static llvm::Statistic NumCFGTries = {"dse", "NumCFGTries", "Number of stores modified"
}
;
103STATISTIC(NumCFGSuccess, "Number of stores modified")static llvm::Statistic NumCFGSuccess = {"dse", "NumCFGSuccess"
, "Number of stores modified"}
;
104STATISTIC(NumGetDomMemoryDefPassed,static llvm::Statistic NumGetDomMemoryDefPassed = {"dse", "NumGetDomMemoryDefPassed"
, "Number of times a valid candidate is returned from getDomMemoryDef"
}
105 "Number of times a valid candidate is returned from getDomMemoryDef")static llvm::Statistic NumGetDomMemoryDefPassed = {"dse", "NumGetDomMemoryDefPassed"
, "Number of times a valid candidate is returned from getDomMemoryDef"
}
;
106STATISTIC(NumDomMemDefChecks,static llvm::Statistic NumDomMemDefChecks = {"dse", "NumDomMemDefChecks"
, "Number iterations check for reads in getDomMemoryDef"}
107 "Number iterations check for reads in getDomMemoryDef")static llvm::Statistic NumDomMemDefChecks = {"dse", "NumDomMemDefChecks"
, "Number iterations check for reads in getDomMemoryDef"}
;
108
109DEBUG_COUNTER(MemorySSACounter, "dse-memoryssa",static const unsigned MemorySSACounter = DebugCounter::registerCounter
("dse-memoryssa", "Controls which MemoryDefs are eliminated."
)
110 "Controls which MemoryDefs are eliminated.")static const unsigned MemorySSACounter = DebugCounter::registerCounter
("dse-memoryssa", "Controls which MemoryDefs are eliminated."
)
;
111
112static cl::opt<bool>
113EnablePartialOverwriteTracking("enable-dse-partial-overwrite-tracking",
114 cl::init(true), cl::Hidden,
115 cl::desc("Enable partial-overwrite tracking in DSE"));
116
117static cl::opt<bool>
118EnablePartialStoreMerging("enable-dse-partial-store-merging",
119 cl::init(true), cl::Hidden,
120 cl::desc("Enable partial store merging in DSE"));
121
122static cl::opt<unsigned>
123 MemorySSAScanLimit("dse-memoryssa-scanlimit", cl::init(150), cl::Hidden,
124 cl::desc("The number of memory instructions to scan for "
125 "dead store elimination (default = 100)"));
126static cl::opt<unsigned> MemorySSAUpwardsStepLimit(
127 "dse-memoryssa-walklimit", cl::init(90), cl::Hidden,
128 cl::desc("The maximum number of steps while walking upwards to find "
129 "MemoryDefs that may be killed (default = 90)"));
130
131static cl::opt<unsigned> MemorySSAPartialStoreLimit(
132 "dse-memoryssa-partial-store-limit", cl::init(5), cl::Hidden,
133 cl::desc("The maximum number candidates that only partially overwrite the "
134 "killing MemoryDef to consider"
135 " (default = 5)"));
136
137static cl::opt<unsigned> MemorySSADefsPerBlockLimit(
138 "dse-memoryssa-defs-per-block-limit", cl::init(5000), cl::Hidden,
139 cl::desc("The number of MemoryDefs we consider as candidates to eliminated "
140 "other stores per basic block (default = 5000)"));
141
142static cl::opt<unsigned> MemorySSASameBBStepCost(
143 "dse-memoryssa-samebb-cost", cl::init(1), cl::Hidden,
144 cl::desc(
145 "The cost of a step in the same basic block as the killing MemoryDef"
146 "(default = 1)"));
147
148static cl::opt<unsigned>
149 MemorySSAOtherBBStepCost("dse-memoryssa-otherbb-cost", cl::init(5),
150 cl::Hidden,
151 cl::desc("The cost of a step in a different basic "
152 "block than the killing MemoryDef"
153 "(default = 5)"));
154
155static cl::opt<unsigned> MemorySSAPathCheckLimit(
156 "dse-memoryssa-path-check-limit", cl::init(50), cl::Hidden,
157 cl::desc("The maximum number of blocks to check when trying to prove that "
158 "all paths to an exit go through a killing block (default = 50)"));
159
160//===----------------------------------------------------------------------===//
161// Helper functions
162//===----------------------------------------------------------------------===//
163using OverlapIntervalsTy = std::map<int64_t, int64_t>;
164using InstOverlapIntervalsTy = DenseMap<Instruction *, OverlapIntervalsTy>;
165
166/// Does this instruction write some memory? This only returns true for things
167/// that we can analyze with other helpers below.
168static bool hasAnalyzableMemoryWrite(Instruction *I,
169 const TargetLibraryInfo &TLI) {
170 if (isa<StoreInst>(I))
171 return true;
172 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
173 switch (II->getIntrinsicID()) {
174 default:
175 return false;
176 case Intrinsic::memset:
177 case Intrinsic::memmove:
178 case Intrinsic::memcpy:
179 case Intrinsic::memcpy_inline:
180 case Intrinsic::memcpy_element_unordered_atomic:
181 case Intrinsic::memmove_element_unordered_atomic:
182 case Intrinsic::memset_element_unordered_atomic:
183 case Intrinsic::init_trampoline:
184 case Intrinsic::lifetime_end:
185 case Intrinsic::masked_store:
186 return true;
187 }
188 }
189 if (auto *CB = dyn_cast<CallBase>(I)) {
190 LibFunc LF;
191 if (TLI.getLibFunc(*CB, LF) && TLI.has(LF)) {
192 switch (LF) {
193 case LibFunc_strcpy:
194 case LibFunc_strncpy:
195 case LibFunc_strcat:
196 case LibFunc_strncat:
197 return true;
198 default:
199 return false;
200 }
201 }
202 }
203 return false;
204}
205
206/// Return a Location stored to by the specified instruction. If isRemovable
207/// returns true, this function and getLocForRead completely describe the memory
208/// operations for this instruction.
209static MemoryLocation getLocForWrite(Instruction *Inst,
210 const TargetLibraryInfo &TLI) {
211 if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
212 return MemoryLocation::get(SI);
213
214 // memcpy/memmove/memset.
215 if (auto *MI = dyn_cast<AnyMemIntrinsic>(Inst))
216 return MemoryLocation::getForDest(MI);
217
218 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
219 switch (II->getIntrinsicID()) {
220 default:
221 return MemoryLocation(); // Unhandled intrinsic.
222 case Intrinsic::init_trampoline:
223 return MemoryLocation::getAfter(II->getArgOperand(0));
224 case Intrinsic::masked_store:
225 return MemoryLocation::getForArgument(II, 1, TLI);
226 case Intrinsic::lifetime_end: {
227 uint64_t Len = cast<ConstantInt>(II->getArgOperand(0))->getZExtValue();
228 return MemoryLocation(II->getArgOperand(1), Len);
229 }
230 }
231 }
232 if (auto *CB = dyn_cast<CallBase>(Inst))
233 // All the supported TLI functions so far happen to have dest as their
234 // first argument.
235 return MemoryLocation::getAfter(CB->getArgOperand(0));
236 return MemoryLocation();
237}
238
239/// If the value of this instruction and the memory it writes to is unused, may
240/// we delete this instruction?
241static bool isRemovable(Instruction *I) {
242 // Don't remove volatile/atomic stores.
243 if (StoreInst *SI = dyn_cast<StoreInst>(I))
244 return SI->isUnordered();
245
246 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
247 switch (II->getIntrinsicID()) {
248 default: llvm_unreachable("doesn't pass 'hasAnalyzableMemoryWrite' predicate")__builtin_unreachable();
249 case Intrinsic::lifetime_end:
250 // Never remove dead lifetime_end's, e.g. because it is followed by a
251 // free.
252 return false;
253 case Intrinsic::init_trampoline:
254 // Always safe to remove init_trampoline.
255 return true;
256 case Intrinsic::memset:
257 case Intrinsic::memmove:
258 case Intrinsic::memcpy:
259 case Intrinsic::memcpy_inline:
260 // Don't remove volatile memory intrinsics.
261 return !cast<MemIntrinsic>(II)->isVolatile();
262 case Intrinsic::memcpy_element_unordered_atomic:
263 case Intrinsic::memmove_element_unordered_atomic:
264 case Intrinsic::memset_element_unordered_atomic:
265 case Intrinsic::masked_store:
266 return true;
267 }
268 }
269
270 // note: only get here for calls with analyzable writes - i.e. libcalls
271 if (auto *CB = dyn_cast<CallBase>(I))
272 return CB->use_empty();
273
274 return false;
275}
276
277/// Returns true if the end of this instruction can be safely shortened in
278/// length.
279static bool isShortenableAtTheEnd(Instruction *I) {
280 // Don't shorten stores for now
281 if (isa<StoreInst>(I))
282 return false;
283
284 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
285 switch (II->getIntrinsicID()) {
286 default: return false;
287 case Intrinsic::memset:
288 case Intrinsic::memcpy:
289 case Intrinsic::memcpy_element_unordered_atomic:
290 case Intrinsic::memset_element_unordered_atomic:
291 // Do shorten memory intrinsics.
292 // FIXME: Add memmove if it's also safe to transform.
293 return true;
294 }
295 }
296
297 // Don't shorten libcalls calls for now.
298
299 return false;
300}
301
302/// Returns true if the beginning of this instruction can be safely shortened
303/// in length.
304static bool isShortenableAtTheBeginning(Instruction *I) {
305 // FIXME: Handle only memset for now. Supporting memcpy/memmove should be
306 // easily done by offsetting the source address.
307 return isa<AnyMemSetInst>(I);
308}
309
310static uint64_t getPointerSize(const Value *V, const DataLayout &DL,
311 const TargetLibraryInfo &TLI,
312 const Function *F) {
313 uint64_t Size;
314 ObjectSizeOpts Opts;
315 Opts.NullIsUnknownSize = NullPointerIsDefined(F);
316
317 if (getObjectSize(V, Size, DL, &TLI, Opts))
318 return Size;
319 return MemoryLocation::UnknownSize;
320}
321
322namespace {
323
324enum OverwriteResult {
325 OW_Begin,
326 OW_Complete,
327 OW_End,
328 OW_PartialEarlierWithFullLater,
329 OW_MaybePartial,
330 OW_Unknown
331};
332
333} // end anonymous namespace
334
335/// Check if two instruction are masked stores that completely
336/// overwrite one another. More specifically, \p Later has to
337/// overwrite \p Earlier.
338static OverwriteResult isMaskedStoreOverwrite(const Instruction *Later,
339 const Instruction *Earlier,
340 BatchAAResults &AA) {
341 const auto *IIL = dyn_cast<IntrinsicInst>(Later);
342 const auto *IIE = dyn_cast<IntrinsicInst>(Earlier);
343 if (IIL == nullptr || IIE == nullptr)
344 return OW_Unknown;
345 if (IIL->getIntrinsicID() != Intrinsic::masked_store ||
346 IIE->getIntrinsicID() != Intrinsic::masked_store)
347 return OW_Unknown;
348 // Pointers.
349 Value *LP = IIL->getArgOperand(1)->stripPointerCasts();
350 Value *EP = IIE->getArgOperand(1)->stripPointerCasts();
351 if (LP != EP && !AA.isMustAlias(LP, EP))
352 return OW_Unknown;
353 // Masks.
354 // TODO: check that Later's mask is a superset of the Earlier's mask.
355 if (IIL->getArgOperand(3) != IIE->getArgOperand(3))
356 return OW_Unknown;
357 return OW_Complete;
358}
359
360/// Return 'OW_Complete' if a store to the 'Later' location completely
361/// overwrites a store to the 'Earlier' location, 'OW_End' if the end of the
362/// 'Earlier' location is completely overwritten by 'Later', 'OW_Begin' if the
363/// beginning of the 'Earlier' location is overwritten by 'Later'.
364/// 'OW_PartialEarlierWithFullLater' means that an earlier (big) store was
365/// overwritten by a latter (smaller) store which doesn't write outside the big
366/// store's memory locations. Returns 'OW_Unknown' if nothing can be determined.
367/// NOTE: This function must only be called if both \p Later and \p Earlier
368/// write to the same underlying object with valid \p EarlierOff and \p
369/// LaterOff.
370static OverwriteResult isPartialOverwrite(const MemoryLocation &Later,
371 const MemoryLocation &Earlier,
372 int64_t EarlierOff, int64_t LaterOff,
373 Instruction *DepWrite,
374 InstOverlapIntervalsTy &IOL) {
375 const uint64_t LaterSize = Later.Size.getValue();
376 const uint64_t EarlierSize = Earlier.Size.getValue();
377 // We may now overlap, although the overlap is not complete. There might also
378 // be other incomplete overlaps, and together, they might cover the complete
379 // earlier write.
380 // Note: The correctness of this logic depends on the fact that this function
381 // is not even called providing DepWrite when there are any intervening reads.
382 if (EnablePartialOverwriteTracking &&
383 LaterOff < int64_t(EarlierOff + EarlierSize) &&
384 int64_t(LaterOff + LaterSize) >= EarlierOff) {
385
386 // Insert our part of the overlap into the map.
387 auto &IM = IOL[DepWrite];
388 LLVM_DEBUG(dbgs() << "DSE: Partial overwrite: Earlier [" << EarlierOffdo { } while (false)
389 << ", " << int64_t(EarlierOff + EarlierSize)do { } while (false)
390 << ") Later [" << LaterOff << ", "do { } while (false)
391 << int64_t(LaterOff + LaterSize) << ")\n")do { } while (false);
392
393 // Make sure that we only insert non-overlapping intervals and combine
394 // adjacent intervals. The intervals are stored in the map with the ending
395 // offset as the key (in the half-open sense) and the starting offset as
396 // the value.
397 int64_t LaterIntStart = LaterOff, LaterIntEnd = LaterOff + LaterSize;
398
399 // Find any intervals ending at, or after, LaterIntStart which start
400 // before LaterIntEnd.
401 auto ILI = IM.lower_bound(LaterIntStart);
402 if (ILI != IM.end() && ILI->second <= LaterIntEnd) {
403 // This existing interval is overlapped with the current store somewhere
404 // in [LaterIntStart, LaterIntEnd]. Merge them by erasing the existing
405 // intervals and adjusting our start and end.
406 LaterIntStart = std::min(LaterIntStart, ILI->second);
407 LaterIntEnd = std::max(LaterIntEnd, ILI->first);
408 ILI = IM.erase(ILI);
409
410 // Continue erasing and adjusting our end in case other previous
411 // intervals are also overlapped with the current store.
412 //
413 // |--- ealier 1 ---| |--- ealier 2 ---|
414 // |------- later---------|
415 //
416 while (ILI != IM.end() && ILI->second <= LaterIntEnd) {
417 assert(ILI->second > LaterIntStart && "Unexpected interval")((void)0);
418 LaterIntEnd = std::max(LaterIntEnd, ILI->first);
419 ILI = IM.erase(ILI);
420 }
421 }
422
423 IM[LaterIntEnd] = LaterIntStart;
424
425 ILI = IM.begin();
426 if (ILI->second <= EarlierOff &&
427 ILI->first >= int64_t(EarlierOff + EarlierSize)) {
428 LLVM_DEBUG(dbgs() << "DSE: Full overwrite from partials: Earlier ["do { } while (false)
429 << EarlierOff << ", "do { } while (false)
430 << int64_t(EarlierOff + EarlierSize)do { } while (false)
431 << ") Composite Later [" << ILI->second << ", "do { } while (false)
432 << ILI->first << ")\n")do { } while (false);
433 ++NumCompletePartials;
434 return OW_Complete;
435 }
436 }
437
438 // Check for an earlier store which writes to all the memory locations that
439 // the later store writes to.
440 if (EnablePartialStoreMerging && LaterOff >= EarlierOff &&
441 int64_t(EarlierOff + EarlierSize) > LaterOff &&
442 uint64_t(LaterOff - EarlierOff) + LaterSize <= EarlierSize) {
443 LLVM_DEBUG(dbgs() << "DSE: Partial overwrite an earlier load ["do { } while (false)
444 << EarlierOff << ", "do { } while (false)
445 << int64_t(EarlierOff + EarlierSize)do { } while (false)
446 << ") by a later store [" << LaterOff << ", "do { } while (false)
447 << int64_t(LaterOff + LaterSize) << ")\n")do { } while (false);
448 // TODO: Maybe come up with a better name?
449 return OW_PartialEarlierWithFullLater;
450 }
451
452 // Another interesting case is if the later store overwrites the end of the
453 // earlier store.
454 //
455 // |--earlier--|
456 // |-- later --|
457 //
458 // In this case we may want to trim the size of earlier to avoid generating
459 // writes to addresses which will definitely be overwritten later
460 if (!EnablePartialOverwriteTracking &&
461 (LaterOff > EarlierOff && LaterOff < int64_t(EarlierOff + EarlierSize) &&
462 int64_t(LaterOff + LaterSize) >= int64_t(EarlierOff + EarlierSize)))
463 return OW_End;
464
465 // Finally, we also need to check if the later store overwrites the beginning
466 // of the earlier store.
467 //
468 // |--earlier--|
469 // |-- later --|
470 //
471 // In this case we may want to move the destination address and trim the size
472 // of earlier to avoid generating writes to addresses which will definitely
473 // be overwritten later.
474 if (!EnablePartialOverwriteTracking &&
475 (LaterOff <= EarlierOff && int64_t(LaterOff + LaterSize) > EarlierOff)) {
476 assert(int64_t(LaterOff + LaterSize) < int64_t(EarlierOff + EarlierSize) &&((void)0)
477 "Expect to be handled as OW_Complete")((void)0);
478 return OW_Begin;
479 }
480 // Otherwise, they don't completely overlap.
481 return OW_Unknown;
482}
483
484/// Returns true if the memory which is accessed by the second instruction is not
485/// modified between the first and the second instruction.
486/// Precondition: Second instruction must be dominated by the first
487/// instruction.
488static bool
489memoryIsNotModifiedBetween(Instruction *FirstI, Instruction *SecondI,
490 BatchAAResults &AA, const DataLayout &DL,
491 DominatorTree *DT) {
492 // Do a backwards scan through the CFG from SecondI to FirstI. Look for
493 // instructions which can modify the memory location accessed by SecondI.
494 //
495 // While doing the walk keep track of the address to check. It might be
496 // different in different basic blocks due to PHI translation.
497 using BlockAddressPair = std::pair<BasicBlock *, PHITransAddr>;
498 SmallVector<BlockAddressPair, 16> WorkList;
499 // Keep track of the address we visited each block with. Bail out if we
500 // visit a block with different addresses.
501 DenseMap<BasicBlock *, Value *> Visited;
502
503 BasicBlock::iterator FirstBBI(FirstI);
504 ++FirstBBI;
505 BasicBlock::iterator SecondBBI(SecondI);
506 BasicBlock *FirstBB = FirstI->getParent();
507 BasicBlock *SecondBB = SecondI->getParent();
508 MemoryLocation MemLoc = MemoryLocation::get(SecondI);
509 auto *MemLocPtr = const_cast<Value *>(MemLoc.Ptr);
510
511 // Start checking the SecondBB.
512 WorkList.push_back(
513 std::make_pair(SecondBB, PHITransAddr(MemLocPtr, DL, nullptr)));
514 bool isFirstBlock = true;
515
516 // Check all blocks going backward until we reach the FirstBB.
517 while (!WorkList.empty()) {
518 BlockAddressPair Current = WorkList.pop_back_val();
519 BasicBlock *B = Current.first;
520 PHITransAddr &Addr = Current.second;
521 Value *Ptr = Addr.getAddr();
522
523 // Ignore instructions before FirstI if this is the FirstBB.
524 BasicBlock::iterator BI = (B == FirstBB ? FirstBBI : B->begin());
525
526 BasicBlock::iterator EI;
527 if (isFirstBlock) {
528 // Ignore instructions after SecondI if this is the first visit of SecondBB.
529 assert(B == SecondBB && "first block is not the store block")((void)0);
530 EI = SecondBBI;
531 isFirstBlock = false;
532 } else {
533 // It's not SecondBB or (in case of a loop) the second visit of SecondBB.
534 // In this case we also have to look at instructions after SecondI.
535 EI = B->end();
536 }
537 for (; BI != EI; ++BI) {
538 Instruction *I = &*BI;
539 if (I->mayWriteToMemory() && I != SecondI)
540 if (isModSet(AA.getModRefInfo(I, MemLoc.getWithNewPtr(Ptr))))
541 return false;
542 }
543 if (B != FirstBB) {
544 assert(B != &FirstBB->getParent()->getEntryBlock() &&((void)0)
545 "Should not hit the entry block because SI must be dominated by LI")((void)0);
546 for (BasicBlock *Pred : predecessors(B)) {
547 PHITransAddr PredAddr = Addr;
548 if (PredAddr.NeedsPHITranslationFromBlock(B)) {
549 if (!PredAddr.IsPotentiallyPHITranslatable())
550 return false;
551 if (PredAddr.PHITranslateValue(B, Pred, DT, false))
552 return false;
553 }
554 Value *TranslatedPtr = PredAddr.getAddr();
555 auto Inserted = Visited.insert(std::make_pair(Pred, TranslatedPtr));
556 if (!Inserted.second) {
557 // We already visited this block before. If it was with a different
558 // address - bail out!
559 if (TranslatedPtr != Inserted.first->second)
560 return false;
561 // ... otherwise just skip it.
562 continue;
563 }
564 WorkList.push_back(std::make_pair(Pred, PredAddr));
565 }
566 }
567 }
568 return true;
569}
570
571static bool tryToShorten(Instruction *EarlierWrite, int64_t &EarlierStart,
572 uint64_t &EarlierSize, int64_t LaterStart,
573 uint64_t LaterSize, bool IsOverwriteEnd) {
574 auto *EarlierIntrinsic = cast<AnyMemIntrinsic>(EarlierWrite);
575 Align PrefAlign = EarlierIntrinsic->getDestAlign().valueOrOne();
576
577 // We assume that memet/memcpy operates in chunks of the "largest" native
578 // type size and aligned on the same value. That means optimal start and size
579 // of memset/memcpy should be modulo of preferred alignment of that type. That
580 // is it there is no any sense in trying to reduce store size any further
581 // since any "extra" stores comes for free anyway.
582 // On the other hand, maximum alignment we can achieve is limited by alignment
583 // of initial store.
584
585 // TODO: Limit maximum alignment by preferred (or abi?) alignment of the
586 // "largest" native type.
587 // Note: What is the proper way to get that value?
588 // Should TargetTransformInfo::getRegisterBitWidth be used or anything else?
589 // PrefAlign = std::min(DL.getPrefTypeAlign(LargestType), PrefAlign);
590
591 int64_t ToRemoveStart = 0;
592 uint64_t ToRemoveSize = 0;
593 // Compute start and size of the region to remove. Make sure 'PrefAlign' is
594 // maintained on the remaining store.
595 if (IsOverwriteEnd) {
596 // Calculate required adjustment for 'LaterStart'in order to keep remaining
597 // store size aligned on 'PerfAlign'.
598 uint64_t Off =
599 offsetToAlignment(uint64_t(LaterStart - EarlierStart), PrefAlign);
600 ToRemoveStart = LaterStart + Off;
601 if (EarlierSize <= uint64_t(ToRemoveStart - EarlierStart))
602 return false;
603 ToRemoveSize = EarlierSize - uint64_t(ToRemoveStart - EarlierStart);
604 } else {
605 ToRemoveStart = EarlierStart;
606 assert(LaterSize >= uint64_t(EarlierStart - LaterStart) &&((void)0)
607 "Not overlapping accesses?")((void)0);
608 ToRemoveSize = LaterSize - uint64_t(EarlierStart - LaterStart);
609 // Calculate required adjustment for 'ToRemoveSize'in order to keep
610 // start of the remaining store aligned on 'PerfAlign'.
611 uint64_t Off = offsetToAlignment(ToRemoveSize, PrefAlign);
612 if (Off != 0) {
613 if (ToRemoveSize <= (PrefAlign.value() - Off))
614 return false;
615 ToRemoveSize -= PrefAlign.value() - Off;
616 }
617 assert(isAligned(PrefAlign, ToRemoveSize) &&((void)0)
618 "Should preserve selected alignment")((void)0);
619 }
620
621 assert(ToRemoveSize > 0 && "Shouldn't reach here if nothing to remove")((void)0);
622 assert(EarlierSize > ToRemoveSize && "Can't remove more than original size")((void)0);
623
624 uint64_t NewSize = EarlierSize - ToRemoveSize;
625 if (auto *AMI = dyn_cast<AtomicMemIntrinsic>(EarlierWrite)) {
626 // When shortening an atomic memory intrinsic, the newly shortened
627 // length must remain an integer multiple of the element size.
628 const uint32_t ElementSize = AMI->getElementSizeInBytes();
629 if (0 != NewSize % ElementSize)
630 return false;
631 }
632
633 LLVM_DEBUG(dbgs() << "DSE: Remove Dead Store:\n OW "do { } while (false)
634 << (IsOverwriteEnd ? "END" : "BEGIN") << ": "do { } while (false)
635 << *EarlierWrite << "\n KILLER [" << ToRemoveStart << ", "do { } while (false)
636 << int64_t(ToRemoveStart + ToRemoveSize) << ")\n")do { } while (false);
637
638 Value *EarlierWriteLength = EarlierIntrinsic->getLength();
639 Value *TrimmedLength =
640 ConstantInt::get(EarlierWriteLength->getType(), NewSize);
641 EarlierIntrinsic->setLength(TrimmedLength);
642 EarlierIntrinsic->setDestAlignment(PrefAlign);
643
644 if (!IsOverwriteEnd) {
645 Value *OrigDest = EarlierIntrinsic->getRawDest();
646 Type *Int8PtrTy =
647 Type::getInt8PtrTy(EarlierIntrinsic->getContext(),
648 OrigDest->getType()->getPointerAddressSpace());
649 Value *Dest = OrigDest;
650 if (OrigDest->getType() != Int8PtrTy)
651 Dest = CastInst::CreatePointerCast(OrigDest, Int8PtrTy, "", EarlierWrite);
652 Value *Indices[1] = {
653 ConstantInt::get(EarlierWriteLength->getType(), ToRemoveSize)};
654 Instruction *NewDestGEP = GetElementPtrInst::CreateInBounds(
655 Type::getInt8Ty(EarlierIntrinsic->getContext()),
656 Dest, Indices, "", EarlierWrite);
657 NewDestGEP->setDebugLoc(EarlierIntrinsic->getDebugLoc());
658 if (NewDestGEP->getType() != OrigDest->getType())
659 NewDestGEP = CastInst::CreatePointerCast(NewDestGEP, OrigDest->getType(),
660 "", EarlierWrite);
661 EarlierIntrinsic->setDest(NewDestGEP);
662 }
663
664 // Finally update start and size of earlier access.
665 if (!IsOverwriteEnd)
666 EarlierStart += ToRemoveSize;
667 EarlierSize = NewSize;
668
669 return true;
670}
671
672static bool tryToShortenEnd(Instruction *EarlierWrite,
673 OverlapIntervalsTy &IntervalMap,
674 int64_t &EarlierStart, uint64_t &EarlierSize) {
675 if (IntervalMap.empty() || !isShortenableAtTheEnd(EarlierWrite))
676 return false;
677
678 OverlapIntervalsTy::iterator OII = --IntervalMap.end();
679 int64_t LaterStart = OII->second;
680 uint64_t LaterSize = OII->first - LaterStart;
681
682 assert(OII->first - LaterStart >= 0 && "Size expected to be positive")((void)0);
683
684 if (LaterStart > EarlierStart &&
685 // Note: "LaterStart - EarlierStart" is known to be positive due to
686 // preceding check.
687 (uint64_t)(LaterStart - EarlierStart) < EarlierSize &&
688 // Note: "EarlierSize - (uint64_t)(LaterStart - EarlierStart)" is known to
689 // be non negative due to preceding checks.
690 LaterSize >= EarlierSize - (uint64_t)(LaterStart - EarlierStart)) {
691 if (tryToShorten(EarlierWrite, EarlierStart, EarlierSize, LaterStart,
692 LaterSize, true)) {
693 IntervalMap.erase(OII);
694 return true;
695 }
696 }
697 return false;
698}
699
700static bool tryToShortenBegin(Instruction *EarlierWrite,
701 OverlapIntervalsTy &IntervalMap,
702 int64_t &EarlierStart, uint64_t &EarlierSize) {
703 if (IntervalMap.empty() || !isShortenableAtTheBeginning(EarlierWrite))
704 return false;
705
706 OverlapIntervalsTy::iterator OII = IntervalMap.begin();
707 int64_t LaterStart = OII->second;
708 uint64_t LaterSize = OII->first - LaterStart;
709
710 assert(OII->first - LaterStart >= 0 && "Size expected to be positive")((void)0);
711
712 if (LaterStart <= EarlierStart &&
713 // Note: "EarlierStart - LaterStart" is known to be non negative due to
714 // preceding check.
715 LaterSize > (uint64_t)(EarlierStart - LaterStart)) {
716 // Note: "LaterSize - (uint64_t)(EarlierStart - LaterStart)" is known to be
717 // positive due to preceding checks.
718 assert(LaterSize - (uint64_t)(EarlierStart - LaterStart) < EarlierSize &&((void)0)
719 "Should have been handled as OW_Complete")((void)0);
720 if (tryToShorten(EarlierWrite, EarlierStart, EarlierSize, LaterStart,
721 LaterSize, false)) {
722 IntervalMap.erase(OII);
723 return true;
724 }
725 }
726 return false;
727}
728
729static bool removePartiallyOverlappedStores(const DataLayout &DL,
730 InstOverlapIntervalsTy &IOL,
731 const TargetLibraryInfo &TLI) {
732 bool Changed = false;
733 for (auto OI : IOL) {
734 Instruction *EarlierWrite = OI.first;
735 MemoryLocation Loc = getLocForWrite(EarlierWrite, TLI);
736 assert(isRemovable(EarlierWrite) && "Expect only removable instruction")((void)0);
737
738 const Value *Ptr = Loc.Ptr->stripPointerCasts();
739 int64_t EarlierStart = 0;
740 uint64_t EarlierSize = Loc.Size.getValue();
741 GetPointerBaseWithConstantOffset(Ptr, EarlierStart, DL);
742 OverlapIntervalsTy &IntervalMap = OI.second;
743 Changed |=
744 tryToShortenEnd(EarlierWrite, IntervalMap, EarlierStart, EarlierSize);
745 if (IntervalMap.empty())
746 continue;
747 Changed |=
748 tryToShortenBegin(EarlierWrite, IntervalMap, EarlierStart, EarlierSize);
749 }
750 return Changed;
751}
752
753static Constant *tryToMergePartialOverlappingStores(
754 StoreInst *Earlier, StoreInst *Later, int64_t InstWriteOffset,
755 int64_t DepWriteOffset, const DataLayout &DL, BatchAAResults &AA,
756 DominatorTree *DT) {
757
758 if (Earlier && isa<ConstantInt>(Earlier->getValueOperand()) &&
759 DL.typeSizeEqualsStoreSize(Earlier->getValueOperand()->getType()) &&
760 Later && isa<ConstantInt>(Later->getValueOperand()) &&
761 DL.typeSizeEqualsStoreSize(Later->getValueOperand()->getType()) &&
762 memoryIsNotModifiedBetween(Earlier, Later, AA, DL, DT)) {
763 // If the store we find is:
764 // a) partially overwritten by the store to 'Loc'
765 // b) the later store is fully contained in the earlier one and
766 // c) they both have a constant value
767 // d) none of the two stores need padding
768 // Merge the two stores, replacing the earlier store's value with a
769 // merge of both values.
770 // TODO: Deal with other constant types (vectors, etc), and probably
771 // some mem intrinsics (if needed)
772
773 APInt EarlierValue =
774 cast<ConstantInt>(Earlier->getValueOperand())->getValue();
775 APInt LaterValue = cast<ConstantInt>(Later->getValueOperand())->getValue();
776 unsigned LaterBits = LaterValue.getBitWidth();
777 assert(EarlierValue.getBitWidth() > LaterValue.getBitWidth())((void)0);
778 LaterValue = LaterValue.zext(EarlierValue.getBitWidth());
779
780 // Offset of the smaller store inside the larger store
781 unsigned BitOffsetDiff = (InstWriteOffset - DepWriteOffset) * 8;
782 unsigned LShiftAmount = DL.isBigEndian() ? EarlierValue.getBitWidth() -
783 BitOffsetDiff - LaterBits
784 : BitOffsetDiff;
785 APInt Mask = APInt::getBitsSet(EarlierValue.getBitWidth(), LShiftAmount,
786 LShiftAmount + LaterBits);
787 // Clear the bits we'll be replacing, then OR with the smaller
788 // store, shifted appropriately.
789 APInt Merged = (EarlierValue & ~Mask) | (LaterValue << LShiftAmount);
790 LLVM_DEBUG(dbgs() << "DSE: Merge Stores:\n Earlier: " << *Earlierdo { } while (false)
791 << "\n Later: " << *Laterdo { } while (false)
792 << "\n Merged Value: " << Merged << '\n')do { } while (false);
793 return ConstantInt::get(Earlier->getValueOperand()->getType(), Merged);
794 }
795 return nullptr;
796}
797
798namespace {
799// Returns true if \p I is an intrisnic that does not read or write memory.
800bool isNoopIntrinsic(Instruction *I) {
801 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
802 switch (II->getIntrinsicID()) {
803 case Intrinsic::lifetime_start:
804 case Intrinsic::lifetime_end:
805 case Intrinsic::invariant_end:
806 case Intrinsic::launder_invariant_group:
807 case Intrinsic::assume:
808 return true;
809 case Intrinsic::dbg_addr:
810 case Intrinsic::dbg_declare:
811 case Intrinsic::dbg_label:
812 case Intrinsic::dbg_value:
813 llvm_unreachable("Intrinsic should not be modeled in MemorySSA")__builtin_unreachable();
814 default:
815 return false;
816 }
817 }
818 return false;
819}
820
821// Check if we can ignore \p D for DSE.
822bool canSkipDef(MemoryDef *D, bool DefVisibleToCaller) {
823 Instruction *DI = D->getMemoryInst();
824 // Calls that only access inaccessible memory cannot read or write any memory
825 // locations we consider for elimination.
826 if (auto *CB = dyn_cast<CallBase>(DI))
827 if (CB->onlyAccessesInaccessibleMemory())
828 return true;
829
830 // We can eliminate stores to locations not visible to the caller across
831 // throwing instructions.
832 if (DI->mayThrow() && !DefVisibleToCaller)
833 return true;
834
835 // We can remove the dead stores, irrespective of the fence and its ordering
836 // (release/acquire/seq_cst). Fences only constraints the ordering of
837 // already visible stores, it does not make a store visible to other
838 // threads. So, skipping over a fence does not change a store from being
839 // dead.
840 if (isa<FenceInst>(DI))
841 return true;
842
843 // Skip intrinsics that do not really read or modify memory.
844 if (isNoopIntrinsic(D->getMemoryInst()))
845 return true;
846
847 return false;
848}
849
850struct DSEState {
851 Function &F;
852 AliasAnalysis &AA;
853
854 /// The single BatchAA instance that is used to cache AA queries. It will
855 /// not be invalidated over the whole run. This is safe, because:
856 /// 1. Only memory writes are removed, so the alias cache for memory
857 /// locations remains valid.
858 /// 2. No new instructions are added (only instructions removed), so cached
859 /// information for a deleted value cannot be accessed by a re-used new
860 /// value pointer.
861 BatchAAResults BatchAA;
862
863 MemorySSA &MSSA;
864 DominatorTree &DT;
865 PostDominatorTree &PDT;
866 const TargetLibraryInfo &TLI;
867 const DataLayout &DL;
868 const LoopInfo &LI;
869
870 // Whether the function contains any irreducible control flow, useful for
871 // being accurately able to detect loops.
872 bool ContainsIrreducibleLoops;
873
874 // All MemoryDefs that potentially could kill other MemDefs.
875 SmallVector<MemoryDef *, 64> MemDefs;
876 // Any that should be skipped as they are already deleted
877 SmallPtrSet<MemoryAccess *, 4> SkipStores;
878 // Keep track of all of the objects that are invisible to the caller before
879 // the function returns.
880 // SmallPtrSet<const Value *, 16> InvisibleToCallerBeforeRet;
881 DenseMap<const Value *, bool> InvisibleToCallerBeforeRet;
882 // Keep track of all of the objects that are invisible to the caller after
883 // the function returns.
884 DenseMap<const Value *, bool> InvisibleToCallerAfterRet;
885 // Keep track of blocks with throwing instructions not modeled in MemorySSA.
886 SmallPtrSet<BasicBlock *, 16> ThrowingBlocks;
887 // Post-order numbers for each basic block. Used to figure out if memory
888 // accesses are executed before another access.
889 DenseMap<BasicBlock *, unsigned> PostOrderNumbers;
890
891 /// Keep track of instructions (partly) overlapping with killing MemoryDefs per
892 /// basic block.
893 DenseMap<BasicBlock *, InstOverlapIntervalsTy> IOLs;
894
895 DSEState(Function &F, AliasAnalysis &AA, MemorySSA &MSSA, DominatorTree &DT,
896 PostDominatorTree &PDT, const TargetLibraryInfo &TLI,
897 const LoopInfo &LI)
898 : F(F), AA(AA), BatchAA(AA), MSSA(MSSA), DT(DT), PDT(PDT), TLI(TLI),
899 DL(F.getParent()->getDataLayout()), LI(LI) {}
900
901 static DSEState get(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
902 DominatorTree &DT, PostDominatorTree &PDT,
903 const TargetLibraryInfo &TLI, const LoopInfo &LI) {
904 DSEState State(F, AA, MSSA, DT, PDT, TLI, LI);
905 // Collect blocks with throwing instructions not modeled in MemorySSA and
906 // alloc-like objects.
907 unsigned PO = 0;
908 for (BasicBlock *BB : post_order(&F)) {
909 State.PostOrderNumbers[BB] = PO++;
910 for (Instruction &I : *BB) {
911 MemoryAccess *MA = MSSA.getMemoryAccess(&I);
912 if (I.mayThrow() && !MA)
913 State.ThrowingBlocks.insert(I.getParent());
914
915 auto *MD = dyn_cast_or_null<MemoryDef>(MA);
916 if (MD && State.MemDefs.size() < MemorySSADefsPerBlockLimit &&
917 (State.getLocForWriteEx(&I) || State.isMemTerminatorInst(&I)))
918 State.MemDefs.push_back(MD);
919 }
920 }
921
922 // Treat byval or inalloca arguments the same as Allocas, stores to them are
923 // dead at the end of the function.
924 for (Argument &AI : F.args())
925 if (AI.hasPassPointeeByValueCopyAttr()) {
926 // For byval, the caller doesn't know the address of the allocation.
927 if (AI.hasByValAttr())
928 State.InvisibleToCallerBeforeRet.insert({&AI, true});
929 State.InvisibleToCallerAfterRet.insert({&AI, true});
930 }
931
932 // Collect whether there is any irreducible control flow in the function.
933 State.ContainsIrreducibleLoops = mayContainIrreducibleControl(F, &LI);
934
935 return State;
936 }
937
938 /// Return 'OW_Complete' if a store to the 'Later' location (by \p LaterI
939 /// instruction) completely overwrites a store to the 'Earlier' location.
940 /// (by \p EarlierI instruction).
941 /// Return OW_MaybePartial if \p Later does not completely overwrite
942 /// \p Earlier, but they both write to the same underlying object. In that
943 /// case, use isPartialOverwrite to check if \p Later partially overwrites
944 /// \p Earlier. Returns 'OW_Unknown' if nothing can be determined.
945 OverwriteResult
946 isOverwrite(const Instruction *LaterI, const Instruction *EarlierI,
947 const MemoryLocation &Later, const MemoryLocation &Earlier,
948 int64_t &EarlierOff, int64_t &LaterOff) {
949 // AliasAnalysis does not always account for loops. Limit overwrite checks
950 // to dependencies for which we can guarantee they are independant of any
951 // loops they are in.
952 if (!isGuaranteedLoopIndependent(EarlierI, LaterI, Earlier))
953 return OW_Unknown;
954
955 // FIXME: Vet that this works for size upper-bounds. Seems unlikely that we'll
956 // get imprecise values here, though (except for unknown sizes).
957 if (!Later.Size.isPrecise() || !Earlier.Size.isPrecise()) {
958 // In case no constant size is known, try to an IR values for the number
959 // of bytes written and check if they match.
960 const auto *LaterMemI = dyn_cast<MemIntrinsic>(LaterI);
961 const auto *EarlierMemI = dyn_cast<MemIntrinsic>(EarlierI);
962 if (LaterMemI && EarlierMemI) {
963 const Value *LaterV = LaterMemI->getLength();
964 const Value *EarlierV = EarlierMemI->getLength();
965 if (LaterV == EarlierV && BatchAA.isMustAlias(Earlier, Later))
966 return OW_Complete;
967 }
968
969 // Masked stores have imprecise locations, but we can reason about them
970 // to some extent.
971 return isMaskedStoreOverwrite(LaterI, EarlierI, BatchAA);
972 }
973
974 const uint64_t LaterSize = Later.Size.getValue();
975 const uint64_t EarlierSize = Earlier.Size.getValue();
976
977 // Query the alias information
978 AliasResult AAR = BatchAA.alias(Later, Earlier);
979
980 // If the start pointers are the same, we just have to compare sizes to see if
981 // the later store was larger than the earlier store.
982 if (AAR == AliasResult::MustAlias) {
983 // Make sure that the Later size is >= the Earlier size.
984 if (LaterSize >= EarlierSize)
985 return OW_Complete;
986 }
987
988 // If we hit a partial alias we may have a full overwrite
989 if (AAR == AliasResult::PartialAlias && AAR.hasOffset()) {
990 int32_t Off = AAR.getOffset();
991 if (Off >= 0 && (uint64_t)Off + EarlierSize <= LaterSize)
992 return OW_Complete;
993 }
994
995 // Check to see if the later store is to the entire object (either a global,
996 // an alloca, or a byval/inalloca argument). If so, then it clearly
997 // overwrites any other store to the same object.
998 const Value *P1 = Earlier.Ptr->stripPointerCasts();
999 const Value *P2 = Later.Ptr->stripPointerCasts();
1000 const Value *UO1 = getUnderlyingObject(P1), *UO2 = getUnderlyingObject(P2);
1001
1002 // If we can't resolve the same pointers to the same object, then we can't
1003 // analyze them at all.
1004 if (UO1 != UO2)
1005 return OW_Unknown;
1006
1007 // If the "Later" store is to a recognizable object, get its size.
1008 uint64_t ObjectSize = getPointerSize(UO2, DL, TLI, &F);
1009 if (ObjectSize != MemoryLocation::UnknownSize)
1010 if (ObjectSize == LaterSize && ObjectSize >= EarlierSize)
1011 return OW_Complete;
1012
1013 // Okay, we have stores to two completely different pointers. Try to
1014 // decompose the pointer into a "base + constant_offset" form. If the base
1015 // pointers are equal, then we can reason about the two stores.
1016 EarlierOff = 0;
1017 LaterOff = 0;
1018 const Value *BP1 = GetPointerBaseWithConstantOffset(P1, EarlierOff, DL);
1019 const Value *BP2 = GetPointerBaseWithConstantOffset(P2, LaterOff, DL);
1020
1021 // If the base pointers still differ, we have two completely different stores.
1022 if (BP1 != BP2)
1023 return OW_Unknown;
1024
1025 // The later access completely overlaps the earlier store if and only if
1026 // both start and end of the earlier one is "inside" the later one:
1027 // |<->|--earlier--|<->|
1028 // |-------later-------|
1029 // Accesses may overlap if and only if start of one of them is "inside"
1030 // another one:
1031 // |<->|--earlier--|<----->|
1032 // |-------later-------|
1033 // OR
1034 // |----- earlier -----|
1035 // |<->|---later---|<----->|
1036 //
1037 // We have to be careful here as *Off is signed while *.Size is unsigned.
1038
1039 // Check if the earlier access starts "not before" the later one.
1040 if (EarlierOff >= LaterOff) {
1041 // If the earlier access ends "not after" the later access then the earlier
1042 // one is completely overwritten by the later one.
1043 if (uint64_t(EarlierOff - LaterOff) + EarlierSize <= LaterSize)
1044 return OW_Complete;
1045 // If start of the earlier access is "before" end of the later access then
1046 // accesses overlap.
1047 else if ((uint64_t)(EarlierOff - LaterOff) < LaterSize)
1048 return OW_MaybePartial;
1049 }
1050 // If start of the later access is "before" end of the earlier access then
1051 // accesses overlap.
1052 else if ((uint64_t)(LaterOff - EarlierOff) < EarlierSize) {
1053 return OW_MaybePartial;
1054 }
1055
1056 // Can reach here only if accesses are known not to overlap. There is no
1057 // dedicated code to indicate no overlap so signal "unknown".
1058 return OW_Unknown;
1059 }
1060
1061 bool isInvisibleToCallerAfterRet(const Value *V) {
1062 if (isa<AllocaInst>(V))
1063 return true;
1064 auto I = InvisibleToCallerAfterRet.insert({V, false});
1065 if (I.second) {
1066 if (!isInvisibleToCallerBeforeRet(V)) {
1067 I.first->second = false;
1068 } else {
1069 auto *Inst = dyn_cast<Instruction>(V);
1070 if (Inst && isAllocLikeFn(Inst, &TLI))
1071 I.first->second = !PointerMayBeCaptured(V, true, false);
1072 }
1073 }
1074 return I.first->second;
1075 }
1076
1077 bool isInvisibleToCallerBeforeRet(const Value *V) {
1078 if (isa<AllocaInst>(V))
1079 return true;
1080 auto I = InvisibleToCallerBeforeRet.insert({V, false});
1081 if (I.second) {
1082 auto *Inst = dyn_cast<Instruction>(V);
1083 if (Inst && isAllocLikeFn(Inst, &TLI))
1084 // NOTE: This could be made more precise by PointerMayBeCapturedBefore
1085 // with the killing MemoryDef. But we refrain from doing so for now to
1086 // limit compile-time and this does not cause any changes to the number
1087 // of stores removed on a large test set in practice.
1088 I.first->second = !PointerMayBeCaptured(V, false, true);
1089 }
1090 return I.first->second;
1091 }
1092
1093 Optional<MemoryLocation> getLocForWriteEx(Instruction *I) const {
1094 if (!I->mayWriteToMemory())
1095 return None;
1096
1097 if (auto *MTI = dyn_cast<AnyMemIntrinsic>(I))
1098 return {MemoryLocation::getForDest(MTI)};
1099
1100 if (auto *CB = dyn_cast<CallBase>(I)) {
1101 // If the functions may write to memory we do not know about, bail out.
1102 if (!CB->onlyAccessesArgMemory() &&
1103 !CB->onlyAccessesInaccessibleMemOrArgMem())
1104 return None;
1105
1106 LibFunc LF;
1107 if (TLI.getLibFunc(*CB, LF) && TLI.has(LF)) {
1108 switch (LF) {
1109 case LibFunc_strcpy:
1110 case LibFunc_strncpy:
1111 case LibFunc_strcat:
1112 case LibFunc_strncat:
1113 return {MemoryLocation::getAfter(CB->getArgOperand(0))};
1114 default:
1115 break;
1116 }
1117 }
1118 switch (CB->getIntrinsicID()) {
1119 case Intrinsic::init_trampoline:
1120 return {MemoryLocation::getAfter(CB->getArgOperand(0))};
1121 case Intrinsic::masked_store:
1122 return {MemoryLocation::getForArgument(CB, 1, TLI)};
1123 default:
1124 break;
1125 }
1126 return None;
1127 }
1128
1129 return MemoryLocation::getOrNone(I);
1130 }
1131
1132 /// Returns true if \p UseInst completely overwrites \p DefLoc
1133 /// (stored by \p DefInst).
1134 bool isCompleteOverwrite(const MemoryLocation &DefLoc, Instruction *DefInst,
1135 Instruction *UseInst) {
1136 // UseInst has a MemoryDef associated in MemorySSA. It's possible for a
1137 // MemoryDef to not write to memory, e.g. a volatile load is modeled as a
1138 // MemoryDef.
1139 if (!UseInst->mayWriteToMemory())
1140 return false;
1141
1142 if (auto *CB = dyn_cast<CallBase>(UseInst))
1143 if (CB->onlyAccessesInaccessibleMemory())
1144 return false;
1145
1146 int64_t InstWriteOffset, DepWriteOffset;
1147 if (auto CC = getLocForWriteEx(UseInst))
1148 return isOverwrite(UseInst, DefInst, *CC, DefLoc, DepWriteOffset,
1149 InstWriteOffset) == OW_Complete;
1150 return false;
1151 }
1152
1153 /// Returns true if \p Def is not read before returning from the function.
1154 bool isWriteAtEndOfFunction(MemoryDef *Def) {
1155 LLVM_DEBUG(dbgs() << " Check if def " << *Def << " ("do { } while (false)
1156 << *Def->getMemoryInst()do { } while (false)
1157 << ") is at the end the function \n")do { } while (false);
1158
1159 auto MaybeLoc = getLocForWriteEx(Def->getMemoryInst());
1160 if (!MaybeLoc) {
1161 LLVM_DEBUG(dbgs() << " ... could not get location for write.\n")do { } while (false);
1162 return false;
1163 }
1164
1165 SmallVector<MemoryAccess *, 4> WorkList;
1166 SmallPtrSet<MemoryAccess *, 8> Visited;
1167 auto PushMemUses = [&WorkList, &Visited](MemoryAccess *Acc) {
1168 if (!Visited.insert(Acc).second)
1169 return;
1170 for (Use &U : Acc->uses())
1171 WorkList.push_back(cast<MemoryAccess>(U.getUser()));
1172 };
1173 PushMemUses(Def);
1174 for (unsigned I = 0; I < WorkList.size(); I++) {
1175 if (WorkList.size() >= MemorySSAScanLimit) {
1176 LLVM_DEBUG(dbgs() << " ... hit exploration limit.\n")do { } while (false);
1177 return false;
1178 }
1179
1180 MemoryAccess *UseAccess = WorkList[I];
1181 // Simply adding the users of MemoryPhi to the worklist is not enough,
1182 // because we might miss read clobbers in different iterations of a loop,
1183 // for example.
1184 // TODO: Add support for phi translation to handle the loop case.
1185 if (isa<MemoryPhi>(UseAccess))
1186 return false;
1187
1188 // TODO: Checking for aliasing is expensive. Consider reducing the amount
1189 // of times this is called and/or caching it.
1190 Instruction *UseInst = cast<MemoryUseOrDef>(UseAccess)->getMemoryInst();
1191 if (isReadClobber(*MaybeLoc, UseInst)) {
1192 LLVM_DEBUG(dbgs() << " ... hit read clobber " << *UseInst << ".\n")do { } while (false);
1193 return false;
1194 }
1195
1196 if (MemoryDef *UseDef = dyn_cast<MemoryDef>(UseAccess))
1197 PushMemUses(UseDef);
1198 }
1199 return true;
1200 }
1201
1202 /// If \p I is a memory terminator like llvm.lifetime.end or free, return a
1203 /// pair with the MemoryLocation terminated by \p I and a boolean flag
1204 /// indicating whether \p I is a free-like call.
1205 Optional<std::pair<MemoryLocation, bool>>
1206 getLocForTerminator(Instruction *I) const {
1207 uint64_t Len;
1208 Value *Ptr;
1209 if (match(I, m_Intrinsic<Intrinsic::lifetime_end>(m_ConstantInt(Len),
1210 m_Value(Ptr))))
1211 return {std::make_pair(MemoryLocation(Ptr, Len), false)};
1212
1213 if (auto *CB = dyn_cast<CallBase>(I)) {
1214 if (isFreeCall(I, &TLI))
1215 return {std::make_pair(MemoryLocation::getAfter(CB->getArgOperand(0)),
1216 true)};
1217 }
1218
1219 return None;
1220 }
1221
1222 /// Returns true if \p I is a memory terminator instruction like
1223 /// llvm.lifetime.end or free.
1224 bool isMemTerminatorInst(Instruction *I) const {
1225 IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
1226 return (II && II->getIntrinsicID() == Intrinsic::lifetime_end) ||
1227 isFreeCall(I, &TLI);
1228 }
1229
1230 /// Returns true if \p MaybeTerm is a memory terminator for \p Loc from
1231 /// instruction \p AccessI.
1232 bool isMemTerminator(const MemoryLocation &Loc, Instruction *AccessI,
1233 Instruction *MaybeTerm) {
1234 Optional<std::pair<MemoryLocation, bool>> MaybeTermLoc =
1235 getLocForTerminator(MaybeTerm);
1236
1237 if (!MaybeTermLoc)
1238 return false;
1239
1240 // If the terminator is a free-like call, all accesses to the underlying
1241 // object can be considered terminated.
1242 if (getUnderlyingObject(Loc.Ptr) !=
1243 getUnderlyingObject(MaybeTermLoc->first.Ptr))
1244 return false;
1245
1246 auto TermLoc = MaybeTermLoc->first;
1247 if (MaybeTermLoc->second) {
1248 const Value *LocUO = getUnderlyingObject(Loc.Ptr);
1249 return BatchAA.isMustAlias(TermLoc.Ptr, LocUO);
1250 }
1251 int64_t InstWriteOffset, DepWriteOffset;
1252 return isOverwrite(MaybeTerm, AccessI, TermLoc, Loc, DepWriteOffset,
1253 InstWriteOffset) == OW_Complete;
1254 }
1255
1256 // Returns true if \p Use may read from \p DefLoc.
1257 bool isReadClobber(const MemoryLocation &DefLoc, Instruction *UseInst) {
1258 if (isNoopIntrinsic(UseInst))
1259 return false;
1260
1261 // Monotonic or weaker atomic stores can be re-ordered and do not need to be
1262 // treated as read clobber.
1263 if (auto SI = dyn_cast<StoreInst>(UseInst))
1264 return isStrongerThan(SI->getOrdering(), AtomicOrdering::Monotonic);
1265
1266 if (!UseInst->mayReadFromMemory())
1267 return false;
1268
1269 if (auto *CB = dyn_cast<CallBase>(UseInst))
1270 if (CB->onlyAccessesInaccessibleMemory())
1271 return false;
1272
1273 // NOTE: For calls, the number of stores removed could be slightly improved
1274 // by using AA.callCapturesBefore(UseInst, DefLoc, &DT), but that showed to
1275 // be expensive compared to the benefits in practice. For now, avoid more
1276 // expensive analysis to limit compile-time.
1277 return isRefSet(BatchAA.getModRefInfo(UseInst, DefLoc));
1278 }
1279
1280 /// Returns true if a dependency between \p Current and \p KillingDef is
1281 /// guaranteed to be loop invariant for the loops that they are in. Either
1282 /// because they are known to be in the same block, in the same loop level or
1283 /// by guaranteeing that \p CurrentLoc only references a single MemoryLocation
1284 /// during execution of the containing function.
1285 bool isGuaranteedLoopIndependent(const Instruction *Current,
1286 const Instruction *KillingDef,
1287 const MemoryLocation &CurrentLoc) {
1288 // If the dependency is within the same block or loop level (being careful
1289 // of irreducible loops), we know that AA will return a valid result for the
1290 // memory dependency. (Both at the function level, outside of any loop,
1291 // would also be valid but we currently disable that to limit compile time).
1292 if (Current->getParent() == KillingDef->getParent())
1293 return true;
1294 const Loop *CurrentLI = LI.getLoopFor(Current->getParent());
1295 if (!ContainsIrreducibleLoops && CurrentLI &&
1296 CurrentLI == LI.getLoopFor(KillingDef->getParent()))
1297 return true;
1298 // Otherwise check the memory location is invariant to any loops.
1299 return isGuaranteedLoopInvariant(CurrentLoc.Ptr);
1300 }
1301
1302 /// Returns true if \p Ptr is guaranteed to be loop invariant for any possible
1303 /// loop. In particular, this guarantees that it only references a single
1304 /// MemoryLocation during execution of the containing function.
1305 bool isGuaranteedLoopInvariant(const Value *Ptr) {
1306 auto IsGuaranteedLoopInvariantBase = [this](const Value *Ptr) {
1307 Ptr = Ptr->stripPointerCasts();
1308 if (auto *I = dyn_cast<Instruction>(Ptr)) {
1309 if (isa<AllocaInst>(Ptr))
1310 return true;
1311
1312 if (isAllocLikeFn(I, &TLI))
1313 return true;
1314
1315 return false;
1316 }
1317 return true;
1318 };
1319
1320 Ptr = Ptr->stripPointerCasts();
1321 if (auto *I = dyn_cast<Instruction>(Ptr)) {
1322 if (I->getParent()->isEntryBlock())
1323 return true;
1324 }
1325 if (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
1326 return IsGuaranteedLoopInvariantBase(GEP->getPointerOperand()) &&
1327 GEP->hasAllConstantIndices();
1328 }
1329 return IsGuaranteedLoopInvariantBase(Ptr);
1330 }
1331
1332 // Find a MemoryDef writing to \p DefLoc and dominating \p StartAccess, with
1333 // no read access between them or on any other path to a function exit block
1334 // if \p DefLoc is not accessible after the function returns. If there is no
1335 // such MemoryDef, return None. The returned value may not (completely)
1336 // overwrite \p DefLoc. Currently we bail out when we encounter an aliasing
1337 // MemoryUse (read).
1338 Optional<MemoryAccess *>
1339 getDomMemoryDef(MemoryDef *KillingDef, MemoryAccess *StartAccess,
1340 const MemoryLocation &DefLoc, const Value *DefUO,
1341 unsigned &ScanLimit, unsigned &WalkerStepLimit,
1342 bool IsMemTerm, unsigned &PartialLimit) {
1343 if (ScanLimit == 0 || WalkerStepLimit == 0) {
1
Assuming 'ScanLimit' is not equal to 0
2
Assuming 'WalkerStepLimit' is not equal to 0
3
Taking false branch
1344 LLVM_DEBUG(dbgs() << "\n ... hit scan limit\n")do { } while (false);
1345 return None;
1346 }
1347
1348 MemoryAccess *Current = StartAccess;
1349 Instruction *KillingI = KillingDef->getMemoryInst();
1350 LLVM_DEBUG(dbgs() << " trying to get dominating access\n")do { } while (false);
4
Loop condition is false. Exiting loop
1351
1352 // Find the next clobbering Mod access for DefLoc, starting at StartAccess.
1353 Optional<MemoryLocation> CurrentLoc;
1354 for (;; Current = cast<MemoryDef>(Current)->getDefiningAccess()) {
5
Loop condition is true. Entering loop body
1355 LLVM_DEBUG({do { } while (false)
6
Loop condition is false. Exiting loop
1356 dbgs() << " visiting " << *Current;do { } while (false)
1357 if (!MSSA.isLiveOnEntryDef(Current) && isa<MemoryUseOrDef>(Current))do { } while (false)
1358 dbgs() << " (" << *cast<MemoryUseOrDef>(Current)->getMemoryInst()do { } while (false)
1359 << ")";do { } while (false)
1360 dbgs() << "\n";do { } while (false)
1361 })do { } while (false);
1362
1363 // Reached TOP.
1364 if (MSSA.isLiveOnEntryDef(Current)) {
7
Taking false branch
1365 LLVM_DEBUG(dbgs() << " ... found LiveOnEntryDef\n")do { } while (false);
1366 return None;
1367 }
1368
1369 // Cost of a step. Accesses in the same block are more likely to be valid
1370 // candidates for elimination, hence consider them cheaper.
1371 unsigned StepCost = KillingDef->getBlock() == Current->getBlock()
8
Assuming the condition is false
9
'?' condition is false
1372 ? MemorySSASameBBStepCost
1373 : MemorySSAOtherBBStepCost;
1374 if (WalkerStepLimit <= StepCost) {
10
Assuming 'WalkerStepLimit' is > 'StepCost'
11
Taking false branch
1375 LLVM_DEBUG(dbgs() << " ... hit walker step limit\n")do { } while (false);
1376 return None;
1377 }
1378 WalkerStepLimit -= StepCost;
1379
1380 // Return for MemoryPhis. They cannot be eliminated directly and the
1381 // caller is responsible for traversing them.
1382 if (isa<MemoryPhi>(Current)) {
12
Assuming 'Current' is not a 'MemoryPhi'
13
Taking false branch
1383 LLVM_DEBUG(dbgs() << " ... found MemoryPhi\n")do { } while (false);
1384 return Current;
1385 }
1386
1387 // Below, check if CurrentDef is a valid candidate to be eliminated by
1388 // KillingDef. If it is not, check the next candidate.
1389 MemoryDef *CurrentDef = cast<MemoryDef>(Current);
14
'Current' is a 'MemoryDef'
1390 Instruction *CurrentI = CurrentDef->getMemoryInst();
1391
1392 if (canSkipDef(CurrentDef, !isInvisibleToCallerBeforeRet(DefUO)))
15
Assuming the condition is false
16
Taking false branch
1393 continue;
1394
1395 // Before we try to remove anything, check for any extra throwing
1396 // instructions that block us from DSEing
1397 if (mayThrowBetween(KillingI, CurrentI, DefUO)) {
17
Taking false branch
1398 LLVM_DEBUG(dbgs() << " ... skip, may throw!\n")do { } while (false);
1399 return None;
1400 }
1401
1402 // Check for anything that looks like it will be a barrier to further
1403 // removal
1404 if (isDSEBarrier(DefUO, CurrentI)) {
18
Taking false branch
1405 LLVM_DEBUG(dbgs() << " ... skip, barrier\n")do { } while (false);
1406 return None;
1407 }
1408
1409 // If Current is known to be on path that reads DefLoc or is a read
1410 // clobber, bail out, as the path is not profitable. We skip this check
1411 // for intrinsic calls, because the code knows how to handle memcpy
1412 // intrinsics.
1413 if (!isa<IntrinsicInst>(CurrentI) && isReadClobber(DefLoc, CurrentI))
19
Assuming 'CurrentI' is not a 'IntrinsicInst'
20
Taking false branch
1414 return None;
1415
1416 // Quick check if there are direct uses that are read-clobbers.
1417 if (any_of(Current->uses(), [this, &DefLoc, StartAccess](Use &U) {
21
Taking false branch
1418 if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(U.getUser()))
1419 return !MSSA.dominates(StartAccess, UseOrDef) &&
1420 isReadClobber(DefLoc, UseOrDef->getMemoryInst());
1421 return false;
1422 })) {
1423 LLVM_DEBUG(dbgs() << " ... found a read clobber\n")do { } while (false);
1424 return None;
1425 }
1426
1427 // If Current cannot be analyzed or is not removable, check the next
1428 // candidate.
1429 if (!hasAnalyzableMemoryWrite(CurrentI, TLI) || !isRemovable(CurrentI))
22
Taking false branch
1430 continue;
1431
1432 // If Current does not have an analyzable write location, skip it
1433 CurrentLoc = getLocForWriteEx(CurrentI);
1434 if (!CurrentLoc)
23
Assuming the condition is false
24
Taking false branch
1435 continue;
1436
1437 // AliasAnalysis does not account for loops. Limit elimination to
1438 // candidates for which we can guarantee they always store to the same
1439 // memory location and not located in different loops.
1440 if (!isGuaranteedLoopIndependent(CurrentI, KillingI, *CurrentLoc)) {
25
Taking false branch
1441 LLVM_DEBUG(dbgs() << " ... not guaranteed loop independent\n")do { } while (false);
1442 WalkerStepLimit -= 1;
1443 continue;
1444 }
1445
1446 if (IsMemTerm) {
26
Assuming 'IsMemTerm' is false
27
Taking false branch
1447 // If the killing def is a memory terminator (e.g. lifetime.end), check
1448 // the next candidate if the current Current does not write the same
1449 // underlying object as the terminator.
1450 if (!isMemTerminator(*CurrentLoc, CurrentI, KillingI))
1451 continue;
1452 } else {
1453 int64_t InstWriteOffset, DepWriteOffset;
1454 auto OR = isOverwrite(KillingI, CurrentI, DefLoc, *CurrentLoc,
1455 DepWriteOffset, InstWriteOffset);
1456 // If Current does not write to the same object as KillingDef, check
1457 // the next candidate.
1458 if (OR == OW_Unknown)
28
Assuming 'OR' is not equal to OW_Unknown
29
Taking false branch
1459 continue;
1460 else if (OR == OW_MaybePartial) {
30
Assuming 'OR' is not equal to OW_MaybePartial
31
Taking false branch
1461 // If KillingDef only partially overwrites Current, check the next
1462 // candidate if the partial step limit is exceeded. This aggressively
1463 // limits the number of candidates for partial store elimination,
1464 // which are less likely to be removable in the end.
1465 if (PartialLimit <= 1) {
1466 WalkerStepLimit -= 1;
1467 continue;
1468 }
1469 PartialLimit -= 1;
1470 }
1471 }
1472 break;
32
Execution continues on line 1479
1473 };
1474
1475 // Accesses to objects accessible after the function returns can only be
1476 // eliminated if the access is killed along all paths to the exit. Collect
1477 // the blocks with killing (=completely overwriting MemoryDefs) and check if
1478 // they cover all paths from EarlierAccess to any function exit.
1479 SmallPtrSet<Instruction *, 16> KillingDefs;
1480 KillingDefs.insert(KillingDef->getMemoryInst());
1481 MemoryAccess *EarlierAccess = Current;
1482 Instruction *EarlierMemInst =
1483 cast<MemoryDef>(EarlierAccess)->getMemoryInst();
33
'EarlierAccess' is a 'MemoryDef'
1484 LLVM_DEBUG(dbgs() << " Checking for reads of " << *EarlierAccess << " ("do { } while (false)
34
Loop condition is false. Exiting loop
1485 << *EarlierMemInst << ")\n")do { } while (false);
1486
1487 SmallSetVector<MemoryAccess *, 32> WorkList;
1488 auto PushMemUses = [&WorkList](MemoryAccess *Acc) {
1489 for (Use &U : Acc->uses())
1490 WorkList.insert(cast<MemoryAccess>(U.getUser()));
1491 };
1492 PushMemUses(EarlierAccess);
1493
1494 // Optimistically collect all accesses for reads. If we do not find any
1495 // read clobbers, add them to the cache.
1496 SmallPtrSet<MemoryAccess *, 16> KnownNoReads;
1497 if (!EarlierMemInst->mayReadFromMemory())
35
Assuming the condition is false
36
Taking false branch
1498 KnownNoReads.insert(EarlierAccess);
1499 // Check if EarlierDef may be read.
1500 for (unsigned I = 0; I < WorkList.size(); I++) {
37
Assuming the condition is false
38
Loop condition is false. Execution continues on line 1613
1501 MemoryAccess *UseAccess = WorkList[I];
1502
1503 LLVM_DEBUG(dbgs() << " " << *UseAccess)do { } while (false);
1504 // Bail out if the number of accesses to check exceeds the scan limit.
1505 if (ScanLimit < (WorkList.size() - I)) {
1506 LLVM_DEBUG(dbgs() << "\n ... hit scan limit\n")do { } while (false);
1507 return None;
1508 }
1509 --ScanLimit;
1510 NumDomMemDefChecks++;
1511 KnownNoReads.insert(UseAccess);
1512
1513 if (isa<MemoryPhi>(UseAccess)) {
1514 if (any_of(KillingDefs, [this, UseAccess](Instruction *KI) {
1515 return DT.properlyDominates(KI->getParent(),
1516 UseAccess->getBlock());
1517 })) {
1518 LLVM_DEBUG(dbgs() << " ... skipping, dominated by killing block\n")do { } while (false);
1519 continue;
1520 }
1521 LLVM_DEBUG(dbgs() << "\n ... adding PHI uses\n")do { } while (false);
1522 PushMemUses(UseAccess);
1523 continue;
1524 }
1525
1526 Instruction *UseInst = cast<MemoryUseOrDef>(UseAccess)->getMemoryInst();
1527 LLVM_DEBUG(dbgs() << " (" << *UseInst << ")\n")do { } while (false);
1528
1529 if (any_of(KillingDefs, [this, UseInst](Instruction *KI) {
1530 return DT.dominates(KI, UseInst);
1531 })) {
1532 LLVM_DEBUG(dbgs() << " ... skipping, dominated by killing def\n")do { } while (false);
1533 continue;
1534 }
1535
1536 // A memory terminator kills all preceeding MemoryDefs and all succeeding
1537 // MemoryAccesses. We do not have to check it's users.
1538 if (isMemTerminator(*CurrentLoc, EarlierMemInst, UseInst)) {
1539 LLVM_DEBUG(do { } while (false)
1540 dbgs()do { } while (false)
1541 << " ... skipping, memterminator invalidates following accesses\n")do { } while (false);
1542 continue;
1543 }
1544
1545 if (isNoopIntrinsic(cast<MemoryUseOrDef>(UseAccess)->getMemoryInst())) {
1546 LLVM_DEBUG(dbgs() << " ... adding uses of intrinsic\n")do { } while (false);
1547 PushMemUses(UseAccess);
1548 continue;
1549 }
1550
1551 if (UseInst->mayThrow() && !isInvisibleToCallerBeforeRet(DefUO)) {
1552 LLVM_DEBUG(dbgs() << " ... found throwing instruction\n")do { } while (false);
1553 return None;
1554 }
1555
1556 // Uses which may read the original MemoryDef mean we cannot eliminate the
1557 // original MD. Stop walk.
1558 if (isReadClobber(*CurrentLoc, UseInst)) {
1559 LLVM_DEBUG(dbgs() << " ... found read clobber\n")do { } while (false);
1560 return None;
1561 }
1562
1563 // If this worklist walks back to the original memory access (and the
1564 // pointer is not guarenteed loop invariant) then we cannot assume that a
1565 // store kills itself.
1566 if (EarlierAccess == UseAccess &&
1567 !isGuaranteedLoopInvariant(CurrentLoc->Ptr)) {
1568 LLVM_DEBUG(dbgs() << " ... found not loop invariant self access\n")do { } while (false);
1569 return None;
1570 }
1571 // Otherwise, for the KillingDef and EarlierAccess we only have to check
1572 // if it reads the memory location.
1573 // TODO: It would probably be better to check for self-reads before
1574 // calling the function.
1575 if (KillingDef == UseAccess || EarlierAccess == UseAccess) {
1576 LLVM_DEBUG(dbgs() << " ... skipping killing def/dom access\n")do { } while (false);
1577 continue;
1578 }
1579
1580 // Check all uses for MemoryDefs, except for defs completely overwriting
1581 // the original location. Otherwise we have to check uses of *all*
1582 // MemoryDefs we discover, including non-aliasing ones. Otherwise we might
1583 // miss cases like the following
1584 // 1 = Def(LoE) ; <----- EarlierDef stores [0,1]
1585 // 2 = Def(1) ; (2, 1) = NoAlias, stores [2,3]
1586 // Use(2) ; MayAlias 2 *and* 1, loads [0, 3].
1587 // (The Use points to the *first* Def it may alias)
1588 // 3 = Def(1) ; <---- Current (3, 2) = NoAlias, (3,1) = MayAlias,
1589 // stores [0,1]
1590 if (MemoryDef *UseDef = dyn_cast<MemoryDef>(UseAccess)) {
1591 if (isCompleteOverwrite(*CurrentLoc, EarlierMemInst, UseInst)) {
1592 BasicBlock *MaybeKillingBlock = UseInst->getParent();
1593 if (PostOrderNumbers.find(MaybeKillingBlock)->second <
1594 PostOrderNumbers.find(EarlierAccess->getBlock())->second) {
1595 if (!isInvisibleToCallerAfterRet(DefUO)) {
1596 LLVM_DEBUG(dbgs()do { } while (false)
1597 << " ... found killing def " << *UseInst << "\n")do { } while (false);
1598 KillingDefs.insert(UseInst);
1599 }
1600 } else {
1601 LLVM_DEBUG(dbgs()do { } while (false)
1602 << " ... found preceeding def " << *UseInst << "\n")do { } while (false);
1603 return None;
1604 }
1605 } else
1606 PushMemUses(UseDef);
1607 }
1608 }
1609
1610 // For accesses to locations visible after the function returns, make sure
1611 // that the location is killed (=overwritten) along all paths from
1612 // EarlierAccess to the exit.
1613 if (!isInvisibleToCallerAfterRet(DefUO)) {
39
Assuming the condition is true
40
Taking true branch
1614 SmallPtrSet<BasicBlock *, 16> KillingBlocks;
1615 for (Instruction *KD : KillingDefs)
1616 KillingBlocks.insert(KD->getParent());
1617 assert(!KillingBlocks.empty() &&((void)0)
1618 "Expected at least a single killing block")((void)0);
1619
1620 // Find the common post-dominator of all killing blocks.
1621 BasicBlock *CommonPred = *KillingBlocks.begin();
1622 for (auto I = std::next(KillingBlocks.begin()), E = KillingBlocks.end();
41
Loop condition is true. Entering loop body
1623 I != E; I++) {
1624 if (!CommonPred)
42
Assuming 'CommonPred' is non-null
43
Taking false branch
1625 break;
1626 CommonPred = PDT.findNearestCommonDominator(CommonPred, *I);
44
Calling 'DominatorTreeBase::findNearestCommonDominator'
1627 }
1628
1629 // If CommonPred is in the set of killing blocks, just check if it
1630 // post-dominates EarlierAccess.
1631 if (KillingBlocks.count(CommonPred)) {
1632 if (PDT.dominates(CommonPred, EarlierAccess->getBlock()))
1633 return {EarlierAccess};
1634 return None;
1635 }
1636
1637 // If the common post-dominator does not post-dominate EarlierAccess,
1638 // there is a path from EarlierAccess to an exit not going through a
1639 // killing block.
1640 if (PDT.dominates(CommonPred, EarlierAccess->getBlock())) {
1641 SetVector<BasicBlock *> WorkList;
1642
1643 // If CommonPred is null, there are multiple exits from the function.
1644 // They all have to be added to the worklist.
1645 if (CommonPred)
1646 WorkList.insert(CommonPred);
1647 else
1648 for (BasicBlock *R : PDT.roots())
1649 WorkList.insert(R);
1650
1651 NumCFGTries++;
1652 // Check if all paths starting from an exit node go through one of the
1653 // killing blocks before reaching EarlierAccess.
1654 for (unsigned I = 0; I < WorkList.size(); I++) {
1655 NumCFGChecks++;
1656 BasicBlock *Current = WorkList[I];
1657 if (KillingBlocks.count(Current))
1658 continue;
1659 if (Current == EarlierAccess->getBlock())
1660 return None;
1661
1662 // EarlierAccess is reachable from the entry, so we don't have to
1663 // explore unreachable blocks further.
1664 if (!DT.isReachableFromEntry(Current))
1665 continue;
1666
1667 for (BasicBlock *Pred : predecessors(Current))
1668 WorkList.insert(Pred);
1669
1670 if (WorkList.size() >= MemorySSAPathCheckLimit)
1671 return None;
1672 }
1673 NumCFGSuccess++;
1674 return {EarlierAccess};
1675 }
1676 return None;
1677 }
1678
1679 // No aliasing MemoryUses of EarlierAccess found, EarlierAccess is
1680 // potentially dead.
1681 return {EarlierAccess};
1682 }
1683
1684 // Delete dead memory defs
1685 void deleteDeadInstruction(Instruction *SI) {
1686 MemorySSAUpdater Updater(&MSSA);
1687 SmallVector<Instruction *, 32> NowDeadInsts;
1688 NowDeadInsts.push_back(SI);
1689 --NumFastOther;
1690
1691 while (!NowDeadInsts.empty()) {
1692 Instruction *DeadInst = NowDeadInsts.pop_back_val();
1693 ++NumFastOther;
1694
1695 // Try to preserve debug information attached to the dead instruction.
1696 salvageDebugInfo(*DeadInst);
1697 salvageKnowledge(DeadInst);
1698
1699 // Remove the Instruction from MSSA.
1700 if (MemoryAccess *MA = MSSA.getMemoryAccess(DeadInst)) {
1701 if (MemoryDef *MD = dyn_cast<MemoryDef>(MA)) {
1702 SkipStores.insert(MD);
1703 }
1704 Updater.removeMemoryAccess(MA);
1705 }
1706
1707 auto I = IOLs.find(DeadInst->getParent());
1708 if (I != IOLs.end())
1709 I->second.erase(DeadInst);
1710 // Remove its operands
1711 for (Use &O : DeadInst->operands())
1712 if (Instruction *OpI = dyn_cast<Instruction>(O)) {
1713 O = nullptr;
1714 if (isInstructionTriviallyDead(OpI, &TLI))
1715 NowDeadInsts.push_back(OpI);
1716 }
1717
1718 DeadInst->eraseFromParent();
1719 }
1720 }
1721
1722 // Check for any extra throws between SI and NI that block DSE. This only
1723 // checks extra maythrows (those that aren't MemoryDef's). MemoryDef that may
1724 // throw are handled during the walk from one def to the next.
1725 bool mayThrowBetween(Instruction *SI, Instruction *NI,
1726 const Value *SILocUnd) {
1727 // First see if we can ignore it by using the fact that SI is an
1728 // alloca/alloca like object that is not visible to the caller during
1729 // execution of the function.
1730 if (SILocUnd && isInvisibleToCallerBeforeRet(SILocUnd))
1731 return false;
1732
1733 if (SI->getParent() == NI->getParent())
1734 return ThrowingBlocks.count(SI->getParent());
1735 return !ThrowingBlocks.empty();
1736 }
1737
1738 // Check if \p NI acts as a DSE barrier for \p SI. The following instructions
1739 // act as barriers:
1740 // * A memory instruction that may throw and \p SI accesses a non-stack
1741 // object.
1742 // * Atomic stores stronger that monotonic.
1743 bool isDSEBarrier(const Value *SILocUnd, Instruction *NI) {
1744 // If NI may throw it acts as a barrier, unless we are to an alloca/alloca
1745 // like object that does not escape.
1746 if (NI->mayThrow() && !isInvisibleToCallerBeforeRet(SILocUnd))
1747 return true;
1748
1749 // If NI is an atomic load/store stronger than monotonic, do not try to
1750 // eliminate/reorder it.
1751 if (NI->isAtomic()) {
1752 if (auto *LI = dyn_cast<LoadInst>(NI))
1753 return isStrongerThanMonotonic(LI->getOrdering());
1754 if (auto *SI = dyn_cast<StoreInst>(NI))
1755 return isStrongerThanMonotonic(SI->getOrdering());
1756 if (auto *ARMW = dyn_cast<AtomicRMWInst>(NI))
1757 return isStrongerThanMonotonic(ARMW->getOrdering());
1758 if (auto *CmpXchg = dyn_cast<AtomicCmpXchgInst>(NI))
1759 return isStrongerThanMonotonic(CmpXchg->getSuccessOrdering()) ||
1760 isStrongerThanMonotonic(CmpXchg->getFailureOrdering());
1761 llvm_unreachable("other instructions should be skipped in MemorySSA")__builtin_unreachable();
1762 }
1763 return false;
1764 }
1765
1766 /// Eliminate writes to objects that are not visible in the caller and are not
1767 /// accessed before returning from the function.
1768 bool eliminateDeadWritesAtEndOfFunction() {
1769 bool MadeChange = false;
1770 LLVM_DEBUG(do { } while (false)
1771 dbgs()do { } while (false)
1772 << "Trying to eliminate MemoryDefs at the end of the function\n")do { } while (false);
1773 for (int I = MemDefs.size() - 1; I >= 0; I--) {
1774 MemoryDef *Def = MemDefs[I];
1775 if (SkipStores.contains(Def) || !isRemovable(Def->getMemoryInst()))
1776 continue;
1777
1778 Instruction *DefI = Def->getMemoryInst();
1779 SmallVector<const Value *, 4> Pointers;
1780 auto DefLoc = getLocForWriteEx(DefI);
1781 if (!DefLoc)
1782 continue;
1783
1784 // NOTE: Currently eliminating writes at the end of a function is limited
1785 // to MemoryDefs with a single underlying object, to save compile-time. In
1786 // practice it appears the case with multiple underlying objects is very
1787 // uncommon. If it turns out to be important, we can use
1788 // getUnderlyingObjects here instead.
1789 const Value *UO = getUnderlyingObject(DefLoc->Ptr);
1790 if (!UO || !isInvisibleToCallerAfterRet(UO))
1791 continue;
1792
1793 if (isWriteAtEndOfFunction(Def)) {
1794 // See through pointer-to-pointer bitcasts
1795 LLVM_DEBUG(dbgs() << " ... MemoryDef is not accessed until the end "do { } while (false)
1796 "of the function\n")do { } while (false);
1797 deleteDeadInstruction(DefI);
1798 ++NumFastStores;
1799 MadeChange = true;
1800 }
1801 }
1802 return MadeChange;
1803 }
1804
1805 /// \returns true if \p Def is a no-op store, either because it
1806 /// directly stores back a loaded value or stores zero to a calloced object.
1807 bool storeIsNoop(MemoryDef *Def, const MemoryLocation &DefLoc,
1808 const Value *DefUO) {
1809 StoreInst *Store = dyn_cast<StoreInst>(Def->getMemoryInst());
1810 MemSetInst *MemSet = dyn_cast<MemSetInst>(Def->getMemoryInst());
1811 Constant *StoredConstant = nullptr;
1812 if (Store)
1813 StoredConstant = dyn_cast<Constant>(Store->getOperand(0));
1814 if (MemSet)
1815 StoredConstant = dyn_cast<Constant>(MemSet->getValue());
1816
1817 if (StoredConstant && StoredConstant->isNullValue()) {
1818 auto *DefUOInst = dyn_cast<Instruction>(DefUO);
1819 if (DefUOInst && isCallocLikeFn(DefUOInst, &TLI)) {
1820 auto *UnderlyingDef = cast<MemoryDef>(MSSA.getMemoryAccess(DefUOInst));
1821 // If UnderlyingDef is the clobbering access of Def, no instructions
1822 // between them can modify the memory location.
1823 auto *ClobberDef =
1824 MSSA.getSkipSelfWalker()->getClobberingMemoryAccess(Def);
1825 return UnderlyingDef == ClobberDef;
1826 }
1827 }
1828
1829 if (!Store)
1830 return false;
1831
1832 if (auto *LoadI = dyn_cast<LoadInst>(Store->getOperand(0))) {
1833 if (LoadI->getPointerOperand() == Store->getOperand(1)) {
1834 // Get the defining access for the load.
1835 auto *LoadAccess = MSSA.getMemoryAccess(LoadI)->getDefiningAccess();
1836 // Fast path: the defining accesses are the same.
1837 if (LoadAccess == Def->getDefiningAccess())
1838 return true;
1839
1840 // Look through phi accesses. Recursively scan all phi accesses by
1841 // adding them to a worklist. Bail when we run into a memory def that
1842 // does not match LoadAccess.
1843 SetVector<MemoryAccess *> ToCheck;
1844 MemoryAccess *Current =
1845 MSSA.getWalker()->getClobberingMemoryAccess(Def);
1846 // We don't want to bail when we run into the store memory def. But,
1847 // the phi access may point to it. So, pretend like we've already
1848 // checked it.
1849 ToCheck.insert(Def);
1850 ToCheck.insert(Current);
1851 // Start at current (1) to simulate already having checked Def.
1852 for (unsigned I = 1; I < ToCheck.size(); ++I) {
1853 Current = ToCheck[I];
1854 if (auto PhiAccess = dyn_cast<MemoryPhi>(Current)) {
1855 // Check all the operands.
1856 for (auto &Use : PhiAccess->incoming_values())
1857 ToCheck.insert(cast<MemoryAccess>(&Use));
1858 continue;
1859 }
1860
1861 // If we found a memory def, bail. This happens when we have an
1862 // unrelated write in between an otherwise noop store.
1863 assert(isa<MemoryDef>(Current) &&((void)0)
1864 "Only MemoryDefs should reach here.")((void)0);
1865 // TODO: Skip no alias MemoryDefs that have no aliasing reads.
1866 // We are searching for the definition of the store's destination.
1867 // So, if that is the same definition as the load, then this is a
1868 // noop. Otherwise, fail.
1869 if (LoadAccess != Current)
1870 return false;
1871 }
1872 return true;
1873 }
1874 }
1875
1876 return false;
1877 }
1878};
1879
1880static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
1881 DominatorTree &DT, PostDominatorTree &PDT,
1882 const TargetLibraryInfo &TLI,
1883 const LoopInfo &LI) {
1884 bool MadeChange = false;
1885
1886 DSEState State = DSEState::get(F, AA, MSSA, DT, PDT, TLI, LI);
1887 // For each store:
1888 for (unsigned I = 0; I < State.MemDefs.size(); I++) {
1889 MemoryDef *KillingDef = State.MemDefs[I];
1890 if (State.SkipStores.count(KillingDef))
1891 continue;
1892 Instruction *SI = KillingDef->getMemoryInst();
1893
1894 Optional<MemoryLocation> MaybeSILoc;
1895 if (State.isMemTerminatorInst(SI))
1896 MaybeSILoc = State.getLocForTerminator(SI).map(
1897 [](const std::pair<MemoryLocation, bool> &P) { return P.first; });
1898 else
1899 MaybeSILoc = State.getLocForWriteEx(SI);
1900
1901 if (!MaybeSILoc) {
1902 LLVM_DEBUG(dbgs() << "Failed to find analyzable write location for "do { } while (false)
1903 << *SI << "\n")do { } while (false);
1904 continue;
1905 }
1906 MemoryLocation SILoc = *MaybeSILoc;
1907 assert(SILoc.Ptr && "SILoc should not be null")((void)0);
1908 const Value *SILocUnd = getUnderlyingObject(SILoc.Ptr);
1909
1910 MemoryAccess *Current = KillingDef;
1911 LLVM_DEBUG(dbgs() << "Trying to eliminate MemoryDefs killed by "do { } while (false)
1912 << *Current << " (" << *SI << ")\n")do { } while (false);
1913
1914 unsigned ScanLimit = MemorySSAScanLimit;
1915 unsigned WalkerStepLimit = MemorySSAUpwardsStepLimit;
1916 unsigned PartialLimit = MemorySSAPartialStoreLimit;
1917 // Worklist of MemoryAccesses that may be killed by KillingDef.
1918 SetVector<MemoryAccess *> ToCheck;
1919
1920 if (SILocUnd)
1921 ToCheck.insert(KillingDef->getDefiningAccess());
1922
1923 bool Shortend = false;
1924 bool IsMemTerm = State.isMemTerminatorInst(SI);
1925 // Check if MemoryAccesses in the worklist are killed by KillingDef.
1926 for (unsigned I = 0; I < ToCheck.size(); I++) {
1927 Current = ToCheck[I];
1928 if (State.SkipStores.count(Current))
1929 continue;
1930
1931 Optional<MemoryAccess *> Next = State.getDomMemoryDef(
1932 KillingDef, Current, SILoc, SILocUnd, ScanLimit, WalkerStepLimit,
1933 IsMemTerm, PartialLimit);
1934
1935 if (!Next) {
1936 LLVM_DEBUG(dbgs() << " finished walk\n")do { } while (false);
1937 continue;
1938 }
1939
1940 MemoryAccess *EarlierAccess = *Next;
1941 LLVM_DEBUG(dbgs() << " Checking if we can kill " << *EarlierAccess)do { } while (false);
1942 if (isa<MemoryPhi>(EarlierAccess)) {
1943 LLVM_DEBUG(dbgs() << "\n ... adding incoming values to worklist\n")do { } while (false);
1944 for (Value *V : cast<MemoryPhi>(EarlierAccess)->incoming_values()) {
1945 MemoryAccess *IncomingAccess = cast<MemoryAccess>(V);
1946 BasicBlock *IncomingBlock = IncomingAccess->getBlock();
1947 BasicBlock *PhiBlock = EarlierAccess->getBlock();
1948
1949 // We only consider incoming MemoryAccesses that come before the
1950 // MemoryPhi. Otherwise we could discover candidates that do not
1951 // strictly dominate our starting def.
1952 if (State.PostOrderNumbers[IncomingBlock] >
1953 State.PostOrderNumbers[PhiBlock])
1954 ToCheck.insert(IncomingAccess);
1955 }
1956 continue;
1957 }
1958 auto *NextDef = cast<MemoryDef>(EarlierAccess);
1959 Instruction *NI = NextDef->getMemoryInst();
1960 LLVM_DEBUG(dbgs() << " (" << *NI << ")\n")do { } while (false);
1961 ToCheck.insert(NextDef->getDefiningAccess());
1962 NumGetDomMemoryDefPassed++;
1963
1964 if (!DebugCounter::shouldExecute(MemorySSACounter))
1965 continue;
1966
1967 MemoryLocation NILoc = *State.getLocForWriteEx(NI);
1968
1969 if (IsMemTerm) {
1970 const Value *NIUnd = getUnderlyingObject(NILoc.Ptr);
1971 if (SILocUnd != NIUnd)
1972 continue;
1973 LLVM_DEBUG(dbgs() << "DSE: Remove Dead Store:\n DEAD: " << *NIdo { } while (false)
1974 << "\n KILLER: " << *SI << '\n')do { } while (false);
1975 State.deleteDeadInstruction(NI);
1976 ++NumFastStores;
1977 MadeChange = true;
1978 } else {
1979 // Check if NI overwrites SI.
1980 int64_t InstWriteOffset, DepWriteOffset;
1981 OverwriteResult OR = State.isOverwrite(SI, NI, SILoc, NILoc,
1982 DepWriteOffset, InstWriteOffset);
1983 if (OR == OW_MaybePartial) {
1984 auto Iter = State.IOLs.insert(
1985 std::make_pair<BasicBlock *, InstOverlapIntervalsTy>(
1986 NI->getParent(), InstOverlapIntervalsTy()));
1987 auto &IOL = Iter.first->second;
1988 OR = isPartialOverwrite(SILoc, NILoc, DepWriteOffset, InstWriteOffset,
1989 NI, IOL);
1990 }
1991
1992 if (EnablePartialStoreMerging && OR == OW_PartialEarlierWithFullLater) {
1993 auto *Earlier = dyn_cast<StoreInst>(NI);
1994 auto *Later = dyn_cast<StoreInst>(SI);
1995 // We are re-using tryToMergePartialOverlappingStores, which requires
1996 // Earlier to domiante Later.
1997 // TODO: implement tryToMergeParialOverlappingStores using MemorySSA.
1998 if (Earlier && Later && DT.dominates(Earlier, Later)) {
1999 if (Constant *Merged = tryToMergePartialOverlappingStores(
2000 Earlier, Later, InstWriteOffset, DepWriteOffset, State.DL,
2001 State.BatchAA, &DT)) {
2002
2003 // Update stored value of earlier store to merged constant.
2004 Earlier->setOperand(0, Merged);
2005 ++NumModifiedStores;
2006 MadeChange = true;
2007
2008 Shortend = true;
2009 // Remove later store and remove any outstanding overlap intervals
2010 // for the updated store.
2011 State.deleteDeadInstruction(Later);
2012 auto I = State.IOLs.find(Earlier->getParent());
2013 if (I != State.IOLs.end())
2014 I->second.erase(Earlier);
2015 break;
2016 }
2017 }
2018 }
2019
2020 if (OR == OW_Complete) {
2021 LLVM_DEBUG(dbgs() << "DSE: Remove Dead Store:\n DEAD: " << *NIdo { } while (false)
2022 << "\n KILLER: " << *SI << '\n')do { } while (false);
2023 State.deleteDeadInstruction(NI);
2024 ++NumFastStores;
2025 MadeChange = true;
2026 }
2027 }
2028 }
2029
2030 // Check if the store is a no-op.
2031 if (!Shortend && isRemovable(SI) &&
2032 State.storeIsNoop(KillingDef, SILoc, SILocUnd)) {
2033 LLVM_DEBUG(dbgs() << "DSE: Remove No-Op Store:\n DEAD: " << *SI << '\n')do { } while (false);
2034 State.deleteDeadInstruction(SI);
2035 NumRedundantStores++;
2036 MadeChange = true;
2037 continue;
2038 }
2039 }
2040
2041 if (EnablePartialOverwriteTracking)
2042 for (auto &KV : State.IOLs)
2043 MadeChange |= removePartiallyOverlappedStores(State.DL, KV.second, TLI);
2044
2045 MadeChange |= State.eliminateDeadWritesAtEndOfFunction();
2046 return MadeChange;
2047}
2048} // end anonymous namespace
2049
2050//===----------------------------------------------------------------------===//
2051// DSE Pass
2052//===----------------------------------------------------------------------===//
2053PreservedAnalyses DSEPass::run(Function &F, FunctionAnalysisManager &AM) {
2054 AliasAnalysis &AA = AM.getResult<AAManager>(F);
2055 const TargetLibraryInfo &TLI = AM.getResult<TargetLibraryAnalysis>(F);
2056 DominatorTree &DT = AM.getResult<DominatorTreeAnalysis>(F);
2057 MemorySSA &MSSA = AM.getResult<MemorySSAAnalysis>(F).getMSSA();
2058 PostDominatorTree &PDT = AM.getResult<PostDominatorTreeAnalysis>(F);
2059 LoopInfo &LI = AM.getResult<LoopAnalysis>(F);
2060
2061 bool Changed = eliminateDeadStores(F, AA, MSSA, DT, PDT, TLI, LI);
2062
2063#ifdef LLVM_ENABLE_STATS0
2064 if (AreStatisticsEnabled())
2065 for (auto &I : instructions(F))
2066 NumRemainingStores += isa<StoreInst>(&I);
2067#endif
2068
2069 if (!Changed)
2070 return PreservedAnalyses::all();
2071
2072 PreservedAnalyses PA;
2073 PA.preserveSet<CFGAnalyses>();
2074 PA.preserve<MemorySSAAnalysis>();
2075 PA.preserve<LoopAnalysis>();
2076 return PA;
2077}
2078
2079namespace {
2080
2081/// A legacy pass for the legacy pass manager that wraps \c DSEPass.
2082class DSELegacyPass : public FunctionPass {
2083public:
2084 static char ID; // Pass identification, replacement for typeid
2085
2086 DSELegacyPass() : FunctionPass(ID) {
2087 initializeDSELegacyPassPass(*PassRegistry::getPassRegistry());
2088 }
2089
2090 bool runOnFunction(Function &F) override {
2091 if (skipFunction(F))
2092 return false;
2093
2094 AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
2095 DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2096 const TargetLibraryInfo &TLI =
2097 getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
2098 MemorySSA &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA();
2099 PostDominatorTree &PDT =
2100 getAnalysis<PostDominatorTreeWrapperPass>().getPostDomTree();
2101 LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
2102
2103 bool Changed = eliminateDeadStores(F, AA, MSSA, DT, PDT, TLI, LI);
2104
2105#ifdef LLVM_ENABLE_STATS0
2106 if (AreStatisticsEnabled())
2107 for (auto &I : instructions(F))
2108 NumRemainingStores += isa<StoreInst>(&I);
2109#endif
2110
2111 return Changed;
2112 }
2113
2114 void getAnalysisUsage(AnalysisUsage &AU) const override {
2115 AU.setPreservesCFG();
2116 AU.addRequired<AAResultsWrapperPass>();
2117 AU.addRequired<TargetLibraryInfoWrapperPass>();
2118 AU.addPreserved<GlobalsAAWrapperPass>();
2119 AU.addRequired<DominatorTreeWrapperPass>();
2120 AU.addPreserved<DominatorTreeWrapperPass>();
2121 AU.addRequired<PostDominatorTreeWrapperPass>();
2122 AU.addRequired<MemorySSAWrapperPass>();
2123 AU.addPreserved<PostDominatorTreeWrapperPass>();
2124 AU.addPreserved<MemorySSAWrapperPass>();
2125 AU.addRequired<LoopInfoWrapperPass>();
2126 AU.addPreserved<LoopInfoWrapperPass>();
2127 }
2128};
2129
2130} // end anonymous namespace
2131
2132char DSELegacyPass::ID = 0;
2133
2134INITIALIZE_PASS_BEGIN(DSELegacyPass, "dse", "Dead Store Elimination", false,static void *initializeDSELegacyPassPassOnce(PassRegistry &
Registry) {
2135 false)static void *initializeDSELegacyPassPassOnce(PassRegistry &
Registry) {
2136INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
2137INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)initializePostDominatorTreeWrapperPassPass(Registry);
2138INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)initializeAAResultsWrapperPassPass(Registry);
2139INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)initializeGlobalsAAWrapperPassPass(Registry);
2140INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)initializeMemorySSAWrapperPassPass(Registry);
2141INITIALIZE_PASS_DEPENDENCY(MemoryDependenceWrapperPass)initializeMemoryDependenceWrapperPassPass(Registry);
2142INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
2143INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
2144INITIALIZE_PASS_END(DSELegacyPass, "dse", "Dead Store Elimination", false,PassInfo *PI = new PassInfo( "Dead Store Elimination", "dse",
&DSELegacyPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<DSELegacyPass>), false, false); Registry.registerPass(
*PI, true); return PI; } static llvm::once_flag InitializeDSELegacyPassPassFlag
; void llvm::initializeDSELegacyPassPass(PassRegistry &Registry
) { llvm::call_once(InitializeDSELegacyPassPassFlag, initializeDSELegacyPassPassOnce
, std::ref(Registry)); }
2145 false)PassInfo *PI = new PassInfo( "Dead Store Elimination", "dse",
&DSELegacyPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<DSELegacyPass>), false, false); Registry.registerPass(
*PI, true); return PI; } static llvm::once_flag InitializeDSELegacyPassPassFlag
; void llvm::initializeDSELegacyPassPass(PassRegistry &Registry
) { llvm::call_once(InitializeDSELegacyPassPassFlag, initializeDSELegacyPassPassOnce
, std::ref(Registry)); }
2146
2147FunctionPass *llvm::createDeadStoreEliminationPass() {
2148 return new DSELegacyPass();
2149}

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support/GenericDomTree.h

1//===- GenericDomTree.h - Generic dominator trees for graphs ----*- C++ -*-===//
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/// \file
9///
10/// This file defines a set of templates that efficiently compute a dominator
11/// tree over a generic graph. This is used typically in LLVM for fast
12/// dominance queries on the CFG, but is fully generic w.r.t. the underlying
13/// graph types.
14///
15/// Unlike ADT/* graph algorithms, generic dominator tree has more requirements
16/// on the graph's NodeRef. The NodeRef should be a pointer and,
17/// NodeRef->getParent() must return the parent node that is also a pointer.
18///
19/// FIXME: Maybe GenericDomTree needs a TreeTraits, instead of GraphTraits.
20///
21//===----------------------------------------------------------------------===//
22
23#ifndef LLVM_SUPPORT_GENERICDOMTREE_H
24#define LLVM_SUPPORT_GENERICDOMTREE_H
25
26#include "llvm/ADT/DenseMap.h"
27#include "llvm/ADT/GraphTraits.h"
28#include "llvm/ADT/STLExtras.h"
29#include "llvm/ADT/SmallPtrSet.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/Support/CFGDiff.h"
32#include "llvm/Support/CFGUpdate.h"
33#include "llvm/Support/raw_ostream.h"
34#include <algorithm>
35#include <cassert>
36#include <cstddef>
37#include <iterator>
38#include <memory>
39#include <type_traits>
40#include <utility>
41
42namespace llvm {
43
44template <typename NodeT, bool IsPostDom>
45class DominatorTreeBase;
46
47namespace DomTreeBuilder {
48template <typename DomTreeT>
49struct SemiNCAInfo;
50} // namespace DomTreeBuilder
51
52/// Base class for the actual dominator tree node.
53template <class NodeT> class DomTreeNodeBase {
54 friend class PostDominatorTree;
55 friend class DominatorTreeBase<NodeT, false>;
56 friend class DominatorTreeBase<NodeT, true>;
57 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase<NodeT, false>>;
58 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase<NodeT, true>>;
59
60 NodeT *TheBB;
61 DomTreeNodeBase *IDom;
62 unsigned Level;
63 SmallVector<DomTreeNodeBase *, 4> Children;
64 mutable unsigned DFSNumIn = ~0;
65 mutable unsigned DFSNumOut = ~0;
66
67 public:
68 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase *iDom)
69 : TheBB(BB), IDom(iDom), Level(IDom ? IDom->Level + 1 : 0) {}
70
71 using iterator = typename SmallVector<DomTreeNodeBase *, 4>::iterator;
72 using const_iterator =
73 typename SmallVector<DomTreeNodeBase *, 4>::const_iterator;
74
75 iterator begin() { return Children.begin(); }
76 iterator end() { return Children.end(); }
77 const_iterator begin() const { return Children.begin(); }
78 const_iterator end() const { return Children.end(); }
79
80 DomTreeNodeBase *const &back() const { return Children.back(); }
81 DomTreeNodeBase *&back() { return Children.back(); }
82
83 iterator_range<iterator> children() { return make_range(begin(), end()); }
84 iterator_range<const_iterator> children() const {
85 return make_range(begin(), end());
86 }
87
88 NodeT *getBlock() const { return TheBB; }
89 DomTreeNodeBase *getIDom() const { return IDom; }
90 unsigned getLevel() const { return Level; }
91
92 std::unique_ptr<DomTreeNodeBase> addChild(
93 std::unique_ptr<DomTreeNodeBase> C) {
94 Children.push_back(C.get());
95 return C;
96 }
97
98 bool isLeaf() const { return Children.empty(); }
99 size_t getNumChildren() const { return Children.size(); }
100
101 void clearAllChildren() { Children.clear(); }
102
103 bool compare(const DomTreeNodeBase *Other) const {
104 if (getNumChildren() != Other->getNumChildren())
105 return true;
106
107 if (Level != Other->Level) return true;
108
109 SmallPtrSet<const NodeT *, 4> OtherChildren;
110 for (const DomTreeNodeBase *I : *Other) {
111 const NodeT *Nd = I->getBlock();
112 OtherChildren.insert(Nd);
113 }
114
115 for (const DomTreeNodeBase *I : *this) {
116 const NodeT *N = I->getBlock();
117 if (OtherChildren.count(N) == 0)
118 return true;
119 }
120 return false;
121 }
122
123 void setIDom(DomTreeNodeBase *NewIDom) {
124 assert(IDom && "No immediate dominator?")((void)0);
125 if (IDom == NewIDom) return;
126
127 auto I = find(IDom->Children, this);
128 assert(I != IDom->Children.end() &&((void)0)
129 "Not in immediate dominator children set!")((void)0);
130 // I am no longer your child...
131 IDom->Children.erase(I);
132
133 // Switch to new dominator
134 IDom = NewIDom;
135 IDom->Children.push_back(this);
136
137 UpdateLevel();
138 }
139
140 /// getDFSNumIn/getDFSNumOut - These return the DFS visitation order for nodes
141 /// in the dominator tree. They are only guaranteed valid if
142 /// updateDFSNumbers() has been called.
143 unsigned getDFSNumIn() const { return DFSNumIn; }
144 unsigned getDFSNumOut() const { return DFSNumOut; }
145
146private:
147 // Return true if this node is dominated by other. Use this only if DFS info
148 // is valid.
149 bool DominatedBy(const DomTreeNodeBase *other) const {
150 return this->DFSNumIn >= other->DFSNumIn &&
151 this->DFSNumOut <= other->DFSNumOut;
152 }
153
154 void UpdateLevel() {
155 assert(IDom)((void)0);
156 if (Level == IDom->Level + 1) return;
157
158 SmallVector<DomTreeNodeBase *, 64> WorkStack = {this};
159
160 while (!WorkStack.empty()) {
161 DomTreeNodeBase *Current = WorkStack.pop_back_val();
162 Current->Level = Current->IDom->Level + 1;
163
164 for (DomTreeNodeBase *C : *Current) {
165 assert(C->IDom)((void)0);
166 if (C->Level != C->IDom->Level + 1) WorkStack.push_back(C);
167 }
168 }
169 }
170};
171
172template <class NodeT>
173raw_ostream &operator<<(raw_ostream &O, const DomTreeNodeBase<NodeT> *Node) {
174 if (Node->getBlock())
175 Node->getBlock()->printAsOperand(O, false);
176 else
177 O << " <<exit node>>";
178
179 O << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "} ["
180 << Node->getLevel() << "]\n";
181
182 return O;
183}
184
185template <class NodeT>
186void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &O,
187 unsigned Lev) {
188 O.indent(2 * Lev) << "[" << Lev << "] " << N;
189 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
190 E = N->end();
191 I != E; ++I)
192 PrintDomTree<NodeT>(*I, O, Lev + 1);
193}
194
195namespace DomTreeBuilder {
196// The routines below are provided in a separate header but referenced here.
197template <typename DomTreeT>
198void Calculate(DomTreeT &DT);
199
200template <typename DomTreeT>
201void CalculateWithUpdates(DomTreeT &DT,
202 ArrayRef<typename DomTreeT::UpdateType> Updates);
203
204template <typename DomTreeT>
205void InsertEdge(DomTreeT &DT, typename DomTreeT::NodePtr From,
206 typename DomTreeT::NodePtr To);
207
208template <typename DomTreeT>
209void DeleteEdge(DomTreeT &DT, typename DomTreeT::NodePtr From,
210 typename DomTreeT::NodePtr To);
211
212template <typename DomTreeT>
213void ApplyUpdates(DomTreeT &DT,
214 GraphDiff<typename DomTreeT::NodePtr,
215 DomTreeT::IsPostDominator> &PreViewCFG,
216 GraphDiff<typename DomTreeT::NodePtr,
217 DomTreeT::IsPostDominator> *PostViewCFG);
218
219template <typename DomTreeT>
220bool Verify(const DomTreeT &DT, typename DomTreeT::VerificationLevel VL);
221} // namespace DomTreeBuilder
222
223/// Core dominator tree base class.
224///
225/// This class is a generic template over graph nodes. It is instantiated for
226/// various graphs in the LLVM IR or in the code generator.
227template <typename NodeT, bool IsPostDom>
228class DominatorTreeBase {
229 public:
230 static_assert(std::is_pointer<typename GraphTraits<NodeT *>::NodeRef>::value,
231 "Currently DominatorTreeBase supports only pointer nodes");
232 using NodeType = NodeT;
233 using NodePtr = NodeT *;
234 using ParentPtr = decltype(std::declval<NodeT *>()->getParent());
235 static_assert(std::is_pointer<ParentPtr>::value,
236 "Currently NodeT's parent must be a pointer type");
237 using ParentType = std::remove_pointer_t<ParentPtr>;
238 static constexpr bool IsPostDominator = IsPostDom;
239
240 using UpdateType = cfg::Update<NodePtr>;
241 using UpdateKind = cfg::UpdateKind;
242 static constexpr UpdateKind Insert = UpdateKind::Insert;
243 static constexpr UpdateKind Delete = UpdateKind::Delete;
244
245 enum class VerificationLevel { Fast, Basic, Full };
246
247protected:
248 // Dominators always have a single root, postdominators can have more.
249 SmallVector<NodeT *, IsPostDom ? 4 : 1> Roots;
250
251 using DomTreeNodeMapType =
252 DenseMap<NodeT *, std::unique_ptr<DomTreeNodeBase<NodeT>>>;
253 DomTreeNodeMapType DomTreeNodes;
254 DomTreeNodeBase<NodeT> *RootNode = nullptr;
255 ParentPtr Parent = nullptr;
256
257 mutable bool DFSInfoValid = false;
258 mutable unsigned int SlowQueries = 0;
259
260 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase>;
261
262 public:
263 DominatorTreeBase() {}
264
265 DominatorTreeBase(DominatorTreeBase &&Arg)
266 : Roots(std::move(Arg.Roots)),
267 DomTreeNodes(std::move(Arg.DomTreeNodes)),
268 RootNode(Arg.RootNode),
269 Parent(Arg.Parent),
270 DFSInfoValid(Arg.DFSInfoValid),
271 SlowQueries(Arg.SlowQueries) {
272 Arg.wipe();
273 }
274
275 DominatorTreeBase &operator=(DominatorTreeBase &&RHS) {
276 Roots = std::move(RHS.Roots);
277 DomTreeNodes = std::move(RHS.DomTreeNodes);
278 RootNode = RHS.RootNode;
279 Parent = RHS.Parent;
280 DFSInfoValid = RHS.DFSInfoValid;
281 SlowQueries = RHS.SlowQueries;
282 RHS.wipe();
283 return *this;
284 }
285
286 DominatorTreeBase(const DominatorTreeBase &) = delete;
287 DominatorTreeBase &operator=(const DominatorTreeBase &) = delete;
288
289 /// Iteration over roots.
290 ///
291 /// This may include multiple blocks if we are computing post dominators.
292 /// For forward dominators, this will always be a single block (the entry
293 /// block).
294 using root_iterator = typename SmallVectorImpl<NodeT *>::iterator;
295 using const_root_iterator = typename SmallVectorImpl<NodeT *>::const_iterator;
296
297 root_iterator root_begin() { return Roots.begin(); }
298 const_root_iterator root_begin() const { return Roots.begin(); }
299 root_iterator root_end() { return Roots.end(); }
300 const_root_iterator root_end() const { return Roots.end(); }
301
302 size_t root_size() const { return Roots.size(); }
303
304 iterator_range<root_iterator> roots() {
305 return make_range(root_begin(), root_end());
306 }
307 iterator_range<const_root_iterator> roots() const {
308 return make_range(root_begin(), root_end());
309 }
310
311 /// isPostDominator - Returns true if analysis based of postdoms
312 ///
313 bool isPostDominator() const { return IsPostDominator; }
46
Returning the value 1 (loaded from 'IsPostDominator'), which participates in a condition later
314
315 /// compare - Return false if the other dominator tree base matches this
316 /// dominator tree base. Otherwise return true.
317 bool compare(const DominatorTreeBase &Other) const {
318 if (Parent != Other.Parent) return true;
319
320 if (Roots.size() != Other.Roots.size())
321 return true;
322
323 if (!std::is_permutation(Roots.begin(), Roots.end(), Other.Roots.begin()))
324 return true;
325
326 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
327 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
328 return true;
329
330 for (const auto &DomTreeNode : DomTreeNodes) {
331 NodeT *BB = DomTreeNode.first;
332 typename DomTreeNodeMapType::const_iterator OI =
333 OtherDomTreeNodes.find(BB);
334 if (OI == OtherDomTreeNodes.end())
335 return true;
336
337 DomTreeNodeBase<NodeT> &MyNd = *DomTreeNode.second;
338 DomTreeNodeBase<NodeT> &OtherNd = *OI->second;
339
340 if (MyNd.compare(&OtherNd))
341 return true;
342 }
343
344 return false;
345 }
346
347 /// getNode - return the (Post)DominatorTree node for the specified basic
348 /// block. This is the same as using operator[] on this class. The result
349 /// may (but is not required to) be null for a forward (backwards)
350 /// statically unreachable block.
351 DomTreeNodeBase<NodeT> *getNode(const NodeT *BB) const {
352 auto I = DomTreeNodes.find(BB);
353 if (I != DomTreeNodes.end())
50
Calling 'operator!='
56
Returning from 'operator!='
57
Taking true branch
354 return I->second.get();
58
Returning pointer
355 return nullptr;
356 }
357
358 /// See getNode.
359 DomTreeNodeBase<NodeT> *operator[](const NodeT *BB) const {
360 return getNode(BB);
361 }
362
363 /// getRootNode - This returns the entry node for the CFG of the function. If
364 /// this tree represents the post-dominance relations for a function, however,
365 /// this root may be a node with the block == NULL. This is the case when
366 /// there are multiple exit nodes from a particular function. Consumers of
367 /// post-dominance information must be capable of dealing with this
368 /// possibility.
369 ///
370 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
371 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
372
373 /// Get all nodes dominated by R, including R itself.
374 void getDescendants(NodeT *R, SmallVectorImpl<NodeT *> &Result) const {
375 Result.clear();
376 const DomTreeNodeBase<NodeT> *RN = getNode(R);
377 if (!RN)
378 return; // If R is unreachable, it will not be present in the DOM tree.
379 SmallVector<const DomTreeNodeBase<NodeT> *, 8> WL;
380 WL.push_back(RN);
381
382 while (!WL.empty()) {
383 const DomTreeNodeBase<NodeT> *N = WL.pop_back_val();
384 Result.push_back(N->getBlock());
385 WL.append(N->begin(), N->end());
386 }
387 }
388
389 /// properlyDominates - Returns true iff A dominates B and A != B.
390 /// Note that this is not a constant time operation!
391 ///
392 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
393 const DomTreeNodeBase<NodeT> *B) const {
394 if (!A || !B)
395 return false;
396 if (A == B)
397 return false;
398 return dominates(A, B);
399 }
400
401 bool properlyDominates(const NodeT *A, const NodeT *B) const;
402
403 /// isReachableFromEntry - Return true if A is dominated by the entry
404 /// block of the function containing it.
405 bool isReachableFromEntry(const NodeT *A) const {
406 assert(!this->isPostDominator() &&((void)0)
407 "This is not implemented for post dominators")((void)0);
408 return isReachableFromEntry(getNode(const_cast<NodeT *>(A)));
409 }
410
411 bool isReachableFromEntry(const DomTreeNodeBase<NodeT> *A) const { return A; }
412
413 /// dominates - Returns true iff A dominates B. Note that this is not a
414 /// constant time operation!
415 ///
416 bool dominates(const DomTreeNodeBase<NodeT> *A,
417 const DomTreeNodeBase<NodeT> *B) const {
418 // A node trivially dominates itself.
419 if (B == A)
420 return true;
421
422 // An unreachable node is dominated by anything.
423 if (!isReachableFromEntry(B))
424 return true;
425
426 // And dominates nothing.
427 if (!isReachableFromEntry(A))
428 return false;
429
430 if (B->getIDom() == A) return true;
431
432 if (A->getIDom() == B) return false;
433
434 // A can only dominate B if it is higher in the tree.
435 if (A->getLevel() >= B->getLevel()) return false;
436
437 // Compare the result of the tree walk and the dfs numbers, if expensive
438 // checks are enabled.
439#ifdef EXPENSIVE_CHECKS
440 assert((!DFSInfoValid ||((void)0)
441 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) &&((void)0)
442 "Tree walk disagrees with dfs numbers!")((void)0);
443#endif
444
445 if (DFSInfoValid)
446 return B->DominatedBy(A);
447
448 // If we end up with too many slow queries, just update the
449 // DFS numbers on the theory that we are going to keep querying.
450 SlowQueries++;
451 if (SlowQueries > 32) {
452 updateDFSNumbers();
453 return B->DominatedBy(A);
454 }
455
456 return dominatedBySlowTreeWalk(A, B);
457 }
458
459 bool dominates(const NodeT *A, const NodeT *B) const;
460
461 NodeT *getRoot() const {
462 assert(this->Roots.size() == 1 && "Should always have entry node!")((void)0);
463 return this->Roots[0];
464 }
465
466 /// Find nearest common dominator basic block for basic block A and B. A and B
467 /// must have tree nodes.
468 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) const {
469 assert(A && B && "Pointers are not valid")((void)0);
470 assert(A->getParent() == B->getParent() &&((void)0)
471 "Two blocks are not in same function")((void)0);
472
473 // If either A or B is a entry block then it is nearest common dominator
474 // (for forward-dominators).
475 if (!isPostDominator()) {
45
Calling 'DominatorTreeBase::isPostDominator'
47
Returning from 'DominatorTreeBase::isPostDominator'
48
Taking false branch
476 NodeT &Entry = A->getParent()->front();
477 if (A == &Entry || B == &Entry)
478 return &Entry;
479 }
480
481 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
49
Calling 'DominatorTreeBase::getNode'
59
Returning from 'DominatorTreeBase::getNode'
60
'NodeA' initialized here
482 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
483 assert(NodeA && "A must be in the tree")((void)0);
484 assert(NodeB && "B must be in the tree")((void)0);
485
486 // Use level information to go up the tree until the levels match. Then
487 // continue going up til we arrive at the same node.
488 while (NodeA != NodeB) {
61
Assuming 'NodeA' is equal to 'NodeB'
62
Loop condition is false. Execution continues on line 494
489 if (NodeA->getLevel() < NodeB->getLevel()) std::swap(NodeA, NodeB);
490
491 NodeA = NodeA->IDom;
492 }
493
494 return NodeA->getBlock();
63
Called C++ object pointer is null
495 }
496
497 const NodeT *findNearestCommonDominator(const NodeT *A,
498 const NodeT *B) const {
499 // Cast away the const qualifiers here. This is ok since
500 // const is re-introduced on the return type.
501 return findNearestCommonDominator(const_cast<NodeT *>(A),
502 const_cast<NodeT *>(B));
503 }
504
505 bool isVirtualRoot(const DomTreeNodeBase<NodeT> *A) const {
506 return isPostDominator() && !A->getBlock();
507 }
508
509 //===--------------------------------------------------------------------===//
510 // API to update (Post)DominatorTree information based on modifications to
511 // the CFG...
512
513 /// Inform the dominator tree about a sequence of CFG edge insertions and
514 /// deletions and perform a batch update on the tree.
515 ///
516 /// This function should be used when there were multiple CFG updates after
517 /// the last dominator tree update. It takes care of performing the updates
518 /// in sync with the CFG and optimizes away the redundant operations that
519 /// cancel each other.
520 /// The functions expects the sequence of updates to be balanced. Eg.:
521 /// - {{Insert, A, B}, {Delete, A, B}, {Insert, A, B}} is fine, because
522 /// logically it results in a single insertions.
523 /// - {{Insert, A, B}, {Insert, A, B}} is invalid, because it doesn't make
524 /// sense to insert the same edge twice.
525 ///
526 /// What's more, the functions assumes that it's safe to ask every node in the
527 /// CFG about its children and inverse children. This implies that deletions
528 /// of CFG edges must not delete the CFG nodes before calling this function.
529 ///
530 /// The applyUpdates function can reorder the updates and remove redundant
531 /// ones internally. The batch updater is also able to detect sequences of
532 /// zero and exactly one update -- it's optimized to do less work in these
533 /// cases.
534 ///
535 /// Note that for postdominators it automatically takes care of applying
536 /// updates on reverse edges internally (so there's no need to swap the
537 /// From and To pointers when constructing DominatorTree::UpdateType).
538 /// The type of updates is the same for DomTreeBase<T> and PostDomTreeBase<T>
539 /// with the same template parameter T.
540 ///
541 /// \param Updates An unordered sequence of updates to perform. The current
542 /// CFG and the reverse of these updates provides the pre-view of the CFG.
543 ///
544 void applyUpdates(ArrayRef<UpdateType> Updates) {
545 GraphDiff<NodePtr, IsPostDominator> PreViewCFG(
546 Updates, /*ReverseApplyUpdates=*/true);
547 DomTreeBuilder::ApplyUpdates(*this, PreViewCFG, nullptr);
548 }
549
550 /// \param Updates An unordered sequence of updates to perform. The current
551 /// CFG and the reverse of these updates provides the pre-view of the CFG.
552 /// \param PostViewUpdates An unordered sequence of update to perform in order
553 /// to obtain a post-view of the CFG. The DT will be updated assuming the
554 /// obtained PostViewCFG is the desired end state.
555 void applyUpdates(ArrayRef<UpdateType> Updates,
556 ArrayRef<UpdateType> PostViewUpdates) {
557 if (Updates.empty()) {
558 GraphDiff<NodePtr, IsPostDom> PostViewCFG(PostViewUpdates);
559 DomTreeBuilder::ApplyUpdates(*this, PostViewCFG, &PostViewCFG);
560 } else {
561 // PreViewCFG needs to merge Updates and PostViewCFG. The updates in
562 // Updates need to be reversed, and match the direction in PostViewCFG.
563 // The PostViewCFG is created with updates reversed (equivalent to changes
564 // made to the CFG), so the PreViewCFG needs all the updates reverse
565 // applied.
566 SmallVector<UpdateType> AllUpdates(Updates.begin(), Updates.end());
567 append_range(AllUpdates, PostViewUpdates);
568 GraphDiff<NodePtr, IsPostDom> PreViewCFG(AllUpdates,
569 /*ReverseApplyUpdates=*/true);
570 GraphDiff<NodePtr, IsPostDom> PostViewCFG(PostViewUpdates);
571 DomTreeBuilder::ApplyUpdates(*this, PreViewCFG, &PostViewCFG);
572 }
573 }
574
575 /// Inform the dominator tree about a CFG edge insertion and update the tree.
576 ///
577 /// This function has to be called just before or just after making the update
578 /// on the actual CFG. There cannot be any other updates that the dominator
579 /// tree doesn't know about.
580 ///
581 /// Note that for postdominators it automatically takes care of inserting
582 /// a reverse edge internally (so there's no need to swap the parameters).
583 ///
584 void insertEdge(NodeT *From, NodeT *To) {
585 assert(From)((void)0);
586 assert(To)((void)0);
587 assert(From->getParent() == Parent)((void)0);
588 assert(To->getParent() == Parent)((void)0);
589 DomTreeBuilder::InsertEdge(*this, From, To);
590 }
591
592 /// Inform the dominator tree about a CFG edge deletion and update the tree.
593 ///
594 /// This function has to be called just after making the update on the actual
595 /// CFG. An internal functions checks if the edge doesn't exist in the CFG in
596 /// DEBUG mode. There cannot be any other updates that the
597 /// dominator tree doesn't know about.
598 ///
599 /// Note that for postdominators it automatically takes care of deleting
600 /// a reverse edge internally (so there's no need to swap the parameters).
601 ///
602 void deleteEdge(NodeT *From, NodeT *To) {
603 assert(From)((void)0);
604 assert(To)((void)0);
605 assert(From->getParent() == Parent)((void)0);
606 assert(To->getParent() == Parent)((void)0);
607 DomTreeBuilder::DeleteEdge(*this, From, To);
608 }
609
610 /// Add a new node to the dominator tree information.
611 ///
612 /// This creates a new node as a child of DomBB dominator node, linking it
613 /// into the children list of the immediate dominator.
614 ///
615 /// \param BB New node in CFG.
616 /// \param DomBB CFG node that is dominator for BB.
617 /// \returns New dominator tree node that represents new CFG node.
618 ///
619 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
620 assert(getNode(BB) == nullptr && "Block already in dominator tree!")((void)0);
621 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
622 assert(IDomNode && "Not immediate dominator specified for block!")((void)0);
623 DFSInfoValid = false;
624 return createChild(BB, IDomNode);
625 }
626
627 /// Add a new node to the forward dominator tree and make it a new root.
628 ///
629 /// \param BB New node in CFG.
630 /// \returns New dominator tree node that represents new CFG node.
631 ///
632 DomTreeNodeBase<NodeT> *setNewRoot(NodeT *BB) {
633 assert(getNode(BB) == nullptr && "Block already in dominator tree!")((void)0);
634 assert(!this->isPostDominator() &&((void)0)
635 "Cannot change root of post-dominator tree")((void)0);
636 DFSInfoValid = false;
637 DomTreeNodeBase<NodeT> *NewNode = createNode(BB);
638 if (Roots.empty()) {
639 addRoot(BB);
640 } else {
641 assert(Roots.size() == 1)((void)0);
642 NodeT *OldRoot = Roots.front();
643 auto &OldNode = DomTreeNodes[OldRoot];
644 OldNode = NewNode->addChild(std::move(DomTreeNodes[OldRoot]));
645 OldNode->IDom = NewNode;
646 OldNode->UpdateLevel();
647 Roots[0] = BB;
648 }
649 return RootNode = NewNode;
650 }
651
652 /// changeImmediateDominator - This method is used to update the dominator
653 /// tree information when a node's immediate dominator changes.
654 ///
655 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
656 DomTreeNodeBase<NodeT> *NewIDom) {
657 assert(N && NewIDom && "Cannot change null node pointers!")((void)0);
658 DFSInfoValid = false;
659 N->setIDom(NewIDom);
660 }
661
662 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
663 changeImmediateDominator(getNode(BB), getNode(NewBB));
664 }
665
666 /// eraseNode - Removes a node from the dominator tree. Block must not
667 /// dominate any other blocks. Removes node from its immediate dominator's
668 /// children list. Deletes dominator node associated with basic block BB.
669 void eraseNode(NodeT *BB) {
670 DomTreeNodeBase<NodeT> *Node = getNode(BB);
671 assert(Node && "Removing node that isn't in dominator tree.")((void)0);
672 assert(Node->isLeaf() && "Node is not a leaf node.")((void)0);
673
674 DFSInfoValid = false;
675
676 // Remove node from immediate dominator's children list.
677 DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
678 if (IDom) {
679 const auto I = find(IDom->Children, Node);
680 assert(I != IDom->Children.end() &&((void)0)
681 "Not in immediate dominator children set!")((void)0);
682 // I am no longer your child...
683 IDom->Children.erase(I);
684 }
685
686 DomTreeNodes.erase(BB);
687
688 if (!IsPostDom) return;
689
690 // Remember to update PostDominatorTree roots.
691 auto RIt = llvm::find(Roots, BB);
692 if (RIt != Roots.end()) {
693 std::swap(*RIt, Roots.back());
694 Roots.pop_back();
695 }
696 }
697
698 /// splitBlock - BB is split and now it has one successor. Update dominator
699 /// tree to reflect this change.
700 void splitBlock(NodeT *NewBB) {
701 if (IsPostDominator)
702 Split<Inverse<NodeT *>>(NewBB);
703 else
704 Split<NodeT *>(NewBB);
705 }
706
707 /// print - Convert to human readable form
708 ///
709 void print(raw_ostream &O) const {
710 O << "=============================--------------------------------\n";
711 if (IsPostDominator)
712 O << "Inorder PostDominator Tree: ";
713 else
714 O << "Inorder Dominator Tree: ";
715 if (!DFSInfoValid)
716 O << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
717 O << "\n";
718
719 // The postdom tree can have a null root if there are no returns.
720 if (getRootNode()) PrintDomTree<NodeT>(getRootNode(), O, 1);
721 O << "Roots: ";
722 for (const NodePtr Block : Roots) {
723 Block->printAsOperand(O, false);
724 O << " ";
725 }
726 O << "\n";
727 }
728
729public:
730 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
731 /// dominator tree in dfs order.
732 void updateDFSNumbers() const {
733 if (DFSInfoValid) {
734 SlowQueries = 0;
735 return;
736 }
737
738 SmallVector<std::pair<const DomTreeNodeBase<NodeT> *,
739 typename DomTreeNodeBase<NodeT>::const_iterator>,
740 32> WorkStack;
741
742 const DomTreeNodeBase<NodeT> *ThisRoot = getRootNode();
743 assert((!Parent || ThisRoot) && "Empty constructed DomTree")((void)0);
744 if (!ThisRoot)
745 return;
746
747 // Both dominators and postdominators have a single root node. In the case
748 // case of PostDominatorTree, this node is a virtual root.
749 WorkStack.push_back({ThisRoot, ThisRoot->begin()});
750
751 unsigned DFSNum = 0;
752 ThisRoot->DFSNumIn = DFSNum++;
753
754 while (!WorkStack.empty()) {
755 const DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
756 const auto ChildIt = WorkStack.back().second;
757
758 // If we visited all of the children of this node, "recurse" back up the
759 // stack setting the DFOutNum.
760 if (ChildIt == Node->end()) {
761 Node->DFSNumOut = DFSNum++;
762 WorkStack.pop_back();
763 } else {
764 // Otherwise, recursively visit this child.
765 const DomTreeNodeBase<NodeT> *Child = *ChildIt;
766 ++WorkStack.back().second;
767
768 WorkStack.push_back({Child, Child->begin()});
769 Child->DFSNumIn = DFSNum++;
770 }
771 }
772
773 SlowQueries = 0;
774 DFSInfoValid = true;
775 }
776
777 /// recalculate - compute a dominator tree for the given function
778 void recalculate(ParentType &Func) {
779 Parent = &Func;
780 DomTreeBuilder::Calculate(*this);
781 }
782
783 void recalculate(ParentType &Func, ArrayRef<UpdateType> Updates) {
784 Parent = &Func;
785 DomTreeBuilder::CalculateWithUpdates(*this, Updates);
786 }
787
788 /// verify - checks if the tree is correct. There are 3 level of verification:
789 /// - Full -- verifies if the tree is correct by making sure all the
790 /// properties (including the parent and the sibling property)
791 /// hold.
792 /// Takes O(N^3) time.
793 ///
794 /// - Basic -- checks if the tree is correct, but compares it to a freshly
795 /// constructed tree instead of checking the sibling property.
796 /// Takes O(N^2) time.
797 ///
798 /// - Fast -- checks basic tree structure and compares it with a freshly
799 /// constructed tree.
800 /// Takes O(N^2) time worst case, but is faster in practise (same
801 /// as tree construction).
802 bool verify(VerificationLevel VL = VerificationLevel::Full) const {
803 return DomTreeBuilder::Verify(*this, VL);
804 }
805
806 void reset() {
807 DomTreeNodes.clear();
808 Roots.clear();
809 RootNode = nullptr;
810 Parent = nullptr;
811 DFSInfoValid = false;
812 SlowQueries = 0;
813 }
814
815protected:
816 void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
817
818 DomTreeNodeBase<NodeT> *createChild(NodeT *BB, DomTreeNodeBase<NodeT> *IDom) {
819 return (DomTreeNodes[BB] = IDom->addChild(
820 std::make_unique<DomTreeNodeBase<NodeT>>(BB, IDom)))
821 .get();
822 }
823
824 DomTreeNodeBase<NodeT> *createNode(NodeT *BB) {
825 return (DomTreeNodes[BB] =
826 std::make_unique<DomTreeNodeBase<NodeT>>(BB, nullptr))
827 .get();
828 }
829
830 // NewBB is split and now it has one successor. Update dominator tree to
831 // reflect this change.
832 template <class N>
833 void Split(typename GraphTraits<N>::NodeRef NewBB) {
834 using GraphT = GraphTraits<N>;
835 using NodeRef = typename GraphT::NodeRef;
836 assert(std::distance(GraphT::child_begin(NewBB),((void)0)
837 GraphT::child_end(NewBB)) == 1 &&((void)0)
838 "NewBB should have a single successor!")((void)0);
839 NodeRef NewBBSucc = *GraphT::child_begin(NewBB);
840
841 SmallVector<NodeRef, 4> PredBlocks(children<Inverse<N>>(NewBB));
842
843 assert(!PredBlocks.empty() && "No predblocks?")((void)0);
844
845 bool NewBBDominatesNewBBSucc = true;
846 for (auto Pred : children<Inverse<N>>(NewBBSucc)) {
847 if (Pred != NewBB && !dominates(NewBBSucc, Pred) &&
848 isReachableFromEntry(Pred)) {
849 NewBBDominatesNewBBSucc = false;
850 break;
851 }
852 }
853
854 // Find NewBB's immediate dominator and create new dominator tree node for
855 // NewBB.
856 NodeT *NewBBIDom = nullptr;
857 unsigned i = 0;
858 for (i = 0; i < PredBlocks.size(); ++i)
859 if (isReachableFromEntry(PredBlocks[i])) {
860 NewBBIDom = PredBlocks[i];
861 break;
862 }
863
864 // It's possible that none of the predecessors of NewBB are reachable;
865 // in that case, NewBB itself is unreachable, so nothing needs to be
866 // changed.
867 if (!NewBBIDom) return;
868
869 for (i = i + 1; i < PredBlocks.size(); ++i) {
870 if (isReachableFromEntry(PredBlocks[i]))
871 NewBBIDom = findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
872 }
873
874 // Create the new dominator tree node... and set the idom of NewBB.
875 DomTreeNodeBase<NodeT> *NewBBNode = addNewBlock(NewBB, NewBBIDom);
876
877 // If NewBB strictly dominates other blocks, then it is now the immediate
878 // dominator of NewBBSucc. Update the dominator tree as appropriate.
879 if (NewBBDominatesNewBBSucc) {
880 DomTreeNodeBase<NodeT> *NewBBSuccNode = getNode(NewBBSucc);
881 changeImmediateDominator(NewBBSuccNode, NewBBNode);
882 }
883 }
884
885 private:
886 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
887 const DomTreeNodeBase<NodeT> *B) const {
888 assert(A != B)((void)0);
889 assert(isReachableFromEntry(B))((void)0);
890 assert(isReachableFromEntry(A))((void)0);
891
892 const unsigned ALevel = A->getLevel();
893 const DomTreeNodeBase<NodeT> *IDom;
894
895 // Don't walk nodes above A's subtree. When we reach A's level, we must
896 // either find A or be in some other subtree not dominated by A.
897 while ((IDom = B->getIDom()) != nullptr && IDom->getLevel() >= ALevel)
898 B = IDom; // Walk up the tree
899
900 return B == A;
901 }
902
903 /// Wipe this tree's state without releasing any resources.
904 ///
905 /// This is essentially a post-move helper only. It leaves the object in an
906 /// assignable and destroyable state, but otherwise invalid.
907 void wipe() {
908 DomTreeNodes.clear();
909 RootNode = nullptr;
910 Parent = nullptr;
911 }
912};
913
914template <typename T>
915using DomTreeBase = DominatorTreeBase<T, false>;
916
917template <typename T>
918using PostDomTreeBase = DominatorTreeBase<T, true>;
919
920// These two functions are declared out of line as a workaround for building
921// with old (< r147295) versions of clang because of pr11642.
922template <typename NodeT, bool IsPostDom>
923bool DominatorTreeBase<NodeT, IsPostDom>::dominates(const NodeT *A,
924 const NodeT *B) const {
925 if (A == B)
926 return true;
927
928 // Cast away the const qualifiers here. This is ok since
929 // this function doesn't actually return the values returned
930 // from getNode.
931 return dominates(getNode(const_cast<NodeT *>(A)),
932 getNode(const_cast<NodeT *>(B)));
933}
934template <typename NodeT, bool IsPostDom>
935bool DominatorTreeBase<NodeT, IsPostDom>::properlyDominates(
936 const NodeT *A, const NodeT *B) const {
937 if (A == B)
938 return false;
939
940 // Cast away the const qualifiers here. This is ok since
941 // this function doesn't actually return the values returned
942 // from getNode.
943 return dominates(getNode(const_cast<NodeT *>(A)),
944 getNode(const_cast<NodeT *>(B)));
945}
946
947} // end namespace llvm
948
949#endif // LLVM_SUPPORT_GENERICDOMTREE_H

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT/DenseMap.h

1//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- C++ -*-===//
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 file defines the DenseMap class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_ADT_DENSEMAP_H
14#define LLVM_ADT_DENSEMAP_H
15
16#include "llvm/ADT/DenseMapInfo.h"
17#include "llvm/ADT/EpochTracker.h"
18#include "llvm/Support/AlignOf.h"
19#include "llvm/Support/Compiler.h"
20#include "llvm/Support/MathExtras.h"
21#include "llvm/Support/MemAlloc.h"
22#include "llvm/Support/ReverseIteration.h"
23#include "llvm/Support/type_traits.h"
24#include <algorithm>
25#include <cassert>
26#include <cstddef>
27#include <cstring>
28#include <initializer_list>
29#include <iterator>
30#include <new>
31#include <type_traits>
32#include <utility>
33
34namespace llvm {
35
36namespace detail {
37
38// We extend a pair to allow users to override the bucket type with their own
39// implementation without requiring two members.
40template <typename KeyT, typename ValueT>
41struct DenseMapPair : public std::pair<KeyT, ValueT> {
42 using std::pair<KeyT, ValueT>::pair;
43
44 KeyT &getFirst() { return std::pair<KeyT, ValueT>::first; }
45 const KeyT &getFirst() const { return std::pair<KeyT, ValueT>::first; }
46 ValueT &getSecond() { return std::pair<KeyT, ValueT>::second; }
47 const ValueT &getSecond() const { return std::pair<KeyT, ValueT>::second; }
48};
49
50} // end namespace detail
51
52template <typename KeyT, typename ValueT,
53 typename KeyInfoT = DenseMapInfo<KeyT>,
54 typename Bucket = llvm::detail::DenseMapPair<KeyT, ValueT>,
55 bool IsConst = false>
56class DenseMapIterator;
57
58template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
59 typename BucketT>
60class DenseMapBase : public DebugEpochBase {
61 template <typename T>
62 using const_arg_type_t = typename const_pointer_or_const_ref<T>::type;
63
64public:
65 using size_type = unsigned;
66 using key_type = KeyT;
67 using mapped_type = ValueT;
68 using value_type = BucketT;
69
70 using iterator = DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT>;
71 using const_iterator =
72 DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT, true>;
73
74 inline iterator begin() {
75 // When the map is empty, avoid the overhead of advancing/retreating past
76 // empty buckets.
77 if (empty())
78 return end();
79 if (shouldReverseIterate<KeyT>())
80 return makeIterator(getBucketsEnd() - 1, getBuckets(), *this);
81 return makeIterator(getBuckets(), getBucketsEnd(), *this);
82 }
83 inline iterator end() {
84 return makeIterator(getBucketsEnd(), getBucketsEnd(), *this, true);
85 }
86 inline const_iterator begin() const {
87 if (empty())
88 return end();
89 if (shouldReverseIterate<KeyT>())
90 return makeConstIterator(getBucketsEnd() - 1, getBuckets(), *this);
91 return makeConstIterator(getBuckets(), getBucketsEnd(), *this);
92 }
93 inline const_iterator end() const {
94 return makeConstIterator(getBucketsEnd(), getBucketsEnd(), *this, true);
95 }
96
97 LLVM_NODISCARD[[clang::warn_unused_result]] bool empty() const {
98 return getNumEntries() == 0;
99 }
100 unsigned size() const { return getNumEntries(); }
101
102 /// Grow the densemap so that it can contain at least \p NumEntries items
103 /// before resizing again.
104 void reserve(size_type NumEntries) {
105 auto NumBuckets = getMinBucketToReserveForEntries(NumEntries);
106 incrementEpoch();
107 if (NumBuckets > getNumBuckets())
108 grow(NumBuckets);
109 }
110
111 void clear() {
112 incrementEpoch();
113 if (getNumEntries() == 0 && getNumTombstones() == 0) return;
114
115 // If the capacity of the array is huge, and the # elements used is small,
116 // shrink the array.
117 if (getNumEntries() * 4 < getNumBuckets() && getNumBuckets() > 64) {
118 shrink_and_clear();
119 return;
120 }
121
122 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
123 if (std::is_trivially_destructible<ValueT>::value) {
124 // Use a simpler loop when values don't need destruction.
125 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P)
126 P->getFirst() = EmptyKey;
127 } else {
128 unsigned NumEntries = getNumEntries();
129 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
130 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey)) {
131 if (!KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
132 P->getSecond().~ValueT();
133 --NumEntries;
134 }
135 P->getFirst() = EmptyKey;
136 }
137 }
138 assert(NumEntries == 0 && "Node count imbalance!")((void)0);
139 }
140 setNumEntries(0);
141 setNumTombstones(0);
142 }
143
144 /// Return 1 if the specified key is in the map, 0 otherwise.
145 size_type count(const_arg_type_t<KeyT> Val) const {
146 const BucketT *TheBucket;
147 return LookupBucketFor(Val, TheBucket) ? 1 : 0;
148 }
149
150 iterator find(const_arg_type_t<KeyT> Val) {
151 BucketT *TheBucket;
152 if (LookupBucketFor(Val, TheBucket))
153 return makeIterator(TheBucket,
154 shouldReverseIterate<KeyT>() ? getBuckets()
155 : getBucketsEnd(),
156 *this, true);
157 return end();
158 }
159 const_iterator find(const_arg_type_t<KeyT> Val) const {
160 const BucketT *TheBucket;
161 if (LookupBucketFor(Val, TheBucket))
162 return makeConstIterator(TheBucket,
163 shouldReverseIterate<KeyT>() ? getBuckets()
164 : getBucketsEnd(),
165 *this, true);
166 return end();
167 }
168
169 /// Alternate version of find() which allows a different, and possibly
170 /// less expensive, key type.
171 /// The DenseMapInfo is responsible for supplying methods
172 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
173 /// type used.
174 template<class LookupKeyT>
175 iterator find_as(const LookupKeyT &Val) {
176 BucketT *TheBucket;
177 if (LookupBucketFor(Val, TheBucket))
178 return makeIterator(TheBucket,
179 shouldReverseIterate<KeyT>() ? getBuckets()
180 : getBucketsEnd(),
181 *this, true);
182 return end();
183 }
184 template<class LookupKeyT>
185 const_iterator find_as(const LookupKeyT &Val) const {
186 const BucketT *TheBucket;
187 if (LookupBucketFor(Val, TheBucket))
188 return makeConstIterator(TheBucket,
189 shouldReverseIterate<KeyT>() ? getBuckets()
190 : getBucketsEnd(),
191 *this, true);
192 return end();
193 }
194
195 /// lookup - Return the entry for the specified key, or a default
196 /// constructed value if no such entry exists.
197 ValueT lookup(const_arg_type_t<KeyT> Val) const {
198 const BucketT *TheBucket;
199 if (LookupBucketFor(Val, TheBucket))
200 return TheBucket->getSecond();
201 return ValueT();
202 }
203
204 // Inserts key,value pair into the map if the key isn't already in the map.
205 // If the key is already in the map, it returns false and doesn't update the
206 // value.
207 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
208 return try_emplace(KV.first, KV.second);
209 }
210
211 // Inserts key,value pair into the map if the key isn't already in the map.
212 // If the key is already in the map, it returns false and doesn't update the
213 // value.
214 std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
215 return try_emplace(std::move(KV.first), std::move(KV.second));
216 }
217
218 // Inserts key,value pair into the map if the key isn't already in the map.
219 // The value is constructed in-place if the key is not in the map, otherwise
220 // it is not moved.
221 template <typename... Ts>
222 std::pair<iterator, bool> try_emplace(KeyT &&Key, Ts &&... Args) {
223 BucketT *TheBucket;
224 if (LookupBucketFor(Key, TheBucket))
225 return std::make_pair(makeIterator(TheBucket,
226 shouldReverseIterate<KeyT>()
227 ? getBuckets()
228 : getBucketsEnd(),
229 *this, true),
230 false); // Already in map.
231
232 // Otherwise, insert the new element.
233 TheBucket =
234 InsertIntoBucket(TheBucket, std::move(Key), std::forward<Ts>(Args)...);
235 return std::make_pair(makeIterator(TheBucket,
236 shouldReverseIterate<KeyT>()
237 ? getBuckets()
238 : getBucketsEnd(),
239 *this, true),
240 true);
241 }
242
243 // Inserts key,value pair into the map if the key isn't already in the map.
244 // The value is constructed in-place if the key is not in the map, otherwise
245 // it is not moved.
246 template <typename... Ts>
247 std::pair<iterator, bool> try_emplace(const KeyT &Key, Ts &&... Args) {
248 BucketT *TheBucket;
249 if (LookupBucketFor(Key, TheBucket))
250 return std::make_pair(makeIterator(TheBucket,
251 shouldReverseIterate<KeyT>()
252 ? getBuckets()
253 : getBucketsEnd(),
254 *this, true),
255 false); // Already in map.
256
257 // Otherwise, insert the new element.
258 TheBucket = InsertIntoBucket(TheBucket, Key, std::forward<Ts>(Args)...);
259 return std::make_pair(makeIterator(TheBucket,
260 shouldReverseIterate<KeyT>()
261 ? getBuckets()
262 : getBucketsEnd(),
263 *this, true),
264 true);
265 }
266
267 /// Alternate version of insert() which allows a different, and possibly
268 /// less expensive, key type.
269 /// The DenseMapInfo is responsible for supplying methods
270 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
271 /// type used.
272 template <typename LookupKeyT>
273 std::pair<iterator, bool> insert_as(std::pair<KeyT, ValueT> &&KV,
274 const LookupKeyT &Val) {
275 BucketT *TheBucket;
276 if (LookupBucketFor(Val, TheBucket))
277 return std::make_pair(makeIterator(TheBucket,
278 shouldReverseIterate<KeyT>()
279 ? getBuckets()
280 : getBucketsEnd(),
281 *this, true),
282 false); // Already in map.
283
284 // Otherwise, insert the new element.
285 TheBucket = InsertIntoBucketWithLookup(TheBucket, std::move(KV.first),
286 std::move(KV.second), Val);
287 return std::make_pair(makeIterator(TheBucket,
288 shouldReverseIterate<KeyT>()
289 ? getBuckets()
290 : getBucketsEnd(),
291 *this, true),
292 true);
293 }
294
295 /// insert - Range insertion of pairs.
296 template<typename InputIt>
297 void insert(InputIt I, InputIt E) {
298 for (; I != E; ++I)
299 insert(*I);
300 }
301
302 bool erase(const KeyT &Val) {
303 BucketT *TheBucket;
304 if (!LookupBucketFor(Val, TheBucket))
305 return false; // not in map.
306
307 TheBucket->getSecond().~ValueT();
308 TheBucket->getFirst() = getTombstoneKey();
309 decrementNumEntries();
310 incrementNumTombstones();
311 return true;
312 }
313 void erase(iterator I) {
314 BucketT *TheBucket = &*I;
315 TheBucket->getSecond().~ValueT();
316 TheBucket->getFirst() = getTombstoneKey();
317 decrementNumEntries();
318 incrementNumTombstones();
319 }
320
321 value_type& FindAndConstruct(const KeyT &Key) {
322 BucketT *TheBucket;
323 if (LookupBucketFor(Key, TheBucket))
324 return *TheBucket;
325
326 return *InsertIntoBucket(TheBucket, Key);
327 }
328
329 ValueT &operator[](const KeyT &Key) {
330 return FindAndConstruct(Key).second;
331 }
332
333 value_type& FindAndConstruct(KeyT &&Key) {
334 BucketT *TheBucket;
335 if (LookupBucketFor(Key, TheBucket))
336 return *TheBucket;
337
338 return *InsertIntoBucket(TheBucket, std::move(Key));
339 }
340
341 ValueT &operator[](KeyT &&Key) {
342 return FindAndConstruct(std::move(Key)).second;
343 }
344
345 /// isPointerIntoBucketsArray - Return true if the specified pointer points
346 /// somewhere into the DenseMap's array of buckets (i.e. either to a key or
347 /// value in the DenseMap).
348 bool isPointerIntoBucketsArray(const void *Ptr) const {
349 return Ptr >= getBuckets() && Ptr < getBucketsEnd();
350 }
351
352 /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
353 /// array. In conjunction with the previous method, this can be used to
354 /// determine whether an insertion caused the DenseMap to reallocate.
355 const void *getPointerIntoBucketsArray() const { return getBuckets(); }
356
357protected:
358 DenseMapBase() = default;
359
360 void destroyAll() {
361 if (getNumBuckets() == 0) // Nothing to do.
362 return;
363
364 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
365 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
366 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
367 !KeyInfoT::isEqual(P->getFirst(), TombstoneKey))
368 P->getSecond().~ValueT();
369 P->getFirst().~KeyT();
370 }
371 }
372
373 void initEmpty() {
374 setNumEntries(0);
375 setNumTombstones(0);
376
377 assert((getNumBuckets() & (getNumBuckets()-1)) == 0 &&((void)0)
378 "# initial buckets must be a power of two!")((void)0);
379 const KeyT EmptyKey = getEmptyKey();
380 for (BucketT *B = getBuckets(), *E = getBucketsEnd(); B != E; ++B)
381 ::new (&B->getFirst()) KeyT(EmptyKey);
382 }
383
384 /// Returns the number of buckets to allocate to ensure that the DenseMap can
385 /// accommodate \p NumEntries without need to grow().
386 unsigned getMinBucketToReserveForEntries(unsigned NumEntries) {
387 // Ensure that "NumEntries * 4 < NumBuckets * 3"
388 if (NumEntries == 0)
389 return 0;
390 // +1 is required because of the strict equality.
391 // For example if NumEntries is 48, we need to return 401.
392 return NextPowerOf2(NumEntries * 4 / 3 + 1);
393 }
394
395 void moveFromOldBuckets(BucketT *OldBucketsBegin, BucketT *OldBucketsEnd) {
396 initEmpty();
397
398 // Insert all the old elements.
399 const KeyT EmptyKey = getEmptyKey();
400 const KeyT TombstoneKey = getTombstoneKey();
401 for (BucketT *B = OldBucketsBegin, *E = OldBucketsEnd; B != E; ++B) {
402 if (!KeyInfoT::isEqual(B->getFirst(), EmptyKey) &&
403 !KeyInfoT::isEqual(B->getFirst(), TombstoneKey)) {
404 // Insert the key/value into the new table.
405 BucketT *DestBucket;
406 bool FoundVal = LookupBucketFor(B->getFirst(), DestBucket);
407 (void)FoundVal; // silence warning.
408 assert(!FoundVal && "Key already in new map?")((void)0);
409 DestBucket->getFirst() = std::move(B->getFirst());
410 ::new (&DestBucket->getSecond()) ValueT(std::move(B->getSecond()));
411 incrementNumEntries();
412
413 // Free the value.
414 B->getSecond().~ValueT();
415 }
416 B->getFirst().~KeyT();
417 }
418 }
419
420 template <typename OtherBaseT>
421 void copyFrom(
422 const DenseMapBase<OtherBaseT, KeyT, ValueT, KeyInfoT, BucketT> &other) {
423 assert(&other != this)((void)0);
424 assert(getNumBuckets() == other.getNumBuckets())((void)0);
425
426 setNumEntries(other.getNumEntries());
427 setNumTombstones(other.getNumTombstones());
428
429 if (std::is_trivially_copyable<KeyT>::value &&
430 std::is_trivially_copyable<ValueT>::value)
431 memcpy(reinterpret_cast<void *>(getBuckets()), other.getBuckets(),
432 getNumBuckets() * sizeof(BucketT));
433 else
434 for (size_t i = 0; i < getNumBuckets(); ++i) {
435 ::new (&getBuckets()[i].getFirst())
436 KeyT(other.getBuckets()[i].getFirst());
437 if (!KeyInfoT::isEqual(getBuckets()[i].getFirst(), getEmptyKey()) &&
438 !KeyInfoT::isEqual(getBuckets()[i].getFirst(), getTombstoneKey()))
439 ::new (&getBuckets()[i].getSecond())
440 ValueT(other.getBuckets()[i].getSecond());
441 }
442 }
443
444 static unsigned getHashValue(const KeyT &Val) {
445 return KeyInfoT::getHashValue(Val);
446 }
447
448 template<typename LookupKeyT>
449 static unsigned getHashValue(const LookupKeyT &Val) {
450 return KeyInfoT::getHashValue(Val);
451 }
452
453 static const KeyT getEmptyKey() {
454 static_assert(std::is_base_of<DenseMapBase, DerivedT>::value,
455 "Must pass the derived type to this template!");
456 return KeyInfoT::getEmptyKey();
457 }
458
459 static const KeyT getTombstoneKey() {
460 return KeyInfoT::getTombstoneKey();
461 }
462
463private:
464 iterator makeIterator(BucketT *P, BucketT *E,
465 DebugEpochBase &Epoch,
466 bool NoAdvance=false) {
467 if (shouldReverseIterate<KeyT>()) {
468 BucketT *B = P == getBucketsEnd() ? getBuckets() : P + 1;
469 return iterator(B, E, Epoch, NoAdvance);
470 }
471 return iterator(P, E, Epoch, NoAdvance);
472 }
473
474 const_iterator makeConstIterator(const BucketT *P, const BucketT *E,
475 const DebugEpochBase &Epoch,
476 const bool NoAdvance=false) const {
477 if (shouldReverseIterate<KeyT>()) {
478 const BucketT *B = P == getBucketsEnd() ? getBuckets() : P + 1;
479 return const_iterator(B, E, Epoch, NoAdvance);
480 }
481 return const_iterator(P, E, Epoch, NoAdvance);
482 }
483
484 unsigned getNumEntries() const {
485 return static_cast<const DerivedT *>(this)->getNumEntries();
486 }
487
488 void setNumEntries(unsigned Num) {
489 static_cast<DerivedT *>(this)->setNumEntries(Num);
490 }
491
492 void incrementNumEntries() {
493 setNumEntries(getNumEntries() + 1);
494 }
495
496 void decrementNumEntries() {
497 setNumEntries(getNumEntries() - 1);
498 }
499
500 unsigned getNumTombstones() const {
501 return static_cast<const DerivedT *>(this)->getNumTombstones();
502 }
503
504 void setNumTombstones(unsigned Num) {
505 static_cast<DerivedT *>(this)->setNumTombstones(Num);
506 }
507
508 void incrementNumTombstones() {
509 setNumTombstones(getNumTombstones() + 1);
510 }
511
512 void decrementNumTombstones() {
513 setNumTombstones(getNumTombstones() - 1);
514 }
515
516 const BucketT *getBuckets() const {
517 return static_cast<const DerivedT *>(this)->getBuckets();
518 }
519
520 BucketT *getBuckets() {
521 return static_cast<DerivedT *>(this)->getBuckets();
522 }
523
524 unsigned getNumBuckets() const {
525 return static_cast<const DerivedT *>(this)->getNumBuckets();
526 }
527
528 BucketT *getBucketsEnd() {
529 return getBuckets() + getNumBuckets();
530 }
531
532 const BucketT *getBucketsEnd() const {
533 return getBuckets() + getNumBuckets();
534 }
535
536 void grow(unsigned AtLeast) {
537 static_cast<DerivedT *>(this)->grow(AtLeast);
538 }
539
540 void shrink_and_clear() {
541 static_cast<DerivedT *>(this)->shrink_and_clear();
542 }
543
544 template <typename KeyArg, typename... ValueArgs>
545 BucketT *InsertIntoBucket(BucketT *TheBucket, KeyArg &&Key,
546 ValueArgs &&... Values) {
547 TheBucket = InsertIntoBucketImpl(Key, Key, TheBucket);
548
549 TheBucket->getFirst() = std::forward<KeyArg>(Key);
550 ::new (&TheBucket->getSecond()) ValueT(std::forward<ValueArgs>(Values)...);
551 return TheBucket;
552 }
553
554 template <typename LookupKeyT>
555 BucketT *InsertIntoBucketWithLookup(BucketT *TheBucket, KeyT &&Key,
556 ValueT &&Value, LookupKeyT &Lookup) {
557 TheBucket = InsertIntoBucketImpl(Key, Lookup, TheBucket);
558
559 TheBucket->getFirst() = std::move(Key);
560 ::new (&TheBucket->getSecond()) ValueT(std::move(Value));
561 return TheBucket;
562 }
563
564 template <typename LookupKeyT>
565 BucketT *InsertIntoBucketImpl(const KeyT &Key, const LookupKeyT &Lookup,
566 BucketT *TheBucket) {
567 incrementEpoch();
568
569 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
570 // the buckets are empty (meaning that many are filled with tombstones),
571 // grow the table.
572 //
573 // The later case is tricky. For example, if we had one empty bucket with
574 // tons of tombstones, failing lookups (e.g. for insertion) would have to
575 // probe almost the entire table until it found the empty bucket. If the
576 // table completely filled with tombstones, no lookup would ever succeed,
577 // causing infinite loops in lookup.
578 unsigned NewNumEntries = getNumEntries() + 1;
579 unsigned NumBuckets = getNumBuckets();
580 if (LLVM_UNLIKELY(NewNumEntries * 4 >= NumBuckets * 3)__builtin_expect((bool)(NewNumEntries * 4 >= NumBuckets * 3
), false)
) {
581 this->grow(NumBuckets * 2);
582 LookupBucketFor(Lookup, TheBucket);
583 NumBuckets = getNumBuckets();
584 } else if (LLVM_UNLIKELY(NumBuckets-(NewNumEntries+getNumTombstones()) <=__builtin_expect((bool)(NumBuckets-(NewNumEntries+getNumTombstones
()) <= NumBuckets/8), false)
585 NumBuckets/8)__builtin_expect((bool)(NumBuckets-(NewNumEntries+getNumTombstones
()) <= NumBuckets/8), false)
) {
586 this->grow(NumBuckets);
587 LookupBucketFor(Lookup, TheBucket);
588 }
589 assert(TheBucket)((void)0);
590
591 // Only update the state after we've grown our bucket space appropriately
592 // so that when growing buckets we have self-consistent entry count.
593 incrementNumEntries();
594
595 // If we are writing over a tombstone, remember this.
596 const KeyT EmptyKey = getEmptyKey();
597 if (!KeyInfoT::isEqual(TheBucket->getFirst(), EmptyKey))
598 decrementNumTombstones();
599
600 return TheBucket;
601 }
602
603 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
604 /// FoundBucket. If the bucket contains the key and a value, this returns
605 /// true, otherwise it returns a bucket with an empty marker or tombstone and
606 /// returns false.
607 template<typename LookupKeyT>
608 bool LookupBucketFor(const LookupKeyT &Val,
609 const BucketT *&FoundBucket) const {
610 const BucketT *BucketsPtr = getBuckets();
611 const unsigned NumBuckets = getNumBuckets();
612
613 if (NumBuckets == 0) {
614 FoundBucket = nullptr;
615 return false;
616 }
617
618 // FoundTombstone - Keep track of whether we find a tombstone while probing.
619 const BucketT *FoundTombstone = nullptr;
620 const KeyT EmptyKey = getEmptyKey();
621 const KeyT TombstoneKey = getTombstoneKey();
622 assert(!KeyInfoT::isEqual(Val, EmptyKey) &&((void)0)
623 !KeyInfoT::isEqual(Val, TombstoneKey) &&((void)0)
624 "Empty/Tombstone value shouldn't be inserted into map!")((void)0);
625
626 unsigned BucketNo = getHashValue(Val) & (NumBuckets-1);
627 unsigned ProbeAmt = 1;
628 while (true) {
629 const BucketT *ThisBucket = BucketsPtr + BucketNo;
630 // Found Val's bucket? If so, return it.
631 if (LLVM_LIKELY(KeyInfoT::isEqual(Val, ThisBucket->getFirst()))__builtin_expect((bool)(KeyInfoT::isEqual(Val, ThisBucket->
getFirst())), true)
) {
632 FoundBucket = ThisBucket;
633 return true;
634 }
635
636 // If we found an empty bucket, the key doesn't exist in the set.
637 // Insert it and return the default value.
638 if (LLVM_LIKELY(KeyInfoT::isEqual(ThisBucket->getFirst(), EmptyKey))__builtin_expect((bool)(KeyInfoT::isEqual(ThisBucket->getFirst
(), EmptyKey)), true)
) {
639 // If we've already seen a tombstone while probing, fill it in instead
640 // of the empty bucket we eventually probed to.
641 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
642 return false;
643 }
644
645 // If this is a tombstone, remember it. If Val ends up not in the map, we
646 // prefer to return it than something that would require more probing.
647 if (KeyInfoT::isEqual(ThisBucket->getFirst(), TombstoneKey) &&
648 !FoundTombstone)
649 FoundTombstone = ThisBucket; // Remember the first tombstone found.
650
651 // Otherwise, it's a hash collision or a tombstone, continue quadratic
652 // probing.
653 BucketNo += ProbeAmt++;
654 BucketNo &= (NumBuckets-1);
655 }
656 }
657
658 template <typename LookupKeyT>
659 bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) {
660 const BucketT *ConstFoundBucket;
661 bool Result = const_cast<const DenseMapBase *>(this)
662 ->LookupBucketFor(Val, ConstFoundBucket);
663 FoundBucket = const_cast<BucketT *>(ConstFoundBucket);
664 return Result;
665 }
666
667public:
668 /// Return the approximate size (in bytes) of the actual map.
669 /// This is just the raw memory used by DenseMap.
670 /// If entries are pointers to objects, the size of the referenced objects
671 /// are not included.
672 size_t getMemorySize() const {
673 return getNumBuckets() * sizeof(BucketT);
674 }
675};
676
677/// Equality comparison for DenseMap.
678///
679/// Iterates over elements of LHS confirming that each (key, value) pair in LHS
680/// is also in RHS, and that no additional pairs are in RHS.
681/// Equivalent to N calls to RHS.find and N value comparisons. Amortized
682/// complexity is linear, worst case is O(N^2) (if every hash collides).
683template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
684 typename BucketT>
685bool operator==(
686 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &LHS,
687 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &RHS) {
688 if (LHS.size() != RHS.size())
689 return false;
690
691 for (auto &KV : LHS) {
692 auto I = RHS.find(KV.first);
693 if (I == RHS.end() || I->second != KV.second)
694 return false;
695 }
696
697 return true;
698}
699
700/// Inequality comparison for DenseMap.
701///
702/// Equivalent to !(LHS == RHS). See operator== for performance notes.
703template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
704 typename BucketT>
705bool operator!=(
706 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &LHS,
707 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &RHS) {
708 return !(LHS == RHS);
709}
710
711template <typename KeyT, typename ValueT,
712 typename KeyInfoT = DenseMapInfo<KeyT>,
713 typename BucketT = llvm::detail::DenseMapPair<KeyT, ValueT>>
714class DenseMap : public DenseMapBase<DenseMap<KeyT, ValueT, KeyInfoT, BucketT>,
715 KeyT, ValueT, KeyInfoT, BucketT> {
716 friend class DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
717
718 // Lift some types from the dependent base class into this class for
719 // simplicity of referring to them.
720 using BaseT = DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
721
722 BucketT *Buckets;
723 unsigned NumEntries;
724 unsigned NumTombstones;
725 unsigned NumBuckets;
726
727public:
728 /// Create a DenseMap with an optional \p InitialReserve that guarantee that
729 /// this number of elements can be inserted in the map without grow()
730 explicit DenseMap(unsigned InitialReserve = 0) { init(InitialReserve); }
731
732 DenseMap(const DenseMap &other) : BaseT() {
733 init(0);
734 copyFrom(other);
735 }
736
737 DenseMap(DenseMap &&other) : BaseT() {
738 init(0);
739 swap(other);
740 }
741
742 template<typename InputIt>
743 DenseMap(const InputIt &I, const InputIt &E) {
744 init(std::distance(I, E));
745 this->insert(I, E);
746 }
747
748 DenseMap(std::initializer_list<typename BaseT::value_type> Vals) {
749 init(Vals.size());
750 this->insert(Vals.begin(), Vals.end());
751 }
752
753 ~DenseMap() {
754 this->destroyAll();
755 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
756 }
757
758 void swap(DenseMap& RHS) {
759 this->incrementEpoch();
760 RHS.incrementEpoch();
761 std::swap(Buckets, RHS.Buckets);
762 std::swap(NumEntries, RHS.NumEntries);
763 std::swap(NumTombstones, RHS.NumTombstones);
764 std::swap(NumBuckets, RHS.NumBuckets);
765 }
766
767 DenseMap& operator=(const DenseMap& other) {
768 if (&other != this)
769 copyFrom(other);
770 return *this;
771 }
772
773 DenseMap& operator=(DenseMap &&other) {
774 this->destroyAll();
775 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
776 init(0);
777 swap(other);
778 return *this;
779 }
780
781 void copyFrom(const DenseMap& other) {
782 this->destroyAll();
783 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
784 if (allocateBuckets(other.NumBuckets)) {
785 this->BaseT::copyFrom(other);
786 } else {
787 NumEntries = 0;
788 NumTombstones = 0;
789 }
790 }
791
792 void init(unsigned InitNumEntries) {
793 auto InitBuckets = BaseT::getMinBucketToReserveForEntries(InitNumEntries);
794 if (allocateBuckets(InitBuckets)) {
795 this->BaseT::initEmpty();
796 } else {
797 NumEntries = 0;
798 NumTombstones = 0;
799 }
800 }
801
802 void grow(unsigned AtLeast) {
803 unsigned OldNumBuckets = NumBuckets;
804 BucketT *OldBuckets = Buckets;
805
806 allocateBuckets(std::max<unsigned>(64, static_cast<unsigned>(NextPowerOf2(AtLeast-1))));
807 assert(Buckets)((void)0);
808 if (!OldBuckets) {
809 this->BaseT::initEmpty();
810 return;
811 }
812
813 this->moveFromOldBuckets(OldBuckets, OldBuckets+OldNumBuckets);
814
815 // Free the old table.
816 deallocate_buffer(OldBuckets, sizeof(BucketT) * OldNumBuckets,
817 alignof(BucketT));
818 }
819
820 void shrink_and_clear() {
821 unsigned OldNumBuckets = NumBuckets;
822 unsigned OldNumEntries = NumEntries;
823 this->destroyAll();
824
825 // Reduce the number of buckets.
826 unsigned NewNumBuckets = 0;
827 if (OldNumEntries)
828 NewNumBuckets = std::max(64, 1 << (Log2_32_Ceil(OldNumEntries) + 1));
829 if (NewNumBuckets == NumBuckets) {
830 this->BaseT::initEmpty();
831 return;
832 }
833
834 deallocate_buffer(Buckets, sizeof(BucketT) * OldNumBuckets,
835 alignof(BucketT));
836 init(NewNumBuckets);
837 }
838
839private:
840 unsigned getNumEntries() const {
841 return NumEntries;
842 }
843
844 void setNumEntries(unsigned Num) {
845 NumEntries = Num;
846 }
847
848 unsigned getNumTombstones() const {
849 return NumTombstones;
850 }
851
852 void setNumTombstones(unsigned Num) {
853 NumTombstones = Num;
854 }
855
856 BucketT *getBuckets() const {
857 return Buckets;
858 }
859
860 unsigned getNumBuckets() const {
861 return NumBuckets;
862 }
863
864 bool allocateBuckets(unsigned Num) {
865 NumBuckets = Num;
866 if (NumBuckets == 0) {
867 Buckets = nullptr;
868 return false;
869 }
870
871 Buckets = static_cast<BucketT *>(
872 allocate_buffer(sizeof(BucketT) * NumBuckets, alignof(BucketT)));
873 return true;
874 }
875};
876
877template <typename KeyT, typename ValueT, unsigned InlineBuckets = 4,
878 typename KeyInfoT = DenseMapInfo<KeyT>,
879 typename BucketT = llvm::detail::DenseMapPair<KeyT, ValueT>>
880class SmallDenseMap
881 : public DenseMapBase<
882 SmallDenseMap<KeyT, ValueT, InlineBuckets, KeyInfoT, BucketT>, KeyT,
883 ValueT, KeyInfoT, BucketT> {
884 friend class DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
885
886 // Lift some types from the dependent base class into this class for
887 // simplicity of referring to them.
888 using BaseT = DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
889
890 static_assert(isPowerOf2_64(InlineBuckets),
891 "InlineBuckets must be a power of 2.");
892
893 unsigned Small : 1;
894 unsigned NumEntries : 31;
895 unsigned NumTombstones;
896
897 struct LargeRep {
898 BucketT *Buckets;
899 unsigned NumBuckets;
900 };
901
902 /// A "union" of an inline bucket array and the struct representing
903 /// a large bucket. This union will be discriminated by the 'Small' bit.
904 AlignedCharArrayUnion<BucketT[InlineBuckets], LargeRep> storage;
905
906public:
907 explicit SmallDenseMap(unsigned NumInitBuckets = 0) {
908 init(NumInitBuckets);
909 }
910
911 SmallDenseMap(const SmallDenseMap &other) : BaseT() {
912 init(0);
913 copyFrom(other);
914 }
915
916 SmallDenseMap(SmallDenseMap &&other) : BaseT() {
917 init(0);
918 swap(other);
919 }
920
921 template<typename InputIt>
922 SmallDenseMap(const InputIt &I, const InputIt &E) {
923 init(NextPowerOf2(std::distance(I, E)));
924 this->insert(I, E);
925 }
926
927 SmallDenseMap(std::initializer_list<typename BaseT::value_type> Vals)
928 : SmallDenseMap(Vals.begin(), Vals.end()) {}
929
930 ~SmallDenseMap() {
931 this->destroyAll();
932 deallocateBuckets();
933 }
934
935 void swap(SmallDenseMap& RHS) {
936 unsigned TmpNumEntries = RHS.NumEntries;
937 RHS.NumEntries = NumEntries;
938 NumEntries = TmpNumEntries;
939 std::swap(NumTombstones, RHS.NumTombstones);
940
941 const KeyT EmptyKey = this->getEmptyKey();
942 const KeyT TombstoneKey = this->getTombstoneKey();
943 if (Small && RHS.Small) {
944 // If we're swapping inline bucket arrays, we have to cope with some of
945 // the tricky bits of DenseMap's storage system: the buckets are not
946 // fully initialized. Thus we swap every key, but we may have
947 // a one-directional move of the value.
948 for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
949 BucketT *LHSB = &getInlineBuckets()[i],
950 *RHSB = &RHS.getInlineBuckets()[i];
951 bool hasLHSValue = (!KeyInfoT::isEqual(LHSB->getFirst(), EmptyKey) &&
952 !KeyInfoT::isEqual(LHSB->getFirst(), TombstoneKey));
953 bool hasRHSValue = (!KeyInfoT::isEqual(RHSB->getFirst(), EmptyKey) &&
954 !KeyInfoT::isEqual(RHSB->getFirst(), TombstoneKey));
955 if (hasLHSValue && hasRHSValue) {
956 // Swap together if we can...
957 std::swap(*LHSB, *RHSB);
958 continue;
959 }
960 // Swap separately and handle any asymmetry.
961 std::swap(LHSB->getFirst(), RHSB->getFirst());
962 if (hasLHSValue) {
963 ::new (&RHSB->getSecond()) ValueT(std::move(LHSB->getSecond()));
964 LHSB->getSecond().~ValueT();
965 } else if (hasRHSValue) {
966 ::new (&LHSB->getSecond()) ValueT(std::move(RHSB->getSecond()));
967 RHSB->getSecond().~ValueT();
968 }
969 }
970 return;
971 }
972 if (!Small && !RHS.Small) {
973 std::swap(getLargeRep()->Buckets, RHS.getLargeRep()->Buckets);
974 std::swap(getLargeRep()->NumBuckets, RHS.getLargeRep()->NumBuckets);
975 return;
976 }
977
978 SmallDenseMap &SmallSide = Small ? *this : RHS;
979 SmallDenseMap &LargeSide = Small ? RHS : *this;
980
981 // First stash the large side's rep and move the small side across.
982 LargeRep TmpRep = std::move(*LargeSide.getLargeRep());
983 LargeSide.getLargeRep()->~LargeRep();
984 LargeSide.Small = true;
985 // This is similar to the standard move-from-old-buckets, but the bucket
986 // count hasn't actually rotated in this case. So we have to carefully
987 // move construct the keys and values into their new locations, but there
988 // is no need to re-hash things.
989 for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
990 BucketT *NewB = &LargeSide.getInlineBuckets()[i],
991 *OldB = &SmallSide.getInlineBuckets()[i];
992 ::new (&NewB->getFirst()) KeyT(std::move(OldB->getFirst()));
993 OldB->getFirst().~KeyT();
994 if (!KeyInfoT::isEqual(NewB->getFirst(), EmptyKey) &&
995 !KeyInfoT::isEqual(NewB->getFirst(), TombstoneKey)) {
996 ::new (&NewB->getSecond()) ValueT(std::move(OldB->getSecond()));
997 OldB->getSecond().~ValueT();
998 }
999 }
1000
1001 // The hard part of moving the small buckets across is done, just move
1002 // the TmpRep into its new home.
1003 SmallSide.Small = false;
1004 new (SmallSide.getLargeRep()) LargeRep(std::move(TmpRep));
1005 }
1006
1007 SmallDenseMap& operator=(const SmallDenseMap& other) {
1008 if (&other != this)
1009 copyFrom(other);
1010 return *this;
1011 }
1012
1013 SmallDenseMap& operator=(SmallDenseMap &&other) {
1014 this->destroyAll();
1015 deallocateBuckets();
1016 init(0);
1017 swap(other);
1018 return *this;
1019 }
1020
1021 void copyFrom(const SmallDenseMap& other) {
1022 this->destroyAll();
1023 deallocateBuckets();
1024 Small = true;
1025 if (other.getNumBuckets() > InlineBuckets) {
1026 Small = false;
1027 new (getLargeRep()) LargeRep(allocateBuckets(other.getNumBuckets()));
1028 }
1029 this->BaseT::copyFrom(other);
1030 }
1031
1032 void init(unsigned InitBuckets) {
1033 Small = true;
1034 if (InitBuckets > InlineBuckets) {
1035 Small = false;
1036 new (getLargeRep()) LargeRep(allocateBuckets(InitBuckets));
1037 }
1038 this->BaseT::initEmpty();
1039 }
1040
1041 void grow(unsigned AtLeast) {
1042 if (AtLeast > InlineBuckets)
1043 AtLeast = std::max<unsigned>(64, NextPowerOf2(AtLeast-1));
1044
1045 if (Small) {
1046 // First move the inline buckets into a temporary storage.
1047 AlignedCharArrayUnion<BucketT[InlineBuckets]> TmpStorage;
1048 BucketT *TmpBegin = reinterpret_cast<BucketT *>(&TmpStorage);
1049 BucketT *TmpEnd = TmpBegin;
1050
1051 // Loop over the buckets, moving non-empty, non-tombstones into the
1052 // temporary storage. Have the loop move the TmpEnd forward as it goes.
1053 const KeyT EmptyKey = this->getEmptyKey();
1054 const KeyT TombstoneKey = this->getTombstoneKey();
1055 for (BucketT *P = getBuckets(), *E = P + InlineBuckets; P != E; ++P) {
1056 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
1057 !KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
1058 assert(size_t(TmpEnd - TmpBegin) < InlineBuckets &&((void)0)
1059 "Too many inline buckets!")((void)0);
1060 ::new (&TmpEnd->getFirst()) KeyT(std::move(P->getFirst()));
1061 ::new (&TmpEnd->getSecond()) ValueT(std::move(P->getSecond()));
1062 ++TmpEnd;
1063 P->getSecond().~ValueT();
1064 }
1065 P->getFirst().~KeyT();
1066 }
1067
1068 // AtLeast == InlineBuckets can happen if there are many tombstones,
1069 // and grow() is used to remove them. Usually we always switch to the
1070 // large rep here.
1071 if (AtLeast > InlineBuckets) {
1072 Small = false;
1073 new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
1074 }
1075 this->moveFromOldBuckets(TmpBegin, TmpEnd);
1076 return;
1077 }
1078
1079 LargeRep OldRep = std::move(*getLargeRep());
1080 getLargeRep()->~LargeRep();
1081 if (AtLeast <= InlineBuckets) {
1082 Small = true;
1083 } else {
1084 new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
1085 }
1086
1087 this->moveFromOldBuckets(OldRep.Buckets, OldRep.Buckets+OldRep.NumBuckets);
1088
1089 // Free the old table.
1090 deallocate_buffer(OldRep.Buckets, sizeof(BucketT) * OldRep.NumBuckets,
1091 alignof(BucketT));
1092 }
1093
1094 void shrink_and_clear() {
1095 unsigned OldSize = this->size();
1096 this->destroyAll();
1097
1098 // Reduce the number of buckets.
1099 unsigned NewNumBuckets = 0;
1100 if (OldSize) {
1101 NewNumBuckets = 1 << (Log2_32_Ceil(OldSize) + 1);
1102 if (NewNumBuckets > InlineBuckets && NewNumBuckets < 64u)
1103 NewNumBuckets = 64;
1104 }
1105 if ((Small && NewNumBuckets <= InlineBuckets) ||
1106 (!Small && NewNumBuckets == getLargeRep()->NumBuckets)) {
1107 this->BaseT::initEmpty();
1108 return;
1109 }
1110
1111 deallocateBuckets();
1112 init(NewNumBuckets);
1113 }
1114
1115private:
1116 unsigned getNumEntries() const {
1117 return NumEntries;
1118 }
1119
1120 void setNumEntries(unsigned Num) {
1121 // NumEntries is hardcoded to be 31 bits wide.
1122 assert(Num < (1U << 31) && "Cannot support more than 1<<31 entries")((void)0);
1123 NumEntries = Num;
1124 }
1125
1126 unsigned getNumTombstones() const {
1127 return NumTombstones;
1128 }
1129
1130 void setNumTombstones(unsigned Num) {
1131 NumTombstones = Num;
1132 }
1133
1134 const BucketT *getInlineBuckets() const {
1135 assert(Small)((void)0);
1136 // Note that this cast does not violate aliasing rules as we assert that
1137 // the memory's dynamic type is the small, inline bucket buffer, and the
1138 // 'storage' is a POD containing a char buffer.
1139 return reinterpret_cast<const BucketT *>(&storage);
1140 }
1141
1142 BucketT *getInlineBuckets() {
1143 return const_cast<BucketT *>(
1144 const_cast<const SmallDenseMap *>(this)->getInlineBuckets());
1145 }
1146
1147 const LargeRep *getLargeRep() const {
1148 assert(!Small)((void)0);
1149 // Note, same rule about aliasing as with getInlineBuckets.
1150 return reinterpret_cast<const LargeRep *>(&storage);
1151 }
1152
1153 LargeRep *getLargeRep() {
1154 return const_cast<LargeRep *>(
1155 const_cast<const SmallDenseMap *>(this)->getLargeRep());
1156 }
1157
1158 const BucketT *getBuckets() const {
1159 return Small ? getInlineBuckets() : getLargeRep()->Buckets;
1160 }
1161
1162 BucketT *getBuckets() {
1163 return const_cast<BucketT *>(
1164 const_cast<const SmallDenseMap *>(this)->getBuckets());
1165 }
1166
1167 unsigned getNumBuckets() const {
1168 return Small ? InlineBuckets : getLargeRep()->NumBuckets;
1169 }
1170
1171 void deallocateBuckets() {
1172 if (Small)
1173 return;
1174
1175 deallocate_buffer(getLargeRep()->Buckets,
1176 sizeof(BucketT) * getLargeRep()->NumBuckets,
1177 alignof(BucketT));
1178 getLargeRep()->~LargeRep();
1179 }
1180
1181 LargeRep allocateBuckets(unsigned Num) {
1182 assert(Num > InlineBuckets && "Must allocate more buckets than are inline")((void)0);
1183 LargeRep Rep = {static_cast<BucketT *>(allocate_buffer(
1184 sizeof(BucketT) * Num, alignof(BucketT))),
1185 Num};
1186 return Rep;
1187 }
1188};
1189
1190template <typename KeyT, typename ValueT, typename KeyInfoT, typename Bucket,
1191 bool IsConst>
1192class DenseMapIterator : DebugEpochBase::HandleBase {
1193 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true>;
1194 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, false>;
1195
1196public:
1197 using difference_type = ptrdiff_t;
1198 using value_type =
1199 typename std::conditional<IsConst, const Bucket, Bucket>::type;
1200 using pointer = value_type *;
1201 using reference = value_type &;
1202 using iterator_category = std::forward_iterator_tag;
1203
1204private:
1205 pointer Ptr = nullptr;
1206 pointer End = nullptr;
1207
1208public:
1209 DenseMapIterator() = default;
1210
1211 DenseMapIterator(pointer Pos, pointer E, const DebugEpochBase &Epoch,
1212 bool NoAdvance = false)
1213 : DebugEpochBase::HandleBase(&Epoch), Ptr(Pos), End(E) {
1214 assert(isHandleInSync() && "invalid construction!")((void)0);
1215
1216 if (NoAdvance) return;
1217 if (shouldReverseIterate<KeyT>()) {
1218 RetreatPastEmptyBuckets();
1219 return;
1220 }
1221 AdvancePastEmptyBuckets();
1222 }
1223
1224 // Converting ctor from non-const iterators to const iterators. SFINAE'd out
1225 // for const iterator destinations so it doesn't end up as a user defined copy
1226 // constructor.
1227 template <bool IsConstSrc,
1228 typename = std::enable_if_t<!IsConstSrc && IsConst>>
1229 DenseMapIterator(
1230 const DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, IsConstSrc> &I)
1231 : DebugEpochBase::HandleBase(I), Ptr(I.Ptr), End(I.End) {}
1232
1233 reference operator*() const {
1234 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1235 assert(Ptr != End && "dereferencing end() iterator")((void)0);
1236 if (shouldReverseIterate<KeyT>())
1237 return Ptr[-1];
1238 return *Ptr;
1239 }
1240 pointer operator->() const {
1241 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1242 assert(Ptr != End && "dereferencing end() iterator")((void)0);
1243 if (shouldReverseIterate<KeyT>())
1244 return &(Ptr[-1]);
1245 return Ptr;
1246 }
1247
1248 friend bool operator==(const DenseMapIterator &LHS,
1249 const DenseMapIterator &RHS) {
1250 assert((!LHS.Ptr || LHS.isHandleInSync()) && "handle not in sync!")((void)0);
1251 assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!")((void)0);
1252 assert(LHS.getEpochAddress() == RHS.getEpochAddress() &&((void)0)
1253 "comparing incomparable iterators!")((void)0);
1254 return LHS.Ptr == RHS.Ptr;
52
Assuming 'LHS.Ptr' is not equal to 'RHS.Ptr'
53
Returning zero, which participates in a condition later
1255 }
1256
1257 friend bool operator!=(const DenseMapIterator &LHS,
1258 const DenseMapIterator &RHS) {
1259 return !(LHS == RHS);
51
Calling 'operator=='
54
Returning from 'operator=='
55
Returning the value 1, which participates in a condition later
1260 }
1261
1262 inline DenseMapIterator& operator++() { // Preincrement
1263 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1264 assert(Ptr != End && "incrementing end() iterator")((void)0);
1265 if (shouldReverseIterate<KeyT>()) {
1266 --Ptr;
1267 RetreatPastEmptyBuckets();
1268 return *this;
1269 }
1270 ++Ptr;
1271 AdvancePastEmptyBuckets();
1272 return *this;
1273 }
1274 DenseMapIterator operator++(int) { // Postincrement
1275 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1276 DenseMapIterator tmp = *this; ++*this; return tmp;
1277 }
1278
1279private:
1280 void AdvancePastEmptyBuckets() {
1281 assert(Ptr <= End)((void)0);
1282 const KeyT Empty = KeyInfoT::getEmptyKey();
1283 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1284
1285 while (Ptr != End && (KeyInfoT::isEqual(Ptr->getFirst(), Empty) ||
1286 KeyInfoT::isEqual(Ptr->getFirst(), Tombstone)))
1287 ++Ptr;
1288 }
1289
1290 void RetreatPastEmptyBuckets() {
1291 assert(Ptr >= End)((void)0);
1292 const KeyT Empty = KeyInfoT::getEmptyKey();
1293 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1294
1295 while (Ptr != End && (KeyInfoT::isEqual(Ptr[-1].getFirst(), Empty) ||
1296 KeyInfoT::isEqual(Ptr[-1].getFirst(), Tombstone)))
1297 --Ptr;
1298 }
1299};
1300
1301template <typename KeyT, typename ValueT, typename KeyInfoT>
1302inline size_t capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT> &X) {
1303 return X.getMemorySize();
1304}
1305
1306} // end namespace llvm
1307
1308#endif // LLVM_ADT_DENSEMAP_H