Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Analysis/MemorySSA.cpp
Warning:line 892, column 37
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 MemorySSA.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Analysis -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ASMParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/BinaryFormat -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitstream -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /include/llvm/CodeGen -I /include/llvm/CodeGen/PBQP -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Coroutines -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData/Coverage -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/CodeView -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/DWARF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/MSF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/PDB -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Demangle -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/JITLink -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/Orc -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenACC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenMP -I /include/llvm/CodeGen/GlobalISel -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IRReader -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/LTO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Linker -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC/MCParser -I /include/llvm/CodeGen/MIRParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Object -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Option -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Passes -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Scalar -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/Symbolize -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Target -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Utils -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Vectorize -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/IPO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libLLVM/../include -I /usr/src/gnu/usr.bin/clang/libLLVM/obj -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -D PIC -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -D_RET_PROTECTOR -ret-protector -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Analysis/MemorySSA.cpp

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Analysis/MemorySSA.cpp

1//===- MemorySSA.cpp - Memory SSA Builder ---------------------------------===//
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 implements the MemorySSA class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Analysis/MemorySSA.h"
14#include "llvm/ADT/DenseMap.h"
15#include "llvm/ADT/DenseMapInfo.h"
16#include "llvm/ADT/DenseSet.h"
17#include "llvm/ADT/DepthFirstIterator.h"
18#include "llvm/ADT/Hashing.h"
19#include "llvm/ADT/None.h"
20#include "llvm/ADT/Optional.h"
21#include "llvm/ADT/STLExtras.h"
22#include "llvm/ADT/SmallPtrSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/StringExtras.h"
25#include "llvm/ADT/iterator.h"
26#include "llvm/ADT/iterator_range.h"
27#include "llvm/Analysis/AliasAnalysis.h"
28#include "llvm/Analysis/CFGPrinter.h"
29#include "llvm/Analysis/IteratedDominanceFrontier.h"
30#include "llvm/Analysis/MemoryLocation.h"
31#include "llvm/Config/llvm-config.h"
32#include "llvm/IR/AssemblyAnnotationWriter.h"
33#include "llvm/IR/BasicBlock.h"
34#include "llvm/IR/Dominators.h"
35#include "llvm/IR/Function.h"
36#include "llvm/IR/Instruction.h"
37#include "llvm/IR/Instructions.h"
38#include "llvm/IR/IntrinsicInst.h"
39#include "llvm/IR/Intrinsics.h"
40#include "llvm/IR/LLVMContext.h"
41#include "llvm/IR/PassManager.h"
42#include "llvm/IR/Use.h"
43#include "llvm/InitializePasses.h"
44#include "llvm/Pass.h"
45#include "llvm/Support/AtomicOrdering.h"
46#include "llvm/Support/Casting.h"
47#include "llvm/Support/CommandLine.h"
48#include "llvm/Support/Compiler.h"
49#include "llvm/Support/Debug.h"
50#include "llvm/Support/ErrorHandling.h"
51#include "llvm/Support/FormattedStream.h"
52#include "llvm/Support/raw_ostream.h"
53#include <algorithm>
54#include <cassert>
55#include <cstdlib>
56#include <iterator>
57#include <memory>
58#include <utility>
59
60using namespace llvm;
61
62#define DEBUG_TYPE"memoryssa" "memoryssa"
63
64static cl::opt<std::string>
65 DotCFGMSSA("dot-cfg-mssa",
66 cl::value_desc("file name for generated dot file"),
67 cl::desc("file name for generated dot file"), cl::init(""));
68
69INITIALIZE_PASS_BEGIN(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
&Registry) {
70 true)static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
&Registry) {
71INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
72INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)initializeAAResultsWrapperPassPass(Registry);
73INITIALIZE_PASS_END(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,PassInfo *PI = new PassInfo( "Memory SSA", "memoryssa", &
MemorySSAWrapperPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MemorySSAWrapperPass>), false, true); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMemorySSAWrapperPassPassFlag
; void llvm::initializeMemorySSAWrapperPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAWrapperPassPassFlag
, initializeMemorySSAWrapperPassPassOnce, std::ref(Registry))
; }
74 true)PassInfo *PI = new PassInfo( "Memory SSA", "memoryssa", &
MemorySSAWrapperPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MemorySSAWrapperPass>), false, true); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMemorySSAWrapperPassPassFlag
; void llvm::initializeMemorySSAWrapperPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAWrapperPassPassFlag
, initializeMemorySSAWrapperPassPassOnce, std::ref(Registry))
; }
75
76INITIALIZE_PASS_BEGIN(MemorySSAPrinterLegacyPass, "print-memoryssa",static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
&Registry) {
77 "Memory SSA Printer", false, false)static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
&Registry) {
78INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)initializeMemorySSAWrapperPassPass(Registry);
79INITIALIZE_PASS_END(MemorySSAPrinterLegacyPass, "print-memoryssa",PassInfo *PI = new PassInfo( "Memory SSA Printer", "print-memoryssa"
, &MemorySSAPrinterLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<MemorySSAPrinterLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeMemorySSAPrinterLegacyPassPassFlag; void
llvm::initializeMemorySSAPrinterLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAPrinterLegacyPassPassFlag
, initializeMemorySSAPrinterLegacyPassPassOnce, std::ref(Registry
)); }
80 "Memory SSA Printer", false, false)PassInfo *PI = new PassInfo( "Memory SSA Printer", "print-memoryssa"
, &MemorySSAPrinterLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<MemorySSAPrinterLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeMemorySSAPrinterLegacyPassPassFlag; void
llvm::initializeMemorySSAPrinterLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeMemorySSAPrinterLegacyPassPassFlag
, initializeMemorySSAPrinterLegacyPassPassOnce, std::ref(Registry
)); }
81
82static cl::opt<unsigned> MaxCheckLimit(
83 "memssa-check-limit", cl::Hidden, cl::init(100),
84 cl::desc("The maximum number of stores/phis MemorySSA"
85 "will consider trying to walk past (default = 100)"));
86
87// Always verify MemorySSA if expensive checking is enabled.
88#ifdef EXPENSIVE_CHECKS
89bool llvm::VerifyMemorySSA = true;
90#else
91bool llvm::VerifyMemorySSA = false;
92#endif
93/// Enables memory ssa as a dependency for loop passes in legacy pass manager.
94cl::opt<bool> llvm::EnableMSSALoopDependency(
95 "enable-mssa-loop-dependency", cl::Hidden, cl::init(true),
96 cl::desc("Enable MemorySSA dependency for loop pass manager"));
97
98static cl::opt<bool, true>
99 VerifyMemorySSAX("verify-memoryssa", cl::location(VerifyMemorySSA),
100 cl::Hidden, cl::desc("Enable verification of MemorySSA."));
101
102namespace llvm {
103
104/// An assembly annotator class to print Memory SSA information in
105/// comments.
106class MemorySSAAnnotatedWriter : public AssemblyAnnotationWriter {
107 friend class MemorySSA;
108
109 const MemorySSA *MSSA;
110
111public:
112 MemorySSAAnnotatedWriter(const MemorySSA *M) : MSSA(M) {}
113
114 void emitBasicBlockStartAnnot(const BasicBlock *BB,
115 formatted_raw_ostream &OS) override {
116 if (MemoryAccess *MA = MSSA->getMemoryAccess(BB))
117 OS << "; " << *MA << "\n";
118 }
119
120 void emitInstructionAnnot(const Instruction *I,
121 formatted_raw_ostream &OS) override {
122 if (MemoryAccess *MA = MSSA->getMemoryAccess(I))
123 OS << "; " << *MA << "\n";
124 }
125};
126
127} // end namespace llvm
128
129namespace {
130
131/// Our current alias analysis API differentiates heavily between calls and
132/// non-calls, and functions called on one usually assert on the other.
133/// This class encapsulates the distinction to simplify other code that wants
134/// "Memory affecting instructions and related data" to use as a key.
135/// For example, this class is used as a densemap key in the use optimizer.
136class MemoryLocOrCall {
137public:
138 bool IsCall = false;
139
140 MemoryLocOrCall(MemoryUseOrDef *MUD)
141 : MemoryLocOrCall(MUD->getMemoryInst()) {}
142 MemoryLocOrCall(const MemoryUseOrDef *MUD)
143 : MemoryLocOrCall(MUD->getMemoryInst()) {}
144
145 MemoryLocOrCall(Instruction *Inst) {
146 if (auto *C = dyn_cast<CallBase>(Inst)) {
147 IsCall = true;
148 Call = C;
149 } else {
150 IsCall = false;
151 // There is no such thing as a memorylocation for a fence inst, and it is
152 // unique in that regard.
153 if (!isa<FenceInst>(Inst))
154 Loc = MemoryLocation::get(Inst);
155 }
156 }
157
158 explicit MemoryLocOrCall(const MemoryLocation &Loc) : Loc(Loc) {}
159
160 const CallBase *getCall() const {
161 assert(IsCall)((void)0);
162 return Call;
163 }
164
165 MemoryLocation getLoc() const {
166 assert(!IsCall)((void)0);
167 return Loc;
168 }
169
170 bool operator==(const MemoryLocOrCall &Other) const {
171 if (IsCall != Other.IsCall)
172 return false;
173
174 if (!IsCall)
175 return Loc == Other.Loc;
176
177 if (Call->getCalledOperand() != Other.Call->getCalledOperand())
178 return false;
179
180 return Call->arg_size() == Other.Call->arg_size() &&
181 std::equal(Call->arg_begin(), Call->arg_end(),
182 Other.Call->arg_begin());
183 }
184
185private:
186 union {
187 const CallBase *Call;
188 MemoryLocation Loc;
189 };
190};
191
192} // end anonymous namespace
193
194namespace llvm {
195
196template <> struct DenseMapInfo<MemoryLocOrCall> {
197 static inline MemoryLocOrCall getEmptyKey() {
198 return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getEmptyKey());
199 }
200
201 static inline MemoryLocOrCall getTombstoneKey() {
202 return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getTombstoneKey());
203 }
204
205 static unsigned getHashValue(const MemoryLocOrCall &MLOC) {
206 if (!MLOC.IsCall)
207 return hash_combine(
208 MLOC.IsCall,
209 DenseMapInfo<MemoryLocation>::getHashValue(MLOC.getLoc()));
210
211 hash_code hash =
212 hash_combine(MLOC.IsCall, DenseMapInfo<const Value *>::getHashValue(
213 MLOC.getCall()->getCalledOperand()));
214
215 for (const Value *Arg : MLOC.getCall()->args())
216 hash = hash_combine(hash, DenseMapInfo<const Value *>::getHashValue(Arg));
217 return hash;
218 }
219
220 static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) {
221 return LHS == RHS;
222 }
223};
224
225} // end namespace llvm
226
227/// This does one-way checks to see if Use could theoretically be hoisted above
228/// MayClobber. This will not check the other way around.
229///
230/// This assumes that, for the purposes of MemorySSA, Use comes directly after
231/// MayClobber, with no potentially clobbering operations in between them.
232/// (Where potentially clobbering ops are memory barriers, aliased stores, etc.)
233static bool areLoadsReorderable(const LoadInst *Use,
234 const LoadInst *MayClobber) {
235 bool VolatileUse = Use->isVolatile();
236 bool VolatileClobber = MayClobber->isVolatile();
237 // Volatile operations may never be reordered with other volatile operations.
238 if (VolatileUse && VolatileClobber)
239 return false;
240 // Otherwise, volatile doesn't matter here. From the language reference:
241 // 'optimizers may change the order of volatile operations relative to
242 // non-volatile operations.'"
243
244 // If a load is seq_cst, it cannot be moved above other loads. If its ordering
245 // is weaker, it can be moved above other loads. We just need to be sure that
246 // MayClobber isn't an acquire load, because loads can't be moved above
247 // acquire loads.
248 //
249 // Note that this explicitly *does* allow the free reordering of monotonic (or
250 // weaker) loads of the same address.
251 bool SeqCstUse = Use->getOrdering() == AtomicOrdering::SequentiallyConsistent;
252 bool MayClobberIsAcquire = isAtLeastOrStrongerThan(MayClobber->getOrdering(),
253 AtomicOrdering::Acquire);
254 return !(SeqCstUse || MayClobberIsAcquire);
255}
256
257namespace {
258
259struct ClobberAlias {
260 bool IsClobber;
261 Optional<AliasResult> AR;
262};
263
264} // end anonymous namespace
265
266// Return a pair of {IsClobber (bool), AR (AliasResult)}. It relies on AR being
267// ignored if IsClobber = false.
268template <typename AliasAnalysisType>
269static ClobberAlias
270instructionClobbersQuery(const MemoryDef *MD, const MemoryLocation &UseLoc,
271 const Instruction *UseInst, AliasAnalysisType &AA) {
272 Instruction *DefInst = MD->getMemoryInst();
273 assert(DefInst && "Defining instruction not actually an instruction")((void)0);
274 Optional<AliasResult> AR;
275
276 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(DefInst)) {
277 // These intrinsics will show up as affecting memory, but they are just
278 // markers, mostly.
279 //
280 // FIXME: We probably don't actually want MemorySSA to model these at all
281 // (including creating MemoryAccesses for them): we just end up inventing
282 // clobbers where they don't really exist at all. Please see D43269 for
283 // context.
284 switch (II->getIntrinsicID()) {
285 case Intrinsic::invariant_start:
286 case Intrinsic::invariant_end:
287 case Intrinsic::assume:
288 case Intrinsic::experimental_noalias_scope_decl:
289 return {false, AliasResult(AliasResult::NoAlias)};
290 case Intrinsic::dbg_addr:
291 case Intrinsic::dbg_declare:
292 case Intrinsic::dbg_label:
293 case Intrinsic::dbg_value:
294 llvm_unreachable("debuginfo shouldn't have associated defs!")__builtin_unreachable();
295 default:
296 break;
297 }
298 }
299
300 if (auto *CB = dyn_cast_or_null<CallBase>(UseInst)) {
301 ModRefInfo I = AA.getModRefInfo(DefInst, CB);
302 AR = isMustSet(I) ? AliasResult::MustAlias : AliasResult::MayAlias;
303 return {isModOrRefSet(I), AR};
304 }
305
306 if (auto *DefLoad = dyn_cast<LoadInst>(DefInst))
307 if (auto *UseLoad = dyn_cast_or_null<LoadInst>(UseInst))
308 return {!areLoadsReorderable(UseLoad, DefLoad),
309 AliasResult(AliasResult::MayAlias)};
310
311 ModRefInfo I = AA.getModRefInfo(DefInst, UseLoc);
312 AR = isMustSet(I) ? AliasResult::MustAlias : AliasResult::MayAlias;
313 return {isModSet(I), AR};
314}
315
316template <typename AliasAnalysisType>
317static ClobberAlias instructionClobbersQuery(MemoryDef *MD,
318 const MemoryUseOrDef *MU,
319 const MemoryLocOrCall &UseMLOC,
320 AliasAnalysisType &AA) {
321 // FIXME: This is a temporary hack to allow a single instructionClobbersQuery
322 // to exist while MemoryLocOrCall is pushed through places.
323 if (UseMLOC.IsCall)
324 return instructionClobbersQuery(MD, MemoryLocation(), MU->getMemoryInst(),
325 AA);
326 return instructionClobbersQuery(MD, UseMLOC.getLoc(), MU->getMemoryInst(),
327 AA);
328}
329
330// Return true when MD may alias MU, return false otherwise.
331bool MemorySSAUtil::defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU,
332 AliasAnalysis &AA) {
333 return instructionClobbersQuery(MD, MU, MemoryLocOrCall(MU), AA).IsClobber;
334}
335
336namespace {
337
338struct UpwardsMemoryQuery {
339 // True if our original query started off as a call
340 bool IsCall = false;
341 // The pointer location we started the query with. This will be empty if
342 // IsCall is true.
343 MemoryLocation StartingLoc;
344 // This is the instruction we were querying about.
345 const Instruction *Inst = nullptr;
346 // The MemoryAccess we actually got called with, used to test local domination
347 const MemoryAccess *OriginalAccess = nullptr;
348 Optional<AliasResult> AR = AliasResult(AliasResult::MayAlias);
349 bool SkipSelfAccess = false;
350
351 UpwardsMemoryQuery() = default;
352
353 UpwardsMemoryQuery(const Instruction *Inst, const MemoryAccess *Access)
354 : IsCall(isa<CallBase>(Inst)), Inst(Inst), OriginalAccess(Access) {
355 if (!IsCall)
356 StartingLoc = MemoryLocation::get(Inst);
357 }
358};
359
360} // end anonymous namespace
361
362template <typename AliasAnalysisType>
363static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysisType &AA,
364 const Instruction *I) {
365 // If the memory can't be changed, then loads of the memory can't be
366 // clobbered.
367 if (auto *LI = dyn_cast<LoadInst>(I))
368 return I->hasMetadata(LLVMContext::MD_invariant_load) ||
369 AA.pointsToConstantMemory(MemoryLocation::get(LI));
370 return false;
371}
372
373/// Verifies that `Start` is clobbered by `ClobberAt`, and that nothing
374/// inbetween `Start` and `ClobberAt` can clobbers `Start`.
375///
376/// This is meant to be as simple and self-contained as possible. Because it
377/// uses no cache, etc., it can be relatively expensive.
378///
379/// \param Start The MemoryAccess that we want to walk from.
380/// \param ClobberAt A clobber for Start.
381/// \param StartLoc The MemoryLocation for Start.
382/// \param MSSA The MemorySSA instance that Start and ClobberAt belong to.
383/// \param Query The UpwardsMemoryQuery we used for our search.
384/// \param AA The AliasAnalysis we used for our search.
385/// \param AllowImpreciseClobber Always false, unless we do relaxed verify.
386
387template <typename AliasAnalysisType>
388LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) static void
389checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt,
390 const MemoryLocation &StartLoc, const MemorySSA &MSSA,
391 const UpwardsMemoryQuery &Query, AliasAnalysisType &AA,
392 bool AllowImpreciseClobber = false) {
393 assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?")((void)0);
394
395 if (MSSA.isLiveOnEntryDef(Start)) {
396 assert(MSSA.isLiveOnEntryDef(ClobberAt) &&((void)0)
397 "liveOnEntry must clobber itself")((void)0);
398 return;
399 }
400
401 bool FoundClobber = false;
402 DenseSet<ConstMemoryAccessPair> VisitedPhis;
403 SmallVector<ConstMemoryAccessPair, 8> Worklist;
404 Worklist.emplace_back(Start, StartLoc);
405 // Walk all paths from Start to ClobberAt, while looking for clobbers. If one
406 // is found, complain.
407 while (!Worklist.empty()) {
408 auto MAP = Worklist.pop_back_val();
409 // All we care about is that nothing from Start to ClobberAt clobbers Start.
410 // We learn nothing from revisiting nodes.
411 if (!VisitedPhis.insert(MAP).second)
412 continue;
413
414 for (const auto *MA : def_chain(MAP.first)) {
415 if (MA == ClobberAt) {
416 if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
417 // instructionClobbersQuery isn't essentially free, so don't use `|=`,
418 // since it won't let us short-circuit.
419 //
420 // Also, note that this can't be hoisted out of the `Worklist` loop,
421 // since MD may only act as a clobber for 1 of N MemoryLocations.
422 FoundClobber = FoundClobber || MSSA.isLiveOnEntryDef(MD);
423 if (!FoundClobber) {
424 ClobberAlias CA =
425 instructionClobbersQuery(MD, MAP.second, Query.Inst, AA);
426 if (CA.IsClobber) {
427 FoundClobber = true;
428 // Not used: CA.AR;
429 }
430 }
431 }
432 break;
433 }
434
435 // We should never hit liveOnEntry, unless it's the clobber.
436 assert(!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?")((void)0);
437
438 if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
439 // If Start is a Def, skip self.
440 if (MD == Start)
441 continue;
442
443 assert(!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA)((void)0)
444 .IsClobber &&((void)0)
445 "Found clobber before reaching ClobberAt!")((void)0);
446 continue;
447 }
448
449 if (const auto *MU = dyn_cast<MemoryUse>(MA)) {
450 (void)MU;
451 assert (MU == Start &&((void)0)
452 "Can only find use in def chain if Start is a use")((void)0);
453 continue;
454 }
455
456 assert(isa<MemoryPhi>(MA))((void)0);
457
458 // Add reachable phi predecessors
459 for (auto ItB = upward_defs_begin(
460 {const_cast<MemoryAccess *>(MA), MAP.second},
461 MSSA.getDomTree()),
462 ItE = upward_defs_end();
463 ItB != ItE; ++ItB)
464 if (MSSA.getDomTree().isReachableFromEntry(ItB.getPhiArgBlock()))
465 Worklist.emplace_back(*ItB);
466 }
467 }
468
469 // If the verify is done following an optimization, it's possible that
470 // ClobberAt was a conservative clobbering, that we can now infer is not a
471 // true clobbering access. Don't fail the verify if that's the case.
472 // We do have accesses that claim they're optimized, but could be optimized
473 // further. Updating all these can be expensive, so allow it for now (FIXME).
474 if (AllowImpreciseClobber)
475 return;
476
477 // If ClobberAt is a MemoryPhi, we can assume something above it acted as a
478 // clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point.
479 assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&((void)0)
480 "ClobberAt never acted as a clobber")((void)0);
481}
482
483namespace {
484
485/// Our algorithm for walking (and trying to optimize) clobbers, all wrapped up
486/// in one class.
487template <class AliasAnalysisType> class ClobberWalker {
488 /// Save a few bytes by using unsigned instead of size_t.
489 using ListIndex = unsigned;
490
491 /// Represents a span of contiguous MemoryDefs, potentially ending in a
492 /// MemoryPhi.
493 struct DefPath {
494 MemoryLocation Loc;
495 // Note that, because we always walk in reverse, Last will always dominate
496 // First. Also note that First and Last are inclusive.
497 MemoryAccess *First;
498 MemoryAccess *Last;
499 Optional<ListIndex> Previous;
500
501 DefPath(const MemoryLocation &Loc, MemoryAccess *First, MemoryAccess *Last,
502 Optional<ListIndex> Previous)
503 : Loc(Loc), First(First), Last(Last), Previous(Previous) {}
504
505 DefPath(const MemoryLocation &Loc, MemoryAccess *Init,
506 Optional<ListIndex> Previous)
507 : DefPath(Loc, Init, Init, Previous) {}
508 };
509
510 const MemorySSA &MSSA;
511 AliasAnalysisType &AA;
512 DominatorTree &DT;
513 UpwardsMemoryQuery *Query;
514 unsigned *UpwardWalkLimit;
515
516 // Phi optimization bookkeeping:
517 // List of DefPath to process during the current phi optimization walk.
518 SmallVector<DefPath, 32> Paths;
519 // List of visited <Access, Location> pairs; we can skip paths already
520 // visited with the same memory location.
521 DenseSet<ConstMemoryAccessPair> VisitedPhis;
522 // Record if phi translation has been performed during the current phi
523 // optimization walk, as merging alias results after phi translation can
524 // yield incorrect results. Context in PR46156.
525 bool PerformedPhiTranslation = false;
526
527 /// Find the nearest def or phi that `From` can legally be optimized to.
528 const MemoryAccess *getWalkTarget(const MemoryPhi *From) const {
529 assert(From->getNumOperands() && "Phi with no operands?")((void)0);
530
531 BasicBlock *BB = From->getBlock();
532 MemoryAccess *Result = MSSA.getLiveOnEntryDef();
533 DomTreeNode *Node = DT.getNode(BB);
534 while ((Node = Node->getIDom())) {
535 auto *Defs = MSSA.getBlockDefs(Node->getBlock());
536 if (Defs)
537 return &*Defs->rbegin();
538 }
539 return Result;
540 }
541
542 /// Result of calling walkToPhiOrClobber.
543 struct UpwardsWalkResult {
544 /// The "Result" of the walk. Either a clobber, the last thing we walked, or
545 /// both. Include alias info when clobber found.
546 MemoryAccess *Result;
547 bool IsKnownClobber;
548 Optional<AliasResult> AR;
549 };
550
551 /// Walk to the next Phi or Clobber in the def chain starting at Desc.Last.
552 /// This will update Desc.Last as it walks. It will (optionally) also stop at
553 /// StopAt.
554 ///
555 /// This does not test for whether StopAt is a clobber
556 UpwardsWalkResult
557 walkToPhiOrClobber(DefPath &Desc, const MemoryAccess *StopAt = nullptr,
558 const MemoryAccess *SkipStopAt = nullptr) const {
559 assert(!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world")((void)0);
560 assert(UpwardWalkLimit && "Need a valid walk limit")((void)0);
561 bool LimitAlreadyReached = false;
562 // (*UpwardWalkLimit) may be 0 here, due to the loop in tryOptimizePhi. Set
563 // it to 1. This will not do any alias() calls. It either returns in the
564 // first iteration in the loop below, or is set back to 0 if all def chains
565 // are free of MemoryDefs.
566 if (!*UpwardWalkLimit) {
567 *UpwardWalkLimit = 1;
568 LimitAlreadyReached = true;
569 }
570
571 for (MemoryAccess *Current : def_chain(Desc.Last)) {
572 Desc.Last = Current;
573 if (Current == StopAt || Current == SkipStopAt)
574 return {Current, false, AliasResult(AliasResult::MayAlias)};
575
576 if (auto *MD = dyn_cast<MemoryDef>(Current)) {
577 if (MSSA.isLiveOnEntryDef(MD))
578 return {MD, true, AliasResult(AliasResult::MustAlias)};
579
580 if (!--*UpwardWalkLimit)
581 return {Current, true, AliasResult(AliasResult::MayAlias)};
582
583 ClobberAlias CA =
584 instructionClobbersQuery(MD, Desc.Loc, Query->Inst, AA);
585 if (CA.IsClobber)
586 return {MD, true, CA.AR};
587 }
588 }
589
590 if (LimitAlreadyReached)
591 *UpwardWalkLimit = 0;
592
593 assert(isa<MemoryPhi>(Desc.Last) &&((void)0)
594 "Ended at a non-clobber that's not a phi?")((void)0);
595 return {Desc.Last, false, AliasResult(AliasResult::MayAlias)};
596 }
597
598 void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches,
599 ListIndex PriorNode) {
600 auto UpwardDefsBegin = upward_defs_begin({Phi, Paths[PriorNode].Loc}, DT,
601 &PerformedPhiTranslation);
602 auto UpwardDefs = make_range(UpwardDefsBegin, upward_defs_end());
603 for (const MemoryAccessPair &P : UpwardDefs) {
604 PausedSearches.push_back(Paths.size());
605 Paths.emplace_back(P.second, P.first, PriorNode);
606 }
607 }
608
609 /// Represents a search that terminated after finding a clobber. This clobber
610 /// may or may not be present in the path of defs from LastNode..SearchStart,
611 /// since it may have been retrieved from cache.
612 struct TerminatedPath {
613 MemoryAccess *Clobber;
614 ListIndex LastNode;
615 };
616
617 /// Get an access that keeps us from optimizing to the given phi.
618 ///
619 /// PausedSearches is an array of indices into the Paths array. Its incoming
620 /// value is the indices of searches that stopped at the last phi optimization
621 /// target. It's left in an unspecified state.
622 ///
623 /// If this returns None, NewPaused is a vector of searches that terminated
624 /// at StopWhere. Otherwise, NewPaused is left in an unspecified state.
625 Optional<TerminatedPath>
626 getBlockingAccess(const MemoryAccess *StopWhere,
627 SmallVectorImpl<ListIndex> &PausedSearches,
628 SmallVectorImpl<ListIndex> &NewPaused,
629 SmallVectorImpl<TerminatedPath> &Terminated) {
630 assert(!PausedSearches.empty() && "No searches to continue?")((void)0);
631
632 // BFS vs DFS really doesn't make a difference here, so just do a DFS with
633 // PausedSearches as our stack.
634 while (!PausedSearches.empty()) {
15
Loop condition is false. Execution continues on line 704
635 ListIndex PathIndex = PausedSearches.pop_back_val();
636 DefPath &Node = Paths[PathIndex];
637
638 // If we've already visited this path with this MemoryLocation, we don't
639 // need to do so again.
640 //
641 // NOTE: That we just drop these paths on the ground makes caching
642 // behavior sporadic. e.g. given a diamond:
643 // A
644 // B C
645 // D
646 //
647 // ...If we walk D, B, A, C, we'll only cache the result of phi
648 // optimization for A, B, and D; C will be skipped because it dies here.
649 // This arguably isn't the worst thing ever, since:
650 // - We generally query things in a top-down order, so if we got below D
651 // without needing cache entries for {C, MemLoc}, then chances are
652 // that those cache entries would end up ultimately unused.
653 // - We still cache things for A, so C only needs to walk up a bit.
654 // If this behavior becomes problematic, we can fix without a ton of extra
655 // work.
656 if (!VisitedPhis.insert({Node.Last, Node.Loc}).second) {
657 if (PerformedPhiTranslation) {
658 // If visiting this path performed Phi translation, don't continue,
659 // since it may not be correct to merge results from two paths if one
660 // relies on the phi translation.
661 TerminatedPath Term{Node.Last, PathIndex};
662 return Term;
663 }
664 continue;
665 }
666
667 const MemoryAccess *SkipStopWhere = nullptr;
668 if (Query->SkipSelfAccess && Node.Loc == Query->StartingLoc) {
669 assert(isa<MemoryDef>(Query->OriginalAccess))((void)0);
670 SkipStopWhere = Query->OriginalAccess;
671 }
672
673 UpwardsWalkResult Res = walkToPhiOrClobber(Node,
674 /*StopAt=*/StopWhere,
675 /*SkipStopAt=*/SkipStopWhere);
676 if (Res.IsKnownClobber) {
677 assert(Res.Result != StopWhere && Res.Result != SkipStopWhere)((void)0);
678
679 // If this wasn't a cache hit, we hit a clobber when walking. That's a
680 // failure.
681 TerminatedPath Term{Res.Result, PathIndex};
682 if (!MSSA.dominates(Res.Result, StopWhere))
683 return Term;
684
685 // Otherwise, it's a valid thing to potentially optimize to.
686 Terminated.push_back(Term);
687 continue;
688 }
689
690 if (Res.Result == StopWhere || Res.Result == SkipStopWhere) {
691 // We've hit our target. Save this path off for if we want to continue
692 // walking. If we are in the mode of skipping the OriginalAccess, and
693 // we've reached back to the OriginalAccess, do not save path, we've
694 // just looped back to self.
695 if (Res.Result != SkipStopWhere)
696 NewPaused.push_back(PathIndex);
697 continue;
698 }
699
700 assert(!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber")((void)0);
701 addSearches(cast<MemoryPhi>(Res.Result), PausedSearches, PathIndex);
702 }
703
704 return None;
16
Returning without writing to 'NewPaused.Size', which participates in a condition later
17
Returning without writing to 'Terminated.Size', which participates in a condition later
705 }
706
707 template <typename T, typename Walker>
708 struct generic_def_path_iterator
709 : public iterator_facade_base<generic_def_path_iterator<T, Walker>,
710 std::forward_iterator_tag, T *> {
711 generic_def_path_iterator() {}
712 generic_def_path_iterator(Walker *W, ListIndex N) : W(W), N(N) {}
713
714 T &operator*() const { return curNode(); }
715
716 generic_def_path_iterator &operator++() {
717 N = curNode().Previous;
718 return *this;
719 }
720
721 bool operator==(const generic_def_path_iterator &O) const {
722 if (N.hasValue() != O.N.hasValue())
723 return false;
724 return !N.hasValue() || *N == *O.N;
725 }
726
727 private:
728 T &curNode() const { return W->Paths[*N]; }
729
730 Walker *W = nullptr;
731 Optional<ListIndex> N = None;
732 };
733
734 using def_path_iterator = generic_def_path_iterator<DefPath, ClobberWalker>;
735 using const_def_path_iterator =
736 generic_def_path_iterator<const DefPath, const ClobberWalker>;
737
738 iterator_range<def_path_iterator> def_path(ListIndex From) {
739 return make_range(def_path_iterator(this, From), def_path_iterator());
740 }
741
742 iterator_range<const_def_path_iterator> const_def_path(ListIndex From) const {
743 return make_range(const_def_path_iterator(this, From),
744 const_def_path_iterator());
745 }
746
747 struct OptznResult {
748 /// The path that contains our result.
749 TerminatedPath PrimaryClobber;
750 /// The paths that we can legally cache back from, but that aren't
751 /// necessarily the result of the Phi optimization.
752 SmallVector<TerminatedPath, 4> OtherClobbers;
753 };
754
755 ListIndex defPathIndex(const DefPath &N) const {
756 // The assert looks nicer if we don't need to do &N
757 const DefPath *NP = &N;
758 assert(!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() &&((void)0)
759 "Out of bounds DefPath!")((void)0);
760 return NP - &Paths.front();
761 }
762
763 /// Try to optimize a phi as best as we can. Returns a SmallVector of Paths
764 /// that act as legal clobbers. Note that this won't return *all* clobbers.
765 ///
766 /// Phi optimization algorithm tl;dr:
767 /// - Find the earliest def/phi, A, we can optimize to
768 /// - Find if all paths from the starting memory access ultimately reach A
769 /// - If not, optimization isn't possible.
770 /// - Otherwise, walk from A to another clobber or phi, A'.
771 /// - If A' is a def, we're done.
772 /// - If A' is a phi, try to optimize it.
773 ///
774 /// A path is a series of {MemoryAccess, MemoryLocation} pairs. A path
775 /// terminates when a MemoryAccess that clobbers said MemoryLocation is found.
776 OptznResult tryOptimizePhi(MemoryPhi *Phi, MemoryAccess *Start,
777 const MemoryLocation &Loc) {
778 assert(Paths.empty() && VisitedPhis.empty() && !PerformedPhiTranslation &&((void)0)
779 "Reset the optimization state.")((void)0);
780
781 Paths.emplace_back(Loc, Start, Phi, None);
782 // Stores how many "valid" optimization nodes we had prior to calling
783 // addSearches/getBlockingAccess. Necessary for caching if we had a blocker.
784 auto PriorPathsSize = Paths.size();
785
786 SmallVector<ListIndex, 16> PausedSearches;
787 SmallVector<ListIndex, 8> NewPaused;
788 SmallVector<TerminatedPath, 4> TerminatedPaths;
789
790 addSearches(Phi, PausedSearches, 0);
791
792 // Moves the TerminatedPath with the "most dominated" Clobber to the end of
793 // Paths.
794 auto MoveDominatedPathToEnd = [&](SmallVectorImpl<TerminatedPath> &Paths) {
795 assert(!Paths.empty() && "Need a path to move")((void)0);
796 auto Dom = Paths.begin();
797 for (auto I = std::next(Dom), E = Paths.end(); I != E; ++I)
798 if (!MSSA.dominates(I->Clobber, Dom->Clobber))
799 Dom = I;
800 auto Last = Paths.end() - 1;
801 if (Last != Dom)
802 std::iter_swap(Last, Dom);
803 };
804
805 MemoryPhi *Current = Phi;
806 while (true) {
13
Loop condition is true. Entering loop body
807 assert(!MSSA.isLiveOnEntryDef(Current) &&((void)0)
808 "liveOnEntry wasn't treated as a clobber?")((void)0);
809
810 const auto *Target = getWalkTarget(Current);
811 // If a TerminatedPath doesn't dominate Target, then it wasn't a legal
812 // optimization for the prior phi.
813 assert(all_of(TerminatedPaths, [&](const TerminatedPath &P) {((void)0)
814 return MSSA.dominates(P.Clobber, Target);((void)0)
815 }))((void)0);
816
817 // FIXME: This is broken, because the Blocker may be reported to be
818 // liveOnEntry, and we'll happily wait for that to disappear (read: never)
819 // For the moment, this is fine, since we do nothing with blocker info.
820 if (Optional<TerminatedPath> Blocker = getBlockingAccess(
14
Calling 'ClobberWalker::getBlockingAccess'
18
Returning from 'ClobberWalker::getBlockingAccess'
19
Calling 'Optional::operator bool'
27
Returning from 'Optional::operator bool'
28
Taking false branch
821 Target, PausedSearches, NewPaused, TerminatedPaths)) {
822
823 // Find the node we started at. We can't search based on N->Last, since
824 // we may have gone around a loop with a different MemoryLocation.
825 auto Iter = find_if(def_path(Blocker->LastNode), [&](const DefPath &N) {
826 return defPathIndex(N) < PriorPathsSize;
827 });
828 assert(Iter != def_path_iterator())((void)0);
829
830 DefPath &CurNode = *Iter;
831 assert(CurNode.Last == Current)((void)0);
832
833 // Two things:
834 // A. We can't reliably cache all of NewPaused back. Consider a case
835 // where we have two paths in NewPaused; one of which can't optimize
836 // above this phi, whereas the other can. If we cache the second path
837 // back, we'll end up with suboptimal cache entries. We can handle
838 // cases like this a bit better when we either try to find all
839 // clobbers that block phi optimization, or when our cache starts
840 // supporting unfinished searches.
841 // B. We can't reliably cache TerminatedPaths back here without doing
842 // extra checks; consider a case like:
843 // T
844 // / \
845 // D C
846 // \ /
847 // S
848 // Where T is our target, C is a node with a clobber on it, D is a
849 // diamond (with a clobber *only* on the left or right node, N), and
850 // S is our start. Say we walk to D, through the node opposite N
851 // (read: ignoring the clobber), and see a cache entry in the top
852 // node of D. That cache entry gets put into TerminatedPaths. We then
853 // walk up to C (N is later in our worklist), find the clobber, and
854 // quit. If we append TerminatedPaths to OtherClobbers, we'll cache
855 // the bottom part of D to the cached clobber, ignoring the clobber
856 // in N. Again, this problem goes away if we start tracking all
857 // blockers for a given phi optimization.
858 TerminatedPath Result{CurNode.Last, defPathIndex(CurNode)};
859 return {Result, {}};
860 }
861
862 // If there's nothing left to search, then all paths led to valid clobbers
863 // that we got from our cache; pick the nearest to the start, and allow
864 // the rest to be cached back.
865 if (NewPaused.empty()) {
29
Calling 'SmallVectorBase::empty'
32
Returning from 'SmallVectorBase::empty'
33
Taking false branch
866 MoveDominatedPathToEnd(TerminatedPaths);
867 TerminatedPath Result = TerminatedPaths.pop_back_val();
868 return {Result, std::move(TerminatedPaths)};
869 }
870
871 MemoryAccess *DefChainEnd = nullptr;
34
'DefChainEnd' initialized to a null pointer value
872 SmallVector<TerminatedPath, 4> Clobbers;
873 for (ListIndex Paused : NewPaused) {
35
Assuming '__begin3' is equal to '__end3'
874 UpwardsWalkResult WR = walkToPhiOrClobber(Paths[Paused]);
875 if (WR.IsKnownClobber)
876 Clobbers.push_back({WR.Result, Paused});
877 else
878 // Micro-opt: If we hit the end of the chain, save it.
879 DefChainEnd = WR.Result;
880 }
881
882 if (!TerminatedPaths.empty()) {
36
Calling 'SmallVectorBase::empty'
39
Returning from 'SmallVectorBase::empty'
40
Taking true branch
883 // If we couldn't find the dominating phi/liveOnEntry in the above loop,
884 // do it now.
885 if (!DefChainEnd
40.1
'DefChainEnd' is null
40.1
'DefChainEnd' is null
40.1
'DefChainEnd' is null
)
41
Taking true branch
886 for (auto *MA : def_chain(const_cast<MemoryAccess *>(Target)))
887 DefChainEnd = MA;
888 assert(DefChainEnd && "Failed to find dominating phi/liveOnEntry")((void)0);
889
890 // If any of the terminated paths don't dominate the phi we'll try to
891 // optimize, we need to figure out what they are and quit.
892 const BasicBlock *ChainBB = DefChainEnd->getBlock();
42
Called C++ object pointer is null
893 for (const TerminatedPath &TP : TerminatedPaths) {
894 // Because we know that DefChainEnd is as "high" as we can go, we
895 // don't need local dominance checks; BB dominance is sufficient.
896 if (DT.dominates(ChainBB, TP.Clobber->getBlock()))
897 Clobbers.push_back(TP);
898 }
899 }
900
901 // If we have clobbers in the def chain, find the one closest to Current
902 // and quit.
903 if (!Clobbers.empty()) {
904 MoveDominatedPathToEnd(Clobbers);
905 TerminatedPath Result = Clobbers.pop_back_val();
906 return {Result, std::move(Clobbers)};
907 }
908
909 assert(all_of(NewPaused,((void)0)
910 [&](ListIndex I) { return Paths[I].Last == DefChainEnd; }))((void)0);
911
912 // Because liveOnEntry is a clobber, this must be a phi.
913 auto *DefChainPhi = cast<MemoryPhi>(DefChainEnd);
914
915 PriorPathsSize = Paths.size();
916 PausedSearches.clear();
917 for (ListIndex I : NewPaused)
918 addSearches(DefChainPhi, PausedSearches, I);
919 NewPaused.clear();
920
921 Current = DefChainPhi;
922 }
923 }
924
925 void verifyOptResult(const OptznResult &R) const {
926 assert(all_of(R.OtherClobbers, [&](const TerminatedPath &P) {((void)0)
927 return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber);((void)0)
928 }))((void)0);
929 }
930
931 void resetPhiOptznState() {
932 Paths.clear();
933 VisitedPhis.clear();
934 PerformedPhiTranslation = false;
935 }
936
937public:
938 ClobberWalker(const MemorySSA &MSSA, AliasAnalysisType &AA, DominatorTree &DT)
939 : MSSA(MSSA), AA(AA), DT(DT) {}
940
941 AliasAnalysisType *getAA() { return &AA; }
942 /// Finds the nearest clobber for the given query, optimizing phis if
943 /// possible.
944 MemoryAccess *findClobber(MemoryAccess *Start, UpwardsMemoryQuery &Q,
945 unsigned &UpWalkLimit) {
946 Query = &Q;
947 UpwardWalkLimit = &UpWalkLimit;
948 // Starting limit must be > 0.
949 if (!UpWalkLimit)
6
Assuming 'UpWalkLimit' is not equal to 0
7
Taking false branch
950 UpWalkLimit++;
951
952 MemoryAccess *Current = Start;
953 // This walker pretends uses don't exist. If we're handed one, silently grab
954 // its def. (This has the nice side-effect of ensuring we never cache uses)
955 if (auto *MU
8.1
'MU' is null
8.1
'MU' is null
8.1
'MU' is null
= dyn_cast<MemoryUse>(Start))
8
Assuming 'Start' is not a 'MemoryUse'
9
Taking false branch
956 Current = MU->getDefiningAccess();
957
958 DefPath FirstDesc(Q.StartingLoc, Current, Current, None);
959 // Fast path for the overly-common case (no crazy phi optimization
960 // necessary)
961 UpwardsWalkResult WalkResult = walkToPhiOrClobber(FirstDesc);
962 MemoryAccess *Result;
963 if (WalkResult.IsKnownClobber
9.1
Field 'IsKnownClobber' is false
9.1
Field 'IsKnownClobber' is false
9.1
Field 'IsKnownClobber' is false
) {
10
Taking false branch
964 Result = WalkResult.Result;
965 Q.AR = WalkResult.AR;
966 } else {
967 OptznResult OptRes = tryOptimizePhi(cast<MemoryPhi>(FirstDesc.Last),
11
Field 'Last' is a 'MemoryPhi'
12
Calling 'ClobberWalker::tryOptimizePhi'
968 Current, Q.StartingLoc);
969 verifyOptResult(OptRes);
970 resetPhiOptznState();
971 Result = OptRes.PrimaryClobber.Clobber;
972 }
973
974#ifdef EXPENSIVE_CHECKS
975 if (!Q.SkipSelfAccess && *UpwardWalkLimit > 0)
976 checkClobberSanity(Current, Result, Q.StartingLoc, MSSA, Q, AA);
977#endif
978 return Result;
979 }
980};
981
982struct RenamePassData {
983 DomTreeNode *DTN;
984 DomTreeNode::const_iterator ChildIt;
985 MemoryAccess *IncomingVal;
986
987 RenamePassData(DomTreeNode *D, DomTreeNode::const_iterator It,
988 MemoryAccess *M)
989 : DTN(D), ChildIt(It), IncomingVal(M) {}
990
991 void swap(RenamePassData &RHS) {
992 std::swap(DTN, RHS.DTN);
993 std::swap(ChildIt, RHS.ChildIt);
994 std::swap(IncomingVal, RHS.IncomingVal);
995 }
996};
997
998} // end anonymous namespace
999
1000namespace llvm {
1001
1002template <class AliasAnalysisType> class MemorySSA::ClobberWalkerBase {
1003 ClobberWalker<AliasAnalysisType> Walker;
1004 MemorySSA *MSSA;
1005
1006public:
1007 ClobberWalkerBase(MemorySSA *M, AliasAnalysisType *A, DominatorTree *D)
1008 : Walker(*M, *A, *D), MSSA(M) {}
1009
1010 MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *,
1011 const MemoryLocation &,
1012 unsigned &);
1013 // Third argument (bool), defines whether the clobber search should skip the
1014 // original queried access. If true, there will be a follow-up query searching
1015 // for a clobber access past "self". Note that the Optimized access is not
1016 // updated if a new clobber is found by this SkipSelf search. If this
1017 // additional query becomes heavily used we may decide to cache the result.
1018 // Walker instantiations will decide how to set the SkipSelf bool.
1019 MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *, unsigned &, bool);
1020};
1021
1022/// A MemorySSAWalker that does AA walks to disambiguate accesses. It no
1023/// longer does caching on its own, but the name has been retained for the
1024/// moment.
1025template <class AliasAnalysisType>
1026class MemorySSA::CachingWalker final : public MemorySSAWalker {
1027 ClobberWalkerBase<AliasAnalysisType> *Walker;
1028
1029public:
1030 CachingWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
1031 : MemorySSAWalker(M), Walker(W) {}
1032 ~CachingWalker() override = default;
1033
1034 using MemorySSAWalker::getClobberingMemoryAccess;
1035
1036 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
1037 return Walker->getClobberingMemoryAccessBase(MA, UWL, false);
1038 }
1039 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1040 const MemoryLocation &Loc,
1041 unsigned &UWL) {
1042 return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
1043 }
1044
1045 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
1046 unsigned UpwardWalkLimit = MaxCheckLimit;
1047 return getClobberingMemoryAccess(MA, UpwardWalkLimit);
1048 }
1049 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1050 const MemoryLocation &Loc) override {
1051 unsigned UpwardWalkLimit = MaxCheckLimit;
1052 return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
1053 }
1054
1055 void invalidateInfo(MemoryAccess *MA) override {
1056 if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1057 MUD->resetOptimized();
1058 }
1059};
1060
1061template <class AliasAnalysisType>
1062class MemorySSA::SkipSelfWalker final : public MemorySSAWalker {
1063 ClobberWalkerBase<AliasAnalysisType> *Walker;
1064
1065public:
1066 SkipSelfWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
1067 : MemorySSAWalker(M), Walker(W) {}
1068 ~SkipSelfWalker() override = default;
1069
1070 using MemorySSAWalker::getClobberingMemoryAccess;
1071
1072 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
1073 return Walker->getClobberingMemoryAccessBase(MA, UWL, true);
1074 }
1075 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1076 const MemoryLocation &Loc,
1077 unsigned &UWL) {
1078 return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
2
Calling 'ClobberWalkerBase::getClobberingMemoryAccessBase'
1079 }
1080
1081 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
1082 unsigned UpwardWalkLimit = MaxCheckLimit;
1083 return getClobberingMemoryAccess(MA, UpwardWalkLimit);
1084 }
1085 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1086 const MemoryLocation &Loc) override {
1087 unsigned UpwardWalkLimit = MaxCheckLimit;
1088 return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
1
Calling 'SkipSelfWalker::getClobberingMemoryAccess'
1089 }
1090
1091 void invalidateInfo(MemoryAccess *MA) override {
1092 if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1093 MUD->resetOptimized();
1094 }
1095};
1096
1097} // end namespace llvm
1098
1099void MemorySSA::renameSuccessorPhis(BasicBlock *BB, MemoryAccess *IncomingVal,
1100 bool RenameAllUses) {
1101 // Pass through values to our successors
1102 for (const BasicBlock *S : successors(BB)) {
1103 auto It = PerBlockAccesses.find(S);
1104 // Rename the phi nodes in our successor block
1105 if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1106 continue;
1107 AccessList *Accesses = It->second.get();
1108 auto *Phi = cast<MemoryPhi>(&Accesses->front());
1109 if (RenameAllUses) {
1110 bool ReplacementDone = false;
1111 for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I)
1112 if (Phi->getIncomingBlock(I) == BB) {
1113 Phi->setIncomingValue(I, IncomingVal);
1114 ReplacementDone = true;
1115 }
1116 (void) ReplacementDone;
1117 assert(ReplacementDone && "Incomplete phi during partial rename")((void)0);
1118 } else
1119 Phi->addIncoming(IncomingVal, BB);
1120 }
1121}
1122
1123/// Rename a single basic block into MemorySSA form.
1124/// Uses the standard SSA renaming algorithm.
1125/// \returns The new incoming value.
1126MemoryAccess *MemorySSA::renameBlock(BasicBlock *BB, MemoryAccess *IncomingVal,
1127 bool RenameAllUses) {
1128 auto It = PerBlockAccesses.find(BB);
1129 // Skip most processing if the list is empty.
1130 if (It != PerBlockAccesses.end()) {
1131 AccessList *Accesses = It->second.get();
1132 for (MemoryAccess &L : *Accesses) {
1133 if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&L)) {
1134 if (MUD->getDefiningAccess() == nullptr || RenameAllUses)
1135 MUD->setDefiningAccess(IncomingVal);
1136 if (isa<MemoryDef>(&L))
1137 IncomingVal = &L;
1138 } else {
1139 IncomingVal = &L;
1140 }
1141 }
1142 }
1143 return IncomingVal;
1144}
1145
1146/// This is the standard SSA renaming algorithm.
1147///
1148/// We walk the dominator tree in preorder, renaming accesses, and then filling
1149/// in phi nodes in our successors.
1150void MemorySSA::renamePass(DomTreeNode *Root, MemoryAccess *IncomingVal,
1151 SmallPtrSetImpl<BasicBlock *> &Visited,
1152 bool SkipVisited, bool RenameAllUses) {
1153 assert(Root && "Trying to rename accesses in an unreachable block")((void)0);
1154
1155 SmallVector<RenamePassData, 32> WorkStack;
1156 // Skip everything if we already renamed this block and we are skipping.
1157 // Note: You can't sink this into the if, because we need it to occur
1158 // regardless of whether we skip blocks or not.
1159 bool AlreadyVisited = !Visited.insert(Root->getBlock()).second;
1160 if (SkipVisited && AlreadyVisited)
1161 return;
1162
1163 IncomingVal = renameBlock(Root->getBlock(), IncomingVal, RenameAllUses);
1164 renameSuccessorPhis(Root->getBlock(), IncomingVal, RenameAllUses);
1165 WorkStack.push_back({Root, Root->begin(), IncomingVal});
1166
1167 while (!WorkStack.empty()) {
1168 DomTreeNode *Node = WorkStack.back().DTN;
1169 DomTreeNode::const_iterator ChildIt = WorkStack.back().ChildIt;
1170 IncomingVal = WorkStack.back().IncomingVal;
1171
1172 if (ChildIt == Node->end()) {
1173 WorkStack.pop_back();
1174 } else {
1175 DomTreeNode *Child = *ChildIt;
1176 ++WorkStack.back().ChildIt;
1177 BasicBlock *BB = Child->getBlock();
1178 // Note: You can't sink this into the if, because we need it to occur
1179 // regardless of whether we skip blocks or not.
1180 AlreadyVisited = !Visited.insert(BB).second;
1181 if (SkipVisited && AlreadyVisited) {
1182 // We already visited this during our renaming, which can happen when
1183 // being asked to rename multiple blocks. Figure out the incoming val,
1184 // which is the last def.
1185 // Incoming value can only change if there is a block def, and in that
1186 // case, it's the last block def in the list.
1187 if (auto *BlockDefs = getWritableBlockDefs(BB))
1188 IncomingVal = &*BlockDefs->rbegin();
1189 } else
1190 IncomingVal = renameBlock(BB, IncomingVal, RenameAllUses);
1191 renameSuccessorPhis(BB, IncomingVal, RenameAllUses);
1192 WorkStack.push_back({Child, Child->begin(), IncomingVal});
1193 }
1194 }
1195}
1196
1197/// This handles unreachable block accesses by deleting phi nodes in
1198/// unreachable blocks, and marking all other unreachable MemoryAccess's as
1199/// being uses of the live on entry definition.
1200void MemorySSA::markUnreachableAsLiveOnEntry(BasicBlock *BB) {
1201 assert(!DT->isReachableFromEntry(BB) &&((void)0)
1202 "Reachable block found while handling unreachable blocks")((void)0);
1203
1204 // Make sure phi nodes in our reachable successors end up with a
1205 // LiveOnEntryDef for our incoming edge, even though our block is forward
1206 // unreachable. We could just disconnect these blocks from the CFG fully,
1207 // but we do not right now.
1208 for (const BasicBlock *S : successors(BB)) {
1209 if (!DT->isReachableFromEntry(S))
1210 continue;
1211 auto It = PerBlockAccesses.find(S);
1212 // Rename the phi nodes in our successor block
1213 if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1214 continue;
1215 AccessList *Accesses = It->second.get();
1216 auto *Phi = cast<MemoryPhi>(&Accesses->front());
1217 Phi->addIncoming(LiveOnEntryDef.get(), BB);
1218 }
1219
1220 auto It = PerBlockAccesses.find(BB);
1221 if (It == PerBlockAccesses.end())
1222 return;
1223
1224 auto &Accesses = It->second;
1225 for (auto AI = Accesses->begin(), AE = Accesses->end(); AI != AE;) {
1226 auto Next = std::next(AI);
1227 // If we have a phi, just remove it. We are going to replace all
1228 // users with live on entry.
1229 if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(AI))
1230 UseOrDef->setDefiningAccess(LiveOnEntryDef.get());
1231 else
1232 Accesses->erase(AI);
1233 AI = Next;
1234 }
1235}
1236
1237MemorySSA::MemorySSA(Function &Func, AliasAnalysis *AA, DominatorTree *DT)
1238 : AA(nullptr), DT(DT), F(Func), LiveOnEntryDef(nullptr), Walker(nullptr),
1239 SkipWalker(nullptr), NextID(0) {
1240 // Build MemorySSA using a batch alias analysis. This reuses the internal
1241 // state that AA collects during an alias()/getModRefInfo() call. This is
1242 // safe because there are no CFG changes while building MemorySSA and can
1243 // significantly reduce the time spent by the compiler in AA, because we will
1244 // make queries about all the instructions in the Function.
1245 assert(AA && "No alias analysis?")((void)0);
1246 BatchAAResults BatchAA(*AA);
1247 buildMemorySSA(BatchAA);
1248 // Intentionally leave AA to nullptr while building so we don't accidently
1249 // use non-batch AliasAnalysis.
1250 this->AA = AA;
1251 // Also create the walker here.
1252 getWalker();
1253}
1254
1255MemorySSA::~MemorySSA() {
1256 // Drop all our references
1257 for (const auto &Pair : PerBlockAccesses)
1258 for (MemoryAccess &MA : *Pair.second)
1259 MA.dropAllReferences();
1260}
1261
1262MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) {
1263 auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr));
1264
1265 if (Res.second)
1266 Res.first->second = std::make_unique<AccessList>();
1267 return Res.first->second.get();
1268}
1269
1270MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) {
1271 auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr));
1272
1273 if (Res.second)
1274 Res.first->second = std::make_unique<DefsList>();
1275 return Res.first->second.get();
1276}
1277
1278namespace llvm {
1279
1280/// This class is a batch walker of all MemoryUse's in the program, and points
1281/// their defining access at the thing that actually clobbers them. Because it
1282/// is a batch walker that touches everything, it does not operate like the
1283/// other walkers. This walker is basically performing a top-down SSA renaming
1284/// pass, where the version stack is used as the cache. This enables it to be
1285/// significantly more time and memory efficient than using the regular walker,
1286/// which is walking bottom-up.
1287class MemorySSA::OptimizeUses {
1288public:
1289 OptimizeUses(MemorySSA *MSSA, CachingWalker<BatchAAResults> *Walker,
1290 BatchAAResults *BAA, DominatorTree *DT)
1291 : MSSA(MSSA), Walker(Walker), AA(BAA), DT(DT) {}
1292
1293 void optimizeUses();
1294
1295private:
1296 /// This represents where a given memorylocation is in the stack.
1297 struct MemlocStackInfo {
1298 // This essentially is keeping track of versions of the stack. Whenever
1299 // the stack changes due to pushes or pops, these versions increase.
1300 unsigned long StackEpoch;
1301 unsigned long PopEpoch;
1302 // This is the lower bound of places on the stack to check. It is equal to
1303 // the place the last stack walk ended.
1304 // Note: Correctness depends on this being initialized to 0, which densemap
1305 // does
1306 unsigned long LowerBound;
1307 const BasicBlock *LowerBoundBlock;
1308 // This is where the last walk for this memory location ended.
1309 unsigned long LastKill;
1310 bool LastKillValid;
1311 Optional<AliasResult> AR;
1312 };
1313
1314 void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &,
1315 SmallVectorImpl<MemoryAccess *> &,
1316 DenseMap<MemoryLocOrCall, MemlocStackInfo> &);
1317
1318 MemorySSA *MSSA;
1319 CachingWalker<BatchAAResults> *Walker;
1320 BatchAAResults *AA;
1321 DominatorTree *DT;
1322};
1323
1324} // end namespace llvm
1325
1326/// Optimize the uses in a given block This is basically the SSA renaming
1327/// algorithm, with one caveat: We are able to use a single stack for all
1328/// MemoryUses. This is because the set of *possible* reaching MemoryDefs is
1329/// the same for every MemoryUse. The *actual* clobbering MemoryDef is just
1330/// going to be some position in that stack of possible ones.
1331///
1332/// We track the stack positions that each MemoryLocation needs
1333/// to check, and last ended at. This is because we only want to check the
1334/// things that changed since last time. The same MemoryLocation should
1335/// get clobbered by the same store (getModRefInfo does not use invariantness or
1336/// things like this, and if they start, we can modify MemoryLocOrCall to
1337/// include relevant data)
1338void MemorySSA::OptimizeUses::optimizeUsesInBlock(
1339 const BasicBlock *BB, unsigned long &StackEpoch, unsigned long &PopEpoch,
1340 SmallVectorImpl<MemoryAccess *> &VersionStack,
1341 DenseMap<MemoryLocOrCall, MemlocStackInfo> &LocStackInfo) {
1342
1343 /// If no accesses, nothing to do.
1344 MemorySSA::AccessList *Accesses = MSSA->getWritableBlockAccesses(BB);
1345 if (Accesses == nullptr)
1346 return;
1347
1348 // Pop everything that doesn't dominate the current block off the stack,
1349 // increment the PopEpoch to account for this.
1350 while (true) {
1351 assert(((void)0)
1352 !VersionStack.empty() &&((void)0)
1353 "Version stack should have liveOnEntry sentinel dominating everything")((void)0);
1354 BasicBlock *BackBlock = VersionStack.back()->getBlock();
1355 if (DT->dominates(BackBlock, BB))
1356 break;
1357 while (VersionStack.back()->getBlock() == BackBlock)
1358 VersionStack.pop_back();
1359 ++PopEpoch;
1360 }
1361
1362 for (MemoryAccess &MA : *Accesses) {
1363 auto *MU = dyn_cast<MemoryUse>(&MA);
1364 if (!MU) {
1365 VersionStack.push_back(&MA);
1366 ++StackEpoch;
1367 continue;
1368 }
1369
1370 if (isUseTriviallyOptimizableToLiveOnEntry(*AA, MU->getMemoryInst())) {
1371 MU->setDefiningAccess(MSSA->getLiveOnEntryDef(), true, None);
1372 continue;
1373 }
1374
1375 MemoryLocOrCall UseMLOC(MU);
1376 auto &LocInfo = LocStackInfo[UseMLOC];
1377 // If the pop epoch changed, it means we've removed stuff from top of
1378 // stack due to changing blocks. We may have to reset the lower bound or
1379 // last kill info.
1380 if (LocInfo.PopEpoch != PopEpoch) {
1381 LocInfo.PopEpoch = PopEpoch;
1382 LocInfo.StackEpoch = StackEpoch;
1383 // If the lower bound was in something that no longer dominates us, we
1384 // have to reset it.
1385 // We can't simply track stack size, because the stack may have had
1386 // pushes/pops in the meantime.
1387 // XXX: This is non-optimal, but only is slower cases with heavily
1388 // branching dominator trees. To get the optimal number of queries would
1389 // be to make lowerbound and lastkill a per-loc stack, and pop it until
1390 // the top of that stack dominates us. This does not seem worth it ATM.
1391 // A much cheaper optimization would be to always explore the deepest
1392 // branch of the dominator tree first. This will guarantee this resets on
1393 // the smallest set of blocks.
1394 if (LocInfo.LowerBoundBlock && LocInfo.LowerBoundBlock != BB &&
1395 !DT->dominates(LocInfo.LowerBoundBlock, BB)) {
1396 // Reset the lower bound of things to check.
1397 // TODO: Some day we should be able to reset to last kill, rather than
1398 // 0.
1399 LocInfo.LowerBound = 0;
1400 LocInfo.LowerBoundBlock = VersionStack[0]->getBlock();
1401 LocInfo.LastKillValid = false;
1402 }
1403 } else if (LocInfo.StackEpoch != StackEpoch) {
1404 // If all that has changed is the StackEpoch, we only have to check the
1405 // new things on the stack, because we've checked everything before. In
1406 // this case, the lower bound of things to check remains the same.
1407 LocInfo.PopEpoch = PopEpoch;
1408 LocInfo.StackEpoch = StackEpoch;
1409 }
1410 if (!LocInfo.LastKillValid) {
1411 LocInfo.LastKill = VersionStack.size() - 1;
1412 LocInfo.LastKillValid = true;
1413 LocInfo.AR = AliasResult::MayAlias;
1414 }
1415
1416 // At this point, we should have corrected last kill and LowerBound to be
1417 // in bounds.
1418 assert(LocInfo.LowerBound < VersionStack.size() &&((void)0)
1419 "Lower bound out of range")((void)0);
1420 assert(LocInfo.LastKill < VersionStack.size() &&((void)0)
1421 "Last kill info out of range")((void)0);
1422 // In any case, the new upper bound is the top of the stack.
1423 unsigned long UpperBound = VersionStack.size() - 1;
1424
1425 if (UpperBound - LocInfo.LowerBound > MaxCheckLimit) {
1426 LLVM_DEBUG(dbgs() << "MemorySSA skipping optimization of " << *MU << " ("do { } while (false)
1427 << *(MU->getMemoryInst()) << ")"do { } while (false)
1428 << " because there are "do { } while (false)
1429 << UpperBound - LocInfo.LowerBounddo { } while (false)
1430 << " stores to disambiguate\n")do { } while (false);
1431 // Because we did not walk, LastKill is no longer valid, as this may
1432 // have been a kill.
1433 LocInfo.LastKillValid = false;
1434 continue;
1435 }
1436 bool FoundClobberResult = false;
1437 unsigned UpwardWalkLimit = MaxCheckLimit;
1438 while (UpperBound > LocInfo.LowerBound) {
1439 if (isa<MemoryPhi>(VersionStack[UpperBound])) {
1440 // For phis, use the walker, see where we ended up, go there
1441 MemoryAccess *Result =
1442 Walker->getClobberingMemoryAccess(MU, UpwardWalkLimit);
1443 // We are guaranteed to find it or something is wrong
1444 while (VersionStack[UpperBound] != Result) {
1445 assert(UpperBound != 0)((void)0);
1446 --UpperBound;
1447 }
1448 FoundClobberResult = true;
1449 break;
1450 }
1451
1452 MemoryDef *MD = cast<MemoryDef>(VersionStack[UpperBound]);
1453 ClobberAlias CA = instructionClobbersQuery(MD, MU, UseMLOC, *AA);
1454 if (CA.IsClobber) {
1455 FoundClobberResult = true;
1456 LocInfo.AR = CA.AR;
1457 break;
1458 }
1459 --UpperBound;
1460 }
1461
1462 // Note: Phis always have AliasResult AR set to MayAlias ATM.
1463
1464 // At the end of this loop, UpperBound is either a clobber, or lower bound
1465 // PHI walking may cause it to be < LowerBound, and in fact, < LastKill.
1466 if (FoundClobberResult || UpperBound < LocInfo.LastKill) {
1467 // We were last killed now by where we got to
1468 if (MSSA->isLiveOnEntryDef(VersionStack[UpperBound]))
1469 LocInfo.AR = None;
1470 MU->setDefiningAccess(VersionStack[UpperBound], true, LocInfo.AR);
1471 LocInfo.LastKill = UpperBound;
1472 } else {
1473 // Otherwise, we checked all the new ones, and now we know we can get to
1474 // LastKill.
1475 MU->setDefiningAccess(VersionStack[LocInfo.LastKill], true, LocInfo.AR);
1476 }
1477 LocInfo.LowerBound = VersionStack.size() - 1;
1478 LocInfo.LowerBoundBlock = BB;
1479 }
1480}
1481
1482/// Optimize uses to point to their actual clobbering definitions.
1483void MemorySSA::OptimizeUses::optimizeUses() {
1484 SmallVector<MemoryAccess *, 16> VersionStack;
1485 DenseMap<MemoryLocOrCall, MemlocStackInfo> LocStackInfo;
1486 VersionStack.push_back(MSSA->getLiveOnEntryDef());
1487
1488 unsigned long StackEpoch = 1;
1489 unsigned long PopEpoch = 1;
1490 // We perform a non-recursive top-down dominator tree walk.
1491 for (const auto *DomNode : depth_first(DT->getRootNode()))
1492 optimizeUsesInBlock(DomNode->getBlock(), StackEpoch, PopEpoch, VersionStack,
1493 LocStackInfo);
1494}
1495
1496void MemorySSA::placePHINodes(
1497 const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks) {
1498 // Determine where our MemoryPhi's should go
1499 ForwardIDFCalculator IDFs(*DT);
1500 IDFs.setDefiningBlocks(DefiningBlocks);
1501 SmallVector<BasicBlock *, 32> IDFBlocks;
1502 IDFs.calculate(IDFBlocks);
1503
1504 // Now place MemoryPhi nodes.
1505 for (auto &BB : IDFBlocks)
1506 createMemoryPhi(BB);
1507}
1508
1509void MemorySSA::buildMemorySSA(BatchAAResults &BAA) {
1510 // We create an access to represent "live on entry", for things like
1511 // arguments or users of globals, where the memory they use is defined before
1512 // the beginning of the function. We do not actually insert it into the IR.
1513 // We do not define a live on exit for the immediate uses, and thus our
1514 // semantics do *not* imply that something with no immediate uses can simply
1515 // be removed.
1516 BasicBlock &StartingPoint = F.getEntryBlock();
1517 LiveOnEntryDef.reset(new MemoryDef(F.getContext(), nullptr, nullptr,
1518 &StartingPoint, NextID++));
1519
1520 // We maintain lists of memory accesses per-block, trading memory for time. We
1521 // could just look up the memory access for every possible instruction in the
1522 // stream.
1523 SmallPtrSet<BasicBlock *, 32> DefiningBlocks;
1524 // Go through each block, figure out where defs occur, and chain together all
1525 // the accesses.
1526 for (BasicBlock &B : F) {
1527 bool InsertIntoDef = false;
1528 AccessList *Accesses = nullptr;
1529 DefsList *Defs = nullptr;
1530 for (Instruction &I : B) {
1531 MemoryUseOrDef *MUD = createNewAccess(&I, &BAA);
1532 if (!MUD)
1533 continue;
1534
1535 if (!Accesses)
1536 Accesses = getOrCreateAccessList(&B);
1537 Accesses->push_back(MUD);
1538 if (isa<MemoryDef>(MUD)) {
1539 InsertIntoDef = true;
1540 if (!Defs)
1541 Defs = getOrCreateDefsList(&B);
1542 Defs->push_back(*MUD);
1543 }
1544 }
1545 if (InsertIntoDef)
1546 DefiningBlocks.insert(&B);
1547 }
1548 placePHINodes(DefiningBlocks);
1549
1550 // Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
1551 // filled in with all blocks.
1552 SmallPtrSet<BasicBlock *, 16> Visited;
1553 renamePass(DT->getRootNode(), LiveOnEntryDef.get(), Visited);
1554
1555 ClobberWalkerBase<BatchAAResults> WalkerBase(this, &BAA, DT);
1556 CachingWalker<BatchAAResults> WalkerLocal(this, &WalkerBase);
1557 OptimizeUses(this, &WalkerLocal, &BAA, DT).optimizeUses();
1558
1559 // Mark the uses in unreachable blocks as live on entry, so that they go
1560 // somewhere.
1561 for (auto &BB : F)
1562 if (!Visited.count(&BB))
1563 markUnreachableAsLiveOnEntry(&BB);
1564}
1565
1566MemorySSAWalker *MemorySSA::getWalker() { return getWalkerImpl(); }
1567
1568MemorySSA::CachingWalker<AliasAnalysis> *MemorySSA::getWalkerImpl() {
1569 if (Walker)
1570 return Walker.get();
1571
1572 if (!WalkerBase)
1573 WalkerBase =
1574 std::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);
1575
1576 Walker =
1577 std::make_unique<CachingWalker<AliasAnalysis>>(this, WalkerBase.get());
1578 return Walker.get();
1579}
1580
1581MemorySSAWalker *MemorySSA::getSkipSelfWalker() {
1582 if (SkipWalker)
1583 return SkipWalker.get();
1584
1585 if (!WalkerBase)
1586 WalkerBase =
1587 std::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);
1588
1589 SkipWalker =
1590 std::make_unique<SkipSelfWalker<AliasAnalysis>>(this, WalkerBase.get());
1591 return SkipWalker.get();
1592 }
1593
1594
1595// This is a helper function used by the creation routines. It places NewAccess
1596// into the access and defs lists for a given basic block, at the given
1597// insertion point.
1598void MemorySSA::insertIntoListsForBlock(MemoryAccess *NewAccess,
1599 const BasicBlock *BB,
1600 InsertionPlace Point) {
1601 auto *Accesses = getOrCreateAccessList(BB);
1602 if (Point == Beginning) {
1603 // If it's a phi node, it goes first, otherwise, it goes after any phi
1604 // nodes.
1605 if (isa<MemoryPhi>(NewAccess)) {
1606 Accesses->push_front(NewAccess);
1607 auto *Defs = getOrCreateDefsList(BB);
1608 Defs->push_front(*NewAccess);
1609 } else {
1610 auto AI = find_if_not(
1611 *Accesses, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1612 Accesses->insert(AI, NewAccess);
1613 if (!isa<MemoryUse>(NewAccess)) {
1614 auto *Defs = getOrCreateDefsList(BB);
1615 auto DI = find_if_not(
1616 *Defs, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1617 Defs->insert(DI, *NewAccess);
1618 }
1619 }
1620 } else {
1621 Accesses->push_back(NewAccess);
1622 if (!isa<MemoryUse>(NewAccess)) {
1623 auto *Defs = getOrCreateDefsList(BB);
1624 Defs->push_back(*NewAccess);
1625 }
1626 }
1627 BlockNumberingValid.erase(BB);
1628}
1629
1630void MemorySSA::insertIntoListsBefore(MemoryAccess *What, const BasicBlock *BB,
1631 AccessList::iterator InsertPt) {
1632 auto *Accesses = getWritableBlockAccesses(BB);
1633 bool WasEnd = InsertPt == Accesses->end();
1634 Accesses->insert(AccessList::iterator(InsertPt), What);
1635 if (!isa<MemoryUse>(What)) {
1636 auto *Defs = getOrCreateDefsList(BB);
1637 // If we got asked to insert at the end, we have an easy job, just shove it
1638 // at the end. If we got asked to insert before an existing def, we also get
1639 // an iterator. If we got asked to insert before a use, we have to hunt for
1640 // the next def.
1641 if (WasEnd) {
1642 Defs->push_back(*What);
1643 } else if (isa<MemoryDef>(InsertPt)) {
1644 Defs->insert(InsertPt->getDefsIterator(), *What);
1645 } else {
1646 while (InsertPt != Accesses->end() && !isa<MemoryDef>(InsertPt))
1647 ++InsertPt;
1648 // Either we found a def, or we are inserting at the end
1649 if (InsertPt == Accesses->end())
1650 Defs->push_back(*What);
1651 else
1652 Defs->insert(InsertPt->getDefsIterator(), *What);
1653 }
1654 }
1655 BlockNumberingValid.erase(BB);
1656}
1657
1658void MemorySSA::prepareForMoveTo(MemoryAccess *What, BasicBlock *BB) {
1659 // Keep it in the lookup tables, remove from the lists
1660 removeFromLists(What, false);
1661
1662 // Note that moving should implicitly invalidate the optimized state of a
1663 // MemoryUse (and Phis can't be optimized). However, it doesn't do so for a
1664 // MemoryDef.
1665 if (auto *MD = dyn_cast<MemoryDef>(What))
1666 MD->resetOptimized();
1667 What->setBlock(BB);
1668}
1669
1670// Move What before Where in the IR. The end result is that What will belong to
1671// the right lists and have the right Block set, but will not otherwise be
1672// correct. It will not have the right defining access, and if it is a def,
1673// things below it will not properly be updated.
1674void MemorySSA::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
1675 AccessList::iterator Where) {
1676 prepareForMoveTo(What, BB);
1677 insertIntoListsBefore(What, BB, Where);
1678}
1679
1680void MemorySSA::moveTo(MemoryAccess *What, BasicBlock *BB,
1681 InsertionPlace Point) {
1682 if (isa<MemoryPhi>(What)) {
1683 assert(Point == Beginning &&((void)0)
1684 "Can only move a Phi at the beginning of the block")((void)0);
1685 // Update lookup table entry
1686 ValueToMemoryAccess.erase(What->getBlock());
1687 bool Inserted = ValueToMemoryAccess.insert({BB, What}).second;
1688 (void)Inserted;
1689 assert(Inserted && "Cannot move a Phi to a block that already has one")((void)0);
1690 }
1691
1692 prepareForMoveTo(What, BB);
1693 insertIntoListsForBlock(What, BB, Point);
1694}
1695
1696MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) {
1697 assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB")((void)0);
1698 MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
1699 // Phi's always are placed at the front of the block.
1700 insertIntoListsForBlock(Phi, BB, Beginning);
1701 ValueToMemoryAccess[BB] = Phi;
1702 return Phi;
1703}
1704
1705MemoryUseOrDef *MemorySSA::createDefinedAccess(Instruction *I,
1706 MemoryAccess *Definition,
1707 const MemoryUseOrDef *Template,
1708 bool CreationMustSucceed) {
1709 assert(!isa<PHINode>(I) && "Cannot create a defined access for a PHI")((void)0);
1710 MemoryUseOrDef *NewAccess = createNewAccess(I, AA, Template);
1711 if (CreationMustSucceed)
1712 assert(NewAccess != nullptr && "Tried to create a memory access for a "((void)0)
1713 "non-memory touching instruction")((void)0);
1714 if (NewAccess) {
1715 assert((!Definition || !isa<MemoryUse>(Definition)) &&((void)0)
1716 "A use cannot be a defining access")((void)0);
1717 NewAccess->setDefiningAccess(Definition);
1718 }
1719 return NewAccess;
1720}
1721
1722// Return true if the instruction has ordering constraints.
1723// Note specifically that this only considers stores and loads
1724// because others are still considered ModRef by getModRefInfo.
1725static inline bool isOrdered(const Instruction *I) {
1726 if (auto *SI = dyn_cast<StoreInst>(I)) {
1727 if (!SI->isUnordered())
1728 return true;
1729 } else if (auto *LI = dyn_cast<LoadInst>(I)) {
1730 if (!LI->isUnordered())
1731 return true;
1732 }
1733 return false;
1734}
1735
1736/// Helper function to create new memory accesses
1737template <typename AliasAnalysisType>
1738MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I,
1739 AliasAnalysisType *AAP,
1740 const MemoryUseOrDef *Template) {
1741 // The assume intrinsic has a control dependency which we model by claiming
1742 // that it writes arbitrarily. Debuginfo intrinsics may be considered
1743 // clobbers when we have a nonstandard AA pipeline. Ignore these fake memory
1744 // dependencies here.
1745 // FIXME: Replace this special casing with a more accurate modelling of
1746 // assume's control dependency.
1747 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
1748 switch (II->getIntrinsicID()) {
1749 default:
1750 break;
1751 case Intrinsic::assume:
1752 case Intrinsic::experimental_noalias_scope_decl:
1753 return nullptr;
1754 }
1755 }
1756
1757 // Using a nonstandard AA pipelines might leave us with unexpected modref
1758 // results for I, so add a check to not model instructions that may not read
1759 // from or write to memory. This is necessary for correctness.
1760 if (!I->mayReadFromMemory() && !I->mayWriteToMemory())
1761 return nullptr;
1762
1763 bool Def, Use;
1764 if (Template) {
1765 Def = isa<MemoryDef>(Template);
1766 Use = isa<MemoryUse>(Template);
1767#if !defined(NDEBUG1)
1768 ModRefInfo ModRef = AAP->getModRefInfo(I, None);
1769 bool DefCheck, UseCheck;
1770 DefCheck = isModSet(ModRef) || isOrdered(I);
1771 UseCheck = isRefSet(ModRef);
1772 assert(Def == DefCheck && (Def || Use == UseCheck) && "Invalid template")((void)0);
1773#endif
1774 } else {
1775 // Find out what affect this instruction has on memory.
1776 ModRefInfo ModRef = AAP->getModRefInfo(I, None);
1777 // The isOrdered check is used to ensure that volatiles end up as defs
1778 // (atomics end up as ModRef right now anyway). Until we separate the
1779 // ordering chain from the memory chain, this enables people to see at least
1780 // some relative ordering to volatiles. Note that getClobberingMemoryAccess
1781 // will still give an answer that bypasses other volatile loads. TODO:
1782 // Separate memory aliasing and ordering into two different chains so that
1783 // we can precisely represent both "what memory will this read/write/is
1784 // clobbered by" and "what instructions can I move this past".
1785 Def = isModSet(ModRef) || isOrdered(I);
1786 Use = isRefSet(ModRef);
1787 }
1788
1789 // It's possible for an instruction to not modify memory at all. During
1790 // construction, we ignore them.
1791 if (!Def && !Use)
1792 return nullptr;
1793
1794 MemoryUseOrDef *MUD;
1795 if (Def)
1796 MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++);
1797 else
1798 MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent());
1799 ValueToMemoryAccess[I] = MUD;
1800 return MUD;
1801}
1802
1803/// Properly remove \p MA from all of MemorySSA's lookup tables.
1804void MemorySSA::removeFromLookups(MemoryAccess *MA) {
1805 assert(MA->use_empty() &&((void)0)
1806 "Trying to remove memory access that still has uses")((void)0);
1807 BlockNumbering.erase(MA);
1808 if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1809 MUD->setDefiningAccess(nullptr);
1810 // Invalidate our walker's cache if necessary
1811 if (!isa<MemoryUse>(MA))
1812 getWalker()->invalidateInfo(MA);
1813
1814 Value *MemoryInst;
1815 if (const auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1816 MemoryInst = MUD->getMemoryInst();
1817 else
1818 MemoryInst = MA->getBlock();
1819
1820 auto VMA = ValueToMemoryAccess.find(MemoryInst);
1821 if (VMA->second == MA)
1822 ValueToMemoryAccess.erase(VMA);
1823}
1824
1825/// Properly remove \p MA from all of MemorySSA's lists.
1826///
1827/// Because of the way the intrusive list and use lists work, it is important to
1828/// do removal in the right order.
1829/// ShouldDelete defaults to true, and will cause the memory access to also be
1830/// deleted, not just removed.
1831void MemorySSA::removeFromLists(MemoryAccess *MA, bool ShouldDelete) {
1832 BasicBlock *BB = MA->getBlock();
1833 // The access list owns the reference, so we erase it from the non-owning list
1834 // first.
1835 if (!isa<MemoryUse>(MA)) {
1836 auto DefsIt = PerBlockDefs.find(BB);
1837 std::unique_ptr<DefsList> &Defs = DefsIt->second;
1838 Defs->remove(*MA);
1839 if (Defs->empty())
1840 PerBlockDefs.erase(DefsIt);
1841 }
1842
1843 // The erase call here will delete it. If we don't want it deleted, we call
1844 // remove instead.
1845 auto AccessIt = PerBlockAccesses.find(BB);
1846 std::unique_ptr<AccessList> &Accesses = AccessIt->second;
1847 if (ShouldDelete)
1848 Accesses->erase(MA);
1849 else
1850 Accesses->remove(MA);
1851
1852 if (Accesses->empty()) {
1853 PerBlockAccesses.erase(AccessIt);
1854 BlockNumberingValid.erase(BB);
1855 }
1856}
1857
1858void MemorySSA::print(raw_ostream &OS) const {
1859 MemorySSAAnnotatedWriter Writer(this);
1860 F.print(OS, &Writer);
1861}
1862
1863#if !defined(NDEBUG1) || defined(LLVM_ENABLE_DUMP)
1864LLVM_DUMP_METHOD__attribute__((noinline)) void MemorySSA::dump() const { print(dbgs()); }
1865#endif
1866
1867void MemorySSA::verifyMemorySSA() const {
1868 verifyOrderingDominationAndDefUses(F);
1869 verifyDominationNumbers(F);
1870 verifyPrevDefInPhis(F);
1871 // Previously, the verification used to also verify that the clobberingAccess
1872 // cached by MemorySSA is the same as the clobberingAccess found at a later
1873 // query to AA. This does not hold true in general due to the current fragility
1874 // of BasicAA which has arbitrary caps on the things it analyzes before giving
1875 // up. As a result, transformations that are correct, will lead to BasicAA
1876 // returning different Alias answers before and after that transformation.
1877 // Invalidating MemorySSA is not an option, as the results in BasicAA can be so
1878 // random, in the worst case we'd need to rebuild MemorySSA from scratch after
1879 // every transformation, which defeats the purpose of using it. For such an
1880 // example, see test4 added in D51960.
1881}
1882
1883void MemorySSA::verifyPrevDefInPhis(Function &F) const {
1884#if !defined(NDEBUG1) && defined(EXPENSIVE_CHECKS)
1885 for (const BasicBlock &BB : F) {
1886 if (MemoryPhi *Phi = getMemoryAccess(&BB)) {
1887 for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
1888 auto *Pred = Phi->getIncomingBlock(I);
1889 auto *IncAcc = Phi->getIncomingValue(I);
1890 // If Pred has no unreachable predecessors, get last def looking at
1891 // IDoms. If, while walkings IDoms, any of these has an unreachable
1892 // predecessor, then the incoming def can be any access.
1893 if (auto *DTNode = DT->getNode(Pred)) {
1894 while (DTNode) {
1895 if (auto *DefList = getBlockDefs(DTNode->getBlock())) {
1896 auto *LastAcc = &*(--DefList->end());
1897 assert(LastAcc == IncAcc &&((void)0)
1898 "Incorrect incoming access into phi.")((void)0);
1899 break;
1900 }
1901 DTNode = DTNode->getIDom();
1902 }
1903 } else {
1904 // If Pred has unreachable predecessors, but has at least a Def, the
1905 // incoming access can be the last Def in Pred, or it could have been
1906 // optimized to LoE. After an update, though, the LoE may have been
1907 // replaced by another access, so IncAcc may be any access.
1908 // If Pred has unreachable predecessors and no Defs, incoming access
1909 // should be LoE; However, after an update, it may be any access.
1910 }
1911 }
1912 }
1913 }
1914#endif
1915}
1916
1917/// Verify that all of the blocks we believe to have valid domination numbers
1918/// actually have valid domination numbers.
1919void MemorySSA::verifyDominationNumbers(const Function &F) const {
1920#ifndef NDEBUG1
1921 if (BlockNumberingValid.empty())
1922 return;
1923
1924 SmallPtrSet<const BasicBlock *, 16> ValidBlocks = BlockNumberingValid;
1925 for (const BasicBlock &BB : F) {
1926 if (!ValidBlocks.count(&BB))
1927 continue;
1928
1929 ValidBlocks.erase(&BB);
1930
1931 const AccessList *Accesses = getBlockAccesses(&BB);
1932 // It's correct to say an empty block has valid numbering.
1933 if (!Accesses)
1934 continue;
1935
1936 // Block numbering starts at 1.
1937 unsigned long LastNumber = 0;
1938 for (const MemoryAccess &MA : *Accesses) {
1939 auto ThisNumberIter = BlockNumbering.find(&MA);
1940 assert(ThisNumberIter != BlockNumbering.end() &&((void)0)
1941 "MemoryAccess has no domination number in a valid block!")((void)0);
1942
1943 unsigned long ThisNumber = ThisNumberIter->second;
1944 assert(ThisNumber > LastNumber &&((void)0)
1945 "Domination numbers should be strictly increasing!")((void)0);
1946 LastNumber = ThisNumber;
1947 }
1948 }
1949
1950 assert(ValidBlocks.empty() &&((void)0)
1951 "All valid BasicBlocks should exist in F -- dangling pointers?")((void)0);
1952#endif
1953}
1954
1955/// Verify ordering: the order and existence of MemoryAccesses matches the
1956/// order and existence of memory affecting instructions.
1957/// Verify domination: each definition dominates all of its uses.
1958/// Verify def-uses: the immediate use information - walk all the memory
1959/// accesses and verifying that, for each use, it appears in the appropriate
1960/// def's use list
1961void MemorySSA::verifyOrderingDominationAndDefUses(Function &F) const {
1962#if !defined(NDEBUG1)
1963 // Walk all the blocks, comparing what the lookups think and what the access
1964 // lists think, as well as the order in the blocks vs the order in the access
1965 // lists.
1966 SmallVector<MemoryAccess *, 32> ActualAccesses;
1967 SmallVector<MemoryAccess *, 32> ActualDefs;
1968 for (BasicBlock &B : F) {
1969 const AccessList *AL = getBlockAccesses(&B);
1970 const auto *DL = getBlockDefs(&B);
1971 MemoryPhi *Phi = getMemoryAccess(&B);
1972 if (Phi) {
1973 // Verify ordering.
1974 ActualAccesses.push_back(Phi);
1975 ActualDefs.push_back(Phi);
1976 // Verify domination
1977 for (const Use &U : Phi->uses())
1978 assert(dominates(Phi, U) && "Memory PHI does not dominate it's uses")((void)0);
1979#if defined(EXPENSIVE_CHECKS)
1980 // Verify def-uses.
1981 assert(Phi->getNumOperands() == static_cast<unsigned>(std::distance(((void)0)
1982 pred_begin(&B), pred_end(&B))) &&((void)0)
1983 "Incomplete MemoryPhi Node")((void)0);
1984 for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
1985 verifyUseInDefs(Phi->getIncomingValue(I), Phi);
1986 assert(is_contained(predecessors(&B), Phi->getIncomingBlock(I)) &&((void)0)
1987 "Incoming phi block not a block predecessor")((void)0);
1988 }
1989#endif
1990 }
1991
1992 for (Instruction &I : B) {
1993 MemoryUseOrDef *MA = getMemoryAccess(&I);
1994 assert((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&((void)0)
1995 "We have memory affecting instructions "((void)0)
1996 "in this block but they are not in the "((void)0)
1997 "access list or defs list")((void)0);
1998 if (MA) {
1999 // Verify ordering.
2000 ActualAccesses.push_back(MA);
2001 if (MemoryAccess *MD = dyn_cast<MemoryDef>(MA)) {
2002 // Verify ordering.
2003 ActualDefs.push_back(MA);
2004 // Verify domination.
2005 for (const Use &U : MD->uses())
2006 assert(dominates(MD, U) &&((void)0)
2007 "Memory Def does not dominate it's uses")((void)0);
2008 }
2009#if defined(EXPENSIVE_CHECKS)
2010 // Verify def-uses.
2011 verifyUseInDefs(MA->getDefiningAccess(), MA);
2012#endif
2013 }
2014 }
2015 // Either we hit the assert, really have no accesses, or we have both
2016 // accesses and an access list. Same with defs.
2017 if (!AL && !DL)
2018 continue;
2019 // Verify ordering.
2020 assert(AL->size() == ActualAccesses.size() &&((void)0)
2021 "We don't have the same number of accesses in the block as on the "((void)0)
2022 "access list")((void)0);
2023 assert((DL || ActualDefs.size() == 0) &&((void)0)
2024 "Either we should have a defs list, or we should have no defs")((void)0);
2025 assert((!DL || DL->size() == ActualDefs.size()) &&((void)0)
2026 "We don't have the same number of defs in the block as on the "((void)0)
2027 "def list")((void)0);
2028 auto ALI = AL->begin();
2029 auto AAI = ActualAccesses.begin();
2030 while (ALI != AL->end() && AAI != ActualAccesses.end()) {
2031 assert(&*ALI == *AAI && "Not the same accesses in the same order")((void)0);
2032 ++ALI;
2033 ++AAI;
2034 }
2035 ActualAccesses.clear();
2036 if (DL) {
2037 auto DLI = DL->begin();
2038 auto ADI = ActualDefs.begin();
2039 while (DLI != DL->end() && ADI != ActualDefs.end()) {
2040 assert(&*DLI == *ADI && "Not the same defs in the same order")((void)0);
2041 ++DLI;
2042 ++ADI;
2043 }
2044 }
2045 ActualDefs.clear();
2046 }
2047#endif
2048}
2049
2050/// Verify the def-use lists in MemorySSA, by verifying that \p Use
2051/// appears in the use list of \p Def.
2052void MemorySSA::verifyUseInDefs(MemoryAccess *Def, MemoryAccess *Use) const {
2053#ifndef NDEBUG1
2054 // The live on entry use may cause us to get a NULL def here
2055 if (!Def)
2056 assert(isLiveOnEntryDef(Use) &&((void)0)
2057 "Null def but use not point to live on entry def")((void)0);
2058 else
2059 assert(is_contained(Def->users(), Use) &&((void)0)
2060 "Did not find use in def's use list")((void)0);
2061#endif
2062}
2063
2064/// Perform a local numbering on blocks so that instruction ordering can be
2065/// determined in constant time.
2066/// TODO: We currently just number in order. If we numbered by N, we could
2067/// allow at least N-1 sequences of insertBefore or insertAfter (and at least
2068/// log2(N) sequences of mixed before and after) without needing to invalidate
2069/// the numbering.
2070void MemorySSA::renumberBlock(const BasicBlock *B) const {
2071 // The pre-increment ensures the numbers really start at 1.
2072 unsigned long CurrentNumber = 0;
2073 const AccessList *AL = getBlockAccesses(B);
2074 assert(AL != nullptr && "Asking to renumber an empty block")((void)0);
2075 for (const auto &I : *AL)
2076 BlockNumbering[&I] = ++CurrentNumber;
2077 BlockNumberingValid.insert(B);
2078}
2079
2080/// Determine, for two memory accesses in the same block,
2081/// whether \p Dominator dominates \p Dominatee.
2082/// \returns True if \p Dominator dominates \p Dominatee.
2083bool MemorySSA::locallyDominates(const MemoryAccess *Dominator,
2084 const MemoryAccess *Dominatee) const {
2085 const BasicBlock *DominatorBlock = Dominator->getBlock();
2086
2087 assert((DominatorBlock == Dominatee->getBlock()) &&((void)0)
2088 "Asking for local domination when accesses are in different blocks!")((void)0);
2089 // A node dominates itself.
2090 if (Dominatee == Dominator)
2091 return true;
2092
2093 // When Dominatee is defined on function entry, it is not dominated by another
2094 // memory access.
2095 if (isLiveOnEntryDef(Dominatee))
2096 return false;
2097
2098 // When Dominator is defined on function entry, it dominates the other memory
2099 // access.
2100 if (isLiveOnEntryDef(Dominator))
2101 return true;
2102
2103 if (!BlockNumberingValid.count(DominatorBlock))
2104 renumberBlock(DominatorBlock);
2105
2106 unsigned long DominatorNum = BlockNumbering.lookup(Dominator);
2107 // All numbers start with 1
2108 assert(DominatorNum != 0 && "Block was not numbered properly")((void)0);
2109 unsigned long DominateeNum = BlockNumbering.lookup(Dominatee);
2110 assert(DominateeNum != 0 && "Block was not numbered properly")((void)0);
2111 return DominatorNum < DominateeNum;
2112}
2113
2114bool MemorySSA::dominates(const MemoryAccess *Dominator,
2115 const MemoryAccess *Dominatee) const {
2116 if (Dominator == Dominatee)
2117 return true;
2118
2119 if (isLiveOnEntryDef(Dominatee))
2120 return false;
2121
2122 if (Dominator->getBlock() != Dominatee->getBlock())
2123 return DT->dominates(Dominator->getBlock(), Dominatee->getBlock());
2124 return locallyDominates(Dominator, Dominatee);
2125}
2126
2127bool MemorySSA::dominates(const MemoryAccess *Dominator,
2128 const Use &Dominatee) const {
2129 if (MemoryPhi *MP = dyn_cast<MemoryPhi>(Dominatee.getUser())) {
2130 BasicBlock *UseBB = MP->getIncomingBlock(Dominatee);
2131 // The def must dominate the incoming block of the phi.
2132 if (UseBB != Dominator->getBlock())
2133 return DT->dominates(Dominator->getBlock(), UseBB);
2134 // If the UseBB and the DefBB are the same, compare locally.
2135 return locallyDominates(Dominator, cast<MemoryAccess>(Dominatee));
2136 }
2137 // If it's not a PHI node use, the normal dominates can already handle it.
2138 return dominates(Dominator, cast<MemoryAccess>(Dominatee.getUser()));
2139}
2140
2141const static char LiveOnEntryStr[] = "liveOnEntry";
2142
2143void MemoryAccess::print(raw_ostream &OS) const {
2144 switch (getValueID()) {
2145 case MemoryPhiVal: return static_cast<const MemoryPhi *>(this)->print(OS);
2146 case MemoryDefVal: return static_cast<const MemoryDef *>(this)->print(OS);
2147 case MemoryUseVal: return static_cast<const MemoryUse *>(this)->print(OS);
2148 }
2149 llvm_unreachable("invalid value id")__builtin_unreachable();
2150}
2151
2152void MemoryDef::print(raw_ostream &OS) const {
2153 MemoryAccess *UO = getDefiningAccess();
2154
2155 auto printID = [&OS](MemoryAccess *A) {
2156 if (A && A->getID())
2157 OS << A->getID();
2158 else
2159 OS << LiveOnEntryStr;
2160 };
2161
2162 OS << getID() << " = MemoryDef(";
2163 printID(UO);
2164 OS << ")";
2165
2166 if (isOptimized()) {
2167 OS << "->";
2168 printID(getOptimized());
2169
2170 if (Optional<AliasResult> AR = getOptimizedAccessType())
2171 OS << " " << *AR;
2172 }
2173}
2174
2175void MemoryPhi::print(raw_ostream &OS) const {
2176 ListSeparator LS(",");
2177 OS << getID() << " = MemoryPhi(";
2178 for (const auto &Op : operands()) {
2179 BasicBlock *BB = getIncomingBlock(Op);
2180 MemoryAccess *MA = cast<MemoryAccess>(Op);
2181
2182 OS << LS << '{';
2183 if (BB->hasName())
2184 OS << BB->getName();
2185 else
2186 BB->printAsOperand(OS, false);
2187 OS << ',';
2188 if (unsigned ID = MA->getID())
2189 OS << ID;
2190 else
2191 OS << LiveOnEntryStr;
2192 OS << '}';
2193 }
2194 OS << ')';
2195}
2196
2197void MemoryUse::print(raw_ostream &OS) const {
2198 MemoryAccess *UO = getDefiningAccess();
2199 OS << "MemoryUse(";
2200 if (UO && UO->getID())
2201 OS << UO->getID();
2202 else
2203 OS << LiveOnEntryStr;
2204 OS << ')';
2205
2206 if (Optional<AliasResult> AR = getOptimizedAccessType())
2207 OS << " " << *AR;
2208}
2209
2210void MemoryAccess::dump() const {
2211// Cannot completely remove virtual function even in release mode.
2212#if !defined(NDEBUG1) || defined(LLVM_ENABLE_DUMP)
2213 print(dbgs());
2214 dbgs() << "\n";
2215#endif
2216}
2217
2218char MemorySSAPrinterLegacyPass::ID = 0;
2219
2220MemorySSAPrinterLegacyPass::MemorySSAPrinterLegacyPass() : FunctionPass(ID) {
2221 initializeMemorySSAPrinterLegacyPassPass(*PassRegistry::getPassRegistry());
2222}
2223
2224void MemorySSAPrinterLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
2225 AU.setPreservesAll();
2226 AU.addRequired<MemorySSAWrapperPass>();
2227}
2228
2229class DOTFuncMSSAInfo {
2230private:
2231 const Function &F;
2232 MemorySSAAnnotatedWriter MSSAWriter;
2233
2234public:
2235 DOTFuncMSSAInfo(const Function &F, MemorySSA &MSSA)
2236 : F(F), MSSAWriter(&MSSA) {}
2237
2238 const Function *getFunction() { return &F; }
2239 MemorySSAAnnotatedWriter &getWriter() { return MSSAWriter; }
2240};
2241
2242namespace llvm {
2243
2244template <>
2245struct GraphTraits<DOTFuncMSSAInfo *> : public GraphTraits<const BasicBlock *> {
2246 static NodeRef getEntryNode(DOTFuncMSSAInfo *CFGInfo) {
2247 return &(CFGInfo->getFunction()->getEntryBlock());
2248 }
2249
2250 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
2251 using nodes_iterator = pointer_iterator<Function::const_iterator>;
2252
2253 static nodes_iterator nodes_begin(DOTFuncMSSAInfo *CFGInfo) {
2254 return nodes_iterator(CFGInfo->getFunction()->begin());
2255 }
2256
2257 static nodes_iterator nodes_end(DOTFuncMSSAInfo *CFGInfo) {
2258 return nodes_iterator(CFGInfo->getFunction()->end());
2259 }
2260
2261 static size_t size(DOTFuncMSSAInfo *CFGInfo) {
2262 return CFGInfo->getFunction()->size();
2263 }
2264};
2265
2266template <>
2267struct DOTGraphTraits<DOTFuncMSSAInfo *> : public DefaultDOTGraphTraits {
2268
2269 DOTGraphTraits(bool IsSimple = false) : DefaultDOTGraphTraits(IsSimple) {}
2270
2271 static std::string getGraphName(DOTFuncMSSAInfo *CFGInfo) {
2272 return "MSSA CFG for '" + CFGInfo->getFunction()->getName().str() +
2273 "' function";
2274 }
2275
2276 std::string getNodeLabel(const BasicBlock *Node, DOTFuncMSSAInfo *CFGInfo) {
2277 return DOTGraphTraits<DOTFuncInfo *>::getCompleteNodeLabel(
2278 Node, nullptr,
2279 [CFGInfo](raw_string_ostream &OS, const BasicBlock &BB) -> void {
2280 BB.print(OS, &CFGInfo->getWriter(), true, true);
2281 },
2282 [](std::string &S, unsigned &I, unsigned Idx) -> void {
2283 std::string Str = S.substr(I, Idx - I);
2284 StringRef SR = Str;
2285 if (SR.count(" = MemoryDef(") || SR.count(" = MemoryPhi(") ||
2286 SR.count("MemoryUse("))
2287 return;
2288 DOTGraphTraits<DOTFuncInfo *>::eraseComment(S, I, Idx);
2289 });
2290 }
2291
2292 static std::string getEdgeSourceLabel(const BasicBlock *Node,
2293 const_succ_iterator I) {
2294 return DOTGraphTraits<DOTFuncInfo *>::getEdgeSourceLabel(Node, I);
2295 }
2296
2297 /// Display the raw branch weights from PGO.
2298 std::string getEdgeAttributes(const BasicBlock *Node, const_succ_iterator I,
2299 DOTFuncMSSAInfo *CFGInfo) {
2300 return "";
2301 }
2302
2303 std::string getNodeAttributes(const BasicBlock *Node,
2304 DOTFuncMSSAInfo *CFGInfo) {
2305 return getNodeLabel(Node, CFGInfo).find(';') != std::string::npos
2306 ? "style=filled, fillcolor=lightpink"
2307 : "";
2308 }
2309};
2310
2311} // namespace llvm
2312
2313bool MemorySSAPrinterLegacyPass::runOnFunction(Function &F) {
2314 auto &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA();
2315 if (DotCFGMSSA != "") {
2316 DOTFuncMSSAInfo CFGInfo(F, MSSA);
2317 WriteGraph(&CFGInfo, "", false, "MSSA", DotCFGMSSA);
2318 } else
2319 MSSA.print(dbgs());
2320
2321 if (VerifyMemorySSA)
2322 MSSA.verifyMemorySSA();
2323 return false;
2324}
2325
2326AnalysisKey MemorySSAAnalysis::Key;
2327
2328MemorySSAAnalysis::Result MemorySSAAnalysis::run(Function &F,
2329 FunctionAnalysisManager &AM) {
2330 auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
2331 auto &AA = AM.getResult<AAManager>(F);
2332 return MemorySSAAnalysis::Result(std::make_unique<MemorySSA>(F, &AA, &DT));
2333}
2334
2335bool MemorySSAAnalysis::Result::invalidate(
2336 Function &F, const PreservedAnalyses &PA,
2337 FunctionAnalysisManager::Invalidator &Inv) {
2338 auto PAC = PA.getChecker<MemorySSAAnalysis>();
2339 return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
2340 Inv.invalidate<AAManager>(F, PA) ||
2341 Inv.invalidate<DominatorTreeAnalysis>(F, PA);
2342}
2343
2344PreservedAnalyses MemorySSAPrinterPass::run(Function &F,
2345 FunctionAnalysisManager &AM) {
2346 auto &MSSA = AM.getResult<MemorySSAAnalysis>(F).getMSSA();
2347 if (DotCFGMSSA != "") {
2348 DOTFuncMSSAInfo CFGInfo(F, MSSA);
2349 WriteGraph(&CFGInfo, "", false, "MSSA", DotCFGMSSA);
2350 } else {
2351 OS << "MemorySSA for function: " << F.getName() << "\n";
2352 MSSA.print(OS);
2353 }
2354
2355 return PreservedAnalyses::all();
2356}
2357
2358PreservedAnalyses MemorySSAVerifierPass::run(Function &F,
2359 FunctionAnalysisManager &AM) {
2360 AM.getResult<MemorySSAAnalysis>(F).getMSSA().verifyMemorySSA();
2361
2362 return PreservedAnalyses::all();
2363}
2364
2365char MemorySSAWrapperPass::ID = 0;
2366
2367MemorySSAWrapperPass::MemorySSAWrapperPass() : FunctionPass(ID) {
2368 initializeMemorySSAWrapperPassPass(*PassRegistry::getPassRegistry());
2369}
2370
2371void MemorySSAWrapperPass::releaseMemory() { MSSA.reset(); }
2372
2373void MemorySSAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
2374 AU.setPreservesAll();
2375 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
2376 AU.addRequiredTransitive<AAResultsWrapperPass>();
2377}
2378
2379bool MemorySSAWrapperPass::runOnFunction(Function &F) {
2380 auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2381 auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
2382 MSSA.reset(new MemorySSA(F, &AA, &DT));
2383 return false;
2384}
2385
2386void MemorySSAWrapperPass::verifyAnalysis() const {
2387 if (VerifyMemorySSA)
2388 MSSA->verifyMemorySSA();
2389}
2390
2391void MemorySSAWrapperPass::print(raw_ostream &OS, const Module *M) const {
2392 MSSA->print(OS);
2393}
2394
2395MemorySSAWalker::MemorySSAWalker(MemorySSA *M) : MSSA(M) {}
2396
2397/// Walk the use-def chains starting at \p StartingAccess and find
2398/// the MemoryAccess that actually clobbers Loc.
2399///
2400/// \returns our clobbering memory access
2401template <typename AliasAnalysisType>
2402MemoryAccess *
2403MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
2404 MemoryAccess *StartingAccess, const MemoryLocation &Loc,
2405 unsigned &UpwardWalkLimit) {
2406 assert(!isa<MemoryUse>(StartingAccess) && "Use cannot be defining access")((void)0);
2407
2408 Instruction *I = nullptr;
2409 if (auto *StartingUseOrDef
3.1
'StartingUseOrDef' is null
3.1
'StartingUseOrDef' is null
3.1
'StartingUseOrDef' is null
= dyn_cast<MemoryUseOrDef>(StartingAccess)) {
3
Assuming 'StartingAccess' is not a 'MemoryUseOrDef'
4
Taking false branch
2410 if (MSSA->isLiveOnEntryDef(StartingUseOrDef))
2411 return StartingUseOrDef;
2412
2413 I = StartingUseOrDef->getMemoryInst();
2414
2415 // Conservatively, fences are always clobbers, so don't perform the walk if
2416 // we hit a fence.
2417 if (!isa<CallBase>(I) && I->isFenceLike())
2418 return StartingUseOrDef;
2419 }
2420
2421 UpwardsMemoryQuery Q;
2422 Q.OriginalAccess = StartingAccess;
2423 Q.StartingLoc = Loc;
2424 Q.Inst = nullptr;
2425 Q.IsCall = false;
2426
2427 // Unlike the other function, do not walk to the def of a def, because we are
2428 // handed something we already believe is the clobbering access.
2429 // We never set SkipSelf to true in Q in this method.
2430 MemoryAccess *Clobber =
2431 Walker.findClobber(StartingAccess, Q, UpwardWalkLimit);
5
Calling 'ClobberWalker::findClobber'
2432 LLVM_DEBUG({do { } while (false)
2433 dbgs() << "Clobber starting at access " << *StartingAccess << "\n";do { } while (false)
2434 if (I)do { } while (false)
2435 dbgs() << " for instruction " << *I << "\n";do { } while (false)
2436 dbgs() << " is " << *Clobber << "\n";do { } while (false)
2437 })do { } while (false);
2438 return Clobber;
2439}
2440
2441template <typename AliasAnalysisType>
2442MemoryAccess *
2443MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
2444 MemoryAccess *MA, unsigned &UpwardWalkLimit, bool SkipSelf) {
2445 auto *StartingAccess = dyn_cast<MemoryUseOrDef>(MA);
2446 // If this is a MemoryPhi, we can't do anything.
2447 if (!StartingAccess)
2448 return MA;
2449
2450 bool IsOptimized = false;
2451
2452 // If this is an already optimized use or def, return the optimized result.
2453 // Note: Currently, we store the optimized def result in a separate field,
2454 // since we can't use the defining access.
2455 if (StartingAccess->isOptimized()) {
2456 if (!SkipSelf || !isa<MemoryDef>(StartingAccess))
2457 return StartingAccess->getOptimized();
2458 IsOptimized = true;
2459 }
2460
2461 const Instruction *I = StartingAccess->getMemoryInst();
2462 // We can't sanely do anything with a fence, since they conservatively clobber
2463 // all memory, and have no locations to get pointers from to try to
2464 // disambiguate.
2465 if (!isa<CallBase>(I) && I->isFenceLike())
2466 return StartingAccess;
2467
2468 UpwardsMemoryQuery Q(I, StartingAccess);
2469
2470 if (isUseTriviallyOptimizableToLiveOnEntry(*Walker.getAA(), I)) {
2471 MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
2472 StartingAccess->setOptimized(LiveOnEntry);
2473 StartingAccess->setOptimizedAccessType(None);
2474 return LiveOnEntry;
2475 }
2476
2477 MemoryAccess *OptimizedAccess;
2478 if (!IsOptimized) {
2479 // Start with the thing we already think clobbers this location
2480 MemoryAccess *DefiningAccess = StartingAccess->getDefiningAccess();
2481
2482 // At this point, DefiningAccess may be the live on entry def.
2483 // If it is, we will not get a better result.
2484 if (MSSA->isLiveOnEntryDef(DefiningAccess)) {
2485 StartingAccess->setOptimized(DefiningAccess);
2486 StartingAccess->setOptimizedAccessType(None);
2487 return DefiningAccess;
2488 }
2489
2490 OptimizedAccess = Walker.findClobber(DefiningAccess, Q, UpwardWalkLimit);
2491 StartingAccess->setOptimized(OptimizedAccess);
2492 if (MSSA->isLiveOnEntryDef(OptimizedAccess))
2493 StartingAccess->setOptimizedAccessType(None);
2494 else if (Q.AR && *Q.AR == AliasResult::MustAlias)
2495 StartingAccess->setOptimizedAccessType(
2496 AliasResult(AliasResult::MustAlias));
2497 } else
2498 OptimizedAccess = StartingAccess->getOptimized();
2499
2500 LLVM_DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ")do { } while (false);
2501 LLVM_DEBUG(dbgs() << *StartingAccess << "\n")do { } while (false);
2502 LLVM_DEBUG(dbgs() << "Optimized Memory SSA clobber for " << *I << " is ")do { } while (false);
2503 LLVM_DEBUG(dbgs() << *OptimizedAccess << "\n")do { } while (false);
2504
2505 MemoryAccess *Result;
2506 if (SkipSelf && isa<MemoryPhi>(OptimizedAccess) &&
2507 isa<MemoryDef>(StartingAccess) && UpwardWalkLimit) {
2508 assert(isa<MemoryDef>(Q.OriginalAccess))((void)0);
2509 Q.SkipSelfAccess = true;
2510 Result = Walker.findClobber(OptimizedAccess, Q, UpwardWalkLimit);
2511 } else
2512 Result = OptimizedAccess;
2513
2514 LLVM_DEBUG(dbgs() << "Result Memory SSA clobber [SkipSelf = " << SkipSelf)do { } while (false);
2515 LLVM_DEBUG(dbgs() << "] for " << *I << " is " << *Result << "\n")do { } while (false);
2516
2517 return Result;
2518}
2519
2520MemoryAccess *
2521DoNothingMemorySSAWalker::getClobberingMemoryAccess(MemoryAccess *MA) {
2522 if (auto *Use = dyn_cast<MemoryUseOrDef>(MA))
2523 return Use->getDefiningAccess();
2524 return MA;
2525}
2526
2527MemoryAccess *DoNothingMemorySSAWalker::getClobberingMemoryAccess(
2528 MemoryAccess *StartingAccess, const MemoryLocation &) {
2529 if (auto *Use = dyn_cast<MemoryUseOrDef>(StartingAccess))
2530 return Use->getDefiningAccess();
2531 return StartingAccess;
2532}
2533
2534void MemoryPhi::deleteMe(DerivedUser *Self) {
2535 delete static_cast<MemoryPhi *>(Self);
2536}
2537
2538void MemoryDef::deleteMe(DerivedUser *Self) {
2539 delete static_cast<MemoryDef *>(Self);
2540}
2541
2542void MemoryUse::deleteMe(DerivedUser *Self) {
2543 delete static_cast<MemoryUse *>(Self);
2544}
2545
2546bool upward_defs_iterator::IsGuaranteedLoopInvariant(Value *Ptr) const {
2547 auto IsGuaranteedLoopInvariantBase = [](Value *Ptr) {
2548 Ptr = Ptr->stripPointerCasts();
2549 if (!isa<Instruction>(Ptr))
2550 return true;
2551 return isa<AllocaInst>(Ptr);
2552 };
2553
2554 Ptr = Ptr->stripPointerCasts();
2555 if (auto *I = dyn_cast<Instruction>(Ptr)) {
2556 if (I->getParent()->isEntryBlock())
2557 return true;
2558 }
2559 if (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
2560 return IsGuaranteedLoopInvariantBase(GEP->getPointerOperand()) &&
2561 GEP->hasAllConstantIndices();
2562 }
2563 return IsGuaranteedLoopInvariantBase(Ptr);
2564}

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

1//===- Optional.h - Simple variant for passing optional values --*- 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 provides Optional, a template class modeled in the spirit of
10// OCaml's 'opt' variant. The idea is to strongly type whether or not
11// a value can be optional.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_ADT_OPTIONAL_H
16#define LLVM_ADT_OPTIONAL_H
17
18#include "llvm/ADT/Hashing.h"
19#include "llvm/ADT/None.h"
20#include "llvm/ADT/STLForwardCompat.h"
21#include "llvm/Support/Compiler.h"
22#include "llvm/Support/type_traits.h"
23#include <cassert>
24#include <memory>
25#include <new>
26#include <utility>
27
28namespace llvm {
29
30class raw_ostream;
31
32namespace optional_detail {
33
34/// Storage for any type.
35//
36// The specialization condition intentionally uses
37// llvm::is_trivially_copy_constructible instead of
38// std::is_trivially_copy_constructible. GCC versions prior to 7.4 may
39// instantiate the copy constructor of `T` when
40// std::is_trivially_copy_constructible is instantiated. This causes
41// compilation to fail if we query the trivially copy constructible property of
42// a class which is not copy constructible.
43//
44// The current implementation of OptionalStorage insists that in order to use
45// the trivial specialization, the value_type must be trivially copy
46// constructible and trivially copy assignable due to =default implementations
47// of the copy/move constructor/assignment. It does not follow that this is
48// necessarily the case std::is_trivially_copyable is true (hence the expanded
49// specialization condition).
50//
51// The move constructible / assignable conditions emulate the remaining behavior
52// of std::is_trivially_copyable.
53template <typename T, bool = (llvm::is_trivially_copy_constructible<T>::value &&
54 std::is_trivially_copy_assignable<T>::value &&
55 (std::is_trivially_move_constructible<T>::value ||
56 !std::is_move_constructible<T>::value) &&
57 (std::is_trivially_move_assignable<T>::value ||
58 !std::is_move_assignable<T>::value))>
59class OptionalStorage {
60 union {
61 char empty;
62 T value;
63 };
64 bool hasVal;
65
66public:
67 ~OptionalStorage() { reset(); }
68
69 constexpr OptionalStorage() noexcept : empty(), hasVal(false) {}
70
71 constexpr OptionalStorage(OptionalStorage const &other) : OptionalStorage() {
72 if (other.hasValue()) {
73 emplace(other.value);
74 }
75 }
76 constexpr OptionalStorage(OptionalStorage &&other) : OptionalStorage() {
77 if (other.hasValue()) {
78 emplace(std::move(other.value));
79 }
80 }
81
82 template <class... Args>
83 constexpr explicit OptionalStorage(in_place_t, Args &&... args)
84 : value(std::forward<Args>(args)...), hasVal(true) {}
85
86 void reset() noexcept {
87 if (hasVal) {
88 value.~T();
89 hasVal = false;
90 }
91 }
92
93 constexpr bool hasValue() const noexcept { return hasVal; }
94
95 T &getValue() LLVM_LVALUE_FUNCTION& noexcept {
96 assert(hasVal)((void)0);
97 return value;
98 }
99 constexpr T const &getValue() const LLVM_LVALUE_FUNCTION& noexcept {
100 assert(hasVal)((void)0);
101 return value;
102 }
103#if LLVM_HAS_RVALUE_REFERENCE_THIS1
104 T &&getValue() && noexcept {
105 assert(hasVal)((void)0);
106 return std::move(value);
107 }
108#endif
109
110 template <class... Args> void emplace(Args &&... args) {
111 reset();
112 ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...);
113 hasVal = true;
114 }
115
116 OptionalStorage &operator=(T const &y) {
117 if (hasValue()) {
118 value = y;
119 } else {
120 ::new ((void *)std::addressof(value)) T(y);
121 hasVal = true;
122 }
123 return *this;
124 }
125 OptionalStorage &operator=(T &&y) {
126 if (hasValue()) {
127 value = std::move(y);
128 } else {
129 ::new ((void *)std::addressof(value)) T(std::move(y));
130 hasVal = true;
131 }
132 return *this;
133 }
134
135 OptionalStorage &operator=(OptionalStorage const &other) {
136 if (other.hasValue()) {
137 if (hasValue()) {
138 value = other.value;
139 } else {
140 ::new ((void *)std::addressof(value)) T(other.value);
141 hasVal = true;
142 }
143 } else {
144 reset();
145 }
146 return *this;
147 }
148
149 OptionalStorage &operator=(OptionalStorage &&other) {
150 if (other.hasValue()) {
151 if (hasValue()) {
152 value = std::move(other.value);
153 } else {
154 ::new ((void *)std::addressof(value)) T(std::move(other.value));
155 hasVal = true;
156 }
157 } else {
158 reset();
159 }
160 return *this;
161 }
162};
163
164template <typename T> class OptionalStorage<T, true> {
165 union {
166 char empty;
167 T value;
168 };
169 bool hasVal = false;
170
171public:
172 ~OptionalStorage() = default;
173
174 constexpr OptionalStorage() noexcept : empty{} {}
175
176 constexpr OptionalStorage(OptionalStorage const &other) = default;
177 constexpr OptionalStorage(OptionalStorage &&other) = default;
178
179 OptionalStorage &operator=(OptionalStorage const &other) = default;
180 OptionalStorage &operator=(OptionalStorage &&other) = default;
181
182 template <class... Args>
183 constexpr explicit OptionalStorage(in_place_t, Args &&... args)
184 : value(std::forward<Args>(args)...), hasVal(true) {}
185
186 void reset() noexcept {
187 if (hasVal) {
188 value.~T();
189 hasVal = false;
190 }
191 }
192
193 constexpr bool hasValue() const noexcept { return hasVal; }
22
Returning zero, which participates in a condition later
194
195 T &getValue() LLVM_LVALUE_FUNCTION& noexcept {
196 assert(hasVal)((void)0);
197 return value;
198 }
199 constexpr T const &getValue() const LLVM_LVALUE_FUNCTION& noexcept {
200 assert(hasVal)((void)0);
201 return value;
202 }
203#if LLVM_HAS_RVALUE_REFERENCE_THIS1
204 T &&getValue() && noexcept {
205 assert(hasVal)((void)0);
206 return std::move(value);
207 }
208#endif
209
210 template <class... Args> void emplace(Args &&... args) {
211 reset();
212 ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...);
213 hasVal = true;
214 }
215
216 OptionalStorage &operator=(T const &y) {
217 if (hasValue()) {
218 value = y;
219 } else {
220 ::new ((void *)std::addressof(value)) T(y);
221 hasVal = true;
222 }
223 return *this;
224 }
225 OptionalStorage &operator=(T &&y) {
226 if (hasValue()) {
227 value = std::move(y);
228 } else {
229 ::new ((void *)std::addressof(value)) T(std::move(y));
230 hasVal = true;
231 }
232 return *this;
233 }
234};
235
236} // namespace optional_detail
237
238template <typename T> class Optional {
239 optional_detail::OptionalStorage<T> Storage;
240
241public:
242 using value_type = T;
243
244 constexpr Optional() {}
245 constexpr Optional(NoneType) {}
246
247 constexpr Optional(const T &y) : Storage(in_place, y) {}
248 constexpr Optional(const Optional &O) = default;
249
250 constexpr Optional(T &&y) : Storage(in_place, std::move(y)) {}
251 constexpr Optional(Optional &&O) = default;
252
253 template <typename... ArgTypes>
254 constexpr Optional(in_place_t, ArgTypes &&...Args)
255 : Storage(in_place, std::forward<ArgTypes>(Args)...) {}
256
257 Optional &operator=(T &&y) {
258 Storage = std::move(y);
259 return *this;
260 }
261 Optional &operator=(Optional &&O) = default;
262
263 /// Create a new object by constructing it in place with the given arguments.
264 template <typename... ArgTypes> void emplace(ArgTypes &&... Args) {
265 Storage.emplace(std::forward<ArgTypes>(Args)...);
266 }
267
268 static constexpr Optional create(const T *y) {
269 return y ? Optional(*y) : Optional();
270 }
271
272 Optional &operator=(const T &y) {
273 Storage = y;
274 return *this;
275 }
276 Optional &operator=(const Optional &O) = default;
277
278 void reset() { Storage.reset(); }
279
280 constexpr const T *getPointer() const { return &Storage.getValue(); }
281 T *getPointer() { return &Storage.getValue(); }
282 constexpr const T &getValue() const LLVM_LVALUE_FUNCTION& {
283 return Storage.getValue();
284 }
285 T &getValue() LLVM_LVALUE_FUNCTION& { return Storage.getValue(); }
286
287 constexpr explicit operator bool() const { return hasValue(); }
20
Calling 'Optional::hasValue'
25
Returning from 'Optional::hasValue'
26
Returning zero, which participates in a condition later
288 constexpr bool hasValue() const { return Storage.hasValue(); }
21
Calling 'OptionalStorage::hasValue'
23
Returning from 'OptionalStorage::hasValue'
24
Returning zero, which participates in a condition later
289 constexpr const T *operator->() const { return getPointer(); }
290 T *operator->() { return getPointer(); }
291 constexpr const T &operator*() const LLVM_LVALUE_FUNCTION& {
292 return getValue();
293 }
294 T &operator*() LLVM_LVALUE_FUNCTION& { return getValue(); }
295
296 template <typename U>
297 constexpr T getValueOr(U &&value) const LLVM_LVALUE_FUNCTION& {
298 return hasValue() ? getValue() : std::forward<U>(value);
299 }
300
301 /// Apply a function to the value if present; otherwise return None.
302 template <class Function>
303 auto map(const Function &F) const LLVM_LVALUE_FUNCTION&
304 -> Optional<decltype(F(getValue()))> {
305 if (*this) return F(getValue());
306 return None;
307 }
308
309#if LLVM_HAS_RVALUE_REFERENCE_THIS1
310 T &&getValue() && { return std::move(Storage.getValue()); }
311 T &&operator*() && { return std::move(Storage.getValue()); }
312
313 template <typename U>
314 T getValueOr(U &&value) && {
315 return hasValue() ? std::move(getValue()) : std::forward<U>(value);
316 }
317
318 /// Apply a function to the value if present; otherwise return None.
319 template <class Function>
320 auto map(const Function &F) &&
321 -> Optional<decltype(F(std::move(*this).getValue()))> {
322 if (*this) return F(std::move(*this).getValue());
323 return None;
324 }
325#endif
326};
327
328template <class T> llvm::hash_code hash_value(const Optional<T> &O) {
329 return O ? hash_combine(true, *O) : hash_value(false);
330}
331
332template <typename T, typename U>
333constexpr bool operator==(const Optional<T> &X, const Optional<U> &Y) {
334 if (X && Y)
335 return *X == *Y;
336 return X.hasValue() == Y.hasValue();
337}
338
339template <typename T, typename U>
340constexpr bool operator!=(const Optional<T> &X, const Optional<U> &Y) {
341 return !(X == Y);
342}
343
344template <typename T, typename U>
345constexpr bool operator<(const Optional<T> &X, const Optional<U> &Y) {
346 if (X && Y)
347 return *X < *Y;
348 return X.hasValue() < Y.hasValue();
349}
350
351template <typename T, typename U>
352constexpr bool operator<=(const Optional<T> &X, const Optional<U> &Y) {
353 return !(Y < X);
354}
355
356template <typename T, typename U>
357constexpr bool operator>(const Optional<T> &X, const Optional<U> &Y) {
358 return Y < X;
359}
360
361template <typename T, typename U>
362constexpr bool operator>=(const Optional<T> &X, const Optional<U> &Y) {
363 return !(X < Y);
364}
365
366template <typename T>
367constexpr bool operator==(const Optional<T> &X, NoneType) {
368 return !X;
369}
370
371template <typename T>
372constexpr bool operator==(NoneType, const Optional<T> &X) {
373 return X == None;
374}
375
376template <typename T>
377constexpr bool operator!=(const Optional<T> &X, NoneType) {
378 return !(X == None);
379}
380
381template <typename T>
382constexpr bool operator!=(NoneType, const Optional<T> &X) {
383 return X != None;
384}
385
386template <typename T> constexpr bool operator<(const Optional<T> &, NoneType) {
387 return false;
388}
389
390template <typename T> constexpr bool operator<(NoneType, const Optional<T> &X) {
391 return X.hasValue();
392}
393
394template <typename T>
395constexpr bool operator<=(const Optional<T> &X, NoneType) {
396 return !(None < X);
397}
398
399template <typename T>
400constexpr bool operator<=(NoneType, const Optional<T> &X) {
401 return !(X < None);
402}
403
404template <typename T> constexpr bool operator>(const Optional<T> &X, NoneType) {
405 return None < X;
406}
407
408template <typename T> constexpr bool operator>(NoneType, const Optional<T> &X) {
409 return X < None;
410}
411
412template <typename T>
413constexpr bool operator>=(const Optional<T> &X, NoneType) {
414 return None <= X;
415}
416
417template <typename T>
418constexpr bool operator>=(NoneType, const Optional<T> &X) {
419 return X <= None;
420}
421
422template <typename T>
423constexpr bool operator==(const Optional<T> &X, const T &Y) {
424 return X && *X == Y;
425}
426
427template <typename T>
428constexpr bool operator==(const T &X, const Optional<T> &Y) {
429 return Y && X == *Y;
430}
431
432template <typename T>
433constexpr bool operator!=(const Optional<T> &X, const T &Y) {
434 return !(X == Y);
435}
436
437template <typename T>
438constexpr bool operator!=(const T &X, const Optional<T> &Y) {
439 return !(X == Y);
440}
441
442template <typename T>
443constexpr bool operator<(const Optional<T> &X, const T &Y) {
444 return !X || *X < Y;
445}
446
447template <typename T>
448constexpr bool operator<(const T &X, const Optional<T> &Y) {
449 return Y && X < *Y;
450}
451
452template <typename T>
453constexpr bool operator<=(const Optional<T> &X, const T &Y) {
454 return !(Y < X);
455}
456
457template <typename T>
458constexpr bool operator<=(const T &X, const Optional<T> &Y) {
459 return !(Y < X);
460}
461
462template <typename T>
463constexpr bool operator>(const Optional<T> &X, const T &Y) {
464 return Y < X;
465}
466
467template <typename T>
468constexpr bool operator>(const T &X, const Optional<T> &Y) {
469 return Y < X;
470}
471
472template <typename T>
473constexpr bool operator>=(const Optional<T> &X, const T &Y) {
474 return !(X < Y);
475}
476
477template <typename T>
478constexpr bool operator>=(const T &X, const Optional<T> &Y) {
479 return !(X < Y);
480}
481
482raw_ostream &operator<<(raw_ostream &OS, NoneType);
483
484template <typename T, typename = decltype(std::declval<raw_ostream &>()
485 << std::declval<const T &>())>
486raw_ostream &operator<<(raw_ostream &OS, const Optional<T> &O) {
487 if (O)
488 OS << *O;
489 else
490 OS << None;
491 return OS;
492}
493
494} // end namespace llvm
495
496#endif // LLVM_ADT_OPTIONAL_H

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

1//===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- 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 SmallVector class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_ADT_SMALLVECTOR_H
14#define LLVM_ADT_SMALLVECTOR_H
15
16#include "llvm/ADT/iterator_range.h"
17#include "llvm/Support/Compiler.h"
18#include "llvm/Support/ErrorHandling.h"
19#include "llvm/Support/MemAlloc.h"
20#include "llvm/Support/type_traits.h"
21#include <algorithm>
22#include <cassert>
23#include <cstddef>
24#include <cstdlib>
25#include <cstring>
26#include <functional>
27#include <initializer_list>
28#include <iterator>
29#include <limits>
30#include <memory>
31#include <new>
32#include <type_traits>
33#include <utility>
34
35namespace llvm {
36
37/// This is all the stuff common to all SmallVectors.
38///
39/// The template parameter specifies the type which should be used to hold the
40/// Size and Capacity of the SmallVector, so it can be adjusted.
41/// Using 32 bit size is desirable to shrink the size of the SmallVector.
42/// Using 64 bit size is desirable for cases like SmallVector<char>, where a
43/// 32 bit size would limit the vector to ~4GB. SmallVectors are used for
44/// buffering bitcode output - which can exceed 4GB.
45template <class Size_T> class SmallVectorBase {
46protected:
47 void *BeginX;
48 Size_T Size = 0, Capacity;
49
50 /// The maximum value of the Size_T used.
51 static constexpr size_t SizeTypeMax() {
52 return std::numeric_limits<Size_T>::max();
53 }
54
55 SmallVectorBase() = delete;
56 SmallVectorBase(void *FirstEl, size_t TotalCapacity)
57 : BeginX(FirstEl), Capacity(TotalCapacity) {}
58
59 /// This is a helper for \a grow() that's out of line to reduce code
60 /// duplication. This function will report a fatal error if it can't grow at
61 /// least to \p MinSize.
62 void *mallocForGrow(size_t MinSize, size_t TSize, size_t &NewCapacity);
63
64 /// This is an implementation of the grow() method which only works
65 /// on POD-like data types and is out of line to reduce code duplication.
66 /// This function will report a fatal error if it cannot increase capacity.
67 void grow_pod(void *FirstEl, size_t MinSize, size_t TSize);
68
69public:
70 size_t size() const { return Size; }
71 size_t capacity() const { return Capacity; }
72
73 LLVM_NODISCARD[[clang::warn_unused_result]] bool empty() const { return !Size; }
30
Assuming field 'Size' is not equal to 0, which participates in a condition later
31
Returning zero, which participates in a condition later
37
Assuming field 'Size' is not equal to 0, which participates in a condition later
38
Returning zero, which participates in a condition later
74
75 /// Set the array size to \p N, which the current array must have enough
76 /// capacity for.
77 ///
78 /// This does not construct or destroy any elements in the vector.
79 ///
80 /// Clients can use this in conjunction with capacity() to write past the end
81 /// of the buffer when they know that more elements are available, and only
82 /// update the size later. This avoids the cost of value initializing elements
83 /// which will only be overwritten.
84 void set_size(size_t N) {
85 assert(N <= capacity())((void)0);
86 Size = N;
87 }
88};
89
90template <class T>
91using SmallVectorSizeType =
92 typename std::conditional<sizeof(T) < 4 && sizeof(void *) >= 8, uint64_t,
93 uint32_t>::type;
94
95/// Figure out the offset of the first element.
96template <class T, typename = void> struct SmallVectorAlignmentAndSize {
97 alignas(SmallVectorBase<SmallVectorSizeType<T>>) char Base[sizeof(
98 SmallVectorBase<SmallVectorSizeType<T>>)];
99 alignas(T) char FirstEl[sizeof(T)];
100};
101
102/// This is the part of SmallVectorTemplateBase which does not depend on whether
103/// the type T is a POD. The extra dummy template argument is used by ArrayRef
104/// to avoid unnecessarily requiring T to be complete.
105template <typename T, typename = void>
106class SmallVectorTemplateCommon
107 : public SmallVectorBase<SmallVectorSizeType<T>> {
108 using Base = SmallVectorBase<SmallVectorSizeType<T>>;
109
110 /// Find the address of the first element. For this pointer math to be valid
111 /// with small-size of 0 for T with lots of alignment, it's important that
112 /// SmallVectorStorage is properly-aligned even for small-size of 0.
113 void *getFirstEl() const {
114 return const_cast<void *>(reinterpret_cast<const void *>(
115 reinterpret_cast<const char *>(this) +
116 offsetof(SmallVectorAlignmentAndSize<T>, FirstEl)__builtin_offsetof(SmallVectorAlignmentAndSize<T>, FirstEl
)
));
117 }
118 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
119
120protected:
121 SmallVectorTemplateCommon(size_t Size) : Base(getFirstEl(), Size) {}
122
123 void grow_pod(size_t MinSize, size_t TSize) {
124 Base::grow_pod(getFirstEl(), MinSize, TSize);
125 }
126
127 /// Return true if this is a smallvector which has not had dynamic
128 /// memory allocated for it.
129 bool isSmall() const { return this->BeginX == getFirstEl(); }
130
131 /// Put this vector in a state of being small.
132 void resetToSmall() {
133 this->BeginX = getFirstEl();
134 this->Size = this->Capacity = 0; // FIXME: Setting Capacity to 0 is suspect.
135 }
136
137 /// Return true if V is an internal reference to the given range.
138 bool isReferenceToRange(const void *V, const void *First, const void *Last) const {
139 // Use std::less to avoid UB.
140 std::less<> LessThan;
141 return !LessThan(V, First) && LessThan(V, Last);
142 }
143
144 /// Return true if V is an internal reference to this vector.
145 bool isReferenceToStorage(const void *V) const {
146 return isReferenceToRange(V, this->begin(), this->end());
147 }
148
149 /// Return true if First and Last form a valid (possibly empty) range in this
150 /// vector's storage.
151 bool isRangeInStorage(const void *First, const void *Last) const {
152 // Use std::less to avoid UB.
153 std::less<> LessThan;
154 return !LessThan(First, this->begin()) && !LessThan(Last, First) &&
155 !LessThan(this->end(), Last);
156 }
157
158 /// Return true unless Elt will be invalidated by resizing the vector to
159 /// NewSize.
160 bool isSafeToReferenceAfterResize(const void *Elt, size_t NewSize) {
161 // Past the end.
162 if (LLVM_LIKELY(!isReferenceToStorage(Elt))__builtin_expect((bool)(!isReferenceToStorage(Elt)), true))
163 return true;
164
165 // Return false if Elt will be destroyed by shrinking.
166 if (NewSize <= this->size())
167 return Elt < this->begin() + NewSize;
168
169 // Return false if we need to grow.
170 return NewSize <= this->capacity();
171 }
172
173 /// Check whether Elt will be invalidated by resizing the vector to NewSize.
174 void assertSafeToReferenceAfterResize(const void *Elt, size_t NewSize) {
175 assert(isSafeToReferenceAfterResize(Elt, NewSize) &&((void)0)
176 "Attempting to reference an element of the vector in an operation "((void)0)
177 "that invalidates it")((void)0);
178 }
179
180 /// Check whether Elt will be invalidated by increasing the size of the
181 /// vector by N.
182 void assertSafeToAdd(const void *Elt, size_t N = 1) {
183 this->assertSafeToReferenceAfterResize(Elt, this->size() + N);
184 }
185
186 /// Check whether any part of the range will be invalidated by clearing.
187 void assertSafeToReferenceAfterClear(const T *From, const T *To) {
188 if (From == To)
189 return;
190 this->assertSafeToReferenceAfterResize(From, 0);
191 this->assertSafeToReferenceAfterResize(To - 1, 0);
192 }
193 template <
194 class ItTy,
195 std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T *>::value,
196 bool> = false>
197 void assertSafeToReferenceAfterClear(ItTy, ItTy) {}
198
199 /// Check whether any part of the range will be invalidated by growing.
200 void assertSafeToAddRange(const T *From, const T *To) {
201 if (From == To)
202 return;
203 this->assertSafeToAdd(From, To - From);
204 this->assertSafeToAdd(To - 1, To - From);
205 }
206 template <
207 class ItTy,
208 std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T *>::value,
209 bool> = false>
210 void assertSafeToAddRange(ItTy, ItTy) {}
211
212 /// Reserve enough space to add one element, and return the updated element
213 /// pointer in case it was a reference to the storage.
214 template <class U>
215 static const T *reserveForParamAndGetAddressImpl(U *This, const T &Elt,
216 size_t N) {
217 size_t NewSize = This->size() + N;
218 if (LLVM_LIKELY(NewSize <= This->capacity())__builtin_expect((bool)(NewSize <= This->capacity()), true
)
)
219 return &Elt;
220
221 bool ReferencesStorage = false;
222 int64_t Index = -1;
223 if (!U::TakesParamByValue) {
224 if (LLVM_UNLIKELY(This->isReferenceToStorage(&Elt))__builtin_expect((bool)(This->isReferenceToStorage(&Elt
)), false)
) {
225 ReferencesStorage = true;
226 Index = &Elt - This->begin();
227 }
228 }
229 This->grow(NewSize);
230 return ReferencesStorage ? This->begin() + Index : &Elt;
231 }
232
233public:
234 using size_type = size_t;
235 using difference_type = ptrdiff_t;
236 using value_type = T;
237 using iterator = T *;
238 using const_iterator = const T *;
239
240 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
241 using reverse_iterator = std::reverse_iterator<iterator>;
242
243 using reference = T &;
244 using const_reference = const T &;
245 using pointer = T *;
246 using const_pointer = const T *;
247
248 using Base::capacity;
249 using Base::empty;
250 using Base::size;
251
252 // forward iterator creation methods.
253 iterator begin() { return (iterator)this->BeginX; }
254 const_iterator begin() const { return (const_iterator)this->BeginX; }
255 iterator end() { return begin() + size(); }
256 const_iterator end() const { return begin() + size(); }
257
258 // reverse iterator creation methods.
259 reverse_iterator rbegin() { return reverse_iterator(end()); }
260 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
261 reverse_iterator rend() { return reverse_iterator(begin()); }
262 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
263
264 size_type size_in_bytes() const { return size() * sizeof(T); }
265 size_type max_size() const {
266 return std::min(this->SizeTypeMax(), size_type(-1) / sizeof(T));
267 }
268
269 size_t capacity_in_bytes() const { return capacity() * sizeof(T); }
270
271 /// Return a pointer to the vector's buffer, even if empty().
272 pointer data() { return pointer(begin()); }
273 /// Return a pointer to the vector's buffer, even if empty().
274 const_pointer data() const { return const_pointer(begin()); }
275
276 reference operator[](size_type idx) {
277 assert(idx < size())((void)0);
278 return begin()[idx];
279 }
280 const_reference operator[](size_type idx) const {
281 assert(idx < size())((void)0);
282 return begin()[idx];
283 }
284
285 reference front() {
286 assert(!empty())((void)0);
287 return begin()[0];
288 }
289 const_reference front() const {
290 assert(!empty())((void)0);
291 return begin()[0];
292 }
293
294 reference back() {
295 assert(!empty())((void)0);
296 return end()[-1];
297 }
298 const_reference back() const {
299 assert(!empty())((void)0);
300 return end()[-1];
301 }
302};
303
304/// SmallVectorTemplateBase<TriviallyCopyable = false> - This is where we put
305/// method implementations that are designed to work with non-trivial T's.
306///
307/// We approximate is_trivially_copyable with trivial move/copy construction and
308/// trivial destruction. While the standard doesn't specify that you're allowed
309/// copy these types with memcpy, there is no way for the type to observe this.
310/// This catches the important case of std::pair<POD, POD>, which is not
311/// trivially assignable.
312template <typename T, bool = (is_trivially_copy_constructible<T>::value) &&
313 (is_trivially_move_constructible<T>::value) &&
314 std::is_trivially_destructible<T>::value>
315class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
316 friend class SmallVectorTemplateCommon<T>;
317
318protected:
319 static constexpr bool TakesParamByValue = false;
320 using ValueParamT = const T &;
321
322 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
323
324 static void destroy_range(T *S, T *E) {
325 while (S != E) {
326 --E;
327 E->~T();
328 }
329 }
330
331 /// Move the range [I, E) into the uninitialized memory starting with "Dest",
332 /// constructing elements as needed.
333 template<typename It1, typename It2>
334 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
335 std::uninitialized_copy(std::make_move_iterator(I),
336 std::make_move_iterator(E), Dest);
337 }
338
339 /// Copy the range [I, E) onto the uninitialized memory starting with "Dest",
340 /// constructing elements as needed.
341 template<typename It1, typename It2>
342 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
343 std::uninitialized_copy(I, E, Dest);
344 }
345
346 /// Grow the allocated memory (without initializing new elements), doubling
347 /// the size of the allocated memory. Guarantees space for at least one more
348 /// element, or MinSize more elements if specified.
349 void grow(size_t MinSize = 0);
350
351 /// Create a new allocation big enough for \p MinSize and pass back its size
352 /// in \p NewCapacity. This is the first section of \a grow().
353 T *mallocForGrow(size_t MinSize, size_t &NewCapacity) {
354 return static_cast<T *>(
355 SmallVectorBase<SmallVectorSizeType<T>>::mallocForGrow(
356 MinSize, sizeof(T), NewCapacity));
357 }
358
359 /// Move existing elements over to the new allocation \p NewElts, the middle
360 /// section of \a grow().
361 void moveElementsForGrow(T *NewElts);
362
363 /// Transfer ownership of the allocation, finishing up \a grow().
364 void takeAllocationForGrow(T *NewElts, size_t NewCapacity);
365
366 /// Reserve enough space to add one element, and return the updated element
367 /// pointer in case it was a reference to the storage.
368 const T *reserveForParamAndGetAddress(const T &Elt, size_t N = 1) {
369 return this->reserveForParamAndGetAddressImpl(this, Elt, N);
370 }
371
372 /// Reserve enough space to add one element, and return the updated element
373 /// pointer in case it was a reference to the storage.
374 T *reserveForParamAndGetAddress(T &Elt, size_t N = 1) {
375 return const_cast<T *>(
376 this->reserveForParamAndGetAddressImpl(this, Elt, N));
377 }
378
379 static T &&forward_value_param(T &&V) { return std::move(V); }
380 static const T &forward_value_param(const T &V) { return V; }
381
382 void growAndAssign(size_t NumElts, const T &Elt) {
383 // Grow manually in case Elt is an internal reference.
384 size_t NewCapacity;
385 T *NewElts = mallocForGrow(NumElts, NewCapacity);
386 std::uninitialized_fill_n(NewElts, NumElts, Elt);
387 this->destroy_range(this->begin(), this->end());
388 takeAllocationForGrow(NewElts, NewCapacity);
389 this->set_size(NumElts);
390 }
391
392 template <typename... ArgTypes> T &growAndEmplaceBack(ArgTypes &&... Args) {
393 // Grow manually in case one of Args is an internal reference.
394 size_t NewCapacity;
395 T *NewElts = mallocForGrow(0, NewCapacity);
396 ::new ((void *)(NewElts + this->size())) T(std::forward<ArgTypes>(Args)...);
397 moveElementsForGrow(NewElts);
398 takeAllocationForGrow(NewElts, NewCapacity);
399 this->set_size(this->size() + 1);
400 return this->back();
401 }
402
403public:
404 void push_back(const T &Elt) {
405 const T *EltPtr = reserveForParamAndGetAddress(Elt);
406 ::new ((void *)this->end()) T(*EltPtr);
407 this->set_size(this->size() + 1);
408 }
409
410 void push_back(T &&Elt) {
411 T *EltPtr = reserveForParamAndGetAddress(Elt);
412 ::new ((void *)this->end()) T(::std::move(*EltPtr));
413 this->set_size(this->size() + 1);
414 }
415
416 void pop_back() {
417 this->set_size(this->size() - 1);
418 this->end()->~T();
419 }
420};
421
422// Define this out-of-line to dissuade the C++ compiler from inlining it.
423template <typename T, bool TriviallyCopyable>
424void SmallVectorTemplateBase<T, TriviallyCopyable>::grow(size_t MinSize) {
425 size_t NewCapacity;
426 T *NewElts = mallocForGrow(MinSize, NewCapacity);
427 moveElementsForGrow(NewElts);
428 takeAllocationForGrow(NewElts, NewCapacity);
429}
430
431// Define this out-of-line to dissuade the C++ compiler from inlining it.
432template <typename T, bool TriviallyCopyable>
433void SmallVectorTemplateBase<T, TriviallyCopyable>::moveElementsForGrow(
434 T *NewElts) {
435 // Move the elements over.
436 this->uninitialized_move(this->begin(), this->end(), NewElts);
437
438 // Destroy the original elements.
439 destroy_range(this->begin(), this->end());
440}
441
442// Define this out-of-line to dissuade the C++ compiler from inlining it.
443template <typename T, bool TriviallyCopyable>
444void SmallVectorTemplateBase<T, TriviallyCopyable>::takeAllocationForGrow(
445 T *NewElts, size_t NewCapacity) {
446 // If this wasn't grown from the inline copy, deallocate the old space.
447 if (!this->isSmall())
448 free(this->begin());
449
450 this->BeginX = NewElts;
451 this->Capacity = NewCapacity;
452}
453
454/// SmallVectorTemplateBase<TriviallyCopyable = true> - This is where we put
455/// method implementations that are designed to work with trivially copyable
456/// T's. This allows using memcpy in place of copy/move construction and
457/// skipping destruction.
458template <typename T>
459class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
460 friend class SmallVectorTemplateCommon<T>;
461
462protected:
463 /// True if it's cheap enough to take parameters by value. Doing so avoids
464 /// overhead related to mitigations for reference invalidation.
465 static constexpr bool TakesParamByValue = sizeof(T) <= 2 * sizeof(void *);
466
467 /// Either const T& or T, depending on whether it's cheap enough to take
468 /// parameters by value.
469 using ValueParamT =
470 typename std::conditional<TakesParamByValue, T, const T &>::type;
471
472 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
473
474 // No need to do a destroy loop for POD's.
475 static void destroy_range(T *, T *) {}
476
477 /// Move the range [I, E) onto the uninitialized memory
478 /// starting with "Dest", constructing elements into it as needed.
479 template<typename It1, typename It2>
480 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
481 // Just do a copy.
482 uninitialized_copy(I, E, Dest);
483 }
484
485 /// Copy the range [I, E) onto the uninitialized memory
486 /// starting with "Dest", constructing elements into it as needed.
487 template<typename It1, typename It2>
488 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
489 // Arbitrary iterator types; just use the basic implementation.
490 std::uninitialized_copy(I, E, Dest);
491 }
492
493 /// Copy the range [I, E) onto the uninitialized memory
494 /// starting with "Dest", constructing elements into it as needed.
495 template <typename T1, typename T2>
496 static void uninitialized_copy(
497 T1 *I, T1 *E, T2 *Dest,
498 std::enable_if_t<std::is_same<typename std::remove_const<T1>::type,
499 T2>::value> * = nullptr) {
500 // Use memcpy for PODs iterated by pointers (which includes SmallVector
501 // iterators): std::uninitialized_copy optimizes to memmove, but we can
502 // use memcpy here. Note that I and E are iterators and thus might be
503 // invalid for memcpy if they are equal.
504 if (I != E)
505 memcpy(reinterpret_cast<void *>(Dest), I, (E - I) * sizeof(T));
506 }
507
508 /// Double the size of the allocated memory, guaranteeing space for at
509 /// least one more element or MinSize if specified.
510 void grow(size_t MinSize = 0) { this->grow_pod(MinSize, sizeof(T)); }
511
512 /// Reserve enough space to add one element, and return the updated element
513 /// pointer in case it was a reference to the storage.
514 const T *reserveForParamAndGetAddress(const T &Elt, size_t N = 1) {
515 return this->reserveForParamAndGetAddressImpl(this, Elt, N);
516 }
517
518 /// Reserve enough space to add one element, and return the updated element
519 /// pointer in case it was a reference to the storage.
520 T *reserveForParamAndGetAddress(T &Elt, size_t N = 1) {
521 return const_cast<T *>(
522 this->reserveForParamAndGetAddressImpl(this, Elt, N));
523 }
524
525 /// Copy \p V or return a reference, depending on \a ValueParamT.
526 static ValueParamT forward_value_param(ValueParamT V) { return V; }
527
528 void growAndAssign(size_t NumElts, T Elt) {
529 // Elt has been copied in case it's an internal reference, side-stepping
530 // reference invalidation problems without losing the realloc optimization.
531 this->set_size(0);
532 this->grow(NumElts);
533 std::uninitialized_fill_n(this->begin(), NumElts, Elt);
534 this->set_size(NumElts);
535 }
536
537 template <typename... ArgTypes> T &growAndEmplaceBack(ArgTypes &&... Args) {
538 // Use push_back with a copy in case Args has an internal reference,
539 // side-stepping reference invalidation problems without losing the realloc
540 // optimization.
541 push_back(T(std::forward<ArgTypes>(Args)...));
542 return this->back();
543 }
544
545public:
546 void push_back(ValueParamT Elt) {
547 const T *EltPtr = reserveForParamAndGetAddress(Elt);
548 memcpy(reinterpret_cast<void *>(this->end()), EltPtr, sizeof(T));
549 this->set_size(this->size() + 1);
550 }
551
552 void pop_back() { this->set_size(this->size() - 1); }
553};
554
555/// This class consists of common code factored out of the SmallVector class to
556/// reduce code duplication based on the SmallVector 'N' template parameter.
557template <typename T>
558class SmallVectorImpl : public SmallVectorTemplateBase<T> {
559 using SuperClass = SmallVectorTemplateBase<T>;
560
561public:
562 using iterator = typename SuperClass::iterator;
563 using const_iterator = typename SuperClass::const_iterator;
564 using reference = typename SuperClass::reference;
565 using size_type = typename SuperClass::size_type;
566
567protected:
568 using SmallVectorTemplateBase<T>::TakesParamByValue;
569 using ValueParamT = typename SuperClass::ValueParamT;
570
571 // Default ctor - Initialize to empty.
572 explicit SmallVectorImpl(unsigned N)
573 : SmallVectorTemplateBase<T>(N) {}
574
575public:
576 SmallVectorImpl(const SmallVectorImpl &) = delete;
577
578 ~SmallVectorImpl() {
579 // Subclass has already destructed this vector's elements.
580 // If this wasn't grown from the inline copy, deallocate the old space.
581 if (!this->isSmall())
582 free(this->begin());
583 }
584
585 void clear() {
586 this->destroy_range(this->begin(), this->end());
587 this->Size = 0;
588 }
589
590private:
591 template <bool ForOverwrite> void resizeImpl(size_type N) {
592 if (N < this->size()) {
593 this->pop_back_n(this->size() - N);
594 } else if (N > this->size()) {
595 this->reserve(N);
596 for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
597 if (ForOverwrite)
598 new (&*I) T;
599 else
600 new (&*I) T();
601 this->set_size(N);
602 }
603 }
604
605public:
606 void resize(size_type N) { resizeImpl<false>(N); }
607
608 /// Like resize, but \ref T is POD, the new values won't be initialized.
609 void resize_for_overwrite(size_type N) { resizeImpl<true>(N); }
610
611 void resize(size_type N, ValueParamT NV) {
612 if (N == this->size())
613 return;
614
615 if (N < this->size()) {
616 this->pop_back_n(this->size() - N);
617 return;
618 }
619
620 // N > this->size(). Defer to append.
621 this->append(N - this->size(), NV);
622 }
623
624 void reserve(size_type N) {
625 if (this->capacity() < N)
626 this->grow(N);
627 }
628
629 void pop_back_n(size_type NumItems) {
630 assert(this->size() >= NumItems)((void)0);
631 this->destroy_range(this->end() - NumItems, this->end());
632 this->set_size(this->size() - NumItems);
633 }
634
635 LLVM_NODISCARD[[clang::warn_unused_result]] T pop_back_val() {
636 T Result = ::std::move(this->back());
637 this->pop_back();
638 return Result;
639 }
640
641 void swap(SmallVectorImpl &RHS);
642
643 /// Add the specified range to the end of the SmallVector.
644 template <typename in_iter,
645 typename = std::enable_if_t<std::is_convertible<
646 typename std::iterator_traits<in_iter>::iterator_category,
647 std::input_iterator_tag>::value>>
648 void append(in_iter in_start, in_iter in_end) {
649 this->assertSafeToAddRange(in_start, in_end);
650 size_type NumInputs = std::distance(in_start, in_end);
651 this->reserve(this->size() + NumInputs);
652 this->uninitialized_copy(in_start, in_end, this->end());
653 this->set_size(this->size() + NumInputs);
654 }
655
656 /// Append \p NumInputs copies of \p Elt to the end.
657 void append(size_type NumInputs, ValueParamT Elt) {
658 const T *EltPtr = this->reserveForParamAndGetAddress(Elt, NumInputs);
659 std::uninitialized_fill_n(this->end(), NumInputs, *EltPtr);
660 this->set_size(this->size() + NumInputs);
661 }
662
663 void append(std::initializer_list<T> IL) {
664 append(IL.begin(), IL.end());
665 }
666
667 void append(const SmallVectorImpl &RHS) { append(RHS.begin(), RHS.end()); }
668
669 void assign(size_type NumElts, ValueParamT Elt) {
670 // Note that Elt could be an internal reference.
671 if (NumElts > this->capacity()) {
672 this->growAndAssign(NumElts, Elt);
673 return;
674 }
675
676 // Assign over existing elements.
677 std::fill_n(this->begin(), std::min(NumElts, this->size()), Elt);
678 if (NumElts > this->size())
679 std::uninitialized_fill_n(this->end(), NumElts - this->size(), Elt);
680 else if (NumElts < this->size())
681 this->destroy_range(this->begin() + NumElts, this->end());
682 this->set_size(NumElts);
683 }
684
685 // FIXME: Consider assigning over existing elements, rather than clearing &
686 // re-initializing them - for all assign(...) variants.
687
688 template <typename in_iter,
689 typename = std::enable_if_t<std::is_convertible<
690 typename std::iterator_traits<in_iter>::iterator_category,
691 std::input_iterator_tag>::value>>
692 void assign(in_iter in_start, in_iter in_end) {
693 this->assertSafeToReferenceAfterClear(in_start, in_end);
694 clear();
695 append(in_start, in_end);
696 }
697
698 void assign(std::initializer_list<T> IL) {
699 clear();
700 append(IL);
701 }
702
703 void assign(const SmallVectorImpl &RHS) { assign(RHS.begin(), RHS.end()); }
704
705 iterator erase(const_iterator CI) {
706 // Just cast away constness because this is a non-const member function.
707 iterator I = const_cast<iterator>(CI);
708
709 assert(this->isReferenceToStorage(CI) && "Iterator to erase is out of bounds.")((void)0);
710
711 iterator N = I;
712 // Shift all elts down one.
713 std::move(I+1, this->end(), I);
714 // Drop the last elt.
715 this->pop_back();
716 return(N);
717 }
718
719 iterator erase(const_iterator CS, const_iterator CE) {
720 // Just cast away constness because this is a non-const member function.
721 iterator S = const_cast<iterator>(CS);
722 iterator E = const_cast<iterator>(CE);
723
724 assert(this->isRangeInStorage(S, E) && "Range to erase is out of bounds.")((void)0);
725
726 iterator N = S;
727 // Shift all elts down.
728 iterator I = std::move(E, this->end(), S);
729 // Drop the last elts.
730 this->destroy_range(I, this->end());
731 this->set_size(I - this->begin());
732 return(N);
733 }
734
735private:
736 template <class ArgType> iterator insert_one_impl(iterator I, ArgType &&Elt) {
737 // Callers ensure that ArgType is derived from T.
738 static_assert(
739 std::is_same<std::remove_const_t<std::remove_reference_t<ArgType>>,
740 T>::value,
741 "ArgType must be derived from T!");
742
743 if (I == this->end()) { // Important special case for empty vector.
744 this->push_back(::std::forward<ArgType>(Elt));
745 return this->end()-1;
746 }
747
748 assert(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.")((void)0);
749
750 // Grow if necessary.
751 size_t Index = I - this->begin();
752 std::remove_reference_t<ArgType> *EltPtr =
753 this->reserveForParamAndGetAddress(Elt);
754 I = this->begin() + Index;
755
756 ::new ((void*) this->end()) T(::std::move(this->back()));
757 // Push everything else over.
758 std::move_backward(I, this->end()-1, this->end());
759 this->set_size(this->size() + 1);
760
761 // If we just moved the element we're inserting, be sure to update
762 // the reference (never happens if TakesParamByValue).
763 static_assert(!TakesParamByValue || std::is_same<ArgType, T>::value,
764 "ArgType must be 'T' when taking by value!");
765 if (!TakesParamByValue && this->isReferenceToRange(EltPtr, I, this->end()))
766 ++EltPtr;
767
768 *I = ::std::forward<ArgType>(*EltPtr);
769 return I;
770 }
771
772public:
773 iterator insert(iterator I, T &&Elt) {
774 return insert_one_impl(I, this->forward_value_param(std::move(Elt)));
775 }
776
777 iterator insert(iterator I, const T &Elt) {
778 return insert_one_impl(I, this->forward_value_param(Elt));
779 }
780
781 iterator insert(iterator I, size_type NumToInsert, ValueParamT Elt) {
782 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
783 size_t InsertElt = I - this->begin();
784
785 if (I == this->end()) { // Important special case for empty vector.
786 append(NumToInsert, Elt);
787 return this->begin()+InsertElt;
788 }
789
790 assert(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.")((void)0);
791
792 // Ensure there is enough space, and get the (maybe updated) address of
793 // Elt.
794 const T *EltPtr = this->reserveForParamAndGetAddress(Elt, NumToInsert);
795
796 // Uninvalidate the iterator.
797 I = this->begin()+InsertElt;
798
799 // If there are more elements between the insertion point and the end of the
800 // range than there are being inserted, we can use a simple approach to
801 // insertion. Since we already reserved space, we know that this won't
802 // reallocate the vector.
803 if (size_t(this->end()-I) >= NumToInsert) {
804 T *OldEnd = this->end();
805 append(std::move_iterator<iterator>(this->end() - NumToInsert),
806 std::move_iterator<iterator>(this->end()));
807
808 // Copy the existing elements that get replaced.
809 std::move_backward(I, OldEnd-NumToInsert, OldEnd);
810
811 // If we just moved the element we're inserting, be sure to update
812 // the reference (never happens if TakesParamByValue).
813 if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
814 EltPtr += NumToInsert;
815
816 std::fill_n(I, NumToInsert, *EltPtr);
817 return I;
818 }
819
820 // Otherwise, we're inserting more elements than exist already, and we're
821 // not inserting at the end.
822
823 // Move over the elements that we're about to overwrite.
824 T *OldEnd = this->end();
825 this->set_size(this->size() + NumToInsert);
826 size_t NumOverwritten = OldEnd-I;
827 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
828
829 // If we just moved the element we're inserting, be sure to update
830 // the reference (never happens if TakesParamByValue).
831 if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
832 EltPtr += NumToInsert;
833
834 // Replace the overwritten part.
835 std::fill_n(I, NumOverwritten, *EltPtr);
836
837 // Insert the non-overwritten middle part.
838 std::uninitialized_fill_n(OldEnd, NumToInsert - NumOverwritten, *EltPtr);
839 return I;
840 }
841
842 template <typename ItTy,
843 typename = std::enable_if_t<std::is_convertible<
844 typename std::iterator_traits<ItTy>::iterator_category,
845 std::input_iterator_tag>::value>>
846 iterator insert(iterator I, ItTy From, ItTy To) {
847 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
848 size_t InsertElt = I - this->begin();
849
850 if (I == this->end()) { // Important special case for empty vector.
851 append(From, To);
852 return this->begin()+InsertElt;
853 }
854
855 assert(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.")((void)0);
856
857 // Check that the reserve that follows doesn't invalidate the iterators.
858 this->assertSafeToAddRange(From, To);
859
860 size_t NumToInsert = std::distance(From, To);
861
862 // Ensure there is enough space.
863 reserve(this->size() + NumToInsert);
864
865 // Uninvalidate the iterator.
866 I = this->begin()+InsertElt;
867
868 // If there are more elements between the insertion point and the end of the
869 // range than there are being inserted, we can use a simple approach to
870 // insertion. Since we already reserved space, we know that this won't
871 // reallocate the vector.
872 if (size_t(this->end()-I) >= NumToInsert) {
873 T *OldEnd = this->end();
874 append(std::move_iterator<iterator>(this->end() - NumToInsert),
875 std::move_iterator<iterator>(this->end()));
876
877 // Copy the existing elements that get replaced.
878 std::move_backward(I, OldEnd-NumToInsert, OldEnd);
879
880 std::copy(From, To, I);
881 return I;
882 }
883
884 // Otherwise, we're inserting more elements than exist already, and we're
885 // not inserting at the end.
886
887 // Move over the elements that we're about to overwrite.
888 T *OldEnd = this->end();
889 this->set_size(this->size() + NumToInsert);
890 size_t NumOverwritten = OldEnd-I;
891 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
892
893 // Replace the overwritten part.
894 for (T *J = I; NumOverwritten > 0; --NumOverwritten) {
895 *J = *From;
896 ++J; ++From;
897 }
898
899 // Insert the non-overwritten middle part.
900 this->uninitialized_copy(From, To, OldEnd);
901 return I;
902 }
903
904 void insert(iterator I, std::initializer_list<T> IL) {
905 insert(I, IL.begin(), IL.end());
906 }
907
908 template <typename... ArgTypes> reference emplace_back(ArgTypes &&... Args) {
909 if (LLVM_UNLIKELY(this->size() >= this->capacity())__builtin_expect((bool)(this->size() >= this->capacity
()), false)
)
910 return this->growAndEmplaceBack(std::forward<ArgTypes>(Args)...);
911
912 ::new ((void *)this->end()) T(std::forward<ArgTypes>(Args)...);
913 this->set_size(this->size() + 1);
914 return this->back();
915 }
916
917 SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
918
919 SmallVectorImpl &operator=(SmallVectorImpl &&RHS);
920
921 bool operator==(const SmallVectorImpl &RHS) const {
922 if (this->size() != RHS.size()) return false;
923 return std::equal(this->begin(), this->end(), RHS.begin());
924 }
925 bool operator!=(const SmallVectorImpl &RHS) const {
926 return !(*this == RHS);
927 }
928
929 bool operator<(const SmallVectorImpl &RHS) const {
930 return std::lexicographical_compare(this->begin(), this->end(),
931 RHS.begin(), RHS.end());
932 }
933};
934
935template <typename T>
936void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
937 if (this == &RHS) return;
938
939 // We can only avoid copying elements if neither vector is small.
940 if (!this->isSmall() && !RHS.isSmall()) {
941 std::swap(this->BeginX, RHS.BeginX);
942 std::swap(this->Size, RHS.Size);
943 std::swap(this->Capacity, RHS.Capacity);
944 return;
945 }
946 this->reserve(RHS.size());
947 RHS.reserve(this->size());
948
949 // Swap the shared elements.
950 size_t NumShared = this->size();
951 if (NumShared > RHS.size()) NumShared = RHS.size();
952 for (size_type i = 0; i != NumShared; ++i)
953 std::swap((*this)[i], RHS[i]);
954
955 // Copy over the extra elts.
956 if (this->size() > RHS.size()) {
957 size_t EltDiff = this->size() - RHS.size();
958 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
959 RHS.set_size(RHS.size() + EltDiff);
960 this->destroy_range(this->begin()+NumShared, this->end());
961 this->set_size(NumShared);
962 } else if (RHS.size() > this->size()) {
963 size_t EltDiff = RHS.size() - this->size();
964 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
965 this->set_size(this->size() + EltDiff);
966 this->destroy_range(RHS.begin()+NumShared, RHS.end());
967 RHS.set_size(NumShared);
968 }
969}
970
971template <typename T>
972SmallVectorImpl<T> &SmallVectorImpl<T>::
973 operator=(const SmallVectorImpl<T> &RHS) {
974 // Avoid self-assignment.
975 if (this == &RHS) return *this;
976
977 // If we already have sufficient space, assign the common elements, then
978 // destroy any excess.
979 size_t RHSSize = RHS.size();
980 size_t CurSize = this->size();
981 if (CurSize >= RHSSize) {
982 // Assign common elements.
983 iterator NewEnd;
984 if (RHSSize)
985 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
986 else
987 NewEnd = this->begin();
988
989 // Destroy excess elements.
990 this->destroy_range(NewEnd, this->end());
991
992 // Trim.
993 this->set_size(RHSSize);
994 return *this;
995 }
996
997 // If we have to grow to have enough elements, destroy the current elements.
998 // This allows us to avoid copying them during the grow.
999 // FIXME: don't do this if they're efficiently moveable.
1000 if (this->capacity() < RHSSize) {
1001 // Destroy current elements.
1002 this->clear();
1003 CurSize = 0;
1004 this->grow(RHSSize);
1005 } else if (CurSize) {
1006 // Otherwise, use assignment for the already-constructed elements.
1007 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
1008 }
1009
1010 // Copy construct the new elements in place.
1011 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
1012 this->begin()+CurSize);
1013
1014 // Set end.
1015 this->set_size(RHSSize);
1016 return *this;
1017}
1018
1019template <typename T>
1020SmallVectorImpl<T> &SmallVectorImpl<T>::operator=(SmallVectorImpl<T> &&RHS) {
1021 // Avoid self-assignment.
1022 if (this == &RHS) return *this;
1023
1024 // If the RHS isn't small, clear this vector and then steal its buffer.
1025 if (!RHS.isSmall()) {
1026 this->destroy_range(this->begin(), this->end());
1027 if (!this->isSmall()) free(this->begin());
1028 this->BeginX = RHS.BeginX;
1029 this->Size = RHS.Size;
1030 this->Capacity = RHS.Capacity;
1031 RHS.resetToSmall();
1032 return *this;
1033 }
1034
1035 // If we already have sufficient space, assign the common elements, then
1036 // destroy any excess.
1037 size_t RHSSize = RHS.size();
1038 size_t CurSize = this->size();
1039 if (CurSize >= RHSSize) {
1040 // Assign common elements.
1041 iterator NewEnd = this->begin();
1042 if (RHSSize)
1043 NewEnd = std::move(RHS.begin(), RHS.end(), NewEnd);
1044
1045 // Destroy excess elements and trim the bounds.
1046 this->destroy_range(NewEnd, this->end());
1047 this->set_size(RHSSize);
1048
1049 // Clear the RHS.
1050 RHS.clear();
1051
1052 return *this;
1053 }
1054
1055 // If we have to grow to have enough elements, destroy the current elements.
1056 // This allows us to avoid copying them during the grow.
1057 // FIXME: this may not actually make any sense if we can efficiently move
1058 // elements.
1059 if (this->capacity() < RHSSize) {
1060 // Destroy current elements.
1061 this->clear();
1062 CurSize = 0;
1063 this->grow(RHSSize);
1064 } else if (CurSize) {
1065 // Otherwise, use assignment for the already-constructed elements.
1066 std::move(RHS.begin(), RHS.begin()+CurSize, this->begin());
1067 }
1068
1069 // Move-construct the new elements in place.
1070 this->uninitialized_move(RHS.begin()+CurSize, RHS.end(),
1071 this->begin()+CurSize);
1072
1073 // Set end.
1074 this->set_size(RHSSize);
1075
1076 RHS.clear();
1077 return *this;
1078}
1079
1080/// Storage for the SmallVector elements. This is specialized for the N=0 case
1081/// to avoid allocating unnecessary storage.
1082template <typename T, unsigned N>
1083struct SmallVectorStorage {
1084 alignas(T) char InlineElts[N * sizeof(T)];
1085};
1086
1087/// We need the storage to be properly aligned even for small-size of 0 so that
1088/// the pointer math in \a SmallVectorTemplateCommon::getFirstEl() is
1089/// well-defined.
1090template <typename T> struct alignas(T) SmallVectorStorage<T, 0> {};
1091
1092/// Forward declaration of SmallVector so that
1093/// calculateSmallVectorDefaultInlinedElements can reference
1094/// `sizeof(SmallVector<T, 0>)`.
1095template <typename T, unsigned N> class LLVM_GSL_OWNER[[gsl::Owner]] SmallVector;
1096
1097/// Helper class for calculating the default number of inline elements for
1098/// `SmallVector<T>`.
1099///
1100/// This should be migrated to a constexpr function when our minimum
1101/// compiler support is enough for multi-statement constexpr functions.
1102template <typename T> struct CalculateSmallVectorDefaultInlinedElements {
1103 // Parameter controlling the default number of inlined elements
1104 // for `SmallVector<T>`.
1105 //
1106 // The default number of inlined elements ensures that
1107 // 1. There is at least one inlined element.
1108 // 2. `sizeof(SmallVector<T>) <= kPreferredSmallVectorSizeof` unless
1109 // it contradicts 1.
1110 static constexpr size_t kPreferredSmallVectorSizeof = 64;
1111
1112 // static_assert that sizeof(T) is not "too big".
1113 //
1114 // Because our policy guarantees at least one inlined element, it is possible
1115 // for an arbitrarily large inlined element to allocate an arbitrarily large
1116 // amount of inline storage. We generally consider it an antipattern for a
1117 // SmallVector to allocate an excessive amount of inline storage, so we want
1118 // to call attention to these cases and make sure that users are making an
1119 // intentional decision if they request a lot of inline storage.
1120 //
1121 // We want this assertion to trigger in pathological cases, but otherwise
1122 // not be too easy to hit. To accomplish that, the cutoff is actually somewhat
1123 // larger than kPreferredSmallVectorSizeof (otherwise,
1124 // `SmallVector<SmallVector<T>>` would be one easy way to trip it, and that
1125 // pattern seems useful in practice).
1126 //
1127 // One wrinkle is that this assertion is in theory non-portable, since
1128 // sizeof(T) is in general platform-dependent. However, we don't expect this
1129 // to be much of an issue, because most LLVM development happens on 64-bit
1130 // hosts, and therefore sizeof(T) is expected to *decrease* when compiled for
1131 // 32-bit hosts, dodging the issue. The reverse situation, where development
1132 // happens on a 32-bit host and then fails due to sizeof(T) *increasing* on a
1133 // 64-bit host, is expected to be very rare.
1134 static_assert(
1135 sizeof(T) <= 256,
1136 "You are trying to use a default number of inlined elements for "
1137 "`SmallVector<T>` but `sizeof(T)` is really big! Please use an "
1138 "explicit number of inlined elements with `SmallVector<T, N>` to make "
1139 "sure you really want that much inline storage.");
1140
1141 // Discount the size of the header itself when calculating the maximum inline
1142 // bytes.
1143 static constexpr size_t PreferredInlineBytes =
1144 kPreferredSmallVectorSizeof - sizeof(SmallVector<T, 0>);
1145 static constexpr size_t NumElementsThatFit = PreferredInlineBytes / sizeof(T);
1146 static constexpr size_t value =
1147 NumElementsThatFit == 0 ? 1 : NumElementsThatFit;
1148};
1149
1150/// This is a 'vector' (really, a variable-sized array), optimized
1151/// for the case when the array is small. It contains some number of elements
1152/// in-place, which allows it to avoid heap allocation when the actual number of
1153/// elements is below that threshold. This allows normal "small" cases to be
1154/// fast without losing generality for large inputs.
1155///
1156/// \note
1157/// In the absence of a well-motivated choice for the number of inlined
1158/// elements \p N, it is recommended to use \c SmallVector<T> (that is,
1159/// omitting the \p N). This will choose a default number of inlined elements
1160/// reasonable for allocation on the stack (for example, trying to keep \c
1161/// sizeof(SmallVector<T>) around 64 bytes).
1162///
1163/// \warning This does not attempt to be exception safe.
1164///
1165/// \see https://llvm.org/docs/ProgrammersManual.html#llvm-adt-smallvector-h
1166template <typename T,
1167 unsigned N = CalculateSmallVectorDefaultInlinedElements<T>::value>
1168class LLVM_GSL_OWNER[[gsl::Owner]] SmallVector : public SmallVectorImpl<T>,
1169 SmallVectorStorage<T, N> {
1170public:
1171 SmallVector() : SmallVectorImpl<T>(N) {}
1172
1173 ~SmallVector() {
1174 // Destroy the constructed elements in the vector.
1175 this->destroy_range(this->begin(), this->end());
1176 }
1177
1178 explicit SmallVector(size_t Size, const T &Value = T())
1179 : SmallVectorImpl<T>(N) {
1180 this->assign(Size, Value);
1181 }
1182
1183 template <typename ItTy,
1184 typename = std::enable_if_t<std::is_convertible<
1185 typename std::iterator_traits<ItTy>::iterator_category,
1186 std::input_iterator_tag>::value>>
1187 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
1188 this->append(S, E);
1189 }
1190
1191 template <typename RangeTy>
1192 explicit SmallVector(const iterator_range<RangeTy> &R)
1193 : SmallVectorImpl<T>(N) {
1194 this->append(R.begin(), R.end());
1195 }
1196
1197 SmallVector(std::initializer_list<T> IL) : SmallVectorImpl<T>(N) {
1198 this->assign(IL);
1199 }
1200
1201 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(N) {
1202 if (!RHS.empty())
1203 SmallVectorImpl<T>::operator=(RHS);
1204 }
1205
1206 SmallVector &operator=(const SmallVector &RHS) {
1207 SmallVectorImpl<T>::operator=(RHS);
1208 return *this;
1209 }
1210
1211 SmallVector(SmallVector &&RHS) : SmallVectorImpl<T>(N) {
1212 if (!RHS.empty())
1213 SmallVectorImpl<T>::operator=(::std::move(RHS));
1214 }
1215
1216 SmallVector(SmallVectorImpl<T> &&RHS) : SmallVectorImpl<T>(N) {
1217 if (!RHS.empty())
1218 SmallVectorImpl<T>::operator=(::std::move(RHS));
1219 }
1220
1221 SmallVector &operator=(SmallVector &&RHS) {
1222 SmallVectorImpl<T>::operator=(::std::move(RHS));
1223 return *this;
1224 }
1225
1226 SmallVector &operator=(SmallVectorImpl<T> &&RHS) {
1227 SmallVectorImpl<T>::operator=(::std::move(RHS));
1228 return *this;
1229 }
1230
1231 SmallVector &operator=(std::initializer_list<T> IL) {
1232 this->assign(IL);
1233 return *this;
1234 }
1235};
1236
1237template <typename T, unsigned N>
1238inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
1239 return X.capacity_in_bytes();
1240}
1241
1242/// Given a range of type R, iterate the entire range and return a
1243/// SmallVector with elements of the vector. This is useful, for example,
1244/// when you want to iterate a range and then sort the results.
1245template <unsigned Size, typename R>
1246SmallVector<typename std::remove_const<typename std::remove_reference<
1247 decltype(*std::begin(std::declval<R &>()))>::type>::type,
1248 Size>
1249to_vector(R &&Range) {
1250 return {std::begin(Range), std::end(Range)};
1251}
1252
1253} // end namespace llvm
1254
1255namespace std {
1256
1257 /// Implement std::swap in terms of SmallVector swap.
1258 template<typename T>
1259 inline void
1260 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
1261 LHS.swap(RHS);
1262 }
1263
1264 /// Implement std::swap in terms of SmallVector swap.
1265 template<typename T, unsigned N>
1266 inline void
1267 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {
1268 LHS.swap(RHS);
1269 }
1270
1271} // end namespace std
1272
1273#endif // LLVM_ADT_SMALLVECTOR_H