Bug Summary

File:lib/Analysis/MemorySSA.cpp
Warning:line 834, column 37
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -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 -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-8/lib/clang/8.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn345461/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/8.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-8/lib/clang/8.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/lib/Analysis -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-10-27-211344-32123-1 -x c++ /build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp -faddrsig
1//===- MemorySSA.cpp - Memory SSA Builder ---------------------------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the MemorySSA class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Analysis/MemorySSA.h"
15#include "llvm/ADT/DenseMap.h"
16#include "llvm/ADT/DenseMapInfo.h"
17#include "llvm/ADT/DenseSet.h"
18#include "llvm/ADT/DepthFirstIterator.h"
19#include "llvm/ADT/Hashing.h"
20#include "llvm/ADT/None.h"
21#include "llvm/ADT/Optional.h"
22#include "llvm/ADT/STLExtras.h"
23#include "llvm/ADT/SmallPtrSet.h"
24#include "llvm/ADT/SmallVector.h"
25#include "llvm/ADT/iterator.h"
26#include "llvm/ADT/iterator_range.h"
27#include "llvm/Analysis/AliasAnalysis.h"
28#include "llvm/Analysis/IteratedDominanceFrontier.h"
29#include "llvm/Analysis/MemoryLocation.h"
30#include "llvm/Config/llvm-config.h"
31#include "llvm/IR/AssemblyAnnotationWriter.h"
32#include "llvm/IR/BasicBlock.h"
33#include "llvm/IR/CallSite.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/Pass.h"
44#include "llvm/Support/AtomicOrdering.h"
45#include "llvm/Support/Casting.h"
46#include "llvm/Support/CommandLine.h"
47#include "llvm/Support/Compiler.h"
48#include "llvm/Support/Debug.h"
49#include "llvm/Support/ErrorHandling.h"
50#include "llvm/Support/FormattedStream.h"
51#include "llvm/Support/raw_ostream.h"
52#include <algorithm>
53#include <cassert>
54#include <iterator>
55#include <memory>
56#include <utility>
57
58using namespace llvm;
59
60#define DEBUG_TYPE"memoryssa" "memoryssa"
61
62INITIALIZE_PASS_BEGIN(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
&Registry) {
63 true)static void *initializeMemorySSAWrapperPassPassOnce(PassRegistry
&Registry) {
64INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
65INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)initializeAAResultsWrapperPassPass(Registry);
66INITIALIZE_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))
; }
67 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))
; }
68
69INITIALIZE_PASS_BEGIN(MemorySSAPrinterLegacyPass, "print-memoryssa",static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
&Registry) {
70 "Memory SSA Printer", false, false)static void *initializeMemorySSAPrinterLegacyPassPassOnce(PassRegistry
&Registry) {
71INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)initializeMemorySSAWrapperPassPass(Registry);
72INITIALIZE_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
)); }
73 "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
)); }
74
75static cl::opt<unsigned> MaxCheckLimit(
76 "memssa-check-limit", cl::Hidden, cl::init(100),
77 cl::desc("The maximum number of stores/phis MemorySSA"
78 "will consider trying to walk past (default = 100)"));
79
80// Always verify MemorySSA if expensive checking is enabled.
81#ifdef EXPENSIVE_CHECKS
82bool llvm::VerifyMemorySSA = true;
83#else
84bool llvm::VerifyMemorySSA = false;
85#endif
86static cl::opt<bool, true>
87 VerifyMemorySSAX("verify-memoryssa", cl::location(VerifyMemorySSA),
88 cl::Hidden, cl::desc("Enable verification of MemorySSA."));
89
90namespace llvm {
91
92/// An assembly annotator class to print Memory SSA information in
93/// comments.
94class MemorySSAAnnotatedWriter : public AssemblyAnnotationWriter {
95 friend class MemorySSA;
96
97 const MemorySSA *MSSA;
98
99public:
100 MemorySSAAnnotatedWriter(const MemorySSA *M) : MSSA(M) {}
101
102 void emitBasicBlockStartAnnot(const BasicBlock *BB,
103 formatted_raw_ostream &OS) override {
104 if (MemoryAccess *MA = MSSA->getMemoryAccess(BB))
105 OS << "; " << *MA << "\n";
106 }
107
108 void emitInstructionAnnot(const Instruction *I,
109 formatted_raw_ostream &OS) override {
110 if (MemoryAccess *MA = MSSA->getMemoryAccess(I))
111 OS << "; " << *MA << "\n";
112 }
113};
114
115} // end namespace llvm
116
117namespace {
118
119/// Our current alias analysis API differentiates heavily between calls and
120/// non-calls, and functions called on one usually assert on the other.
121/// This class encapsulates the distinction to simplify other code that wants
122/// "Memory affecting instructions and related data" to use as a key.
123/// For example, this class is used as a densemap key in the use optimizer.
124class MemoryLocOrCall {
125public:
126 bool IsCall = false;
127
128 MemoryLocOrCall(MemoryUseOrDef *MUD)
129 : MemoryLocOrCall(MUD->getMemoryInst()) {}
130 MemoryLocOrCall(const MemoryUseOrDef *MUD)
131 : MemoryLocOrCall(MUD->getMemoryInst()) {}
132
133 MemoryLocOrCall(Instruction *Inst) {
134 if (ImmutableCallSite(Inst)) {
135 IsCall = true;
136 CS = ImmutableCallSite(Inst);
137 } else {
138 IsCall = false;
139 // There is no such thing as a memorylocation for a fence inst, and it is
140 // unique in that regard.
141 if (!isa<FenceInst>(Inst))
142 Loc = MemoryLocation::get(Inst);
143 }
144 }
145
146 explicit MemoryLocOrCall(const MemoryLocation &Loc) : Loc(Loc) {}
147
148 ImmutableCallSite getCS() const {
149 assert(IsCall)((IsCall) ? static_cast<void> (0) : __assert_fail ("IsCall"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 149, __PRETTY_FUNCTION__))
;
150 return CS;
151 }
152
153 MemoryLocation getLoc() const {
154 assert(!IsCall)((!IsCall) ? static_cast<void> (0) : __assert_fail ("!IsCall"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 154, __PRETTY_FUNCTION__))
;
155 return Loc;
156 }
157
158 bool operator==(const MemoryLocOrCall &Other) const {
159 if (IsCall != Other.IsCall)
160 return false;
161
162 if (!IsCall)
163 return Loc == Other.Loc;
164
165 if (CS.getCalledValue() != Other.CS.getCalledValue())
166 return false;
167
168 return CS.arg_size() == Other.CS.arg_size() &&
169 std::equal(CS.arg_begin(), CS.arg_end(), Other.CS.arg_begin());
170 }
171
172private:
173 union {
174 ImmutableCallSite CS;
175 MemoryLocation Loc;
176 };
177};
178
179} // end anonymous namespace
180
181namespace llvm {
182
183template <> struct DenseMapInfo<MemoryLocOrCall> {
184 static inline MemoryLocOrCall getEmptyKey() {
185 return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getEmptyKey());
186 }
187
188 static inline MemoryLocOrCall getTombstoneKey() {
189 return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getTombstoneKey());
190 }
191
192 static unsigned getHashValue(const MemoryLocOrCall &MLOC) {
193 if (!MLOC.IsCall)
194 return hash_combine(
195 MLOC.IsCall,
196 DenseMapInfo<MemoryLocation>::getHashValue(MLOC.getLoc()));
197
198 hash_code hash =
199 hash_combine(MLOC.IsCall, DenseMapInfo<const Value *>::getHashValue(
200 MLOC.getCS().getCalledValue()));
201
202 for (const Value *Arg : MLOC.getCS().args())
203 hash = hash_combine(hash, DenseMapInfo<const Value *>::getHashValue(Arg));
204 return hash;
205 }
206
207 static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) {
208 return LHS == RHS;
209 }
210};
211
212} // end namespace llvm
213
214/// This does one-way checks to see if Use could theoretically be hoisted above
215/// MayClobber. This will not check the other way around.
216///
217/// This assumes that, for the purposes of MemorySSA, Use comes directly after
218/// MayClobber, with no potentially clobbering operations in between them.
219/// (Where potentially clobbering ops are memory barriers, aliased stores, etc.)
220static bool areLoadsReorderable(const LoadInst *Use,
221 const LoadInst *MayClobber) {
222 bool VolatileUse = Use->isVolatile();
223 bool VolatileClobber = MayClobber->isVolatile();
224 // Volatile operations may never be reordered with other volatile operations.
225 if (VolatileUse && VolatileClobber)
226 return false;
227 // Otherwise, volatile doesn't matter here. From the language reference:
228 // 'optimizers may change the order of volatile operations relative to
229 // non-volatile operations.'"
230
231 // If a load is seq_cst, it cannot be moved above other loads. If its ordering
232 // is weaker, it can be moved above other loads. We just need to be sure that
233 // MayClobber isn't an acquire load, because loads can't be moved above
234 // acquire loads.
235 //
236 // Note that this explicitly *does* allow the free reordering of monotonic (or
237 // weaker) loads of the same address.
238 bool SeqCstUse = Use->getOrdering() == AtomicOrdering::SequentiallyConsistent;
239 bool MayClobberIsAcquire = isAtLeastOrStrongerThan(MayClobber->getOrdering(),
240 AtomicOrdering::Acquire);
241 return !(SeqCstUse || MayClobberIsAcquire);
242}
243
244namespace {
245
246struct ClobberAlias {
247 bool IsClobber;
248 Optional<AliasResult> AR;
249};
250
251} // end anonymous namespace
252
253// Return a pair of {IsClobber (bool), AR (AliasResult)}. It relies on AR being
254// ignored if IsClobber = false.
255static ClobberAlias instructionClobbersQuery(const MemoryDef *MD,
256 const MemoryLocation &UseLoc,
257 const Instruction *UseInst,
258 AliasAnalysis &AA) {
259 Instruction *DefInst = MD->getMemoryInst();
260 assert(DefInst && "Defining instruction not actually an instruction")((DefInst && "Defining instruction not actually an instruction"
) ? static_cast<void> (0) : __assert_fail ("DefInst && \"Defining instruction not actually an instruction\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 260, __PRETTY_FUNCTION__))
;
261 ImmutableCallSite UseCS(UseInst);
262 Optional<AliasResult> AR;
263
264 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(DefInst)) {
265 // These intrinsics will show up as affecting memory, but they are just
266 // markers, mostly.
267 //
268 // FIXME: We probably don't actually want MemorySSA to model these at all
269 // (including creating MemoryAccesses for them): we just end up inventing
270 // clobbers where they don't really exist at all. Please see D43269 for
271 // context.
272 switch (II->getIntrinsicID()) {
273 case Intrinsic::lifetime_start:
274 if (UseCS)
275 return {false, NoAlias};
276 AR = AA.alias(MemoryLocation(II->getArgOperand(1)), UseLoc);
277 return {AR != NoAlias, AR};
278 case Intrinsic::lifetime_end:
279 case Intrinsic::invariant_start:
280 case Intrinsic::invariant_end:
281 case Intrinsic::assume:
282 return {false, NoAlias};
283 default:
284 break;
285 }
286 }
287
288 if (UseCS) {
289 ModRefInfo I = AA.getModRefInfo(DefInst, UseCS);
290 AR = isMustSet(I) ? MustAlias : MayAlias;
291 return {isModOrRefSet(I), AR};
292 }
293
294 if (auto *DefLoad = dyn_cast<LoadInst>(DefInst))
295 if (auto *UseLoad = dyn_cast<LoadInst>(UseInst))
296 return {!areLoadsReorderable(UseLoad, DefLoad), MayAlias};
297
298 ModRefInfo I = AA.getModRefInfo(DefInst, UseLoc);
299 AR = isMustSet(I) ? MustAlias : MayAlias;
300 return {isModSet(I), AR};
301}
302
303static ClobberAlias instructionClobbersQuery(MemoryDef *MD,
304 const MemoryUseOrDef *MU,
305 const MemoryLocOrCall &UseMLOC,
306 AliasAnalysis &AA) {
307 // FIXME: This is a temporary hack to allow a single instructionClobbersQuery
308 // to exist while MemoryLocOrCall is pushed through places.
309 if (UseMLOC.IsCall)
310 return instructionClobbersQuery(MD, MemoryLocation(), MU->getMemoryInst(),
311 AA);
312 return instructionClobbersQuery(MD, UseMLOC.getLoc(), MU->getMemoryInst(),
313 AA);
314}
315
316// Return true when MD may alias MU, return false otherwise.
317bool MemorySSAUtil::defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU,
318 AliasAnalysis &AA) {
319 return instructionClobbersQuery(MD, MU, MemoryLocOrCall(MU), AA).IsClobber;
320}
321
322namespace {
323
324struct UpwardsMemoryQuery {
325 // True if our original query started off as a call
326 bool IsCall = false;
327 // The pointer location we started the query with. This will be empty if
328 // IsCall is true.
329 MemoryLocation StartingLoc;
330 // This is the instruction we were querying about.
331 const Instruction *Inst = nullptr;
332 // The MemoryAccess we actually got called with, used to test local domination
333 const MemoryAccess *OriginalAccess = nullptr;
334 Optional<AliasResult> AR = MayAlias;
335
336 UpwardsMemoryQuery() = default;
337
338 UpwardsMemoryQuery(const Instruction *Inst, const MemoryAccess *Access)
339 : IsCall(ImmutableCallSite(Inst)), Inst(Inst), OriginalAccess(Access) {
340 if (!IsCall)
341 StartingLoc = MemoryLocation::get(Inst);
342 }
343};
344
345} // end anonymous namespace
346
347static bool lifetimeEndsAt(MemoryDef *MD, const MemoryLocation &Loc,
348 AliasAnalysis &AA) {
349 Instruction *Inst = MD->getMemoryInst();
350 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
351 switch (II->getIntrinsicID()) {
352 case Intrinsic::lifetime_end:
353 return AA.isMustAlias(MemoryLocation(II->getArgOperand(1)), Loc);
354 default:
355 return false;
356 }
357 }
358 return false;
359}
360
361static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysis &AA,
362 const Instruction *I) {
363 // If the memory can't be changed, then loads of the memory can't be
364 // clobbered.
365 return isa<LoadInst>(I) && (I->getMetadata(LLVMContext::MD_invariant_load) ||
366 AA.pointsToConstantMemory(cast<LoadInst>(I)->
367 getPointerOperand()));
368}
369
370/// Verifies that `Start` is clobbered by `ClobberAt`, and that nothing
371/// inbetween `Start` and `ClobberAt` can clobbers `Start`.
372///
373/// This is meant to be as simple and self-contained as possible. Because it
374/// uses no cache, etc., it can be relatively expensive.
375///
376/// \param Start The MemoryAccess that we want to walk from.
377/// \param ClobberAt A clobber for Start.
378/// \param StartLoc The MemoryLocation for Start.
379/// \param MSSA The MemorySSA instance that Start and ClobberAt belong to.
380/// \param Query The UpwardsMemoryQuery we used for our search.
381/// \param AA The AliasAnalysis we used for our search.
382/// \param AllowImpreciseClobber Always false, unless we do relaxed verify.
383static void
384checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt,
385 const MemoryLocation &StartLoc, const MemorySSA &MSSA,
386 const UpwardsMemoryQuery &Query, AliasAnalysis &AA,
387 bool AllowImpreciseClobber = false) {
388 assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?")((MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?"
) ? static_cast<void> (0) : __assert_fail ("MSSA.dominates(ClobberAt, Start) && \"Clobber doesn't dominate start?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 388, __PRETTY_FUNCTION__))
;
389
390 if (MSSA.isLiveOnEntryDef(Start)) {
391 assert(MSSA.isLiveOnEntryDef(ClobberAt) &&((MSSA.isLiveOnEntryDef(ClobberAt) && "liveOnEntry must clobber itself"
) ? static_cast<void> (0) : __assert_fail ("MSSA.isLiveOnEntryDef(ClobberAt) && \"liveOnEntry must clobber itself\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 392, __PRETTY_FUNCTION__))
392 "liveOnEntry must clobber itself")((MSSA.isLiveOnEntryDef(ClobberAt) && "liveOnEntry must clobber itself"
) ? static_cast<void> (0) : __assert_fail ("MSSA.isLiveOnEntryDef(ClobberAt) && \"liveOnEntry must clobber itself\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 392, __PRETTY_FUNCTION__))
;
393 return;
394 }
395
396 bool FoundClobber = false;
397 DenseSet<ConstMemoryAccessPair> VisitedPhis;
398 SmallVector<ConstMemoryAccessPair, 8> Worklist;
399 Worklist.emplace_back(Start, StartLoc);
400 // Walk all paths from Start to ClobberAt, while looking for clobbers. If one
401 // is found, complain.
402 while (!Worklist.empty()) {
403 auto MAP = Worklist.pop_back_val();
404 // All we care about is that nothing from Start to ClobberAt clobbers Start.
405 // We learn nothing from revisiting nodes.
406 if (!VisitedPhis.insert(MAP).second)
407 continue;
408
409 for (const auto *MA : def_chain(MAP.first)) {
410 if (MA == ClobberAt) {
411 if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
412 // instructionClobbersQuery isn't essentially free, so don't use `|=`,
413 // since it won't let us short-circuit.
414 //
415 // Also, note that this can't be hoisted out of the `Worklist` loop,
416 // since MD may only act as a clobber for 1 of N MemoryLocations.
417 FoundClobber = FoundClobber || MSSA.isLiveOnEntryDef(MD);
418 if (!FoundClobber) {
419 ClobberAlias CA =
420 instructionClobbersQuery(MD, MAP.second, Query.Inst, AA);
421 if (CA.IsClobber) {
422 FoundClobber = true;
423 // Not used: CA.AR;
424 }
425 }
426 }
427 break;
428 }
429
430 // We should never hit liveOnEntry, unless it's the clobber.
431 assert(!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?")((!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(MA) && \"Hit liveOnEntry before clobber?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 431, __PRETTY_FUNCTION__))
;
432
433 if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
434 // If Start is a Def, skip self.
435 if (MD == Start)
436 continue;
437
438 assert(!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA)((!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .
IsClobber && "Found clobber before reaching ClobberAt!"
) ? static_cast<void> (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .IsClobber && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 440, __PRETTY_FUNCTION__))
439 .IsClobber &&((!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .
IsClobber && "Found clobber before reaching ClobberAt!"
) ? static_cast<void> (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .IsClobber && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 440, __PRETTY_FUNCTION__))
440 "Found clobber before reaching ClobberAt!")((!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .
IsClobber && "Found clobber before reaching ClobberAt!"
) ? static_cast<void> (0) : __assert_fail ("!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA) .IsClobber && \"Found clobber before reaching ClobberAt!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 440, __PRETTY_FUNCTION__))
;
441 continue;
442 }
443
444 if (const auto *MU = dyn_cast<MemoryUse>(MA)) {
445 (void)MU;
446 assert (MU == Start &&((MU == Start && "Can only find use in def chain if Start is a use"
) ? static_cast<void> (0) : __assert_fail ("MU == Start && \"Can only find use in def chain if Start is a use\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 447, __PRETTY_FUNCTION__))
447 "Can only find use in def chain if Start is a use")((MU == Start && "Can only find use in def chain if Start is a use"
) ? static_cast<void> (0) : __assert_fail ("MU == Start && \"Can only find use in def chain if Start is a use\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 447, __PRETTY_FUNCTION__))
;
448 continue;
449 }
450
451 assert(isa<MemoryPhi>(MA))((isa<MemoryPhi>(MA)) ? static_cast<void> (0) : __assert_fail
("isa<MemoryPhi>(MA)", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 451, __PRETTY_FUNCTION__))
;
452 Worklist.append(
453 upward_defs_begin({const_cast<MemoryAccess *>(MA), MAP.second}),
454 upward_defs_end());
455 }
456 }
457
458 // If the verify is done following an optimization, it's possible that
459 // ClobberAt was a conservative clobbering, that we can now infer is not a
460 // true clobbering access. Don't fail the verify if that's the case.
461 // We do have accesses that claim they're optimized, but could be optimized
462 // further. Updating all these can be expensive, so allow it for now (FIXME).
463 if (AllowImpreciseClobber)
464 return;
465
466 // If ClobberAt is a MemoryPhi, we can assume something above it acted as a
467 // clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point.
468 assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&(((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&
"ClobberAt never acted as a clobber") ? static_cast<void>
(0) : __assert_fail ("(isa<MemoryPhi>(ClobberAt) || FoundClobber) && \"ClobberAt never acted as a clobber\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 469, __PRETTY_FUNCTION__))
469 "ClobberAt never acted as a clobber")(((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&
"ClobberAt never acted as a clobber") ? static_cast<void>
(0) : __assert_fail ("(isa<MemoryPhi>(ClobberAt) || FoundClobber) && \"ClobberAt never acted as a clobber\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 469, __PRETTY_FUNCTION__))
;
470}
471
472namespace {
473
474/// Our algorithm for walking (and trying to optimize) clobbers, all wrapped up
475/// in one class.
476class ClobberWalker {
477 /// Save a few bytes by using unsigned instead of size_t.
478 using ListIndex = unsigned;
479
480 /// Represents a span of contiguous MemoryDefs, potentially ending in a
481 /// MemoryPhi.
482 struct DefPath {
483 MemoryLocation Loc;
484 // Note that, because we always walk in reverse, Last will always dominate
485 // First. Also note that First and Last are inclusive.
486 MemoryAccess *First;
487 MemoryAccess *Last;
488 Optional<ListIndex> Previous;
489
490 DefPath(const MemoryLocation &Loc, MemoryAccess *First, MemoryAccess *Last,
491 Optional<ListIndex> Previous)
492 : Loc(Loc), First(First), Last(Last), Previous(Previous) {}
493
494 DefPath(const MemoryLocation &Loc, MemoryAccess *Init,
495 Optional<ListIndex> Previous)
496 : DefPath(Loc, Init, Init, Previous) {}
497 };
498
499 const MemorySSA &MSSA;
500 AliasAnalysis &AA;
501 DominatorTree &DT;
502 UpwardsMemoryQuery *Query;
503
504 // Phi optimization bookkeeping
505 SmallVector<DefPath, 32> Paths;
506 DenseSet<ConstMemoryAccessPair> VisitedPhis;
507
508 /// Find the nearest def or phi that `From` can legally be optimized to.
509 const MemoryAccess *getWalkTarget(const MemoryPhi *From) const {
510 assert(From->getNumOperands() && "Phi with no operands?")((From->getNumOperands() && "Phi with no operands?"
) ? static_cast<void> (0) : __assert_fail ("From->getNumOperands() && \"Phi with no operands?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 510, __PRETTY_FUNCTION__))
;
511
512 BasicBlock *BB = From->getBlock();
513 MemoryAccess *Result = MSSA.getLiveOnEntryDef();
514 DomTreeNode *Node = DT.getNode(BB);
515 while ((Node = Node->getIDom())) {
516 auto *Defs = MSSA.getBlockDefs(Node->getBlock());
517 if (Defs)
518 return &*Defs->rbegin();
519 }
520 return Result;
521 }
522
523 /// Result of calling walkToPhiOrClobber.
524 struct UpwardsWalkResult {
525 /// The "Result" of the walk. Either a clobber, the last thing we walked, or
526 /// both. Include alias info when clobber found.
527 MemoryAccess *Result;
528 bool IsKnownClobber;
529 Optional<AliasResult> AR;
530 };
531
532 /// Walk to the next Phi or Clobber in the def chain starting at Desc.Last.
533 /// This will update Desc.Last as it walks. It will (optionally) also stop at
534 /// StopAt.
535 ///
536 /// This does not test for whether StopAt is a clobber
537 UpwardsWalkResult
538 walkToPhiOrClobber(DefPath &Desc,
539 const MemoryAccess *StopAt = nullptr) const {
540 assert(!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world")((!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world"
) ? static_cast<void> (0) : __assert_fail ("!isa<MemoryUse>(Desc.Last) && \"Uses don't exist in my world\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 540, __PRETTY_FUNCTION__))
;
541
542 for (MemoryAccess *Current : def_chain(Desc.Last)) {
543 Desc.Last = Current;
544 if (Current == StopAt)
545 return {Current, false, MayAlias};
546
547 if (auto *MD = dyn_cast<MemoryDef>(Current)) {
548 if (MSSA.isLiveOnEntryDef(MD))
549 return {MD, true, MustAlias};
550 ClobberAlias CA =
551 instructionClobbersQuery(MD, Desc.Loc, Query->Inst, AA);
552 if (CA.IsClobber)
553 return {MD, true, CA.AR};
554 }
555 }
556
557 assert(isa<MemoryPhi>(Desc.Last) &&((isa<MemoryPhi>(Desc.Last) && "Ended at a non-clobber that's not a phi?"
) ? static_cast<void> (0) : __assert_fail ("isa<MemoryPhi>(Desc.Last) && \"Ended at a non-clobber that's not a phi?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 558, __PRETTY_FUNCTION__))
558 "Ended at a non-clobber that's not a phi?")((isa<MemoryPhi>(Desc.Last) && "Ended at a non-clobber that's not a phi?"
) ? static_cast<void> (0) : __assert_fail ("isa<MemoryPhi>(Desc.Last) && \"Ended at a non-clobber that's not a phi?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 558, __PRETTY_FUNCTION__))
;
559 return {Desc.Last, false, MayAlias};
560 }
561
562 void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches,
563 ListIndex PriorNode) {
564 auto UpwardDefs = make_range(upward_defs_begin({Phi, Paths[PriorNode].Loc}),
565 upward_defs_end());
566 for (const MemoryAccessPair &P : UpwardDefs) {
567 PausedSearches.push_back(Paths.size());
568 Paths.emplace_back(P.second, P.first, PriorNode);
569 }
570 }
571
572 /// Represents a search that terminated after finding a clobber. This clobber
573 /// may or may not be present in the path of defs from LastNode..SearchStart,
574 /// since it may have been retrieved from cache.
575 struct TerminatedPath {
576 MemoryAccess *Clobber;
577 ListIndex LastNode;
578 };
579
580 /// Get an access that keeps us from optimizing to the given phi.
581 ///
582 /// PausedSearches is an array of indices into the Paths array. Its incoming
583 /// value is the indices of searches that stopped at the last phi optimization
584 /// target. It's left in an unspecified state.
585 ///
586 /// If this returns None, NewPaused is a vector of searches that terminated
587 /// at StopWhere. Otherwise, NewPaused is left in an unspecified state.
588 Optional<TerminatedPath>
589 getBlockingAccess(const MemoryAccess *StopWhere,
590 SmallVectorImpl<ListIndex> &PausedSearches,
591 SmallVectorImpl<ListIndex> &NewPaused,
592 SmallVectorImpl<TerminatedPath> &Terminated) {
593 assert(!PausedSearches.empty() && "No searches to continue?")((!PausedSearches.empty() && "No searches to continue?"
) ? static_cast<void> (0) : __assert_fail ("!PausedSearches.empty() && \"No searches to continue?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 593, __PRETTY_FUNCTION__))
;
594
595 // BFS vs DFS really doesn't make a difference here, so just do a DFS with
596 // PausedSearches as our stack.
597 while (!PausedSearches.empty()) {
598 ListIndex PathIndex = PausedSearches.pop_back_val();
599 DefPath &Node = Paths[PathIndex];
600
601 // If we've already visited this path with this MemoryLocation, we don't
602 // need to do so again.
603 //
604 // NOTE: That we just drop these paths on the ground makes caching
605 // behavior sporadic. e.g. given a diamond:
606 // A
607 // B C
608 // D
609 //
610 // ...If we walk D, B, A, C, we'll only cache the result of phi
611 // optimization for A, B, and D; C will be skipped because it dies here.
612 // This arguably isn't the worst thing ever, since:
613 // - We generally query things in a top-down order, so if we got below D
614 // without needing cache entries for {C, MemLoc}, then chances are
615 // that those cache entries would end up ultimately unused.
616 // - We still cache things for A, so C only needs to walk up a bit.
617 // If this behavior becomes problematic, we can fix without a ton of extra
618 // work.
619 if (!VisitedPhis.insert({Node.Last, Node.Loc}).second)
620 continue;
621
622 UpwardsWalkResult Res = walkToPhiOrClobber(Node, /*StopAt=*/StopWhere);
623 if (Res.IsKnownClobber) {
624 assert(Res.Result != StopWhere)((Res.Result != StopWhere) ? static_cast<void> (0) : __assert_fail
("Res.Result != StopWhere", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 624, __PRETTY_FUNCTION__))
;
625 // If this wasn't a cache hit, we hit a clobber when walking. That's a
626 // failure.
627 TerminatedPath Term{Res.Result, PathIndex};
628 if (!MSSA.dominates(Res.Result, StopWhere))
629 return Term;
630
631 // Otherwise, it's a valid thing to potentially optimize to.
632 Terminated.push_back(Term);
633 continue;
634 }
635
636 if (Res.Result == StopWhere) {
637 // We've hit our target. Save this path off for if we want to continue
638 // walking.
639 NewPaused.push_back(PathIndex);
640 continue;
641 }
642
643 assert(!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber")((!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(Res.Result) && \"liveOnEntry is a clobber\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 643, __PRETTY_FUNCTION__))
;
644 addSearches(cast<MemoryPhi>(Res.Result), PausedSearches, PathIndex);
645 }
646
647 return None;
648 }
649
650 template <typename T, typename Walker>
651 struct generic_def_path_iterator
652 : public iterator_facade_base<generic_def_path_iterator<T, Walker>,
653 std::forward_iterator_tag, T *> {
654 generic_def_path_iterator() = default;
655 generic_def_path_iterator(Walker *W, ListIndex N) : W(W), N(N) {}
656
657 T &operator*() const { return curNode(); }
658
659 generic_def_path_iterator &operator++() {
660 N = curNode().Previous;
661 return *this;
662 }
663
664 bool operator==(const generic_def_path_iterator &O) const {
665 if (N.hasValue() != O.N.hasValue())
666 return false;
667 return !N.hasValue() || *N == *O.N;
668 }
669
670 private:
671 T &curNode() const { return W->Paths[*N]; }
672
673 Walker *W = nullptr;
674 Optional<ListIndex> N = None;
675 };
676
677 using def_path_iterator = generic_def_path_iterator<DefPath, ClobberWalker>;
678 using const_def_path_iterator =
679 generic_def_path_iterator<const DefPath, const ClobberWalker>;
680
681 iterator_range<def_path_iterator> def_path(ListIndex From) {
682 return make_range(def_path_iterator(this, From), def_path_iterator());
683 }
684
685 iterator_range<const_def_path_iterator> const_def_path(ListIndex From) const {
686 return make_range(const_def_path_iterator(this, From),
687 const_def_path_iterator());
688 }
689
690 struct OptznResult {
691 /// The path that contains our result.
692 TerminatedPath PrimaryClobber;
693 /// The paths that we can legally cache back from, but that aren't
694 /// necessarily the result of the Phi optimization.
695 SmallVector<TerminatedPath, 4> OtherClobbers;
696 };
697
698 ListIndex defPathIndex(const DefPath &N) const {
699 // The assert looks nicer if we don't need to do &N
700 const DefPath *NP = &N;
701 assert(!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() &&((!Paths.empty() && NP >= &Paths.front() &&
NP <= &Paths.back() && "Out of bounds DefPath!"
) ? static_cast<void> (0) : __assert_fail ("!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() && \"Out of bounds DefPath!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 702, __PRETTY_FUNCTION__))
702 "Out of bounds DefPath!")((!Paths.empty() && NP >= &Paths.front() &&
NP <= &Paths.back() && "Out of bounds DefPath!"
) ? static_cast<void> (0) : __assert_fail ("!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() && \"Out of bounds DefPath!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 702, __PRETTY_FUNCTION__))
;
703 return NP - &Paths.front();
704 }
705
706 /// Try to optimize a phi as best as we can. Returns a SmallVector of Paths
707 /// that act as legal clobbers. Note that this won't return *all* clobbers.
708 ///
709 /// Phi optimization algorithm tl;dr:
710 /// - Find the earliest def/phi, A, we can optimize to
711 /// - Find if all paths from the starting memory access ultimately reach A
712 /// - If not, optimization isn't possible.
713 /// - Otherwise, walk from A to another clobber or phi, A'.
714 /// - If A' is a def, we're done.
715 /// - If A' is a phi, try to optimize it.
716 ///
717 /// A path is a series of {MemoryAccess, MemoryLocation} pairs. A path
718 /// terminates when a MemoryAccess that clobbers said MemoryLocation is found.
719 OptznResult tryOptimizePhi(MemoryPhi *Phi, MemoryAccess *Start,
720 const MemoryLocation &Loc) {
721 assert(Paths.empty() && VisitedPhis.empty() &&((Paths.empty() && VisitedPhis.empty() && "Reset the optimization state."
) ? static_cast<void> (0) : __assert_fail ("Paths.empty() && VisitedPhis.empty() && \"Reset the optimization state.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 722, __PRETTY_FUNCTION__))
722 "Reset the optimization state.")((Paths.empty() && VisitedPhis.empty() && "Reset the optimization state."
) ? static_cast<void> (0) : __assert_fail ("Paths.empty() && VisitedPhis.empty() && \"Reset the optimization state.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 722, __PRETTY_FUNCTION__))
;
723
724 Paths.emplace_back(Loc, Start, Phi, None);
725 // Stores how many "valid" optimization nodes we had prior to calling
726 // addSearches/getBlockingAccess. Necessary for caching if we had a blocker.
727 auto PriorPathsSize = Paths.size();
728
729 SmallVector<ListIndex, 16> PausedSearches;
730 SmallVector<ListIndex, 8> NewPaused;
731 SmallVector<TerminatedPath, 4> TerminatedPaths;
732
733 addSearches(Phi, PausedSearches, 0);
734
735 // Moves the TerminatedPath with the "most dominated" Clobber to the end of
736 // Paths.
737 auto MoveDominatedPathToEnd = [&](SmallVectorImpl<TerminatedPath> &Paths) {
738 assert(!Paths.empty() && "Need a path to move")((!Paths.empty() && "Need a path to move") ? static_cast
<void> (0) : __assert_fail ("!Paths.empty() && \"Need a path to move\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 738, __PRETTY_FUNCTION__))
;
739 auto Dom = Paths.begin();
740 for (auto I = std::next(Dom), E = Paths.end(); I != E; ++I)
741 if (!MSSA.dominates(I->Clobber, Dom->Clobber))
742 Dom = I;
743 auto Last = Paths.end() - 1;
744 if (Last != Dom)
745 std::iter_swap(Last, Dom);
746 };
747
748 MemoryPhi *Current = Phi;
749 while (true) {
11
Loop condition is true. Entering loop body
750 assert(!MSSA.isLiveOnEntryDef(Current) &&((!MSSA.isLiveOnEntryDef(Current) && "liveOnEntry wasn't treated as a clobber?"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(Current) && \"liveOnEntry wasn't treated as a clobber?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 751, __PRETTY_FUNCTION__))
751 "liveOnEntry wasn't treated as a clobber?")((!MSSA.isLiveOnEntryDef(Current) && "liveOnEntry wasn't treated as a clobber?"
) ? static_cast<void> (0) : __assert_fail ("!MSSA.isLiveOnEntryDef(Current) && \"liveOnEntry wasn't treated as a clobber?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 751, __PRETTY_FUNCTION__))
;
752
753 const auto *Target = getWalkTarget(Current);
754 // If a TerminatedPath doesn't dominate Target, then it wasn't a legal
755 // optimization for the prior phi.
756 assert(all_of(TerminatedPaths, [&](const TerminatedPath &P) {((all_of(TerminatedPaths, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, Target); })) ? static_cast
<void> (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 758, __PRETTY_FUNCTION__))
757 return MSSA.dominates(P.Clobber, Target);((all_of(TerminatedPaths, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, Target); })) ? static_cast
<void> (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 758, __PRETTY_FUNCTION__))
758 }))((all_of(TerminatedPaths, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, Target); })) ? static_cast
<void> (0) : __assert_fail ("all_of(TerminatedPaths, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, Target); })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 758, __PRETTY_FUNCTION__))
;
759
760 // FIXME: This is broken, because the Blocker may be reported to be
761 // liveOnEntry, and we'll happily wait for that to disappear (read: never)
762 // For the moment, this is fine, since we do nothing with blocker info.
763 if (Optional<TerminatedPath> Blocker = getBlockingAccess(
12
Taking false branch
764 Target, PausedSearches, NewPaused, TerminatedPaths)) {
765
766 // Find the node we started at. We can't search based on N->Last, since
767 // we may have gone around a loop with a different MemoryLocation.
768 auto Iter = find_if(def_path(Blocker->LastNode), [&](const DefPath &N) {
769 return defPathIndex(N) < PriorPathsSize;
770 });
771 assert(Iter != def_path_iterator())((Iter != def_path_iterator()) ? static_cast<void> (0) :
__assert_fail ("Iter != def_path_iterator()", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 771, __PRETTY_FUNCTION__))
;
772
773 DefPath &CurNode = *Iter;
774 assert(CurNode.Last == Current)((CurNode.Last == Current) ? static_cast<void> (0) : __assert_fail
("CurNode.Last == Current", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 774, __PRETTY_FUNCTION__))
;
775
776 // Two things:
777 // A. We can't reliably cache all of NewPaused back. Consider a case
778 // where we have two paths in NewPaused; one of which can't optimize
779 // above this phi, whereas the other can. If we cache the second path
780 // back, we'll end up with suboptimal cache entries. We can handle
781 // cases like this a bit better when we either try to find all
782 // clobbers that block phi optimization, or when our cache starts
783 // supporting unfinished searches.
784 // B. We can't reliably cache TerminatedPaths back here without doing
785 // extra checks; consider a case like:
786 // T
787 // / \
788 // D C
789 // \ /
790 // S
791 // Where T is our target, C is a node with a clobber on it, D is a
792 // diamond (with a clobber *only* on the left or right node, N), and
793 // S is our start. Say we walk to D, through the node opposite N
794 // (read: ignoring the clobber), and see a cache entry in the top
795 // node of D. That cache entry gets put into TerminatedPaths. We then
796 // walk up to C (N is later in our worklist), find the clobber, and
797 // quit. If we append TerminatedPaths to OtherClobbers, we'll cache
798 // the bottom part of D to the cached clobber, ignoring the clobber
799 // in N. Again, this problem goes away if we start tracking all
800 // blockers for a given phi optimization.
801 TerminatedPath Result{CurNode.Last, defPathIndex(CurNode)};
802 return {Result, {}};
803 }
804
805 // If there's nothing left to search, then all paths led to valid clobbers
806 // that we got from our cache; pick the nearest to the start, and allow
807 // the rest to be cached back.
808 if (NewPaused.empty()) {
13
Taking false branch
809 MoveDominatedPathToEnd(TerminatedPaths);
810 TerminatedPath Result = TerminatedPaths.pop_back_val();
811 return {Result, std::move(TerminatedPaths)};
812 }
813
814 MemoryAccess *DefChainEnd = nullptr;
14
'DefChainEnd' initialized to a null pointer value
815 SmallVector<TerminatedPath, 4> Clobbers;
816 for (ListIndex Paused : NewPaused) {
15
Assuming '__begin3' is equal to '__end3'
817 UpwardsWalkResult WR = walkToPhiOrClobber(Paths[Paused]);
818 if (WR.IsKnownClobber)
819 Clobbers.push_back({WR.Result, Paused});
820 else
821 // Micro-opt: If we hit the end of the chain, save it.
822 DefChainEnd = WR.Result;
823 }
824
825 if (!TerminatedPaths.empty()) {
16
Taking true branch
826 // If we couldn't find the dominating phi/liveOnEntry in the above loop,
827 // do it now.
828 if (!DefChainEnd)
17
Taking true branch
829 for (auto *MA : def_chain(const_cast<MemoryAccess *>(Target)))
830 DefChainEnd = MA;
831
832 // If any of the terminated paths don't dominate the phi we'll try to
833 // optimize, we need to figure out what they are and quit.
834 const BasicBlock *ChainBB = DefChainEnd->getBlock();
18
Called C++ object pointer is null
835 for (const TerminatedPath &TP : TerminatedPaths) {
836 // Because we know that DefChainEnd is as "high" as we can go, we
837 // don't need local dominance checks; BB dominance is sufficient.
838 if (DT.dominates(ChainBB, TP.Clobber->getBlock()))
839 Clobbers.push_back(TP);
840 }
841 }
842
843 // If we have clobbers in the def chain, find the one closest to Current
844 // and quit.
845 if (!Clobbers.empty()) {
846 MoveDominatedPathToEnd(Clobbers);
847 TerminatedPath Result = Clobbers.pop_back_val();
848 return {Result, std::move(Clobbers)};
849 }
850
851 assert(all_of(NewPaused,((all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last
== DefChainEnd; })) ? static_cast<void> (0) : __assert_fail
("all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last == DefChainEnd; })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 852, __PRETTY_FUNCTION__))
852 [&](ListIndex I) { return Paths[I].Last == DefChainEnd; }))((all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last
== DefChainEnd; })) ? static_cast<void> (0) : __assert_fail
("all_of(NewPaused, [&](ListIndex I) { return Paths[I].Last == DefChainEnd; })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 852, __PRETTY_FUNCTION__))
;
853
854 // Because liveOnEntry is a clobber, this must be a phi.
855 auto *DefChainPhi = cast<MemoryPhi>(DefChainEnd);
856
857 PriorPathsSize = Paths.size();
858 PausedSearches.clear();
859 for (ListIndex I : NewPaused)
860 addSearches(DefChainPhi, PausedSearches, I);
861 NewPaused.clear();
862
863 Current = DefChainPhi;
864 }
865 }
866
867 void verifyOptResult(const OptznResult &R) const {
868 assert(all_of(R.OtherClobbers, [&](const TerminatedPath &P) {((all_of(R.OtherClobbers, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber
); })) ? static_cast<void> (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 870, __PRETTY_FUNCTION__))
869 return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber);((all_of(R.OtherClobbers, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber
); })) ? static_cast<void> (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 870, __PRETTY_FUNCTION__))
870 }))((all_of(R.OtherClobbers, [&](const TerminatedPath &P
) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber
); })) ? static_cast<void> (0) : __assert_fail ("all_of(R.OtherClobbers, [&](const TerminatedPath &P) { return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber); })"
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 870, __PRETTY_FUNCTION__))
;
871 }
872
873 void resetPhiOptznState() {
874 Paths.clear();
875 VisitedPhis.clear();
876 }
877
878public:
879 ClobberWalker(const MemorySSA &MSSA, AliasAnalysis &AA, DominatorTree &DT)
880 : MSSA(MSSA), AA(AA), DT(DT) {}
881
882 /// Finds the nearest clobber for the given query, optimizing phis if
883 /// possible.
884 MemoryAccess *findClobber(MemoryAccess *Start, UpwardsMemoryQuery &Q) {
885 Query = &Q;
886
887 MemoryAccess *Current = Start;
888 // This walker pretends uses don't exist. If we're handed one, silently grab
889 // its def. (This has the nice side-effect of ensuring we never cache uses)
890 if (auto *MU = dyn_cast<MemoryUse>(Start))
8
Taking false branch
891 Current = MU->getDefiningAccess();
892
893 DefPath FirstDesc(Q.StartingLoc, Current, Current, None);
894 // Fast path for the overly-common case (no crazy phi optimization
895 // necessary)
896 UpwardsWalkResult WalkResult = walkToPhiOrClobber(FirstDesc);
897 MemoryAccess *Result;
898 if (WalkResult.IsKnownClobber) {
9
Taking false branch
899 Result = WalkResult.Result;
900 Q.AR = WalkResult.AR;
901 } else {
902 OptznResult OptRes = tryOptimizePhi(cast<MemoryPhi>(FirstDesc.Last),
10
Calling 'ClobberWalker::tryOptimizePhi'
903 Current, Q.StartingLoc);
904 verifyOptResult(OptRes);
905 resetPhiOptznState();
906 Result = OptRes.PrimaryClobber.Clobber;
907 }
908
909#ifdef EXPENSIVE_CHECKS
910 checkClobberSanity(Current, Result, Q.StartingLoc, MSSA, Q, AA);
911#endif
912 return Result;
913 }
914
915 void verify(const MemorySSA *MSSA) { assert(MSSA == &this->MSSA)((MSSA == &this->MSSA) ? static_cast<void> (0) :
__assert_fail ("MSSA == &this->MSSA", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 915, __PRETTY_FUNCTION__))
; }
916};
917
918struct RenamePassData {
919 DomTreeNode *DTN;
920 DomTreeNode::const_iterator ChildIt;
921 MemoryAccess *IncomingVal;
922
923 RenamePassData(DomTreeNode *D, DomTreeNode::const_iterator It,
924 MemoryAccess *M)
925 : DTN(D), ChildIt(It), IncomingVal(M) {}
926
927 void swap(RenamePassData &RHS) {
928 std::swap(DTN, RHS.DTN);
929 std::swap(ChildIt, RHS.ChildIt);
930 std::swap(IncomingVal, RHS.IncomingVal);
931 }
932};
933
934} // end anonymous namespace
935
936namespace llvm {
937
938/// A MemorySSAWalker that does AA walks to disambiguate accesses. It no
939/// longer does caching on its own, but the name has been retained for the
940/// moment.
941class MemorySSA::CachingWalker final : public MemorySSAWalker {
942 ClobberWalker Walker;
943
944 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *, UpwardsMemoryQuery &);
945
946public:
947 CachingWalker(MemorySSA *, AliasAnalysis *, DominatorTree *);
948 ~CachingWalker() override = default;
949
950 using MemorySSAWalker::getClobberingMemoryAccess;
951
952 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *) override;
953 MemoryAccess *getClobberingMemoryAccess(MemoryAccess *,
954 const MemoryLocation &) override;
955 void invalidateInfo(MemoryAccess *) override;
956
957 void verify(const MemorySSA *MSSA) override {
958 MemorySSAWalker::verify(MSSA);
959 Walker.verify(MSSA);
960 }
961};
962
963} // end namespace llvm
964
965void MemorySSA::renameSuccessorPhis(BasicBlock *BB, MemoryAccess *IncomingVal,
966 bool RenameAllUses) {
967 // Pass through values to our successors
968 for (const BasicBlock *S : successors(BB)) {
969 auto It = PerBlockAccesses.find(S);
970 // Rename the phi nodes in our successor block
971 if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
972 continue;
973 AccessList *Accesses = It->second.get();
974 auto *Phi = cast<MemoryPhi>(&Accesses->front());
975 if (RenameAllUses) {
976 int PhiIndex = Phi->getBasicBlockIndex(BB);
977 assert(PhiIndex != -1 && "Incomplete phi during partial rename")((PhiIndex != -1 && "Incomplete phi during partial rename"
) ? static_cast<void> (0) : __assert_fail ("PhiIndex != -1 && \"Incomplete phi during partial rename\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 977, __PRETTY_FUNCTION__))
;
978 Phi->setIncomingValue(PhiIndex, IncomingVal);
979 } else
980 Phi->addIncoming(IncomingVal, BB);
981 }
982}
983
984/// Rename a single basic block into MemorySSA form.
985/// Uses the standard SSA renaming algorithm.
986/// \returns The new incoming value.
987MemoryAccess *MemorySSA::renameBlock(BasicBlock *BB, MemoryAccess *IncomingVal,
988 bool RenameAllUses) {
989 auto It = PerBlockAccesses.find(BB);
990 // Skip most processing if the list is empty.
991 if (It != PerBlockAccesses.end()) {
992 AccessList *Accesses = It->second.get();
993 for (MemoryAccess &L : *Accesses) {
994 if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&L)) {
995 if (MUD->getDefiningAccess() == nullptr || RenameAllUses)
996 MUD->setDefiningAccess(IncomingVal);
997 if (isa<MemoryDef>(&L))
998 IncomingVal = &L;
999 } else {
1000 IncomingVal = &L;
1001 }
1002 }
1003 }
1004 return IncomingVal;
1005}
1006
1007/// This is the standard SSA renaming algorithm.
1008///
1009/// We walk the dominator tree in preorder, renaming accesses, and then filling
1010/// in phi nodes in our successors.
1011void MemorySSA::renamePass(DomTreeNode *Root, MemoryAccess *IncomingVal,
1012 SmallPtrSetImpl<BasicBlock *> &Visited,
1013 bool SkipVisited, bool RenameAllUses) {
1014 SmallVector<RenamePassData, 32> WorkStack;
1015 // Skip everything if we already renamed this block and we are skipping.
1016 // Note: You can't sink this into the if, because we need it to occur
1017 // regardless of whether we skip blocks or not.
1018 bool AlreadyVisited = !Visited.insert(Root->getBlock()).second;
1019 if (SkipVisited && AlreadyVisited)
1020 return;
1021
1022 IncomingVal = renameBlock(Root->getBlock(), IncomingVal, RenameAllUses);
1023 renameSuccessorPhis(Root->getBlock(), IncomingVal, RenameAllUses);
1024 WorkStack.push_back({Root, Root->begin(), IncomingVal});
1025
1026 while (!WorkStack.empty()) {
1027 DomTreeNode *Node = WorkStack.back().DTN;
1028 DomTreeNode::const_iterator ChildIt = WorkStack.back().ChildIt;
1029 IncomingVal = WorkStack.back().IncomingVal;
1030
1031 if (ChildIt == Node->end()) {
1032 WorkStack.pop_back();
1033 } else {
1034 DomTreeNode *Child = *ChildIt;
1035 ++WorkStack.back().ChildIt;
1036 BasicBlock *BB = Child->getBlock();
1037 // Note: You can't sink this into the if, because we need it to occur
1038 // regardless of whether we skip blocks or not.
1039 AlreadyVisited = !Visited.insert(BB).second;
1040 if (SkipVisited && AlreadyVisited) {
1041 // We already visited this during our renaming, which can happen when
1042 // being asked to rename multiple blocks. Figure out the incoming val,
1043 // which is the last def.
1044 // Incoming value can only change if there is a block def, and in that
1045 // case, it's the last block def in the list.
1046 if (auto *BlockDefs = getWritableBlockDefs(BB))
1047 IncomingVal = &*BlockDefs->rbegin();
1048 } else
1049 IncomingVal = renameBlock(BB, IncomingVal, RenameAllUses);
1050 renameSuccessorPhis(BB, IncomingVal, RenameAllUses);
1051 WorkStack.push_back({Child, Child->begin(), IncomingVal});
1052 }
1053 }
1054}
1055
1056/// This handles unreachable block accesses by deleting phi nodes in
1057/// unreachable blocks, and marking all other unreachable MemoryAccess's as
1058/// being uses of the live on entry definition.
1059void MemorySSA::markUnreachableAsLiveOnEntry(BasicBlock *BB) {
1060 assert(!DT->isReachableFromEntry(BB) &&((!DT->isReachableFromEntry(BB) && "Reachable block found while handling unreachable blocks"
) ? static_cast<void> (0) : __assert_fail ("!DT->isReachableFromEntry(BB) && \"Reachable block found while handling unreachable blocks\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1061, __PRETTY_FUNCTION__))
1061 "Reachable block found while handling unreachable blocks")((!DT->isReachableFromEntry(BB) && "Reachable block found while handling unreachable blocks"
) ? static_cast<void> (0) : __assert_fail ("!DT->isReachableFromEntry(BB) && \"Reachable block found while handling unreachable blocks\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1061, __PRETTY_FUNCTION__))
;
1062
1063 // Make sure phi nodes in our reachable successors end up with a
1064 // LiveOnEntryDef for our incoming edge, even though our block is forward
1065 // unreachable. We could just disconnect these blocks from the CFG fully,
1066 // but we do not right now.
1067 for (const BasicBlock *S : successors(BB)) {
1068 if (!DT->isReachableFromEntry(S))
1069 continue;
1070 auto It = PerBlockAccesses.find(S);
1071 // Rename the phi nodes in our successor block
1072 if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1073 continue;
1074 AccessList *Accesses = It->second.get();
1075 auto *Phi = cast<MemoryPhi>(&Accesses->front());
1076 Phi->addIncoming(LiveOnEntryDef.get(), BB);
1077 }
1078
1079 auto It = PerBlockAccesses.find(BB);
1080 if (It == PerBlockAccesses.end())
1081 return;
1082
1083 auto &Accesses = It->second;
1084 for (auto AI = Accesses->begin(), AE = Accesses->end(); AI != AE;) {
1085 auto Next = std::next(AI);
1086 // If we have a phi, just remove it. We are going to replace all
1087 // users with live on entry.
1088 if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(AI))
1089 UseOrDef->setDefiningAccess(LiveOnEntryDef.get());
1090 else
1091 Accesses->erase(AI);
1092 AI = Next;
1093 }
1094}
1095
1096MemorySSA::MemorySSA(Function &Func, AliasAnalysis *AA, DominatorTree *DT)
1097 : AA(AA), DT(DT), F(Func), LiveOnEntryDef(nullptr), Walker(nullptr),
1098 NextID(0) {
1099 buildMemorySSA();
1100}
1101
1102MemorySSA::~MemorySSA() {
1103 // Drop all our references
1104 for (const auto &Pair : PerBlockAccesses)
1105 for (MemoryAccess &MA : *Pair.second)
1106 MA.dropAllReferences();
1107}
1108
1109MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) {
1110 auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr));
1111
1112 if (Res.second)
1113 Res.first->second = llvm::make_unique<AccessList>();
1114 return Res.first->second.get();
1115}
1116
1117MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) {
1118 auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr));
1119
1120 if (Res.second)
1121 Res.first->second = llvm::make_unique<DefsList>();
1122 return Res.first->second.get();
1123}
1124
1125namespace llvm {
1126
1127/// This class is a batch walker of all MemoryUse's in the program, and points
1128/// their defining access at the thing that actually clobbers them. Because it
1129/// is a batch walker that touches everything, it does not operate like the
1130/// other walkers. This walker is basically performing a top-down SSA renaming
1131/// pass, where the version stack is used as the cache. This enables it to be
1132/// significantly more time and memory efficient than using the regular walker,
1133/// which is walking bottom-up.
1134class MemorySSA::OptimizeUses {
1135public:
1136 OptimizeUses(MemorySSA *MSSA, MemorySSAWalker *Walker, AliasAnalysis *AA,
1137 DominatorTree *DT)
1138 : MSSA(MSSA), Walker(Walker), AA(AA), DT(DT) {
1139 Walker = MSSA->getWalker();
1140 }
1141
1142 void optimizeUses();
1143
1144private:
1145 /// This represents where a given memorylocation is in the stack.
1146 struct MemlocStackInfo {
1147 // This essentially is keeping track of versions of the stack. Whenever
1148 // the stack changes due to pushes or pops, these versions increase.
1149 unsigned long StackEpoch;
1150 unsigned long PopEpoch;
1151 // This is the lower bound of places on the stack to check. It is equal to
1152 // the place the last stack walk ended.
1153 // Note: Correctness depends on this being initialized to 0, which densemap
1154 // does
1155 unsigned long LowerBound;
1156 const BasicBlock *LowerBoundBlock;
1157 // This is where the last walk for this memory location ended.
1158 unsigned long LastKill;
1159 bool LastKillValid;
1160 Optional<AliasResult> AR;
1161 };
1162
1163 void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &,
1164 SmallVectorImpl<MemoryAccess *> &,
1165 DenseMap<MemoryLocOrCall, MemlocStackInfo> &);
1166
1167 MemorySSA *MSSA;
1168 MemorySSAWalker *Walker;
1169 AliasAnalysis *AA;
1170 DominatorTree *DT;
1171};
1172
1173} // end namespace llvm
1174
1175/// Optimize the uses in a given block This is basically the SSA renaming
1176/// algorithm, with one caveat: We are able to use a single stack for all
1177/// MemoryUses. This is because the set of *possible* reaching MemoryDefs is
1178/// the same for every MemoryUse. The *actual* clobbering MemoryDef is just
1179/// going to be some position in that stack of possible ones.
1180///
1181/// We track the stack positions that each MemoryLocation needs
1182/// to check, and last ended at. This is because we only want to check the
1183/// things that changed since last time. The same MemoryLocation should
1184/// get clobbered by the same store (getModRefInfo does not use invariantness or
1185/// things like this, and if they start, we can modify MemoryLocOrCall to
1186/// include relevant data)
1187void MemorySSA::OptimizeUses::optimizeUsesInBlock(
1188 const BasicBlock *BB, unsigned long &StackEpoch, unsigned long &PopEpoch,
1189 SmallVectorImpl<MemoryAccess *> &VersionStack,
1190 DenseMap<MemoryLocOrCall, MemlocStackInfo> &LocStackInfo) {
1191
1192 /// If no accesses, nothing to do.
1193 MemorySSA::AccessList *Accesses = MSSA->getWritableBlockAccesses(BB);
1194 if (Accesses == nullptr)
1195 return;
1196
1197 // Pop everything that doesn't dominate the current block off the stack,
1198 // increment the PopEpoch to account for this.
1199 while (true) {
1200 assert(((!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? static_cast<void> (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1202, __PRETTY_FUNCTION__))
1201 !VersionStack.empty() &&((!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? static_cast<void> (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1202, __PRETTY_FUNCTION__))
1202 "Version stack should have liveOnEntry sentinel dominating everything")((!VersionStack.empty() && "Version stack should have liveOnEntry sentinel dominating everything"
) ? static_cast<void> (0) : __assert_fail ("!VersionStack.empty() && \"Version stack should have liveOnEntry sentinel dominating everything\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1202, __PRETTY_FUNCTION__))
;
1203 BasicBlock *BackBlock = VersionStack.back()->getBlock();
1204 if (DT->dominates(BackBlock, BB))
1205 break;
1206 while (VersionStack.back()->getBlock() == BackBlock)
1207 VersionStack.pop_back();
1208 ++PopEpoch;
1209 }
1210
1211 for (MemoryAccess &MA : *Accesses) {
1212 auto *MU = dyn_cast<MemoryUse>(&MA);
1213 if (!MU) {
1214 VersionStack.push_back(&MA);
1215 ++StackEpoch;
1216 continue;
1217 }
1218
1219 if (isUseTriviallyOptimizableToLiveOnEntry(*AA, MU->getMemoryInst())) {
1220 MU->setDefiningAccess(MSSA->getLiveOnEntryDef(), true, None);
1221 continue;
1222 }
1223
1224 MemoryLocOrCall UseMLOC(MU);
1225 auto &LocInfo = LocStackInfo[UseMLOC];
1226 // If the pop epoch changed, it means we've removed stuff from top of
1227 // stack due to changing blocks. We may have to reset the lower bound or
1228 // last kill info.
1229 if (LocInfo.PopEpoch != PopEpoch) {
1230 LocInfo.PopEpoch = PopEpoch;
1231 LocInfo.StackEpoch = StackEpoch;
1232 // If the lower bound was in something that no longer dominates us, we
1233 // have to reset it.
1234 // We can't simply track stack size, because the stack may have had
1235 // pushes/pops in the meantime.
1236 // XXX: This is non-optimal, but only is slower cases with heavily
1237 // branching dominator trees. To get the optimal number of queries would
1238 // be to make lowerbound and lastkill a per-loc stack, and pop it until
1239 // the top of that stack dominates us. This does not seem worth it ATM.
1240 // A much cheaper optimization would be to always explore the deepest
1241 // branch of the dominator tree first. This will guarantee this resets on
1242 // the smallest set of blocks.
1243 if (LocInfo.LowerBoundBlock && LocInfo.LowerBoundBlock != BB &&
1244 !DT->dominates(LocInfo.LowerBoundBlock, BB)) {
1245 // Reset the lower bound of things to check.
1246 // TODO: Some day we should be able to reset to last kill, rather than
1247 // 0.
1248 LocInfo.LowerBound = 0;
1249 LocInfo.LowerBoundBlock = VersionStack[0]->getBlock();
1250 LocInfo.LastKillValid = false;
1251 }
1252 } else if (LocInfo.StackEpoch != StackEpoch) {
1253 // If all that has changed is the StackEpoch, we only have to check the
1254 // new things on the stack, because we've checked everything before. In
1255 // this case, the lower bound of things to check remains the same.
1256 LocInfo.PopEpoch = PopEpoch;
1257 LocInfo.StackEpoch = StackEpoch;
1258 }
1259 if (!LocInfo.LastKillValid) {
1260 LocInfo.LastKill = VersionStack.size() - 1;
1261 LocInfo.LastKillValid = true;
1262 LocInfo.AR = MayAlias;
1263 }
1264
1265 // At this point, we should have corrected last kill and LowerBound to be
1266 // in bounds.
1267 assert(LocInfo.LowerBound < VersionStack.size() &&((LocInfo.LowerBound < VersionStack.size() && "Lower bound out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LowerBound < VersionStack.size() && \"Lower bound out of range\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1268, __PRETTY_FUNCTION__))
1268 "Lower bound out of range")((LocInfo.LowerBound < VersionStack.size() && "Lower bound out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LowerBound < VersionStack.size() && \"Lower bound out of range\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1268, __PRETTY_FUNCTION__))
;
1269 assert(LocInfo.LastKill < VersionStack.size() &&((LocInfo.LastKill < VersionStack.size() && "Last kill info out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LastKill < VersionStack.size() && \"Last kill info out of range\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1270, __PRETTY_FUNCTION__))
1270 "Last kill info out of range")((LocInfo.LastKill < VersionStack.size() && "Last kill info out of range"
) ? static_cast<void> (0) : __assert_fail ("LocInfo.LastKill < VersionStack.size() && \"Last kill info out of range\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1270, __PRETTY_FUNCTION__))
;
1271 // In any case, the new upper bound is the top of the stack.
1272 unsigned long UpperBound = VersionStack.size() - 1;
1273
1274 if (UpperBound - LocInfo.LowerBound > MaxCheckLimit) {
1275 LLVM_DEBUG(dbgs() << "MemorySSA skipping optimization of " << *MU << " ("do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
1276 << *(MU->getMemoryInst()) << ")"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
1277 << " because there are "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
1278 << UpperBound - LocInfo.LowerBounddo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
1279 << " stores to disambiguate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "MemorySSA skipping optimization of "
<< *MU << " (" << *(MU->getMemoryInst()
) << ")" << " because there are " << UpperBound
- LocInfo.LowerBound << " stores to disambiguate\n"; }
} while (false)
;
1280 // Because we did not walk, LastKill is no longer valid, as this may
1281 // have been a kill.
1282 LocInfo.LastKillValid = false;
1283 continue;
1284 }
1285 bool FoundClobberResult = false;
1286 while (UpperBound > LocInfo.LowerBound) {
1287 if (isa<MemoryPhi>(VersionStack[UpperBound])) {
1288 // For phis, use the walker, see where we ended up, go there
1289 Instruction *UseInst = MU->getMemoryInst();
1290 MemoryAccess *Result = Walker->getClobberingMemoryAccess(UseInst);
1291 // We are guaranteed to find it or something is wrong
1292 while (VersionStack[UpperBound] != Result) {
1293 assert(UpperBound != 0)((UpperBound != 0) ? static_cast<void> (0) : __assert_fail
("UpperBound != 0", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1293, __PRETTY_FUNCTION__))
;
1294 --UpperBound;
1295 }
1296 FoundClobberResult = true;
1297 break;
1298 }
1299
1300 MemoryDef *MD = cast<MemoryDef>(VersionStack[UpperBound]);
1301 // If the lifetime of the pointer ends at this instruction, it's live on
1302 // entry.
1303 if (!UseMLOC.IsCall && lifetimeEndsAt(MD, UseMLOC.getLoc(), *AA)) {
1304 // Reset UpperBound to liveOnEntryDef's place in the stack
1305 UpperBound = 0;
1306 FoundClobberResult = true;
1307 LocInfo.AR = MustAlias;
1308 break;
1309 }
1310 ClobberAlias CA = instructionClobbersQuery(MD, MU, UseMLOC, *AA);
1311 if (CA.IsClobber) {
1312 FoundClobberResult = true;
1313 LocInfo.AR = CA.AR;
1314 break;
1315 }
1316 --UpperBound;
1317 }
1318
1319 // Note: Phis always have AliasResult AR set to MayAlias ATM.
1320
1321 // At the end of this loop, UpperBound is either a clobber, or lower bound
1322 // PHI walking may cause it to be < LowerBound, and in fact, < LastKill.
1323 if (FoundClobberResult || UpperBound < LocInfo.LastKill) {
1324 // We were last killed now by where we got to
1325 if (MSSA->isLiveOnEntryDef(VersionStack[UpperBound]))
1326 LocInfo.AR = None;
1327 MU->setDefiningAccess(VersionStack[UpperBound], true, LocInfo.AR);
1328 LocInfo.LastKill = UpperBound;
1329 } else {
1330 // Otherwise, we checked all the new ones, and now we know we can get to
1331 // LastKill.
1332 MU->setDefiningAccess(VersionStack[LocInfo.LastKill], true, LocInfo.AR);
1333 }
1334 LocInfo.LowerBound = VersionStack.size() - 1;
1335 LocInfo.LowerBoundBlock = BB;
1336 }
1337}
1338
1339/// Optimize uses to point to their actual clobbering definitions.
1340void MemorySSA::OptimizeUses::optimizeUses() {
1341 SmallVector<MemoryAccess *, 16> VersionStack;
1342 DenseMap<MemoryLocOrCall, MemlocStackInfo> LocStackInfo;
1343 VersionStack.push_back(MSSA->getLiveOnEntryDef());
1344
1345 unsigned long StackEpoch = 1;
1346 unsigned long PopEpoch = 1;
1347 // We perform a non-recursive top-down dominator tree walk.
1348 for (const auto *DomNode : depth_first(DT->getRootNode()))
1349 optimizeUsesInBlock(DomNode->getBlock(), StackEpoch, PopEpoch, VersionStack,
1350 LocStackInfo);
1351}
1352
1353void MemorySSA::placePHINodes(
1354 const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks) {
1355 // Determine where our MemoryPhi's should go
1356 ForwardIDFCalculator IDFs(*DT);
1357 IDFs.setDefiningBlocks(DefiningBlocks);
1358 SmallVector<BasicBlock *, 32> IDFBlocks;
1359 IDFs.calculate(IDFBlocks);
1360
1361 // Now place MemoryPhi nodes.
1362 for (auto &BB : IDFBlocks)
1363 createMemoryPhi(BB);
1364}
1365
1366void MemorySSA::buildMemorySSA() {
1367 // We create an access to represent "live on entry", for things like
1368 // arguments or users of globals, where the memory they use is defined before
1369 // the beginning of the function. We do not actually insert it into the IR.
1370 // We do not define a live on exit for the immediate uses, and thus our
1371 // semantics do *not* imply that something with no immediate uses can simply
1372 // be removed.
1373 BasicBlock &StartingPoint = F.getEntryBlock();
1374 LiveOnEntryDef.reset(new MemoryDef(F.getContext(), nullptr, nullptr,
1375 &StartingPoint, NextID++));
1376
1377 // We maintain lists of memory accesses per-block, trading memory for time. We
1378 // could just look up the memory access for every possible instruction in the
1379 // stream.
1380 SmallPtrSet<BasicBlock *, 32> DefiningBlocks;
1381 // Go through each block, figure out where defs occur, and chain together all
1382 // the accesses.
1383 for (BasicBlock &B : F) {
1384 bool InsertIntoDef = false;
1385 AccessList *Accesses = nullptr;
1386 DefsList *Defs = nullptr;
1387 for (Instruction &I : B) {
1388 MemoryUseOrDef *MUD = createNewAccess(&I);
1389 if (!MUD)
1390 continue;
1391
1392 if (!Accesses)
1393 Accesses = getOrCreateAccessList(&B);
1394 Accesses->push_back(MUD);
1395 if (isa<MemoryDef>(MUD)) {
1396 InsertIntoDef = true;
1397 if (!Defs)
1398 Defs = getOrCreateDefsList(&B);
1399 Defs->push_back(*MUD);
1400 }
1401 }
1402 if (InsertIntoDef)
1403 DefiningBlocks.insert(&B);
1404 }
1405 placePHINodes(DefiningBlocks);
1406
1407 // Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
1408 // filled in with all blocks.
1409 SmallPtrSet<BasicBlock *, 16> Visited;
1410 renamePass(DT->getRootNode(), LiveOnEntryDef.get(), Visited);
1411
1412 CachingWalker *Walker = getWalkerImpl();
1413
1414 OptimizeUses(this, Walker, AA, DT).optimizeUses();
1415
1416 // Mark the uses in unreachable blocks as live on entry, so that they go
1417 // somewhere.
1418 for (auto &BB : F)
1419 if (!Visited.count(&BB))
1420 markUnreachableAsLiveOnEntry(&BB);
1421}
1422
1423MemorySSAWalker *MemorySSA::getWalker() { return getWalkerImpl(); }
1424
1425MemorySSA::CachingWalker *MemorySSA::getWalkerImpl() {
1426 if (Walker)
1427 return Walker.get();
1428
1429 Walker = llvm::make_unique<CachingWalker>(this, AA, DT);
1430 return Walker.get();
1431}
1432
1433// This is a helper function used by the creation routines. It places NewAccess
1434// into the access and defs lists for a given basic block, at the given
1435// insertion point.
1436void MemorySSA::insertIntoListsForBlock(MemoryAccess *NewAccess,
1437 const BasicBlock *BB,
1438 InsertionPlace Point) {
1439 auto *Accesses = getOrCreateAccessList(BB);
1440 if (Point == Beginning) {
1441 // If it's a phi node, it goes first, otherwise, it goes after any phi
1442 // nodes.
1443 if (isa<MemoryPhi>(NewAccess)) {
1444 Accesses->push_front(NewAccess);
1445 auto *Defs = getOrCreateDefsList(BB);
1446 Defs->push_front(*NewAccess);
1447 } else {
1448 auto AI = find_if_not(
1449 *Accesses, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1450 Accesses->insert(AI, NewAccess);
1451 if (!isa<MemoryUse>(NewAccess)) {
1452 auto *Defs = getOrCreateDefsList(BB);
1453 auto DI = find_if_not(
1454 *Defs, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1455 Defs->insert(DI, *NewAccess);
1456 }
1457 }
1458 } else {
1459 Accesses->push_back(NewAccess);
1460 if (!isa<MemoryUse>(NewAccess)) {
1461 auto *Defs = getOrCreateDefsList(BB);
1462 Defs->push_back(*NewAccess);
1463 }
1464 }
1465 BlockNumberingValid.erase(BB);
1466}
1467
1468void MemorySSA::insertIntoListsBefore(MemoryAccess *What, const BasicBlock *BB,
1469 AccessList::iterator InsertPt) {
1470 auto *Accesses = getWritableBlockAccesses(BB);
1471 bool WasEnd = InsertPt == Accesses->end();
1472 Accesses->insert(AccessList::iterator(InsertPt), What);
1473 if (!isa<MemoryUse>(What)) {
1474 auto *Defs = getOrCreateDefsList(BB);
1475 // If we got asked to insert at the end, we have an easy job, just shove it
1476 // at the end. If we got asked to insert before an existing def, we also get
1477 // an iterator. If we got asked to insert before a use, we have to hunt for
1478 // the next def.
1479 if (WasEnd) {
1480 Defs->push_back(*What);
1481 } else if (isa<MemoryDef>(InsertPt)) {
1482 Defs->insert(InsertPt->getDefsIterator(), *What);
1483 } else {
1484 while (InsertPt != Accesses->end() && !isa<MemoryDef>(InsertPt))
1485 ++InsertPt;
1486 // Either we found a def, or we are inserting at the end
1487 if (InsertPt == Accesses->end())
1488 Defs->push_back(*What);
1489 else
1490 Defs->insert(InsertPt->getDefsIterator(), *What);
1491 }
1492 }
1493 BlockNumberingValid.erase(BB);
1494}
1495
1496void MemorySSA::prepareForMoveTo(MemoryAccess *What, BasicBlock *BB) {
1497 // Keep it in the lookup tables, remove from the lists
1498 removeFromLists(What, false);
1499
1500 // Note that moving should implicitly invalidate the optimized state of a
1501 // MemoryUse (and Phis can't be optimized). However, it doesn't do so for a
1502 // MemoryDef.
1503 if (auto *MD = dyn_cast<MemoryDef>(What))
1504 MD->resetOptimized();
1505 What->setBlock(BB);
1506}
1507
1508// Move What before Where in the IR. The end result is that What will belong to
1509// the right lists and have the right Block set, but will not otherwise be
1510// correct. It will not have the right defining access, and if it is a def,
1511// things below it will not properly be updated.
1512void MemorySSA::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
1513 AccessList::iterator Where) {
1514 prepareForMoveTo(What, BB);
1515 insertIntoListsBefore(What, BB, Where);
1516}
1517
1518void MemorySSA::moveTo(MemoryAccess *What, BasicBlock *BB,
1519 InsertionPlace Point) {
1520 if (isa<MemoryPhi>(What)) {
1521 assert(Point == Beginning &&((Point == Beginning && "Can only move a Phi at the beginning of the block"
) ? static_cast<void> (0) : __assert_fail ("Point == Beginning && \"Can only move a Phi at the beginning of the block\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1522, __PRETTY_FUNCTION__))
1522 "Can only move a Phi at the beginning of the block")((Point == Beginning && "Can only move a Phi at the beginning of the block"
) ? static_cast<void> (0) : __assert_fail ("Point == Beginning && \"Can only move a Phi at the beginning of the block\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1522, __PRETTY_FUNCTION__))
;
1523 // Update lookup table entry
1524 ValueToMemoryAccess.erase(What->getBlock());
1525 bool Inserted = ValueToMemoryAccess.insert({BB, What}).second;
1526 (void)Inserted;
1527 assert(Inserted && "Cannot move a Phi to a block that already has one")((Inserted && "Cannot move a Phi to a block that already has one"
) ? static_cast<void> (0) : __assert_fail ("Inserted && \"Cannot move a Phi to a block that already has one\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1527, __PRETTY_FUNCTION__))
;
1528 }
1529
1530 prepareForMoveTo(What, BB);
1531 insertIntoListsForBlock(What, BB, Point);
1532}
1533
1534MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) {
1535 assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB")((!getMemoryAccess(BB) && "MemoryPhi already exists for this BB"
) ? static_cast<void> (0) : __assert_fail ("!getMemoryAccess(BB) && \"MemoryPhi already exists for this BB\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1535, __PRETTY_FUNCTION__))
;
1536 MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
1537 // Phi's always are placed at the front of the block.
1538 insertIntoListsForBlock(Phi, BB, Beginning);
1539 ValueToMemoryAccess[BB] = Phi;
1540 return Phi;
1541}
1542
1543MemoryUseOrDef *MemorySSA::createDefinedAccess(Instruction *I,
1544 MemoryAccess *Definition,
1545 const MemoryUseOrDef *Template) {
1546 assert(!isa<PHINode>(I) && "Cannot create a defined access for a PHI")((!isa<PHINode>(I) && "Cannot create a defined access for a PHI"
) ? static_cast<void> (0) : __assert_fail ("!isa<PHINode>(I) && \"Cannot create a defined access for a PHI\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1546, __PRETTY_FUNCTION__))
;
1547 MemoryUseOrDef *NewAccess = createNewAccess(I, Template);
1548 assert(((NewAccess != nullptr && "Tried to create a memory access for a non-memory touching instruction"
) ? static_cast<void> (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1550, __PRETTY_FUNCTION__))
1549 NewAccess != nullptr &&((NewAccess != nullptr && "Tried to create a memory access for a non-memory touching instruction"
) ? static_cast<void> (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1550, __PRETTY_FUNCTION__))
1550 "Tried to create a memory access for a non-memory touching instruction")((NewAccess != nullptr && "Tried to create a memory access for a non-memory touching instruction"
) ? static_cast<void> (0) : __assert_fail ("NewAccess != nullptr && \"Tried to create a memory access for a non-memory touching instruction\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1550, __PRETTY_FUNCTION__))
;
1551 NewAccess->setDefiningAccess(Definition);
1552 return NewAccess;
1553}
1554
1555// Return true if the instruction has ordering constraints.
1556// Note specifically that this only considers stores and loads
1557// because others are still considered ModRef by getModRefInfo.
1558static inline bool isOrdered(const Instruction *I) {
1559 if (auto *SI = dyn_cast<StoreInst>(I)) {
1560 if (!SI->isUnordered())
1561 return true;
1562 } else if (auto *LI = dyn_cast<LoadInst>(I)) {
1563 if (!LI->isUnordered())
1564 return true;
1565 }
1566 return false;
1567}
1568
1569/// Helper function to create new memory accesses
1570MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I,
1571 const MemoryUseOrDef *Template) {
1572 // The assume intrinsic has a control dependency which we model by claiming
1573 // that it writes arbitrarily. Ignore that fake memory dependency here.
1574 // FIXME: Replace this special casing with a more accurate modelling of
1575 // assume's control dependency.
1576 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
1577 if (II->getIntrinsicID() == Intrinsic::assume)
1578 return nullptr;
1579
1580 bool Def, Use;
1581 if (Template) {
1582 Def = dyn_cast_or_null<MemoryDef>(Template) != nullptr;
1583 Use = dyn_cast_or_null<MemoryUse>(Template) != nullptr;
1584#if !defined(NDEBUG)
1585 ModRefInfo ModRef = AA->getModRefInfo(I, None);
1586 bool DefCheck, UseCheck;
1587 DefCheck = isModSet(ModRef) || isOrdered(I);
1588 UseCheck = isRefSet(ModRef);
1589 assert(Def == DefCheck && (Def || Use == UseCheck) && "Invalid template")((Def == DefCheck && (Def || Use == UseCheck) &&
"Invalid template") ? static_cast<void> (0) : __assert_fail
("Def == DefCheck && (Def || Use == UseCheck) && \"Invalid template\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1589, __PRETTY_FUNCTION__))
;
1590#endif
1591 } else {
1592 // Find out what affect this instruction has on memory.
1593 ModRefInfo ModRef = AA->getModRefInfo(I, None);
1594 // The isOrdered check is used to ensure that volatiles end up as defs
1595 // (atomics end up as ModRef right now anyway). Until we separate the
1596 // ordering chain from the memory chain, this enables people to see at least
1597 // some relative ordering to volatiles. Note that getClobberingMemoryAccess
1598 // will still give an answer that bypasses other volatile loads. TODO:
1599 // Separate memory aliasing and ordering into two different chains so that
1600 // we can precisely represent both "what memory will this read/write/is
1601 // clobbered by" and "what instructions can I move this past".
1602 Def = isModSet(ModRef) || isOrdered(I);
1603 Use = isRefSet(ModRef);
1604 }
1605
1606 // It's possible for an instruction to not modify memory at all. During
1607 // construction, we ignore them.
1608 if (!Def && !Use)
1609 return nullptr;
1610
1611 MemoryUseOrDef *MUD;
1612 if (Def)
1613 MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++);
1614 else
1615 MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent());
1616 ValueToMemoryAccess[I] = MUD;
1617 return MUD;
1618}
1619
1620/// Returns true if \p Replacer dominates \p Replacee .
1621bool MemorySSA::dominatesUse(const MemoryAccess *Replacer,
1622 const MemoryAccess *Replacee) const {
1623 if (isa<MemoryUseOrDef>(Replacee))
1624 return DT->dominates(Replacer->getBlock(), Replacee->getBlock());
1625 const auto *MP = cast<MemoryPhi>(Replacee);
1626 // For a phi node, the use occurs in the predecessor block of the phi node.
1627 // Since we may occur multiple times in the phi node, we have to check each
1628 // operand to ensure Replacer dominates each operand where Replacee occurs.
1629 for (const Use &Arg : MP->operands()) {
1630 if (Arg.get() != Replacee &&
1631 !DT->dominates(Replacer->getBlock(), MP->getIncomingBlock(Arg)))
1632 return false;
1633 }
1634 return true;
1635}
1636
1637/// Properly remove \p MA from all of MemorySSA's lookup tables.
1638void MemorySSA::removeFromLookups(MemoryAccess *MA) {
1639 assert(MA->use_empty() &&((MA->use_empty() && "Trying to remove memory access that still has uses"
) ? static_cast<void> (0) : __assert_fail ("MA->use_empty() && \"Trying to remove memory access that still has uses\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1640, __PRETTY_FUNCTION__))
1640 "Trying to remove memory access that still has uses")((MA->use_empty() && "Trying to remove memory access that still has uses"
) ? static_cast<void> (0) : __assert_fail ("MA->use_empty() && \"Trying to remove memory access that still has uses\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1640, __PRETTY_FUNCTION__))
;
1641 BlockNumbering.erase(MA);
1642 if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1643 MUD->setDefiningAccess(nullptr);
1644 // Invalidate our walker's cache if necessary
1645 if (!isa<MemoryUse>(MA))
1646 Walker->invalidateInfo(MA);
1647
1648 Value *MemoryInst;
1649 if (const auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1650 MemoryInst = MUD->getMemoryInst();
1651 else
1652 MemoryInst = MA->getBlock();
1653
1654 auto VMA = ValueToMemoryAccess.find(MemoryInst);
1655 if (VMA->second == MA)
1656 ValueToMemoryAccess.erase(VMA);
1657}
1658
1659/// Properly remove \p MA from all of MemorySSA's lists.
1660///
1661/// Because of the way the intrusive list and use lists work, it is important to
1662/// do removal in the right order.
1663/// ShouldDelete defaults to true, and will cause the memory access to also be
1664/// deleted, not just removed.
1665void MemorySSA::removeFromLists(MemoryAccess *MA, bool ShouldDelete) {
1666 BasicBlock *BB = MA->getBlock();
1667 // The access list owns the reference, so we erase it from the non-owning list
1668 // first.
1669 if (!isa<MemoryUse>(MA)) {
1670 auto DefsIt = PerBlockDefs.find(BB);
1671 std::unique_ptr<DefsList> &Defs = DefsIt->second;
1672 Defs->remove(*MA);
1673 if (Defs->empty())
1674 PerBlockDefs.erase(DefsIt);
1675 }
1676
1677 // The erase call here will delete it. If we don't want it deleted, we call
1678 // remove instead.
1679 auto AccessIt = PerBlockAccesses.find(BB);
1680 std::unique_ptr<AccessList> &Accesses = AccessIt->second;
1681 if (ShouldDelete)
1682 Accesses->erase(MA);
1683 else
1684 Accesses->remove(MA);
1685
1686 if (Accesses->empty()) {
1687 PerBlockAccesses.erase(AccessIt);
1688 BlockNumberingValid.erase(BB);
1689 }
1690}
1691
1692void MemorySSA::print(raw_ostream &OS) const {
1693 MemorySSAAnnotatedWriter Writer(this);
1694 F.print(OS, &Writer);
1695}
1696
1697#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1698LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void MemorySSA::dump() const { print(dbgs()); }
1699#endif
1700
1701void MemorySSA::verifyMemorySSA() const {
1702 verifyDefUses(F);
1703 verifyDomination(F);
1704 verifyOrdering(F);
1705 verifyDominationNumbers(F);
1706 Walker->verify(this);
1707 verifyClobberSanity(F);
1708}
1709
1710/// Check sanity of the clobbering instruction for access MA.
1711void MemorySSA::checkClobberSanityAccess(const MemoryAccess *MA) const {
1712 if (const auto *MUD = dyn_cast<MemoryUseOrDef>(MA)) {
1713 if (!MUD->isOptimized())
1714 return;
1715 auto *I = MUD->getMemoryInst();
1716 auto Loc = MemoryLocation::getOrNone(I);
1717 if (Loc == None)
1718 return;
1719 auto *Clobber = MUD->getOptimized();
1720 UpwardsMemoryQuery Q(I, MUD);
1721 checkClobberSanity(MUD, Clobber, *Loc, *this, Q, *AA, true);
1722 }
1723}
1724
1725void MemorySSA::verifyClobberSanity(const Function &F) const {
1726#if !defined(NDEBUG) && defined(EXPENSIVE_CHECKS)
1727 for (const BasicBlock &BB : F) {
1728 const AccessList *Accesses = getBlockAccesses(&BB);
1729 if (!Accesses)
1730 continue;
1731 for (const MemoryAccess &MA : *Accesses)
1732 checkClobberSanityAccess(&MA);
1733 }
1734#endif
1735}
1736
1737/// Verify that all of the blocks we believe to have valid domination numbers
1738/// actually have valid domination numbers.
1739void MemorySSA::verifyDominationNumbers(const Function &F) const {
1740#ifndef NDEBUG
1741 if (BlockNumberingValid.empty())
1742 return;
1743
1744 SmallPtrSet<const BasicBlock *, 16> ValidBlocks = BlockNumberingValid;
1745 for (const BasicBlock &BB : F) {
1746 if (!ValidBlocks.count(&BB))
1747 continue;
1748
1749 ValidBlocks.erase(&BB);
1750
1751 const AccessList *Accesses = getBlockAccesses(&BB);
1752 // It's correct to say an empty block has valid numbering.
1753 if (!Accesses)
1754 continue;
1755
1756 // Block numbering starts at 1.
1757 unsigned long LastNumber = 0;
1758 for (const MemoryAccess &MA : *Accesses) {
1759 auto ThisNumberIter = BlockNumbering.find(&MA);
1760 assert(ThisNumberIter != BlockNumbering.end() &&((ThisNumberIter != BlockNumbering.end() && "MemoryAccess has no domination number in a valid block!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumberIter != BlockNumbering.end() && \"MemoryAccess has no domination number in a valid block!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1761, __PRETTY_FUNCTION__))
1761 "MemoryAccess has no domination number in a valid block!")((ThisNumberIter != BlockNumbering.end() && "MemoryAccess has no domination number in a valid block!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumberIter != BlockNumbering.end() && \"MemoryAccess has no domination number in a valid block!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1761, __PRETTY_FUNCTION__))
;
1762
1763 unsigned long ThisNumber = ThisNumberIter->second;
1764 assert(ThisNumber > LastNumber &&((ThisNumber > LastNumber && "Domination numbers should be strictly increasing!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumber > LastNumber && \"Domination numbers should be strictly increasing!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1765, __PRETTY_FUNCTION__))
1765 "Domination numbers should be strictly increasing!")((ThisNumber > LastNumber && "Domination numbers should be strictly increasing!"
) ? static_cast<void> (0) : __assert_fail ("ThisNumber > LastNumber && \"Domination numbers should be strictly increasing!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1765, __PRETTY_FUNCTION__))
;
1766 LastNumber = ThisNumber;
1767 }
1768 }
1769
1770 assert(ValidBlocks.empty() &&((ValidBlocks.empty() && "All valid BasicBlocks should exist in F -- dangling pointers?"
) ? static_cast<void> (0) : __assert_fail ("ValidBlocks.empty() && \"All valid BasicBlocks should exist in F -- dangling pointers?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1771, __PRETTY_FUNCTION__))
1771 "All valid BasicBlocks should exist in F -- dangling pointers?")((ValidBlocks.empty() && "All valid BasicBlocks should exist in F -- dangling pointers?"
) ? static_cast<void> (0) : __assert_fail ("ValidBlocks.empty() && \"All valid BasicBlocks should exist in F -- dangling pointers?\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1771, __PRETTY_FUNCTION__))
;
1772#endif
1773}
1774
1775/// Verify that the order and existence of MemoryAccesses matches the
1776/// order and existence of memory affecting instructions.
1777void MemorySSA::verifyOrdering(Function &F) const {
1778#ifndef NDEBUG
1779 // Walk all the blocks, comparing what the lookups think and what the access
1780 // lists think, as well as the order in the blocks vs the order in the access
1781 // lists.
1782 SmallVector<MemoryAccess *, 32> ActualAccesses;
1783 SmallVector<MemoryAccess *, 32> ActualDefs;
1784 for (BasicBlock &B : F) {
1785 const AccessList *AL = getBlockAccesses(&B);
1786 const auto *DL = getBlockDefs(&B);
1787 MemoryAccess *Phi = getMemoryAccess(&B);
1788 if (Phi) {
1789 ActualAccesses.push_back(Phi);
1790 ActualDefs.push_back(Phi);
1791 }
1792
1793 for (Instruction &I : B) {
1794 MemoryAccess *MA = getMemoryAccess(&I);
1795 assert((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&(((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&
"We have memory affecting instructions " "in this block but they are not in the "
"access list or defs list") ? static_cast<void> (0) : __assert_fail
("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1798, __PRETTY_FUNCTION__))
1796 "We have memory affecting instructions "(((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&
"We have memory affecting instructions " "in this block but they are not in the "
"access list or defs list") ? static_cast<void> (0) : __assert_fail
("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1798, __PRETTY_FUNCTION__))
1797 "in this block but they are not in the "(((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&
"We have memory affecting instructions " "in this block but they are not in the "
"access list or defs list") ? static_cast<void> (0) : __assert_fail
("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1798, __PRETTY_FUNCTION__))
1798 "access list or defs list")(((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&
"We have memory affecting instructions " "in this block but they are not in the "
"access list or defs list") ? static_cast<void> (0) : __assert_fail
("(!MA || (AL && (isa<MemoryUse>(MA) || DL))) && \"We have memory affecting instructions \" \"in this block but they are not in the \" \"access list or defs list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1798, __PRETTY_FUNCTION__))
;
1799 if (MA) {
1800 ActualAccesses.push_back(MA);
1801 if (isa<MemoryDef>(MA))
1802 ActualDefs.push_back(MA);
1803 }
1804 }
1805 // Either we hit the assert, really have no accesses, or we have both
1806 // accesses and an access list.
1807 // Same with defs.
1808 if (!AL && !DL)
1809 continue;
1810 assert(AL->size() == ActualAccesses.size() &&((AL->size() == ActualAccesses.size() && "We don't have the same number of accesses in the block as on the "
"access list") ? static_cast<void> (0) : __assert_fail
("AL->size() == ActualAccesses.size() && \"We don't have the same number of accesses in the block as on the \" \"access list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1812, __PRETTY_FUNCTION__))
1811 "We don't have the same number of accesses in the block as on the "((AL->size() == ActualAccesses.size() && "We don't have the same number of accesses in the block as on the "
"access list") ? static_cast<void> (0) : __assert_fail
("AL->size() == ActualAccesses.size() && \"We don't have the same number of accesses in the block as on the \" \"access list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1812, __PRETTY_FUNCTION__))
1812 "access list")((AL->size() == ActualAccesses.size() && "We don't have the same number of accesses in the block as on the "
"access list") ? static_cast<void> (0) : __assert_fail
("AL->size() == ActualAccesses.size() && \"We don't have the same number of accesses in the block as on the \" \"access list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1812, __PRETTY_FUNCTION__))
;
1813 assert((DL || ActualDefs.size() == 0) &&(((DL || ActualDefs.size() == 0) && "Either we should have a defs list, or we should have no defs"
) ? static_cast<void> (0) : __assert_fail ("(DL || ActualDefs.size() == 0) && \"Either we should have a defs list, or we should have no defs\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1814, __PRETTY_FUNCTION__))
1814 "Either we should have a defs list, or we should have no defs")(((DL || ActualDefs.size() == 0) && "Either we should have a defs list, or we should have no defs"
) ? static_cast<void> (0) : __assert_fail ("(DL || ActualDefs.size() == 0) && \"Either we should have a defs list, or we should have no defs\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1814, __PRETTY_FUNCTION__))
;
1815 assert((!DL || DL->size() == ActualDefs.size()) &&(((!DL || DL->size() == ActualDefs.size()) && "We don't have the same number of defs in the block as on the "
"def list") ? static_cast<void> (0) : __assert_fail ("(!DL || DL->size() == ActualDefs.size()) && \"We don't have the same number of defs in the block as on the \" \"def list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1817, __PRETTY_FUNCTION__))
1816 "We don't have the same number of defs in the block as on the "(((!DL || DL->size() == ActualDefs.size()) && "We don't have the same number of defs in the block as on the "
"def list") ? static_cast<void> (0) : __assert_fail ("(!DL || DL->size() == ActualDefs.size()) && \"We don't have the same number of defs in the block as on the \" \"def list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1817, __PRETTY_FUNCTION__))
1817 "def list")(((!DL || DL->size() == ActualDefs.size()) && "We don't have the same number of defs in the block as on the "
"def list") ? static_cast<void> (0) : __assert_fail ("(!DL || DL->size() == ActualDefs.size()) && \"We don't have the same number of defs in the block as on the \" \"def list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1817, __PRETTY_FUNCTION__))
;
1818 auto ALI = AL->begin();
1819 auto AAI = ActualAccesses.begin();
1820 while (ALI != AL->end() && AAI != ActualAccesses.end()) {
1821 assert(&*ALI == *AAI && "Not the same accesses in the same order")((&*ALI == *AAI && "Not the same accesses in the same order"
) ? static_cast<void> (0) : __assert_fail ("&*ALI == *AAI && \"Not the same accesses in the same order\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1821, __PRETTY_FUNCTION__))
;
1822 ++ALI;
1823 ++AAI;
1824 }
1825 ActualAccesses.clear();
1826 if (DL) {
1827 auto DLI = DL->begin();
1828 auto ADI = ActualDefs.begin();
1829 while (DLI != DL->end() && ADI != ActualDefs.end()) {
1830 assert(&*DLI == *ADI && "Not the same defs in the same order")((&*DLI == *ADI && "Not the same defs in the same order"
) ? static_cast<void> (0) : __assert_fail ("&*DLI == *ADI && \"Not the same defs in the same order\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1830, __PRETTY_FUNCTION__))
;
1831 ++DLI;
1832 ++ADI;
1833 }
1834 }
1835 ActualDefs.clear();
1836 }
1837#endif
1838}
1839
1840/// Verify the domination properties of MemorySSA by checking that each
1841/// definition dominates all of its uses.
1842void MemorySSA::verifyDomination(Function &F) const {
1843#ifndef NDEBUG
1844 for (BasicBlock &B : F) {
1845 // Phi nodes are attached to basic blocks
1846 if (MemoryPhi *MP = getMemoryAccess(&B))
1847 for (const Use &U : MP->uses())
1848 assert(dominates(MP, U) && "Memory PHI does not dominate it's uses")((dominates(MP, U) && "Memory PHI does not dominate it's uses"
) ? static_cast<void> (0) : __assert_fail ("dominates(MP, U) && \"Memory PHI does not dominate it's uses\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1848, __PRETTY_FUNCTION__))
;
1849
1850 for (Instruction &I : B) {
1851 MemoryAccess *MD = dyn_cast_or_null<MemoryDef>(getMemoryAccess(&I));
1852 if (!MD)
1853 continue;
1854
1855 for (const Use &U : MD->uses())
1856 assert(dominates(MD, U) && "Memory Def does not dominate it's uses")((dominates(MD, U) && "Memory Def does not dominate it's uses"
) ? static_cast<void> (0) : __assert_fail ("dominates(MD, U) && \"Memory Def does not dominate it's uses\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1856, __PRETTY_FUNCTION__))
;
1857 }
1858 }
1859#endif
1860}
1861
1862/// Verify the def-use lists in MemorySSA, by verifying that \p Use
1863/// appears in the use list of \p Def.
1864void MemorySSA::verifyUseInDefs(MemoryAccess *Def, MemoryAccess *Use) const {
1865#ifndef NDEBUG
1866 // The live on entry use may cause us to get a NULL def here
1867 if (!Def)
1868 assert(isLiveOnEntryDef(Use) &&((isLiveOnEntryDef(Use) && "Null def but use not point to live on entry def"
) ? static_cast<void> (0) : __assert_fail ("isLiveOnEntryDef(Use) && \"Null def but use not point to live on entry def\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1869, __PRETTY_FUNCTION__))
1869 "Null def but use not point to live on entry def")((isLiveOnEntryDef(Use) && "Null def but use not point to live on entry def"
) ? static_cast<void> (0) : __assert_fail ("isLiveOnEntryDef(Use) && \"Null def but use not point to live on entry def\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1869, __PRETTY_FUNCTION__))
;
1870 else
1871 assert(is_contained(Def->users(), Use) &&((is_contained(Def->users(), Use) && "Did not find use in def's use list"
) ? static_cast<void> (0) : __assert_fail ("is_contained(Def->users(), Use) && \"Did not find use in def's use list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1872, __PRETTY_FUNCTION__))
1872 "Did not find use in def's use list")((is_contained(Def->users(), Use) && "Did not find use in def's use list"
) ? static_cast<void> (0) : __assert_fail ("is_contained(Def->users(), Use) && \"Did not find use in def's use list\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1872, __PRETTY_FUNCTION__))
;
1873#endif
1874}
1875
1876/// Verify the immediate use information, by walking all the memory
1877/// accesses and verifying that, for each use, it appears in the
1878/// appropriate def's use list
1879void MemorySSA::verifyDefUses(Function &F) const {
1880#ifndef NDEBUG
1881 for (BasicBlock &B : F) {
1882 // Phi nodes are attached to basic blocks
1883 if (MemoryPhi *Phi = getMemoryAccess(&B)) {
1884 assert(Phi->getNumOperands() == static_cast<unsigned>(std::distance(((Phi->getNumOperands() == static_cast<unsigned>(std
::distance( pred_begin(&B), pred_end(&B))) &&
"Incomplete MemoryPhi Node") ? static_cast<void> (0) :
__assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1886, __PRETTY_FUNCTION__))
1885 pred_begin(&B), pred_end(&B))) &&((Phi->getNumOperands() == static_cast<unsigned>(std
::distance( pred_begin(&B), pred_end(&B))) &&
"Incomplete MemoryPhi Node") ? static_cast<void> (0) :
__assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1886, __PRETTY_FUNCTION__))
1886 "Incomplete MemoryPhi Node")((Phi->getNumOperands() == static_cast<unsigned>(std
::distance( pred_begin(&B), pred_end(&B))) &&
"Incomplete MemoryPhi Node") ? static_cast<void> (0) :
__assert_fail ("Phi->getNumOperands() == static_cast<unsigned>(std::distance( pred_begin(&B), pred_end(&B))) && \"Incomplete MemoryPhi Node\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1886, __PRETTY_FUNCTION__))
;
1887 for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
1888 verifyUseInDefs(Phi->getIncomingValue(I), Phi);
1889 assert(find(predecessors(&B), Phi->getIncomingBlock(I)) !=((find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end
(&B) && "Incoming phi block not a block predecessor"
) ? static_cast<void> (0) : __assert_fail ("find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end(&B) && \"Incoming phi block not a block predecessor\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1891, __PRETTY_FUNCTION__))
1890 pred_end(&B) &&((find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end
(&B) && "Incoming phi block not a block predecessor"
) ? static_cast<void> (0) : __assert_fail ("find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end(&B) && \"Incoming phi block not a block predecessor\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1891, __PRETTY_FUNCTION__))
1891 "Incoming phi block not a block predecessor")((find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end
(&B) && "Incoming phi block not a block predecessor"
) ? static_cast<void> (0) : __assert_fail ("find(predecessors(&B), Phi->getIncomingBlock(I)) != pred_end(&B) && \"Incoming phi block not a block predecessor\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1891, __PRETTY_FUNCTION__))
;
1892 }
1893 }
1894
1895 for (Instruction &I : B) {
1896 if (MemoryUseOrDef *MA = getMemoryAccess(&I)) {
1897 verifyUseInDefs(MA->getDefiningAccess(), MA);
1898 }
1899 }
1900 }
1901#endif
1902}
1903
1904/// Perform a local numbering on blocks so that instruction ordering can be
1905/// determined in constant time.
1906/// TODO: We currently just number in order. If we numbered by N, we could
1907/// allow at least N-1 sequences of insertBefore or insertAfter (and at least
1908/// log2(N) sequences of mixed before and after) without needing to invalidate
1909/// the numbering.
1910void MemorySSA::renumberBlock(const BasicBlock *B) const {
1911 // The pre-increment ensures the numbers really start at 1.
1912 unsigned long CurrentNumber = 0;
1913 const AccessList *AL = getBlockAccesses(B);
1914 assert(AL != nullptr && "Asking to renumber an empty block")((AL != nullptr && "Asking to renumber an empty block"
) ? static_cast<void> (0) : __assert_fail ("AL != nullptr && \"Asking to renumber an empty block\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1914, __PRETTY_FUNCTION__))
;
1915 for (const auto &I : *AL)
1916 BlockNumbering[&I] = ++CurrentNumber;
1917 BlockNumberingValid.insert(B);
1918}
1919
1920/// Determine, for two memory accesses in the same block,
1921/// whether \p Dominator dominates \p Dominatee.
1922/// \returns True if \p Dominator dominates \p Dominatee.
1923bool MemorySSA::locallyDominates(const MemoryAccess *Dominator,
1924 const MemoryAccess *Dominatee) const {
1925 const BasicBlock *DominatorBlock = Dominator->getBlock();
1926
1927 assert((DominatorBlock == Dominatee->getBlock()) &&(((DominatorBlock == Dominatee->getBlock()) && "Asking for local domination when accesses are in different blocks!"
) ? static_cast<void> (0) : __assert_fail ("(DominatorBlock == Dominatee->getBlock()) && \"Asking for local domination when accesses are in different blocks!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1928, __PRETTY_FUNCTION__))
1928 "Asking for local domination when accesses are in different blocks!")(((DominatorBlock == Dominatee->getBlock()) && "Asking for local domination when accesses are in different blocks!"
) ? static_cast<void> (0) : __assert_fail ("(DominatorBlock == Dominatee->getBlock()) && \"Asking for local domination when accesses are in different blocks!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1928, __PRETTY_FUNCTION__))
;
1929 // A node dominates itself.
1930 if (Dominatee == Dominator)
1931 return true;
1932
1933 // When Dominatee is defined on function entry, it is not dominated by another
1934 // memory access.
1935 if (isLiveOnEntryDef(Dominatee))
1936 return false;
1937
1938 // When Dominator is defined on function entry, it dominates the other memory
1939 // access.
1940 if (isLiveOnEntryDef(Dominator))
1941 return true;
1942
1943 if (!BlockNumberingValid.count(DominatorBlock))
1944 renumberBlock(DominatorBlock);
1945
1946 unsigned long DominatorNum = BlockNumbering.lookup(Dominator);
1947 // All numbers start with 1
1948 assert(DominatorNum != 0 && "Block was not numbered properly")((DominatorNum != 0 && "Block was not numbered properly"
) ? static_cast<void> (0) : __assert_fail ("DominatorNum != 0 && \"Block was not numbered properly\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1948, __PRETTY_FUNCTION__))
;
1949 unsigned long DominateeNum = BlockNumbering.lookup(Dominatee);
1950 assert(DominateeNum != 0 && "Block was not numbered properly")((DominateeNum != 0 && "Block was not numbered properly"
) ? static_cast<void> (0) : __assert_fail ("DominateeNum != 0 && \"Block was not numbered properly\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1950, __PRETTY_FUNCTION__))
;
1951 return DominatorNum < DominateeNum;
1952}
1953
1954bool MemorySSA::dominates(const MemoryAccess *Dominator,
1955 const MemoryAccess *Dominatee) const {
1956 if (Dominator == Dominatee)
1957 return true;
1958
1959 if (isLiveOnEntryDef(Dominatee))
1960 return false;
1961
1962 if (Dominator->getBlock() != Dominatee->getBlock())
1963 return DT->dominates(Dominator->getBlock(), Dominatee->getBlock());
1964 return locallyDominates(Dominator, Dominatee);
1965}
1966
1967bool MemorySSA::dominates(const MemoryAccess *Dominator,
1968 const Use &Dominatee) const {
1969 if (MemoryPhi *MP = dyn_cast<MemoryPhi>(Dominatee.getUser())) {
1970 BasicBlock *UseBB = MP->getIncomingBlock(Dominatee);
1971 // The def must dominate the incoming block of the phi.
1972 if (UseBB != Dominator->getBlock())
1973 return DT->dominates(Dominator->getBlock(), UseBB);
1974 // If the UseBB and the DefBB are the same, compare locally.
1975 return locallyDominates(Dominator, cast<MemoryAccess>(Dominatee));
1976 }
1977 // If it's not a PHI node use, the normal dominates can already handle it.
1978 return dominates(Dominator, cast<MemoryAccess>(Dominatee.getUser()));
1979}
1980
1981const static char LiveOnEntryStr[] = "liveOnEntry";
1982
1983void MemoryAccess::print(raw_ostream &OS) const {
1984 switch (getValueID()) {
1985 case MemoryPhiVal: return static_cast<const MemoryPhi *>(this)->print(OS);
1986 case MemoryDefVal: return static_cast<const MemoryDef *>(this)->print(OS);
1987 case MemoryUseVal: return static_cast<const MemoryUse *>(this)->print(OS);
1988 }
1989 llvm_unreachable("invalid value id")::llvm::llvm_unreachable_internal("invalid value id", "/build/llvm-toolchain-snapshot-8~svn345461/lib/Analysis/MemorySSA.cpp"
, 1989)
;
1990}
1991
1992void MemoryDef::print(raw_ostream &OS) const {
1993 MemoryAccess *UO = getDefiningAccess();
1994
1995 auto printID = [&OS](MemoryAccess *A) {
1996 if (A && A->getID())
1997 OS << A->getID();
1998 else
1999 OS << LiveOnEntryStr;
2000 };
2001
2002 OS << getID() << " = MemoryDef(";
2003 printID(UO);
2004 OS << ")";
2005
2006 if (isOptimized()) {
2007 OS << "->";
2008 printID(getOptimized());
2009
2010 if (Optional<AliasResult> AR = getOptimizedAccessType())
2011 OS << " " << *AR;
2012 }
2013}
2014
2015void MemoryPhi::print(raw_ostream &OS) const {
2016 bool First = true;
2017 OS << getID() << " = MemoryPhi(";
2018 for (const auto &Op : operands()) {
2019 BasicBlock *BB = getIncomingBlock(Op);
2020 MemoryAccess *MA = cast<MemoryAccess>(Op);
2021 if (!First)
2022 OS << ',';
2023 else
2024 First = false;
2025
2026 OS << '{';
2027 if (BB->hasName())
2028 OS << BB->getName();
2029 else
2030 BB->printAsOperand(OS, false);
2031 OS << ',';
2032 if (unsigned ID = MA->getID())
2033 OS << ID;
2034 else
2035 OS << LiveOnEntryStr;
2036 OS << '}';
2037 }
2038 OS << ')';
2039}
2040
2041void MemoryUse::print(raw_ostream &OS) const {
2042 MemoryAccess *UO = getDefiningAccess();
2043 OS << "MemoryUse(";
2044 if (UO && UO->getID())
2045 OS << UO->getID();
2046 else
2047 OS << LiveOnEntryStr;
2048 OS << ')';
2049
2050 if (Optional<AliasResult> AR = getOptimizedAccessType())
2051 OS << " " << *AR;
2052}
2053
2054void MemoryAccess::dump() const {
2055// Cannot completely remove virtual function even in release mode.
2056#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2057 print(dbgs());
2058 dbgs() << "\n";
2059#endif
2060}
2061
2062char MemorySSAPrinterLegacyPass::ID = 0;
2063
2064MemorySSAPrinterLegacyPass::MemorySSAPrinterLegacyPass() : FunctionPass(ID) {
2065 initializeMemorySSAPrinterLegacyPassPass(*PassRegistry::getPassRegistry());
2066}
2067
2068void MemorySSAPrinterLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
2069 AU.setPreservesAll();
2070 AU.addRequired<MemorySSAWrapperPass>();
2071}
2072
2073bool MemorySSAPrinterLegacyPass::runOnFunction(Function &F) {
2074 auto &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA();
2075 MSSA.print(dbgs());
2076 if (VerifyMemorySSA)
2077 MSSA.verifyMemorySSA();
2078 return false;
2079}
2080
2081AnalysisKey MemorySSAAnalysis::Key;
2082
2083MemorySSAAnalysis::Result MemorySSAAnalysis::run(Function &F,
2084 FunctionAnalysisManager &AM) {
2085 auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
2086 auto &AA = AM.getResult<AAManager>(F);
2087 return MemorySSAAnalysis::Result(llvm::make_unique<MemorySSA>(F, &AA, &DT));
2088}
2089
2090PreservedAnalyses MemorySSAPrinterPass::run(Function &F,
2091 FunctionAnalysisManager &AM) {
2092 OS << "MemorySSA for function: " << F.getName() << "\n";
2093 AM.getResult<MemorySSAAnalysis>(F).getMSSA().print(OS);
2094
2095 return PreservedAnalyses::all();
2096}
2097
2098PreservedAnalyses MemorySSAVerifierPass::run(Function &F,
2099 FunctionAnalysisManager &AM) {
2100 AM.getResult<MemorySSAAnalysis>(F).getMSSA().verifyMemorySSA();
2101
2102 return PreservedAnalyses::all();
2103}
2104
2105char MemorySSAWrapperPass::ID = 0;
2106
2107MemorySSAWrapperPass::MemorySSAWrapperPass() : FunctionPass(ID) {
2108 initializeMemorySSAWrapperPassPass(*PassRegistry::getPassRegistry());
2109}
2110
2111void MemorySSAWrapperPass::releaseMemory() { MSSA.reset(); }
2112
2113void MemorySSAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
2114 AU.setPreservesAll();
2115 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
2116 AU.addRequiredTransitive<AAResultsWrapperPass>();
2117}
2118
2119bool MemorySSAWrapperPass::runOnFunction(Function &F) {
2120 auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2121 auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
2122 MSSA.reset(new MemorySSA(F, &AA, &DT));
2123 return false;
2124}
2125
2126void MemorySSAWrapperPass::verifyAnalysis() const { MSSA->verifyMemorySSA(); }
2127
2128void MemorySSAWrapperPass::print(raw_ostream &OS, const Module *M) const {
2129 MSSA->print(OS);
2130}
2131
2132MemorySSAWalker::MemorySSAWalker(MemorySSA *M) : MSSA(M) {}
2133
2134MemorySSA::CachingWalker::CachingWalker(MemorySSA *M, AliasAnalysis *A,
2135 DominatorTree *D)
2136 : MemorySSAWalker(M), Walker(*M, *A, *D) {}
2137
2138void MemorySSA::CachingWalker::invalidateInfo(MemoryAccess *MA) {
2139 if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
2140 MUD->resetOptimized();
2141}
2142
2143/// Walk the use-def chains starting at \p MA and find
2144/// the MemoryAccess that actually clobbers Loc.
2145///
2146/// \returns our clobbering memory access
2147MemoryAccess *MemorySSA::CachingWalker::getClobberingMemoryAccess(
2148 MemoryAccess *StartingAccess, UpwardsMemoryQuery &Q) {
2149 return Walker.findClobber(StartingAccess, Q);
7
Calling 'ClobberWalker::findClobber'
2150}
2151
2152MemoryAccess *MemorySSA::CachingWalker::getClobberingMemoryAccess(
2153 MemoryAccess *StartingAccess, const MemoryLocation &Loc) {
2154 if (isa<MemoryPhi>(StartingAccess))
2155 return StartingAccess;
2156
2157 auto *StartingUseOrDef = cast<MemoryUseOrDef>(StartingAccess);
2158 if (MSSA->isLiveOnEntryDef(StartingUseOrDef))
2159 return StartingUseOrDef;
2160
2161 Instruction *I = StartingUseOrDef->getMemoryInst();
2162
2163 // Conservatively, fences are always clobbers, so don't perform the walk if we
2164 // hit a fence.
2165 if (!ImmutableCallSite(I) && I->isFenceLike())
2166 return StartingUseOrDef;
2167
2168 UpwardsMemoryQuery Q;
2169 Q.OriginalAccess = StartingUseOrDef;
2170 Q.StartingLoc = Loc;
2171 Q.Inst = I;
2172 Q.IsCall = false;
2173
2174 // Unlike the other function, do not walk to the def of a def, because we are
2175 // handed something we already believe is the clobbering access.
2176 MemoryAccess *DefiningAccess = isa<MemoryUse>(StartingUseOrDef)
2177 ? StartingUseOrDef->getDefiningAccess()
2178 : StartingUseOrDef;
2179
2180 MemoryAccess *Clobber = getClobberingMemoryAccess(DefiningAccess, Q);
2181 LLVM_DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Starting Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2182 LLVM_DEBUG(dbgs() << *StartingUseOrDef << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *StartingUseOrDef << "\n"
; } } while (false)
;
2183 LLVM_DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Final Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2184 LLVM_DEBUG(dbgs() << *Clobber << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *Clobber << "\n"; } } while
(false)
;
2185 return Clobber;
2186}
2187
2188MemoryAccess *
2189MemorySSA::CachingWalker::getClobberingMemoryAccess(MemoryAccess *MA) {
2190 auto *StartingAccess = dyn_cast<MemoryUseOrDef>(MA);
2191 // If this is a MemoryPhi, we can't do anything.
2192 if (!StartingAccess)
1
Taking false branch
2193 return MA;
2194
2195 // If this is an already optimized use or def, return the optimized result.
2196 // Note: Currently, we store the optimized def result in a separate field,
2197 // since we can't use the defining access.
2198 if (StartingAccess->isOptimized())
2
Assuming the condition is false
3
Taking false branch
2199 return StartingAccess->getOptimized();
2200
2201 const Instruction *I = StartingAccess->getMemoryInst();
2202 UpwardsMemoryQuery Q(I, StartingAccess);
2203 // We can't sanely do anything with a fence, since they conservatively clobber
2204 // all memory, and have no locations to get pointers from to try to
2205 // disambiguate.
2206 if (!Q.IsCall && I->isFenceLike())
2207 return StartingAccess;
2208
2209 if (isUseTriviallyOptimizableToLiveOnEntry(*MSSA->AA, I)) {
4
Taking false branch
2210 MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
2211 StartingAccess->setOptimized(LiveOnEntry);
2212 StartingAccess->setOptimizedAccessType(None);
2213 return LiveOnEntry;
2214 }
2215
2216 // Start with the thing we already think clobbers this location
2217 MemoryAccess *DefiningAccess = StartingAccess->getDefiningAccess();
2218
2219 // At this point, DefiningAccess may be the live on entry def.
2220 // If it is, we will not get a better result.
2221 if (MSSA->isLiveOnEntryDef(DefiningAccess)) {
5
Taking false branch
2222 StartingAccess->setOptimized(DefiningAccess);
2223 StartingAccess->setOptimizedAccessType(None);
2224 return DefiningAccess;
2225 }
2226
2227 MemoryAccess *Result = getClobberingMemoryAccess(DefiningAccess, Q);
6
Calling 'CachingWalker::getClobberingMemoryAccess'
2228 LLVM_DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Starting Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2229 LLVM_DEBUG(dbgs() << *DefiningAccess << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *DefiningAccess << "\n"
; } } while (false)
;
2230 LLVM_DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is ")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << "Final Memory SSA clobber for "
<< *I << " is "; } } while (false)
;
2231 LLVM_DEBUG(dbgs() << *Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("memoryssa")) { dbgs() << *Result << "\n"; } } while
(false)
;
2232
2233 StartingAccess->setOptimized(Result);
2234 if (MSSA->isLiveOnEntryDef(Result))
2235 StartingAccess->setOptimizedAccessType(None);
2236 else if (Q.AR == MustAlias)
2237 StartingAccess->setOptimizedAccessType(MustAlias);
2238
2239 return Result;
2240}
2241
2242MemoryAccess *
2243DoNothingMemorySSAWalker::getClobberingMemoryAccess(MemoryAccess *MA) {
2244 if (auto *Use = dyn_cast<MemoryUseOrDef>(MA))
2245 return Use->getDefiningAccess();
2246 return MA;
2247}
2248
2249MemoryAccess *DoNothingMemorySSAWalker::getClobberingMemoryAccess(
2250 MemoryAccess *StartingAccess, const MemoryLocation &) {
2251 if (auto *Use = dyn_cast<MemoryUseOrDef>(StartingAccess))
2252 return Use->getDefiningAccess();
2253 return StartingAccess;
2254}
2255
2256void MemoryPhi::deleteMe(DerivedUser *Self) {
2257 delete static_cast<MemoryPhi *>(Self);
2258}
2259
2260void MemoryDef::deleteMe(DerivedUser *Self) {
2261 delete static_cast<MemoryDef *>(Self);
2262}
2263
2264void MemoryUse::deleteMe(DerivedUser *Self) {
2265 delete static_cast<MemoryUse *>(Self);
2266}