LLVM  9.0.0svn
MemorySSA.cpp
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1 //===- MemorySSA.cpp - Memory SSA Builder ---------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the MemorySSA class.
10 //
11 //===----------------------------------------------------------------------===//
12 
14 #include "llvm/ADT/DenseMap.h"
15 #include "llvm/ADT/DenseMapInfo.h"
16 #include "llvm/ADT/DenseSet.h"
18 #include "llvm/ADT/Hashing.h"
19 #include "llvm/ADT/None.h"
20 #include "llvm/ADT/Optional.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/SmallPtrSet.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/iterator.h"
29 #include "llvm/Config/llvm-config.h"
31 #include "llvm/IR/BasicBlock.h"
32 #include "llvm/IR/Dominators.h"
33 #include "llvm/IR/Function.h"
34 #include "llvm/IR/Instruction.h"
35 #include "llvm/IR/Instructions.h"
36 #include "llvm/IR/IntrinsicInst.h"
37 #include "llvm/IR/Intrinsics.h"
38 #include "llvm/IR/LLVMContext.h"
39 #include "llvm/IR/PassManager.h"
40 #include "llvm/IR/Use.h"
41 #include "llvm/Pass.h"
43 #include "llvm/Support/Casting.h"
45 #include "llvm/Support/Compiler.h"
46 #include "llvm/Support/Debug.h"
50 #include <algorithm>
51 #include <cassert>
52 #include <iterator>
53 #include <memory>
54 #include <utility>
55 
56 using namespace llvm;
57 
58 #define DEBUG_TYPE "memoryssa"
59 
60 INITIALIZE_PASS_BEGIN(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false,
61  true)
65  true)
66 
68  "Memory SSA Printer", false, false)
69 INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
70 INITIALIZE_PASS_END(MemorySSAPrinterLegacyPass, "print-memoryssa",
71  "Memory SSA Printer", false, false)
72 
73 static cl::opt<unsigned> MaxCheckLimit(
74  "memssa-check-limit", cl::Hidden, cl::init(100),
75  cl::desc("The maximum number of stores/phis MemorySSA"
76  "will consider trying to walk past (default = 100)"));
77 
78 // Always verify MemorySSA if expensive checking is enabled.
79 #ifdef EXPENSIVE_CHECKS
80 bool llvm::VerifyMemorySSA = true;
81 #else
82 bool llvm::VerifyMemorySSA = false;
83 #endif
85  VerifyMemorySSAX("verify-memoryssa", cl::location(VerifyMemorySSA),
86  cl::Hidden, cl::desc("Enable verification of MemorySSA."));
87 
88 namespace llvm {
89 
90 /// An assembly annotator class to print Memory SSA information in
91 /// comments.
93  friend class MemorySSA;
94 
95  const MemorySSA *MSSA;
96 
97 public:
98  MemorySSAAnnotatedWriter(const MemorySSA *M) : MSSA(M) {}
99 
101  formatted_raw_ostream &OS) override {
102  if (MemoryAccess *MA = MSSA->getMemoryAccess(BB))
103  OS << "; " << *MA << "\n";
104  }
105 
107  formatted_raw_ostream &OS) override {
108  if (MemoryAccess *MA = MSSA->getMemoryAccess(I))
109  OS << "; " << *MA << "\n";
110  }
111 };
112 
113 } // end namespace llvm
114 
115 namespace {
116 
117 /// Our current alias analysis API differentiates heavily between calls and
118 /// non-calls, and functions called on one usually assert on the other.
119 /// This class encapsulates the distinction to simplify other code that wants
120 /// "Memory affecting instructions and related data" to use as a key.
121 /// For example, this class is used as a densemap key in the use optimizer.
122 class MemoryLocOrCall {
123 public:
124  bool IsCall = false;
125 
126  MemoryLocOrCall(MemoryUseOrDef *MUD)
127  : MemoryLocOrCall(MUD->getMemoryInst()) {}
128  MemoryLocOrCall(const MemoryUseOrDef *MUD)
129  : MemoryLocOrCall(MUD->getMemoryInst()) {}
130 
131  MemoryLocOrCall(Instruction *Inst) {
132  if (auto *C = dyn_cast<CallBase>(Inst)) {
133  IsCall = true;
134  Call = C;
135  } else {
136  IsCall = false;
137  // There is no such thing as a memorylocation for a fence inst, and it is
138  // unique in that regard.
139  if (!isa<FenceInst>(Inst))
140  Loc = MemoryLocation::get(Inst);
141  }
142  }
143 
144  explicit MemoryLocOrCall(const MemoryLocation &Loc) : Loc(Loc) {}
145 
146  const CallBase *getCall() const {
147  assert(IsCall);
148  return Call;
149  }
150 
151  MemoryLocation getLoc() const {
152  assert(!IsCall);
153  return Loc;
154  }
155 
156  bool operator==(const MemoryLocOrCall &Other) const {
157  if (IsCall != Other.IsCall)
158  return false;
159 
160  if (!IsCall)
161  return Loc == Other.Loc;
162 
163  if (Call->getCalledValue() != Other.Call->getCalledValue())
164  return false;
165 
166  return Call->arg_size() == Other.Call->arg_size() &&
167  std::equal(Call->arg_begin(), Call->arg_end(),
168  Other.Call->arg_begin());
169  }
170 
171 private:
172  union {
173  const CallBase *Call;
174  MemoryLocation Loc;
175  };
176 };
177 
178 } // end anonymous namespace
179 
180 namespace llvm {
181 
182 template <> struct DenseMapInfo<MemoryLocOrCall> {
183  static inline MemoryLocOrCall getEmptyKey() {
184  return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getEmptyKey());
185  }
186 
187  static inline MemoryLocOrCall getTombstoneKey() {
188  return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getTombstoneKey());
189  }
190 
191  static unsigned getHashValue(const MemoryLocOrCall &MLOC) {
192  if (!MLOC.IsCall)
193  return hash_combine(
194  MLOC.IsCall,
196 
197  hash_code hash =
199  MLOC.getCall()->getCalledValue()));
200 
201  for (const Value *Arg : MLOC.getCall()->args())
203  return hash;
204  }
205 
206  static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) {
207  return LHS == RHS;
208  }
209 };
210 
211 } // end namespace llvm
212 
213 /// This does one-way checks to see if Use could theoretically be hoisted above
214 /// MayClobber. This will not check the other way around.
215 ///
216 /// This assumes that, for the purposes of MemorySSA, Use comes directly after
217 /// MayClobber, with no potentially clobbering operations in between them.
218 /// (Where potentially clobbering ops are memory barriers, aliased stores, etc.)
219 static bool areLoadsReorderable(const LoadInst *Use,
220  const LoadInst *MayClobber) {
221  bool VolatileUse = Use->isVolatile();
222  bool VolatileClobber = MayClobber->isVolatile();
223  // Volatile operations may never be reordered with other volatile operations.
224  if (VolatileUse && VolatileClobber)
225  return false;
226  // Otherwise, volatile doesn't matter here. From the language reference:
227  // 'optimizers may change the order of volatile operations relative to
228  // non-volatile operations.'"
229 
230  // If a load is seq_cst, it cannot be moved above other loads. If its ordering
231  // is weaker, it can be moved above other loads. We just need to be sure that
232  // MayClobber isn't an acquire load, because loads can't be moved above
233  // acquire loads.
234  //
235  // Note that this explicitly *does* allow the free reordering of monotonic (or
236  // weaker) loads of the same address.
237  bool SeqCstUse = Use->getOrdering() == AtomicOrdering::SequentiallyConsistent;
238  bool MayClobberIsAcquire = isAtLeastOrStrongerThan(MayClobber->getOrdering(),
240  return !(SeqCstUse || MayClobberIsAcquire);
241 }
242 
243 namespace {
244 
245 struct ClobberAlias {
246  bool IsClobber;
248 };
249 
250 } // end anonymous namespace
251 
252 // Return a pair of {IsClobber (bool), AR (AliasResult)}. It relies on AR being
253 // ignored if IsClobber = false.
254 template <typename AliasAnalysisType>
255 static ClobberAlias
257  const Instruction *UseInst, AliasAnalysisType &AA) {
258  Instruction *DefInst = MD->getMemoryInst();
259  assert(DefInst && "Defining instruction not actually an instruction");
260  const auto *UseCall = dyn_cast<CallBase>(UseInst);
262 
263  if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(DefInst)) {
264  // These intrinsics will show up as affecting memory, but they are just
265  // markers, mostly.
266  //
267  // FIXME: We probably don't actually want MemorySSA to model these at all
268  // (including creating MemoryAccesses for them): we just end up inventing
269  // clobbers where they don't really exist at all. Please see D43269 for
270  // context.
271  switch (II->getIntrinsicID()) {
272  case Intrinsic::lifetime_start:
273  if (UseCall)
274  return {false, NoAlias};
275  AR = AA.alias(MemoryLocation(II->getArgOperand(1)), UseLoc);
276  return {AR != NoAlias, AR};
277  case Intrinsic::lifetime_end:
278  case Intrinsic::invariant_start:
279  case Intrinsic::invariant_end:
280  case Intrinsic::assume:
281  return {false, NoAlias};
282  default:
283  break;
284  }
285  }
286 
287  if (UseCall) {
288  ModRefInfo I = AA.getModRefInfo(DefInst, UseCall);
289  AR = isMustSet(I) ? MustAlias : MayAlias;
290  return {isModOrRefSet(I), AR};
291  }
292 
293  if (auto *DefLoad = dyn_cast<LoadInst>(DefInst))
294  if (auto *UseLoad = dyn_cast<LoadInst>(UseInst))
295  return {!areLoadsReorderable(UseLoad, DefLoad), MayAlias};
296 
297  ModRefInfo I = AA.getModRefInfo(DefInst, UseLoc);
298  AR = isMustSet(I) ? MustAlias : MayAlias;
299  return {isModSet(I), AR};
300 }
301 
302 template <typename AliasAnalysisType>
303 static ClobberAlias instructionClobbersQuery(MemoryDef *MD,
304  const MemoryUseOrDef *MU,
305  const MemoryLocOrCall &UseMLOC,
306  AliasAnalysisType &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)
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.
318  AliasAnalysis &AA) {
319  return instructionClobbersQuery(MD, MU, MemoryLocOrCall(MU), AA).IsClobber;
320 }
321 
322 namespace {
323 
324 struct 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;
335  bool SkipSelfAccess = false;
336 
337  UpwardsMemoryQuery() = default;
338 
339  UpwardsMemoryQuery(const Instruction *Inst, const MemoryAccess *Access)
340  : IsCall(isa<CallBase>(Inst)), Inst(Inst), OriginalAccess(Access) {
341  if (!IsCall)
342  StartingLoc = MemoryLocation::get(Inst);
343  }
344 };
345 
346 } // end anonymous namespace
347 
348 static bool lifetimeEndsAt(MemoryDef *MD, const MemoryLocation &Loc,
349  BatchAAResults &AA) {
350  Instruction *Inst = MD->getMemoryInst();
351  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
352  switch (II->getIntrinsicID()) {
353  case Intrinsic::lifetime_end:
354  return AA.alias(MemoryLocation(II->getArgOperand(1)), Loc) == MustAlias;
355  default:
356  return false;
357  }
358  }
359  return false;
360 }
361 
362 template <typename AliasAnalysisType>
363 static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysisType &AA,
364  const Instruction *I) {
365  // If the memory can't be changed, then loads of the memory can't be
366  // clobbered.
367  return isa<LoadInst>(I) && (I->getMetadata(LLVMContext::MD_invariant_load) ||
368  AA.pointsToConstantMemory(MemoryLocation(
369  cast<LoadInst>(I)->getPointerOperand())));
370 }
371 
372 /// Verifies that `Start` is clobbered by `ClobberAt`, and that nothing
373 /// inbetween `Start` and `ClobberAt` can clobbers `Start`.
374 ///
375 /// This is meant to be as simple and self-contained as possible. Because it
376 /// uses no cache, etc., it can be relatively expensive.
377 ///
378 /// \param Start The MemoryAccess that we want to walk from.
379 /// \param ClobberAt A clobber for Start.
380 /// \param StartLoc The MemoryLocation for Start.
381 /// \param MSSA The MemorySSA instance that Start and ClobberAt belong to.
382 /// \param Query The UpwardsMemoryQuery we used for our search.
383 /// \param AA The AliasAnalysis we used for our search.
384 /// \param AllowImpreciseClobber Always false, unless we do relaxed verify.
385 
386 template <typename AliasAnalysisType>
387 LLVM_ATTRIBUTE_UNUSED static void
389  const MemoryLocation &StartLoc, const MemorySSA &MSSA,
390  const UpwardsMemoryQuery &Query, AliasAnalysisType &AA,
391  bool AllowImpreciseClobber = false) {
392  assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?");
393 
394  if (MSSA.isLiveOnEntryDef(Start)) {
395  assert(MSSA.isLiveOnEntryDef(ClobberAt) &&
396  "liveOnEntry must clobber itself");
397  return;
398  }
399 
400  bool FoundClobber = false;
403  Worklist.emplace_back(Start, StartLoc);
404  // Walk all paths from Start to ClobberAt, while looking for clobbers. If one
405  // is found, complain.
406  while (!Worklist.empty()) {
407  auto MAP = Worklist.pop_back_val();
408  // All we care about is that nothing from Start to ClobberAt clobbers Start.
409  // We learn nothing from revisiting nodes.
410  if (!VisitedPhis.insert(MAP).second)
411  continue;
412 
413  for (const auto *MA : def_chain(MAP.first)) {
414  if (MA == ClobberAt) {
415  if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
416  // instructionClobbersQuery isn't essentially free, so don't use `|=`,
417  // since it won't let us short-circuit.
418  //
419  // Also, note that this can't be hoisted out of the `Worklist` loop,
420  // since MD may only act as a clobber for 1 of N MemoryLocations.
421  FoundClobber = FoundClobber || MSSA.isLiveOnEntryDef(MD);
422  if (!FoundClobber) {
423  ClobberAlias CA =
424  instructionClobbersQuery(MD, MAP.second, Query.Inst, AA);
425  if (CA.IsClobber) {
426  FoundClobber = true;
427  // Not used: CA.AR;
428  }
429  }
430  }
431  break;
432  }
433 
434  // We should never hit liveOnEntry, unless it's the clobber.
435  assert(!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?");
436 
437  if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
438  // If Start is a Def, skip self.
439  if (MD == Start)
440  continue;
441 
442  assert(!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA)
443  .IsClobber &&
444  "Found clobber before reaching ClobberAt!");
445  continue;
446  }
447 
448  if (const auto *MU = dyn_cast<MemoryUse>(MA)) {
449  (void)MU;
450  assert (MU == Start &&
451  "Can only find use in def chain if Start is a use");
452  continue;
453  }
454 
455  assert(isa<MemoryPhi>(MA));
456  Worklist.append(
457  upward_defs_begin({const_cast<MemoryAccess *>(MA), MAP.second}),
458  upward_defs_end());
459  }
460  }
461 
462  // If the verify is done following an optimization, it's possible that
463  // ClobberAt was a conservative clobbering, that we can now infer is not a
464  // true clobbering access. Don't fail the verify if that's the case.
465  // We do have accesses that claim they're optimized, but could be optimized
466  // further. Updating all these can be expensive, so allow it for now (FIXME).
467  if (AllowImpreciseClobber)
468  return;
469 
470  // If ClobberAt is a MemoryPhi, we can assume something above it acted as a
471  // clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point.
472  assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&
473  "ClobberAt never acted as a clobber");
474 }
475 
476 namespace {
477 
478 /// Our algorithm for walking (and trying to optimize) clobbers, all wrapped up
479 /// in one class.
480 template <class AliasAnalysisType> class ClobberWalker {
481  /// Save a few bytes by using unsigned instead of size_t.
482  using ListIndex = unsigned;
483 
484  /// Represents a span of contiguous MemoryDefs, potentially ending in a
485  /// MemoryPhi.
486  struct DefPath {
487  MemoryLocation Loc;
488  // Note that, because we always walk in reverse, Last will always dominate
489  // First. Also note that First and Last are inclusive.
490  MemoryAccess *First;
491  MemoryAccess *Last;
492  Optional<ListIndex> Previous;
493 
494  DefPath(const MemoryLocation &Loc, MemoryAccess *First, MemoryAccess *Last,
495  Optional<ListIndex> Previous)
496  : Loc(Loc), First(First), Last(Last), Previous(Previous) {}
497 
498  DefPath(const MemoryLocation &Loc, MemoryAccess *Init,
499  Optional<ListIndex> Previous)
500  : DefPath(Loc, Init, Init, Previous) {}
501  };
502 
503  const MemorySSA &MSSA;
504  AliasAnalysisType &AA;
505  DominatorTree &DT;
506  UpwardsMemoryQuery *Query;
507  unsigned *UpwardWalkLimit;
508 
509  // Phi optimization bookkeeping
512 
513  /// Find the nearest def or phi that `From` can legally be optimized to.
514  const MemoryAccess *getWalkTarget(const MemoryPhi *From) const {
515  assert(From->getNumOperands() && "Phi with no operands?");
516 
517  BasicBlock *BB = From->getBlock();
518  MemoryAccess *Result = MSSA.getLiveOnEntryDef();
519  DomTreeNode *Node = DT.getNode(BB);
520  while ((Node = Node->getIDom())) {
521  auto *Defs = MSSA.getBlockDefs(Node->getBlock());
522  if (Defs)
523  return &*Defs->rbegin();
524  }
525  return Result;
526  }
527 
528  /// Result of calling walkToPhiOrClobber.
529  struct UpwardsWalkResult {
530  /// The "Result" of the walk. Either a clobber, the last thing we walked, or
531  /// both. Include alias info when clobber found.
532  MemoryAccess *Result;
533  bool IsKnownClobber;
535  };
536 
537  /// Walk to the next Phi or Clobber in the def chain starting at Desc.Last.
538  /// This will update Desc.Last as it walks. It will (optionally) also stop at
539  /// StopAt.
540  ///
541  /// This does not test for whether StopAt is a clobber
542  UpwardsWalkResult
543  walkToPhiOrClobber(DefPath &Desc, const MemoryAccess *StopAt = nullptr,
544  const MemoryAccess *SkipStopAt = nullptr) const {
545  assert(!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world");
546  assert(UpwardWalkLimit && "Need a valid walk limit");
547  bool LimitAlreadyReached = false;
548  // (*UpwardWalkLimit) may be 0 here, due to the loop in tryOptimizePhi. Set
549  // it to 1. This will not do any alias() calls. It either returns in the
550  // first iteration in the loop below, or is set back to 0 if all def chains
551  // are free of MemoryDefs.
552  if (!*UpwardWalkLimit) {
553  *UpwardWalkLimit = 1;
554  LimitAlreadyReached = true;
555  }
556 
557  for (MemoryAccess *Current : def_chain(Desc.Last)) {
558  Desc.Last = Current;
559  if (Current == StopAt || Current == SkipStopAt)
560  return {Current, false, MayAlias};
561 
562  if (auto *MD = dyn_cast<MemoryDef>(Current)) {
563  if (MSSA.isLiveOnEntryDef(MD))
564  return {MD, true, MustAlias};
565 
566  if (!--*UpwardWalkLimit)
567  return {Current, true, MayAlias};
568 
569  ClobberAlias CA =
570  instructionClobbersQuery(MD, Desc.Loc, Query->Inst, AA);
571  if (CA.IsClobber)
572  return {MD, true, CA.AR};
573  }
574  }
575 
576  if (LimitAlreadyReached)
577  *UpwardWalkLimit = 0;
578 
579  assert(isa<MemoryPhi>(Desc.Last) &&
580  "Ended at a non-clobber that's not a phi?");
581  return {Desc.Last, false, MayAlias};
582  }
583 
584  void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches,
585  ListIndex PriorNode) {
586  auto UpwardDefs = make_range(upward_defs_begin({Phi, Paths[PriorNode].Loc}),
587  upward_defs_end());
588  for (const MemoryAccessPair &P : UpwardDefs) {
589  PausedSearches.push_back(Paths.size());
590  Paths.emplace_back(P.second, P.first, PriorNode);
591  }
592  }
593 
594  /// Represents a search that terminated after finding a clobber. This clobber
595  /// may or may not be present in the path of defs from LastNode..SearchStart,
596  /// since it may have been retrieved from cache.
597  struct TerminatedPath {
598  MemoryAccess *Clobber;
599  ListIndex LastNode;
600  };
601 
602  /// Get an access that keeps us from optimizing to the given phi.
603  ///
604  /// PausedSearches is an array of indices into the Paths array. Its incoming
605  /// value is the indices of searches that stopped at the last phi optimization
606  /// target. It's left in an unspecified state.
607  ///
608  /// If this returns None, NewPaused is a vector of searches that terminated
609  /// at StopWhere. Otherwise, NewPaused is left in an unspecified state.
611  getBlockingAccess(const MemoryAccess *StopWhere,
612  SmallVectorImpl<ListIndex> &PausedSearches,
613  SmallVectorImpl<ListIndex> &NewPaused,
614  SmallVectorImpl<TerminatedPath> &Terminated) {
615  assert(!PausedSearches.empty() && "No searches to continue?");
616 
617  // BFS vs DFS really doesn't make a difference here, so just do a DFS with
618  // PausedSearches as our stack.
619  while (!PausedSearches.empty()) {
620  ListIndex PathIndex = PausedSearches.pop_back_val();
621  DefPath &Node = Paths[PathIndex];
622 
623  // If we've already visited this path with this MemoryLocation, we don't
624  // need to do so again.
625  //
626  // NOTE: That we just drop these paths on the ground makes caching
627  // behavior sporadic. e.g. given a diamond:
628  // A
629  // B C
630  // D
631  //
632  // ...If we walk D, B, A, C, we'll only cache the result of phi
633  // optimization for A, B, and D; C will be skipped because it dies here.
634  // This arguably isn't the worst thing ever, since:
635  // - We generally query things in a top-down order, so if we got below D
636  // without needing cache entries for {C, MemLoc}, then chances are
637  // that those cache entries would end up ultimately unused.
638  // - We still cache things for A, so C only needs to walk up a bit.
639  // If this behavior becomes problematic, we can fix without a ton of extra
640  // work.
641  if (!VisitedPhis.insert({Node.Last, Node.Loc}).second)
642  continue;
643 
644  const MemoryAccess *SkipStopWhere = nullptr;
645  if (Query->SkipSelfAccess && Node.Loc == Query->StartingLoc) {
646  assert(isa<MemoryDef>(Query->OriginalAccess));
647  SkipStopWhere = Query->OriginalAccess;
648  }
649 
650  UpwardsWalkResult Res = walkToPhiOrClobber(Node,
651  /*StopAt=*/StopWhere,
652  /*SkipStopAt=*/SkipStopWhere);
653  if (Res.IsKnownClobber) {
654  assert(Res.Result != StopWhere && Res.Result != SkipStopWhere);
655 
656  // If this wasn't a cache hit, we hit a clobber when walking. That's a
657  // failure.
658  TerminatedPath Term{Res.Result, PathIndex};
659  if (!MSSA.dominates(Res.Result, StopWhere))
660  return Term;
661 
662  // Otherwise, it's a valid thing to potentially optimize to.
663  Terminated.push_back(Term);
664  continue;
665  }
666 
667  if (Res.Result == StopWhere || Res.Result == SkipStopWhere) {
668  // We've hit our target. Save this path off for if we want to continue
669  // walking. If we are in the mode of skipping the OriginalAccess, and
670  // we've reached back to the OriginalAccess, do not save path, we've
671  // just looped back to self.
672  if (Res.Result != SkipStopWhere)
673  NewPaused.push_back(PathIndex);
674  continue;
675  }
676 
677  assert(!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber");
678  addSearches(cast<MemoryPhi>(Res.Result), PausedSearches, PathIndex);
679  }
680 
681  return None;
682  }
683 
684  template <typename T, typename Walker>
685  struct generic_def_path_iterator
686  : public iterator_facade_base<generic_def_path_iterator<T, Walker>,
687  std::forward_iterator_tag, T *> {
688  generic_def_path_iterator() {}
689  generic_def_path_iterator(Walker *W, ListIndex N) : W(W), N(N) {}
690 
691  T &operator*() const { return curNode(); }
692 
693  generic_def_path_iterator &operator++() {
694  N = curNode().Previous;
695  return *this;
696  }
697 
698  bool operator==(const generic_def_path_iterator &O) const {
699  if (N.hasValue() != O.N.hasValue())
700  return false;
701  return !N.hasValue() || *N == *O.N;
702  }
703 
704  private:
705  T &curNode() const { return W->Paths[*N]; }
706 
707  Walker *W = nullptr;
709  };
710 
711  using def_path_iterator = generic_def_path_iterator<DefPath, ClobberWalker>;
712  using const_def_path_iterator =
713  generic_def_path_iterator<const DefPath, const ClobberWalker>;
714 
715  iterator_range<def_path_iterator> def_path(ListIndex From) {
716  return make_range(def_path_iterator(this, From), def_path_iterator());
717  }
718 
719  iterator_range<const_def_path_iterator> const_def_path(ListIndex From) const {
720  return make_range(const_def_path_iterator(this, From),
721  const_def_path_iterator());
722  }
723 
724  struct OptznResult {
725  /// The path that contains our result.
726  TerminatedPath PrimaryClobber;
727  /// The paths that we can legally cache back from, but that aren't
728  /// necessarily the result of the Phi optimization.
729  SmallVector<TerminatedPath, 4> OtherClobbers;
730  };
731 
732  ListIndex defPathIndex(const DefPath &N) const {
733  // The assert looks nicer if we don't need to do &N
734  const DefPath *NP = &N;
735  assert(!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() &&
736  "Out of bounds DefPath!");
737  return NP - &Paths.front();
738  }
739 
740  /// Try to optimize a phi as best as we can. Returns a SmallVector of Paths
741  /// that act as legal clobbers. Note that this won't return *all* clobbers.
742  ///
743  /// Phi optimization algorithm tl;dr:
744  /// - Find the earliest def/phi, A, we can optimize to
745  /// - Find if all paths from the starting memory access ultimately reach A
746  /// - If not, optimization isn't possible.
747  /// - Otherwise, walk from A to another clobber or phi, A'.
748  /// - If A' is a def, we're done.
749  /// - If A' is a phi, try to optimize it.
750  ///
751  /// A path is a series of {MemoryAccess, MemoryLocation} pairs. A path
752  /// terminates when a MemoryAccess that clobbers said MemoryLocation is found.
753  OptznResult tryOptimizePhi(MemoryPhi *Phi, MemoryAccess *Start,
754  const MemoryLocation &Loc) {
755  assert(Paths.empty() && VisitedPhis.empty() &&
756  "Reset the optimization state.");
757 
758  Paths.emplace_back(Loc, Start, Phi, None);
759  // Stores how many "valid" optimization nodes we had prior to calling
760  // addSearches/getBlockingAccess. Necessary for caching if we had a blocker.
761  auto PriorPathsSize = Paths.size();
762 
763  SmallVector<ListIndex, 16> PausedSearches;
764  SmallVector<ListIndex, 8> NewPaused;
765  SmallVector<TerminatedPath, 4> TerminatedPaths;
766 
767  addSearches(Phi, PausedSearches, 0);
768 
769  // Moves the TerminatedPath with the "most dominated" Clobber to the end of
770  // Paths.
771  auto MoveDominatedPathToEnd = [&](SmallVectorImpl<TerminatedPath> &Paths) {
772  assert(!Paths.empty() && "Need a path to move");
773  auto Dom = Paths.begin();
774  for (auto I = std::next(Dom), E = Paths.end(); I != E; ++I)
775  if (!MSSA.dominates(I->Clobber, Dom->Clobber))
776  Dom = I;
777  auto Last = Paths.end() - 1;
778  if (Last != Dom)
779  std::iter_swap(Last, Dom);
780  };
781 
782  MemoryPhi *Current = Phi;
783  while (true) {
784  assert(!MSSA.isLiveOnEntryDef(Current) &&
785  "liveOnEntry wasn't treated as a clobber?");
786 
787  const auto *Target = getWalkTarget(Current);
788  // If a TerminatedPath doesn't dominate Target, then it wasn't a legal
789  // optimization for the prior phi.
790  assert(all_of(TerminatedPaths, [&](const TerminatedPath &P) {
791  return MSSA.dominates(P.Clobber, Target);
792  }));
793 
794  // FIXME: This is broken, because the Blocker may be reported to be
795  // liveOnEntry, and we'll happily wait for that to disappear (read: never)
796  // For the moment, this is fine, since we do nothing with blocker info.
797  if (Optional<TerminatedPath> Blocker = getBlockingAccess(
798  Target, PausedSearches, NewPaused, TerminatedPaths)) {
799 
800  // Find the node we started at. We can't search based on N->Last, since
801  // we may have gone around a loop with a different MemoryLocation.
802  auto Iter = find_if(def_path(Blocker->LastNode), [&](const DefPath &N) {
803  return defPathIndex(N) < PriorPathsSize;
804  });
805  assert(Iter != def_path_iterator());
806 
807  DefPath &CurNode = *Iter;
808  assert(CurNode.Last == Current);
809 
810  // Two things:
811  // A. We can't reliably cache all of NewPaused back. Consider a case
812  // where we have two paths in NewPaused; one of which can't optimize
813  // above this phi, whereas the other can. If we cache the second path
814  // back, we'll end up with suboptimal cache entries. We can handle
815  // cases like this a bit better when we either try to find all
816  // clobbers that block phi optimization, or when our cache starts
817  // supporting unfinished searches.
818  // B. We can't reliably cache TerminatedPaths back here without doing
819  // extra checks; consider a case like:
820  // T
821  // / \
822  // D C
823  // \ /
824  // S
825  // Where T is our target, C is a node with a clobber on it, D is a
826  // diamond (with a clobber *only* on the left or right node, N), and
827  // S is our start. Say we walk to D, through the node opposite N
828  // (read: ignoring the clobber), and see a cache entry in the top
829  // node of D. That cache entry gets put into TerminatedPaths. We then
830  // walk up to C (N is later in our worklist), find the clobber, and
831  // quit. If we append TerminatedPaths to OtherClobbers, we'll cache
832  // the bottom part of D to the cached clobber, ignoring the clobber
833  // in N. Again, this problem goes away if we start tracking all
834  // blockers for a given phi optimization.
835  TerminatedPath Result{CurNode.Last, defPathIndex(CurNode)};
836  return {Result, {}};
837  }
838 
839  // If there's nothing left to search, then all paths led to valid clobbers
840  // that we got from our cache; pick the nearest to the start, and allow
841  // the rest to be cached back.
842  if (NewPaused.empty()) {
843  MoveDominatedPathToEnd(TerminatedPaths);
844  TerminatedPath Result = TerminatedPaths.pop_back_val();
845  return {Result, std::move(TerminatedPaths)};
846  }
847 
848  MemoryAccess *DefChainEnd = nullptr;
850  for (ListIndex Paused : NewPaused) {
851  UpwardsWalkResult WR = walkToPhiOrClobber(Paths[Paused]);
852  if (WR.IsKnownClobber)
853  Clobbers.push_back({WR.Result, Paused});
854  else
855  // Micro-opt: If we hit the end of the chain, save it.
856  DefChainEnd = WR.Result;
857  }
858 
859  if (!TerminatedPaths.empty()) {
860  // If we couldn't find the dominating phi/liveOnEntry in the above loop,
861  // do it now.
862  if (!DefChainEnd)
863  for (auto *MA : def_chain(const_cast<MemoryAccess *>(Target)))
864  DefChainEnd = MA;
865 
866  // If any of the terminated paths don't dominate the phi we'll try to
867  // optimize, we need to figure out what they are and quit.
868  const BasicBlock *ChainBB = DefChainEnd->getBlock();
869  for (const TerminatedPath &TP : TerminatedPaths) {
870  // Because we know that DefChainEnd is as "high" as we can go, we
871  // don't need local dominance checks; BB dominance is sufficient.
872  if (DT.dominates(ChainBB, TP.Clobber->getBlock()))
873  Clobbers.push_back(TP);
874  }
875  }
876 
877  // If we have clobbers in the def chain, find the one closest to Current
878  // and quit.
879  if (!Clobbers.empty()) {
880  MoveDominatedPathToEnd(Clobbers);
881  TerminatedPath Result = Clobbers.pop_back_val();
882  return {Result, std::move(Clobbers)};
883  }
884 
885  assert(all_of(NewPaused,
886  [&](ListIndex I) { return Paths[I].Last == DefChainEnd; }));
887 
888  // Because liveOnEntry is a clobber, this must be a phi.
889  auto *DefChainPhi = cast<MemoryPhi>(DefChainEnd);
890 
891  PriorPathsSize = Paths.size();
892  PausedSearches.clear();
893  for (ListIndex I : NewPaused)
894  addSearches(DefChainPhi, PausedSearches, I);
895  NewPaused.clear();
896 
897  Current = DefChainPhi;
898  }
899  }
900 
901  void verifyOptResult(const OptznResult &R) const {
902  assert(all_of(R.OtherClobbers, [&](const TerminatedPath &P) {
903  return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber);
904  }));
905  }
906 
907  void resetPhiOptznState() {
908  Paths.clear();
909  VisitedPhis.clear();
910  }
911 
912 public:
913  ClobberWalker(const MemorySSA &MSSA, AliasAnalysisType &AA, DominatorTree &DT)
914  : MSSA(MSSA), AA(AA), DT(DT) {}
915 
916  AliasAnalysisType *getAA() { return &AA; }
917  /// Finds the nearest clobber for the given query, optimizing phis if
918  /// possible.
919  MemoryAccess *findClobber(MemoryAccess *Start, UpwardsMemoryQuery &Q,
920  unsigned &UpWalkLimit) {
921  Query = &Q;
922  UpwardWalkLimit = &UpWalkLimit;
923  // Starting limit must be > 0.
924  if (!UpWalkLimit)
925  UpWalkLimit++;
926 
927  MemoryAccess *Current = Start;
928  // This walker pretends uses don't exist. If we're handed one, silently grab
929  // its def. (This has the nice side-effect of ensuring we never cache uses)
930  if (auto *MU = dyn_cast<MemoryUse>(Start))
931  Current = MU->getDefiningAccess();
932 
933  DefPath FirstDesc(Q.StartingLoc, Current, Current, None);
934  // Fast path for the overly-common case (no crazy phi optimization
935  // necessary)
936  UpwardsWalkResult WalkResult = walkToPhiOrClobber(FirstDesc);
937  MemoryAccess *Result;
938  if (WalkResult.IsKnownClobber) {
939  Result = WalkResult.Result;
940  Q.AR = WalkResult.AR;
941  } else {
942  OptznResult OptRes = tryOptimizePhi(cast<MemoryPhi>(FirstDesc.Last),
943  Current, Q.StartingLoc);
944  verifyOptResult(OptRes);
945  resetPhiOptznState();
946  Result = OptRes.PrimaryClobber.Clobber;
947  }
948 
949 #ifdef EXPENSIVE_CHECKS
950  if (!Q.SkipSelfAccess && *UpwardWalkLimit > 0)
951  checkClobberSanity(Current, Result, Q.StartingLoc, MSSA, Q, AA);
952 #endif
953  return Result;
954  }
955 };
956 
957 struct RenamePassData {
958  DomTreeNode *DTN;
960  MemoryAccess *IncomingVal;
961 
962  RenamePassData(DomTreeNode *D, DomTreeNode::const_iterator It,
963  MemoryAccess *M)
964  : DTN(D), ChildIt(It), IncomingVal(M) {}
965 
966  void swap(RenamePassData &RHS) {
967  std::swap(DTN, RHS.DTN);
968  std::swap(ChildIt, RHS.ChildIt);
969  std::swap(IncomingVal, RHS.IncomingVal);
970  }
971 };
972 
973 } // end anonymous namespace
974 
975 namespace llvm {
976 
977 template <class AliasAnalysisType> class MemorySSA::ClobberWalkerBase {
978  ClobberWalker<AliasAnalysisType> Walker;
979  MemorySSA *MSSA;
980 
981 public:
982  ClobberWalkerBase(MemorySSA *M, AliasAnalysisType *A, DominatorTree *D)
983  : Walker(*M, *A, *D), MSSA(M) {}
984 
985  MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *,
986  const MemoryLocation &,
987  unsigned &);
988  // Third argument (bool), defines whether the clobber search should skip the
989  // original queried access. If true, there will be a follow-up query searching
990  // for a clobber access past "self". Note that the Optimized access is not
991  // updated if a new clobber is found by this SkipSelf search. If this
992  // additional query becomes heavily used we may decide to cache the result.
993  // Walker instantiations will decide how to set the SkipSelf bool.
994  MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *, unsigned &, bool);
995 };
996 
997 /// A MemorySSAWalker that does AA walks to disambiguate accesses. It no
998 /// longer does caching on its own, but the name has been retained for the
999 /// moment.
1000 template <class AliasAnalysisType>
1001 class MemorySSA::CachingWalker final : public MemorySSAWalker {
1002  ClobberWalkerBase<AliasAnalysisType> *Walker;
1003 
1004 public:
1005  CachingWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
1006  : MemorySSAWalker(M), Walker(W) {}
1007  ~CachingWalker() override = default;
1008 
1010 
1011  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
1012  return Walker->getClobberingMemoryAccessBase(MA, UWL, false);
1013  }
1014  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1015  const MemoryLocation &Loc,
1016  unsigned &UWL) {
1017  return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
1018  }
1019 
1020  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
1021  unsigned UpwardWalkLimit = MaxCheckLimit;
1022  return getClobberingMemoryAccess(MA, UpwardWalkLimit);
1023  }
1024  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1025  const MemoryLocation &Loc) override {
1026  unsigned UpwardWalkLimit = MaxCheckLimit;
1027  return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
1028  }
1029 
1030  void invalidateInfo(MemoryAccess *MA) override {
1031  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1032  MUD->resetOptimized();
1033  }
1034 };
1035 
1036 template <class AliasAnalysisType>
1037 class MemorySSA::SkipSelfWalker final : public MemorySSAWalker {
1038  ClobberWalkerBase<AliasAnalysisType> *Walker;
1039 
1040 public:
1041  SkipSelfWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
1042  : MemorySSAWalker(M), Walker(W) {}
1043  ~SkipSelfWalker() override = default;
1044 
1046 
1047  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
1048  return Walker->getClobberingMemoryAccessBase(MA, UWL, true);
1049  }
1050  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1051  const MemoryLocation &Loc,
1052  unsigned &UWL) {
1053  return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
1054  }
1055 
1056  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
1057  unsigned UpwardWalkLimit = MaxCheckLimit;
1058  return getClobberingMemoryAccess(MA, UpwardWalkLimit);
1059  }
1060  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1061  const MemoryLocation &Loc) override {
1062  unsigned UpwardWalkLimit = MaxCheckLimit;
1063  return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
1064  }
1065 
1066  void invalidateInfo(MemoryAccess *MA) override {
1067  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1068  MUD->resetOptimized();
1069  }
1070 };
1071 
1072 } // end namespace llvm
1073 
1074 void MemorySSA::renameSuccessorPhis(BasicBlock *BB, MemoryAccess *IncomingVal,
1075  bool RenameAllUses) {
1076  // Pass through values to our successors
1077  for (const BasicBlock *S : successors(BB)) {
1078  auto It = PerBlockAccesses.find(S);
1079  // Rename the phi nodes in our successor block
1080  if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1081  continue;
1082  AccessList *Accesses = It->second.get();
1083  auto *Phi = cast<MemoryPhi>(&Accesses->front());
1084  if (RenameAllUses) {
1085  int PhiIndex = Phi->getBasicBlockIndex(BB);
1086  assert(PhiIndex != -1 && "Incomplete phi during partial rename");
1087  Phi->setIncomingValue(PhiIndex, IncomingVal);
1088  } else
1089  Phi->addIncoming(IncomingVal, BB);
1090  }
1091 }
1092 
1093 /// Rename a single basic block into MemorySSA form.
1094 /// Uses the standard SSA renaming algorithm.
1095 /// \returns The new incoming value.
1096 MemoryAccess *MemorySSA::renameBlock(BasicBlock *BB, MemoryAccess *IncomingVal,
1097  bool RenameAllUses) {
1098  auto It = PerBlockAccesses.find(BB);
1099  // Skip most processing if the list is empty.
1100  if (It != PerBlockAccesses.end()) {
1101  AccessList *Accesses = It->second.get();
1102  for (MemoryAccess &L : *Accesses) {
1103  if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&L)) {
1104  if (MUD->getDefiningAccess() == nullptr || RenameAllUses)
1105  MUD->setDefiningAccess(IncomingVal);
1106  if (isa<MemoryDef>(&L))
1107  IncomingVal = &L;
1108  } else {
1109  IncomingVal = &L;
1110  }
1111  }
1112  }
1113  return IncomingVal;
1114 }
1115 
1116 /// This is the standard SSA renaming algorithm.
1117 ///
1118 /// We walk the dominator tree in preorder, renaming accesses, and then filling
1119 /// in phi nodes in our successors.
1120 void MemorySSA::renamePass(DomTreeNode *Root, MemoryAccess *IncomingVal,
1122  bool SkipVisited, bool RenameAllUses) {
1124  // Skip everything if we already renamed this block and we are skipping.
1125  // Note: You can't sink this into the if, because we need it to occur
1126  // regardless of whether we skip blocks or not.
1127  bool AlreadyVisited = !Visited.insert(Root->getBlock()).second;
1128  if (SkipVisited && AlreadyVisited)
1129  return;
1130 
1131  IncomingVal = renameBlock(Root->getBlock(), IncomingVal, RenameAllUses);
1132  renameSuccessorPhis(Root->getBlock(), IncomingVal, RenameAllUses);
1133  WorkStack.push_back({Root, Root->begin(), IncomingVal});
1134 
1135  while (!WorkStack.empty()) {
1136  DomTreeNode *Node = WorkStack.back().DTN;
1137  DomTreeNode::const_iterator ChildIt = WorkStack.back().ChildIt;
1138  IncomingVal = WorkStack.back().IncomingVal;
1139 
1140  if (ChildIt == Node->end()) {
1141  WorkStack.pop_back();
1142  } else {
1143  DomTreeNode *Child = *ChildIt;
1144  ++WorkStack.back().ChildIt;
1145  BasicBlock *BB = Child->getBlock();
1146  // Note: You can't sink this into the if, because we need it to occur
1147  // regardless of whether we skip blocks or not.
1148  AlreadyVisited = !Visited.insert(BB).second;
1149  if (SkipVisited && AlreadyVisited) {
1150  // We already visited this during our renaming, which can happen when
1151  // being asked to rename multiple blocks. Figure out the incoming val,
1152  // which is the last def.
1153  // Incoming value can only change if there is a block def, and in that
1154  // case, it's the last block def in the list.
1155  if (auto *BlockDefs = getWritableBlockDefs(BB))
1156  IncomingVal = &*BlockDefs->rbegin();
1157  } else
1158  IncomingVal = renameBlock(BB, IncomingVal, RenameAllUses);
1159  renameSuccessorPhis(BB, IncomingVal, RenameAllUses);
1160  WorkStack.push_back({Child, Child->begin(), IncomingVal});
1161  }
1162  }
1163 }
1164 
1165 /// This handles unreachable block accesses by deleting phi nodes in
1166 /// unreachable blocks, and marking all other unreachable MemoryAccess's as
1167 /// being uses of the live on entry definition.
1168 void MemorySSA::markUnreachableAsLiveOnEntry(BasicBlock *BB) {
1169  assert(!DT->isReachableFromEntry(BB) &&
1170  "Reachable block found while handling unreachable blocks");
1171 
1172  // Make sure phi nodes in our reachable successors end up with a
1173  // LiveOnEntryDef for our incoming edge, even though our block is forward
1174  // unreachable. We could just disconnect these blocks from the CFG fully,
1175  // but we do not right now.
1176  for (const BasicBlock *S : successors(BB)) {
1177  if (!DT->isReachableFromEntry(S))
1178  continue;
1179  auto It = PerBlockAccesses.find(S);
1180  // Rename the phi nodes in our successor block
1181  if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1182  continue;
1183  AccessList *Accesses = It->second.get();
1184  auto *Phi = cast<MemoryPhi>(&Accesses->front());
1185  Phi->addIncoming(LiveOnEntryDef.get(), BB);
1186  }
1187 
1188  auto It = PerBlockAccesses.find(BB);
1189  if (It == PerBlockAccesses.end())
1190  return;
1191 
1192  auto &Accesses = It->second;
1193  for (auto AI = Accesses->begin(), AE = Accesses->end(); AI != AE;) {
1194  auto Next = std::next(AI);
1195  // If we have a phi, just remove it. We are going to replace all
1196  // users with live on entry.
1197  if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(AI))
1198  UseOrDef->setDefiningAccess(LiveOnEntryDef.get());
1199  else
1200  Accesses->erase(AI);
1201  AI = Next;
1202  }
1203 }
1204 
1206  : AA(nullptr), DT(DT), F(Func), LiveOnEntryDef(nullptr), Walker(nullptr),
1207  SkipWalker(nullptr), NextID(0) {
1208  // Build MemorySSA using a batch alias analysis. This reuses the internal
1209  // state that AA collects during an alias()/getModRefInfo() call. This is
1210  // safe because there are no CFG changes while building MemorySSA and can
1211  // significantly reduce the time spent by the compiler in AA, because we will
1212  // make queries about all the instructions in the Function.
1213  BatchAAResults BatchAA(*AA);
1214  buildMemorySSA(BatchAA);
1215  // Intentionally leave AA to nullptr while building so we don't accidently
1216  // use non-batch AliasAnalysis.
1217  this->AA = AA;
1218  // Also create the walker here.
1219  getWalker();
1220 }
1221 
1223  // Drop all our references
1224  for (const auto &Pair : PerBlockAccesses)
1225  for (MemoryAccess &MA : *Pair.second)
1226  MA.dropAllReferences();
1227 }
1228 
1229 MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) {
1230  auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr));
1231 
1232  if (Res.second)
1233  Res.first->second = llvm::make_unique<AccessList>();
1234  return Res.first->second.get();
1235 }
1236 
1237 MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) {
1238  auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr));
1239 
1240  if (Res.second)
1241  Res.first->second = llvm::make_unique<DefsList>();
1242  return Res.first->second.get();
1243 }
1244 
1245 namespace llvm {
1246 
1247 /// This class is a batch walker of all MemoryUse's in the program, and points
1248 /// their defining access at the thing that actually clobbers them. Because it
1249 /// is a batch walker that touches everything, it does not operate like the
1250 /// other walkers. This walker is basically performing a top-down SSA renaming
1251 /// pass, where the version stack is used as the cache. This enables it to be
1252 /// significantly more time and memory efficient than using the regular walker,
1253 /// which is walking bottom-up.
1255 public:
1256  OptimizeUses(MemorySSA *MSSA, CachingWalker<BatchAAResults> *Walker,
1257  BatchAAResults *BAA, DominatorTree *DT)
1258  : MSSA(MSSA), Walker(Walker), AA(BAA), DT(DT) {}
1259 
1260  void optimizeUses();
1261 
1262 private:
1263  /// This represents where a given memorylocation is in the stack.
1264  struct MemlocStackInfo {
1265  // This essentially is keeping track of versions of the stack. Whenever
1266  // the stack changes due to pushes or pops, these versions increase.
1267  unsigned long StackEpoch;
1268  unsigned long PopEpoch;
1269  // This is the lower bound of places on the stack to check. It is equal to
1270  // the place the last stack walk ended.
1271  // Note: Correctness depends on this being initialized to 0, which densemap
1272  // does
1273  unsigned long LowerBound;
1274  const BasicBlock *LowerBoundBlock;
1275  // This is where the last walk for this memory location ended.
1276  unsigned long LastKill;
1277  bool LastKillValid;
1279  };
1280 
1281  void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &,
1284 
1285  MemorySSA *MSSA;
1286  CachingWalker<BatchAAResults> *Walker;
1287  BatchAAResults *AA;
1288  DominatorTree *DT;
1289 };
1290 
1291 } // end namespace llvm
1292 
1293 /// Optimize the uses in a given block This is basically the SSA renaming
1294 /// algorithm, with one caveat: We are able to use a single stack for all
1295 /// MemoryUses. This is because the set of *possible* reaching MemoryDefs is
1296 /// the same for every MemoryUse. The *actual* clobbering MemoryDef is just
1297 /// going to be some position in that stack of possible ones.
1298 ///
1299 /// We track the stack positions that each MemoryLocation needs
1300 /// to check, and last ended at. This is because we only want to check the
1301 /// things that changed since last time. The same MemoryLocation should
1302 /// get clobbered by the same store (getModRefInfo does not use invariantness or
1303 /// things like this, and if they start, we can modify MemoryLocOrCall to
1304 /// include relevant data)
1305 void MemorySSA::OptimizeUses::optimizeUsesInBlock(
1306  const BasicBlock *BB, unsigned long &StackEpoch, unsigned long &PopEpoch,
1307  SmallVectorImpl<MemoryAccess *> &VersionStack,
1309 
1310  /// If no accesses, nothing to do.
1311  MemorySSA::AccessList *Accesses = MSSA->getWritableBlockAccesses(BB);
1312  if (Accesses == nullptr)
1313  return;
1314 
1315  // Pop everything that doesn't dominate the current block off the stack,
1316  // increment the PopEpoch to account for this.
1317  while (true) {
1318  assert(
1319  !VersionStack.empty() &&
1320  "Version stack should have liveOnEntry sentinel dominating everything");
1321  BasicBlock *BackBlock = VersionStack.back()->getBlock();
1322  if (DT->dominates(BackBlock, BB))
1323  break;
1324  while (VersionStack.back()->getBlock() == BackBlock)
1325  VersionStack.pop_back();
1326  ++PopEpoch;
1327  }
1328 
1329  for (MemoryAccess &MA : *Accesses) {
1330  auto *MU = dyn_cast<MemoryUse>(&MA);
1331  if (!MU) {
1332  VersionStack.push_back(&MA);
1333  ++StackEpoch;
1334  continue;
1335  }
1336 
1337  if (isUseTriviallyOptimizableToLiveOnEntry(*AA, MU->getMemoryInst())) {
1338  MU->setDefiningAccess(MSSA->getLiveOnEntryDef(), true, None);
1339  continue;
1340  }
1341 
1342  MemoryLocOrCall UseMLOC(MU);
1343  auto &LocInfo = LocStackInfo[UseMLOC];
1344  // If the pop epoch changed, it means we've removed stuff from top of
1345  // stack due to changing blocks. We may have to reset the lower bound or
1346  // last kill info.
1347  if (LocInfo.PopEpoch != PopEpoch) {
1348  LocInfo.PopEpoch = PopEpoch;
1349  LocInfo.StackEpoch = StackEpoch;
1350  // If the lower bound was in something that no longer dominates us, we
1351  // have to reset it.
1352  // We can't simply track stack size, because the stack may have had
1353  // pushes/pops in the meantime.
1354  // XXX: This is non-optimal, but only is slower cases with heavily
1355  // branching dominator trees. To get the optimal number of queries would
1356  // be to make lowerbound and lastkill a per-loc stack, and pop it until
1357  // the top of that stack dominates us. This does not seem worth it ATM.
1358  // A much cheaper optimization would be to always explore the deepest
1359  // branch of the dominator tree first. This will guarantee this resets on
1360  // the smallest set of blocks.
1361  if (LocInfo.LowerBoundBlock && LocInfo.LowerBoundBlock != BB &&
1362  !DT->dominates(LocInfo.LowerBoundBlock, BB)) {
1363  // Reset the lower bound of things to check.
1364  // TODO: Some day we should be able to reset to last kill, rather than
1365  // 0.
1366  LocInfo.LowerBound = 0;
1367  LocInfo.LowerBoundBlock = VersionStack[0]->getBlock();
1368  LocInfo.LastKillValid = false;
1369  }
1370  } else if (LocInfo.StackEpoch != StackEpoch) {
1371  // If all that has changed is the StackEpoch, we only have to check the
1372  // new things on the stack, because we've checked everything before. In
1373  // this case, the lower bound of things to check remains the same.
1374  LocInfo.PopEpoch = PopEpoch;
1375  LocInfo.StackEpoch = StackEpoch;
1376  }
1377  if (!LocInfo.LastKillValid) {
1378  LocInfo.LastKill = VersionStack.size() - 1;
1379  LocInfo.LastKillValid = true;
1380  LocInfo.AR = MayAlias;
1381  }
1382 
1383  // At this point, we should have corrected last kill and LowerBound to be
1384  // in bounds.
1385  assert(LocInfo.LowerBound < VersionStack.size() &&
1386  "Lower bound out of range");
1387  assert(LocInfo.LastKill < VersionStack.size() &&
1388  "Last kill info out of range");
1389  // In any case, the new upper bound is the top of the stack.
1390  unsigned long UpperBound = VersionStack.size() - 1;
1391 
1392  if (UpperBound - LocInfo.LowerBound > MaxCheckLimit) {
1393  LLVM_DEBUG(dbgs() << "MemorySSA skipping optimization of " << *MU << " ("
1394  << *(MU->getMemoryInst()) << ")"
1395  << " because there are "
1396  << UpperBound - LocInfo.LowerBound
1397  << " stores to disambiguate\n");
1398  // Because we did not walk, LastKill is no longer valid, as this may
1399  // have been a kill.
1400  LocInfo.LastKillValid = false;
1401  continue;
1402  }
1403  bool FoundClobberResult = false;
1404  unsigned UpwardWalkLimit = MaxCheckLimit;
1405  while (UpperBound > LocInfo.LowerBound) {
1406  if (isa<MemoryPhi>(VersionStack[UpperBound])) {
1407  // For phis, use the walker, see where we ended up, go there
1408  MemoryAccess *Result =
1409  Walker->getClobberingMemoryAccess(MU, UpwardWalkLimit);
1410  // We are guaranteed to find it or something is wrong
1411  while (VersionStack[UpperBound] != Result) {
1412  assert(UpperBound != 0);
1413  --UpperBound;
1414  }
1415  FoundClobberResult = true;
1416  break;
1417  }
1418 
1419  MemoryDef *MD = cast<MemoryDef>(VersionStack[UpperBound]);
1420  // If the lifetime of the pointer ends at this instruction, it's live on
1421  // entry.
1422  if (!UseMLOC.IsCall && lifetimeEndsAt(MD, UseMLOC.getLoc(), *AA)) {
1423  // Reset UpperBound to liveOnEntryDef's place in the stack
1424  UpperBound = 0;
1425  FoundClobberResult = true;
1426  LocInfo.AR = MustAlias;
1427  break;
1428  }
1429  ClobberAlias CA = instructionClobbersQuery(MD, MU, UseMLOC, *AA);
1430  if (CA.IsClobber) {
1431  FoundClobberResult = true;
1432  LocInfo.AR = CA.AR;
1433  break;
1434  }
1435  --UpperBound;
1436  }
1437 
1438  // Note: Phis always have AliasResult AR set to MayAlias ATM.
1439 
1440  // At the end of this loop, UpperBound is either a clobber, or lower bound
1441  // PHI walking may cause it to be < LowerBound, and in fact, < LastKill.
1442  if (FoundClobberResult || UpperBound < LocInfo.LastKill) {
1443  // We were last killed now by where we got to
1444  if (MSSA->isLiveOnEntryDef(VersionStack[UpperBound]))
1445  LocInfo.AR = None;
1446  MU->setDefiningAccess(VersionStack[UpperBound], true, LocInfo.AR);
1447  LocInfo.LastKill = UpperBound;
1448  } else {
1449  // Otherwise, we checked all the new ones, and now we know we can get to
1450  // LastKill.
1451  MU->setDefiningAccess(VersionStack[LocInfo.LastKill], true, LocInfo.AR);
1452  }
1453  LocInfo.LowerBound = VersionStack.size() - 1;
1454  LocInfo.LowerBoundBlock = BB;
1455  }
1456 }
1457 
1458 /// Optimize uses to point to their actual clobbering definitions.
1460  SmallVector<MemoryAccess *, 16> VersionStack;
1462  VersionStack.push_back(MSSA->getLiveOnEntryDef());
1463 
1464  unsigned long StackEpoch = 1;
1465  unsigned long PopEpoch = 1;
1466  // We perform a non-recursive top-down dominator tree walk.
1467  for (const auto *DomNode : depth_first(DT->getRootNode()))
1468  optimizeUsesInBlock(DomNode->getBlock(), StackEpoch, PopEpoch, VersionStack,
1469  LocStackInfo);
1470 }
1471 
1472 void MemorySSA::placePHINodes(
1473  const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks) {
1474  // Determine where our MemoryPhi's should go
1475  ForwardIDFCalculator IDFs(*DT);
1476  IDFs.setDefiningBlocks(DefiningBlocks);
1478  IDFs.calculate(IDFBlocks);
1479 
1480  // Now place MemoryPhi nodes.
1481  for (auto &BB : IDFBlocks)
1482  createMemoryPhi(BB);
1483 }
1484 
1485 void MemorySSA::buildMemorySSA(BatchAAResults &BAA) {
1486  // We create an access to represent "live on entry", for things like
1487  // arguments or users of globals, where the memory they use is defined before
1488  // the beginning of the function. We do not actually insert it into the IR.
1489  // We do not define a live on exit for the immediate uses, and thus our
1490  // semantics do *not* imply that something with no immediate uses can simply
1491  // be removed.
1492  BasicBlock &StartingPoint = F.getEntryBlock();
1493  LiveOnEntryDef.reset(new MemoryDef(F.getContext(), nullptr, nullptr,
1494  &StartingPoint, NextID++));
1495 
1496  // We maintain lists of memory accesses per-block, trading memory for time. We
1497  // could just look up the memory access for every possible instruction in the
1498  // stream.
1499  SmallPtrSet<BasicBlock *, 32> DefiningBlocks;
1500  // Go through each block, figure out where defs occur, and chain together all
1501  // the accesses.
1502  for (BasicBlock &B : F) {
1503  bool InsertIntoDef = false;
1504  AccessList *Accesses = nullptr;
1505  DefsList *Defs = nullptr;
1506  for (Instruction &I : B) {
1507  MemoryUseOrDef *MUD = createNewAccess(&I, &BAA);
1508  if (!MUD)
1509  continue;
1510 
1511  if (!Accesses)
1512  Accesses = getOrCreateAccessList(&B);
1513  Accesses->push_back(MUD);
1514  if (isa<MemoryDef>(MUD)) {
1515  InsertIntoDef = true;
1516  if (!Defs)
1517  Defs = getOrCreateDefsList(&B);
1518  Defs->push_back(*MUD);
1519  }
1520  }
1521  if (InsertIntoDef)
1522  DefiningBlocks.insert(&B);
1523  }
1524  placePHINodes(DefiningBlocks);
1525 
1526  // Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
1527  // filled in with all blocks.
1529  renamePass(DT->getRootNode(), LiveOnEntryDef.get(), Visited);
1530 
1531  ClobberWalkerBase<BatchAAResults> WalkerBase(this, &BAA, DT);
1532  CachingWalker<BatchAAResults> WalkerLocal(this, &WalkerBase);
1533  OptimizeUses(this, &WalkerLocal, &BAA, DT).optimizeUses();
1534 
1535  // Mark the uses in unreachable blocks as live on entry, so that they go
1536  // somewhere.
1537  for (auto &BB : F)
1538  if (!Visited.count(&BB))
1539  markUnreachableAsLiveOnEntry(&BB);
1540 }
1541 
1542 MemorySSAWalker *MemorySSA::getWalker() { return getWalkerImpl(); }
1543 
1544 MemorySSA::CachingWalker<AliasAnalysis> *MemorySSA::getWalkerImpl() {
1545  if (Walker)
1546  return Walker.get();
1547 
1548  if (!WalkerBase)
1549  WalkerBase =
1550  llvm::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);
1551 
1552  Walker =
1553  llvm::make_unique<CachingWalker<AliasAnalysis>>(this, WalkerBase.get());
1554  return Walker.get();
1555 }
1556 
1558  if (SkipWalker)
1559  return SkipWalker.get();
1560 
1561  if (!WalkerBase)
1562  WalkerBase =
1563  llvm::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);
1564 
1565  SkipWalker =
1566  llvm::make_unique<SkipSelfWalker<AliasAnalysis>>(this, WalkerBase.get());
1567  return SkipWalker.get();
1568  }
1569 
1570 
1571 // This is a helper function used by the creation routines. It places NewAccess
1572 // into the access and defs lists for a given basic block, at the given
1573 // insertion point.
1575  const BasicBlock *BB,
1576  InsertionPlace Point) {
1577  auto *Accesses = getOrCreateAccessList(BB);
1578  if (Point == Beginning) {
1579  // If it's a phi node, it goes first, otherwise, it goes after any phi
1580  // nodes.
1581  if (isa<MemoryPhi>(NewAccess)) {
1582  Accesses->push_front(NewAccess);
1583  auto *Defs = getOrCreateDefsList(BB);
1584  Defs->push_front(*NewAccess);
1585  } else {
1586  auto AI = find_if_not(
1587  *Accesses, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1588  Accesses->insert(AI, NewAccess);
1589  if (!isa<MemoryUse>(NewAccess)) {
1590  auto *Defs = getOrCreateDefsList(BB);
1591  auto DI = find_if_not(
1592  *Defs, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1593  Defs->insert(DI, *NewAccess);
1594  }
1595  }
1596  } else {
1597  Accesses->push_back(NewAccess);
1598  if (!isa<MemoryUse>(NewAccess)) {
1599  auto *Defs = getOrCreateDefsList(BB);
1600  Defs->push_back(*NewAccess);
1601  }
1602  }
1603  BlockNumberingValid.erase(BB);
1604 }
1605 
1607  AccessList::iterator InsertPt) {
1608  auto *Accesses = getWritableBlockAccesses(BB);
1609  bool WasEnd = InsertPt == Accesses->end();
1610  Accesses->insert(AccessList::iterator(InsertPt), What);
1611  if (!isa<MemoryUse>(What)) {
1612  auto *Defs = getOrCreateDefsList(BB);
1613  // If we got asked to insert at the end, we have an easy job, just shove it
1614  // at the end. If we got asked to insert before an existing def, we also get
1615  // an iterator. If we got asked to insert before a use, we have to hunt for
1616  // the next def.
1617  if (WasEnd) {
1618  Defs->push_back(*What);
1619  } else if (isa<MemoryDef>(InsertPt)) {
1620  Defs->insert(InsertPt->getDefsIterator(), *What);
1621  } else {
1622  while (InsertPt != Accesses->end() && !isa<MemoryDef>(InsertPt))
1623  ++InsertPt;
1624  // Either we found a def, or we are inserting at the end
1625  if (InsertPt == Accesses->end())
1626  Defs->push_back(*What);
1627  else
1628  Defs->insert(InsertPt->getDefsIterator(), *What);
1629  }
1630  }
1631  BlockNumberingValid.erase(BB);
1632 }
1633 
1634 void MemorySSA::prepareForMoveTo(MemoryAccess *What, BasicBlock *BB) {
1635  // Keep it in the lookup tables, remove from the lists
1636  removeFromLists(What, false);
1637 
1638  // Note that moving should implicitly invalidate the optimized state of a
1639  // MemoryUse (and Phis can't be optimized). However, it doesn't do so for a
1640  // MemoryDef.
1641  if (auto *MD = dyn_cast<MemoryDef>(What))
1642  MD->resetOptimized();
1643  What->setBlock(BB);
1644 }
1645 
1646 // Move What before Where in the IR. The end result is that What will belong to
1647 // the right lists and have the right Block set, but will not otherwise be
1648 // correct. It will not have the right defining access, and if it is a def,
1649 // things below it will not properly be updated.
1651  AccessList::iterator Where) {
1652  prepareForMoveTo(What, BB);
1653  insertIntoListsBefore(What, BB, Where);
1654 }
1655 
1657  InsertionPlace Point) {
1658  if (isa<MemoryPhi>(What)) {
1659  assert(Point == Beginning &&
1660  "Can only move a Phi at the beginning of the block");
1661  // Update lookup table entry
1662  ValueToMemoryAccess.erase(What->getBlock());
1663  bool Inserted = ValueToMemoryAccess.insert({BB, What}).second;
1664  (void)Inserted;
1665  assert(Inserted && "Cannot move a Phi to a block that already has one");
1666  }
1667 
1668  prepareForMoveTo(What, BB);
1669  insertIntoListsForBlock(What, BB, Point);
1670 }
1671 
1672 MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) {
1673  assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB");
1674  MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
1675  // Phi's always are placed at the front of the block.
1677  ValueToMemoryAccess[BB] = Phi;
1678  return Phi;
1679 }
1680 
1682  MemoryAccess *Definition,
1683  const MemoryUseOrDef *Template) {
1684  assert(!isa<PHINode>(I) && "Cannot create a defined access for a PHI");
1685  MemoryUseOrDef *NewAccess = createNewAccess(I, AA, Template);
1686  assert(
1687  NewAccess != nullptr &&
1688  "Tried to create a memory access for a non-memory touching instruction");
1689  NewAccess->setDefiningAccess(Definition);
1690  return NewAccess;
1691 }
1692 
1693 // Return true if the instruction has ordering constraints.
1694 // Note specifically that this only considers stores and loads
1695 // because others are still considered ModRef by getModRefInfo.
1696 static inline bool isOrdered(const Instruction *I) {
1697  if (auto *SI = dyn_cast<StoreInst>(I)) {
1698  if (!SI->isUnordered())
1699  return true;
1700  } else if (auto *LI = dyn_cast<LoadInst>(I)) {
1701  if (!LI->isUnordered())
1702  return true;
1703  }
1704  return false;
1705 }
1706 
1707 /// Helper function to create new memory accesses
1708 template <typename AliasAnalysisType>
1709 MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I,
1710  AliasAnalysisType *AAP,
1711  const MemoryUseOrDef *Template) {
1712  // The assume intrinsic has a control dependency which we model by claiming
1713  // that it writes arbitrarily. Ignore that fake memory dependency here.
1714  // FIXME: Replace this special casing with a more accurate modelling of
1715  // assume's control dependency.
1716  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
1717  if (II->getIntrinsicID() == Intrinsic::assume)
1718  return nullptr;
1719 
1720  bool Def, Use;
1721  if (Template) {
1722  Def = dyn_cast_or_null<MemoryDef>(Template) != nullptr;
1723  Use = dyn_cast_or_null<MemoryUse>(Template) != nullptr;
1724 #if !defined(NDEBUG)
1725  ModRefInfo ModRef = AAP->getModRefInfo(I, None);
1726  bool DefCheck, UseCheck;
1727  DefCheck = isModSet(ModRef) || isOrdered(I);
1728  UseCheck = isRefSet(ModRef);
1729  assert(Def == DefCheck && (Def || Use == UseCheck) && "Invalid template");
1730 #endif
1731  } else {
1732  // Find out what affect this instruction has on memory.
1733  ModRefInfo ModRef = AAP->getModRefInfo(I, None);
1734  // The isOrdered check is used to ensure that volatiles end up as defs
1735  // (atomics end up as ModRef right now anyway). Until we separate the
1736  // ordering chain from the memory chain, this enables people to see at least
1737  // some relative ordering to volatiles. Note that getClobberingMemoryAccess
1738  // will still give an answer that bypasses other volatile loads. TODO:
1739  // Separate memory aliasing and ordering into two different chains so that
1740  // we can precisely represent both "what memory will this read/write/is
1741  // clobbered by" and "what instructions can I move this past".
1742  Def = isModSet(ModRef) || isOrdered(I);
1743  Use = isRefSet(ModRef);
1744  }
1745 
1746  // It's possible for an instruction to not modify memory at all. During
1747  // construction, we ignore them.
1748  if (!Def && !Use)
1749  return nullptr;
1750 
1751  MemoryUseOrDef *MUD;
1752  if (Def)
1753  MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++);
1754  else
1755  MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent());
1756  ValueToMemoryAccess[I] = MUD;
1757  return MUD;
1758 }
1759 
1760 /// Returns true if \p Replacer dominates \p Replacee .
1761 bool MemorySSA::dominatesUse(const MemoryAccess *Replacer,
1762  const MemoryAccess *Replacee) const {
1763  if (isa<MemoryUseOrDef>(Replacee))
1764  return DT->dominates(Replacer->getBlock(), Replacee->getBlock());
1765  const auto *MP = cast<MemoryPhi>(Replacee);
1766  // For a phi node, the use occurs in the predecessor block of the phi node.
1767  // Since we may occur multiple times in the phi node, we have to check each
1768  // operand to ensure Replacer dominates each operand where Replacee occurs.
1769  for (const Use &Arg : MP->operands()) {
1770  if (Arg.get() != Replacee &&
1771  !DT->dominates(Replacer->getBlock(), MP->getIncomingBlock(Arg)))
1772  return false;
1773  }
1774  return true;
1775 }
1776 
1777 /// Properly remove \p MA from all of MemorySSA's lookup tables.
1779  assert(MA->use_empty() &&
1780  "Trying to remove memory access that still has uses");
1781  BlockNumbering.erase(MA);
1782  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1783  MUD->setDefiningAccess(nullptr);
1784  // Invalidate our walker's cache if necessary
1785  if (!isa<MemoryUse>(MA))
1786  getWalker()->invalidateInfo(MA);
1787 
1788  Value *MemoryInst;
1789  if (const auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1790  MemoryInst = MUD->getMemoryInst();
1791  else
1792  MemoryInst = MA->getBlock();
1793 
1794  auto VMA = ValueToMemoryAccess.find(MemoryInst);
1795  if (VMA->second == MA)
1796  ValueToMemoryAccess.erase(VMA);
1797 }
1798 
1799 /// Properly remove \p MA from all of MemorySSA's lists.
1800 ///
1801 /// Because of the way the intrusive list and use lists work, it is important to
1802 /// do removal in the right order.
1803 /// ShouldDelete defaults to true, and will cause the memory access to also be
1804 /// deleted, not just removed.
1805 void MemorySSA::removeFromLists(MemoryAccess *MA, bool ShouldDelete) {
1806  BasicBlock *BB = MA->getBlock();
1807  // The access list owns the reference, so we erase it from the non-owning list
1808  // first.
1809  if (!isa<MemoryUse>(MA)) {
1810  auto DefsIt = PerBlockDefs.find(BB);
1811  std::unique_ptr<DefsList> &Defs = DefsIt->second;
1812  Defs->remove(*MA);
1813  if (Defs->empty())
1814  PerBlockDefs.erase(DefsIt);
1815  }
1816 
1817  // The erase call here will delete it. If we don't want it deleted, we call
1818  // remove instead.
1819  auto AccessIt = PerBlockAccesses.find(BB);
1820  std::unique_ptr<AccessList> &Accesses = AccessIt->second;
1821  if (ShouldDelete)
1822  Accesses->erase(MA);
1823  else
1824  Accesses->remove(MA);
1825 
1826  if (Accesses->empty()) {
1827  PerBlockAccesses.erase(AccessIt);
1828  BlockNumberingValid.erase(BB);
1829  }
1830 }
1831 
1833  MemorySSAAnnotatedWriter Writer(this);
1834  F.print(OS, &Writer);
1835 }
1836 
1837 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1839 #endif
1840 
1842  verifyDefUses(F);
1844  verifyOrdering(F);
1846  // Previously, the verification used to also verify that the clobberingAccess
1847  // cached by MemorySSA is the same as the clobberingAccess found at a later
1848  // query to AA. This does not hold true in general due to the current fragility
1849  // of BasicAA which has arbitrary caps on the things it analyzes before giving
1850  // up. As a result, transformations that are correct, will lead to BasicAA
1851  // returning different Alias answers before and after that transformation.
1852  // Invalidating MemorySSA is not an option, as the results in BasicAA can be so
1853  // random, in the worst case we'd need to rebuild MemorySSA from scratch after
1854  // every transformation, which defeats the purpose of using it. For such an
1855  // example, see test4 added in D51960.
1856 }
1857 
1858 /// Verify that all of the blocks we believe to have valid domination numbers
1859 /// actually have valid domination numbers.
1861 #ifndef NDEBUG
1862  if (BlockNumberingValid.empty())
1863  return;
1864 
1865  SmallPtrSet<const BasicBlock *, 16> ValidBlocks = BlockNumberingValid;
1866  for (const BasicBlock &BB : F) {
1867  if (!ValidBlocks.count(&BB))
1868  continue;
1869 
1870  ValidBlocks.erase(&BB);
1871 
1872  const AccessList *Accesses = getBlockAccesses(&BB);
1873  // It's correct to say an empty block has valid numbering.
1874  if (!Accesses)
1875  continue;
1876 
1877  // Block numbering starts at 1.
1878  unsigned long LastNumber = 0;
1879  for (const MemoryAccess &MA : *Accesses) {
1880  auto ThisNumberIter = BlockNumbering.find(&MA);
1881  assert(ThisNumberIter != BlockNumbering.end() &&
1882  "MemoryAccess has no domination number in a valid block!");
1883 
1884  unsigned long ThisNumber = ThisNumberIter->second;
1885  assert(ThisNumber > LastNumber &&
1886  "Domination numbers should be strictly increasing!");
1887  LastNumber = ThisNumber;
1888  }
1889  }
1890 
1891  assert(ValidBlocks.empty() &&
1892  "All valid BasicBlocks should exist in F -- dangling pointers?");
1893 #endif
1894 }
1895 
1896 /// Verify that the order and existence of MemoryAccesses matches the
1897 /// order and existence of memory affecting instructions.
1899 #ifndef NDEBUG
1900  // Walk all the blocks, comparing what the lookups think and what the access
1901  // lists think, as well as the order in the blocks vs the order in the access
1902  // lists.
1903  SmallVector<MemoryAccess *, 32> ActualAccesses;
1905  for (BasicBlock &B : F) {
1906  const AccessList *AL = getBlockAccesses(&B);
1907  const auto *DL = getBlockDefs(&B);
1908  MemoryAccess *Phi = getMemoryAccess(&B);
1909  if (Phi) {
1910  ActualAccesses.push_back(Phi);
1911  ActualDefs.push_back(Phi);
1912  }
1913 
1914  for (Instruction &I : B) {
1915  MemoryAccess *MA = getMemoryAccess(&I);
1916  assert((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&
1917  "We have memory affecting instructions "
1918  "in this block but they are not in the "
1919  "access list or defs list");
1920  if (MA) {
1921  ActualAccesses.push_back(MA);
1922  if (isa<MemoryDef>(MA))
1923  ActualDefs.push_back(MA);
1924  }
1925  }
1926  // Either we hit the assert, really have no accesses, or we have both
1927  // accesses and an access list.
1928  // Same with defs.
1929  if (!AL && !DL)
1930  continue;
1931  assert(AL->size() == ActualAccesses.size() &&
1932  "We don't have the same number of accesses in the block as on the "
1933  "access list");
1934  assert((DL || ActualDefs.size() == 0) &&
1935  "Either we should have a defs list, or we should have no defs");
1936  assert((!DL || DL->size() == ActualDefs.size()) &&
1937  "We don't have the same number of defs in the block as on the "
1938  "def list");
1939  auto ALI = AL->begin();
1940  auto AAI = ActualAccesses.begin();
1941  while (ALI != AL->end() && AAI != ActualAccesses.end()) {
1942  assert(&*ALI == *AAI && "Not the same accesses in the same order");
1943  ++ALI;
1944  ++AAI;
1945  }
1946  ActualAccesses.clear();
1947  if (DL) {
1948  auto DLI = DL->begin();
1949  auto ADI = ActualDefs.begin();
1950  while (DLI != DL->end() && ADI != ActualDefs.end()) {
1951  assert(&*DLI == *ADI && "Not the same defs in the same order");
1952  ++DLI;
1953  ++ADI;
1954  }
1955  }
1956  ActualDefs.clear();
1957  }
1958 #endif
1959 }
1960 
1961 /// Verify the domination properties of MemorySSA by checking that each
1962 /// definition dominates all of its uses.
1964 #ifndef NDEBUG
1965  for (BasicBlock &B : F) {
1966  // Phi nodes are attached to basic blocks
1967  if (MemoryPhi *MP = getMemoryAccess(&B))
1968  for (const Use &U : MP->uses())
1969  assert(dominates(MP, U) && "Memory PHI does not dominate it's uses");
1970 
1971  for (Instruction &I : B) {
1972  MemoryAccess *MD = dyn_cast_or_null<MemoryDef>(getMemoryAccess(&I));
1973  if (!MD)
1974  continue;
1975 
1976  for (const Use &U : MD->uses())
1977  assert(dominates(MD, U) && "Memory Def does not dominate it's uses");
1978  }
1979  }
1980 #endif
1981 }
1982 
1983 /// Verify the def-use lists in MemorySSA, by verifying that \p Use
1984 /// appears in the use list of \p Def.
1985 void MemorySSA::verifyUseInDefs(MemoryAccess *Def, MemoryAccess *Use) const {
1986 #ifndef NDEBUG
1987  // The live on entry use may cause us to get a NULL def here
1988  if (!Def)
1989  assert(isLiveOnEntryDef(Use) &&
1990  "Null def but use not point to live on entry def");
1991  else
1992  assert(is_contained(Def->users(), Use) &&
1993  "Did not find use in def's use list");
1994 #endif
1995 }
1996 
1997 /// Verify the immediate use information, by walking all the memory
1998 /// accesses and verifying that, for each use, it appears in the
1999 /// appropriate def's use list
2001 #ifndef NDEBUG
2002  for (BasicBlock &B : F) {
2003  // Phi nodes are attached to basic blocks
2004  if (MemoryPhi *Phi = getMemoryAccess(&B)) {
2005  assert(Phi->getNumOperands() == static_cast<unsigned>(std::distance(
2006  pred_begin(&B), pred_end(&B))) &&
2007  "Incomplete MemoryPhi Node");
2008  for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
2009  verifyUseInDefs(Phi->getIncomingValue(I), Phi);
2010  assert(find(predecessors(&B), Phi->getIncomingBlock(I)) !=
2011  pred_end(&B) &&
2012  "Incoming phi block not a block predecessor");
2013  }
2014  }
2015 
2016  for (Instruction &I : B) {
2017  if (MemoryUseOrDef *MA = getMemoryAccess(&I)) {
2018  verifyUseInDefs(MA->getDefiningAccess(), MA);
2019  }
2020  }
2021  }
2022 #endif
2023 }
2024 
2025 /// Perform a local numbering on blocks so that instruction ordering can be
2026 /// determined in constant time.
2027 /// TODO: We currently just number in order. If we numbered by N, we could
2028 /// allow at least N-1 sequences of insertBefore or insertAfter (and at least
2029 /// log2(N) sequences of mixed before and after) without needing to invalidate
2030 /// the numbering.
2031 void MemorySSA::renumberBlock(const BasicBlock *B) const {
2032  // The pre-increment ensures the numbers really start at 1.
2033  unsigned long CurrentNumber = 0;
2034  const AccessList *AL = getBlockAccesses(B);
2035  assert(AL != nullptr && "Asking to renumber an empty block");
2036  for (const auto &I : *AL)
2037  BlockNumbering[&I] = ++CurrentNumber;
2038  BlockNumberingValid.insert(B);
2039 }
2040 
2041 /// Determine, for two memory accesses in the same block,
2042 /// whether \p Dominator dominates \p Dominatee.
2043 /// \returns True if \p Dominator dominates \p Dominatee.
2045  const MemoryAccess *Dominatee) const {
2046  const BasicBlock *DominatorBlock = Dominator->getBlock();
2047 
2048  assert((DominatorBlock == Dominatee->getBlock()) &&
2049  "Asking for local domination when accesses are in different blocks!");
2050  // A node dominates itself.
2051  if (Dominatee == Dominator)
2052  return true;
2053 
2054  // When Dominatee is defined on function entry, it is not dominated by another
2055  // memory access.
2056  if (isLiveOnEntryDef(Dominatee))
2057  return false;
2058 
2059  // When Dominator is defined on function entry, it dominates the other memory
2060  // access.
2061  if (isLiveOnEntryDef(Dominator))
2062  return true;
2063 
2064  if (!BlockNumberingValid.count(DominatorBlock))
2065  renumberBlock(DominatorBlock);
2066 
2067  unsigned long DominatorNum = BlockNumbering.lookup(Dominator);
2068  // All numbers start with 1
2069  assert(DominatorNum != 0 && "Block was not numbered properly");
2070  unsigned long DominateeNum = BlockNumbering.lookup(Dominatee);
2071  assert(DominateeNum != 0 && "Block was not numbered properly");
2072  return DominatorNum < DominateeNum;
2073 }
2074 
2075 bool MemorySSA::dominates(const MemoryAccess *Dominator,
2076  const MemoryAccess *Dominatee) const {
2077  if (Dominator == Dominatee)
2078  return true;
2079 
2080  if (isLiveOnEntryDef(Dominatee))
2081  return false;
2082 
2083  if (Dominator->getBlock() != Dominatee->getBlock())
2084  return DT->dominates(Dominator->getBlock(), Dominatee->getBlock());
2085  return locallyDominates(Dominator, Dominatee);
2086 }
2087 
2088 bool MemorySSA::dominates(const MemoryAccess *Dominator,
2089  const Use &Dominatee) const {
2090  if (MemoryPhi *MP = dyn_cast<MemoryPhi>(Dominatee.getUser())) {
2091  BasicBlock *UseBB = MP->getIncomingBlock(Dominatee);
2092  // The def must dominate the incoming block of the phi.
2093  if (UseBB != Dominator->getBlock())
2094  return DT->dominates(Dominator->getBlock(), UseBB);
2095  // If the UseBB and the DefBB are the same, compare locally.
2096  return locallyDominates(Dominator, cast<MemoryAccess>(Dominatee));
2097  }
2098  // If it's not a PHI node use, the normal dominates can already handle it.
2099  return dominates(Dominator, cast<MemoryAccess>(Dominatee.getUser()));
2100 }
2101 
2102 const static char LiveOnEntryStr[] = "liveOnEntry";
2103 
2105  switch (getValueID()) {
2106  case MemoryPhiVal: return static_cast<const MemoryPhi *>(this)->print(OS);
2107  case MemoryDefVal: return static_cast<const MemoryDef *>(this)->print(OS);
2108  case MemoryUseVal: return static_cast<const MemoryUse *>(this)->print(OS);
2109  }
2110  llvm_unreachable("invalid value id");
2111 }
2112 
2114  MemoryAccess *UO = getDefiningAccess();
2115 
2116  auto printID = [&OS](MemoryAccess *A) {
2117  if (A && A->getID())
2118  OS << A->getID();
2119  else
2120  OS << LiveOnEntryStr;
2121  };
2122 
2123  OS << getID() << " = MemoryDef(";
2124  printID(UO);
2125  OS << ")";
2126 
2127  if (isOptimized()) {
2128  OS << "->";
2129  printID(getOptimized());
2130 
2131  if (Optional<AliasResult> AR = getOptimizedAccessType())
2132  OS << " " << *AR;
2133  }
2134 }
2135 
2137  bool First = true;
2138  OS << getID() << " = MemoryPhi(";
2139  for (const auto &Op : operands()) {
2140  BasicBlock *BB = getIncomingBlock(Op);
2141  MemoryAccess *MA = cast<MemoryAccess>(Op);
2142  if (!First)
2143  OS << ',';
2144  else
2145  First = false;
2146 
2147  OS << '{';
2148  if (BB->hasName())
2149  OS << BB->getName();
2150  else
2151  BB->printAsOperand(OS, false);
2152  OS << ',';
2153  if (unsigned ID = MA->getID())
2154  OS << ID;
2155  else
2156  OS << LiveOnEntryStr;
2157  OS << '}';
2158  }
2159  OS << ')';
2160 }
2161 
2163  MemoryAccess *UO = getDefiningAccess();
2164  OS << "MemoryUse(";
2165  if (UO && UO->getID())
2166  OS << UO->getID();
2167  else
2168  OS << LiveOnEntryStr;
2169  OS << ')';
2170 
2171  if (Optional<AliasResult> AR = getOptimizedAccessType())
2172  OS << " " << *AR;
2173 }
2174 
2175 void MemoryAccess::dump() const {
2176 // Cannot completely remove virtual function even in release mode.
2177 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2178  print(dbgs());
2179  dbgs() << "\n";
2180 #endif
2181 }
2182 
2184 
2187 }
2188 
2190  AU.setPreservesAll();
2191  AU.addRequired<MemorySSAWrapperPass>();
2192 }
2193 
2195  auto &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA();
2196  MSSA.print(dbgs());
2197  if (VerifyMemorySSA)
2198  MSSA.verifyMemorySSA();
2199  return false;
2200 }
2201 
2202 AnalysisKey MemorySSAAnalysis::Key;
2203 
2206  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
2207  auto &AA = AM.getResult<AAManager>(F);
2208  return MemorySSAAnalysis::Result(llvm::make_unique<MemorySSA>(F, &AA, &DT));
2209 }
2210 
2213  OS << "MemorySSA for function: " << F.getName() << "\n";
2214  AM.getResult<MemorySSAAnalysis>(F).getMSSA().print(OS);
2215 
2216  return PreservedAnalyses::all();
2217 }
2218 
2221  AM.getResult<MemorySSAAnalysis>(F).getMSSA().verifyMemorySSA();
2222 
2223  return PreservedAnalyses::all();
2224 }
2225 
2226 char MemorySSAWrapperPass::ID = 0;
2227 
2230 }
2231 
2232 void MemorySSAWrapperPass::releaseMemory() { MSSA.reset(); }
2233 
2235  AU.setPreservesAll();
2238 }
2239 
2241  auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2242  auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
2243  MSSA.reset(new MemorySSA(F, &AA, &DT));
2244  return false;
2245 }
2246 
2247 void MemorySSAWrapperPass::verifyAnalysis() const { MSSA->verifyMemorySSA(); }
2248 
2250  MSSA->print(OS);
2251 }
2252 
2254 
2255 /// Walk the use-def chains starting at \p StartingAccess and find
2256 /// the MemoryAccess that actually clobbers Loc.
2257 ///
2258 /// \returns our clobbering memory access
2259 template <typename AliasAnalysisType>
2260 MemoryAccess *
2261 MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
2262  MemoryAccess *StartingAccess, const MemoryLocation &Loc,
2263  unsigned &UpwardWalkLimit) {
2264  if (isa<MemoryPhi>(StartingAccess))
2265  return StartingAccess;
2266 
2267  auto *StartingUseOrDef = cast<MemoryUseOrDef>(StartingAccess);
2268  if (MSSA->isLiveOnEntryDef(StartingUseOrDef))
2269  return StartingUseOrDef;
2270 
2271  Instruction *I = StartingUseOrDef->getMemoryInst();
2272 
2273  // Conservatively, fences are always clobbers, so don't perform the walk if we
2274  // hit a fence.
2275  if (!isa<CallBase>(I) && I->isFenceLike())
2276  return StartingUseOrDef;
2277 
2278  UpwardsMemoryQuery Q;
2279  Q.OriginalAccess = StartingUseOrDef;
2280  Q.StartingLoc = Loc;
2281  Q.Inst = I;
2282  Q.IsCall = false;
2283 
2284  // Unlike the other function, do not walk to the def of a def, because we are
2285  // handed something we already believe is the clobbering access.
2286  // We never set SkipSelf to true in Q in this method.
2287  MemoryAccess *DefiningAccess = isa<MemoryUse>(StartingUseOrDef)
2288  ? StartingUseOrDef->getDefiningAccess()
2289  : StartingUseOrDef;
2290 
2291  MemoryAccess *Clobber =
2292  Walker.findClobber(DefiningAccess, Q, UpwardWalkLimit);
2293  LLVM_DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ");
2294  LLVM_DEBUG(dbgs() << *StartingUseOrDef << "\n");
2295  LLVM_DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is ");
2296  LLVM_DEBUG(dbgs() << *Clobber << "\n");
2297  return Clobber;
2298 }
2299 
2300 template <typename AliasAnalysisType>
2301 MemoryAccess *
2302 MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
2303  MemoryAccess *MA, unsigned &UpwardWalkLimit, bool SkipSelf) {
2304  auto *StartingAccess = dyn_cast<MemoryUseOrDef>(MA);
2305  // If this is a MemoryPhi, we can't do anything.
2306  if (!StartingAccess)
2307  return MA;
2308 
2309  bool IsOptimized = false;
2310 
2311  // If this is an already optimized use or def, return the optimized result.
2312  // Note: Currently, we store the optimized def result in a separate field,
2313  // since we can't use the defining access.
2314  if (StartingAccess->isOptimized()) {
2315  if (!SkipSelf || !isa<MemoryDef>(StartingAccess))
2316  return StartingAccess->getOptimized();
2317  IsOptimized = true;
2318  }
2319 
2320  const Instruction *I = StartingAccess->getMemoryInst();
2321  // We can't sanely do anything with a fence, since they conservatively clobber
2322  // all memory, and have no locations to get pointers from to try to
2323  // disambiguate.
2324  if (!isa<CallBase>(I) && I->isFenceLike())
2325  return StartingAccess;
2326 
2327  UpwardsMemoryQuery Q(I, StartingAccess);
2328 
2329  if (isUseTriviallyOptimizableToLiveOnEntry(*Walker.getAA(), I)) {
2330  MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
2331  StartingAccess->setOptimized(LiveOnEntry);
2332  StartingAccess->setOptimizedAccessType(None);
2333  return LiveOnEntry;
2334  }
2335 
2336  MemoryAccess *OptimizedAccess;
2337  if (!IsOptimized) {
2338  // Start with the thing we already think clobbers this location
2339  MemoryAccess *DefiningAccess = StartingAccess->getDefiningAccess();
2340 
2341  // At this point, DefiningAccess may be the live on entry def.
2342  // If it is, we will not get a better result.
2343  if (MSSA->isLiveOnEntryDef(DefiningAccess)) {
2344  StartingAccess->setOptimized(DefiningAccess);
2345  StartingAccess->setOptimizedAccessType(None);
2346  return DefiningAccess;
2347  }
2348 
2349  OptimizedAccess = Walker.findClobber(DefiningAccess, Q, UpwardWalkLimit);
2350  StartingAccess->setOptimized(OptimizedAccess);
2351  if (MSSA->isLiveOnEntryDef(OptimizedAccess))
2352  StartingAccess->setOptimizedAccessType(None);
2353  else if (Q.AR == MustAlias)
2354  StartingAccess->setOptimizedAccessType(MustAlias);
2355  } else
2356  OptimizedAccess = StartingAccess->getOptimized();
2357 
2358  LLVM_DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ");
2359  LLVM_DEBUG(dbgs() << *StartingAccess << "\n");
2360  LLVM_DEBUG(dbgs() << "Optimized Memory SSA clobber for " << *I << " is ");
2361  LLVM_DEBUG(dbgs() << *OptimizedAccess << "\n");
2362 
2363  MemoryAccess *Result;
2364  if (SkipSelf && isa<MemoryPhi>(OptimizedAccess) &&
2365  isa<MemoryDef>(StartingAccess) && UpwardWalkLimit) {
2366  assert(isa<MemoryDef>(Q.OriginalAccess));
2367  Q.SkipSelfAccess = true;
2368  Result = Walker.findClobber(OptimizedAccess, Q, UpwardWalkLimit);
2369  } else
2370  Result = OptimizedAccess;
2371 
2372  LLVM_DEBUG(dbgs() << "Result Memory SSA clobber [SkipSelf = " << SkipSelf);
2373  LLVM_DEBUG(dbgs() << "] for " << *I << " is " << *Result << "\n");
2374 
2375  return Result;
2376 }
2377 
2378 MemoryAccess *
2380  if (auto *Use = dyn_cast<MemoryUseOrDef>(MA))
2381  return Use->getDefiningAccess();
2382  return MA;
2383 }
2384 
2386  MemoryAccess *StartingAccess, const MemoryLocation &) {
2387  if (auto *Use = dyn_cast<MemoryUseOrDef>(StartingAccess))
2388  return Use->getDefiningAccess();
2389  return StartingAccess;
2390 }
2391 
2392 void MemoryPhi::deleteMe(DerivedUser *Self) {
2393  delete static_cast<MemoryPhi *>(Self);
2394 }
2395 
2396 void MemoryDef::deleteMe(DerivedUser *Self) {
2397  delete static_cast<MemoryDef *>(Self);
2398 }
2399 
2400 void MemoryUse::deleteMe(DerivedUser *Self) {
2401  delete static_cast<MemoryUse *>(Self);
2402 }
MemorySSAWalker * getWalker()
Definition: MemorySSA.cpp:1542
bool runOnFunction(Function &) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass...
Definition: MemorySSA.cpp:2240
The access may reference and may modify the value stored in memory.
uint64_t CallInst * C
void initializeMemorySSAWrapperPassPass(PassRegistry &)
AccessList * getWritableBlockAccesses(const BasicBlock *BB) const
Definition: MemorySSA.h:799
reference emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:645
typename std::vector< DomTreeNodeBase *>::const_iterator const_iterator
iterator_range< use_iterator > uses()
Definition: Value.h:354
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Value * getPointerOperand(Value *V)
A helper function that returns the pointer operand of a load, store or GEP instruction.
void dropAllReferences()
Drop all references to operands.
Definition: User.h:294
Atomic ordering constants.
bool VerifyMemorySSA
Enables verification of MemorySSA.
Definition: MemorySSA.cpp:82
bool isFenceLike() const
Return true if this instruction behaves like a memory fence: it can load or store to memory location ...
Definition: Instruction.h:554
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:769
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2136
This class represents lattice values for constants.
Definition: AllocatorList.h:23
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds...
Definition: Compiler.h:473
bool dominates(const MemoryAccess *A, const MemoryAccess *B) const
Given two memory accesses in potentially different blocks, determine whether MemoryAccess A dominates...
Definition: MemorySSA.cpp:2075
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:65
void push_back(reference Node)
Insert a node at the back; never copies.
Definition: simple_ilist.h:147
formatted_raw_ostream - A raw_ostream that wraps another one and keeps track of line and column posit...
This class provides various memory handling functions that manipulate MemoryBlock instances...
Definition: Memory.h:46
const AccessList * getBlockAccesses(const BasicBlock *BB) const
Return the list of MemoryAccess&#39;s for a given basic block.
Definition: MemorySSA.h:755
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: MemorySSA.cpp:2189
The two locations do not alias at all.
Definition: AliasAnalysis.h:84
Extension point for the Value hierarchy.
Definition: DerivedUser.h:27
Represents a read-write access to memory, whether it is a must-alias, or a may-alias.
Definition: MemorySSA.h:372
AtomicOrdering getOrdering() const
Returns the ordering constraint of this load instruction.
Definition: Instructions.h:247
static const char LiveOnEntryStr[]
Definition: MemorySSA.cpp:2102
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:709
unsigned second
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: MemorySSA.cpp:2234
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1185
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1014
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:230
F(f)
block Block Frequency true
An instruction for reading from memory.
Definition: Instructions.h:167
memoryssa
Definition: MemorySSA.cpp:64
LLVM_READONLY APFloat maximum(const APFloat &A, const APFloat &B)
Implements IEEE 754-2018 maximum semantics.
Definition: APFloat.h:1261
This defines the Use class.
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2113
MemorySSA(Function &, AliasAnalysis *, DominatorTree *)
Definition: MemorySSA.cpp:1205
LLVMContext & getContext() const
Get the context in which this basic block lives.
Definition: BasicBlock.cpp:32
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:343
INITIALIZE_PASS_BEGIN(MemorySSAWrapperPass, "memoryssa", "Memory SSA", false, true) INITIALIZE_PASS_END(MemorySSAWrapperPass
OptimizeUses(MemorySSA *MSSA, CachingWalker< BatchAAResults > *Walker, BatchAAResults *BAA, DominatorTree *DT)
Definition: MemorySSA.cpp:1256
std::pair< iterator, bool > insert(const std::pair< KeyT, ValueT > &KV)
Definition: DenseMap.h:221
Represents read-only accesses to memory.
Definition: MemorySSA.h:316
This class is a batch walker of all MemoryUse&#39;s in the program, and points their defining access at t...
Definition: MemorySSA.cpp:1254
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:50
Legacy analysis pass which computes MemorySSA.
Definition: MemorySSA.h:957
bool isVolatile() const
Return true if this is a load from a volatile memory location.
Definition: Instructions.h:231
static bool lifetimeEndsAt(MemoryDef *MD, const MemoryLocation &Loc, BatchAAResults &AA)
Definition: MemorySSA.cpp:348
void renamePass(BasicBlock *BB, MemoryAccess *IncomingVal, SmallPtrSetImpl< BasicBlock *> &Visited)
Definition: MemorySSA.h:818
A Use represents the edge between a Value definition and its users.
Definition: Use.h:55
void setDefiningBlocks(const SmallPtrSetImpl< BasicBlock *> &Blocks)
Give the IDF calculator the set of blocks in which the value is defined.
static bool defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU, AliasAnalysis &AA)
Definition: MemorySSA.cpp:317
MemorySSAAnnotatedWriter(const MemorySSA *M)
Definition: MemorySSA.cpp:98
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:41
Encapsulates MemorySSA, including all data associated with memory accesses.
Definition: MemorySSA.h:700
const DefsList * getBlockDefs(const BasicBlock *BB) const
Return the list of MemoryDef&#39;s and MemoryPhi&#39;s for a given basic block.
Definition: MemorySSA.h:763
void insertIntoListsForBlock(MemoryAccess *, const BasicBlock *, InsertionPlace)
Definition: MemorySSA.cpp:1574
static bool isOrdered(const Instruction *I)
Definition: MemorySSA.cpp:1696
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:849
APInt operator*(APInt a, uint64_t RHS)
Definition: APInt.h:2090
void verifyDefUses(Function &F) const
Verify the immediate use information, by walking all the memory accesses and verifying that...
Definition: MemorySSA.cpp:2000
void verifyAnalysis() const override
verifyAnalysis() - This member can be implemented by a analysis pass to check state of analysis infor...
Definition: MemorySSA.cpp:2247
A simple intrusive list implementation.
Definition: simple_ilist.h:78
LLVM_NODISCARD bool isMustSet(const ModRefInfo MRI)
User * getUser() const LLVM_READONLY
Returns the User that contains this Use.
Definition: Use.cpp:40
#define F(x, y, z)
Definition: MD5.cpp:55
static int getID(struct InternalInstruction *insn, const void *miiArg)
MemoryUseOrDef * getMemoryAccess(const Instruction *I) const
Given a memory Mod/Ref&#39;ing instruction, get the MemorySSA access associated with it.
Definition: MemorySSA.h:717
upward_defs_iterator upward_defs_end()
Definition: MemorySSA.h:1240
early cse memssa
Definition: EarlyCSE.cpp:1372
Memory SSA
Definition: MemorySSA.cpp:64
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:234
This class is a wrapper over an AAResults, and it is intended to be used only when there are no IR ch...
void emitBasicBlockStartAnnot(const BasicBlock *BB, formatted_raw_ostream &OS) override
emitBasicBlockStartAnnot - This may be implemented to emit a string right after the basic block label...
Definition: MemorySSA.cpp:100
void dump() const
Definition: MemorySSA.cpp:1838
static cl::opt< bool, true > VerifyMemorySSAX("verify-memoryssa", cl::location(VerifyMemorySSA), cl::Hidden, cl::desc("Enable verification of MemorySSA."))
This is the generic walker interface for walkers of MemorySSA.
Definition: MemorySSA.h:988
CRTP base class which implements the entire standard iterator facade in terms of a minimal subset of ...
Definition: iterator.h:67
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
bool isAtLeastOrStrongerThan(AtomicOrdering ao, AtomicOrdering other)
An assembly annotator class to print Memory SSA information in comments.
Definition: MemorySSA.cpp:92
void removeFromLookups(MemoryAccess *)
Properly remove MA from all of MemorySSA&#39;s lookup tables.
Definition: MemorySSA.cpp:1778
NodeT * getBlock() const
#define P(N)
static MemoryLocation get(const LoadInst *LI)
Return a location with information about the memory reference by the given instruction.
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:427
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
MemorySSAWalker * getSkipSelfWalker()
Definition: MemorySSA.cpp:1557
bool hasName() const
Definition: Value.h:250
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
DomTreeNodeBase * getIDom() const
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
LLVM_NODISCARD bool empty() const
Definition: SmallPtrSet.h:91
A manager for alias analyses.
std::pair< iterator, bool > insert(const ValueT &V)
Definition: DenseSet.h:187
static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS)
Definition: MemorySSA.cpp:206
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:370
early cse Early CSE w MemorySSA
Definition: EarlyCSE.cpp:1372
void dump() const
Definition: MemorySSA.cpp:2175
Interval::pred_iterator pred_begin(Interval *I)
pred_begin/pred_end - define methods so that Intervals may be used just like BasicBlocks can with the...
Definition: Interval.h:112
InsertionPlace
Used in various insertion functions to specify whether we are talking about the beginning or end of a...
Definition: MemorySSA.h:785
Represent the analysis usage information of a pass.
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2104
#define LLVM_ATTRIBUTE_UNUSED
Definition: Compiler.h:159
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:284
amdgpu Simplify well known AMD library false FunctionCallee Value * Arg
Interval::pred_iterator pred_end(Interval *I)
Definition: Interval.h:115
void verifyDomination(Function &F) const
Verify the domination properties of MemorySSA by checking that each definition dominates all of its u...
Definition: MemorySSA.cpp:1963
static void print(raw_ostream &Out, object::Archive::Kind Kind, T Val)
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:381
Memory true print Memory SSA Printer
Definition: MemorySSA.cpp:70
auto find_if(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range))
Provide wrappers to std::find_if which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1213
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Definition: MemorySSA.cpp:2219
auto find_if_not(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range))
Definition: STLExtras.h:1218
virtual void invalidateInfo(MemoryAccess *)
Given a memory access, invalidate anything this walker knows about that access.
Definition: MemorySSA.h:1046
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
size_t size() const
Definition: SmallVector.h:52
Compute iterated dominance frontiers using a linear time algorithm.
DomTreeNodeBase< NodeT > * getNode(const NodeT *BB) const
getNode - return the (Post)DominatorTree node for the specified basic block.
auto find(R &&Range, const T &Val) -> decltype(adl_begin(Range))
Provide wrappers to std::find which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1206
An intrusive list with ownership and callbacks specified/controlled by ilist_traits, only with API safe for polymorphic types.
Definition: ilist.h:388
void printAsOperand(raw_ostream &O, bool PrintType=true, const Module *M=nullptr) const
Print the name of this Value out to the specified raw_ostream.
Definition: AsmWriter.cpp:4288
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Memory true print Memory SSA static false cl::opt< unsigned > MaxCheckLimit("memssa-check-limit", cl::Hidden, cl::init(100), cl::desc("The maximum number of stores/phis MemorySSA" "will consider trying to walk past (default = 100)"))
MemoryUseOrDef * createDefinedAccess(Instruction *, MemoryAccess *, const MemoryUseOrDef *Template=nullptr)
Definition: MemorySSA.cpp:1681
void optimizeUses()
Optimize uses to point to their actual clobbering definitions.
Definition: MemorySSA.cpp:1459
The two locations may or may not alias. This is the least precise result.
Definition: AliasAnalysis.h:86
static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysisType &AA, const Instruction *I)
Definition: MemorySSA.cpp:363
Representation for a specific memory location.
The two locations precisely alias each other.
Definition: AliasAnalysis.h:90
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
void verifyOrdering(Function &F) const
Verify that the order and existence of MemoryAccesses matches the order and existence of memory affec...
Definition: MemorySSA.cpp:1898
void setDefiningAccess(MemoryAccess *DMA, bool Optimized=false, Optional< AliasResult > AR=MayAlias)
Definition: MemorySSA.h:296
unsigned getNumOperands() const
Definition: User.h:191
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:417
BlockVerifier::State From
void verifyMemorySSA() const
Verify that MemorySSA is self consistent (IE definitions dominate all uses, uses appear in the right ...
Definition: MemorySSA.cpp:1841
bool erase(PtrType Ptr)
erase - If the set contains the specified pointer, remove it and return true, otherwise return false...
Definition: SmallPtrSet.h:377
static LLVM_ATTRIBUTE_UNUSED void checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt, const MemoryLocation &StartLoc, const MemorySSA &MSSA, const UpwardsMemoryQuery &Query, AliasAnalysisType &AA, bool AllowImpreciseClobber=false)
Verifies that Start is clobbered by ClobberAt, and that nothing inbetween Start and ClobberAt can clo...
Definition: MemorySSA.cpp:388
void calculate(SmallVectorImpl< BasicBlock *> &IDFBlocks)
Calculate iterated dominance frontiers.
bool locallyDominates(const MemoryAccess *A, const MemoryAccess *B) const
Given two memory accesses in the same basic block, determine whether MemoryAccess A dominates MemoryA...
Definition: MemorySSA.cpp:2044
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:841
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:248
bool runOnFunction(Function &) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass...
Definition: MemorySSA.cpp:2194
An analysis that produces MemorySSA for a function.
Definition: MemorySSA.h:921
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:374
BasicBlock * getBlock() const
Definition: MemorySSA.h:156
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
pred_range predecessors(BasicBlock *BB)
Definition: CFG.h:124
#define MAP(n)
void emitInstructionAnnot(const Instruction *I, formatted_raw_ostream &OS) override
emitInstructionAnnot - This may be implemented to emit a string right before an instruction is emitte...
Definition: MemorySSA.cpp:106
MemoryAccess * getLiveOnEntryDef() const
Definition: MemorySSA.h:739
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2162
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:940
A range adaptor for a pair of iterators.
void removeFromLists(MemoryAccess *, bool ShouldDelete=true)
Properly remove MA from all of MemorySSA&#39;s lists.
Definition: MemorySSA.cpp:1805
Target - Wrapper for Target specific information.
void push_back(pointer val)
Definition: ilist.h:311
hash_code hash_combine(const Ts &...args)
Combine values into a single hash_code.
Definition: Hashing.h:600
Class that has the common methods + fields of memory uses/defs.
Definition: MemorySSA.h:244
void setPreservesAll()
Set by analyses that do not transform their input at all.
iterator_range< user_iterator > users()
Definition: Value.h:399
An opaque object representing a hash code.
Definition: Hashing.h:71
Instruction * getMemoryInst() const
Get the instruction that this MemoryUse represents.
Definition: MemorySSA.h:251
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:387
void initializeMemorySSAPrinterLegacyPassPass(PassRegistry &)
LLVM_NODISCARD bool isModSet(const ModRefInfo MRI)
MemorySSAWalker(MemorySSA *)
Definition: MemorySSA.cpp:2253
iterator_range< def_chain_iterator< T > > def_chain(T MA, MemoryAccess *UpTo=nullptr)
Definition: MemorySSA.h:1291
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:55
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
Definition: MemorySSA.cpp:2232
This file provides utility analysis objects describing memory locations.
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
#define I(x, y, z)
Definition: MD5.cpp:58
#define N
void moveTo(MemoryUseOrDef *What, BasicBlock *BB, AccessList::iterator Where)
Definition: MemorySSA.cpp:1650
MemoryAccess * getClobberingMemoryAccess(MemoryAccess *) override
Does the same thing as getClobberingMemoryAccess(const Instruction *I), but takes a MemoryAccess inst...
Definition: MemorySSA.cpp:2379
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:332
bool isLiveOnEntryDef(const MemoryAccess *MA) const
Return true if MA represents the live on entry value.
Definition: MemorySSA.h:735
AnalysisUsage & addRequiredTransitive()
iterator_range< df_iterator< T > > depth_first(const T &G)
MemoryAccess * getClobberingMemoryAccess(const Instruction *I)
Given a memory Mod/Ref/ModRef&#39;ing instruction, calling this will give you the nearest dominating Memo...
Definition: MemorySSA.h:1017
Determine the iterated dominance frontier, given a set of defining blocks, and optionally, a set of live-in blocks.
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Definition: MemorySSA.cpp:2211
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Result run(Function &F, FunctionAnalysisManager &AM)
Definition: MemorySSA.cpp:2204
static bool areLoadsReorderable(const LoadInst *Use, const LoadInst *MayClobber)
This does one-way checks to see if Use could theoretically be hoisted above MayClobber.
Definition: MemorySSA.cpp:219
LLVM Value Representation.
Definition: Value.h:72
static MemoryLocOrCall getTombstoneKey()
Definition: MemorySSA.cpp:187
succ_range successors(Instruction *I)
Definition: CFG.h:259
upward_defs_iterator upward_defs_begin(const MemoryAccessPair &Pair)
Definition: MemorySSA.h:1236
AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB)
unsigned getID() const
Used for debugging and tracking things about MemoryAccesses.
Definition: MemorySSA.h:661
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:45
static ClobberAlias instructionClobbersQuery(const MemoryDef *MD, const MemoryLocation &UseLoc, const Instruction *UseInst, AliasAnalysisType &AA)
Definition: MemorySSA.cpp:256
ModRefInfo
Flags indicating whether a memory access modifies or references memory.
static unsigned getHashValue(const MemoryLocOrCall &MLOC)
Definition: MemorySSA.cpp:191
This file exposes an interface to building/using memory SSA to walk memory instructions using a use/d...
hexagon cext opt
A container for analyses that lazily runs them and caches their results.
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:259
void setBlock(BasicBlock *BB)
Used by MemorySSA to change the block of a MemoryAccess when it is moved.
Definition: MemorySSA.h:209
LLVM_NODISCARD bool isModOrRefSet(const ModRefInfo MRI)
bool operator==(uint64_t V1, const APInt &V2)
Definition: APInt.h:1966
void verifyDominationNumbers(const Function &F) const
Verify that all of the blocks we believe to have valid domination numbers actually have valid dominat...
Definition: MemorySSA.cpp:1860
A wrapper pass to provide the legacy pass manager access to a suitably prepared AAResults object...
Represents phi nodes for memory accesses.
Definition: MemorySSA.h:478
void print(raw_ostream &) const
Definition: MemorySSA.cpp:1832
This header defines various interfaces for pass management in LLVM.
#define LLVM_DEBUG(X)
Definition: Debug.h:122
static MemoryLocOrCall getEmptyKey()
Definition: MemorySSA.cpp:183
void insertIntoListsBefore(MemoryAccess *, const BasicBlock *, AccessList::iterator)
Definition: MemorySSA.cpp:1606
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:70
bool use_empty() const
Definition: Value.h:322
LocationClass< Ty > location(Ty &L)
Definition: CommandLine.h:443
hexagon widen stores
reverse_iterator rbegin()
Definition: simple_ilist.h:121
std::pair< MemoryAccess *, MemoryLocation > MemoryAccessPair
Definition: MemorySSA.h:1067
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:43
const BasicBlock * getParent() const
Definition: Instruction.h:66
void print(raw_ostream &OS, const Module *M=nullptr) const override
print - Print out the internal state of the pass.
Definition: MemorySSA.cpp:2249
bool is_contained(R &&Range, const E &Element)
Wrapper function around std::find to detect if an element exists in a container.
Definition: STLExtras.h:1244
LLVM_NODISCARD bool isRefSet(const ModRefInfo MRI)