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
84 /// Enables memory ssa as a dependency for loop passes in legacy pass manager.
86  "enable-mssa-loop-dependency", cl::Hidden, cl::init(false),
87  cl::desc("Enable MemorySSA dependency for loop pass manager"));
88 
90  VerifyMemorySSAX("verify-memoryssa", cl::location(VerifyMemorySSA),
91  cl::Hidden, cl::desc("Enable verification of MemorySSA."));
92 
93 namespace llvm {
94 
95 /// An assembly annotator class to print Memory SSA information in
96 /// comments.
98  friend class MemorySSA;
99 
100  const MemorySSA *MSSA;
101 
102 public:
103  MemorySSAAnnotatedWriter(const MemorySSA *M) : MSSA(M) {}
104 
106  formatted_raw_ostream &OS) override {
107  if (MemoryAccess *MA = MSSA->getMemoryAccess(BB))
108  OS << "; " << *MA << "\n";
109  }
110 
112  formatted_raw_ostream &OS) override {
113  if (MemoryAccess *MA = MSSA->getMemoryAccess(I))
114  OS << "; " << *MA << "\n";
115  }
116 };
117 
118 } // end namespace llvm
119 
120 namespace {
121 
122 /// Our current alias analysis API differentiates heavily between calls and
123 /// non-calls, and functions called on one usually assert on the other.
124 /// This class encapsulates the distinction to simplify other code that wants
125 /// "Memory affecting instructions and related data" to use as a key.
126 /// For example, this class is used as a densemap key in the use optimizer.
127 class MemoryLocOrCall {
128 public:
129  bool IsCall = false;
130 
131  MemoryLocOrCall(MemoryUseOrDef *MUD)
132  : MemoryLocOrCall(MUD->getMemoryInst()) {}
133  MemoryLocOrCall(const MemoryUseOrDef *MUD)
134  : MemoryLocOrCall(MUD->getMemoryInst()) {}
135 
136  MemoryLocOrCall(Instruction *Inst) {
137  if (auto *C = dyn_cast<CallBase>(Inst)) {
138  IsCall = true;
139  Call = C;
140  } else {
141  IsCall = false;
142  // There is no such thing as a memorylocation for a fence inst, and it is
143  // unique in that regard.
144  if (!isa<FenceInst>(Inst))
145  Loc = MemoryLocation::get(Inst);
146  }
147  }
148 
149  explicit MemoryLocOrCall(const MemoryLocation &Loc) : Loc(Loc) {}
150 
151  const CallBase *getCall() const {
152  assert(IsCall);
153  return Call;
154  }
155 
156  MemoryLocation getLoc() const {
157  assert(!IsCall);
158  return Loc;
159  }
160 
161  bool operator==(const MemoryLocOrCall &Other) const {
162  if (IsCall != Other.IsCall)
163  return false;
164 
165  if (!IsCall)
166  return Loc == Other.Loc;
167 
168  if (Call->getCalledValue() != Other.Call->getCalledValue())
169  return false;
170 
171  return Call->arg_size() == Other.Call->arg_size() &&
172  std::equal(Call->arg_begin(), Call->arg_end(),
173  Other.Call->arg_begin());
174  }
175 
176 private:
177  union {
178  const CallBase *Call;
179  MemoryLocation Loc;
180  };
181 };
182 
183 } // end anonymous namespace
184 
185 namespace llvm {
186 
187 template <> struct DenseMapInfo<MemoryLocOrCall> {
188  static inline MemoryLocOrCall getEmptyKey() {
189  return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getEmptyKey());
190  }
191 
192  static inline MemoryLocOrCall getTombstoneKey() {
193  return MemoryLocOrCall(DenseMapInfo<MemoryLocation>::getTombstoneKey());
194  }
195 
196  static unsigned getHashValue(const MemoryLocOrCall &MLOC) {
197  if (!MLOC.IsCall)
198  return hash_combine(
199  MLOC.IsCall,
201 
202  hash_code hash =
204  MLOC.getCall()->getCalledValue()));
205 
206  for (const Value *Arg : MLOC.getCall()->args())
208  return hash;
209  }
210 
211  static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) {
212  return LHS == RHS;
213  }
214 };
215 
216 } // end namespace llvm
217 
218 /// This does one-way checks to see if Use could theoretically be hoisted above
219 /// MayClobber. This will not check the other way around.
220 ///
221 /// This assumes that, for the purposes of MemorySSA, Use comes directly after
222 /// MayClobber, with no potentially clobbering operations in between them.
223 /// (Where potentially clobbering ops are memory barriers, aliased stores, etc.)
224 static bool areLoadsReorderable(const LoadInst *Use,
225  const LoadInst *MayClobber) {
226  bool VolatileUse = Use->isVolatile();
227  bool VolatileClobber = MayClobber->isVolatile();
228  // Volatile operations may never be reordered with other volatile operations.
229  if (VolatileUse && VolatileClobber)
230  return false;
231  // Otherwise, volatile doesn't matter here. From the language reference:
232  // 'optimizers may change the order of volatile operations relative to
233  // non-volatile operations.'"
234 
235  // If a load is seq_cst, it cannot be moved above other loads. If its ordering
236  // is weaker, it can be moved above other loads. We just need to be sure that
237  // MayClobber isn't an acquire load, because loads can't be moved above
238  // acquire loads.
239  //
240  // Note that this explicitly *does* allow the free reordering of monotonic (or
241  // weaker) loads of the same address.
242  bool SeqCstUse = Use->getOrdering() == AtomicOrdering::SequentiallyConsistent;
243  bool MayClobberIsAcquire = isAtLeastOrStrongerThan(MayClobber->getOrdering(),
245  return !(SeqCstUse || MayClobberIsAcquire);
246 }
247 
248 namespace {
249 
250 struct ClobberAlias {
251  bool IsClobber;
253 };
254 
255 } // end anonymous namespace
256 
257 // Return a pair of {IsClobber (bool), AR (AliasResult)}. It relies on AR being
258 // ignored if IsClobber = false.
259 template <typename AliasAnalysisType>
260 static ClobberAlias
262  const Instruction *UseInst, AliasAnalysisType &AA) {
263  Instruction *DefInst = MD->getMemoryInst();
264  assert(DefInst && "Defining instruction not actually an instruction");
265  const auto *UseCall = dyn_cast<CallBase>(UseInst);
267 
268  if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(DefInst)) {
269  // These intrinsics will show up as affecting memory, but they are just
270  // markers, mostly.
271  //
272  // FIXME: We probably don't actually want MemorySSA to model these at all
273  // (including creating MemoryAccesses for them): we just end up inventing
274  // clobbers where they don't really exist at all. Please see D43269 for
275  // context.
276  switch (II->getIntrinsicID()) {
277  case Intrinsic::lifetime_start:
278  if (UseCall)
279  return {false, NoAlias};
280  AR = AA.alias(MemoryLocation(II->getArgOperand(1)), UseLoc);
281  return {AR != NoAlias, AR};
282  case Intrinsic::lifetime_end:
283  case Intrinsic::invariant_start:
284  case Intrinsic::invariant_end:
285  case Intrinsic::assume:
286  return {false, NoAlias};
287  default:
288  break;
289  }
290  }
291 
292  if (UseCall) {
293  ModRefInfo I = AA.getModRefInfo(DefInst, UseCall);
294  AR = isMustSet(I) ? MustAlias : MayAlias;
295  return {isModOrRefSet(I), AR};
296  }
297 
298  if (auto *DefLoad = dyn_cast<LoadInst>(DefInst))
299  if (auto *UseLoad = dyn_cast<LoadInst>(UseInst))
300  return {!areLoadsReorderable(UseLoad, DefLoad), MayAlias};
301 
302  ModRefInfo I = AA.getModRefInfo(DefInst, UseLoc);
303  AR = isMustSet(I) ? MustAlias : MayAlias;
304  return {isModSet(I), AR};
305 }
306 
307 template <typename AliasAnalysisType>
308 static ClobberAlias instructionClobbersQuery(MemoryDef *MD,
309  const MemoryUseOrDef *MU,
310  const MemoryLocOrCall &UseMLOC,
311  AliasAnalysisType &AA) {
312  // FIXME: This is a temporary hack to allow a single instructionClobbersQuery
313  // to exist while MemoryLocOrCall is pushed through places.
314  if (UseMLOC.IsCall)
316  AA);
317  return instructionClobbersQuery(MD, UseMLOC.getLoc(), MU->getMemoryInst(),
318  AA);
319 }
320 
321 // Return true when MD may alias MU, return false otherwise.
323  AliasAnalysis &AA) {
324  return instructionClobbersQuery(MD, MU, MemoryLocOrCall(MU), AA).IsClobber;
325 }
326 
327 namespace {
328 
329 struct UpwardsMemoryQuery {
330  // True if our original query started off as a call
331  bool IsCall = false;
332  // The pointer location we started the query with. This will be empty if
333  // IsCall is true.
334  MemoryLocation StartingLoc;
335  // This is the instruction we were querying about.
336  const Instruction *Inst = nullptr;
337  // The MemoryAccess we actually got called with, used to test local domination
338  const MemoryAccess *OriginalAccess = nullptr;
340  bool SkipSelfAccess = false;
341 
342  UpwardsMemoryQuery() = default;
343 
344  UpwardsMemoryQuery(const Instruction *Inst, const MemoryAccess *Access)
345  : IsCall(isa<CallBase>(Inst)), Inst(Inst), OriginalAccess(Access) {
346  if (!IsCall)
347  StartingLoc = MemoryLocation::get(Inst);
348  }
349 };
350 
351 } // end anonymous namespace
352 
353 static bool lifetimeEndsAt(MemoryDef *MD, const MemoryLocation &Loc,
354  BatchAAResults &AA) {
355  Instruction *Inst = MD->getMemoryInst();
356  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
357  switch (II->getIntrinsicID()) {
358  case Intrinsic::lifetime_end:
359  return AA.alias(MemoryLocation(II->getArgOperand(1)), Loc) == MustAlias;
360  default:
361  return false;
362  }
363  }
364  return false;
365 }
366 
367 template <typename AliasAnalysisType>
368 static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysisType &AA,
369  const Instruction *I) {
370  // If the memory can't be changed, then loads of the memory can't be
371  // clobbered.
372  return isa<LoadInst>(I) && (I->getMetadata(LLVMContext::MD_invariant_load) ||
373  AA.pointsToConstantMemory(MemoryLocation(
374  cast<LoadInst>(I)->getPointerOperand())));
375 }
376 
377 /// Verifies that `Start` is clobbered by `ClobberAt`, and that nothing
378 /// inbetween `Start` and `ClobberAt` can clobbers `Start`.
379 ///
380 /// This is meant to be as simple and self-contained as possible. Because it
381 /// uses no cache, etc., it can be relatively expensive.
382 ///
383 /// \param Start The MemoryAccess that we want to walk from.
384 /// \param ClobberAt A clobber for Start.
385 /// \param StartLoc The MemoryLocation for Start.
386 /// \param MSSA The MemorySSA instance that Start and ClobberAt belong to.
387 /// \param Query The UpwardsMemoryQuery we used for our search.
388 /// \param AA The AliasAnalysis we used for our search.
389 /// \param AllowImpreciseClobber Always false, unless we do relaxed verify.
390 
391 template <typename AliasAnalysisType>
392 LLVM_ATTRIBUTE_UNUSED static void
394  const MemoryLocation &StartLoc, const MemorySSA &MSSA,
395  const UpwardsMemoryQuery &Query, AliasAnalysisType &AA,
396  bool AllowImpreciseClobber = false) {
397  assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?");
398 
399  if (MSSA.isLiveOnEntryDef(Start)) {
400  assert(MSSA.isLiveOnEntryDef(ClobberAt) &&
401  "liveOnEntry must clobber itself");
402  return;
403  }
404 
405  bool FoundClobber = false;
408  Worklist.emplace_back(Start, StartLoc);
409  // Walk all paths from Start to ClobberAt, while looking for clobbers. If one
410  // is found, complain.
411  while (!Worklist.empty()) {
412  auto MAP = Worklist.pop_back_val();
413  // All we care about is that nothing from Start to ClobberAt clobbers Start.
414  // We learn nothing from revisiting nodes.
415  if (!VisitedPhis.insert(MAP).second)
416  continue;
417 
418  for (const auto *MA : def_chain(MAP.first)) {
419  if (MA == ClobberAt) {
420  if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
421  // instructionClobbersQuery isn't essentially free, so don't use `|=`,
422  // since it won't let us short-circuit.
423  //
424  // Also, note that this can't be hoisted out of the `Worklist` loop,
425  // since MD may only act as a clobber for 1 of N MemoryLocations.
426  FoundClobber = FoundClobber || MSSA.isLiveOnEntryDef(MD);
427  if (!FoundClobber) {
428  ClobberAlias CA =
429  instructionClobbersQuery(MD, MAP.second, Query.Inst, AA);
430  if (CA.IsClobber) {
431  FoundClobber = true;
432  // Not used: CA.AR;
433  }
434  }
435  }
436  break;
437  }
438 
439  // We should never hit liveOnEntry, unless it's the clobber.
440  assert(!MSSA.isLiveOnEntryDef(MA) && "Hit liveOnEntry before clobber?");
441 
442  if (const auto *MD = dyn_cast<MemoryDef>(MA)) {
443  // If Start is a Def, skip self.
444  if (MD == Start)
445  continue;
446 
447  assert(!instructionClobbersQuery(MD, MAP.second, Query.Inst, AA)
448  .IsClobber &&
449  "Found clobber before reaching ClobberAt!");
450  continue;
451  }
452 
453  if (const auto *MU = dyn_cast<MemoryUse>(MA)) {
454  (void)MU;
455  assert (MU == Start &&
456  "Can only find use in def chain if Start is a use");
457  continue;
458  }
459 
460  assert(isa<MemoryPhi>(MA));
461  Worklist.append(
462  upward_defs_begin({const_cast<MemoryAccess *>(MA), MAP.second}),
463  upward_defs_end());
464  }
465  }
466 
467  // If the verify is done following an optimization, it's possible that
468  // ClobberAt was a conservative clobbering, that we can now infer is not a
469  // true clobbering access. Don't fail the verify if that's the case.
470  // We do have accesses that claim they're optimized, but could be optimized
471  // further. Updating all these can be expensive, so allow it for now (FIXME).
472  if (AllowImpreciseClobber)
473  return;
474 
475  // If ClobberAt is a MemoryPhi, we can assume something above it acted as a
476  // clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point.
477  assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&
478  "ClobberAt never acted as a clobber");
479 }
480 
481 namespace {
482 
483 /// Our algorithm for walking (and trying to optimize) clobbers, all wrapped up
484 /// in one class.
485 template <class AliasAnalysisType> class ClobberWalker {
486  /// Save a few bytes by using unsigned instead of size_t.
487  using ListIndex = unsigned;
488 
489  /// Represents a span of contiguous MemoryDefs, potentially ending in a
490  /// MemoryPhi.
491  struct DefPath {
492  MemoryLocation Loc;
493  // Note that, because we always walk in reverse, Last will always dominate
494  // First. Also note that First and Last are inclusive.
495  MemoryAccess *First;
496  MemoryAccess *Last;
497  Optional<ListIndex> Previous;
498 
499  DefPath(const MemoryLocation &Loc, MemoryAccess *First, MemoryAccess *Last,
500  Optional<ListIndex> Previous)
501  : Loc(Loc), First(First), Last(Last), Previous(Previous) {}
502 
503  DefPath(const MemoryLocation &Loc, MemoryAccess *Init,
504  Optional<ListIndex> Previous)
505  : DefPath(Loc, Init, Init, Previous) {}
506  };
507 
508  const MemorySSA &MSSA;
509  AliasAnalysisType &AA;
510  DominatorTree &DT;
511  UpwardsMemoryQuery *Query;
512  unsigned *UpwardWalkLimit;
513 
514  // Phi optimization bookkeeping
517 
518  /// Find the nearest def or phi that `From` can legally be optimized to.
519  const MemoryAccess *getWalkTarget(const MemoryPhi *From) const {
520  assert(From->getNumOperands() && "Phi with no operands?");
521 
522  BasicBlock *BB = From->getBlock();
523  MemoryAccess *Result = MSSA.getLiveOnEntryDef();
524  DomTreeNode *Node = DT.getNode(BB);
525  while ((Node = Node->getIDom())) {
526  auto *Defs = MSSA.getBlockDefs(Node->getBlock());
527  if (Defs)
528  return &*Defs->rbegin();
529  }
530  return Result;
531  }
532 
533  /// Result of calling walkToPhiOrClobber.
534  struct UpwardsWalkResult {
535  /// The "Result" of the walk. Either a clobber, the last thing we walked, or
536  /// both. Include alias info when clobber found.
537  MemoryAccess *Result;
538  bool IsKnownClobber;
540  };
541 
542  /// Walk to the next Phi or Clobber in the def chain starting at Desc.Last.
543  /// This will update Desc.Last as it walks. It will (optionally) also stop at
544  /// StopAt.
545  ///
546  /// This does not test for whether StopAt is a clobber
547  UpwardsWalkResult
548  walkToPhiOrClobber(DefPath &Desc, const MemoryAccess *StopAt = nullptr,
549  const MemoryAccess *SkipStopAt = nullptr) const {
550  assert(!isa<MemoryUse>(Desc.Last) && "Uses don't exist in my world");
551  assert(UpwardWalkLimit && "Need a valid walk limit");
552  bool LimitAlreadyReached = false;
553  // (*UpwardWalkLimit) may be 0 here, due to the loop in tryOptimizePhi. Set
554  // it to 1. This will not do any alias() calls. It either returns in the
555  // first iteration in the loop below, or is set back to 0 if all def chains
556  // are free of MemoryDefs.
557  if (!*UpwardWalkLimit) {
558  *UpwardWalkLimit = 1;
559  LimitAlreadyReached = true;
560  }
561 
562  for (MemoryAccess *Current : def_chain(Desc.Last)) {
563  Desc.Last = Current;
564  if (Current == StopAt || Current == SkipStopAt)
565  return {Current, false, MayAlias};
566 
567  if (auto *MD = dyn_cast<MemoryDef>(Current)) {
568  if (MSSA.isLiveOnEntryDef(MD))
569  return {MD, true, MustAlias};
570 
571  if (!--*UpwardWalkLimit)
572  return {Current, true, MayAlias};
573 
574  ClobberAlias CA =
575  instructionClobbersQuery(MD, Desc.Loc, Query->Inst, AA);
576  if (CA.IsClobber)
577  return {MD, true, CA.AR};
578  }
579  }
580 
581  if (LimitAlreadyReached)
582  *UpwardWalkLimit = 0;
583 
584  assert(isa<MemoryPhi>(Desc.Last) &&
585  "Ended at a non-clobber that's not a phi?");
586  return {Desc.Last, false, MayAlias};
587  }
588 
589  void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches,
590  ListIndex PriorNode) {
591  auto UpwardDefs = make_range(upward_defs_begin({Phi, Paths[PriorNode].Loc}),
592  upward_defs_end());
593  for (const MemoryAccessPair &P : UpwardDefs) {
594  PausedSearches.push_back(Paths.size());
595  Paths.emplace_back(P.second, P.first, PriorNode);
596  }
597  }
598 
599  /// Represents a search that terminated after finding a clobber. This clobber
600  /// may or may not be present in the path of defs from LastNode..SearchStart,
601  /// since it may have been retrieved from cache.
602  struct TerminatedPath {
603  MemoryAccess *Clobber;
604  ListIndex LastNode;
605  };
606 
607  /// Get an access that keeps us from optimizing to the given phi.
608  ///
609  /// PausedSearches is an array of indices into the Paths array. Its incoming
610  /// value is the indices of searches that stopped at the last phi optimization
611  /// target. It's left in an unspecified state.
612  ///
613  /// If this returns None, NewPaused is a vector of searches that terminated
614  /// at StopWhere. Otherwise, NewPaused is left in an unspecified state.
616  getBlockingAccess(const MemoryAccess *StopWhere,
617  SmallVectorImpl<ListIndex> &PausedSearches,
618  SmallVectorImpl<ListIndex> &NewPaused,
619  SmallVectorImpl<TerminatedPath> &Terminated) {
620  assert(!PausedSearches.empty() && "No searches to continue?");
621 
622  // BFS vs DFS really doesn't make a difference here, so just do a DFS with
623  // PausedSearches as our stack.
624  while (!PausedSearches.empty()) {
625  ListIndex PathIndex = PausedSearches.pop_back_val();
626  DefPath &Node = Paths[PathIndex];
627 
628  // If we've already visited this path with this MemoryLocation, we don't
629  // need to do so again.
630  //
631  // NOTE: That we just drop these paths on the ground makes caching
632  // behavior sporadic. e.g. given a diamond:
633  // A
634  // B C
635  // D
636  //
637  // ...If we walk D, B, A, C, we'll only cache the result of phi
638  // optimization for A, B, and D; C will be skipped because it dies here.
639  // This arguably isn't the worst thing ever, since:
640  // - We generally query things in a top-down order, so if we got below D
641  // without needing cache entries for {C, MemLoc}, then chances are
642  // that those cache entries would end up ultimately unused.
643  // - We still cache things for A, so C only needs to walk up a bit.
644  // If this behavior becomes problematic, we can fix without a ton of extra
645  // work.
646  if (!VisitedPhis.insert({Node.Last, Node.Loc}).second)
647  continue;
648 
649  const MemoryAccess *SkipStopWhere = nullptr;
650  if (Query->SkipSelfAccess && Node.Loc == Query->StartingLoc) {
651  assert(isa<MemoryDef>(Query->OriginalAccess));
652  SkipStopWhere = Query->OriginalAccess;
653  }
654 
655  UpwardsWalkResult Res = walkToPhiOrClobber(Node,
656  /*StopAt=*/StopWhere,
657  /*SkipStopAt=*/SkipStopWhere);
658  if (Res.IsKnownClobber) {
659  assert(Res.Result != StopWhere && Res.Result != SkipStopWhere);
660 
661  // If this wasn't a cache hit, we hit a clobber when walking. That's a
662  // failure.
663  TerminatedPath Term{Res.Result, PathIndex};
664  if (!MSSA.dominates(Res.Result, StopWhere))
665  return Term;
666 
667  // Otherwise, it's a valid thing to potentially optimize to.
668  Terminated.push_back(Term);
669  continue;
670  }
671 
672  if (Res.Result == StopWhere || Res.Result == SkipStopWhere) {
673  // We've hit our target. Save this path off for if we want to continue
674  // walking. If we are in the mode of skipping the OriginalAccess, and
675  // we've reached back to the OriginalAccess, do not save path, we've
676  // just looped back to self.
677  if (Res.Result != SkipStopWhere)
678  NewPaused.push_back(PathIndex);
679  continue;
680  }
681 
682  assert(!MSSA.isLiveOnEntryDef(Res.Result) && "liveOnEntry is a clobber");
683  addSearches(cast<MemoryPhi>(Res.Result), PausedSearches, PathIndex);
684  }
685 
686  return None;
687  }
688 
689  template <typename T, typename Walker>
690  struct generic_def_path_iterator
691  : public iterator_facade_base<generic_def_path_iterator<T, Walker>,
692  std::forward_iterator_tag, T *> {
693  generic_def_path_iterator() {}
694  generic_def_path_iterator(Walker *W, ListIndex N) : W(W), N(N) {}
695 
696  T &operator*() const { return curNode(); }
697 
698  generic_def_path_iterator &operator++() {
699  N = curNode().Previous;
700  return *this;
701  }
702 
703  bool operator==(const generic_def_path_iterator &O) const {
704  if (N.hasValue() != O.N.hasValue())
705  return false;
706  return !N.hasValue() || *N == *O.N;
707  }
708 
709  private:
710  T &curNode() const { return W->Paths[*N]; }
711 
712  Walker *W = nullptr;
714  };
715 
716  using def_path_iterator = generic_def_path_iterator<DefPath, ClobberWalker>;
717  using const_def_path_iterator =
718  generic_def_path_iterator<const DefPath, const ClobberWalker>;
719 
720  iterator_range<def_path_iterator> def_path(ListIndex From) {
721  return make_range(def_path_iterator(this, From), def_path_iterator());
722  }
723 
724  iterator_range<const_def_path_iterator> const_def_path(ListIndex From) const {
725  return make_range(const_def_path_iterator(this, From),
726  const_def_path_iterator());
727  }
728 
729  struct OptznResult {
730  /// The path that contains our result.
731  TerminatedPath PrimaryClobber;
732  /// The paths that we can legally cache back from, but that aren't
733  /// necessarily the result of the Phi optimization.
734  SmallVector<TerminatedPath, 4> OtherClobbers;
735  };
736 
737  ListIndex defPathIndex(const DefPath &N) const {
738  // The assert looks nicer if we don't need to do &N
739  const DefPath *NP = &N;
740  assert(!Paths.empty() && NP >= &Paths.front() && NP <= &Paths.back() &&
741  "Out of bounds DefPath!");
742  return NP - &Paths.front();
743  }
744 
745  /// Try to optimize a phi as best as we can. Returns a SmallVector of Paths
746  /// that act as legal clobbers. Note that this won't return *all* clobbers.
747  ///
748  /// Phi optimization algorithm tl;dr:
749  /// - Find the earliest def/phi, A, we can optimize to
750  /// - Find if all paths from the starting memory access ultimately reach A
751  /// - If not, optimization isn't possible.
752  /// - Otherwise, walk from A to another clobber or phi, A'.
753  /// - If A' is a def, we're done.
754  /// - If A' is a phi, try to optimize it.
755  ///
756  /// A path is a series of {MemoryAccess, MemoryLocation} pairs. A path
757  /// terminates when a MemoryAccess that clobbers said MemoryLocation is found.
758  OptznResult tryOptimizePhi(MemoryPhi *Phi, MemoryAccess *Start,
759  const MemoryLocation &Loc) {
760  assert(Paths.empty() && VisitedPhis.empty() &&
761  "Reset the optimization state.");
762 
763  Paths.emplace_back(Loc, Start, Phi, None);
764  // Stores how many "valid" optimization nodes we had prior to calling
765  // addSearches/getBlockingAccess. Necessary for caching if we had a blocker.
766  auto PriorPathsSize = Paths.size();
767 
768  SmallVector<ListIndex, 16> PausedSearches;
769  SmallVector<ListIndex, 8> NewPaused;
770  SmallVector<TerminatedPath, 4> TerminatedPaths;
771 
772  addSearches(Phi, PausedSearches, 0);
773 
774  // Moves the TerminatedPath with the "most dominated" Clobber to the end of
775  // Paths.
776  auto MoveDominatedPathToEnd = [&](SmallVectorImpl<TerminatedPath> &Paths) {
777  assert(!Paths.empty() && "Need a path to move");
778  auto Dom = Paths.begin();
779  for (auto I = std::next(Dom), E = Paths.end(); I != E; ++I)
780  if (!MSSA.dominates(I->Clobber, Dom->Clobber))
781  Dom = I;
782  auto Last = Paths.end() - 1;
783  if (Last != Dom)
784  std::iter_swap(Last, Dom);
785  };
786 
787  MemoryPhi *Current = Phi;
788  while (true) {
789  assert(!MSSA.isLiveOnEntryDef(Current) &&
790  "liveOnEntry wasn't treated as a clobber?");
791 
792  const auto *Target = getWalkTarget(Current);
793  // If a TerminatedPath doesn't dominate Target, then it wasn't a legal
794  // optimization for the prior phi.
795  assert(all_of(TerminatedPaths, [&](const TerminatedPath &P) {
796  return MSSA.dominates(P.Clobber, Target);
797  }));
798 
799  // FIXME: This is broken, because the Blocker may be reported to be
800  // liveOnEntry, and we'll happily wait for that to disappear (read: never)
801  // For the moment, this is fine, since we do nothing with blocker info.
802  if (Optional<TerminatedPath> Blocker = getBlockingAccess(
803  Target, PausedSearches, NewPaused, TerminatedPaths)) {
804 
805  // Find the node we started at. We can't search based on N->Last, since
806  // we may have gone around a loop with a different MemoryLocation.
807  auto Iter = find_if(def_path(Blocker->LastNode), [&](const DefPath &N) {
808  return defPathIndex(N) < PriorPathsSize;
809  });
810  assert(Iter != def_path_iterator());
811 
812  DefPath &CurNode = *Iter;
813  assert(CurNode.Last == Current);
814 
815  // Two things:
816  // A. We can't reliably cache all of NewPaused back. Consider a case
817  // where we have two paths in NewPaused; one of which can't optimize
818  // above this phi, whereas the other can. If we cache the second path
819  // back, we'll end up with suboptimal cache entries. We can handle
820  // cases like this a bit better when we either try to find all
821  // clobbers that block phi optimization, or when our cache starts
822  // supporting unfinished searches.
823  // B. We can't reliably cache TerminatedPaths back here without doing
824  // extra checks; consider a case like:
825  // T
826  // / \
827  // D C
828  // \ /
829  // S
830  // Where T is our target, C is a node with a clobber on it, D is a
831  // diamond (with a clobber *only* on the left or right node, N), and
832  // S is our start. Say we walk to D, through the node opposite N
833  // (read: ignoring the clobber), and see a cache entry in the top
834  // node of D. That cache entry gets put into TerminatedPaths. We then
835  // walk up to C (N is later in our worklist), find the clobber, and
836  // quit. If we append TerminatedPaths to OtherClobbers, we'll cache
837  // the bottom part of D to the cached clobber, ignoring the clobber
838  // in N. Again, this problem goes away if we start tracking all
839  // blockers for a given phi optimization.
840  TerminatedPath Result{CurNode.Last, defPathIndex(CurNode)};
841  return {Result, {}};
842  }
843 
844  // If there's nothing left to search, then all paths led to valid clobbers
845  // that we got from our cache; pick the nearest to the start, and allow
846  // the rest to be cached back.
847  if (NewPaused.empty()) {
848  MoveDominatedPathToEnd(TerminatedPaths);
849  TerminatedPath Result = TerminatedPaths.pop_back_val();
850  return {Result, std::move(TerminatedPaths)};
851  }
852 
853  MemoryAccess *DefChainEnd = nullptr;
855  for (ListIndex Paused : NewPaused) {
856  UpwardsWalkResult WR = walkToPhiOrClobber(Paths[Paused]);
857  if (WR.IsKnownClobber)
858  Clobbers.push_back({WR.Result, Paused});
859  else
860  // Micro-opt: If we hit the end of the chain, save it.
861  DefChainEnd = WR.Result;
862  }
863 
864  if (!TerminatedPaths.empty()) {
865  // If we couldn't find the dominating phi/liveOnEntry in the above loop,
866  // do it now.
867  if (!DefChainEnd)
868  for (auto *MA : def_chain(const_cast<MemoryAccess *>(Target)))
869  DefChainEnd = MA;
870 
871  // If any of the terminated paths don't dominate the phi we'll try to
872  // optimize, we need to figure out what they are and quit.
873  const BasicBlock *ChainBB = DefChainEnd->getBlock();
874  for (const TerminatedPath &TP : TerminatedPaths) {
875  // Because we know that DefChainEnd is as "high" as we can go, we
876  // don't need local dominance checks; BB dominance is sufficient.
877  if (DT.dominates(ChainBB, TP.Clobber->getBlock()))
878  Clobbers.push_back(TP);
879  }
880  }
881 
882  // If we have clobbers in the def chain, find the one closest to Current
883  // and quit.
884  if (!Clobbers.empty()) {
885  MoveDominatedPathToEnd(Clobbers);
886  TerminatedPath Result = Clobbers.pop_back_val();
887  return {Result, std::move(Clobbers)};
888  }
889 
890  assert(all_of(NewPaused,
891  [&](ListIndex I) { return Paths[I].Last == DefChainEnd; }));
892 
893  // Because liveOnEntry is a clobber, this must be a phi.
894  auto *DefChainPhi = cast<MemoryPhi>(DefChainEnd);
895 
896  PriorPathsSize = Paths.size();
897  PausedSearches.clear();
898  for (ListIndex I : NewPaused)
899  addSearches(DefChainPhi, PausedSearches, I);
900  NewPaused.clear();
901 
902  Current = DefChainPhi;
903  }
904  }
905 
906  void verifyOptResult(const OptznResult &R) const {
907  assert(all_of(R.OtherClobbers, [&](const TerminatedPath &P) {
908  return MSSA.dominates(P.Clobber, R.PrimaryClobber.Clobber);
909  }));
910  }
911 
912  void resetPhiOptznState() {
913  Paths.clear();
914  VisitedPhis.clear();
915  }
916 
917 public:
918  ClobberWalker(const MemorySSA &MSSA, AliasAnalysisType &AA, DominatorTree &DT)
919  : MSSA(MSSA), AA(AA), DT(DT) {}
920 
921  AliasAnalysisType *getAA() { return &AA; }
922  /// Finds the nearest clobber for the given query, optimizing phis if
923  /// possible.
924  MemoryAccess *findClobber(MemoryAccess *Start, UpwardsMemoryQuery &Q,
925  unsigned &UpWalkLimit) {
926  Query = &Q;
927  UpwardWalkLimit = &UpWalkLimit;
928  // Starting limit must be > 0.
929  if (!UpWalkLimit)
930  UpWalkLimit++;
931 
932  MemoryAccess *Current = Start;
933  // This walker pretends uses don't exist. If we're handed one, silently grab
934  // its def. (This has the nice side-effect of ensuring we never cache uses)
935  if (auto *MU = dyn_cast<MemoryUse>(Start))
936  Current = MU->getDefiningAccess();
937 
938  DefPath FirstDesc(Q.StartingLoc, Current, Current, None);
939  // Fast path for the overly-common case (no crazy phi optimization
940  // necessary)
941  UpwardsWalkResult WalkResult = walkToPhiOrClobber(FirstDesc);
942  MemoryAccess *Result;
943  if (WalkResult.IsKnownClobber) {
944  Result = WalkResult.Result;
945  Q.AR = WalkResult.AR;
946  } else {
947  OptznResult OptRes = tryOptimizePhi(cast<MemoryPhi>(FirstDesc.Last),
948  Current, Q.StartingLoc);
949  verifyOptResult(OptRes);
950  resetPhiOptznState();
951  Result = OptRes.PrimaryClobber.Clobber;
952  }
953 
954 #ifdef EXPENSIVE_CHECKS
955  if (!Q.SkipSelfAccess && *UpwardWalkLimit > 0)
956  checkClobberSanity(Current, Result, Q.StartingLoc, MSSA, Q, AA);
957 #endif
958  return Result;
959  }
960 };
961 
962 struct RenamePassData {
963  DomTreeNode *DTN;
965  MemoryAccess *IncomingVal;
966 
967  RenamePassData(DomTreeNode *D, DomTreeNode::const_iterator It,
968  MemoryAccess *M)
969  : DTN(D), ChildIt(It), IncomingVal(M) {}
970 
971  void swap(RenamePassData &RHS) {
972  std::swap(DTN, RHS.DTN);
973  std::swap(ChildIt, RHS.ChildIt);
974  std::swap(IncomingVal, RHS.IncomingVal);
975  }
976 };
977 
978 } // end anonymous namespace
979 
980 namespace llvm {
981 
982 template <class AliasAnalysisType> class MemorySSA::ClobberWalkerBase {
983  ClobberWalker<AliasAnalysisType> Walker;
984  MemorySSA *MSSA;
985 
986 public:
987  ClobberWalkerBase(MemorySSA *M, AliasAnalysisType *A, DominatorTree *D)
988  : Walker(*M, *A, *D), MSSA(M) {}
989 
990  MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *,
991  const MemoryLocation &,
992  unsigned &);
993  // Third argument (bool), defines whether the clobber search should skip the
994  // original queried access. If true, there will be a follow-up query searching
995  // for a clobber access past "self". Note that the Optimized access is not
996  // updated if a new clobber is found by this SkipSelf search. If this
997  // additional query becomes heavily used we may decide to cache the result.
998  // Walker instantiations will decide how to set the SkipSelf bool.
999  MemoryAccess *getClobberingMemoryAccessBase(MemoryAccess *, unsigned &, bool);
1000 };
1001 
1002 /// A MemorySSAWalker that does AA walks to disambiguate accesses. It no
1003 /// longer does caching on its own, but the name has been retained for the
1004 /// moment.
1005 template <class AliasAnalysisType>
1006 class MemorySSA::CachingWalker final : public MemorySSAWalker {
1007  ClobberWalkerBase<AliasAnalysisType> *Walker;
1008 
1009 public:
1010  CachingWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
1011  : MemorySSAWalker(M), Walker(W) {}
1012  ~CachingWalker() override = default;
1013 
1015 
1016  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
1017  return Walker->getClobberingMemoryAccessBase(MA, UWL, false);
1018  }
1019  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1020  const MemoryLocation &Loc,
1021  unsigned &UWL) {
1022  return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
1023  }
1024 
1025  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
1026  unsigned UpwardWalkLimit = MaxCheckLimit;
1027  return getClobberingMemoryAccess(MA, UpwardWalkLimit);
1028  }
1029  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1030  const MemoryLocation &Loc) override {
1031  unsigned UpwardWalkLimit = MaxCheckLimit;
1032  return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
1033  }
1034 
1035  void invalidateInfo(MemoryAccess *MA) override {
1036  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1037  MUD->resetOptimized();
1038  }
1039 };
1040 
1041 template <class AliasAnalysisType>
1042 class MemorySSA::SkipSelfWalker final : public MemorySSAWalker {
1043  ClobberWalkerBase<AliasAnalysisType> *Walker;
1044 
1045 public:
1046  SkipSelfWalker(MemorySSA *M, ClobberWalkerBase<AliasAnalysisType> *W)
1047  : MemorySSAWalker(M), Walker(W) {}
1048  ~SkipSelfWalker() override = default;
1049 
1051 
1052  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA, unsigned &UWL) {
1053  return Walker->getClobberingMemoryAccessBase(MA, UWL, true);
1054  }
1055  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1056  const MemoryLocation &Loc,
1057  unsigned &UWL) {
1058  return Walker->getClobberingMemoryAccessBase(MA, Loc, UWL);
1059  }
1060 
1061  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA) override {
1062  unsigned UpwardWalkLimit = MaxCheckLimit;
1063  return getClobberingMemoryAccess(MA, UpwardWalkLimit);
1064  }
1065  MemoryAccess *getClobberingMemoryAccess(MemoryAccess *MA,
1066  const MemoryLocation &Loc) override {
1067  unsigned UpwardWalkLimit = MaxCheckLimit;
1068  return getClobberingMemoryAccess(MA, Loc, UpwardWalkLimit);
1069  }
1070 
1071  void invalidateInfo(MemoryAccess *MA) override {
1072  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1073  MUD->resetOptimized();
1074  }
1075 };
1076 
1077 } // end namespace llvm
1078 
1079 void MemorySSA::renameSuccessorPhis(BasicBlock *BB, MemoryAccess *IncomingVal,
1080  bool RenameAllUses) {
1081  // Pass through values to our successors
1082  for (const BasicBlock *S : successors(BB)) {
1083  auto It = PerBlockAccesses.find(S);
1084  // Rename the phi nodes in our successor block
1085  if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1086  continue;
1087  AccessList *Accesses = It->second.get();
1088  auto *Phi = cast<MemoryPhi>(&Accesses->front());
1089  if (RenameAllUses) {
1090  int PhiIndex = Phi->getBasicBlockIndex(BB);
1091  assert(PhiIndex != -1 && "Incomplete phi during partial rename");
1092  Phi->setIncomingValue(PhiIndex, IncomingVal);
1093  } else
1094  Phi->addIncoming(IncomingVal, BB);
1095  }
1096 }
1097 
1098 /// Rename a single basic block into MemorySSA form.
1099 /// Uses the standard SSA renaming algorithm.
1100 /// \returns The new incoming value.
1101 MemoryAccess *MemorySSA::renameBlock(BasicBlock *BB, MemoryAccess *IncomingVal,
1102  bool RenameAllUses) {
1103  auto It = PerBlockAccesses.find(BB);
1104  // Skip most processing if the list is empty.
1105  if (It != PerBlockAccesses.end()) {
1106  AccessList *Accesses = It->second.get();
1107  for (MemoryAccess &L : *Accesses) {
1108  if (MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&L)) {
1109  if (MUD->getDefiningAccess() == nullptr || RenameAllUses)
1110  MUD->setDefiningAccess(IncomingVal);
1111  if (isa<MemoryDef>(&L))
1112  IncomingVal = &L;
1113  } else {
1114  IncomingVal = &L;
1115  }
1116  }
1117  }
1118  return IncomingVal;
1119 }
1120 
1121 /// This is the standard SSA renaming algorithm.
1122 ///
1123 /// We walk the dominator tree in preorder, renaming accesses, and then filling
1124 /// in phi nodes in our successors.
1125 void MemorySSA::renamePass(DomTreeNode *Root, MemoryAccess *IncomingVal,
1127  bool SkipVisited, bool RenameAllUses) {
1128  assert(Root && "Trying to rename accesses in an unreachable block");
1129 
1131  // Skip everything if we already renamed this block and we are skipping.
1132  // Note: You can't sink this into the if, because we need it to occur
1133  // regardless of whether we skip blocks or not.
1134  bool AlreadyVisited = !Visited.insert(Root->getBlock()).second;
1135  if (SkipVisited && AlreadyVisited)
1136  return;
1137 
1138  IncomingVal = renameBlock(Root->getBlock(), IncomingVal, RenameAllUses);
1139  renameSuccessorPhis(Root->getBlock(), IncomingVal, RenameAllUses);
1140  WorkStack.push_back({Root, Root->begin(), IncomingVal});
1141 
1142  while (!WorkStack.empty()) {
1143  DomTreeNode *Node = WorkStack.back().DTN;
1144  DomTreeNode::const_iterator ChildIt = WorkStack.back().ChildIt;
1145  IncomingVal = WorkStack.back().IncomingVal;
1146 
1147  if (ChildIt == Node->end()) {
1148  WorkStack.pop_back();
1149  } else {
1150  DomTreeNode *Child = *ChildIt;
1151  ++WorkStack.back().ChildIt;
1152  BasicBlock *BB = Child->getBlock();
1153  // Note: You can't sink this into the if, because we need it to occur
1154  // regardless of whether we skip blocks or not.
1155  AlreadyVisited = !Visited.insert(BB).second;
1156  if (SkipVisited && AlreadyVisited) {
1157  // We already visited this during our renaming, which can happen when
1158  // being asked to rename multiple blocks. Figure out the incoming val,
1159  // which is the last def.
1160  // Incoming value can only change if there is a block def, and in that
1161  // case, it's the last block def in the list.
1162  if (auto *BlockDefs = getWritableBlockDefs(BB))
1163  IncomingVal = &*BlockDefs->rbegin();
1164  } else
1165  IncomingVal = renameBlock(BB, IncomingVal, RenameAllUses);
1166  renameSuccessorPhis(BB, IncomingVal, RenameAllUses);
1167  WorkStack.push_back({Child, Child->begin(), IncomingVal});
1168  }
1169  }
1170 }
1171 
1172 /// This handles unreachable block accesses by deleting phi nodes in
1173 /// unreachable blocks, and marking all other unreachable MemoryAccess's as
1174 /// being uses of the live on entry definition.
1175 void MemorySSA::markUnreachableAsLiveOnEntry(BasicBlock *BB) {
1176  assert(!DT->isReachableFromEntry(BB) &&
1177  "Reachable block found while handling unreachable blocks");
1178 
1179  // Make sure phi nodes in our reachable successors end up with a
1180  // LiveOnEntryDef for our incoming edge, even though our block is forward
1181  // unreachable. We could just disconnect these blocks from the CFG fully,
1182  // but we do not right now.
1183  for (const BasicBlock *S : successors(BB)) {
1184  if (!DT->isReachableFromEntry(S))
1185  continue;
1186  auto It = PerBlockAccesses.find(S);
1187  // Rename the phi nodes in our successor block
1188  if (It == PerBlockAccesses.end() || !isa<MemoryPhi>(It->second->front()))
1189  continue;
1190  AccessList *Accesses = It->second.get();
1191  auto *Phi = cast<MemoryPhi>(&Accesses->front());
1192  Phi->addIncoming(LiveOnEntryDef.get(), BB);
1193  }
1194 
1195  auto It = PerBlockAccesses.find(BB);
1196  if (It == PerBlockAccesses.end())
1197  return;
1198 
1199  auto &Accesses = It->second;
1200  for (auto AI = Accesses->begin(), AE = Accesses->end(); AI != AE;) {
1201  auto Next = std::next(AI);
1202  // If we have a phi, just remove it. We are going to replace all
1203  // users with live on entry.
1204  if (auto *UseOrDef = dyn_cast<MemoryUseOrDef>(AI))
1205  UseOrDef->setDefiningAccess(LiveOnEntryDef.get());
1206  else
1207  Accesses->erase(AI);
1208  AI = Next;
1209  }
1210 }
1211 
1213  : AA(nullptr), DT(DT), F(Func), LiveOnEntryDef(nullptr), Walker(nullptr),
1214  SkipWalker(nullptr), NextID(0) {
1215  // Build MemorySSA using a batch alias analysis. This reuses the internal
1216  // state that AA collects during an alias()/getModRefInfo() call. This is
1217  // safe because there are no CFG changes while building MemorySSA and can
1218  // significantly reduce the time spent by the compiler in AA, because we will
1219  // make queries about all the instructions in the Function.
1220  BatchAAResults BatchAA(*AA);
1221  buildMemorySSA(BatchAA);
1222  // Intentionally leave AA to nullptr while building so we don't accidently
1223  // use non-batch AliasAnalysis.
1224  this->AA = AA;
1225  // Also create the walker here.
1226  getWalker();
1227 }
1228 
1230  // Drop all our references
1231  for (const auto &Pair : PerBlockAccesses)
1232  for (MemoryAccess &MA : *Pair.second)
1233  MA.dropAllReferences();
1234 }
1235 
1236 MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) {
1237  auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr));
1238 
1239  if (Res.second)
1240  Res.first->second = llvm::make_unique<AccessList>();
1241  return Res.first->second.get();
1242 }
1243 
1244 MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) {
1245  auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr));
1246 
1247  if (Res.second)
1248  Res.first->second = llvm::make_unique<DefsList>();
1249  return Res.first->second.get();
1250 }
1251 
1252 namespace llvm {
1253 
1254 /// This class is a batch walker of all MemoryUse's in the program, and points
1255 /// their defining access at the thing that actually clobbers them. Because it
1256 /// is a batch walker that touches everything, it does not operate like the
1257 /// other walkers. This walker is basically performing a top-down SSA renaming
1258 /// pass, where the version stack is used as the cache. This enables it to be
1259 /// significantly more time and memory efficient than using the regular walker,
1260 /// which is walking bottom-up.
1262 public:
1263  OptimizeUses(MemorySSA *MSSA, CachingWalker<BatchAAResults> *Walker,
1264  BatchAAResults *BAA, DominatorTree *DT)
1265  : MSSA(MSSA), Walker(Walker), AA(BAA), DT(DT) {}
1266 
1267  void optimizeUses();
1268 
1269 private:
1270  /// This represents where a given memorylocation is in the stack.
1271  struct MemlocStackInfo {
1272  // This essentially is keeping track of versions of the stack. Whenever
1273  // the stack changes due to pushes or pops, these versions increase.
1274  unsigned long StackEpoch;
1275  unsigned long PopEpoch;
1276  // This is the lower bound of places on the stack to check. It is equal to
1277  // the place the last stack walk ended.
1278  // Note: Correctness depends on this being initialized to 0, which densemap
1279  // does
1280  unsigned long LowerBound;
1281  const BasicBlock *LowerBoundBlock;
1282  // This is where the last walk for this memory location ended.
1283  unsigned long LastKill;
1284  bool LastKillValid;
1286  };
1287 
1288  void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &,
1291 
1292  MemorySSA *MSSA;
1293  CachingWalker<BatchAAResults> *Walker;
1294  BatchAAResults *AA;
1295  DominatorTree *DT;
1296 };
1297 
1298 } // end namespace llvm
1299 
1300 /// Optimize the uses in a given block This is basically the SSA renaming
1301 /// algorithm, with one caveat: We are able to use a single stack for all
1302 /// MemoryUses. This is because the set of *possible* reaching MemoryDefs is
1303 /// the same for every MemoryUse. The *actual* clobbering MemoryDef is just
1304 /// going to be some position in that stack of possible ones.
1305 ///
1306 /// We track the stack positions that each MemoryLocation needs
1307 /// to check, and last ended at. This is because we only want to check the
1308 /// things that changed since last time. The same MemoryLocation should
1309 /// get clobbered by the same store (getModRefInfo does not use invariantness or
1310 /// things like this, and if they start, we can modify MemoryLocOrCall to
1311 /// include relevant data)
1312 void MemorySSA::OptimizeUses::optimizeUsesInBlock(
1313  const BasicBlock *BB, unsigned long &StackEpoch, unsigned long &PopEpoch,
1314  SmallVectorImpl<MemoryAccess *> &VersionStack,
1316 
1317  /// If no accesses, nothing to do.
1318  MemorySSA::AccessList *Accesses = MSSA->getWritableBlockAccesses(BB);
1319  if (Accesses == nullptr)
1320  return;
1321 
1322  // Pop everything that doesn't dominate the current block off the stack,
1323  // increment the PopEpoch to account for this.
1324  while (true) {
1325  assert(
1326  !VersionStack.empty() &&
1327  "Version stack should have liveOnEntry sentinel dominating everything");
1328  BasicBlock *BackBlock = VersionStack.back()->getBlock();
1329  if (DT->dominates(BackBlock, BB))
1330  break;
1331  while (VersionStack.back()->getBlock() == BackBlock)
1332  VersionStack.pop_back();
1333  ++PopEpoch;
1334  }
1335 
1336  for (MemoryAccess &MA : *Accesses) {
1337  auto *MU = dyn_cast<MemoryUse>(&MA);
1338  if (!MU) {
1339  VersionStack.push_back(&MA);
1340  ++StackEpoch;
1341  continue;
1342  }
1343 
1344  if (isUseTriviallyOptimizableToLiveOnEntry(*AA, MU->getMemoryInst())) {
1345  MU->setDefiningAccess(MSSA->getLiveOnEntryDef(), true, None);
1346  continue;
1347  }
1348 
1349  MemoryLocOrCall UseMLOC(MU);
1350  auto &LocInfo = LocStackInfo[UseMLOC];
1351  // If the pop epoch changed, it means we've removed stuff from top of
1352  // stack due to changing blocks. We may have to reset the lower bound or
1353  // last kill info.
1354  if (LocInfo.PopEpoch != PopEpoch) {
1355  LocInfo.PopEpoch = PopEpoch;
1356  LocInfo.StackEpoch = StackEpoch;
1357  // If the lower bound was in something that no longer dominates us, we
1358  // have to reset it.
1359  // We can't simply track stack size, because the stack may have had
1360  // pushes/pops in the meantime.
1361  // XXX: This is non-optimal, but only is slower cases with heavily
1362  // branching dominator trees. To get the optimal number of queries would
1363  // be to make lowerbound and lastkill a per-loc stack, and pop it until
1364  // the top of that stack dominates us. This does not seem worth it ATM.
1365  // A much cheaper optimization would be to always explore the deepest
1366  // branch of the dominator tree first. This will guarantee this resets on
1367  // the smallest set of blocks.
1368  if (LocInfo.LowerBoundBlock && LocInfo.LowerBoundBlock != BB &&
1369  !DT->dominates(LocInfo.LowerBoundBlock, BB)) {
1370  // Reset the lower bound of things to check.
1371  // TODO: Some day we should be able to reset to last kill, rather than
1372  // 0.
1373  LocInfo.LowerBound = 0;
1374  LocInfo.LowerBoundBlock = VersionStack[0]->getBlock();
1375  LocInfo.LastKillValid = false;
1376  }
1377  } else if (LocInfo.StackEpoch != StackEpoch) {
1378  // If all that has changed is the StackEpoch, we only have to check the
1379  // new things on the stack, because we've checked everything before. In
1380  // this case, the lower bound of things to check remains the same.
1381  LocInfo.PopEpoch = PopEpoch;
1382  LocInfo.StackEpoch = StackEpoch;
1383  }
1384  if (!LocInfo.LastKillValid) {
1385  LocInfo.LastKill = VersionStack.size() - 1;
1386  LocInfo.LastKillValid = true;
1387  LocInfo.AR = MayAlias;
1388  }
1389 
1390  // At this point, we should have corrected last kill and LowerBound to be
1391  // in bounds.
1392  assert(LocInfo.LowerBound < VersionStack.size() &&
1393  "Lower bound out of range");
1394  assert(LocInfo.LastKill < VersionStack.size() &&
1395  "Last kill info out of range");
1396  // In any case, the new upper bound is the top of the stack.
1397  unsigned long UpperBound = VersionStack.size() - 1;
1398 
1399  if (UpperBound - LocInfo.LowerBound > MaxCheckLimit) {
1400  LLVM_DEBUG(dbgs() << "MemorySSA skipping optimization of " << *MU << " ("
1401  << *(MU->getMemoryInst()) << ")"
1402  << " because there are "
1403  << UpperBound - LocInfo.LowerBound
1404  << " stores to disambiguate\n");
1405  // Because we did not walk, LastKill is no longer valid, as this may
1406  // have been a kill.
1407  LocInfo.LastKillValid = false;
1408  continue;
1409  }
1410  bool FoundClobberResult = false;
1411  unsigned UpwardWalkLimit = MaxCheckLimit;
1412  while (UpperBound > LocInfo.LowerBound) {
1413  if (isa<MemoryPhi>(VersionStack[UpperBound])) {
1414  // For phis, use the walker, see where we ended up, go there
1415  MemoryAccess *Result =
1416  Walker->getClobberingMemoryAccess(MU, UpwardWalkLimit);
1417  // We are guaranteed to find it or something is wrong
1418  while (VersionStack[UpperBound] != Result) {
1419  assert(UpperBound != 0);
1420  --UpperBound;
1421  }
1422  FoundClobberResult = true;
1423  break;
1424  }
1425 
1426  MemoryDef *MD = cast<MemoryDef>(VersionStack[UpperBound]);
1427  // If the lifetime of the pointer ends at this instruction, it's live on
1428  // entry.
1429  if (!UseMLOC.IsCall && lifetimeEndsAt(MD, UseMLOC.getLoc(), *AA)) {
1430  // Reset UpperBound to liveOnEntryDef's place in the stack
1431  UpperBound = 0;
1432  FoundClobberResult = true;
1433  LocInfo.AR = MustAlias;
1434  break;
1435  }
1436  ClobberAlias CA = instructionClobbersQuery(MD, MU, UseMLOC, *AA);
1437  if (CA.IsClobber) {
1438  FoundClobberResult = true;
1439  LocInfo.AR = CA.AR;
1440  break;
1441  }
1442  --UpperBound;
1443  }
1444 
1445  // Note: Phis always have AliasResult AR set to MayAlias ATM.
1446 
1447  // At the end of this loop, UpperBound is either a clobber, or lower bound
1448  // PHI walking may cause it to be < LowerBound, and in fact, < LastKill.
1449  if (FoundClobberResult || UpperBound < LocInfo.LastKill) {
1450  // We were last killed now by where we got to
1451  if (MSSA->isLiveOnEntryDef(VersionStack[UpperBound]))
1452  LocInfo.AR = None;
1453  MU->setDefiningAccess(VersionStack[UpperBound], true, LocInfo.AR);
1454  LocInfo.LastKill = UpperBound;
1455  } else {
1456  // Otherwise, we checked all the new ones, and now we know we can get to
1457  // LastKill.
1458  MU->setDefiningAccess(VersionStack[LocInfo.LastKill], true, LocInfo.AR);
1459  }
1460  LocInfo.LowerBound = VersionStack.size() - 1;
1461  LocInfo.LowerBoundBlock = BB;
1462  }
1463 }
1464 
1465 /// Optimize uses to point to their actual clobbering definitions.
1467  SmallVector<MemoryAccess *, 16> VersionStack;
1469  VersionStack.push_back(MSSA->getLiveOnEntryDef());
1470 
1471  unsigned long StackEpoch = 1;
1472  unsigned long PopEpoch = 1;
1473  // We perform a non-recursive top-down dominator tree walk.
1474  for (const auto *DomNode : depth_first(DT->getRootNode()))
1475  optimizeUsesInBlock(DomNode->getBlock(), StackEpoch, PopEpoch, VersionStack,
1476  LocStackInfo);
1477 }
1478 
1479 void MemorySSA::placePHINodes(
1480  const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks) {
1481  // Determine where our MemoryPhi's should go
1482  ForwardIDFCalculator IDFs(*DT);
1483  IDFs.setDefiningBlocks(DefiningBlocks);
1485  IDFs.calculate(IDFBlocks);
1486 
1487  // Now place MemoryPhi nodes.
1488  for (auto &BB : IDFBlocks)
1489  createMemoryPhi(BB);
1490 }
1491 
1492 void MemorySSA::buildMemorySSA(BatchAAResults &BAA) {
1493  // We create an access to represent "live on entry", for things like
1494  // arguments or users of globals, where the memory they use is defined before
1495  // the beginning of the function. We do not actually insert it into the IR.
1496  // We do not define a live on exit for the immediate uses, and thus our
1497  // semantics do *not* imply that something with no immediate uses can simply
1498  // be removed.
1499  BasicBlock &StartingPoint = F.getEntryBlock();
1500  LiveOnEntryDef.reset(new MemoryDef(F.getContext(), nullptr, nullptr,
1501  &StartingPoint, NextID++));
1502 
1503  // We maintain lists of memory accesses per-block, trading memory for time. We
1504  // could just look up the memory access for every possible instruction in the
1505  // stream.
1506  SmallPtrSet<BasicBlock *, 32> DefiningBlocks;
1507  // Go through each block, figure out where defs occur, and chain together all
1508  // the accesses.
1509  for (BasicBlock &B : F) {
1510  bool InsertIntoDef = false;
1511  AccessList *Accesses = nullptr;
1512  DefsList *Defs = nullptr;
1513  for (Instruction &I : B) {
1514  MemoryUseOrDef *MUD = createNewAccess(&I, &BAA);
1515  if (!MUD)
1516  continue;
1517 
1518  if (!Accesses)
1519  Accesses = getOrCreateAccessList(&B);
1520  Accesses->push_back(MUD);
1521  if (isa<MemoryDef>(MUD)) {
1522  InsertIntoDef = true;
1523  if (!Defs)
1524  Defs = getOrCreateDefsList(&B);
1525  Defs->push_back(*MUD);
1526  }
1527  }
1528  if (InsertIntoDef)
1529  DefiningBlocks.insert(&B);
1530  }
1531  placePHINodes(DefiningBlocks);
1532 
1533  // Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
1534  // filled in with all blocks.
1536  renamePass(DT->getRootNode(), LiveOnEntryDef.get(), Visited);
1537 
1538  ClobberWalkerBase<BatchAAResults> WalkerBase(this, &BAA, DT);
1539  CachingWalker<BatchAAResults> WalkerLocal(this, &WalkerBase);
1540  OptimizeUses(this, &WalkerLocal, &BAA, DT).optimizeUses();
1541 
1542  // Mark the uses in unreachable blocks as live on entry, so that they go
1543  // somewhere.
1544  for (auto &BB : F)
1545  if (!Visited.count(&BB))
1546  markUnreachableAsLiveOnEntry(&BB);
1547 }
1548 
1549 MemorySSAWalker *MemorySSA::getWalker() { return getWalkerImpl(); }
1550 
1551 MemorySSA::CachingWalker<AliasAnalysis> *MemorySSA::getWalkerImpl() {
1552  if (Walker)
1553  return Walker.get();
1554 
1555  if (!WalkerBase)
1556  WalkerBase =
1557  llvm::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);
1558 
1559  Walker =
1560  llvm::make_unique<CachingWalker<AliasAnalysis>>(this, WalkerBase.get());
1561  return Walker.get();
1562 }
1563 
1565  if (SkipWalker)
1566  return SkipWalker.get();
1567 
1568  if (!WalkerBase)
1569  WalkerBase =
1570  llvm::make_unique<ClobberWalkerBase<AliasAnalysis>>(this, AA, DT);
1571 
1572  SkipWalker =
1573  llvm::make_unique<SkipSelfWalker<AliasAnalysis>>(this, WalkerBase.get());
1574  return SkipWalker.get();
1575  }
1576 
1577 
1578 // This is a helper function used by the creation routines. It places NewAccess
1579 // into the access and defs lists for a given basic block, at the given
1580 // insertion point.
1582  const BasicBlock *BB,
1583  InsertionPlace Point) {
1584  auto *Accesses = getOrCreateAccessList(BB);
1585  if (Point == Beginning) {
1586  // If it's a phi node, it goes first, otherwise, it goes after any phi
1587  // nodes.
1588  if (isa<MemoryPhi>(NewAccess)) {
1589  Accesses->push_front(NewAccess);
1590  auto *Defs = getOrCreateDefsList(BB);
1591  Defs->push_front(*NewAccess);
1592  } else {
1593  auto AI = find_if_not(
1594  *Accesses, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1595  Accesses->insert(AI, NewAccess);
1596  if (!isa<MemoryUse>(NewAccess)) {
1597  auto *Defs = getOrCreateDefsList(BB);
1598  auto DI = find_if_not(
1599  *Defs, [](const MemoryAccess &MA) { return isa<MemoryPhi>(MA); });
1600  Defs->insert(DI, *NewAccess);
1601  }
1602  }
1603  } else {
1604  Accesses->push_back(NewAccess);
1605  if (!isa<MemoryUse>(NewAccess)) {
1606  auto *Defs = getOrCreateDefsList(BB);
1607  Defs->push_back(*NewAccess);
1608  }
1609  }
1610  BlockNumberingValid.erase(BB);
1611 }
1612 
1614  AccessList::iterator InsertPt) {
1615  auto *Accesses = getWritableBlockAccesses(BB);
1616  bool WasEnd = InsertPt == Accesses->end();
1617  Accesses->insert(AccessList::iterator(InsertPt), What);
1618  if (!isa<MemoryUse>(What)) {
1619  auto *Defs = getOrCreateDefsList(BB);
1620  // If we got asked to insert at the end, we have an easy job, just shove it
1621  // at the end. If we got asked to insert before an existing def, we also get
1622  // an iterator. If we got asked to insert before a use, we have to hunt for
1623  // the next def.
1624  if (WasEnd) {
1625  Defs->push_back(*What);
1626  } else if (isa<MemoryDef>(InsertPt)) {
1627  Defs->insert(InsertPt->getDefsIterator(), *What);
1628  } else {
1629  while (InsertPt != Accesses->end() && !isa<MemoryDef>(InsertPt))
1630  ++InsertPt;
1631  // Either we found a def, or we are inserting at the end
1632  if (InsertPt == Accesses->end())
1633  Defs->push_back(*What);
1634  else
1635  Defs->insert(InsertPt->getDefsIterator(), *What);
1636  }
1637  }
1638  BlockNumberingValid.erase(BB);
1639 }
1640 
1641 void MemorySSA::prepareForMoveTo(MemoryAccess *What, BasicBlock *BB) {
1642  // Keep it in the lookup tables, remove from the lists
1643  removeFromLists(What, false);
1644 
1645  // Note that moving should implicitly invalidate the optimized state of a
1646  // MemoryUse (and Phis can't be optimized). However, it doesn't do so for a
1647  // MemoryDef.
1648  if (auto *MD = dyn_cast<MemoryDef>(What))
1649  MD->resetOptimized();
1650  What->setBlock(BB);
1651 }
1652 
1653 // Move What before Where in the IR. The end result is that What will belong to
1654 // the right lists and have the right Block set, but will not otherwise be
1655 // correct. It will not have the right defining access, and if it is a def,
1656 // things below it will not properly be updated.
1658  AccessList::iterator Where) {
1659  prepareForMoveTo(What, BB);
1660  insertIntoListsBefore(What, BB, Where);
1661 }
1662 
1664  InsertionPlace Point) {
1665  if (isa<MemoryPhi>(What)) {
1666  assert(Point == Beginning &&
1667  "Can only move a Phi at the beginning of the block");
1668  // Update lookup table entry
1669  ValueToMemoryAccess.erase(What->getBlock());
1670  bool Inserted = ValueToMemoryAccess.insert({BB, What}).second;
1671  (void)Inserted;
1672  assert(Inserted && "Cannot move a Phi to a block that already has one");
1673  }
1674 
1675  prepareForMoveTo(What, BB);
1676  insertIntoListsForBlock(What, BB, Point);
1677 }
1678 
1679 MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) {
1680  assert(!getMemoryAccess(BB) && "MemoryPhi already exists for this BB");
1681  MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
1682  // Phi's always are placed at the front of the block.
1684  ValueToMemoryAccess[BB] = Phi;
1685  return Phi;
1686 }
1687 
1689  MemoryAccess *Definition,
1690  const MemoryUseOrDef *Template) {
1691  assert(!isa<PHINode>(I) && "Cannot create a defined access for a PHI");
1692  MemoryUseOrDef *NewAccess = createNewAccess(I, AA, Template);
1693  assert(
1694  NewAccess != nullptr &&
1695  "Tried to create a memory access for a non-memory touching instruction");
1696  NewAccess->setDefiningAccess(Definition);
1697  return NewAccess;
1698 }
1699 
1700 // Return true if the instruction has ordering constraints.
1701 // Note specifically that this only considers stores and loads
1702 // because others are still considered ModRef by getModRefInfo.
1703 static inline bool isOrdered(const Instruction *I) {
1704  if (auto *SI = dyn_cast<StoreInst>(I)) {
1705  if (!SI->isUnordered())
1706  return true;
1707  } else if (auto *LI = dyn_cast<LoadInst>(I)) {
1708  if (!LI->isUnordered())
1709  return true;
1710  }
1711  return false;
1712 }
1713 
1714 /// Helper function to create new memory accesses
1715 template <typename AliasAnalysisType>
1716 MemoryUseOrDef *MemorySSA::createNewAccess(Instruction *I,
1717  AliasAnalysisType *AAP,
1718  const MemoryUseOrDef *Template) {
1719  // The assume intrinsic has a control dependency which we model by claiming
1720  // that it writes arbitrarily. Ignore that fake memory dependency here.
1721  // FIXME: Replace this special casing with a more accurate modelling of
1722  // assume's control dependency.
1723  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
1724  if (II->getIntrinsicID() == Intrinsic::assume)
1725  return nullptr;
1726 
1727  bool Def, Use;
1728  if (Template) {
1729  Def = dyn_cast_or_null<MemoryDef>(Template) != nullptr;
1730  Use = dyn_cast_or_null<MemoryUse>(Template) != nullptr;
1731 #if !defined(NDEBUG)
1732  ModRefInfo ModRef = AAP->getModRefInfo(I, None);
1733  bool DefCheck, UseCheck;
1734  DefCheck = isModSet(ModRef) || isOrdered(I);
1735  UseCheck = isRefSet(ModRef);
1736  assert(Def == DefCheck && (Def || Use == UseCheck) && "Invalid template");
1737 #endif
1738  } else {
1739  // Find out what affect this instruction has on memory.
1740  ModRefInfo ModRef = AAP->getModRefInfo(I, None);
1741  // The isOrdered check is used to ensure that volatiles end up as defs
1742  // (atomics end up as ModRef right now anyway). Until we separate the
1743  // ordering chain from the memory chain, this enables people to see at least
1744  // some relative ordering to volatiles. Note that getClobberingMemoryAccess
1745  // will still give an answer that bypasses other volatile loads. TODO:
1746  // Separate memory aliasing and ordering into two different chains so that
1747  // we can precisely represent both "what memory will this read/write/is
1748  // clobbered by" and "what instructions can I move this past".
1749  Def = isModSet(ModRef) || isOrdered(I);
1750  Use = isRefSet(ModRef);
1751  }
1752 
1753  // It's possible for an instruction to not modify memory at all. During
1754  // construction, we ignore them.
1755  if (!Def && !Use)
1756  return nullptr;
1757 
1758  MemoryUseOrDef *MUD;
1759  if (Def)
1760  MUD = new MemoryDef(I->getContext(), nullptr, I, I->getParent(), NextID++);
1761  else
1762  MUD = new MemoryUse(I->getContext(), nullptr, I, I->getParent());
1763  ValueToMemoryAccess[I] = MUD;
1764  return MUD;
1765 }
1766 
1767 /// Returns true if \p Replacer dominates \p Replacee .
1768 bool MemorySSA::dominatesUse(const MemoryAccess *Replacer,
1769  const MemoryAccess *Replacee) const {
1770  if (isa<MemoryUseOrDef>(Replacee))
1771  return DT->dominates(Replacer->getBlock(), Replacee->getBlock());
1772  const auto *MP = cast<MemoryPhi>(Replacee);
1773  // For a phi node, the use occurs in the predecessor block of the phi node.
1774  // Since we may occur multiple times in the phi node, we have to check each
1775  // operand to ensure Replacer dominates each operand where Replacee occurs.
1776  for (const Use &Arg : MP->operands()) {
1777  if (Arg.get() != Replacee &&
1778  !DT->dominates(Replacer->getBlock(), MP->getIncomingBlock(Arg)))
1779  return false;
1780  }
1781  return true;
1782 }
1783 
1784 /// Properly remove \p MA from all of MemorySSA's lookup tables.
1786  assert(MA->use_empty() &&
1787  "Trying to remove memory access that still has uses");
1788  BlockNumbering.erase(MA);
1789  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1790  MUD->setDefiningAccess(nullptr);
1791  // Invalidate our walker's cache if necessary
1792  if (!isa<MemoryUse>(MA))
1793  getWalker()->invalidateInfo(MA);
1794 
1795  Value *MemoryInst;
1796  if (const auto *MUD = dyn_cast<MemoryUseOrDef>(MA))
1797  MemoryInst = MUD->getMemoryInst();
1798  else
1799  MemoryInst = MA->getBlock();
1800 
1801  auto VMA = ValueToMemoryAccess.find(MemoryInst);
1802  if (VMA->second == MA)
1803  ValueToMemoryAccess.erase(VMA);
1804 }
1805 
1806 /// Properly remove \p MA from all of MemorySSA's lists.
1807 ///
1808 /// Because of the way the intrusive list and use lists work, it is important to
1809 /// do removal in the right order.
1810 /// ShouldDelete defaults to true, and will cause the memory access to also be
1811 /// deleted, not just removed.
1812 void MemorySSA::removeFromLists(MemoryAccess *MA, bool ShouldDelete) {
1813  BasicBlock *BB = MA->getBlock();
1814  // The access list owns the reference, so we erase it from the non-owning list
1815  // first.
1816  if (!isa<MemoryUse>(MA)) {
1817  auto DefsIt = PerBlockDefs.find(BB);
1818  std::unique_ptr<DefsList> &Defs = DefsIt->second;
1819  Defs->remove(*MA);
1820  if (Defs->empty())
1821  PerBlockDefs.erase(DefsIt);
1822  }
1823 
1824  // The erase call here will delete it. If we don't want it deleted, we call
1825  // remove instead.
1826  auto AccessIt = PerBlockAccesses.find(BB);
1827  std::unique_ptr<AccessList> &Accesses = AccessIt->second;
1828  if (ShouldDelete)
1829  Accesses->erase(MA);
1830  else
1831  Accesses->remove(MA);
1832 
1833  if (Accesses->empty()) {
1834  PerBlockAccesses.erase(AccessIt);
1835  BlockNumberingValid.erase(BB);
1836  }
1837 }
1838 
1840  MemorySSAAnnotatedWriter Writer(this);
1841  F.print(OS, &Writer);
1842 }
1843 
1844 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1846 #endif
1847 
1849  verifyDefUses(F);
1851  verifyOrdering(F);
1853  // Previously, the verification used to also verify that the clobberingAccess
1854  // cached by MemorySSA is the same as the clobberingAccess found at a later
1855  // query to AA. This does not hold true in general due to the current fragility
1856  // of BasicAA which has arbitrary caps on the things it analyzes before giving
1857  // up. As a result, transformations that are correct, will lead to BasicAA
1858  // returning different Alias answers before and after that transformation.
1859  // Invalidating MemorySSA is not an option, as the results in BasicAA can be so
1860  // random, in the worst case we'd need to rebuild MemorySSA from scratch after
1861  // every transformation, which defeats the purpose of using it. For such an
1862  // example, see test4 added in D51960.
1863 }
1864 
1865 /// Verify that all of the blocks we believe to have valid domination numbers
1866 /// actually have valid domination numbers.
1868 #ifndef NDEBUG
1869  if (BlockNumberingValid.empty())
1870  return;
1871 
1872  SmallPtrSet<const BasicBlock *, 16> ValidBlocks = BlockNumberingValid;
1873  for (const BasicBlock &BB : F) {
1874  if (!ValidBlocks.count(&BB))
1875  continue;
1876 
1877  ValidBlocks.erase(&BB);
1878 
1879  const AccessList *Accesses = getBlockAccesses(&BB);
1880  // It's correct to say an empty block has valid numbering.
1881  if (!Accesses)
1882  continue;
1883 
1884  // Block numbering starts at 1.
1885  unsigned long LastNumber = 0;
1886  for (const MemoryAccess &MA : *Accesses) {
1887  auto ThisNumberIter = BlockNumbering.find(&MA);
1888  assert(ThisNumberIter != BlockNumbering.end() &&
1889  "MemoryAccess has no domination number in a valid block!");
1890 
1891  unsigned long ThisNumber = ThisNumberIter->second;
1892  assert(ThisNumber > LastNumber &&
1893  "Domination numbers should be strictly increasing!");
1894  LastNumber = ThisNumber;
1895  }
1896  }
1897 
1898  assert(ValidBlocks.empty() &&
1899  "All valid BasicBlocks should exist in F -- dangling pointers?");
1900 #endif
1901 }
1902 
1903 /// Verify that the order and existence of MemoryAccesses matches the
1904 /// order and existence of memory affecting instructions.
1906 #ifndef NDEBUG
1907  // Walk all the blocks, comparing what the lookups think and what the access
1908  // lists think, as well as the order in the blocks vs the order in the access
1909  // lists.
1910  SmallVector<MemoryAccess *, 32> ActualAccesses;
1912  for (BasicBlock &B : F) {
1913  const AccessList *AL = getBlockAccesses(&B);
1914  const auto *DL = getBlockDefs(&B);
1915  MemoryAccess *Phi = getMemoryAccess(&B);
1916  if (Phi) {
1917  ActualAccesses.push_back(Phi);
1918  ActualDefs.push_back(Phi);
1919  }
1920 
1921  for (Instruction &I : B) {
1922  MemoryAccess *MA = getMemoryAccess(&I);
1923  assert((!MA || (AL && (isa<MemoryUse>(MA) || DL))) &&
1924  "We have memory affecting instructions "
1925  "in this block but they are not in the "
1926  "access list or defs list");
1927  if (MA) {
1928  ActualAccesses.push_back(MA);
1929  if (isa<MemoryDef>(MA))
1930  ActualDefs.push_back(MA);
1931  }
1932  }
1933  // Either we hit the assert, really have no accesses, or we have both
1934  // accesses and an access list.
1935  // Same with defs.
1936  if (!AL && !DL)
1937  continue;
1938  assert(AL->size() == ActualAccesses.size() &&
1939  "We don't have the same number of accesses in the block as on the "
1940  "access list");
1941  assert((DL || ActualDefs.size() == 0) &&
1942  "Either we should have a defs list, or we should have no defs");
1943  assert((!DL || DL->size() == ActualDefs.size()) &&
1944  "We don't have the same number of defs in the block as on the "
1945  "def list");
1946  auto ALI = AL->begin();
1947  auto AAI = ActualAccesses.begin();
1948  while (ALI != AL->end() && AAI != ActualAccesses.end()) {
1949  assert(&*ALI == *AAI && "Not the same accesses in the same order");
1950  ++ALI;
1951  ++AAI;
1952  }
1953  ActualAccesses.clear();
1954  if (DL) {
1955  auto DLI = DL->begin();
1956  auto ADI = ActualDefs.begin();
1957  while (DLI != DL->end() && ADI != ActualDefs.end()) {
1958  assert(&*DLI == *ADI && "Not the same defs in the same order");
1959  ++DLI;
1960  ++ADI;
1961  }
1962  }
1963  ActualDefs.clear();
1964  }
1965 #endif
1966 }
1967 
1968 /// Verify the domination properties of MemorySSA by checking that each
1969 /// definition dominates all of its uses.
1971 #ifndef NDEBUG
1972  for (BasicBlock &B : F) {
1973  // Phi nodes are attached to basic blocks
1974  if (MemoryPhi *MP = getMemoryAccess(&B))
1975  for (const Use &U : MP->uses())
1976  assert(dominates(MP, U) && "Memory PHI does not dominate it's uses");
1977 
1978  for (Instruction &I : B) {
1979  MemoryAccess *MD = dyn_cast_or_null<MemoryDef>(getMemoryAccess(&I));
1980  if (!MD)
1981  continue;
1982 
1983  for (const Use &U : MD->uses())
1984  assert(dominates(MD, U) && "Memory Def does not dominate it's uses");
1985  }
1986  }
1987 #endif
1988 }
1989 
1990 /// Verify the def-use lists in MemorySSA, by verifying that \p Use
1991 /// appears in the use list of \p Def.
1992 void MemorySSA::verifyUseInDefs(MemoryAccess *Def, MemoryAccess *Use) const {
1993 #ifndef NDEBUG
1994  // The live on entry use may cause us to get a NULL def here
1995  if (!Def)
1996  assert(isLiveOnEntryDef(Use) &&
1997  "Null def but use not point to live on entry def");
1998  else
1999  assert(is_contained(Def->users(), Use) &&
2000  "Did not find use in def's use list");
2001 #endif
2002 }
2003 
2004 /// Verify the immediate use information, by walking all the memory
2005 /// accesses and verifying that, for each use, it appears in the
2006 /// appropriate def's use list
2008 #ifndef NDEBUG
2009  for (BasicBlock &B : F) {
2010  // Phi nodes are attached to basic blocks
2011  if (MemoryPhi *Phi = getMemoryAccess(&B)) {
2012  assert(Phi->getNumOperands() == static_cast<unsigned>(std::distance(
2013  pred_begin(&B), pred_end(&B))) &&
2014  "Incomplete MemoryPhi Node");
2015  for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
2016  verifyUseInDefs(Phi->getIncomingValue(I), Phi);
2017  assert(find(predecessors(&B), Phi->getIncomingBlock(I)) !=
2018  pred_end(&B) &&
2019  "Incoming phi block not a block predecessor");
2020  }
2021  }
2022 
2023  for (Instruction &I : B) {
2024  if (MemoryUseOrDef *MA = getMemoryAccess(&I)) {
2025  verifyUseInDefs(MA->getDefiningAccess(), MA);
2026  }
2027  }
2028  }
2029 #endif
2030 }
2031 
2032 /// Perform a local numbering on blocks so that instruction ordering can be
2033 /// determined in constant time.
2034 /// TODO: We currently just number in order. If we numbered by N, we could
2035 /// allow at least N-1 sequences of insertBefore or insertAfter (and at least
2036 /// log2(N) sequences of mixed before and after) without needing to invalidate
2037 /// the numbering.
2038 void MemorySSA::renumberBlock(const BasicBlock *B) const {
2039  // The pre-increment ensures the numbers really start at 1.
2040  unsigned long CurrentNumber = 0;
2041  const AccessList *AL = getBlockAccesses(B);
2042  assert(AL != nullptr && "Asking to renumber an empty block");
2043  for (const auto &I : *AL)
2044  BlockNumbering[&I] = ++CurrentNumber;
2045  BlockNumberingValid.insert(B);
2046 }
2047 
2048 /// Determine, for two memory accesses in the same block,
2049 /// whether \p Dominator dominates \p Dominatee.
2050 /// \returns True if \p Dominator dominates \p Dominatee.
2052  const MemoryAccess *Dominatee) const {
2053  const BasicBlock *DominatorBlock = Dominator->getBlock();
2054 
2055  assert((DominatorBlock == Dominatee->getBlock()) &&
2056  "Asking for local domination when accesses are in different blocks!");
2057  // A node dominates itself.
2058  if (Dominatee == Dominator)
2059  return true;
2060 
2061  // When Dominatee is defined on function entry, it is not dominated by another
2062  // memory access.
2063  if (isLiveOnEntryDef(Dominatee))
2064  return false;
2065 
2066  // When Dominator is defined on function entry, it dominates the other memory
2067  // access.
2068  if (isLiveOnEntryDef(Dominator))
2069  return true;
2070 
2071  if (!BlockNumberingValid.count(DominatorBlock))
2072  renumberBlock(DominatorBlock);
2073 
2074  unsigned long DominatorNum = BlockNumbering.lookup(Dominator);
2075  // All numbers start with 1
2076  assert(DominatorNum != 0 && "Block was not numbered properly");
2077  unsigned long DominateeNum = BlockNumbering.lookup(Dominatee);
2078  assert(DominateeNum != 0 && "Block was not numbered properly");
2079  return DominatorNum < DominateeNum;
2080 }
2081 
2082 bool MemorySSA::dominates(const MemoryAccess *Dominator,
2083  const MemoryAccess *Dominatee) const {
2084  if (Dominator == Dominatee)
2085  return true;
2086 
2087  if (isLiveOnEntryDef(Dominatee))
2088  return false;
2089 
2090  if (Dominator->getBlock() != Dominatee->getBlock())
2091  return DT->dominates(Dominator->getBlock(), Dominatee->getBlock());
2092  return locallyDominates(Dominator, Dominatee);
2093 }
2094 
2095 bool MemorySSA::dominates(const MemoryAccess *Dominator,
2096  const Use &Dominatee) const {
2097  if (MemoryPhi *MP = dyn_cast<MemoryPhi>(Dominatee.getUser())) {
2098  BasicBlock *UseBB = MP->getIncomingBlock(Dominatee);
2099  // The def must dominate the incoming block of the phi.
2100  if (UseBB != Dominator->getBlock())
2101  return DT->dominates(Dominator->getBlock(), UseBB);
2102  // If the UseBB and the DefBB are the same, compare locally.
2103  return locallyDominates(Dominator, cast<MemoryAccess>(Dominatee));
2104  }
2105  // If it's not a PHI node use, the normal dominates can already handle it.
2106  return dominates(Dominator, cast<MemoryAccess>(Dominatee.getUser()));
2107 }
2108 
2109 const static char LiveOnEntryStr[] = "liveOnEntry";
2110 
2112  switch (getValueID()) {
2113  case MemoryPhiVal: return static_cast<const MemoryPhi *>(this)->print(OS);
2114  case MemoryDefVal: return static_cast<const MemoryDef *>(this)->print(OS);
2115  case MemoryUseVal: return static_cast<const MemoryUse *>(this)->print(OS);
2116  }
2117  llvm_unreachable("invalid value id");
2118 }
2119 
2121  MemoryAccess *UO = getDefiningAccess();
2122 
2123  auto printID = [&OS](MemoryAccess *A) {
2124  if (A && A->getID())
2125  OS << A->getID();
2126  else
2127  OS << LiveOnEntryStr;
2128  };
2129 
2130  OS << getID() << " = MemoryDef(";
2131  printID(UO);
2132  OS << ")";
2133 
2134  if (isOptimized()) {
2135  OS << "->";
2136  printID(getOptimized());
2137 
2138  if (Optional<AliasResult> AR = getOptimizedAccessType())
2139  OS << " " << *AR;
2140  }
2141 }
2142 
2144  bool First = true;
2145  OS << getID() << " = MemoryPhi(";
2146  for (const auto &Op : operands()) {
2147  BasicBlock *BB = getIncomingBlock(Op);
2148  MemoryAccess *MA = cast<MemoryAccess>(Op);
2149  if (!First)
2150  OS << ',';
2151  else
2152  First = false;
2153 
2154  OS << '{';
2155  if (BB->hasName())
2156  OS << BB->getName();
2157  else
2158  BB->printAsOperand(OS, false);
2159  OS << ',';
2160  if (unsigned ID = MA->getID())
2161  OS << ID;
2162  else
2163  OS << LiveOnEntryStr;
2164  OS << '}';
2165  }
2166  OS << ')';
2167 }
2168 
2170  MemoryAccess *UO = getDefiningAccess();
2171  OS << "MemoryUse(";
2172  if (UO && UO->getID())
2173  OS << UO->getID();
2174  else
2175  OS << LiveOnEntryStr;
2176  OS << ')';
2177 
2178  if (Optional<AliasResult> AR = getOptimizedAccessType())
2179  OS << " " << *AR;
2180 }
2181 
2182 void MemoryAccess::dump() const {
2183 // Cannot completely remove virtual function even in release mode.
2184 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2185  print(dbgs());
2186  dbgs() << "\n";
2187 #endif
2188 }
2189 
2191 
2194 }
2195 
2197  AU.setPreservesAll();
2198  AU.addRequired<MemorySSAWrapperPass>();
2199 }
2200 
2202  auto &MSSA = getAnalysis<MemorySSAWrapperPass>().getMSSA();
2203  MSSA.print(dbgs());
2204  if (VerifyMemorySSA)
2205  MSSA.verifyMemorySSA();
2206  return false;
2207 }
2208 
2209 AnalysisKey MemorySSAAnalysis::Key;
2210 
2213  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
2214  auto &AA = AM.getResult<AAManager>(F);
2215  return MemorySSAAnalysis::Result(llvm::make_unique<MemorySSA>(F, &AA, &DT));
2216 }
2217 
2219  Function &F, const PreservedAnalyses &PA,
2221  auto PAC = PA.getChecker<MemorySSAAnalysis>();
2222  return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
2223  Inv.invalidate<AAManager>(F, PA) ||
2224  Inv.invalidate<DominatorTreeAnalysis>(F, PA);
2225 }
2226 
2229  OS << "MemorySSA for function: " << F.getName() << "\n";
2230  AM.getResult<MemorySSAAnalysis>(F).getMSSA().print(OS);
2231 
2232  return PreservedAnalyses::all();
2233 }
2234 
2237  AM.getResult<MemorySSAAnalysis>(F).getMSSA().verifyMemorySSA();
2238 
2239  return PreservedAnalyses::all();
2240 }
2241 
2242 char MemorySSAWrapperPass::ID = 0;
2243 
2246 }
2247 
2248 void MemorySSAWrapperPass::releaseMemory() { MSSA.reset(); }
2249 
2251  AU.setPreservesAll();
2254 }
2255 
2257  auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2258  auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
2259  MSSA.reset(new MemorySSA(F, &AA, &DT));
2260  return false;
2261 }
2262 
2263 void MemorySSAWrapperPass::verifyAnalysis() const { MSSA->verifyMemorySSA(); }
2264 
2266  MSSA->print(OS);
2267 }
2268 
2270 
2271 /// Walk the use-def chains starting at \p StartingAccess and find
2272 /// the MemoryAccess that actually clobbers Loc.
2273 ///
2274 /// \returns our clobbering memory access
2275 template <typename AliasAnalysisType>
2276 MemoryAccess *
2277 MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
2278  MemoryAccess *StartingAccess, const MemoryLocation &Loc,
2279  unsigned &UpwardWalkLimit) {
2280  if (isa<MemoryPhi>(StartingAccess))
2281  return StartingAccess;
2282 
2283  auto *StartingUseOrDef = cast<MemoryUseOrDef>(StartingAccess);
2284  if (MSSA->isLiveOnEntryDef(StartingUseOrDef))
2285  return StartingUseOrDef;
2286 
2287  Instruction *I = StartingUseOrDef->getMemoryInst();
2288 
2289  // Conservatively, fences are always clobbers, so don't perform the walk if we
2290  // hit a fence.
2291  if (!isa<CallBase>(I) && I->isFenceLike())
2292  return StartingUseOrDef;
2293 
2294  UpwardsMemoryQuery Q;
2295  Q.OriginalAccess = StartingUseOrDef;
2296  Q.StartingLoc = Loc;
2297  Q.Inst = I;
2298  Q.IsCall = false;
2299 
2300  // Unlike the other function, do not walk to the def of a def, because we are
2301  // handed something we already believe is the clobbering access.
2302  // We never set SkipSelf to true in Q in this method.
2303  MemoryAccess *DefiningAccess = isa<MemoryUse>(StartingUseOrDef)
2304  ? StartingUseOrDef->getDefiningAccess()
2305  : StartingUseOrDef;
2306 
2307  MemoryAccess *Clobber =
2308  Walker.findClobber(DefiningAccess, Q, UpwardWalkLimit);
2309  LLVM_DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ");
2310  LLVM_DEBUG(dbgs() << *StartingUseOrDef << "\n");
2311  LLVM_DEBUG(dbgs() << "Final Memory SSA clobber for " << *I << " is ");
2312  LLVM_DEBUG(dbgs() << *Clobber << "\n");
2313  return Clobber;
2314 }
2315 
2316 template <typename AliasAnalysisType>
2317 MemoryAccess *
2318 MemorySSA::ClobberWalkerBase<AliasAnalysisType>::getClobberingMemoryAccessBase(
2319  MemoryAccess *MA, unsigned &UpwardWalkLimit, bool SkipSelf) {
2320  auto *StartingAccess = dyn_cast<MemoryUseOrDef>(MA);
2321  // If this is a MemoryPhi, we can't do anything.
2322  if (!StartingAccess)
2323  return MA;
2324 
2325  bool IsOptimized = false;
2326 
2327  // If this is an already optimized use or def, return the optimized result.
2328  // Note: Currently, we store the optimized def result in a separate field,
2329  // since we can't use the defining access.
2330  if (StartingAccess->isOptimized()) {
2331  if (!SkipSelf || !isa<MemoryDef>(StartingAccess))
2332  return StartingAccess->getOptimized();
2333  IsOptimized = true;
2334  }
2335 
2336  const Instruction *I = StartingAccess->getMemoryInst();
2337  // We can't sanely do anything with a fence, since they conservatively clobber
2338  // all memory, and have no locations to get pointers from to try to
2339  // disambiguate.
2340  if (!isa<CallBase>(I) && I->isFenceLike())
2341  return StartingAccess;
2342 
2343  UpwardsMemoryQuery Q(I, StartingAccess);
2344 
2345  if (isUseTriviallyOptimizableToLiveOnEntry(*Walker.getAA(), I)) {
2346  MemoryAccess *LiveOnEntry = MSSA->getLiveOnEntryDef();
2347  StartingAccess->setOptimized(LiveOnEntry);
2348  StartingAccess->setOptimizedAccessType(None);
2349  return LiveOnEntry;
2350  }
2351 
2352  MemoryAccess *OptimizedAccess;
2353  if (!IsOptimized) {
2354  // Start with the thing we already think clobbers this location
2355  MemoryAccess *DefiningAccess = StartingAccess->getDefiningAccess();
2356 
2357  // At this point, DefiningAccess may be the live on entry def.
2358  // If it is, we will not get a better result.
2359  if (MSSA->isLiveOnEntryDef(DefiningAccess)) {
2360  StartingAccess->setOptimized(DefiningAccess);
2361  StartingAccess->setOptimizedAccessType(None);
2362  return DefiningAccess;
2363  }
2364 
2365  OptimizedAccess = Walker.findClobber(DefiningAccess, Q, UpwardWalkLimit);
2366  StartingAccess->setOptimized(OptimizedAccess);
2367  if (MSSA->isLiveOnEntryDef(OptimizedAccess))
2368  StartingAccess->setOptimizedAccessType(None);
2369  else if (Q.AR == MustAlias)
2370  StartingAccess->setOptimizedAccessType(MustAlias);
2371  } else
2372  OptimizedAccess = StartingAccess->getOptimized();
2373 
2374  LLVM_DEBUG(dbgs() << "Starting Memory SSA clobber for " << *I << " is ");
2375  LLVM_DEBUG(dbgs() << *StartingAccess << "\n");
2376  LLVM_DEBUG(dbgs() << "Optimized Memory SSA clobber for " << *I << " is ");
2377  LLVM_DEBUG(dbgs() << *OptimizedAccess << "\n");
2378 
2379  MemoryAccess *Result;
2380  if (SkipSelf && isa<MemoryPhi>(OptimizedAccess) &&
2381  isa<MemoryDef>(StartingAccess) && UpwardWalkLimit) {
2382  assert(isa<MemoryDef>(Q.OriginalAccess));
2383  Q.SkipSelfAccess = true;
2384  Result = Walker.findClobber(OptimizedAccess, Q, UpwardWalkLimit);
2385  } else
2386  Result = OptimizedAccess;
2387 
2388  LLVM_DEBUG(dbgs() << "Result Memory SSA clobber [SkipSelf = " << SkipSelf);
2389  LLVM_DEBUG(dbgs() << "] for " << *I << " is " << *Result << "\n");
2390 
2391  return Result;
2392 }
2393 
2394 MemoryAccess *
2396  if (auto *Use = dyn_cast<MemoryUseOrDef>(MA))
2397  return Use->getDefiningAccess();
2398  return MA;
2399 }
2400 
2402  MemoryAccess *StartingAccess, const MemoryLocation &) {
2403  if (auto *Use = dyn_cast<MemoryUseOrDef>(StartingAccess))
2404  return Use->getDefiningAccess();
2405  return StartingAccess;
2406 }
2407 
2408 void MemoryPhi::deleteMe(DerivedUser *Self) {
2409  delete static_cast<MemoryPhi *>(Self);
2410 }
2411 
2412 void MemoryDef::deleteMe(DerivedUser *Self) {
2413  delete static_cast<MemoryDef *>(Self);
2414 }
2415 
2416 void MemoryUse::deleteMe(DerivedUser *Self) {
2417  delete static_cast<MemoryUse *>(Self);
2418 }
MemorySSAWalker * getWalker()
Definition: MemorySSA.cpp:1549
bool runOnFunction(Function &) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass...
Definition: MemorySSA.cpp:2256
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:802
reference emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:641
typename std::vector< DomTreeNodeBase *>::const_iterator const_iterator
bool invalidate(IRUnitT &IR, const PreservedAnalyses &PA)
Trigger the invalidation of some other analysis pass if not already handled and return whether it was...
Definition: PassManager.h:666
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:551
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:776
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2143
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:2082
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:53
const AccessList * getBlockAccesses(const BasicBlock *BB) const
Return the list of MemoryAccess&#39;s for a given basic block.
Definition: MemorySSA.h:758
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:2196
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:375
AtomicOrdering getOrdering() const
Returns the ordering constraint of this load instruction.
Definition: Instructions.h:247
static const char LiveOnEntryStr[]
Definition: MemorySSA.cpp:2109
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:732
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:2250
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:1192
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1100
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:1272
This defines the Use class.
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2120
void calculate(SmallVectorImpl< NodeTy *> &IDFBlocks)
Calculate iterated dominance frontiers.
MemorySSA(Function &, AliasAnalysis *, DominatorTree *)
Definition: MemorySSA.cpp:1212
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
PreservedAnalysisChecker getChecker() const
Build a checker for this PreservedAnalyses and the specified analysis type.
Definition: PassManager.h:311
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:1263
std::pair< iterator, bool > insert(const std::pair< KeyT, ValueT > &KV)
Definition: DenseMap.h:221
Represents read-only accesses to memory.
Definition: MemorySSA.h:319
This class is a batch walker of all MemoryUse&#39;s in the program, and points their defining access at t...
Definition: MemorySSA.cpp:1261
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:50
Legacy analysis pass which computes MemorySSA.
Definition: MemorySSA.h:963
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:353
void renamePass(BasicBlock *BB, MemoryAccess *IncomingVal, SmallPtrSetImpl< BasicBlock *> &Visited)
Definition: MemorySSA.h:821
A Use represents the edge between a Value definition and its users.
Definition: Use.h:55
static bool defClobbersUseOrDef(MemoryDef *MD, const MemoryUseOrDef *MU, AliasAnalysis &AA)
Definition: MemorySSA.cpp:322
MemorySSAAnnotatedWriter(const MemorySSA *M)
Definition: MemorySSA.cpp:103
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:703
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:766
void insertIntoListsForBlock(MemoryAccess *, const BasicBlock *, InsertionPlace)
Definition: MemorySSA.cpp:1581
static bool isOrdered(const Instruction *I)
Definition: MemorySSA.cpp:1703
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:877
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:2007
void verifyAnalysis() const override
verifyAnalysis() - This member can be implemented by a analysis pass to check state of analysis infor...
Definition: MemorySSA.cpp:2263
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:720
upward_defs_iterator upward_defs_end()
Definition: MemorySSA.h:1246
early cse memssa
Definition: EarlyCSE.cpp:1423
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:105
void dump() const
Definition: MemorySSA.cpp:1845
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:994
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:97
void removeFromLookups(MemoryAccess *)
Properly remove MA from all of MemorySSA&#39;s lookup tables.
Definition: MemorySSA.cpp:1785
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:432
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:1564
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:211
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:1423
void dump() const
Definition: MemorySSA.cpp:2182
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:788
Represent the analysis usage information of a pass.
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2111
#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:1970
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:1220
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Definition: MemorySSA.cpp:2235
auto find_if_not(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range))
Definition: STLExtras.h:1225
virtual void invalidateInfo(MemoryAccess *)
Given a memory access, invalidate anything this walker knows about that access.
Definition: MemorySSA.h:1052
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
size_t size() const
Definition: SmallVector.h:52
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:1213
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:4351
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:1688
void optimizeUses()
Optimize uses to point to their actual clobbering definitions.
Definition: MemorySSA.cpp:1466
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:368
void setDefiningBlocks(const SmallPtrSetImpl< NodeTy *> &Blocks)
Give the IDF calculator the set of blocks in which the value is defined.
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:1905
void setDefiningAccess(MemoryAccess *DMA, bool Optimized=false, Optional< AliasResult > AR=MayAlias)
Definition: MemorySSA.h:299
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:1848
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:393
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:2051
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
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:2201
An analysis that produces MemorySSA for a function.
Definition: MemorySSA.h:924
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:374
BasicBlock * getBlock() const
Definition: MemorySSA.h:159
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
bool invalidate(Function &F, const PreservedAnalyses &PA, FunctionAnalysisManager::Invalidator &Inv)
Definition: MemorySSA.cpp:2218
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:111
MemoryAccess * getLiveOnEntryDef() const
Definition: MemorySSA.h:742
void print(raw_ostream &OS) const
Definition: MemorySSA.cpp:2169
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:1812
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:247
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:254
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:2269
iterator_range< def_chain_iterator< T > > def_chain(T MA, MemoryAccess *UpTo=nullptr)
Definition: MemorySSA.h:1297
cl::opt< bool > EnableMSSALoopDependency
Enables memory ssa as a dependency for loop passes.
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:2248
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:1657
MemoryAccess * getClobberingMemoryAccess(MemoryAccess *) override
Does the same thing as getClobberingMemoryAccess(const Instruction *I), but takes a MemoryAccess inst...
Definition: MemorySSA.cpp:2395
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:738
AnalysisUsage & addRequiredTransitive()
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:648
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:1023
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Definition: MemorySSA.cpp:2227
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This templated class represents "all analyses that operate over <a particular IR unit>" (e...
Definition: PassManager.h:91
Result run(Function &F, FunctionAnalysisManager &AM)
Definition: MemorySSA.cpp:2211
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:224
LLVM Value Representation.
Definition: Value.h:72
static MemoryLocOrCall getTombstoneKey()
Definition: MemorySSA.cpp:192
succ_range successors(Instruction *I)
Definition: CFG.h:259
upward_defs_iterator upward_defs_begin(const MemoryAccessPair &Pair)
Definition: MemorySSA.h:1242
AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB)
unsigned getID() const
Used for debugging and tracking things about MemoryAccesses.
Definition: MemorySSA.h:664
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:261
ModRefInfo
Flags indicating whether a memory access modifies or references memory.
static unsigned getHashValue(const MemoryLocOrCall &MLOC)
Definition: MemorySSA.cpp:196
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:212
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:1867
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:481
void print(raw_ostream &) const
Definition: MemorySSA.cpp:1839
This header defines various interfaces for pass management in LLVM.
#define LLVM_DEBUG(X)
Definition: Debug.h:122
static MemoryLocOrCall getEmptyKey()
Definition: MemorySSA.cpp:188
void insertIntoListsBefore(MemoryAccess *, const BasicBlock *, AccessList::iterator)
Definition: MemorySSA.cpp:1613
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:448
hexagon widen stores
reverse_iterator rbegin()
Definition: simple_ilist.h:121
std::pair< MemoryAccess *, MemoryLocation > MemoryAccessPair
Definition: MemorySSA.h:1073
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:2265
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:1251
LLVM_NODISCARD bool isRefSet(const ModRefInfo MRI)