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MemorySSAUpdater.cpp
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1 //===-- MemorySSAUpdater.cpp - Memory SSA Updater--------------------===//
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 MemorySSAUpdater class.
10 //
11 //===----------------------------------------------------------------===//
13 #include "llvm/ADT/STLExtras.h"
14 #include "llvm/ADT/SetVector.h"
15 #include "llvm/ADT/SmallPtrSet.h"
18 #include "llvm/IR/DataLayout.h"
19 #include "llvm/IR/Dominators.h"
20 #include "llvm/IR/GlobalVariable.h"
21 #include "llvm/IR/IRBuilder.h"
22 #include "llvm/IR/LLVMContext.h"
23 #include "llvm/IR/Metadata.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/Support/Debug.h"
27 #include <algorithm>
28 
29 #define DEBUG_TYPE "memoryssa"
30 using namespace llvm;
31 
32 // This is the marker algorithm from "Simple and Efficient Construction of
33 // Static Single Assignment Form"
34 // The simple, non-marker algorithm places phi nodes at any join
35 // Here, we place markers, and only place phi nodes if they end up necessary.
36 // They are only necessary if they break a cycle (IE we recursively visit
37 // ourselves again), or we discover, while getting the value of the operands,
38 // that there are two or more definitions needing to be merged.
39 // This still will leave non-minimal form in the case of irreducible control
40 // flow, where phi nodes may be in cycles with themselves, but unnecessary.
41 MemoryAccess *MemorySSAUpdater::getPreviousDefRecursive(
42  BasicBlock *BB,
43  DenseMap<BasicBlock *, TrackingVH<MemoryAccess>> &CachedPreviousDef) {
44  // First, do a cache lookup. Without this cache, certain CFG structures
45  // (like a series of if statements) take exponential time to visit.
46  auto Cached = CachedPreviousDef.find(BB);
47  if (Cached != CachedPreviousDef.end()) {
48  return Cached->second;
49  }
50 
51  if (BasicBlock *Pred = BB->getSinglePredecessor()) {
52  // Single predecessor case, just recurse, we can only have one definition.
53  MemoryAccess *Result = getPreviousDefFromEnd(Pred, CachedPreviousDef);
54  CachedPreviousDef.insert({BB, Result});
55  return Result;
56  }
57 
58  if (VisitedBlocks.count(BB)) {
59  // We hit our node again, meaning we had a cycle, we must insert a phi
60  // node to break it so we have an operand. The only case this will
61  // insert useless phis is if we have irreducible control flow.
62  MemoryAccess *Result = MSSA->createMemoryPhi(BB);
63  CachedPreviousDef.insert({BB, Result});
64  return Result;
65  }
66 
67  if (VisitedBlocks.insert(BB).second) {
68  // Mark us visited so we can detect a cycle
70 
71  // Recurse to get the values in our predecessors for placement of a
72  // potential phi node. This will insert phi nodes if we cycle in order to
73  // break the cycle and have an operand.
74  for (auto *Pred : predecessors(BB))
75  if (MSSA->DT->isReachableFromEntry(Pred))
76  PhiOps.push_back(getPreviousDefFromEnd(Pred, CachedPreviousDef));
77  else
78  PhiOps.push_back(MSSA->getLiveOnEntryDef());
79 
80  // Now try to simplify the ops to avoid placing a phi.
81  // This may return null if we never created a phi yet, that's okay
82  MemoryPhi *Phi = dyn_cast_or_null<MemoryPhi>(MSSA->getMemoryAccess(BB));
83 
84  // See if we can avoid the phi by simplifying it.
85  auto *Result = tryRemoveTrivialPhi(Phi, PhiOps);
86  // If we couldn't simplify, we may have to create a phi
87  if (Result == Phi) {
88  if (!Phi)
89  Phi = MSSA->createMemoryPhi(BB);
90 
91  // See if the existing phi operands match what we need.
92  // Unlike normal SSA, we only allow one phi node per block, so we can't just
93  // create a new one.
94  if (Phi->getNumOperands() != 0) {
95  // FIXME: Figure out whether this is dead code and if so remove it.
96  if (!std::equal(Phi->op_begin(), Phi->op_end(), PhiOps.begin())) {
97  // These will have been filled in by the recursive read we did above.
98  llvm::copy(PhiOps, Phi->op_begin());
99  std::copy(pred_begin(BB), pred_end(BB), Phi->block_begin());
100  }
101  } else {
102  unsigned i = 0;
103  for (auto *Pred : predecessors(BB))
104  Phi->addIncoming(&*PhiOps[i++], Pred);
105  InsertedPHIs.push_back(Phi);
106  }
107  Result = Phi;
108  }
109 
110  // Set ourselves up for the next variable by resetting visited state.
111  VisitedBlocks.erase(BB);
112  CachedPreviousDef.insert({BB, Result});
113  return Result;
114  }
115  llvm_unreachable("Should have hit one of the three cases above");
116 }
117 
118 // This starts at the memory access, and goes backwards in the block to find the
119 // previous definition. If a definition is not found the block of the access,
120 // it continues globally, creating phi nodes to ensure we have a single
121 // definition.
122 MemoryAccess *MemorySSAUpdater::getPreviousDef(MemoryAccess *MA) {
123  if (auto *LocalResult = getPreviousDefInBlock(MA))
124  return LocalResult;
126  return getPreviousDefRecursive(MA->getBlock(), CachedPreviousDef);
127 }
128 
129 // This starts at the memory access, and goes backwards in the block to the find
130 // the previous definition. If the definition is not found in the block of the
131 // access, it returns nullptr.
132 MemoryAccess *MemorySSAUpdater::getPreviousDefInBlock(MemoryAccess *MA) {
133  auto *Defs = MSSA->getWritableBlockDefs(MA->getBlock());
134 
135  // It's possible there are no defs, or we got handed the first def to start.
136  if (Defs) {
137  // If this is a def, we can just use the def iterators.
138  if (!isa<MemoryUse>(MA)) {
139  auto Iter = MA->getReverseDefsIterator();
140  ++Iter;
141  if (Iter != Defs->rend())
142  return &*Iter;
143  } else {
144  // Otherwise, have to walk the all access iterator.
145  auto End = MSSA->getWritableBlockAccesses(MA->getBlock())->rend();
146  for (auto &U : make_range(++MA->getReverseIterator(), End))
147  if (!isa<MemoryUse>(U))
148  return cast<MemoryAccess>(&U);
149  // Note that if MA comes before Defs->begin(), we won't hit a def.
150  return nullptr;
151  }
152  }
153  return nullptr;
154 }
155 
156 // This starts at the end of block
157 MemoryAccess *MemorySSAUpdater::getPreviousDefFromEnd(
158  BasicBlock *BB,
159  DenseMap<BasicBlock *, TrackingVH<MemoryAccess>> &CachedPreviousDef) {
160  auto *Defs = MSSA->getWritableBlockDefs(BB);
161 
162  if (Defs) {
163  CachedPreviousDef.insert({BB, &*Defs->rbegin()});
164  return &*Defs->rbegin();
165  }
166 
167  return getPreviousDefRecursive(BB, CachedPreviousDef);
168 }
169 // Recurse over a set of phi uses to eliminate the trivial ones
170 MemoryAccess *MemorySSAUpdater::recursePhi(MemoryAccess *Phi) {
171  if (!Phi)
172  return nullptr;
173  TrackingVH<MemoryAccess> Res(Phi);
175  std::copy(Phi->user_begin(), Phi->user_end(), std::back_inserter(Uses));
176  for (auto &U : Uses) {
177  if (MemoryPhi *UsePhi = dyn_cast<MemoryPhi>(&*U)) {
178  auto OperRange = UsePhi->operands();
179  tryRemoveTrivialPhi(UsePhi, OperRange);
180  }
181  }
182  return Res;
183 }
184 
185 // Eliminate trivial phis
186 // Phis are trivial if they are defined either by themselves, or all the same
187 // argument.
188 // IE phi(a, a) or b = phi(a, b) or c = phi(a, a, c)
189 // We recursively try to remove them.
190 template <class RangeType>
191 MemoryAccess *MemorySSAUpdater::tryRemoveTrivialPhi(MemoryPhi *Phi,
192  RangeType &Operands) {
193  // Bail out on non-opt Phis.
194  if (NonOptPhis.count(Phi))
195  return Phi;
196 
197  // Detect equal or self arguments
198  MemoryAccess *Same = nullptr;
199  for (auto &Op : Operands) {
200  // If the same or self, good so far
201  if (Op == Phi || Op == Same)
202  continue;
203  // not the same, return the phi since it's not eliminatable by us
204  if (Same)
205  return Phi;
206  Same = cast<MemoryAccess>(&*Op);
207  }
208  // Never found a non-self reference, the phi is undef
209  if (Same == nullptr)
210  return MSSA->getLiveOnEntryDef();
211  if (Phi) {
212  Phi->replaceAllUsesWith(Same);
213  removeMemoryAccess(Phi);
214  }
215 
216  // We should only end up recursing in case we replaced something, in which
217  // case, we may have made other Phis trivial.
218  return recursePhi(Same);
219 }
220 
222  InsertedPHIs.clear();
223  MU->setDefiningAccess(getPreviousDef(MU));
224  // Unlike for defs, there is no extra work to do. Because uses do not create
225  // new may-defs, there are only two cases:
226  //
227  // 1. There was a def already below us, and therefore, we should not have
228  // created a phi node because it was already needed for the def.
229  //
230  // 2. There is no def below us, and therefore, there is no extra renaming work
231  // to do.
232 }
233 
234 // Set every incoming edge {BB, MP->getBlock()} of MemoryPhi MP to NewDef.
235 static void setMemoryPhiValueForBlock(MemoryPhi *MP, const BasicBlock *BB,
236  MemoryAccess *NewDef) {
237  // Replace any operand with us an incoming block with the new defining
238  // access.
239  int i = MP->getBasicBlockIndex(BB);
240  assert(i != -1 && "Should have found the basic block in the phi");
241  // We can't just compare i against getNumOperands since one is signed and the
242  // other not. So use it to index into the block iterator.
243  for (auto BBIter = MP->block_begin() + i; BBIter != MP->block_end();
244  ++BBIter) {
245  if (*BBIter != BB)
246  break;
247  MP->setIncomingValue(i, NewDef);
248  ++i;
249  }
250 }
251 
252 // A brief description of the algorithm:
253 // First, we compute what should define the new def, using the SSA
254 // construction algorithm.
255 // Then, we update the defs below us (and any new phi nodes) in the graph to
256 // point to the correct new defs, to ensure we only have one variable, and no
257 // disconnected stores.
258 void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
259  InsertedPHIs.clear();
260 
261  // See if we had a local def, and if not, go hunting.
262  MemoryAccess *DefBefore = getPreviousDef(MD);
263  bool DefBeforeSameBlock = DefBefore->getBlock() == MD->getBlock();
264 
265  // There is a def before us, which means we can replace any store/phi uses
266  // of that thing with us, since we are in the way of whatever was there
267  // before.
268  // We now define that def's memorydefs and memoryphis
269  if (DefBeforeSameBlock) {
270  for (auto UI = DefBefore->use_begin(), UE = DefBefore->use_end();
271  UI != UE;) {
272  Use &U = *UI++;
273  // Leave the MemoryUses alone.
274  // Also make sure we skip ourselves to avoid self references.
275  if (isa<MemoryUse>(U.getUser()) || U.getUser() == MD)
276  continue;
277  // Defs are automatically unoptimized when the user is set to MD below,
278  // because the isOptimized() call will fail to find the same ID.
279  U.set(MD);
280  }
281  }
282 
283  // and that def is now our defining access.
284  MD->setDefiningAccess(DefBefore);
285 
286  // Remember the index where we may insert new phis below.
287  unsigned NewPhiIndex = InsertedPHIs.size();
288 
289  SmallVector<WeakVH, 8> FixupList(InsertedPHIs.begin(), InsertedPHIs.end());
290  if (!DefBeforeSameBlock) {
291  // If there was a local def before us, we must have the same effect it
292  // did. Because every may-def is the same, any phis/etc we would create, it
293  // would also have created. If there was no local def before us, we
294  // performed a global update, and have to search all successors and make
295  // sure we update the first def in each of them (following all paths until
296  // we hit the first def along each path). This may also insert phi nodes.
297  // TODO: There are other cases we can skip this work, such as when we have a
298  // single successor, and only used a straight line of single pred blocks
299  // backwards to find the def. To make that work, we'd have to track whether
300  // getDefRecursive only ever used the single predecessor case. These types
301  // of paths also only exist in between CFG simplifications.
302 
303  // If this is the first def in the block and this insert is in an arbitrary
304  // place, compute IDF and place phis.
305  auto Iter = MD->getDefsIterator();
306  ++Iter;
307  auto IterEnd = MSSA->getBlockDefs(MD->getBlock())->end();
308  if (Iter == IterEnd) {
309  ForwardIDFCalculator IDFs(*MSSA->DT);
311  SmallPtrSet<BasicBlock *, 2> DefiningBlocks;
312  DefiningBlocks.insert(MD->getBlock());
313  IDFs.setDefiningBlocks(DefiningBlocks);
314  IDFs.calculate(IDFBlocks);
315  SmallVector<AssertingVH<MemoryPhi>, 4> NewInsertedPHIs;
316  for (auto *BBIDF : IDFBlocks)
317  if (!MSSA->getMemoryAccess(BBIDF)) {
318  auto *MPhi = MSSA->createMemoryPhi(BBIDF);
319  NewInsertedPHIs.push_back(MPhi);
320  // Add the phis created into the IDF blocks to NonOptPhis, so they are
321  // not optimized out as trivial by the call to getPreviousDefFromEnd
322  // below. Once they are complete, all these Phis are added to the
323  // FixupList, and removed from NonOptPhis inside fixupDefs().
324  NonOptPhis.insert(MPhi);
325  }
326 
327  for (auto &MPhi : NewInsertedPHIs) {
328  auto *BBIDF = MPhi->getBlock();
329  for (auto *Pred : predecessors(BBIDF)) {
331  MPhi->addIncoming(getPreviousDefFromEnd(Pred, CachedPreviousDef),
332  Pred);
333  }
334  }
335 
336  // Re-take the index where we're adding the new phis, because the above
337  // call to getPreviousDefFromEnd, may have inserted into InsertedPHIs.
338  NewPhiIndex = InsertedPHIs.size();
339  for (auto &MPhi : NewInsertedPHIs) {
340  InsertedPHIs.push_back(&*MPhi);
341  FixupList.push_back(&*MPhi);
342  }
343  }
344 
345  FixupList.push_back(MD);
346  }
347 
348  // Remember the index where we stopped inserting new phis above, since the
349  // fixupDefs call in the loop below may insert more, that are already minimal.
350  unsigned NewPhiIndexEnd = InsertedPHIs.size();
351 
352  while (!FixupList.empty()) {
353  unsigned StartingPHISize = InsertedPHIs.size();
354  fixupDefs(FixupList);
355  FixupList.clear();
356  // Put any new phis on the fixup list, and process them
357  FixupList.append(InsertedPHIs.begin() + StartingPHISize, InsertedPHIs.end());
358  }
359 
360  // Optimize potentially non-minimal phis added in this method.
361  unsigned NewPhiSize = NewPhiIndexEnd - NewPhiIndex;
362  if (NewPhiSize)
363  tryRemoveTrivialPhis(ArrayRef<WeakVH>(&InsertedPHIs[NewPhiIndex], NewPhiSize));
364 
365  // Now that all fixups are done, rename all uses if we are asked.
366  if (RenameUses) {
368  BasicBlock *StartBlock = MD->getBlock();
369  // We are guaranteed there is a def in the block, because we just got it
370  // handed to us in this function.
371  MemoryAccess *FirstDef = &*MSSA->getWritableBlockDefs(StartBlock)->begin();
372  // Convert to incoming value if it's a memorydef. A phi *is* already an
373  // incoming value.
374  if (auto *MD = dyn_cast<MemoryDef>(FirstDef))
375  FirstDef = MD->getDefiningAccess();
376 
377  MSSA->renamePass(MD->getBlock(), FirstDef, Visited);
378  // We just inserted a phi into this block, so the incoming value will become
379  // the phi anyway, so it does not matter what we pass.
380  for (auto &MP : InsertedPHIs) {
381  MemoryPhi *Phi = dyn_cast_or_null<MemoryPhi>(MP);
382  if (Phi)
383  MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
384  }
385  }
386 }
387 
388 void MemorySSAUpdater::fixupDefs(const SmallVectorImpl<WeakVH> &Vars) {
391  for (auto &Var : Vars) {
392  MemoryAccess *NewDef = dyn_cast_or_null<MemoryAccess>(Var);
393  if (!NewDef)
394  continue;
395  // First, see if there is a local def after the operand.
396  auto *Defs = MSSA->getWritableBlockDefs(NewDef->getBlock());
397  auto DefIter = NewDef->getDefsIterator();
398 
399  // The temporary Phi is being fixed, unmark it for not to optimize.
400  if (MemoryPhi *Phi = dyn_cast<MemoryPhi>(NewDef))
401  NonOptPhis.erase(Phi);
402 
403  // If there is a local def after us, we only have to rename that.
404  if (++DefIter != Defs->end()) {
405  cast<MemoryDef>(DefIter)->setDefiningAccess(NewDef);
406  continue;
407  }
408 
409  // Otherwise, we need to search down through the CFG.
410  // For each of our successors, handle it directly if their is a phi, or
411  // place on the fixup worklist.
412  for (const auto *S : successors(NewDef->getBlock())) {
413  if (auto *MP = MSSA->getMemoryAccess(S))
414  setMemoryPhiValueForBlock(MP, NewDef->getBlock(), NewDef);
415  else
416  Worklist.push_back(S);
417  }
418 
419  while (!Worklist.empty()) {
420  const BasicBlock *FixupBlock = Worklist.back();
421  Worklist.pop_back();
422 
423  // Get the first def in the block that isn't a phi node.
424  if (auto *Defs = MSSA->getWritableBlockDefs(FixupBlock)) {
425  auto *FirstDef = &*Defs->begin();
426  // The loop above and below should have taken care of phi nodes
427  assert(!isa<MemoryPhi>(FirstDef) &&
428  "Should have already handled phi nodes!");
429  // We are now this def's defining access, make sure we actually dominate
430  // it
431  assert(MSSA->dominates(NewDef, FirstDef) &&
432  "Should have dominated the new access");
433 
434  // This may insert new phi nodes, because we are not guaranteed the
435  // block we are processing has a single pred, and depending where the
436  // store was inserted, it may require phi nodes below it.
437  cast<MemoryDef>(FirstDef)->setDefiningAccess(getPreviousDef(FirstDef));
438  return;
439  }
440  // We didn't find a def, so we must continue.
441  for (const auto *S : successors(FixupBlock)) {
442  // If there is a phi node, handle it.
443  // Otherwise, put the block on the worklist
444  if (auto *MP = MSSA->getMemoryAccess(S))
445  setMemoryPhiValueForBlock(MP, FixupBlock, NewDef);
446  else {
447  // If we cycle, we should have ended up at a phi node that we already
448  // processed. FIXME: Double check this
449  if (!Seen.insert(S).second)
450  continue;
451  Worklist.push_back(S);
452  }
453  }
454  }
455  }
456 }
457 
459  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(To)) {
460  MPhi->unorderedDeleteIncomingBlock(From);
461  if (MPhi->getNumIncomingValues() == 1)
462  removeMemoryAccess(MPhi);
463  }
464 }
465 
467  const BasicBlock *To) {
468  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(To)) {
469  bool Found = false;
470  MPhi->unorderedDeleteIncomingIf([&](const MemoryAccess *, BasicBlock *B) {
471  if (From != B)
472  return false;
473  if (Found)
474  return true;
475  Found = true;
476  return false;
477  });
478  if (MPhi->getNumIncomingValues() == 1)
479  removeMemoryAccess(MPhi);
480  }
481 }
482 
483 void MemorySSAUpdater::cloneUsesAndDefs(BasicBlock *BB, BasicBlock *NewBB,
484  const ValueToValueMapTy &VMap,
485  PhiToDefMap &MPhiMap,
486  bool CloneWasSimplified) {
487  auto GetNewDefiningAccess = [&](MemoryAccess *MA) -> MemoryAccess * {
488  MemoryAccess *InsnDefining = MA;
489  if (MemoryUseOrDef *DefMUD = dyn_cast<MemoryUseOrDef>(InsnDefining)) {
490  if (!MSSA->isLiveOnEntryDef(DefMUD)) {
491  Instruction *DefMUDI = DefMUD->getMemoryInst();
492  assert(DefMUDI && "Found MemoryUseOrDef with no Instruction.");
493  if (Instruction *NewDefMUDI =
494  cast_or_null<Instruction>(VMap.lookup(DefMUDI)))
495  InsnDefining = MSSA->getMemoryAccess(NewDefMUDI);
496  }
497  } else {
498  MemoryPhi *DefPhi = cast<MemoryPhi>(InsnDefining);
499  if (MemoryAccess *NewDefPhi = MPhiMap.lookup(DefPhi))
500  InsnDefining = NewDefPhi;
501  }
502  assert(InsnDefining && "Defining instruction cannot be nullptr.");
503  return InsnDefining;
504  };
505 
506  const MemorySSA::AccessList *Acc = MSSA->getBlockAccesses(BB);
507  if (!Acc)
508  return;
509  for (const MemoryAccess &MA : *Acc) {
510  if (const MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&MA)) {
511  Instruction *Insn = MUD->getMemoryInst();
512  // Entry does not exist if the clone of the block did not clone all
513  // instructions. This occurs in LoopRotate when cloning instructions
514  // from the old header to the old preheader. The cloned instruction may
515  // also be a simplified Value, not an Instruction (see LoopRotate).
516  // Also in LoopRotate, even when it's an instruction, due to it being
517  // simplified, it may be a Use rather than a Def, so we cannot use MUD as
518  // template. Calls coming from updateForClonedBlockIntoPred, ensure this.
519  if (Instruction *NewInsn =
520  dyn_cast_or_null<Instruction>(VMap.lookup(Insn))) {
521  MemoryAccess *NewUseOrDef = MSSA->createDefinedAccess(
522  NewInsn, GetNewDefiningAccess(MUD->getDefiningAccess()),
523  CloneWasSimplified ? nullptr : MUD);
524  MSSA->insertIntoListsForBlock(NewUseOrDef, NewBB, MemorySSA::End);
525  }
526  }
527  }
528 }
529 
531  BasicBlock *Header, BasicBlock *Preheader, BasicBlock *BEBlock) {
532  auto *MPhi = MSSA->getMemoryAccess(Header);
533  if (!MPhi)
534  return;
535 
536  // Create phi node in the backedge block and populate it with the same
537  // incoming values as MPhi. Skip incoming values coming from Preheader.
538  auto *NewMPhi = MSSA->createMemoryPhi(BEBlock);
539  bool HasUniqueIncomingValue = true;
540  MemoryAccess *UniqueValue = nullptr;
541  for (unsigned I = 0, E = MPhi->getNumIncomingValues(); I != E; ++I) {
542  BasicBlock *IBB = MPhi->getIncomingBlock(I);
543  MemoryAccess *IV = MPhi->getIncomingValue(I);
544  if (IBB != Preheader) {
545  NewMPhi->addIncoming(IV, IBB);
546  if (HasUniqueIncomingValue) {
547  if (!UniqueValue)
548  UniqueValue = IV;
549  else if (UniqueValue != IV)
550  HasUniqueIncomingValue = false;
551  }
552  }
553  }
554 
555  // Update incoming edges into MPhi. Remove all but the incoming edge from
556  // Preheader. Add an edge from NewMPhi
557  auto *AccFromPreheader = MPhi->getIncomingValueForBlock(Preheader);
558  MPhi->setIncomingValue(0, AccFromPreheader);
559  MPhi->setIncomingBlock(0, Preheader);
560  for (unsigned I = MPhi->getNumIncomingValues() - 1; I >= 1; --I)
561  MPhi->unorderedDeleteIncoming(I);
562  MPhi->addIncoming(NewMPhi, BEBlock);
563 
564  // If NewMPhi is a trivial phi, remove it. Its use in the header MPhi will be
565  // replaced with the unique value.
566  if (HasUniqueIncomingValue)
567  removeMemoryAccess(NewMPhi);
568 }
569 
571  ArrayRef<BasicBlock *> ExitBlocks,
572  const ValueToValueMapTy &VMap,
573  bool IgnoreIncomingWithNoClones) {
574  PhiToDefMap MPhiMap;
575 
576  auto FixPhiIncomingValues = [&](MemoryPhi *Phi, MemoryPhi *NewPhi) {
577  assert(Phi && NewPhi && "Invalid Phi nodes.");
578  BasicBlock *NewPhiBB = NewPhi->getBlock();
579  SmallPtrSet<BasicBlock *, 4> NewPhiBBPreds(pred_begin(NewPhiBB),
580  pred_end(NewPhiBB));
581  for (unsigned It = 0, E = Phi->getNumIncomingValues(); It < E; ++It) {
582  MemoryAccess *IncomingAccess = Phi->getIncomingValue(It);
583  BasicBlock *IncBB = Phi->getIncomingBlock(It);
584 
585  if (BasicBlock *NewIncBB = cast_or_null<BasicBlock>(VMap.lookup(IncBB)))
586  IncBB = NewIncBB;
587  else if (IgnoreIncomingWithNoClones)
588  continue;
589 
590  // Now we have IncBB, and will need to add incoming from it to NewPhi.
591 
592  // If IncBB is not a predecessor of NewPhiBB, then do not add it.
593  // NewPhiBB was cloned without that edge.
594  if (!NewPhiBBPreds.count(IncBB))
595  continue;
596 
597  // Determine incoming value and add it as incoming from IncBB.
598  if (MemoryUseOrDef *IncMUD = dyn_cast<MemoryUseOrDef>(IncomingAccess)) {
599  if (!MSSA->isLiveOnEntryDef(IncMUD)) {
600  Instruction *IncI = IncMUD->getMemoryInst();
601  assert(IncI && "Found MemoryUseOrDef with no Instruction.");
602  if (Instruction *NewIncI =
603  cast_or_null<Instruction>(VMap.lookup(IncI))) {
604  IncMUD = MSSA->getMemoryAccess(NewIncI);
605  assert(IncMUD &&
606  "MemoryUseOrDef cannot be null, all preds processed.");
607  }
608  }
609  NewPhi->addIncoming(IncMUD, IncBB);
610  } else {
611  MemoryPhi *IncPhi = cast<MemoryPhi>(IncomingAccess);
612  if (MemoryAccess *NewDefPhi = MPhiMap.lookup(IncPhi))
613  NewPhi->addIncoming(NewDefPhi, IncBB);
614  else
615  NewPhi->addIncoming(IncPhi, IncBB);
616  }
617  }
618  };
619 
620  auto ProcessBlock = [&](BasicBlock *BB) {
621  BasicBlock *NewBlock = cast_or_null<BasicBlock>(VMap.lookup(BB));
622  if (!NewBlock)
623  return;
624 
625  assert(!MSSA->getWritableBlockAccesses(NewBlock) &&
626  "Cloned block should have no accesses");
627 
628  // Add MemoryPhi.
629  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB)) {
630  MemoryPhi *NewPhi = MSSA->createMemoryPhi(NewBlock);
631  MPhiMap[MPhi] = NewPhi;
632  }
633  // Update Uses and Defs.
634  cloneUsesAndDefs(BB, NewBlock, VMap, MPhiMap);
635  };
636 
637  for (auto BB : llvm::concat<BasicBlock *const>(LoopBlocks, ExitBlocks))
638  ProcessBlock(BB);
639 
640  for (auto BB : llvm::concat<BasicBlock *const>(LoopBlocks, ExitBlocks))
641  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB))
642  if (MemoryAccess *NewPhi = MPhiMap.lookup(MPhi))
643  FixPhiIncomingValues(MPhi, cast<MemoryPhi>(NewPhi));
644 }
645 
647  BasicBlock *BB, BasicBlock *P1, const ValueToValueMapTy &VM) {
648  // All defs/phis from outside BB that are used in BB, are valid uses in P1.
649  // Since those defs/phis must have dominated BB, and also dominate P1.
650  // Defs from BB being used in BB will be replaced with the cloned defs from
651  // VM. The uses of BB's Phi (if it exists) in BB will be replaced by the
652  // incoming def into the Phi from P1.
653  // Instructions cloned into the predecessor are in practice sometimes
654  // simplified, so disable the use of the template, and create an access from
655  // scratch.
656  PhiToDefMap MPhiMap;
657  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB))
658  MPhiMap[MPhi] = MPhi->getIncomingValueForBlock(P1);
659  cloneUsesAndDefs(BB, P1, VM, MPhiMap, /*CloneWasSimplified=*/true);
660 }
661 
662 template <typename Iter>
663 void MemorySSAUpdater::privateUpdateExitBlocksForClonedLoop(
664  ArrayRef<BasicBlock *> ExitBlocks, Iter ValuesBegin, Iter ValuesEnd,
665  DominatorTree &DT) {
667  // Update/insert phis in all successors of exit blocks.
668  for (auto *Exit : ExitBlocks)
669  for (const ValueToValueMapTy *VMap : make_range(ValuesBegin, ValuesEnd))
670  if (BasicBlock *NewExit = cast_or_null<BasicBlock>(VMap->lookup(Exit))) {
671  BasicBlock *ExitSucc = NewExit->getTerminator()->getSuccessor(0);
672  Updates.push_back({DT.Insert, NewExit, ExitSucc});
673  }
674  applyInsertUpdates(Updates, DT);
675 }
676 
678  ArrayRef<BasicBlock *> ExitBlocks, const ValueToValueMapTy &VMap,
679  DominatorTree &DT) {
680  const ValueToValueMapTy *const Arr[] = {&VMap};
681  privateUpdateExitBlocksForClonedLoop(ExitBlocks, std::begin(Arr),
682  std::end(Arr), DT);
683 }
684 
686  ArrayRef<BasicBlock *> ExitBlocks,
687  ArrayRef<std::unique_ptr<ValueToValueMapTy>> VMaps, DominatorTree &DT) {
688  auto GetPtr = [&](const std::unique_ptr<ValueToValueMapTy> &I) {
689  return I.get();
690  };
691  using MappedIteratorType =
693  decltype(GetPtr)>;
694  auto MapBegin = MappedIteratorType(VMaps.begin(), GetPtr);
695  auto MapEnd = MappedIteratorType(VMaps.end(), GetPtr);
696  privateUpdateExitBlocksForClonedLoop(ExitBlocks, MapBegin, MapEnd, DT);
697 }
698 
700  DominatorTree &DT) {
701  SmallVector<CFGUpdate, 4> RevDeleteUpdates;
702  SmallVector<CFGUpdate, 4> InsertUpdates;
703  for (auto &Update : Updates) {
704  if (Update.getKind() == DT.Insert)
705  InsertUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
706  else
707  RevDeleteUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
708  }
709 
710  if (!RevDeleteUpdates.empty()) {
711  // Update for inserted edges: use newDT and snapshot CFG as if deletes had
712  // not occurred.
713  // FIXME: This creates a new DT, so it's more expensive to do mix
714  // delete/inserts vs just inserts. We can do an incremental update on the DT
715  // to revert deletes, than re-delete the edges. Teaching DT to do this, is
716  // part of a pending cleanup.
717  DominatorTree NewDT(DT, RevDeleteUpdates);
718  GraphDiff<BasicBlock *> GD(RevDeleteUpdates);
719  applyInsertUpdates(InsertUpdates, NewDT, &GD);
720  } else {
722  applyInsertUpdates(InsertUpdates, DT, &GD);
723  }
724 
725  // Update for deleted edges
726  for (auto &Update : RevDeleteUpdates)
727  removeEdge(Update.getFrom(), Update.getTo());
728 }
729 
731  DominatorTree &DT) {
733  applyInsertUpdates(Updates, DT, &GD);
734 }
735 
737  DominatorTree &DT,
738  const GraphDiff<BasicBlock *> *GD) {
739  // Get recursive last Def, assuming well formed MSSA and updated DT.
740  auto GetLastDef = [&](BasicBlock *BB) -> MemoryAccess * {
741  while (true) {
742  MemorySSA::DefsList *Defs = MSSA->getWritableBlockDefs(BB);
743  // Return last Def or Phi in BB, if it exists.
744  if (Defs)
745  return &*(--Defs->end());
746 
747  // Check number of predecessors, we only care if there's more than one.
748  unsigned Count = 0;
749  BasicBlock *Pred = nullptr;
750  for (auto &Pair : children<GraphDiffInvBBPair>({GD, BB})) {
751  Pred = Pair.second;
752  Count++;
753  if (Count == 2)
754  break;
755  }
756 
757  // If BB has multiple predecessors, get last definition from IDom.
758  if (Count != 1) {
759  // [SimpleLoopUnswitch] If BB is a dead block, about to be deleted, its
760  // DT is invalidated. Return LoE as its last def. This will be added to
761  // MemoryPhi node, and later deleted when the block is deleted.
762  if (!DT.getNode(BB))
763  return MSSA->getLiveOnEntryDef();
764  if (auto *IDom = DT.getNode(BB)->getIDom())
765  if (IDom->getBlock() != BB) {
766  BB = IDom->getBlock();
767  continue;
768  }
769  return MSSA->getLiveOnEntryDef();
770  } else {
771  // Single predecessor, BB cannot be dead. GetLastDef of Pred.
772  assert(Count == 1 && Pred && "Single predecessor expected.");
773  BB = Pred;
774  }
775  };
776  llvm_unreachable("Unable to get last definition.");
777  };
778 
779  // Get nearest IDom given a set of blocks.
780  // TODO: this can be optimized by starting the search at the node with the
781  // lowest level (highest in the tree).
782  auto FindNearestCommonDominator =
783  [&](const SmallSetVector<BasicBlock *, 2> &BBSet) -> BasicBlock * {
784  BasicBlock *PrevIDom = *BBSet.begin();
785  for (auto *BB : BBSet)
786  PrevIDom = DT.findNearestCommonDominator(PrevIDom, BB);
787  return PrevIDom;
788  };
789 
790  // Get all blocks that dominate PrevIDom, stop when reaching CurrIDom. Do not
791  // include CurrIDom.
792  auto GetNoLongerDomBlocks =
793  [&](BasicBlock *PrevIDom, BasicBlock *CurrIDom,
794  SmallVectorImpl<BasicBlock *> &BlocksPrevDom) {
795  if (PrevIDom == CurrIDom)
796  return;
797  BlocksPrevDom.push_back(PrevIDom);
798  BasicBlock *NextIDom = PrevIDom;
799  while (BasicBlock *UpIDom =
800  DT.getNode(NextIDom)->getIDom()->getBlock()) {
801  if (UpIDom == CurrIDom)
802  break;
803  BlocksPrevDom.push_back(UpIDom);
804  NextIDom = UpIDom;
805  }
806  };
807 
808  // Map a BB to its predecessors: added + previously existing. To get a
809  // deterministic order, store predecessors as SetVectors. The order in each
810  // will be defined by the order in Updates (fixed) and the order given by
811  // children<> (also fixed). Since we further iterate over these ordered sets,
812  // we lose the information of multiple edges possibly existing between two
813  // blocks, so we'll keep and EdgeCount map for that.
814  // An alternate implementation could keep unordered set for the predecessors,
815  // traverse either Updates or children<> each time to get the deterministic
816  // order, and drop the usage of EdgeCount. This alternate approach would still
817  // require querying the maps for each predecessor, and children<> call has
818  // additional computation inside for creating the snapshot-graph predecessors.
819  // As such, we favor using a little additional storage and less compute time.
820  // This decision can be revisited if we find the alternative more favorable.
821 
822  struct PredInfo {
825  };
827 
828  for (auto &Edge : Updates) {
829  BasicBlock *BB = Edge.getTo();
830  auto &AddedBlockSet = PredMap[BB].Added;
831  AddedBlockSet.insert(Edge.getFrom());
832  }
833 
834  // Store all existing predecessor for each BB, at least one must exist.
837  for (auto &BBPredPair : PredMap) {
838  auto *BB = BBPredPair.first;
839  const auto &AddedBlockSet = BBPredPair.second.Added;
840  auto &PrevBlockSet = BBPredPair.second.Prev;
841  for (auto &Pair : children<GraphDiffInvBBPair>({GD, BB})) {
842  BasicBlock *Pi = Pair.second;
843  if (!AddedBlockSet.count(Pi))
844  PrevBlockSet.insert(Pi);
845  EdgeCountMap[{Pi, BB}]++;
846  }
847 
848  if (PrevBlockSet.empty()) {
849  assert(pred_size(BB) == AddedBlockSet.size() && "Duplicate edges added.");
850  LLVM_DEBUG(
851  dbgs()
852  << "Adding a predecessor to a block with no predecessors. "
853  "This must be an edge added to a new, likely cloned, block. "
854  "Its memory accesses must be already correct, assuming completed "
855  "via the updateExitBlocksForClonedLoop API. "
856  "Assert a single such edge is added so no phi addition or "
857  "additional processing is required.\n");
858  assert(AddedBlockSet.size() == 1 &&
859  "Can only handle adding one predecessor to a new block.");
860  // Need to remove new blocks from PredMap. Remove below to not invalidate
861  // iterator here.
862  NewBlocks.insert(BB);
863  }
864  }
865  // Nothing to process for new/cloned blocks.
866  for (auto *BB : NewBlocks)
867  PredMap.erase(BB);
868 
869  SmallVector<BasicBlock *, 16> BlocksWithDefsToReplace;
870  SmallVector<WeakVH, 8> InsertedPhis;
871 
872  // First create MemoryPhis in all blocks that don't have one. Create in the
873  // order found in Updates, not in PredMap, to get deterministic numbering.
874  for (auto &Edge : Updates) {
875  BasicBlock *BB = Edge.getTo();
876  if (PredMap.count(BB) && !MSSA->getMemoryAccess(BB))
877  InsertedPhis.push_back(MSSA->createMemoryPhi(BB));
878  }
879 
880  // Now we'll fill in the MemoryPhis with the right incoming values.
881  for (auto &BBPredPair : PredMap) {
882  auto *BB = BBPredPair.first;
883  const auto &PrevBlockSet = BBPredPair.second.Prev;
884  const auto &AddedBlockSet = BBPredPair.second.Added;
885  assert(!PrevBlockSet.empty() &&
886  "At least one previous predecessor must exist.");
887 
888  // TODO: if this becomes a bottleneck, we can save on GetLastDef calls by
889  // keeping this map before the loop. We can reuse already populated entries
890  // if an edge is added from the same predecessor to two different blocks,
891  // and this does happen in rotate. Note that the map needs to be updated
892  // when deleting non-necessary phis below, if the phi is in the map by
893  // replacing the value with DefP1.
895  for (auto *AddedPred : AddedBlockSet) {
896  auto *DefPn = GetLastDef(AddedPred);
897  assert(DefPn != nullptr && "Unable to find last definition.");
898  LastDefAddedPred[AddedPred] = DefPn;
899  }
900 
901  MemoryPhi *NewPhi = MSSA->getMemoryAccess(BB);
902  // If Phi is not empty, add an incoming edge from each added pred. Must
903  // still compute blocks with defs to replace for this block below.
904  if (NewPhi->getNumOperands()) {
905  for (auto *Pred : AddedBlockSet) {
906  auto *LastDefForPred = LastDefAddedPred[Pred];
907  for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
908  NewPhi->addIncoming(LastDefForPred, Pred);
909  }
910  } else {
911  // Pick any existing predecessor and get its definition. All other
912  // existing predecessors should have the same one, since no phi existed.
913  auto *P1 = *PrevBlockSet.begin();
914  MemoryAccess *DefP1 = GetLastDef(P1);
915 
916  // Check DefP1 against all Defs in LastDefPredPair. If all the same,
917  // nothing to add.
918  bool InsertPhi = false;
919  for (auto LastDefPredPair : LastDefAddedPred)
920  if (DefP1 != LastDefPredPair.second) {
921  InsertPhi = true;
922  break;
923  }
924  if (!InsertPhi) {
925  // Since NewPhi may be used in other newly added Phis, replace all uses
926  // of NewPhi with the definition coming from all predecessors (DefP1),
927  // before deleting it.
928  NewPhi->replaceAllUsesWith(DefP1);
929  removeMemoryAccess(NewPhi);
930  continue;
931  }
932 
933  // Update Phi with new values for new predecessors and old value for all
934  // other predecessors. Since AddedBlockSet and PrevBlockSet are ordered
935  // sets, the order of entries in NewPhi is deterministic.
936  for (auto *Pred : AddedBlockSet) {
937  auto *LastDefForPred = LastDefAddedPred[Pred];
938  for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
939  NewPhi->addIncoming(LastDefForPred, Pred);
940  }
941  for (auto *Pred : PrevBlockSet)
942  for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
943  NewPhi->addIncoming(DefP1, Pred);
944  }
945 
946  // Get all blocks that used to dominate BB and no longer do after adding
947  // AddedBlockSet, where PrevBlockSet are the previously known predecessors.
948  assert(DT.getNode(BB)->getIDom() && "BB does not have valid idom");
949  BasicBlock *PrevIDom = FindNearestCommonDominator(PrevBlockSet);
950  assert(PrevIDom && "Previous IDom should exists");
951  BasicBlock *NewIDom = DT.getNode(BB)->getIDom()->getBlock();
952  assert(NewIDom && "BB should have a new valid idom");
953  assert(DT.dominates(NewIDom, PrevIDom) &&
954  "New idom should dominate old idom");
955  GetNoLongerDomBlocks(PrevIDom, NewIDom, BlocksWithDefsToReplace);
956  }
957 
958  tryRemoveTrivialPhis(InsertedPhis);
959  // Create the set of blocks that now have a definition. We'll use this to
960  // compute IDF and add Phis there next.
961  SmallVector<BasicBlock *, 8> BlocksToProcess;
962  for (auto &VH : InsertedPhis)
963  if (auto *MPhi = cast_or_null<MemoryPhi>(VH))
964  BlocksToProcess.push_back(MPhi->getBlock());
965 
966  // Compute IDF and add Phis in all IDF blocks that do not have one.
968  if (!BlocksToProcess.empty()) {
969  ForwardIDFCalculator IDFs(DT, GD);
970  SmallPtrSet<BasicBlock *, 16> DefiningBlocks(BlocksToProcess.begin(),
971  BlocksToProcess.end());
972  IDFs.setDefiningBlocks(DefiningBlocks);
973  IDFs.calculate(IDFBlocks);
974 
976  // First create all needed Phis.
977  for (auto *BBIDF : IDFBlocks)
978  if (!MSSA->getMemoryAccess(BBIDF)) {
979  auto *IDFPhi = MSSA->createMemoryPhi(BBIDF);
980  InsertedPhis.push_back(IDFPhi);
981  PhisToFill.insert(IDFPhi);
982  }
983  // Then update or insert their correct incoming values.
984  for (auto *BBIDF : IDFBlocks) {
985  auto *IDFPhi = MSSA->getMemoryAccess(BBIDF);
986  assert(IDFPhi && "Phi must exist");
987  if (!PhisToFill.count(IDFPhi)) {
988  // Update existing Phi.
989  // FIXME: some updates may be redundant, try to optimize and skip some.
990  for (unsigned I = 0, E = IDFPhi->getNumIncomingValues(); I < E; ++I)
991  IDFPhi->setIncomingValue(I, GetLastDef(IDFPhi->getIncomingBlock(I)));
992  } else {
993  for (auto &Pair : children<GraphDiffInvBBPair>({GD, BBIDF})) {
994  BasicBlock *Pi = Pair.second;
995  IDFPhi->addIncoming(GetLastDef(Pi), Pi);
996  }
997  }
998  }
999  }
1000 
1001  // Now for all defs in BlocksWithDefsToReplace, if there are uses they no
1002  // longer dominate, replace those with the closest dominating def.
1003  // This will also update optimized accesses, as they're also uses.
1004  for (auto *BlockWithDefsToReplace : BlocksWithDefsToReplace) {
1005  if (auto DefsList = MSSA->getWritableBlockDefs(BlockWithDefsToReplace)) {
1006  for (auto &DefToReplaceUses : *DefsList) {
1007  BasicBlock *DominatingBlock = DefToReplaceUses.getBlock();
1008  Value::use_iterator UI = DefToReplaceUses.use_begin(),
1009  E = DefToReplaceUses.use_end();
1010  for (; UI != E;) {
1011  Use &U = *UI;
1012  ++UI;
1014  if (MemoryPhi *UsrPhi = dyn_cast<MemoryPhi>(Usr)) {
1015  BasicBlock *DominatedBlock = UsrPhi->getIncomingBlock(U);
1016  if (!DT.dominates(DominatingBlock, DominatedBlock))
1017  U.set(GetLastDef(DominatedBlock));
1018  } else {
1019  BasicBlock *DominatedBlock = Usr->getBlock();
1020  if (!DT.dominates(DominatingBlock, DominatedBlock)) {
1021  if (auto *DomBlPhi = MSSA->getMemoryAccess(DominatedBlock))
1022  U.set(DomBlPhi);
1023  else {
1024  auto *IDom = DT.getNode(DominatedBlock)->getIDom();
1025  assert(IDom && "Block must have a valid IDom.");
1026  U.set(GetLastDef(IDom->getBlock()));
1027  }
1028  cast<MemoryUseOrDef>(Usr)->resetOptimized();
1029  }
1030  }
1031  }
1032  }
1033  }
1034  }
1035  tryRemoveTrivialPhis(InsertedPhis);
1036 }
1037 
1038 // Move What before Where in the MemorySSA IR.
1039 template <class WhereType>
1040 void MemorySSAUpdater::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
1041  WhereType Where) {
1042  // Mark MemoryPhi users of What not to be optimized.
1043  for (auto *U : What->users())
1044  if (MemoryPhi *PhiUser = dyn_cast<MemoryPhi>(U))
1045  NonOptPhis.insert(PhiUser);
1046 
1047  // Replace all our users with our defining access.
1048  What->replaceAllUsesWith(What->getDefiningAccess());
1049 
1050  // Let MemorySSA take care of moving it around in the lists.
1051  MSSA->moveTo(What, BB, Where);
1052 
1053  // Now reinsert it into the IR and do whatever fixups needed.
1054  if (auto *MD = dyn_cast<MemoryDef>(What))
1055  insertDef(MD);
1056  else
1057  insertUse(cast<MemoryUse>(What));
1058 
1059  // Clear dangling pointers. We added all MemoryPhi users, but not all
1060  // of them are removed by fixupDefs().
1061  NonOptPhis.clear();
1062 }
1063 
1064 // Move What before Where in the MemorySSA IR.
1066  moveTo(What, Where->getBlock(), Where->getIterator());
1067 }
1068 
1069 // Move What after Where in the MemorySSA IR.
1071  moveTo(What, Where->getBlock(), ++Where->getIterator());
1072 }
1073 
1075  MemorySSA::InsertionPlace Where) {
1076  return moveTo(What, BB, Where);
1077 }
1078 
1079 // All accesses in To used to be in From. Move to end and update access lists.
1080 void MemorySSAUpdater::moveAllAccesses(BasicBlock *From, BasicBlock *To,
1081  Instruction *Start) {
1082 
1083  MemorySSA::AccessList *Accs = MSSA->getWritableBlockAccesses(From);
1084  if (!Accs)
1085  return;
1086 
1087  MemoryAccess *FirstInNew = nullptr;
1088  for (Instruction &I : make_range(Start->getIterator(), To->end()))
1089  if ((FirstInNew = MSSA->getMemoryAccess(&I)))
1090  break;
1091  if (!FirstInNew)
1092  return;
1093 
1094  auto *MUD = cast<MemoryUseOrDef>(FirstInNew);
1095  do {
1096  auto NextIt = ++MUD->getIterator();
1097  MemoryUseOrDef *NextMUD = (!Accs || NextIt == Accs->end())
1098  ? nullptr
1099  : cast<MemoryUseOrDef>(&*NextIt);
1100  MSSA->moveTo(MUD, To, MemorySSA::End);
1101  // Moving MUD from Accs in the moveTo above, may delete Accs, so we need to
1102  // retrieve it again.
1103  Accs = MSSA->getWritableBlockAccesses(From);
1104  MUD = NextMUD;
1105  } while (MUD);
1106 }
1107 
1109  BasicBlock *To,
1110  Instruction *Start) {
1111  assert(MSSA->getBlockAccesses(To) == nullptr &&
1112  "To block is expected to be free of MemoryAccesses.");
1113  moveAllAccesses(From, To, Start);
1114  for (BasicBlock *Succ : successors(To))
1115  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Succ))
1116  MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
1117 }
1118 
1120  Instruction *Start) {
1121  assert(From->getSinglePredecessor() == To &&
1122  "From block is expected to have a single predecessor (To).");
1123  moveAllAccesses(From, To, Start);
1124  for (BasicBlock *Succ : successors(From))
1125  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Succ))
1126  MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
1127 }
1128 
1129 /// If all arguments of a MemoryPHI are defined by the same incoming
1130 /// argument, return that argument.
1132  MemoryAccess *MA = nullptr;
1133 
1134  for (auto &Arg : MP->operands()) {
1135  if (!MA)
1136  MA = cast<MemoryAccess>(Arg);
1137  else if (MA != Arg)
1138  return nullptr;
1139  }
1140  return MA;
1141 }
1142 
1144  BasicBlock *Old, BasicBlock *New, ArrayRef<BasicBlock *> Preds,
1145  bool IdenticalEdgesWereMerged) {
1146  assert(!MSSA->getWritableBlockAccesses(New) &&
1147  "Access list should be null for a new block.");
1148  MemoryPhi *Phi = MSSA->getMemoryAccess(Old);
1149  if (!Phi)
1150  return;
1151  if (Old->hasNPredecessors(1)) {
1152  assert(pred_size(New) == Preds.size() &&
1153  "Should have moved all predecessors.");
1154  MSSA->moveTo(Phi, New, MemorySSA::Beginning);
1155  } else {
1156  assert(!Preds.empty() && "Must be moving at least one predecessor to the "
1157  "new immediate predecessor.");
1158  MemoryPhi *NewPhi = MSSA->createMemoryPhi(New);
1159  SmallPtrSet<BasicBlock *, 16> PredsSet(Preds.begin(), Preds.end());
1160  // Currently only support the case of removing a single incoming edge when
1161  // identical edges were not merged.
1162  if (!IdenticalEdgesWereMerged)
1163  assert(PredsSet.size() == Preds.size() &&
1164  "If identical edges were not merged, we cannot have duplicate "
1165  "blocks in the predecessors");
1166  Phi->unorderedDeleteIncomingIf([&](MemoryAccess *MA, BasicBlock *B) {
1167  if (PredsSet.count(B)) {
1168  NewPhi->addIncoming(MA, B);
1169  if (!IdenticalEdgesWereMerged)
1170  PredsSet.erase(B);
1171  return true;
1172  }
1173  return false;
1174  });
1175  Phi->addIncoming(NewPhi, New);
1176  if (onlySingleValue(NewPhi))
1177  removeMemoryAccess(NewPhi);
1178  }
1179 }
1180 
1182  assert(!MSSA->isLiveOnEntryDef(MA) &&
1183  "Trying to remove the live on entry def");
1184  // We can only delete phi nodes if they have no uses, or we can replace all
1185  // uses with a single definition.
1186  MemoryAccess *NewDefTarget = nullptr;
1187  if (MemoryPhi *MP = dyn_cast<MemoryPhi>(MA)) {
1188  // Note that it is sufficient to know that all edges of the phi node have
1189  // the same argument. If they do, by the definition of dominance frontiers
1190  // (which we used to place this phi), that argument must dominate this phi,
1191  // and thus, must dominate the phi's uses, and so we will not hit the assert
1192  // below.
1193  NewDefTarget = onlySingleValue(MP);
1194  assert((NewDefTarget || MP->use_empty()) &&
1195  "We can't delete this memory phi");
1196  } else {
1197  NewDefTarget = cast<MemoryUseOrDef>(MA)->getDefiningAccess();
1198  }
1199 
1200  SmallSetVector<MemoryPhi *, 4> PhisToCheck;
1201 
1202  // Re-point the uses at our defining access
1203  if (!isa<MemoryUse>(MA) && !MA->use_empty()) {
1204  // Reset optimized on users of this store, and reset the uses.
1205  // A few notes:
1206  // 1. This is a slightly modified version of RAUW to avoid walking the
1207  // uses twice here.
1208  // 2. If we wanted to be complete, we would have to reset the optimized
1209  // flags on users of phi nodes if doing the below makes a phi node have all
1210  // the same arguments. Instead, we prefer users to removeMemoryAccess those
1211  // phi nodes, because doing it here would be N^3.
1212  if (MA->hasValueHandle())
1213  ValueHandleBase::ValueIsRAUWd(MA, NewDefTarget);
1214  // Note: We assume MemorySSA is not used in metadata since it's not really
1215  // part of the IR.
1216 
1217  while (!MA->use_empty()) {
1218  Use &U = *MA->use_begin();
1219  if (auto *MUD = dyn_cast<MemoryUseOrDef>(U.getUser()))
1220  MUD->resetOptimized();
1221  if (OptimizePhis)
1222  if (MemoryPhi *MP = dyn_cast<MemoryPhi>(U.getUser()))
1223  PhisToCheck.insert(MP);
1224  U.set(NewDefTarget);
1225  }
1226  }
1227 
1228  // The call below to erase will destroy MA, so we can't change the order we
1229  // are doing things here
1230  MSSA->removeFromLookups(MA);
1231  MSSA->removeFromLists(MA);
1232 
1233  // Optionally optimize Phi uses. This will recursively remove trivial phis.
1234  if (!PhisToCheck.empty()) {
1235  SmallVector<WeakVH, 16> PhisToOptimize{PhisToCheck.begin(),
1236  PhisToCheck.end()};
1237  PhisToCheck.clear();
1238 
1239  unsigned PhisSize = PhisToOptimize.size();
1240  while (PhisSize-- > 0)
1241  if (MemoryPhi *MP =
1242  cast_or_null<MemoryPhi>(PhisToOptimize.pop_back_val())) {
1243  auto OperRange = MP->operands();
1244  tryRemoveTrivialPhi(MP, OperRange);
1245  }
1246  }
1247 }
1248 
1250  const SmallSetVector<BasicBlock *, 8> &DeadBlocks) {
1251  // First delete all uses of BB in MemoryPhis.
1252  for (BasicBlock *BB : DeadBlocks) {
1253  Instruction *TI = BB->getTerminator();
1254  assert(TI && "Basic block expected to have a terminator instruction");
1255  for (BasicBlock *Succ : successors(TI))
1256  if (!DeadBlocks.count(Succ))
1257  if (MemoryPhi *MP = MSSA->getMemoryAccess(Succ)) {
1258  MP->unorderedDeleteIncomingBlock(BB);
1259  if (MP->getNumIncomingValues() == 1)
1260  removeMemoryAccess(MP);
1261  }
1262  // Drop all references of all accesses in BB
1263  if (MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB))
1264  for (MemoryAccess &MA : *Acc)
1265  MA.dropAllReferences();
1266  }
1267 
1268  // Next, delete all memory accesses in each block
1269  for (BasicBlock *BB : DeadBlocks) {
1270  MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB);
1271  if (!Acc)
1272  continue;
1273  for (auto AB = Acc->begin(), AE = Acc->end(); AB != AE;) {
1274  MemoryAccess *MA = &*AB;
1275  ++AB;
1276  MSSA->removeFromLookups(MA);
1277  MSSA->removeFromLists(MA);
1278  }
1279  }
1280 }
1281 
1282 void MemorySSAUpdater::tryRemoveTrivialPhis(ArrayRef<WeakVH> UpdatedPHIs) {
1283  for (auto &VH : UpdatedPHIs)
1284  if (auto *MPhi = cast_or_null<MemoryPhi>(VH)) {
1285  auto OperRange = MPhi->operands();
1286  tryRemoveTrivialPhi(MPhi, OperRange);
1287  }
1288 }
1289 
1291  const BasicBlock *BB = I->getParent();
1292  // Remove memory accesses in BB for I and all following instructions.
1293  auto BBI = I->getIterator(), BBE = BB->end();
1294  // FIXME: If this becomes too expensive, iterate until the first instruction
1295  // with a memory access, then iterate over MemoryAccesses.
1296  while (BBI != BBE)
1297  removeMemoryAccess(&*(BBI++));
1298  // Update phis in BB's successors to remove BB.
1299  SmallVector<WeakVH, 16> UpdatedPHIs;
1300  for (const BasicBlock *Successor : successors(BB)) {
1302  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Successor)) {
1303  MPhi->unorderedDeleteIncomingBlock(BB);
1304  UpdatedPHIs.push_back(MPhi);
1305  }
1306  }
1307  // Optimize trivial phis.
1308  tryRemoveTrivialPhis(UpdatedPHIs);
1309 }
1310 
1312  const BasicBlock *To) {
1313  const BasicBlock *BB = BI->getParent();
1314  SmallVector<WeakVH, 16> UpdatedPHIs;
1315  for (const BasicBlock *Succ : successors(BB)) {
1317  if (Succ != To)
1318  if (auto *MPhi = MSSA->getMemoryAccess(Succ)) {
1319  MPhi->unorderedDeleteIncomingBlock(BB);
1320  UpdatedPHIs.push_back(MPhi);
1321  }
1322  }
1323  // Optimize trivial phis.
1324  tryRemoveTrivialPhis(UpdatedPHIs);
1325 }
1326 
1328  Instruction *I, MemoryAccess *Definition, const BasicBlock *BB,
1329  MemorySSA::InsertionPlace Point) {
1330  MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1331  MSSA->insertIntoListsForBlock(NewAccess, BB, Point);
1332  return NewAccess;
1333 }
1334 
1336  Instruction *I, MemoryAccess *Definition, MemoryUseOrDef *InsertPt) {
1337  assert(I->getParent() == InsertPt->getBlock() &&
1338  "New and old access must be in the same block");
1339  MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1340  MSSA->insertIntoListsBefore(NewAccess, InsertPt->getBlock(),
1341  InsertPt->getIterator());
1342  return NewAccess;
1343 }
1344 
1346  Instruction *I, MemoryAccess *Definition, MemoryAccess *InsertPt) {
1347  assert(I->getParent() == InsertPt->getBlock() &&
1348  "New and old access must be in the same block");
1349  MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1350  MSSA->insertIntoListsBefore(NewAccess, InsertPt->getBlock(),
1351  ++InsertPt->getIterator());
1352  return NewAccess;
1353 }
use_iterator use_end()
Definition: Value.h:346
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:233
AccessList * getWritableBlockAccesses(const BasicBlock *BB) const
Definition: MemorySSA.h:802
bool hasNPredecessors(unsigned N) const
Return true if this block has exactly N predecessors.
Definition: BasicBlock.cpp:260
static MemoryAccess * onlySingleValue(MemoryPhi *MP)
If all arguments of a MemoryPHI are defined by the same incoming argument, return that argument...
const_iterator begin(StringRef path, Style style=Style::native)
Get begin iterator over path.
Definition: Path.cpp:224
void dropAllReferences()
Drop all references to operands.
Definition: User.h:294
This class represents lattice values for constants.
Definition: AllocatorList.h:23
AllAccessType::self_iterator getIterator()
Get the iterators for the all access list and the defs only list We default to the all access list...
Definition: MemorySSA.h:178
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
MemoryAccess * getDefiningAccess() const
Get the access that produces the memory state used by this Use.
Definition: MemorySSA.h:257
void updateExitBlocksForClonedLoop(ArrayRef< BasicBlock *> ExitBlocks, const ValueToValueMapTy &VMap, DominatorTree &DT)
Update phi nodes in exit block successors following cloning.
iterator begin() const
Definition: ArrayRef.h:136
BasicBlock * getSuccessor(unsigned Idx) const
Return the specified successor. This instruction must be a terminator.
void applyInsertUpdates(ArrayRef< CFGUpdate > Updates, DominatorTree &DT)
Apply CFG insert updates, analogous with the DT edge updates.
const AccessList * getBlockAccesses(const BasicBlock *BB) const
Return the list of MemoryAccess&#39;s for a given basic block.
Definition: MemorySSA.h:758
void changeToUnreachable(const Instruction *I)
Instruction I will be changed to an unreachable.
This file contains the declarations for metadata subclasses.
bool hasValueHandle() const
Return true if there is a value handle associated with this value.
Definition: Value.h:485
void moveAfter(MemoryUseOrDef *What, MemoryUseOrDef *Where)
Represents a read-write access to memory, whether it is a must-alias, or a may-alias.
Definition: MemorySSA.h:375
NodeT * findNearestCommonDominator(NodeT *A, NodeT *B) const
findNearestCommonDominator - Find nearest common dominator basic block for basic block A and B...
void insertUse(MemoryUse *Use)
int getBasicBlockIndex(const BasicBlock *BB) const
Return the first index of the specified basic block in the value list for this PHI.
Definition: MemorySSA.h:575
reverse_iterator rbegin()
Definition: BasicBlock.h:273
const Instruction * getTerminator() const LLVM_READONLY
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:137
DefsOnlyType::self_iterator getDefsIterator()
Definition: MemorySSA.h:190
void calculate(SmallVectorImpl< NodeTy *> &IDFBlocks)
Calculate iterated dominance frontiers.
iterator end()
Get an iterator to the end of the SetVector.
Definition: SetVector.h:92
bool isReachableFromEntry(const Use &U) const
Provide an overload for a Use.
Definition: Dominators.cpp:299
op_iterator op_begin()
Definition: User.h:229
void setIncomingValue(unsigned I, MemoryAccess *V)
Definition: MemorySSA.h:534
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:268
Represents read-only accesses to memory.
Definition: MemorySSA.h:319
void removeEdge(BasicBlock *From, BasicBlock *To)
Update the MemoryPhi in To following an edge deletion between From and To.
void renamePass(BasicBlock *BB, MemoryAccess *IncomingVal, SmallPtrSetImpl< BasicBlock *> &Visited)
Definition: MemorySSA.h:821
block_iterator block_begin()
Definition: MemorySSA.h:500
A Use represents the edge between a Value definition and its users.
Definition: Use.h:55
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:41
void applyUpdates(ArrayRef< CFGUpdate > Updates, DominatorTree &DT)
Apply CFG updates, analogous with the DT edge updates.
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
A simple intrusive list implementation.
Definition: simple_ilist.h:78
User * getUser() const LLVM_READONLY
Returns the User that contains this Use.
Definition: Use.cpp:40
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:141
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
iterator begin()
Get an iterator to the beginning of the SetVector.
Definition: SetVector.h:82
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:429
ValueT lookup(const KeyT &Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: ValueMap.h:170
static void ValueIsRAUWd(Value *Old, Value *New)
Definition: Value.cpp:912
static bool ProcessBlock(BasicBlock &BB, DominatorTree &DT, LoopInfo &LI, AAResults &AA)
Definition: Sink.cpp:198
MemoryUseOrDef * createMemoryAccessBefore(Instruction *I, MemoryAccess *Definition, MemoryUseOrDef *InsertPt)
Create a MemoryAccess in MemorySSA before or after an existing MemoryAccess.
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
size_type count(const key_type &key) const
Count the number of elements of a given key in the SetVector.
Definition: SetVector.h:210
MemoryAccess * getIncomingValue(unsigned I) const
Return incoming value number x.
Definition: MemorySSA.h:533
use_iterator_impl< Use > use_iterator
Definition: Value.h:331
NodeT * getBlock() const
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
const BasicBlock * getSinglePredecessor() const
Return the predecessor of this block if it has a single predecessor block.
Definition: BasicBlock.cpp:233
static constexpr UpdateKind Insert
void updatePhisWhenInsertingUniqueBackedgeBlock(BasicBlock *LoopHeader, BasicBlock *LoopPreheader, BasicBlock *BackedgeBlock)
Update MemorySSA when inserting a unique backedge block for a loop.
void set(Value *Val)
Definition: Value.h:710
AllAccessType::reverse_self_iterator getReverseIterator()
Definition: MemorySSA.h:184
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
static void setMemoryPhiValueForBlock(MemoryPhi *MP, const BasicBlock *BB, MemoryAccess *NewDef)
Conditional or Unconditional Branch instruction.
Value handle that tracks a Value across RAUW.
Definition: ValueHandle.h:327
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:148
DomTreeNodeBase * getIDom() const
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
void removeDuplicatePhiEdgesBetween(const BasicBlock *From, const BasicBlock *To)
Update the MemoryPhi in To to have a single incoming edge from From, following a CFG change that repl...
void addIncoming(MemoryAccess *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
Definition: MemorySSA.h:564
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
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
void moveAllAfterSpliceBlocks(BasicBlock *From, BasicBlock *To, Instruction *Start)
From block was spliced into From and To.
op_iterator op_end()
Definition: User.h:231
amdgpu Simplify well known AMD library false FunctionCallee Value * Arg
Interval::pred_iterator pred_end(Interval *I)
Definition: Interval.h:115
op_range operands()
Definition: User.h:237
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:381
self_iterator getIterator()
Definition: ilist_node.h:81
void updateForClonedLoop(const LoopBlocksRPO &LoopBlocks, ArrayRef< BasicBlock *> ExitBlocks, const ValueToValueMapTy &VM, bool IgnoreIncomingWithNoClones=false)
Update MemorySSA after a loop was cloned, given the blocks in RPO order, the exit blocks and a 1:1 ma...
MemoryAccess * createMemoryAccessInBB(Instruction *I, MemoryAccess *Definition, const BasicBlock *BB, MemorySSA::InsertionPlace Point)
Create a MemoryAccess in MemorySSA at a specified point in a block, with a specified clobbering defin...
DomTreeNodeBase< NodeT > * getNode(const NodeT *BB) const
getNode - return the (Post)DominatorTree node for the specified basic block.
An intrusive list with ownership and callbacks specified/controlled by ilist_traits, only with API safe for polymorphic types.
Definition: ilist.h:388
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
void moveToPlace(MemoryUseOrDef *What, BasicBlock *BB, MemorySSA::InsertionPlace Where)
MemoryUseOrDef * createDefinedAccess(Instruction *, MemoryAccess *, const MemoryUseOrDef *Template=nullptr)
Definition: MemorySSA.cpp:1688
void setDefiningBlocks(const SmallPtrSetImpl< NodeTy *> &Blocks)
Give the IDF calculator the set of blocks in which the value is defined.
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:297
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
iterator end()
Definition: BasicBlock.h:270
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
Module.h This file contains the declarations for the Module class.
iterator end() const
Definition: ArrayRef.h:137
void wireOldPredecessorsToNewImmediatePredecessor(BasicBlock *Old, BasicBlock *New, ArrayRef< BasicBlock *> Preds, bool IdenticalEdgesWereMerged=true)
A new empty BasicBlock (New) now branches directly to Old.
BasicBlock * getBlock() const
Definition: MemorySSA.h:159
pred_range predecessors(BasicBlock *BB)
Definition: CFG.h:124
MemoryAccess * getLiveOnEntryDef() const
Definition: MemorySSA.h:742
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
Class that has the common methods + fields of memory uses/defs.
Definition: MemorySSA.h:247
iterator_range< user_iterator > users()
Definition: Value.h:399
unsigned getNumIncomingValues() const
Return the number of incoming edges.
Definition: MemorySSA.h:530
BasicBlock * getIncomingBlock(unsigned I) const
Return incoming basic block number i.
Definition: MemorySSA.h:543
use_iterator use_begin()
Definition: Value.h:338
block_iterator block_end()
Definition: MemorySSA.h:511
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:55
unsigned pred_size(const BasicBlock *BB)
Get the number of predecessors of BB.
Definition: CFG.h:121
#define I(x, y, z)
Definition: MD5.cpp:58
bool empty() const
Determine if the SetVector is empty or not.
Definition: SetVector.h:72
MemoryUseOrDef * createMemoryAccessAfter(Instruction *I, MemoryAccess *Definition, MemoryAccess *InsertPt)
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
void moveAllAfterMergeBlocks(BasicBlock *From, BasicBlock *To, Instruction *Start)
From block was merged into To.
bool isLiveOnEntryDef(const MemoryAccess *MA) const
Return true if MA represents the live on entry value.
Definition: MemorySSA.h:738
reverse_iterator rend(StringRef path)
Get reverse end iterator over path.
Definition: Path.cpp:304
ValueT lookup(const_arg_type_t< KeyT > Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: DenseMap.h:211
iterator insert(iterator I, reference Node)
Insert a node by reference; never copies.
Definition: simple_ilist.h:159
Wrapper class to LoopBlocksDFS that provides a standard begin()/end() interface for the DFS reverse p...
Definition: LoopIterator.h:172
void removeMemoryAccess(MemoryAccess *, bool OptimizePhis=false)
Remove a MemoryAccess from MemorySSA, including updating all definitions and uses.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
void removeBlocks(const SmallSetVector< BasicBlock *, 8 > &DeadBlocks)
Remove all MemoryAcceses in a set of BasicBlocks about to be deleted.
user_iterator user_begin()
Definition: Value.h:375
void insertDef(MemoryDef *Def, bool RenameUses=false)
Insert a definition into the MemorySSA IR.
succ_range successors(Instruction *I)
Definition: CFG.h:259
DefsOnlyType::reverse_self_iterator getReverseDefsIterator()
Definition: MemorySSA.h:196
This file exposes an interface to building/using memory SSA to walk memory instructions using a use/d...
Represents phi nodes for memory accesses.
Definition: MemorySSA.h:481
DefsList * getWritableBlockDefs(const BasicBlock *BB) const
Definition: MemorySSA.h:808
#define LLVM_DEBUG(X)
Definition: Debug.h:122
OutputIt copy(R &&Range, OutputIt Out)
Definition: STLExtras.h:1244
void moveBefore(MemoryUseOrDef *What, MemoryUseOrDef *Where)
void updateForClonedBlockIntoPred(BasicBlock *BB, BasicBlock *P1, const ValueToValueMapTy &VM)
bool use_empty() const
Definition: Value.h:322
void changeCondBranchToUnconditionalTo(const BranchInst *BI, const BasicBlock *To)
Conditional branch BI is changed or replaced with an unconditional branch to To.
bool empty() const
empty - Check if the array is empty.
Definition: ArrayRef.h:143
const BasicBlock * getParent() const
Definition: Instruction.h:66
user_iterator user_end()
Definition: Value.h:383