LLVM  10.0.0svn
MemorySSAUpdater.cpp
Go to the documentation of this file.
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  tryRemoveTrivialPhi(UsePhi);
179  return Res;
180 }
181 
182 // Eliminate trivial phis
183 // Phis are trivial if they are defined either by themselves, or all the same
184 // argument.
185 // IE phi(a, a) or b = phi(a, b) or c = phi(a, a, c)
186 // We recursively try to remove them.
187 MemoryAccess *MemorySSAUpdater::tryRemoveTrivialPhi(MemoryPhi *Phi) {
188  assert(Phi && "Can only remove concrete Phi.");
189  auto OperRange = Phi->operands();
190  return tryRemoveTrivialPhi(Phi, OperRange);
191 }
192 template <class RangeType>
193 MemoryAccess *MemorySSAUpdater::tryRemoveTrivialPhi(MemoryPhi *Phi,
194  RangeType &Operands) {
195  // Bail out on non-opt Phis.
196  if (NonOptPhis.count(Phi))
197  return Phi;
198 
199  // Detect equal or self arguments
200  MemoryAccess *Same = nullptr;
201  for (auto &Op : Operands) {
202  // If the same or self, good so far
203  if (Op == Phi || Op == Same)
204  continue;
205  // not the same, return the phi since it's not eliminatable by us
206  if (Same)
207  return Phi;
208  Same = cast<MemoryAccess>(&*Op);
209  }
210  // Never found a non-self reference, the phi is undef
211  if (Same == nullptr)
212  return MSSA->getLiveOnEntryDef();
213  if (Phi) {
214  Phi->replaceAllUsesWith(Same);
215  removeMemoryAccess(Phi);
216  }
217 
218  // We should only end up recursing in case we replaced something, in which
219  // case, we may have made other Phis trivial.
220  return recursePhi(Same);
221 }
222 
223 void MemorySSAUpdater::insertUse(MemoryUse *MU, bool RenameUses) {
224  InsertedPHIs.clear();
225  MU->setDefiningAccess(getPreviousDef(MU));
226  // In cases without unreachable blocks, because uses do not create new
227  // may-defs, there are only two cases:
228  // 1. There was a def already below us, and therefore, we should not have
229  // created a phi node because it was already needed for the def.
230  //
231  // 2. There is no def below us, and therefore, there is no extra renaming work
232  // to do.
233 
234  // In cases with unreachable blocks, where the unnecessary Phis were
235  // optimized out, adding the Use may re-insert those Phis. Hence, when
236  // inserting Uses outside of the MSSA creation process, and new Phis were
237  // added, rename all uses if we are asked.
238 
239  if (!RenameUses && !InsertedPHIs.empty()) {
240  auto *Defs = MSSA->getBlockDefs(MU->getBlock());
241  (void)Defs;
242  assert((!Defs || (++Defs->begin() == Defs->end())) &&
243  "Block may have only a Phi or no defs");
244  }
245 
246  if (RenameUses && InsertedPHIs.size()) {
248  BasicBlock *StartBlock = MU->getBlock();
249 
250  if (auto *Defs = MSSA->getWritableBlockDefs(StartBlock)) {
251  MemoryAccess *FirstDef = &*Defs->begin();
252  // Convert to incoming value if it's a memorydef. A phi *is* already an
253  // incoming value.
254  if (auto *MD = dyn_cast<MemoryDef>(FirstDef))
255  FirstDef = MD->getDefiningAccess();
256 
257  MSSA->renamePass(MU->getBlock(), FirstDef, Visited);
258  // We just inserted a phi into this block, so the incoming value will
259  // become the phi anyway, so it does not matter what we pass.
260  for (auto &MP : InsertedPHIs)
261  if (MemoryPhi *Phi = cast_or_null<MemoryPhi>(MP))
262  MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
263  }
264  }
265 }
266 
267 // Set every incoming edge {BB, MP->getBlock()} of MemoryPhi MP to NewDef.
268 static void setMemoryPhiValueForBlock(MemoryPhi *MP, const BasicBlock *BB,
269  MemoryAccess *NewDef) {
270  // Replace any operand with us an incoming block with the new defining
271  // access.
272  int i = MP->getBasicBlockIndex(BB);
273  assert(i != -1 && "Should have found the basic block in the phi");
274  // We can't just compare i against getNumOperands since one is signed and the
275  // other not. So use it to index into the block iterator.
276  for (auto BBIter = MP->block_begin() + i; BBIter != MP->block_end();
277  ++BBIter) {
278  if (*BBIter != BB)
279  break;
280  MP->setIncomingValue(i, NewDef);
281  ++i;
282  }
283 }
284 
285 // A brief description of the algorithm:
286 // First, we compute what should define the new def, using the SSA
287 // construction algorithm.
288 // Then, we update the defs below us (and any new phi nodes) in the graph to
289 // point to the correct new defs, to ensure we only have one variable, and no
290 // disconnected stores.
291 void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
292  InsertedPHIs.clear();
293 
294  // See if we had a local def, and if not, go hunting.
295  MemoryAccess *DefBefore = getPreviousDef(MD);
296  bool DefBeforeSameBlock = DefBefore->getBlock() == MD->getBlock();
297 
298  // There is a def before us, which means we can replace any store/phi uses
299  // of that thing with us, since we are in the way of whatever was there
300  // before.
301  // We now define that def's memorydefs and memoryphis
302  if (DefBeforeSameBlock) {
303  DefBefore->replaceUsesWithIf(MD, [MD](Use &U) {
304  // Leave the MemoryUses alone.
305  // Also make sure we skip ourselves to avoid self references.
306  User *Usr = U.getUser();
307  return !isa<MemoryUse>(Usr) && Usr != MD;
308  // Defs are automatically unoptimized when the user is set to MD below,
309  // because the isOptimized() call will fail to find the same ID.
310  });
311  }
312 
313  // and that def is now our defining access.
314  MD->setDefiningAccess(DefBefore);
315 
316  // Remember the index where we may insert new phis below.
317  unsigned NewPhiIndex = InsertedPHIs.size();
318 
319  SmallVector<WeakVH, 8> FixupList(InsertedPHIs.begin(), InsertedPHIs.end());
320  if (!DefBeforeSameBlock) {
321  // If there was a local def before us, we must have the same effect it
322  // did. Because every may-def is the same, any phis/etc we would create, it
323  // would also have created. If there was no local def before us, we
324  // performed a global update, and have to search all successors and make
325  // sure we update the first def in each of them (following all paths until
326  // we hit the first def along each path). This may also insert phi nodes.
327  // TODO: There are other cases we can skip this work, such as when we have a
328  // single successor, and only used a straight line of single pred blocks
329  // backwards to find the def. To make that work, we'd have to track whether
330  // getDefRecursive only ever used the single predecessor case. These types
331  // of paths also only exist in between CFG simplifications.
332 
333  // If this is the first def in the block and this insert is in an arbitrary
334  // place, compute IDF and place phis.
335  auto Iter = MD->getDefsIterator();
336  ++Iter;
337  auto IterEnd = MSSA->getBlockDefs(MD->getBlock())->end();
338  if (Iter == IterEnd) {
339  ForwardIDFCalculator IDFs(*MSSA->DT);
341  SmallPtrSet<BasicBlock *, 2> DefiningBlocks;
342  DefiningBlocks.insert(MD->getBlock());
343  IDFs.setDefiningBlocks(DefiningBlocks);
344  IDFs.calculate(IDFBlocks);
345  SmallVector<AssertingVH<MemoryPhi>, 4> NewInsertedPHIs;
346  for (auto *BBIDF : IDFBlocks) {
347  auto *MPhi = MSSA->getMemoryAccess(BBIDF);
348  if (!MPhi) {
349  MPhi = MSSA->createMemoryPhi(BBIDF);
350  NewInsertedPHIs.push_back(MPhi);
351  }
352  // Add the phis created into the IDF blocks to NonOptPhis, so they are
353  // not optimized out as trivial by the call to getPreviousDefFromEnd
354  // below. Once they are complete, all these Phis are added to the
355  // FixupList, and removed from NonOptPhis inside fixupDefs().
356  // Existing Phis in IDF may need fixing as well, and potentially be
357  // trivial before this insertion, hence add all IDF Phis. See PR43044.
358  NonOptPhis.insert(MPhi);
359  }
360 
361  for (auto &MPhi : NewInsertedPHIs) {
362  auto *BBIDF = MPhi->getBlock();
363  for (auto *Pred : predecessors(BBIDF)) {
365  MPhi->addIncoming(getPreviousDefFromEnd(Pred, CachedPreviousDef),
366  Pred);
367  }
368  }
369 
370  // Re-take the index where we're adding the new phis, because the above
371  // call to getPreviousDefFromEnd, may have inserted into InsertedPHIs.
372  NewPhiIndex = InsertedPHIs.size();
373  for (auto &MPhi : NewInsertedPHIs) {
374  InsertedPHIs.push_back(&*MPhi);
375  FixupList.push_back(&*MPhi);
376  }
377  }
378 
379  FixupList.push_back(MD);
380  }
381 
382  // Remember the index where we stopped inserting new phis above, since the
383  // fixupDefs call in the loop below may insert more, that are already minimal.
384  unsigned NewPhiIndexEnd = InsertedPHIs.size();
385 
386  while (!FixupList.empty()) {
387  unsigned StartingPHISize = InsertedPHIs.size();
388  fixupDefs(FixupList);
389  FixupList.clear();
390  // Put any new phis on the fixup list, and process them
391  FixupList.append(InsertedPHIs.begin() + StartingPHISize, InsertedPHIs.end());
392  }
393 
394  // Optimize potentially non-minimal phis added in this method.
395  unsigned NewPhiSize = NewPhiIndexEnd - NewPhiIndex;
396  if (NewPhiSize)
397  tryRemoveTrivialPhis(ArrayRef<WeakVH>(&InsertedPHIs[NewPhiIndex], NewPhiSize));
398 
399  // Now that all fixups are done, rename all uses if we are asked.
400  if (RenameUses) {
402  BasicBlock *StartBlock = MD->getBlock();
403  // We are guaranteed there is a def in the block, because we just got it
404  // handed to us in this function.
405  MemoryAccess *FirstDef = &*MSSA->getWritableBlockDefs(StartBlock)->begin();
406  // Convert to incoming value if it's a memorydef. A phi *is* already an
407  // incoming value.
408  if (auto *MD = dyn_cast<MemoryDef>(FirstDef))
409  FirstDef = MD->getDefiningAccess();
410 
411  MSSA->renamePass(MD->getBlock(), FirstDef, Visited);
412  // We just inserted a phi into this block, so the incoming value will become
413  // the phi anyway, so it does not matter what we pass.
414  for (auto &MP : InsertedPHIs) {
415  MemoryPhi *Phi = dyn_cast_or_null<MemoryPhi>(MP);
416  if (Phi)
417  MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
418  }
419  }
420 }
421 
422 void MemorySSAUpdater::fixupDefs(const SmallVectorImpl<WeakVH> &Vars) {
425  for (auto &Var : Vars) {
426  MemoryAccess *NewDef = dyn_cast_or_null<MemoryAccess>(Var);
427  if (!NewDef)
428  continue;
429  // First, see if there is a local def after the operand.
430  auto *Defs = MSSA->getWritableBlockDefs(NewDef->getBlock());
431  auto DefIter = NewDef->getDefsIterator();
432 
433  // The temporary Phi is being fixed, unmark it for not to optimize.
434  if (MemoryPhi *Phi = dyn_cast<MemoryPhi>(NewDef))
435  NonOptPhis.erase(Phi);
436 
437  // If there is a local def after us, we only have to rename that.
438  if (++DefIter != Defs->end()) {
439  cast<MemoryDef>(DefIter)->setDefiningAccess(NewDef);
440  continue;
441  }
442 
443  // Otherwise, we need to search down through the CFG.
444  // For each of our successors, handle it directly if their is a phi, or
445  // place on the fixup worklist.
446  for (const auto *S : successors(NewDef->getBlock())) {
447  if (auto *MP = MSSA->getMemoryAccess(S))
448  setMemoryPhiValueForBlock(MP, NewDef->getBlock(), NewDef);
449  else
450  Worklist.push_back(S);
451  }
452 
453  while (!Worklist.empty()) {
454  const BasicBlock *FixupBlock = Worklist.back();
455  Worklist.pop_back();
456 
457  // Get the first def in the block that isn't a phi node.
458  if (auto *Defs = MSSA->getWritableBlockDefs(FixupBlock)) {
459  auto *FirstDef = &*Defs->begin();
460  // The loop above and below should have taken care of phi nodes
461  assert(!isa<MemoryPhi>(FirstDef) &&
462  "Should have already handled phi nodes!");
463  // We are now this def's defining access, make sure we actually dominate
464  // it
465  assert(MSSA->dominates(NewDef, FirstDef) &&
466  "Should have dominated the new access");
467 
468  // This may insert new phi nodes, because we are not guaranteed the
469  // block we are processing has a single pred, and depending where the
470  // store was inserted, it may require phi nodes below it.
471  cast<MemoryDef>(FirstDef)->setDefiningAccess(getPreviousDef(FirstDef));
472  return;
473  }
474  // We didn't find a def, so we must continue.
475  for (const auto *S : successors(FixupBlock)) {
476  // If there is a phi node, handle it.
477  // Otherwise, put the block on the worklist
478  if (auto *MP = MSSA->getMemoryAccess(S))
479  setMemoryPhiValueForBlock(MP, FixupBlock, NewDef);
480  else {
481  // If we cycle, we should have ended up at a phi node that we already
482  // processed. FIXME: Double check this
483  if (!Seen.insert(S).second)
484  continue;
485  Worklist.push_back(S);
486  }
487  }
488  }
489  }
490 }
491 
493  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(To)) {
494  MPhi->unorderedDeleteIncomingBlock(From);
495  tryRemoveTrivialPhi(MPhi);
496  }
497 }
498 
500  const BasicBlock *To) {
501  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(To)) {
502  bool Found = false;
503  MPhi->unorderedDeleteIncomingIf([&](const MemoryAccess *, BasicBlock *B) {
504  if (From != B)
505  return false;
506  if (Found)
507  return true;
508  Found = true;
509  return false;
510  });
511  tryRemoveTrivialPhi(MPhi);
512  }
513 }
514 
516  const ValueToValueMapTy &VMap,
517  PhiToDefMap &MPhiMap,
518  bool CloneWasSimplified,
519  MemorySSA *MSSA) {
520  MemoryAccess *InsnDefining = MA;
521  if (MemoryDef *DefMUD = dyn_cast<MemoryDef>(InsnDefining)) {
522  if (!MSSA->isLiveOnEntryDef(DefMUD)) {
523  Instruction *DefMUDI = DefMUD->getMemoryInst();
524  assert(DefMUDI && "Found MemoryUseOrDef with no Instruction.");
525  if (Instruction *NewDefMUDI =
526  cast_or_null<Instruction>(VMap.lookup(DefMUDI))) {
527  InsnDefining = MSSA->getMemoryAccess(NewDefMUDI);
528  if (!CloneWasSimplified)
529  assert(InsnDefining && "Defining instruction cannot be nullptr.");
530  else if (!InsnDefining || isa<MemoryUse>(InsnDefining)) {
531  // The clone was simplified, it's no longer a MemoryDef, look up.
532  auto DefIt = DefMUD->getDefsIterator();
533  // Since simplified clones only occur in single block cloning, a
534  // previous definition must exist, otherwise NewDefMUDI would not
535  // have been found in VMap.
536  assert(DefIt != MSSA->getBlockDefs(DefMUD->getBlock())->begin() &&
537  "Previous def must exist");
538  InsnDefining = getNewDefiningAccessForClone(
539  &*(--DefIt), VMap, MPhiMap, CloneWasSimplified, MSSA);
540  }
541  }
542  }
543  } else {
544  MemoryPhi *DefPhi = cast<MemoryPhi>(InsnDefining);
545  if (MemoryAccess *NewDefPhi = MPhiMap.lookup(DefPhi))
546  InsnDefining = NewDefPhi;
547  }
548  assert(InsnDefining && "Defining instruction cannot be nullptr.");
549  return InsnDefining;
550 }
551 
552 void MemorySSAUpdater::cloneUsesAndDefs(BasicBlock *BB, BasicBlock *NewBB,
553  const ValueToValueMapTy &VMap,
554  PhiToDefMap &MPhiMap,
555  bool CloneWasSimplified) {
556  const MemorySSA::AccessList *Acc = MSSA->getBlockAccesses(BB);
557  if (!Acc)
558  return;
559  for (const MemoryAccess &MA : *Acc) {
560  if (const MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&MA)) {
561  Instruction *Insn = MUD->getMemoryInst();
562  // Entry does not exist if the clone of the block did not clone all
563  // instructions. This occurs in LoopRotate when cloning instructions
564  // from the old header to the old preheader. The cloned instruction may
565  // also be a simplified Value, not an Instruction (see LoopRotate).
566  // Also in LoopRotate, even when it's an instruction, due to it being
567  // simplified, it may be a Use rather than a Def, so we cannot use MUD as
568  // template. Calls coming from updateForClonedBlockIntoPred, ensure this.
569  if (Instruction *NewInsn =
570  dyn_cast_or_null<Instruction>(VMap.lookup(Insn))) {
571  MemoryAccess *NewUseOrDef = MSSA->createDefinedAccess(
572  NewInsn,
573  getNewDefiningAccessForClone(MUD->getDefiningAccess(), VMap,
574  MPhiMap, CloneWasSimplified, MSSA),
575  /*Template=*/CloneWasSimplified ? nullptr : MUD,
576  /*CreationMustSucceed=*/CloneWasSimplified ? false : true);
577  if (NewUseOrDef)
578  MSSA->insertIntoListsForBlock(NewUseOrDef, NewBB, MemorySSA::End);
579  }
580  }
581  }
582 }
583 
585  BasicBlock *Header, BasicBlock *Preheader, BasicBlock *BEBlock) {
586  auto *MPhi = MSSA->getMemoryAccess(Header);
587  if (!MPhi)
588  return;
589 
590  // Create phi node in the backedge block and populate it with the same
591  // incoming values as MPhi. Skip incoming values coming from Preheader.
592  auto *NewMPhi = MSSA->createMemoryPhi(BEBlock);
593  bool HasUniqueIncomingValue = true;
594  MemoryAccess *UniqueValue = nullptr;
595  for (unsigned I = 0, E = MPhi->getNumIncomingValues(); I != E; ++I) {
596  BasicBlock *IBB = MPhi->getIncomingBlock(I);
597  MemoryAccess *IV = MPhi->getIncomingValue(I);
598  if (IBB != Preheader) {
599  NewMPhi->addIncoming(IV, IBB);
600  if (HasUniqueIncomingValue) {
601  if (!UniqueValue)
602  UniqueValue = IV;
603  else if (UniqueValue != IV)
604  HasUniqueIncomingValue = false;
605  }
606  }
607  }
608 
609  // Update incoming edges into MPhi. Remove all but the incoming edge from
610  // Preheader. Add an edge from NewMPhi
611  auto *AccFromPreheader = MPhi->getIncomingValueForBlock(Preheader);
612  MPhi->setIncomingValue(0, AccFromPreheader);
613  MPhi->setIncomingBlock(0, Preheader);
614  for (unsigned I = MPhi->getNumIncomingValues() - 1; I >= 1; --I)
615  MPhi->unorderedDeleteIncoming(I);
616  MPhi->addIncoming(NewMPhi, BEBlock);
617 
618  // If NewMPhi is a trivial phi, remove it. Its use in the header MPhi will be
619  // replaced with the unique value.
620  tryRemoveTrivialPhi(MPhi);
621 }
622 
624  ArrayRef<BasicBlock *> ExitBlocks,
625  const ValueToValueMapTy &VMap,
626  bool IgnoreIncomingWithNoClones) {
627  PhiToDefMap MPhiMap;
628 
629  auto FixPhiIncomingValues = [&](MemoryPhi *Phi, MemoryPhi *NewPhi) {
630  assert(Phi && NewPhi && "Invalid Phi nodes.");
631  BasicBlock *NewPhiBB = NewPhi->getBlock();
632  SmallPtrSet<BasicBlock *, 4> NewPhiBBPreds(pred_begin(NewPhiBB),
633  pred_end(NewPhiBB));
634  for (unsigned It = 0, E = Phi->getNumIncomingValues(); It < E; ++It) {
635  MemoryAccess *IncomingAccess = Phi->getIncomingValue(It);
636  BasicBlock *IncBB = Phi->getIncomingBlock(It);
637 
638  if (BasicBlock *NewIncBB = cast_or_null<BasicBlock>(VMap.lookup(IncBB)))
639  IncBB = NewIncBB;
640  else if (IgnoreIncomingWithNoClones)
641  continue;
642 
643  // Now we have IncBB, and will need to add incoming from it to NewPhi.
644 
645  // If IncBB is not a predecessor of NewPhiBB, then do not add it.
646  // NewPhiBB was cloned without that edge.
647  if (!NewPhiBBPreds.count(IncBB))
648  continue;
649 
650  // Determine incoming value and add it as incoming from IncBB.
651  if (MemoryUseOrDef *IncMUD = dyn_cast<MemoryUseOrDef>(IncomingAccess)) {
652  if (!MSSA->isLiveOnEntryDef(IncMUD)) {
653  Instruction *IncI = IncMUD->getMemoryInst();
654  assert(IncI && "Found MemoryUseOrDef with no Instruction.");
655  if (Instruction *NewIncI =
656  cast_or_null<Instruction>(VMap.lookup(IncI))) {
657  IncMUD = MSSA->getMemoryAccess(NewIncI);
658  assert(IncMUD &&
659  "MemoryUseOrDef cannot be null, all preds processed.");
660  }
661  }
662  NewPhi->addIncoming(IncMUD, IncBB);
663  } else {
664  MemoryPhi *IncPhi = cast<MemoryPhi>(IncomingAccess);
665  if (MemoryAccess *NewDefPhi = MPhiMap.lookup(IncPhi))
666  NewPhi->addIncoming(NewDefPhi, IncBB);
667  else
668  NewPhi->addIncoming(IncPhi, IncBB);
669  }
670  }
671  };
672 
673  auto ProcessBlock = [&](BasicBlock *BB) {
674  BasicBlock *NewBlock = cast_or_null<BasicBlock>(VMap.lookup(BB));
675  if (!NewBlock)
676  return;
677 
678  assert(!MSSA->getWritableBlockAccesses(NewBlock) &&
679  "Cloned block should have no accesses");
680 
681  // Add MemoryPhi.
682  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB)) {
683  MemoryPhi *NewPhi = MSSA->createMemoryPhi(NewBlock);
684  MPhiMap[MPhi] = NewPhi;
685  }
686  // Update Uses and Defs.
687  cloneUsesAndDefs(BB, NewBlock, VMap, MPhiMap);
688  };
689 
690  for (auto BB : llvm::concat<BasicBlock *const>(LoopBlocks, ExitBlocks))
691  ProcessBlock(BB);
692 
693  for (auto BB : llvm::concat<BasicBlock *const>(LoopBlocks, ExitBlocks))
694  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB))
695  if (MemoryAccess *NewPhi = MPhiMap.lookup(MPhi))
696  FixPhiIncomingValues(MPhi, cast<MemoryPhi>(NewPhi));
697 }
698 
700  BasicBlock *BB, BasicBlock *P1, const ValueToValueMapTy &VM) {
701  // All defs/phis from outside BB that are used in BB, are valid uses in P1.
702  // Since those defs/phis must have dominated BB, and also dominate P1.
703  // Defs from BB being used in BB will be replaced with the cloned defs from
704  // VM. The uses of BB's Phi (if it exists) in BB will be replaced by the
705  // incoming def into the Phi from P1.
706  // Instructions cloned into the predecessor are in practice sometimes
707  // simplified, so disable the use of the template, and create an access from
708  // scratch.
709  PhiToDefMap MPhiMap;
710  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB))
711  MPhiMap[MPhi] = MPhi->getIncomingValueForBlock(P1);
712  cloneUsesAndDefs(BB, P1, VM, MPhiMap, /*CloneWasSimplified=*/true);
713 }
714 
715 template <typename Iter>
716 void MemorySSAUpdater::privateUpdateExitBlocksForClonedLoop(
717  ArrayRef<BasicBlock *> ExitBlocks, Iter ValuesBegin, Iter ValuesEnd,
718  DominatorTree &DT) {
720  // Update/insert phis in all successors of exit blocks.
721  for (auto *Exit : ExitBlocks)
722  for (const ValueToValueMapTy *VMap : make_range(ValuesBegin, ValuesEnd))
723  if (BasicBlock *NewExit = cast_or_null<BasicBlock>(VMap->lookup(Exit))) {
724  BasicBlock *ExitSucc = NewExit->getTerminator()->getSuccessor(0);
725  Updates.push_back({DT.Insert, NewExit, ExitSucc});
726  }
727  applyInsertUpdates(Updates, DT);
728 }
729 
731  ArrayRef<BasicBlock *> ExitBlocks, const ValueToValueMapTy &VMap,
732  DominatorTree &DT) {
733  const ValueToValueMapTy *const Arr[] = {&VMap};
734  privateUpdateExitBlocksForClonedLoop(ExitBlocks, std::begin(Arr),
735  std::end(Arr), DT);
736 }
737 
739  ArrayRef<BasicBlock *> ExitBlocks,
740  ArrayRef<std::unique_ptr<ValueToValueMapTy>> VMaps, DominatorTree &DT) {
741  auto GetPtr = [&](const std::unique_ptr<ValueToValueMapTy> &I) {
742  return I.get();
743  };
744  using MappedIteratorType =
746  decltype(GetPtr)>;
747  auto MapBegin = MappedIteratorType(VMaps.begin(), GetPtr);
748  auto MapEnd = MappedIteratorType(VMaps.end(), GetPtr);
749  privateUpdateExitBlocksForClonedLoop(ExitBlocks, MapBegin, MapEnd, DT);
750 }
751 
753  DominatorTree &DT) {
754  SmallVector<CFGUpdate, 4> RevDeleteUpdates;
755  SmallVector<CFGUpdate, 4> InsertUpdates;
756  for (auto &Update : Updates) {
757  if (Update.getKind() == DT.Insert)
758  InsertUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
759  else
760  RevDeleteUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
761  }
762 
763  if (!RevDeleteUpdates.empty()) {
764  // Update for inserted edges: use newDT and snapshot CFG as if deletes had
765  // not occurred.
766  // FIXME: This creates a new DT, so it's more expensive to do mix
767  // delete/inserts vs just inserts. We can do an incremental update on the DT
768  // to revert deletes, than re-delete the edges. Teaching DT to do this, is
769  // part of a pending cleanup.
770  DominatorTree NewDT(DT, RevDeleteUpdates);
771  GraphDiff<BasicBlock *> GD(RevDeleteUpdates);
772  applyInsertUpdates(InsertUpdates, NewDT, &GD);
773  } else {
775  applyInsertUpdates(InsertUpdates, DT, &GD);
776  }
777 
778  // Update for deleted edges
779  for (auto &Update : RevDeleteUpdates)
780  removeEdge(Update.getFrom(), Update.getTo());
781 }
782 
784  DominatorTree &DT) {
786  applyInsertUpdates(Updates, DT, &GD);
787 }
788 
790  DominatorTree &DT,
791  const GraphDiff<BasicBlock *> *GD) {
792  // Get recursive last Def, assuming well formed MSSA and updated DT.
793  auto GetLastDef = [&](BasicBlock *BB) -> MemoryAccess * {
794  while (true) {
795  MemorySSA::DefsList *Defs = MSSA->getWritableBlockDefs(BB);
796  // Return last Def or Phi in BB, if it exists.
797  if (Defs)
798  return &*(--Defs->end());
799 
800  // Check number of predecessors, we only care if there's more than one.
801  unsigned Count = 0;
802  BasicBlock *Pred = nullptr;
803  for (auto &Pair : children<GraphDiffInvBBPair>({GD, BB})) {
804  Pred = Pair.second;
805  Count++;
806  if (Count == 2)
807  break;
808  }
809 
810  // If BB has multiple predecessors, get last definition from IDom.
811  if (Count != 1) {
812  // [SimpleLoopUnswitch] If BB is a dead block, about to be deleted, its
813  // DT is invalidated. Return LoE as its last def. This will be added to
814  // MemoryPhi node, and later deleted when the block is deleted.
815  if (!DT.getNode(BB))
816  return MSSA->getLiveOnEntryDef();
817  if (auto *IDom = DT.getNode(BB)->getIDom())
818  if (IDom->getBlock() != BB) {
819  BB = IDom->getBlock();
820  continue;
821  }
822  return MSSA->getLiveOnEntryDef();
823  } else {
824  // Single predecessor, BB cannot be dead. GetLastDef of Pred.
825  assert(Count == 1 && Pred && "Single predecessor expected.");
826  BB = Pred;
827  }
828  };
829  llvm_unreachable("Unable to get last definition.");
830  };
831 
832  // Get nearest IDom given a set of blocks.
833  // TODO: this can be optimized by starting the search at the node with the
834  // lowest level (highest in the tree).
835  auto FindNearestCommonDominator =
836  [&](const SmallSetVector<BasicBlock *, 2> &BBSet) -> BasicBlock * {
837  BasicBlock *PrevIDom = *BBSet.begin();
838  for (auto *BB : BBSet)
839  PrevIDom = DT.findNearestCommonDominator(PrevIDom, BB);
840  return PrevIDom;
841  };
842 
843  // Get all blocks that dominate PrevIDom, stop when reaching CurrIDom. Do not
844  // include CurrIDom.
845  auto GetNoLongerDomBlocks =
846  [&](BasicBlock *PrevIDom, BasicBlock *CurrIDom,
847  SmallVectorImpl<BasicBlock *> &BlocksPrevDom) {
848  if (PrevIDom == CurrIDom)
849  return;
850  BlocksPrevDom.push_back(PrevIDom);
851  BasicBlock *NextIDom = PrevIDom;
852  while (BasicBlock *UpIDom =
853  DT.getNode(NextIDom)->getIDom()->getBlock()) {
854  if (UpIDom == CurrIDom)
855  break;
856  BlocksPrevDom.push_back(UpIDom);
857  NextIDom = UpIDom;
858  }
859  };
860 
861  // Map a BB to its predecessors: added + previously existing. To get a
862  // deterministic order, store predecessors as SetVectors. The order in each
863  // will be defined by the order in Updates (fixed) and the order given by
864  // children<> (also fixed). Since we further iterate over these ordered sets,
865  // we lose the information of multiple edges possibly existing between two
866  // blocks, so we'll keep and EdgeCount map for that.
867  // An alternate implementation could keep unordered set for the predecessors,
868  // traverse either Updates or children<> each time to get the deterministic
869  // order, and drop the usage of EdgeCount. This alternate approach would still
870  // require querying the maps for each predecessor, and children<> call has
871  // additional computation inside for creating the snapshot-graph predecessors.
872  // As such, we favor using a little additional storage and less compute time.
873  // This decision can be revisited if we find the alternative more favorable.
874 
875  struct PredInfo {
878  };
880 
881  for (auto &Edge : Updates) {
882  BasicBlock *BB = Edge.getTo();
883  auto &AddedBlockSet = PredMap[BB].Added;
884  AddedBlockSet.insert(Edge.getFrom());
885  }
886 
887  // Store all existing predecessor for each BB, at least one must exist.
890  for (auto &BBPredPair : PredMap) {
891  auto *BB = BBPredPair.first;
892  const auto &AddedBlockSet = BBPredPair.second.Added;
893  auto &PrevBlockSet = BBPredPair.second.Prev;
894  for (auto &Pair : children<GraphDiffInvBBPair>({GD, BB})) {
895  BasicBlock *Pi = Pair.second;
896  if (!AddedBlockSet.count(Pi))
897  PrevBlockSet.insert(Pi);
898  EdgeCountMap[{Pi, BB}]++;
899  }
900 
901  if (PrevBlockSet.empty()) {
902  assert(pred_size(BB) == AddedBlockSet.size() && "Duplicate edges added.");
903  LLVM_DEBUG(
904  dbgs()
905  << "Adding a predecessor to a block with no predecessors. "
906  "This must be an edge added to a new, likely cloned, block. "
907  "Its memory accesses must be already correct, assuming completed "
908  "via the updateExitBlocksForClonedLoop API. "
909  "Assert a single such edge is added so no phi addition or "
910  "additional processing is required.\n");
911  assert(AddedBlockSet.size() == 1 &&
912  "Can only handle adding one predecessor to a new block.");
913  // Need to remove new blocks from PredMap. Remove below to not invalidate
914  // iterator here.
915  NewBlocks.insert(BB);
916  }
917  }
918  // Nothing to process for new/cloned blocks.
919  for (auto *BB : NewBlocks)
920  PredMap.erase(BB);
921 
922  SmallVector<BasicBlock *, 16> BlocksWithDefsToReplace;
923  SmallVector<WeakVH, 8> InsertedPhis;
924 
925  // First create MemoryPhis in all blocks that don't have one. Create in the
926  // order found in Updates, not in PredMap, to get deterministic numbering.
927  for (auto &Edge : Updates) {
928  BasicBlock *BB = Edge.getTo();
929  if (PredMap.count(BB) && !MSSA->getMemoryAccess(BB))
930  InsertedPhis.push_back(MSSA->createMemoryPhi(BB));
931  }
932 
933  // Now we'll fill in the MemoryPhis with the right incoming values.
934  for (auto &BBPredPair : PredMap) {
935  auto *BB = BBPredPair.first;
936  const auto &PrevBlockSet = BBPredPair.second.Prev;
937  const auto &AddedBlockSet = BBPredPair.second.Added;
938  assert(!PrevBlockSet.empty() &&
939  "At least one previous predecessor must exist.");
940 
941  // TODO: if this becomes a bottleneck, we can save on GetLastDef calls by
942  // keeping this map before the loop. We can reuse already populated entries
943  // if an edge is added from the same predecessor to two different blocks,
944  // and this does happen in rotate. Note that the map needs to be updated
945  // when deleting non-necessary phis below, if the phi is in the map by
946  // replacing the value with DefP1.
948  for (auto *AddedPred : AddedBlockSet) {
949  auto *DefPn = GetLastDef(AddedPred);
950  assert(DefPn != nullptr && "Unable to find last definition.");
951  LastDefAddedPred[AddedPred] = DefPn;
952  }
953 
954  MemoryPhi *NewPhi = MSSA->getMemoryAccess(BB);
955  // If Phi is not empty, add an incoming edge from each added pred. Must
956  // still compute blocks with defs to replace for this block below.
957  if (NewPhi->getNumOperands()) {
958  for (auto *Pred : AddedBlockSet) {
959  auto *LastDefForPred = LastDefAddedPred[Pred];
960  for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
961  NewPhi->addIncoming(LastDefForPred, Pred);
962  }
963  } else {
964  // Pick any existing predecessor and get its definition. All other
965  // existing predecessors should have the same one, since no phi existed.
966  auto *P1 = *PrevBlockSet.begin();
967  MemoryAccess *DefP1 = GetLastDef(P1);
968 
969  // Check DefP1 against all Defs in LastDefPredPair. If all the same,
970  // nothing to add.
971  bool InsertPhi = false;
972  for (auto LastDefPredPair : LastDefAddedPred)
973  if (DefP1 != LastDefPredPair.second) {
974  InsertPhi = true;
975  break;
976  }
977  if (!InsertPhi) {
978  // Since NewPhi may be used in other newly added Phis, replace all uses
979  // of NewPhi with the definition coming from all predecessors (DefP1),
980  // before deleting it.
981  NewPhi->replaceAllUsesWith(DefP1);
982  removeMemoryAccess(NewPhi);
983  continue;
984  }
985 
986  // Update Phi with new values for new predecessors and old value for all
987  // other predecessors. Since AddedBlockSet and PrevBlockSet are ordered
988  // sets, the order of entries in NewPhi is deterministic.
989  for (auto *Pred : AddedBlockSet) {
990  auto *LastDefForPred = LastDefAddedPred[Pred];
991  for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
992  NewPhi->addIncoming(LastDefForPred, Pred);
993  }
994  for (auto *Pred : PrevBlockSet)
995  for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
996  NewPhi->addIncoming(DefP1, Pred);
997  }
998 
999  // Get all blocks that used to dominate BB and no longer do after adding
1000  // AddedBlockSet, where PrevBlockSet are the previously known predecessors.
1001  assert(DT.getNode(BB)->getIDom() && "BB does not have valid idom");
1002  BasicBlock *PrevIDom = FindNearestCommonDominator(PrevBlockSet);
1003  assert(PrevIDom && "Previous IDom should exists");
1004  BasicBlock *NewIDom = DT.getNode(BB)->getIDom()->getBlock();
1005  assert(NewIDom && "BB should have a new valid idom");
1006  assert(DT.dominates(NewIDom, PrevIDom) &&
1007  "New idom should dominate old idom");
1008  GetNoLongerDomBlocks(PrevIDom, NewIDom, BlocksWithDefsToReplace);
1009  }
1010 
1011  tryRemoveTrivialPhis(InsertedPhis);
1012  // Create the set of blocks that now have a definition. We'll use this to
1013  // compute IDF and add Phis there next.
1014  SmallVector<BasicBlock *, 8> BlocksToProcess;
1015  for (auto &VH : InsertedPhis)
1016  if (auto *MPhi = cast_or_null<MemoryPhi>(VH))
1017  BlocksToProcess.push_back(MPhi->getBlock());
1018 
1019  // Compute IDF and add Phis in all IDF blocks that do not have one.
1021  if (!BlocksToProcess.empty()) {
1022  ForwardIDFCalculator IDFs(DT, GD);
1023  SmallPtrSet<BasicBlock *, 16> DefiningBlocks(BlocksToProcess.begin(),
1024  BlocksToProcess.end());
1025  IDFs.setDefiningBlocks(DefiningBlocks);
1026  IDFs.calculate(IDFBlocks);
1027 
1028  SmallSetVector<MemoryPhi *, 4> PhisToFill;
1029  // First create all needed Phis.
1030  for (auto *BBIDF : IDFBlocks)
1031  if (!MSSA->getMemoryAccess(BBIDF)) {
1032  auto *IDFPhi = MSSA->createMemoryPhi(BBIDF);
1033  InsertedPhis.push_back(IDFPhi);
1034  PhisToFill.insert(IDFPhi);
1035  }
1036  // Then update or insert their correct incoming values.
1037  for (auto *BBIDF : IDFBlocks) {
1038  auto *IDFPhi = MSSA->getMemoryAccess(BBIDF);
1039  assert(IDFPhi && "Phi must exist");
1040  if (!PhisToFill.count(IDFPhi)) {
1041  // Update existing Phi.
1042  // FIXME: some updates may be redundant, try to optimize and skip some.
1043  for (unsigned I = 0, E = IDFPhi->getNumIncomingValues(); I < E; ++I)
1044  IDFPhi->setIncomingValue(I, GetLastDef(IDFPhi->getIncomingBlock(I)));
1045  } else {
1046  for (auto &Pair : children<GraphDiffInvBBPair>({GD, BBIDF})) {
1047  BasicBlock *Pi = Pair.second;
1048  IDFPhi->addIncoming(GetLastDef(Pi), Pi);
1049  }
1050  }
1051  }
1052  }
1053 
1054  // Now for all defs in BlocksWithDefsToReplace, if there are uses they no
1055  // longer dominate, replace those with the closest dominating def.
1056  // This will also update optimized accesses, as they're also uses.
1057  for (auto *BlockWithDefsToReplace : BlocksWithDefsToReplace) {
1058  if (auto DefsList = MSSA->getWritableBlockDefs(BlockWithDefsToReplace)) {
1059  for (auto &DefToReplaceUses : *DefsList) {
1060  BasicBlock *DominatingBlock = DefToReplaceUses.getBlock();
1061  Value::use_iterator UI = DefToReplaceUses.use_begin(),
1062  E = DefToReplaceUses.use_end();
1063  for (; UI != E;) {
1064  Use &U = *UI;
1065  ++UI;
1067  if (MemoryPhi *UsrPhi = dyn_cast<MemoryPhi>(Usr)) {
1068  BasicBlock *DominatedBlock = UsrPhi->getIncomingBlock(U);
1069  if (!DT.dominates(DominatingBlock, DominatedBlock))
1070  U.set(GetLastDef(DominatedBlock));
1071  } else {
1072  BasicBlock *DominatedBlock = Usr->getBlock();
1073  if (!DT.dominates(DominatingBlock, DominatedBlock)) {
1074  if (auto *DomBlPhi = MSSA->getMemoryAccess(DominatedBlock))
1075  U.set(DomBlPhi);
1076  else {
1077  auto *IDom = DT.getNode(DominatedBlock)->getIDom();
1078  assert(IDom && "Block must have a valid IDom.");
1079  U.set(GetLastDef(IDom->getBlock()));
1080  }
1081  cast<MemoryUseOrDef>(Usr)->resetOptimized();
1082  }
1083  }
1084  }
1085  }
1086  }
1087  }
1088  tryRemoveTrivialPhis(InsertedPhis);
1089 }
1090 
1091 // Move What before Where in the MemorySSA IR.
1092 template <class WhereType>
1093 void MemorySSAUpdater::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
1094  WhereType Where) {
1095  // Mark MemoryPhi users of What not to be optimized.
1096  for (auto *U : What->users())
1097  if (MemoryPhi *PhiUser = dyn_cast<MemoryPhi>(U))
1098  NonOptPhis.insert(PhiUser);
1099 
1100  // Replace all our users with our defining access.
1101  What->replaceAllUsesWith(What->getDefiningAccess());
1102 
1103  // Let MemorySSA take care of moving it around in the lists.
1104  MSSA->moveTo(What, BB, Where);
1105 
1106  // Now reinsert it into the IR and do whatever fixups needed.
1107  if (auto *MD = dyn_cast<MemoryDef>(What))
1108  insertDef(MD, /*RenameUses=*/true);
1109  else
1110  insertUse(cast<MemoryUse>(What), /*RenameUses=*/true);
1111 
1112  // Clear dangling pointers. We added all MemoryPhi users, but not all
1113  // of them are removed by fixupDefs().
1114  NonOptPhis.clear();
1115 }
1116 
1117 // Move What before Where in the MemorySSA IR.
1119  moveTo(What, Where->getBlock(), Where->getIterator());
1120 }
1121 
1122 // Move What after Where in the MemorySSA IR.
1124  moveTo(What, Where->getBlock(), ++Where->getIterator());
1125 }
1126 
1128  MemorySSA::InsertionPlace Where) {
1129  return moveTo(What, BB, Where);
1130 }
1131 
1132 // All accesses in To used to be in From. Move to end and update access lists.
1133 void MemorySSAUpdater::moveAllAccesses(BasicBlock *From, BasicBlock *To,
1134  Instruction *Start) {
1135 
1136  MemorySSA::AccessList *Accs = MSSA->getWritableBlockAccesses(From);
1137  if (!Accs)
1138  return;
1139 
1140  MemoryAccess *FirstInNew = nullptr;
1141  for (Instruction &I : make_range(Start->getIterator(), To->end()))
1142  if ((FirstInNew = MSSA->getMemoryAccess(&I)))
1143  break;
1144  if (!FirstInNew)
1145  return;
1146 
1147  auto *MUD = cast<MemoryUseOrDef>(FirstInNew);
1148  do {
1149  auto NextIt = ++MUD->getIterator();
1150  MemoryUseOrDef *NextMUD = (!Accs || NextIt == Accs->end())
1151  ? nullptr
1152  : cast<MemoryUseOrDef>(&*NextIt);
1153  MSSA->moveTo(MUD, To, MemorySSA::End);
1154  // Moving MUD from Accs in the moveTo above, may delete Accs, so we need to
1155  // retrieve it again.
1156  Accs = MSSA->getWritableBlockAccesses(From);
1157  MUD = NextMUD;
1158  } while (MUD);
1159 }
1160 
1162  BasicBlock *To,
1163  Instruction *Start) {
1164  assert(MSSA->getBlockAccesses(To) == nullptr &&
1165  "To block is expected to be free of MemoryAccesses.");
1166  moveAllAccesses(From, To, Start);
1167  for (BasicBlock *Succ : successors(To))
1168  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Succ))
1169  MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
1170 }
1171 
1173  Instruction *Start) {
1174  assert(From->getSinglePredecessor() == To &&
1175  "From block is expected to have a single predecessor (To).");
1176  moveAllAccesses(From, To, Start);
1177  for (BasicBlock *Succ : successors(From))
1178  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Succ))
1179  MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
1180 }
1181 
1182 /// If all arguments of a MemoryPHI are defined by the same incoming
1183 /// argument, return that argument.
1185  MemoryAccess *MA = nullptr;
1186 
1187  for (auto &Arg : MP->operands()) {
1188  if (!MA)
1189  MA = cast<MemoryAccess>(Arg);
1190  else if (MA != Arg)
1191  return nullptr;
1192  }
1193  return MA;
1194 }
1195 
1197  BasicBlock *Old, BasicBlock *New, ArrayRef<BasicBlock *> Preds,
1198  bool IdenticalEdgesWereMerged) {
1199  assert(!MSSA->getWritableBlockAccesses(New) &&
1200  "Access list should be null for a new block.");
1201  MemoryPhi *Phi = MSSA->getMemoryAccess(Old);
1202  if (!Phi)
1203  return;
1204  if (Old->hasNPredecessors(1)) {
1205  assert(pred_size(New) == Preds.size() &&
1206  "Should have moved all predecessors.");
1207  MSSA->moveTo(Phi, New, MemorySSA::Beginning);
1208  } else {
1209  assert(!Preds.empty() && "Must be moving at least one predecessor to the "
1210  "new immediate predecessor.");
1211  MemoryPhi *NewPhi = MSSA->createMemoryPhi(New);
1212  SmallPtrSet<BasicBlock *, 16> PredsSet(Preds.begin(), Preds.end());
1213  // Currently only support the case of removing a single incoming edge when
1214  // identical edges were not merged.
1215  if (!IdenticalEdgesWereMerged)
1216  assert(PredsSet.size() == Preds.size() &&
1217  "If identical edges were not merged, we cannot have duplicate "
1218  "blocks in the predecessors");
1219  Phi->unorderedDeleteIncomingIf([&](MemoryAccess *MA, BasicBlock *B) {
1220  if (PredsSet.count(B)) {
1221  NewPhi->addIncoming(MA, B);
1222  if (!IdenticalEdgesWereMerged)
1223  PredsSet.erase(B);
1224  return true;
1225  }
1226  return false;
1227  });
1228  Phi->addIncoming(NewPhi, New);
1229  tryRemoveTrivialPhi(NewPhi);
1230  }
1231 }
1232 
1234  assert(!MSSA->isLiveOnEntryDef(MA) &&
1235  "Trying to remove the live on entry def");
1236  // We can only delete phi nodes if they have no uses, or we can replace all
1237  // uses with a single definition.
1238  MemoryAccess *NewDefTarget = nullptr;
1239  if (MemoryPhi *MP = dyn_cast<MemoryPhi>(MA)) {
1240  // Note that it is sufficient to know that all edges of the phi node have
1241  // the same argument. If they do, by the definition of dominance frontiers
1242  // (which we used to place this phi), that argument must dominate this phi,
1243  // and thus, must dominate the phi's uses, and so we will not hit the assert
1244  // below.
1245  NewDefTarget = onlySingleValue(MP);
1246  assert((NewDefTarget || MP->use_empty()) &&
1247  "We can't delete this memory phi");
1248  } else {
1249  NewDefTarget = cast<MemoryUseOrDef>(MA)->getDefiningAccess();
1250  }
1251 
1252  SmallSetVector<MemoryPhi *, 4> PhisToCheck;
1253 
1254  // Re-point the uses at our defining access
1255  if (!isa<MemoryUse>(MA) && !MA->use_empty()) {
1256  // Reset optimized on users of this store, and reset the uses.
1257  // A few notes:
1258  // 1. This is a slightly modified version of RAUW to avoid walking the
1259  // uses twice here.
1260  // 2. If we wanted to be complete, we would have to reset the optimized
1261  // flags on users of phi nodes if doing the below makes a phi node have all
1262  // the same arguments. Instead, we prefer users to removeMemoryAccess those
1263  // phi nodes, because doing it here would be N^3.
1264  if (MA->hasValueHandle())
1265  ValueHandleBase::ValueIsRAUWd(MA, NewDefTarget);
1266  // Note: We assume MemorySSA is not used in metadata since it's not really
1267  // part of the IR.
1268 
1269  while (!MA->use_empty()) {
1270  Use &U = *MA->use_begin();
1271  if (auto *MUD = dyn_cast<MemoryUseOrDef>(U.getUser()))
1272  MUD->resetOptimized();
1273  if (OptimizePhis)
1274  if (MemoryPhi *MP = dyn_cast<MemoryPhi>(U.getUser()))
1275  PhisToCheck.insert(MP);
1276  U.set(NewDefTarget);
1277  }
1278  }
1279 
1280  // The call below to erase will destroy MA, so we can't change the order we
1281  // are doing things here
1282  MSSA->removeFromLookups(MA);
1283  MSSA->removeFromLists(MA);
1284 
1285  // Optionally optimize Phi uses. This will recursively remove trivial phis.
1286  if (!PhisToCheck.empty()) {
1287  SmallVector<WeakVH, 16> PhisToOptimize{PhisToCheck.begin(),
1288  PhisToCheck.end()};
1289  PhisToCheck.clear();
1290 
1291  unsigned PhisSize = PhisToOptimize.size();
1292  while (PhisSize-- > 0)
1293  if (MemoryPhi *MP =
1294  cast_or_null<MemoryPhi>(PhisToOptimize.pop_back_val()))
1295  tryRemoveTrivialPhi(MP);
1296  }
1297 }
1298 
1300  const SmallSetVector<BasicBlock *, 8> &DeadBlocks) {
1301  // First delete all uses of BB in MemoryPhis.
1302  for (BasicBlock *BB : DeadBlocks) {
1303  Instruction *TI = BB->getTerminator();
1304  assert(TI && "Basic block expected to have a terminator instruction");
1305  for (BasicBlock *Succ : successors(TI))
1306  if (!DeadBlocks.count(Succ))
1307  if (MemoryPhi *MP = MSSA->getMemoryAccess(Succ)) {
1308  MP->unorderedDeleteIncomingBlock(BB);
1309  tryRemoveTrivialPhi(MP);
1310  }
1311  // Drop all references of all accesses in BB
1312  if (MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB))
1313  for (MemoryAccess &MA : *Acc)
1314  MA.dropAllReferences();
1315  }
1316 
1317  // Next, delete all memory accesses in each block
1318  for (BasicBlock *BB : DeadBlocks) {
1319  MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB);
1320  if (!Acc)
1321  continue;
1322  for (auto AB = Acc->begin(), AE = Acc->end(); AB != AE;) {
1323  MemoryAccess *MA = &*AB;
1324  ++AB;
1325  MSSA->removeFromLookups(MA);
1326  MSSA->removeFromLists(MA);
1327  }
1328  }
1329 }
1330 
1331 void MemorySSAUpdater::tryRemoveTrivialPhis(ArrayRef<WeakVH> UpdatedPHIs) {
1332  for (auto &VH : UpdatedPHIs)
1333  if (auto *MPhi = cast_or_null<MemoryPhi>(VH))
1334  tryRemoveTrivialPhi(MPhi);
1335 }
1336 
1338  const BasicBlock *BB = I->getParent();
1339  // Remove memory accesses in BB for I and all following instructions.
1340  auto BBI = I->getIterator(), BBE = BB->end();
1341  // FIXME: If this becomes too expensive, iterate until the first instruction
1342  // with a memory access, then iterate over MemoryAccesses.
1343  while (BBI != BBE)
1344  removeMemoryAccess(&*(BBI++));
1345  // Update phis in BB's successors to remove BB.
1346  SmallVector<WeakVH, 16> UpdatedPHIs;
1347  for (const BasicBlock *Successor : successors(BB)) {
1349  if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Successor)) {
1350  MPhi->unorderedDeleteIncomingBlock(BB);
1351  UpdatedPHIs.push_back(MPhi);
1352  }
1353  }
1354  // Optimize trivial phis.
1355  tryRemoveTrivialPhis(UpdatedPHIs);
1356 }
1357 
1359  const BasicBlock *To) {
1360  const BasicBlock *BB = BI->getParent();
1361  SmallVector<WeakVH, 16> UpdatedPHIs;
1362  for (const BasicBlock *Succ : successors(BB)) {
1364  if (Succ != To)
1365  if (auto *MPhi = MSSA->getMemoryAccess(Succ)) {
1366  MPhi->unorderedDeleteIncomingBlock(BB);
1367  UpdatedPHIs.push_back(MPhi);
1368  }
1369  }
1370  // Optimize trivial phis.
1371  tryRemoveTrivialPhis(UpdatedPHIs);
1372 }
1373 
1375  Instruction *I, MemoryAccess *Definition, const BasicBlock *BB,
1376  MemorySSA::InsertionPlace Point) {
1377  MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1378  MSSA->insertIntoListsForBlock(NewAccess, BB, Point);
1379  return NewAccess;
1380 }
1381 
1383  Instruction *I, MemoryAccess *Definition, MemoryUseOrDef *InsertPt) {
1384  assert(I->getParent() == InsertPt->getBlock() &&
1385  "New and old access must be in the same block");
1386  MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1387  MSSA->insertIntoListsBefore(NewAccess, InsertPt->getBlock(),
1388  InsertPt->getIterator());
1389  return NewAccess;
1390 }
1391 
1393  Instruction *I, MemoryAccess *Definition, MemoryAccess *InsertPt) {
1394  assert(I->getParent() == InsertPt->getBlock() &&
1395  "New and old access must be in the same block");
1396  MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1397  MSSA->insertIntoListsBefore(NewAccess, InsertPt->getBlock(),
1398  ++InsertPt->getIterator());
1399  return NewAccess;
1400 }
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:233
AccessList * getWritableBlockAccesses(const BasicBlock *BB) const
Definition: MemorySSA.h:803
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:2120
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.
void insertUse(MemoryUse *Use, bool RenameUses=false)
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:505
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...
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:822
block_iterator block_begin()
Definition: MemorySSA.h:500
MemoryUseOrDef * createDefinedAccess(Instruction *, MemoryAccess *, const MemoryUseOrDef *Template=nullptr, bool CreationMustSucceed=true)
Definition: MemorySSA.cpp:1689
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
Encapsulates MemorySSA, including all data associated with memory accesses.
Definition: MemorySSA.h:703
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:1582
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:925
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
void replaceUsesWithIf(Value *New, llvm::function_ref< bool(Use &U)> ShouldReplace)
Go through the uses list for this definition and make each use point to "V" if the callback ShouldRep...
Definition: Value.h:300
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:351
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:730
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)
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.
static MemoryAccess * getNewDefiningAccessForClone(MemoryAccess *MA, const ValueToValueMapTy &VMap, PhiToDefMap &MPhiMap, bool CloneWasSimplified, MemorySSA *MSSA)
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:419
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:358
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:395
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:809
#define LLVM_DEBUG(X)
Definition: Debug.h:122
OutputIt copy(R &&Range, OutputIt Out)
Definition: STLExtras.h:1229
void moveBefore(MemoryUseOrDef *What, MemoryUseOrDef *Where)
void updateForClonedBlockIntoPred(BasicBlock *BB, BasicBlock *P1, const ValueToValueMapTy &VM)
bool use_empty() const
Definition: Value.h:342
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:403