clang  8.0.0svn
CGCleanup.cpp
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1 //===--- CGCleanup.cpp - Bookkeeping and code emission for cleanups -------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains code dealing with the IR generation for cleanups
11 // and related information.
12 //
13 // A "cleanup" is a piece of code which needs to be executed whenever
14 // control transfers out of a particular scope. This can be
15 // conditionalized to occur only on exceptional control flow, only on
16 // normal control flow, or both.
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #include "CGCleanup.h"
21 #include "CodeGenFunction.h"
22 #include "llvm/Support/SaveAndRestore.h"
23 
24 using namespace clang;
25 using namespace CodeGen;
26 
28  if (rv.isScalar())
30  if (rv.isAggregate())
32  return true;
33 }
34 
37  if (rv.isScalar()) {
38  llvm::Value *V = rv.getScalarVal();
39 
40  // These automatically dominate and don't need to be saved.
42  return saved_type(V, ScalarLiteral);
43 
44  // Everything else needs an alloca.
45  Address addr =
46  CGF.CreateDefaultAlignTempAlloca(V->getType(), "saved-rvalue");
47  CGF.Builder.CreateStore(V, addr);
48  return saved_type(addr.getPointer(), ScalarAddress);
49  }
50 
51  if (rv.isComplex()) {
53  llvm::Type *ComplexTy =
54  llvm::StructType::get(V.first->getType(), V.second->getType());
55  Address addr = CGF.CreateDefaultAlignTempAlloca(ComplexTy, "saved-complex");
56  CGF.Builder.CreateStore(V.first,
57  CGF.Builder.CreateStructGEP(addr, 0, CharUnits()));
59  CGF.CGM.getDataLayout().getTypeAllocSize(V.first->getType()));
60  CGF.Builder.CreateStore(V.second,
61  CGF.Builder.CreateStructGEP(addr, 1, offset));
62  return saved_type(addr.getPointer(), ComplexAddress);
63  }
64 
65  assert(rv.isAggregate());
66  Address V = rv.getAggregateAddress(); // TODO: volatile?
67  if (!DominatingLLVMValue::needsSaving(V.getPointer()))
68  return saved_type(V.getPointer(), AggregateLiteral,
69  V.getAlignment().getQuantity());
70 
71  Address addr =
72  CGF.CreateTempAlloca(V.getType(), CGF.getPointerAlign(), "saved-rvalue");
73  CGF.Builder.CreateStore(V.getPointer(), addr);
74  return saved_type(addr.getPointer(), AggregateAddress,
75  V.getAlignment().getQuantity());
76 }
77 
78 /// Given a saved r-value produced by SaveRValue, perform the code
79 /// necessary to restore it to usability at the current insertion
80 /// point.
82  auto getSavingAddress = [&](llvm::Value *value) {
83  auto alignment = cast<llvm::AllocaInst>(value)->getAlignment();
84  return Address(value, CharUnits::fromQuantity(alignment));
85  };
86  switch (K) {
87  case ScalarLiteral:
88  return RValue::get(Value);
89  case ScalarAddress:
90  return RValue::get(CGF.Builder.CreateLoad(getSavingAddress(Value)));
91  case AggregateLiteral:
93  case AggregateAddress: {
94  auto addr = CGF.Builder.CreateLoad(getSavingAddress(Value));
96  }
97  case ComplexAddress: {
98  Address address = getSavingAddress(Value);
99  llvm::Value *real = CGF.Builder.CreateLoad(
100  CGF.Builder.CreateStructGEP(address, 0, CharUnits()));
102  CGF.CGM.getDataLayout().getTypeAllocSize(real->getType()));
103  llvm::Value *imag = CGF.Builder.CreateLoad(
104  CGF.Builder.CreateStructGEP(address, 1, offset));
105  return RValue::getComplex(real, imag);
106  }
107  }
108 
109  llvm_unreachable("bad saved r-value kind");
110 }
111 
112 /// Push an entry of the given size onto this protected-scope stack.
113 char *EHScopeStack::allocate(size_t Size) {
114  Size = llvm::alignTo(Size, ScopeStackAlignment);
115  if (!StartOfBuffer) {
116  unsigned Capacity = 1024;
117  while (Capacity < Size) Capacity *= 2;
118  StartOfBuffer = new char[Capacity];
119  StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
120  } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
121  unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
122  unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
123 
124  unsigned NewCapacity = CurrentCapacity;
125  do {
126  NewCapacity *= 2;
127  } while (NewCapacity < UsedCapacity + Size);
128 
129  char *NewStartOfBuffer = new char[NewCapacity];
130  char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
131  char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
132  memcpy(NewStartOfData, StartOfData, UsedCapacity);
133  delete [] StartOfBuffer;
134  StartOfBuffer = NewStartOfBuffer;
135  EndOfBuffer = NewEndOfBuffer;
136  StartOfData = NewStartOfData;
137  }
138 
139  assert(StartOfBuffer + Size <= StartOfData);
140  StartOfData -= Size;
141  return StartOfData;
142 }
143 
144 void EHScopeStack::deallocate(size_t Size) {
145  StartOfData += llvm::alignTo(Size, ScopeStackAlignment);
146 }
147 
149  EHScopeStack::stable_iterator Old) const {
150  for (EHScopeStack::iterator it = begin(); stabilize(it) != Old; it++) {
151  EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*it);
152  if (!cleanup || !cleanup->isLifetimeMarker())
153  return false;
154  }
155 
156  return true;
157 }
158 
160  for (stable_iterator si = getInnermostEHScope(); si != stable_end(); ) {
161  // Skip lifetime markers.
162  if (auto *cleanup = dyn_cast<EHCleanupScope>(&*find(si)))
163  if (cleanup->isLifetimeMarker()) {
164  si = cleanup->getEnclosingEHScope();
165  continue;
166  }
167  return true;
168  }
169 
170  return false;
171 }
172 
176  si != se; ) {
177  EHCleanupScope &cleanup = cast<EHCleanupScope>(*find(si));
178  if (cleanup.isActive()) return si;
179  si = cleanup.getEnclosingNormalCleanup();
180  }
181  return stable_end();
182 }
183 
184 
185 void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
186  char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
187  bool IsNormalCleanup = Kind & NormalCleanup;
188  bool IsEHCleanup = Kind & EHCleanup;
189  bool IsActive = !(Kind & InactiveCleanup);
190  bool IsLifetimeMarker = Kind & LifetimeMarker;
192  new (Buffer) EHCleanupScope(IsNormalCleanup,
193  IsEHCleanup,
194  IsActive,
195  Size,
196  BranchFixups.size(),
197  InnermostNormalCleanup,
198  InnermostEHScope);
199  if (IsNormalCleanup)
200  InnermostNormalCleanup = stable_begin();
201  if (IsEHCleanup)
202  InnermostEHScope = stable_begin();
203  if (IsLifetimeMarker)
204  Scope->setLifetimeMarker();
205 
206  return Scope->getCleanupBuffer();
207 }
208 
210  assert(!empty() && "popping exception stack when not empty");
211 
212  assert(isa<EHCleanupScope>(*begin()));
213  EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
214  InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
215  InnermostEHScope = Cleanup.getEnclosingEHScope();
216  deallocate(Cleanup.getAllocatedSize());
217 
218  // Destroy the cleanup.
219  Cleanup.Destroy();
220 
221  // Check whether we can shrink the branch-fixups stack.
222  if (!BranchFixups.empty()) {
223  // If we no longer have any normal cleanups, all the fixups are
224  // complete.
225  if (!hasNormalCleanups())
226  BranchFixups.clear();
227 
228  // Otherwise we can still trim out unnecessary nulls.
229  else
230  popNullFixups();
231  }
232 }
233 
235  assert(getInnermostEHScope() == stable_end());
236  char *buffer = allocate(EHFilterScope::getSizeForNumFilters(numFilters));
237  EHFilterScope *filter = new (buffer) EHFilterScope(numFilters);
238  InnermostEHScope = stable_begin();
239  return filter;
240 }
241 
243  assert(!empty() && "popping exception stack when not empty");
244 
245  EHFilterScope &filter = cast<EHFilterScope>(*begin());
247 
248  InnermostEHScope = filter.getEnclosingEHScope();
249 }
250 
251 EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) {
252  char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers));
253  EHCatchScope *scope =
254  new (buffer) EHCatchScope(numHandlers, InnermostEHScope);
255  InnermostEHScope = stable_begin();
256  return scope;
257 }
258 
260  char *Buffer = allocate(EHTerminateScope::getSize());
261  new (Buffer) EHTerminateScope(InnermostEHScope);
262  InnermostEHScope = stable_begin();
263 }
264 
265 /// Remove any 'null' fixups on the stack. However, we can't pop more
266 /// fixups than the fixup depth on the innermost normal cleanup, or
267 /// else fixups that we try to add to that cleanup will end up in the
268 /// wrong place. We *could* try to shrink fixup depths, but that's
269 /// actually a lot of work for little benefit.
271  // We expect this to only be called when there's still an innermost
272  // normal cleanup; otherwise there really shouldn't be any fixups.
273  assert(hasNormalCleanups());
274 
275  EHScopeStack::iterator it = find(InnermostNormalCleanup);
276  unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
277  assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
278 
279  while (BranchFixups.size() > MinSize &&
280  BranchFixups.back().Destination == nullptr)
281  BranchFixups.pop_back();
282 }
283 
285  // Create a variable to decide whether the cleanup needs to be run.
286  Address active = CreateTempAllocaWithoutCast(
287  Builder.getInt1Ty(), CharUnits::One(), "cleanup.cond");
288 
289  // Initialize it to false at a site that's guaranteed to be run
290  // before each evaluation.
291  setBeforeOutermostConditional(Builder.getFalse(), active);
292 
293  // Initialize it to true at the current location.
294  Builder.CreateStore(Builder.getTrue(), active);
295 
296  return active;
297 }
298 
300  // Set that as the active flag in the cleanup.
301  EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
302  assert(!cleanup.hasActiveFlag() && "cleanup already has active flag?");
303  cleanup.setActiveFlag(ActiveFlag);
304 
305  if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
306  if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
307 }
308 
309 void EHScopeStack::Cleanup::anchor() {}
310 
311 static void createStoreInstBefore(llvm::Value *value, Address addr,
312  llvm::Instruction *beforeInst) {
313  auto store = new llvm::StoreInst(value, addr.getPointer(), beforeInst);
314  store->setAlignment(addr.getAlignment().getQuantity());
315 }
316 
317 static llvm::LoadInst *createLoadInstBefore(Address addr, const Twine &name,
318  llvm::Instruction *beforeInst) {
319  auto load = new llvm::LoadInst(addr.getPointer(), name, beforeInst);
320  load->setAlignment(addr.getAlignment().getQuantity());
321  return load;
322 }
323 
324 /// All the branch fixups on the EH stack have propagated out past the
325 /// outermost normal cleanup; resolve them all by adding cases to the
326 /// given switch instruction.
328  llvm::SwitchInst *Switch,
329  llvm::BasicBlock *CleanupEntry) {
330  llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
331 
332  for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
333  // Skip this fixup if its destination isn't set.
334  BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
335  if (Fixup.Destination == nullptr) continue;
336 
337  // If there isn't an OptimisticBranchBlock, then InitialBranch is
338  // still pointing directly to its destination; forward it to the
339  // appropriate cleanup entry. This is required in the specific
340  // case of
341  // { std::string s; goto lbl; }
342  // lbl:
343  // i.e. where there's an unresolved fixup inside a single cleanup
344  // entry which we're currently popping.
345  if (Fixup.OptimisticBranchBlock == nullptr) {
346  createStoreInstBefore(CGF.Builder.getInt32(Fixup.DestinationIndex),
348  Fixup.InitialBranch);
349  Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
350  }
351 
352  // Don't add this case to the switch statement twice.
353  if (!CasesAdded.insert(Fixup.Destination).second)
354  continue;
355 
356  Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
357  Fixup.Destination);
358  }
359 
360  CGF.EHStack.clearFixups();
361 }
362 
363 /// Transitions the terminator of the given exit-block of a cleanup to
364 /// be a cleanup switch.
365 static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
366  llvm::BasicBlock *Block) {
367  // If it's a branch, turn it into a switch whose default
368  // destination is its original target.
369  llvm::Instruction *Term = Block->getTerminator();
370  assert(Term && "can't transition block without terminator");
371 
372  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
373  assert(Br->isUnconditional());
375  "cleanup.dest", Term);
376  llvm::SwitchInst *Switch =
377  llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
378  Br->eraseFromParent();
379  return Switch;
380  } else {
381  return cast<llvm::SwitchInst>(Term);
382  }
383 }
384 
385 void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
386  assert(Block && "resolving a null target block");
387  if (!EHStack.getNumBranchFixups()) return;
388 
389  assert(EHStack.hasNormalCleanups() &&
390  "branch fixups exist with no normal cleanups on stack");
391 
392  llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
393  bool ResolvedAny = false;
394 
395  for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
396  // Skip this fixup if its destination doesn't match.
397  BranchFixup &Fixup = EHStack.getBranchFixup(I);
398  if (Fixup.Destination != Block) continue;
399 
400  Fixup.Destination = nullptr;
401  ResolvedAny = true;
402 
403  // If it doesn't have an optimistic branch block, LatestBranch is
404  // already pointing to the right place.
405  llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
406  if (!BranchBB)
407  continue;
408 
409  // Don't process the same optimistic branch block twice.
410  if (!ModifiedOptimisticBlocks.insert(BranchBB).second)
411  continue;
412 
413  llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
414 
415  // Add a case to the switch.
416  Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
417  }
418 
419  if (ResolvedAny)
420  EHStack.popNullFixups();
421 }
422 
423 /// Pops cleanup blocks until the given savepoint is reached.
426  std::initializer_list<llvm::Value **> ValuesToReload) {
427  assert(Old.isValid());
428 
429  bool HadBranches = false;
430  while (EHStack.stable_begin() != Old) {
431  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
432  HadBranches |= Scope.hasBranches();
433 
434  // As long as Old strictly encloses the scope's enclosing normal
435  // cleanup, we're going to emit another normal cleanup which
436  // fallthrough can propagate through.
437  bool FallThroughIsBranchThrough =
439 
440  PopCleanupBlock(FallThroughIsBranchThrough);
441  }
442 
443  // If we didn't have any branches, the insertion point before cleanups must
444  // dominate the current insertion point and we don't need to reload any
445  // values.
446  if (!HadBranches)
447  return;
448 
449  // Spill and reload all values that the caller wants to be live at the current
450  // insertion point.
451  for (llvm::Value **ReloadedValue : ValuesToReload) {
452  auto *Inst = dyn_cast_or_null<llvm::Instruction>(*ReloadedValue);
453  if (!Inst)
454  continue;
455 
456  // Don't spill static allocas, they dominate all cleanups. These are created
457  // by binding a reference to a local variable or temporary.
458  auto *AI = dyn_cast<llvm::AllocaInst>(Inst);
459  if (AI && AI->isStaticAlloca())
460  continue;
461 
462  Address Tmp =
463  CreateDefaultAlignTempAlloca(Inst->getType(), "tmp.exprcleanup");
464 
465  // Find an insertion point after Inst and spill it to the temporary.
466  llvm::BasicBlock::iterator InsertBefore;
467  if (auto *Invoke = dyn_cast<llvm::InvokeInst>(Inst))
468  InsertBefore = Invoke->getNormalDest()->getFirstInsertionPt();
469  else
470  InsertBefore = std::next(Inst->getIterator());
471  CGBuilderTy(CGM, &*InsertBefore).CreateStore(Inst, Tmp);
472 
473  // Reload the value at the current insertion point.
474  *ReloadedValue = Builder.CreateLoad(Tmp);
475  }
476 }
477 
478 /// Pops cleanup blocks until the given savepoint is reached, then add the
479 /// cleanups from the given savepoint in the lifetime-extended cleanups stack.
481  EHScopeStack::stable_iterator Old, size_t OldLifetimeExtendedSize,
482  std::initializer_list<llvm::Value **> ValuesToReload) {
483  PopCleanupBlocks(Old, ValuesToReload);
484 
485  // Move our deferred cleanups onto the EH stack.
486  for (size_t I = OldLifetimeExtendedSize,
487  E = LifetimeExtendedCleanupStack.size(); I != E; /**/) {
488  // Alignment should be guaranteed by the vptrs in the individual cleanups.
489  assert((I % alignof(LifetimeExtendedCleanupHeader) == 0) &&
490  "misaligned cleanup stack entry");
491 
493  reinterpret_cast<LifetimeExtendedCleanupHeader&>(
494  LifetimeExtendedCleanupStack[I]);
495  I += sizeof(Header);
496 
497  EHStack.pushCopyOfCleanup(Header.getKind(),
498  &LifetimeExtendedCleanupStack[I],
499  Header.getSize());
500  I += Header.getSize();
501 
502  if (Header.isConditional()) {
503  Address ActiveFlag =
504  reinterpret_cast<Address &>(LifetimeExtendedCleanupStack[I]);
505  initFullExprCleanupWithFlag(ActiveFlag);
506  I += sizeof(ActiveFlag);
507  }
508  }
509  LifetimeExtendedCleanupStack.resize(OldLifetimeExtendedSize);
510 }
511 
512 static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
514  assert(Scope.isNormalCleanup());
515  llvm::BasicBlock *Entry = Scope.getNormalBlock();
516  if (!Entry) {
517  Entry = CGF.createBasicBlock("cleanup");
518  Scope.setNormalBlock(Entry);
519  }
520  return Entry;
521 }
522 
523 /// Attempts to reduce a cleanup's entry block to a fallthrough. This
524 /// is basically llvm::MergeBlockIntoPredecessor, except
525 /// simplified/optimized for the tighter constraints on cleanup blocks.
526 ///
527 /// Returns the new block, whatever it is.
528 static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
529  llvm::BasicBlock *Entry) {
530  llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
531  if (!Pred) return Entry;
532 
533  llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
534  if (!Br || Br->isConditional()) return Entry;
535  assert(Br->getSuccessor(0) == Entry);
536 
537  // If we were previously inserting at the end of the cleanup entry
538  // block, we'll need to continue inserting at the end of the
539  // predecessor.
540  bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
541  assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
542 
543  // Kill the branch.
544  Br->eraseFromParent();
545 
546  // Replace all uses of the entry with the predecessor, in case there
547  // are phis in the cleanup.
548  Entry->replaceAllUsesWith(Pred);
549 
550  // Merge the blocks.
551  Pred->getInstList().splice(Pred->end(), Entry->getInstList());
552 
553  // Kill the entry block.
554  Entry->eraseFromParent();
555 
556  if (WasInsertBlock)
557  CGF.Builder.SetInsertPoint(Pred);
558 
559  return Pred;
560 }
561 
562 static void EmitCleanup(CodeGenFunction &CGF,
565  Address ActiveFlag) {
566  // If there's an active flag, load it and skip the cleanup if it's
567  // false.
568  llvm::BasicBlock *ContBB = nullptr;
569  if (ActiveFlag.isValid()) {
570  ContBB = CGF.createBasicBlock("cleanup.done");
571  llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
572  llvm::Value *IsActive
573  = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
574  CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
575  CGF.EmitBlock(CleanupBB);
576  }
577 
578  // Ask the cleanup to emit itself.
579  Fn->Emit(CGF, flags);
580  assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
581 
582  // Emit the continuation block if there was an active flag.
583  if (ActiveFlag.isValid())
584  CGF.EmitBlock(ContBB);
585 }
586 
587 static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
588  llvm::BasicBlock *From,
589  llvm::BasicBlock *To) {
590  // Exit is the exit block of a cleanup, so it always terminates in
591  // an unconditional branch or a switch.
592  llvm::Instruction *Term = Exit->getTerminator();
593 
594  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
595  assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
596  Br->setSuccessor(0, To);
597  } else {
598  llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
599  for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
600  if (Switch->getSuccessor(I) == From)
601  Switch->setSuccessor(I, To);
602  }
603 }
604 
605 /// We don't need a normal entry block for the given cleanup.
606 /// Optimistic fixup branches can cause these blocks to come into
607 /// existence anyway; if so, destroy it.
608 ///
609 /// The validity of this transformation is very much specific to the
610 /// exact ways in which we form branches to cleanup entries.
612  EHCleanupScope &scope) {
613  llvm::BasicBlock *entry = scope.getNormalBlock();
614  if (!entry) return;
615 
616  // Replace all the uses with unreachable.
617  llvm::BasicBlock *unreachableBB = CGF.getUnreachableBlock();
618  for (llvm::BasicBlock::use_iterator
619  i = entry->use_begin(), e = entry->use_end(); i != e; ) {
620  llvm::Use &use = *i;
621  ++i;
622 
623  use.set(unreachableBB);
624 
625  // The only uses should be fixup switches.
626  llvm::SwitchInst *si = cast<llvm::SwitchInst>(use.getUser());
627  if (si->getNumCases() == 1 && si->getDefaultDest() == unreachableBB) {
628  // Replace the switch with a branch.
629  llvm::BranchInst::Create(si->case_begin()->getCaseSuccessor(), si);
630 
631  // The switch operand is a load from the cleanup-dest alloca.
632  llvm::LoadInst *condition = cast<llvm::LoadInst>(si->getCondition());
633 
634  // Destroy the switch.
635  si->eraseFromParent();
636 
637  // Destroy the load.
638  assert(condition->getOperand(0) == CGF.NormalCleanupDest.getPointer());
639  assert(condition->use_empty());
640  condition->eraseFromParent();
641  }
642  }
643 
644  assert(entry->use_empty());
645  delete entry;
646 }
647 
648 /// Pops a cleanup block. If the block includes a normal cleanup, the
649 /// current insertion point is threaded through the cleanup, as are
650 /// any branch fixups on the cleanup.
651 void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
652  assert(!EHStack.empty() && "cleanup stack is empty!");
653  assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
654  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
655  assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
656 
657  // Remember activation information.
658  bool IsActive = Scope.isActive();
659  Address NormalActiveFlag =
661  : Address::invalid();
662  Address EHActiveFlag =
663  Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag()
664  : Address::invalid();
665 
666  // Check whether we need an EH cleanup. This is only true if we've
667  // generated a lazy EH cleanup block.
668  llvm::BasicBlock *EHEntry = Scope.getCachedEHDispatchBlock();
669  assert(Scope.hasEHBranches() == (EHEntry != nullptr));
670  bool RequiresEHCleanup = (EHEntry != nullptr);
672 
673  // Check the three conditions which might require a normal cleanup:
674 
675  // - whether there are branch fix-ups through this cleanup
676  unsigned FixupDepth = Scope.getFixupDepth();
677  bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
678 
679  // - whether there are branch-throughs or branch-afters
680  bool HasExistingBranches = Scope.hasBranches();
681 
682  // - whether there's a fallthrough
683  llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
684  bool HasFallthrough = (FallthroughSource != nullptr && IsActive);
685 
686  // Branch-through fall-throughs leave the insertion point set to the
687  // end of the last cleanup, which points to the current scope. The
688  // rest of IR gen doesn't need to worry about this; it only happens
689  // during the execution of PopCleanupBlocks().
690  bool HasPrebranchedFallthrough =
691  (FallthroughSource && FallthroughSource->getTerminator());
692 
693  // If this is a normal cleanup, then having a prebranched
694  // fallthrough implies that the fallthrough source unconditionally
695  // jumps here.
696  assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
697  (Scope.getNormalBlock() &&
698  FallthroughSource->getTerminator()->getSuccessor(0)
699  == Scope.getNormalBlock()));
700 
701  bool RequiresNormalCleanup = false;
702  if (Scope.isNormalCleanup() &&
703  (HasFixups || HasExistingBranches || HasFallthrough)) {
704  RequiresNormalCleanup = true;
705  }
706 
707  // If we have a prebranched fallthrough into an inactive normal
708  // cleanup, rewrite it so that it leads to the appropriate place.
709  if (Scope.isNormalCleanup() && HasPrebranchedFallthrough && !IsActive) {
710  llvm::BasicBlock *prebranchDest;
711 
712  // If the prebranch is semantically branching through the next
713  // cleanup, just forward it to the next block, leaving the
714  // insertion point in the prebranched block.
715  if (FallthroughIsBranchThrough) {
716  EHScope &enclosing = *EHStack.find(Scope.getEnclosingNormalCleanup());
717  prebranchDest = CreateNormalEntry(*this, cast<EHCleanupScope>(enclosing));
718 
719  // Otherwise, we need to make a new block. If the normal cleanup
720  // isn't being used at all, we could actually reuse the normal
721  // entry block, but this is simpler, and it avoids conflicts with
722  // dead optimistic fixup branches.
723  } else {
724  prebranchDest = createBasicBlock("forwarded-prebranch");
725  EmitBlock(prebranchDest);
726  }
727 
728  llvm::BasicBlock *normalEntry = Scope.getNormalBlock();
729  assert(normalEntry && !normalEntry->use_empty());
730 
731  ForwardPrebranchedFallthrough(FallthroughSource,
732  normalEntry, prebranchDest);
733  }
734 
735  // If we don't need the cleanup at all, we're done.
736  if (!RequiresNormalCleanup && !RequiresEHCleanup) {
737  destroyOptimisticNormalEntry(*this, Scope);
738  EHStack.popCleanup(); // safe because there are no fixups
739  assert(EHStack.getNumBranchFixups() == 0 ||
740  EHStack.hasNormalCleanups());
741  return;
742  }
743 
744  // Copy the cleanup emission data out. This uses either a stack
745  // array or malloc'd memory, depending on the size, which is
746  // behavior that SmallVector would provide, if we could use it
747  // here. Unfortunately, if you ask for a SmallVector<char>, the
748  // alignment isn't sufficient.
749  auto *CleanupSource = reinterpret_cast<char *>(Scope.getCleanupBuffer());
750  llvm::AlignedCharArray<EHScopeStack::ScopeStackAlignment, 8 * sizeof(void *)> CleanupBufferStack;
751  std::unique_ptr<char[]> CleanupBufferHeap;
752  size_t CleanupSize = Scope.getCleanupSize();
754 
755  if (CleanupSize <= sizeof(CleanupBufferStack)) {
756  memcpy(CleanupBufferStack.buffer, CleanupSource, CleanupSize);
757  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferStack.buffer);
758  } else {
759  CleanupBufferHeap.reset(new char[CleanupSize]);
760  memcpy(CleanupBufferHeap.get(), CleanupSource, CleanupSize);
761  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferHeap.get());
762  }
763 
764  EHScopeStack::Cleanup::Flags cleanupFlags;
765  if (Scope.isNormalCleanup())
766  cleanupFlags.setIsNormalCleanupKind();
767  if (Scope.isEHCleanup())
768  cleanupFlags.setIsEHCleanupKind();
769 
770  if (!RequiresNormalCleanup) {
771  destroyOptimisticNormalEntry(*this, Scope);
772  EHStack.popCleanup();
773  } else {
774  // If we have a fallthrough and no other need for the cleanup,
775  // emit it directly.
776  if (HasFallthrough && !HasPrebranchedFallthrough &&
777  !HasFixups && !HasExistingBranches) {
778 
779  destroyOptimisticNormalEntry(*this, Scope);
780  EHStack.popCleanup();
781 
782  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
783 
784  // Otherwise, the best approach is to thread everything through
785  // the cleanup block and then try to clean up after ourselves.
786  } else {
787  // Force the entry block to exist.
788  llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
789 
790  // I. Set up the fallthrough edge in.
791 
792  CGBuilderTy::InsertPoint savedInactiveFallthroughIP;
793 
794  // If there's a fallthrough, we need to store the cleanup
795  // destination index. For fall-throughs this is always zero.
796  if (HasFallthrough) {
797  if (!HasPrebranchedFallthrough)
798  Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
799 
800  // Otherwise, save and clear the IP if we don't have fallthrough
801  // because the cleanup is inactive.
802  } else if (FallthroughSource) {
803  assert(!IsActive && "source without fallthrough for active cleanup");
804  savedInactiveFallthroughIP = Builder.saveAndClearIP();
805  }
806 
807  // II. Emit the entry block. This implicitly branches to it if
808  // we have fallthrough. All the fixups and existing branches
809  // should already be branched to it.
810  EmitBlock(NormalEntry);
811 
812  // III. Figure out where we're going and build the cleanup
813  // epilogue.
814 
815  bool HasEnclosingCleanups =
816  (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
817 
818  // Compute the branch-through dest if we need it:
819  // - if there are branch-throughs threaded through the scope
820  // - if fall-through is a branch-through
821  // - if there are fixups that will be optimistically forwarded
822  // to the enclosing cleanup
823  llvm::BasicBlock *BranchThroughDest = nullptr;
824  if (Scope.hasBranchThroughs() ||
825  (FallthroughSource && FallthroughIsBranchThrough) ||
826  (HasFixups && HasEnclosingCleanups)) {
827  assert(HasEnclosingCleanups);
828  EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
829  BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
830  }
831 
832  llvm::BasicBlock *FallthroughDest = nullptr;
834 
835  // If there's exactly one branch-after and no other threads,
836  // we can route it without a switch.
837  if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
838  Scope.getNumBranchAfters() == 1) {
839  assert(!BranchThroughDest || !IsActive);
840 
841  // Clean up the possibly dead store to the cleanup dest slot.
842  llvm::Instruction *NormalCleanupDestSlot =
843  cast<llvm::Instruction>(getNormalCleanupDestSlot().getPointer());
844  if (NormalCleanupDestSlot->hasOneUse()) {
845  NormalCleanupDestSlot->user_back()->eraseFromParent();
846  NormalCleanupDestSlot->eraseFromParent();
847  NormalCleanupDest = Address::invalid();
848  }
849 
850  llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
851  InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
852 
853  // Build a switch-out if we need it:
854  // - if there are branch-afters threaded through the scope
855  // - if fall-through is a branch-after
856  // - if there are fixups that have nowhere left to go and
857  // so must be immediately resolved
858  } else if (Scope.getNumBranchAfters() ||
859  (HasFallthrough && !FallthroughIsBranchThrough) ||
860  (HasFixups && !HasEnclosingCleanups)) {
861 
862  llvm::BasicBlock *Default =
863  (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
864 
865  // TODO: base this on the number of branch-afters and fixups
866  const unsigned SwitchCapacity = 10;
867 
868  llvm::LoadInst *Load =
869  createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
870  nullptr);
871  llvm::SwitchInst *Switch =
872  llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
873 
874  InstsToAppend.push_back(Load);
875  InstsToAppend.push_back(Switch);
876 
877  // Branch-after fallthrough.
878  if (FallthroughSource && !FallthroughIsBranchThrough) {
879  FallthroughDest = createBasicBlock("cleanup.cont");
880  if (HasFallthrough)
881  Switch->addCase(Builder.getInt32(0), FallthroughDest);
882  }
883 
884  for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
885  Switch->addCase(Scope.getBranchAfterIndex(I),
886  Scope.getBranchAfterBlock(I));
887  }
888 
889  // If there aren't any enclosing cleanups, we can resolve all
890  // the fixups now.
891  if (HasFixups && !HasEnclosingCleanups)
892  ResolveAllBranchFixups(*this, Switch, NormalEntry);
893  } else {
894  // We should always have a branch-through destination in this case.
895  assert(BranchThroughDest);
896  InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
897  }
898 
899  // IV. Pop the cleanup and emit it.
900  EHStack.popCleanup();
901  assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
902 
903  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
904 
905  // Append the prepared cleanup prologue from above.
906  llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
907  for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
908  NormalExit->getInstList().push_back(InstsToAppend[I]);
909 
910  // Optimistically hope that any fixups will continue falling through.
911  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
912  I < E; ++I) {
913  BranchFixup &Fixup = EHStack.getBranchFixup(I);
914  if (!Fixup.Destination) continue;
915  if (!Fixup.OptimisticBranchBlock) {
916  createStoreInstBefore(Builder.getInt32(Fixup.DestinationIndex),
917  getNormalCleanupDestSlot(),
918  Fixup.InitialBranch);
919  Fixup.InitialBranch->setSuccessor(0, NormalEntry);
920  }
921  Fixup.OptimisticBranchBlock = NormalExit;
922  }
923 
924  // V. Set up the fallthrough edge out.
925 
926  // Case 1: a fallthrough source exists but doesn't branch to the
927  // cleanup because the cleanup is inactive.
928  if (!HasFallthrough && FallthroughSource) {
929  // Prebranched fallthrough was forwarded earlier.
930  // Non-prebranched fallthrough doesn't need to be forwarded.
931  // Either way, all we need to do is restore the IP we cleared before.
932  assert(!IsActive);
933  Builder.restoreIP(savedInactiveFallthroughIP);
934 
935  // Case 2: a fallthrough source exists and should branch to the
936  // cleanup, but we're not supposed to branch through to the next
937  // cleanup.
938  } else if (HasFallthrough && FallthroughDest) {
939  assert(!FallthroughIsBranchThrough);
940  EmitBlock(FallthroughDest);
941 
942  // Case 3: a fallthrough source exists and should branch to the
943  // cleanup and then through to the next.
944  } else if (HasFallthrough) {
945  // Everything is already set up for this.
946 
947  // Case 4: no fallthrough source exists.
948  } else {
949  Builder.ClearInsertionPoint();
950  }
951 
952  // VI. Assorted cleaning.
953 
954  // Check whether we can merge NormalEntry into a single predecessor.
955  // This might invalidate (non-IR) pointers to NormalEntry.
956  llvm::BasicBlock *NewNormalEntry =
957  SimplifyCleanupEntry(*this, NormalEntry);
958 
959  // If it did invalidate those pointers, and NormalEntry was the same
960  // as NormalExit, go back and patch up the fixups.
961  if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
962  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
963  I < E; ++I)
964  EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
965  }
966  }
967 
968  assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
969 
970  // Emit the EH cleanup if required.
971  if (RequiresEHCleanup) {
972  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
973 
974  EmitBlock(EHEntry);
975 
976  llvm::BasicBlock *NextAction = getEHDispatchBlock(EHParent);
977 
978  // Push a terminate scope or cleanupendpad scope around the potentially
979  // throwing cleanups. For funclet EH personalities, the cleanupendpad models
980  // program termination when cleanups throw.
981  bool PushedTerminate = false;
982  SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
983  CurrentFuncletPad);
984  llvm::CleanupPadInst *CPI = nullptr;
985 
986  const EHPersonality &Personality = EHPersonality::get(*this);
987  if (Personality.usesFuncletPads()) {
988  llvm::Value *ParentPad = CurrentFuncletPad;
989  if (!ParentPad)
990  ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
991  CurrentFuncletPad = CPI = Builder.CreateCleanupPad(ParentPad);
992  }
993 
994  // Non-MSVC personalities need to terminate when an EH cleanup throws.
995  if (!Personality.isMSVCPersonality()) {
996  EHStack.pushTerminate();
997  PushedTerminate = true;
998  }
999 
1000  // We only actually emit the cleanup code if the cleanup is either
1001  // active or was used before it was deactivated.
1002  if (EHActiveFlag.isValid() || IsActive) {
1003  cleanupFlags.setIsForEHCleanup();
1004  EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
1005  }
1006 
1007  if (CPI)
1008  Builder.CreateCleanupRet(CPI, NextAction);
1009  else
1010  Builder.CreateBr(NextAction);
1011 
1012  // Leave the terminate scope.
1013  if (PushedTerminate)
1014  EHStack.popTerminate();
1015 
1016  Builder.restoreIP(SavedIP);
1017 
1018  SimplifyCleanupEntry(*this, EHEntry);
1019  }
1020 }
1021 
1022 /// isObviouslyBranchWithoutCleanups - Return true if a branch to the
1023 /// specified destination obviously has no cleanups to run. 'false' is always
1024 /// a conservatively correct answer for this method.
1026  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1027  && "stale jump destination");
1028 
1029  // Calculate the innermost active normal cleanup.
1030  EHScopeStack::stable_iterator TopCleanup =
1031  EHStack.getInnermostActiveNormalCleanup();
1032 
1033  // If we're not in an active normal cleanup scope, or if the
1034  // destination scope is within the innermost active normal cleanup
1035  // scope, we don't need to worry about fixups.
1036  if (TopCleanup == EHStack.stable_end() ||
1037  TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid
1038  return true;
1039 
1040  // Otherwise, we might need some cleanups.
1041  return false;
1042 }
1043 
1044 
1045 /// Terminate the current block by emitting a branch which might leave
1046 /// the current cleanup-protected scope. The target scope may not yet
1047 /// be known, in which case this will require a fixup.
1048 ///
1049 /// As a side-effect, this method clears the insertion point.
1051  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1052  && "stale jump destination");
1053 
1054  if (!HaveInsertPoint())
1055  return;
1056 
1057  // Create the branch.
1058  llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
1059 
1060  // Calculate the innermost active normal cleanup.
1062  TopCleanup = EHStack.getInnermostActiveNormalCleanup();
1063 
1064  // If we're not in an active normal cleanup scope, or if the
1065  // destination scope is within the innermost active normal cleanup
1066  // scope, we don't need to worry about fixups.
1067  if (TopCleanup == EHStack.stable_end() ||
1068  TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
1069  Builder.ClearInsertionPoint();
1070  return;
1071  }
1072 
1073  // If we can't resolve the destination cleanup scope, just add this
1074  // to the current cleanup scope as a branch fixup.
1075  if (!Dest.getScopeDepth().isValid()) {
1076  BranchFixup &Fixup = EHStack.addBranchFixup();
1077  Fixup.Destination = Dest.getBlock();
1078  Fixup.DestinationIndex = Dest.getDestIndex();
1079  Fixup.InitialBranch = BI;
1080  Fixup.OptimisticBranchBlock = nullptr;
1081 
1082  Builder.ClearInsertionPoint();
1083  return;
1084  }
1085 
1086  // Otherwise, thread through all the normal cleanups in scope.
1087 
1088  // Store the index at the start.
1089  llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
1090  createStoreInstBefore(Index, getNormalCleanupDestSlot(), BI);
1091 
1092  // Adjust BI to point to the first cleanup block.
1093  {
1095  cast<EHCleanupScope>(*EHStack.find(TopCleanup));
1096  BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
1097  }
1098 
1099  // Add this destination to all the scopes involved.
1100  EHScopeStack::stable_iterator I = TopCleanup;
1102  if (E.strictlyEncloses(I)) {
1103  while (true) {
1104  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
1105  assert(Scope.isNormalCleanup());
1106  I = Scope.getEnclosingNormalCleanup();
1107 
1108  // If this is the last cleanup we're propagating through, tell it
1109  // that there's a resolved jump moving through it.
1110  if (!E.strictlyEncloses(I)) {
1111  Scope.addBranchAfter(Index, Dest.getBlock());
1112  break;
1113  }
1114 
1115  // Otherwise, tell the scope that there's a jump propagating
1116  // through it. If this isn't new information, all the rest of
1117  // the work has been done before.
1118  if (!Scope.addBranchThrough(Dest.getBlock()))
1119  break;
1120  }
1121  }
1122 
1123  Builder.ClearInsertionPoint();
1124 }
1125 
1128  // If we needed a normal block for any reason, that counts.
1129  if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
1130  return true;
1131 
1132  // Check whether any enclosed cleanups were needed.
1134  I = EHStack.getInnermostNormalCleanup();
1135  I != C; ) {
1136  assert(C.strictlyEncloses(I));
1137  EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
1138  if (S.getNormalBlock()) return true;
1139  I = S.getEnclosingNormalCleanup();
1140  }
1141 
1142  return false;
1143 }
1144 
1145 static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
1147  // If we needed an EH block for any reason, that counts.
1148  if (EHStack.find(cleanup)->hasEHBranches())
1149  return true;
1150 
1151  // Check whether any enclosed cleanups were needed.
1153  i = EHStack.getInnermostEHScope(); i != cleanup; ) {
1154  assert(cleanup.strictlyEncloses(i));
1155 
1156  EHScope &scope = *EHStack.find(i);
1157  if (scope.hasEHBranches())
1158  return true;
1159 
1160  i = scope.getEnclosingEHScope();
1161  }
1162 
1163  return false;
1164 }
1165 
1169 };
1170 
1171 /// The given cleanup block is changing activation state. Configure a
1172 /// cleanup variable if necessary.
1173 ///
1174 /// It would be good if we had some way of determining if there were
1175 /// extra uses *after* the change-over point.
1179  llvm::Instruction *dominatingIP) {
1180  EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
1181 
1182  // We always need the flag if we're activating the cleanup in a
1183  // conditional context, because we have to assume that the current
1184  // location doesn't necessarily dominate the cleanup's code.
1185  bool isActivatedInConditional =
1186  (kind == ForActivation && CGF.isInConditionalBranch());
1187 
1188  bool needFlag = false;
1189 
1190  // Calculate whether the cleanup was used:
1191 
1192  // - as a normal cleanup
1193  if (Scope.isNormalCleanup() &&
1194  (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
1196  needFlag = true;
1197  }
1198 
1199  // - as an EH cleanup
1200  if (Scope.isEHCleanup() &&
1201  (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
1202  Scope.setTestFlagInEHCleanup();
1203  needFlag = true;
1204  }
1205 
1206  // If it hasn't yet been used as either, we're done.
1207  if (!needFlag) return;
1208 
1209  Address var = Scope.getActiveFlag();
1210  if (!var.isValid()) {
1211  var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), CharUnits::One(),
1212  "cleanup.isactive");
1213  Scope.setActiveFlag(var);
1214 
1215  assert(dominatingIP && "no existing variable and no dominating IP!");
1216 
1217  // Initialize to true or false depending on whether it was
1218  // active up to this point.
1219  llvm::Constant *value = CGF.Builder.getInt1(kind == ForDeactivation);
1220 
1221  // If we're in a conditional block, ignore the dominating IP and
1222  // use the outermost conditional branch.
1223  if (CGF.isInConditionalBranch()) {
1224  CGF.setBeforeOutermostConditional(value, var);
1225  } else {
1226  createStoreInstBefore(value, var, dominatingIP);
1227  }
1228  }
1229 
1230  CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
1231 }
1232 
1233 /// Activate a cleanup that was created in an inactivated state.
1235  llvm::Instruction *dominatingIP) {
1236  assert(C != EHStack.stable_end() && "activating bottom of stack?");
1237  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1238  assert(!Scope.isActive() && "double activation");
1239 
1240  SetupCleanupBlockActivation(*this, C, ForActivation, dominatingIP);
1241 
1242  Scope.setActive(true);
1243 }
1244 
1245 /// Deactive a cleanup that was created in an active state.
1247  llvm::Instruction *dominatingIP) {
1248  assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
1249  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1250  assert(Scope.isActive() && "double deactivation");
1251 
1252  // If it's the top of the stack, just pop it, but do so only if it belongs
1253  // to the current RunCleanupsScope.
1254  if (C == EHStack.stable_begin() &&
1255  CurrentCleanupScopeDepth.strictlyEncloses(C)) {
1256  // If it's a normal cleanup, we need to pretend that the
1257  // fallthrough is unreachable.
1258  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1259  PopCleanupBlock();
1260  Builder.restoreIP(SavedIP);
1261  return;
1262  }
1263 
1264  // Otherwise, follow the general case.
1265  SetupCleanupBlockActivation(*this, C, ForDeactivation, dominatingIP);
1266 
1267  Scope.setActive(false);
1268 }
1269 
1271  if (!NormalCleanupDest.isValid())
1272  NormalCleanupDest =
1273  CreateDefaultAlignTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
1274  return NormalCleanupDest;
1275 }
1276 
1277 /// Emits all the code to cause the given temporary to be cleaned up.
1279  QualType TempType,
1280  Address Ptr) {
1281  pushDestroy(NormalAndEHCleanup, Ptr, TempType, destroyCXXObject,
1282  /*useEHCleanup*/ true);
1283 }
bool isAggregate() const
Definition: CGValue.h:54
const llvm::DataLayout & getDataLayout() const
void pushTerminate()
Push a terminate handler on the stack.
Definition: CGCleanup.cpp:259
static llvm::BasicBlock * CreateNormalEntry(CodeGenFunction &CGF, EHCleanupScope &Scope)
Definition: CGCleanup.cpp:512
EHScopeStack::stable_iterator getEnclosingEHScope() const
Definition: CGCleanup.h:138
void ActivateCleanupBlock(EHScopeStack::stable_iterator Cleanup, llvm::Instruction *DominatingIP)
ActivateCleanupBlock - Activates an initially-inactive cleanup.
Definition: CGCleanup.cpp:1234
A (possibly-)qualified type.
Definition: Type.h:642
bool usesFuncletPads() const
Does this personality use landingpads or the family of pad instructions designed to form funclets...
Definition: CGCleanup.h:634
static llvm::LoadInst * createLoadInstBefore(Address addr, const Twine &name, llvm::Instruction *beforeInst)
Definition: CGCleanup.cpp:317
static void destroyOptimisticNormalEntry(CodeGenFunction &CGF, EHCleanupScope &scope)
We don&#39;t need a normal entry block for the given cleanup.
Definition: CGCleanup.cpp:611
llvm::BasicBlock * getCachedEHDispatchBlock() const
Definition: CGCleanup.h:124
bool HaveInsertPoint() const
HaveInsertPoint - True if an insertion point is defined.
void initFullExprCleanupWithFlag(Address ActiveFlag)
Definition: CGCleanup.cpp:299
static stable_iterator stable_end()
Create a stable reference to the bottom of the EH stack.
Definition: EHScopeStack.h:384
tooling::Replacements cleanup(const FormatStyle &Style, StringRef Code, ArrayRef< tooling::Range > Ranges, StringRef FileName="<stdin>")
Clean up any erroneous/redundant code in the given Ranges in Code.
Definition: Format.cpp:2219
bool hasEHBranches() const
Definition: CGCleanup.h:132
static llvm::SwitchInst * TransitionToCleanupSwitch(CodeGenFunction &CGF, llvm::BasicBlock *Block)
Transitions the terminator of the given exit-block of a cleanup to be a cleanup switch.
Definition: CGCleanup.cpp:365
iterator find(stable_iterator save) const
Turn a stable reference to a scope depth into a unstable pointer to the EH stack. ...
Definition: CGCleanup.h:591
stable_iterator stable_begin() const
Create a stable reference to the top of the EH stack.
Definition: EHScopeStack.h:379
llvm::BasicBlock * getNormalBlock() const
Definition: CGCleanup.h:313
unsigned getNumFilters() const
Definition: CGCleanup.h:461
static bool needsSaving(llvm::Value *value)
Answer whether the given value needs extra work to be saved.
bool empty() const
Determines whether the exception-scopes stack is empty.
Definition: EHScopeStack.h:345
static void EmitCleanup(CodeGenFunction &CGF, EHScopeStack::Cleanup *Fn, EHScopeStack::Cleanup::Flags flags, Address ActiveFlag)
Definition: CGCleanup.cpp:562
llvm::Value * getPointer() const
Definition: Address.h:38
iterator begin() const
Returns an iterator pointing to the innermost EH scope.
Definition: CGCleanup.h:567
A protected scope for zero-cost EH handling.
Definition: CGCleanup.h:44
A scope which attempts to handle some, possibly all, types of exceptions.
Definition: CGCleanup.h:148
A jump destination is an abstract label, branching to which may require a jump out through normal cle...
bool addBranchThrough(llvm::BasicBlock *Block)
Add a branch-through to this cleanup scope.
Definition: CGCleanup.h:410
bool isObviouslyBranchWithoutCleanups(JumpDest Dest) const
isObviouslyBranchWithoutCleanups - Return true if a branch to the specified destination obviously has...
Definition: CGCleanup.cpp:1025
static size_t getSizeForCleanupSize(size_t Size)
Gets the size required for a lazy cleanup scope with the given cleanup-data requirements.
Definition: CGCleanup.h:280
An exceptions scope which calls std::terminate if any exception reaches it.
Definition: CGCleanup.h:480
bool isMSVCPersonality() const
Definition: CGCleanup.h:638
CodeGenFunction - This class organizes the per-function state that is used while generating LLVM code...
ForActivation_t
Definition: CGCleanup.cpp:1166
bool shouldTestFlagInNormalCleanup() const
Definition: CGCleanup.h:336
Denotes a cleanup that should run when a scope is exited using exceptional control flow (a throw stat...
Definition: EHScopeStack.h:81
static const EHPersonality & get(CodeGenModule &CGM, const FunctionDecl *FD)
A metaprogramming class for ensuring that a value will dominate an arbitrary position in a function...
Definition: EHScopeStack.h:66
unsigned getNumBranchFixups() const
Definition: EHScopeStack.h:402
class EHCatchScope * pushCatch(unsigned NumHandlers)
Push a set of catch handlers on the stack.
Definition: CGCleanup.cpp:251
BranchFixup & getBranchFixup(unsigned I)
Definition: EHScopeStack.h:403
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
void setNormalBlock(llvm::BasicBlock *BB)
Definition: CGCleanup.h:314
CharUnits getAlignment() const
Return the alignment of this pointer.
Definition: Address.h:67
bool isComplex() const
Definition: CGValue.h:53
bool hasNormalCleanups() const
Determines whether there are any normal cleanups on the stack.
Definition: EHScopeStack.h:350
bool containsOnlyLifetimeMarkers(stable_iterator Old) const
Definition: CGCleanup.cpp:148
Scope - A scope is a transient data structure that is used while parsing the program.
Definition: Scope.h:40
A stack of scopes which respond to exceptions, including cleanups and catch blocks.
Definition: EHScopeStack.h:100
llvm::BasicBlock * createBasicBlock(const Twine &name="", llvm::Function *parent=nullptr, llvm::BasicBlock *before=nullptr)
createBasicBlock - Create an LLVM basic block.
Denotes a cleanup that should run when a scope is exited using normal control flow (falling off the e...
Definition: EHScopeStack.h:85
bool strictlyEncloses(stable_iterator I) const
Returns true if this scope strictly encloses I: that is, if it encloses I and is not I...
Definition: EHScopeStack.h:130
void popFilter()
Pops an exceptions filter off the stack.
Definition: CGCleanup.cpp:242
llvm::AllocaInst * CreateTempAlloca(llvm::Type *Ty, const Twine &Name="tmp", llvm::Value *ArraySize=nullptr)
CreateTempAlloca - This creates an alloca and inserts it into the entry block if ArraySize is nullptr...
Definition: CGExpr.cpp:106
Address NormalCleanupDest
i32s containing the indexes of the cleanup destinations.
static bool IsUsedAsEHCleanup(EHScopeStack &EHStack, EHScopeStack::stable_iterator cleanup)
Definition: CGCleanup.cpp:1145
static size_t getSizeForNumHandlers(unsigned N)
Definition: CGCleanup.h:178
Address getAggregateAddress() const
getAggregateAddr() - Return the Value* of the address of the aggregate.
Definition: CGValue.h:71
bool isValid() const
Definition: Address.h:36
static CharUnits One()
One - Construct a CharUnits quantity of one.
Definition: CharUnits.h:58
unsigned getFixupDepth() const
Definition: CGCleanup.h:347
std::pair< llvm::Value *, llvm::Value * > ComplexPairTy
static void createStoreInstBefore(llvm::Value *value, Address addr, llvm::Instruction *beforeInst)
Definition: CGCleanup.cpp:311
unsigned getNumBranchAfters() const
Return the number of unique branch-afters on this scope.
Definition: CGCleanup.h:381
RValue - This trivial value class is used to represent the result of an expression that is evaluated...
Definition: CGValue.h:39
static void ResolveAllBranchFixups(CodeGenFunction &CGF, llvm::SwitchInst *Switch, llvm::BasicBlock *CleanupEntry)
All the branch fixups on the EH stack have propagated out past the outermost normal cleanup; resolve ...
Definition: CGCleanup.cpp:327
llvm::BranchInst * InitialBranch
The initial branch of the fixup.
Definition: EHScopeStack.h:53
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
Address CreateDefaultAlignTempAlloca(llvm::Type *Ty, const Twine &Name="tmp")
CreateDefaultAlignedTempAlloca - This creates an alloca with the default ABI alignment of the given L...
Definition: CGExpr.cpp:119
EHScopeStack::stable_iterator getScopeDepth() const
void clearFixups()
Clears the branch-fixups list.
Definition: EHScopeStack.h:415
static Address invalid()
Definition: Address.h:35
stable_iterator getInnermostNormalCleanup() const
Returns the innermost normal cleanup on the stack, or stable_end() if there are no normal cleanups...
Definition: EHScopeStack.h:356
std::pair< llvm::Value *, llvm::Value * > getComplexVal() const
getComplexVal - Return the real/imag components of this complex value.
Definition: CGValue.h:66
size_t getCleanupSize() const
Definition: CGCleanup.h:352
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
llvm::ConstantInt * getBranchAfterIndex(unsigned I) const
Definition: CGCleanup.h:390
void ResolveBranchFixups(llvm::BasicBlock *Target)
Definition: CGCleanup.cpp:385
void setActiveFlag(Address Var)
Definition: CGCleanup.h:328
stable_iterator stabilize(iterator it) const
Translates an iterator into a stable_iterator.
Definition: CGCleanup.h:598
bool encloses(stable_iterator I) const
Returns true if this scope encloses I.
Definition: EHScopeStack.h:124
size_t getAllocatedSize() const
Definition: CGCleanup.h:284
llvm::BasicBlock * OptimisticBranchBlock
The block containing the terminator which needs to be modified into a switch if this fixup is resolve...
Definition: EHScopeStack.h:41
void popCleanup()
Pops a cleanup scope off the stack. This is private to CGCleanup.cpp.
Definition: CGCleanup.cpp:209
The l-value was considered opaque, so the alignment was determined from a type.
void PopCleanupBlocks(EHScopeStack::stable_iterator OldCleanupStackSize, std::initializer_list< llvm::Value **> ValuesToReload={})
Takes the old cleanup stack size and emits the cleanup blocks that have been added.
Definition: CGCleanup.cpp:424
llvm::BasicBlock * Destination
The ultimate destination of the branch.
Definition: EHScopeStack.h:47
Kind
A saved depth on the scope stack.
Definition: EHScopeStack.h:107
Represents a C++ temporary.
Definition: ExprCXX.h:1185
llvm::BasicBlock * getUnreachableBlock()
void setBeforeOutermostConditional(llvm::Value *value, Address addr)
void DeactivateCleanupBlock(EHScopeStack::stable_iterator Cleanup, llvm::Instruction *DominatingIP)
DeactivateCleanupBlock - Deactivates the given cleanup block.
Definition: CGCleanup.cpp:1246
EHScopeStack::stable_iterator getEnclosingNormalCleanup() const
Definition: CGCleanup.h:348
void EmitCXXTemporary(const CXXTemporary *Temporary, QualType TempType, Address Ptr)
Emits all the code to cause the given temporary to be cleaned up.
Definition: CGCleanup.cpp:1278
An aligned address.
Definition: Address.h:25
unsigned DestinationIndex
The destination index value.
Definition: EHScopeStack.h:50
__DEVICE__ void * memcpy(void *__a, const void *__b, size_t __c)
virtual void Emit(CodeGenFunction &CGF, Flags flags)=0
Emit the cleanup.
static size_t getSizeForNumFilters(unsigned numFilters)
Definition: CGCleanup.h:457
static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack, EHScopeStack::stable_iterator C)
Definition: CGCleanup.cpp:1126
static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit, llvm::BasicBlock *From, llvm::BasicBlock *To)
Definition: CGCleanup.cpp:587
llvm::Value * getScalarVal() const
getScalarVal() - Return the Value* of this scalar value.
Definition: CGValue.h:59
class EHFilterScope * pushFilter(unsigned NumFilters)
Push an exceptions filter on the stack.
Definition: CGCleanup.cpp:234
Dataflow Directional Tag Classes.
static RValue getComplex(llvm::Value *V1, llvm::Value *V2)
Definition: CGValue.h:93
void popNullFixups()
Pops lazily-removed fixups from the end of the list.
Definition: CGCleanup.cpp:270
bool shouldTestFlagInEHCleanup() const
Definition: CGCleanup.h:343
void addBranchAfter(llvm::ConstantInt *Index, llvm::BasicBlock *Block)
Add a branch-after to this cleanup scope.
Definition: CGCleanup.h:373
Address CreateStructGEP(Address Addr, unsigned Index, CharUnits Offset, const llvm::Twine &Name="")
Definition: CGBuilder.h:172
static llvm::BasicBlock * SimplifyCleanupEntry(CodeGenFunction &CGF, llvm::BasicBlock *Entry)
Attempts to reduce a cleanup&#39;s entry block to a fallthrough.
Definition: CGCleanup.cpp:528
bool isInConditionalBranch() const
isInConditionalBranch - Return true if we&#39;re currently emitting one branch or the other of a conditio...
llvm::LoadInst * CreateLoad(Address Addr, const llvm::Twine &Name="")
Definition: CGBuilder.h:70
Header for data within LifetimeExtendedCleanupStack.
llvm::StoreInst * CreateStore(llvm::Value *Val, Address Addr, bool IsVolatile=false)
Definition: CGBuilder.h:108
static void SetupCleanupBlockActivation(CodeGenFunction &CGF, EHScopeStack::stable_iterator C, ForActivation_t kind, llvm::Instruction *dominatingIP)
The given cleanup block is changing activation state.
Definition: CGCleanup.cpp:1176
stable_iterator getInnermostActiveNormalCleanup() const
Definition: CGCleanup.cpp:174
llvm::Value * getAggregatePointer() const
Definition: CGValue.h:76
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
EmitBlock - Emit the given block.
Definition: CGStmt.cpp:445
bool hasBranches() const
True if this cleanup scope has any branch-afters or branch-throughs.
Definition: CGCleanup.h:360
Address getActiveFlag() const
Definition: CGCleanup.h:325
The exceptions personality for a function.
Definition: CGCleanup.h:604
unsigned kind
All of the diagnostics that can be emitted by the frontend.
Definition: DiagnosticIDs.h:61
llvm::BasicBlock * getBranchAfterBlock(unsigned I) const
Definition: CGCleanup.h:385
A cleanup scope which generates the cleanup blocks lazily.
Definition: CGCleanup.h:233
stable_iterator getInnermostEHScope() const
Definition: EHScopeStack.h:361
bool hasBranchThroughs() const
Determines if this cleanup scope has any branch throughs.
Definition: CGCleanup.h:415
An exceptions scope which filters exceptions thrown through it.
Definition: CGCleanup.h:438
static RValue get(llvm::Value *V)
Definition: CGValue.h:86
void EmitBranchThroughCleanup(JumpDest Dest)
EmitBranchThroughCleanup - Emit a branch from the current insert block through the normal cleanup han...
Definition: CGCleanup.cpp:1050
static RValue getAggregate(Address addr, bool isVolatile=false)
Definition: CGValue.h:107
Information for lazily generating a cleanup.
Definition: EHScopeStack.h:147
A non-stable pointer into the scope stack.
Definition: CGCleanup.h:503
void PopCleanupBlock(bool FallThroughIsBranchThrough=false)
PopCleanupBlock - Will pop the cleanup entry on the stack and process all branch fixups.
Definition: CGCleanup.cpp:651
bool isScalar() const
Definition: CGValue.h:52
static OMPLinearClause * Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation LParenLoc, OpenMPLinearClauseKind Modifier, SourceLocation ModifierLoc, SourceLocation ColonLoc, SourceLocation EndLoc, ArrayRef< Expr *> VL, ArrayRef< Expr *> PL, ArrayRef< Expr *> IL, Expr *Step, Expr *CalcStep, Stmt *PreInit, Expr *PostUpdate)
Creates clause with a list of variables VL and a linear step Step.