clang  9.0.0svn
CGCleanup.cpp
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1 //===--- CGCleanup.cpp - Bookkeeping and code emission for cleanups -------===//
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 contains code dealing with the IR generation for cleanups
10 // and related information.
11 //
12 // A "cleanup" is a piece of code which needs to be executed whenever
13 // control transfers out of a particular scope. This can be
14 // conditionalized to occur only on exceptional control flow, only on
15 // normal control flow, or both.
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #include "CGCleanup.h"
20 #include "CodeGenFunction.h"
21 #include "llvm/Support/SaveAndRestore.h"
22 
23 using namespace clang;
24 using namespace CodeGen;
25 
27  if (rv.isScalar())
29  if (rv.isAggregate())
31  return true;
32 }
33 
36  if (rv.isScalar()) {
37  llvm::Value *V = rv.getScalarVal();
38 
39  // These automatically dominate and don't need to be saved.
41  return saved_type(V, ScalarLiteral);
42 
43  // Everything else needs an alloca.
44  Address addr =
45  CGF.CreateDefaultAlignTempAlloca(V->getType(), "saved-rvalue");
46  CGF.Builder.CreateStore(V, addr);
47  return saved_type(addr.getPointer(), ScalarAddress);
48  }
49 
50  if (rv.isComplex()) {
52  llvm::Type *ComplexTy =
53  llvm::StructType::get(V.first->getType(), V.second->getType());
54  Address addr = CGF.CreateDefaultAlignTempAlloca(ComplexTy, "saved-complex");
55  CGF.Builder.CreateStore(V.first,
56  CGF.Builder.CreateStructGEP(addr, 0, CharUnits()));
58  CGF.CGM.getDataLayout().getTypeAllocSize(V.first->getType()));
59  CGF.Builder.CreateStore(V.second,
60  CGF.Builder.CreateStructGEP(addr, 1, offset));
61  return saved_type(addr.getPointer(), ComplexAddress);
62  }
63 
64  assert(rv.isAggregate());
65  Address V = rv.getAggregateAddress(); // TODO: volatile?
66  if (!DominatingLLVMValue::needsSaving(V.getPointer()))
67  return saved_type(V.getPointer(), AggregateLiteral,
68  V.getAlignment().getQuantity());
69 
70  Address addr =
71  CGF.CreateTempAlloca(V.getType(), CGF.getPointerAlign(), "saved-rvalue");
72  CGF.Builder.CreateStore(V.getPointer(), addr);
73  return saved_type(addr.getPointer(), AggregateAddress,
74  V.getAlignment().getQuantity());
75 }
76 
77 /// Given a saved r-value produced by SaveRValue, perform the code
78 /// necessary to restore it to usability at the current insertion
79 /// point.
81  auto getSavingAddress = [&](llvm::Value *value) {
82  auto alignment = cast<llvm::AllocaInst>(value)->getAlignment();
83  return Address(value, CharUnits::fromQuantity(alignment));
84  };
85  switch (K) {
86  case ScalarLiteral:
87  return RValue::get(Value);
88  case ScalarAddress:
89  return RValue::get(CGF.Builder.CreateLoad(getSavingAddress(Value)));
90  case AggregateLiteral:
92  case AggregateAddress: {
93  auto addr = CGF.Builder.CreateLoad(getSavingAddress(Value));
95  }
96  case ComplexAddress: {
97  Address address = getSavingAddress(Value);
98  llvm::Value *real = CGF.Builder.CreateLoad(
99  CGF.Builder.CreateStructGEP(address, 0, CharUnits()));
101  CGF.CGM.getDataLayout().getTypeAllocSize(real->getType()));
102  llvm::Value *imag = CGF.Builder.CreateLoad(
103  CGF.Builder.CreateStructGEP(address, 1, offset));
104  return RValue::getComplex(real, imag);
105  }
106  }
107 
108  llvm_unreachable("bad saved r-value kind");
109 }
110 
111 /// Push an entry of the given size onto this protected-scope stack.
112 char *EHScopeStack::allocate(size_t Size) {
113  Size = llvm::alignTo(Size, ScopeStackAlignment);
114  if (!StartOfBuffer) {
115  unsigned Capacity = 1024;
116  while (Capacity < Size) Capacity *= 2;
117  StartOfBuffer = new char[Capacity];
118  StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
119  } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
120  unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
121  unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
122 
123  unsigned NewCapacity = CurrentCapacity;
124  do {
125  NewCapacity *= 2;
126  } while (NewCapacity < UsedCapacity + Size);
127 
128  char *NewStartOfBuffer = new char[NewCapacity];
129  char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
130  char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
131  memcpy(NewStartOfData, StartOfData, UsedCapacity);
132  delete [] StartOfBuffer;
133  StartOfBuffer = NewStartOfBuffer;
134  EndOfBuffer = NewEndOfBuffer;
135  StartOfData = NewStartOfData;
136  }
137 
138  assert(StartOfBuffer + Size <= StartOfData);
139  StartOfData -= Size;
140  return StartOfData;
141 }
142 
143 void EHScopeStack::deallocate(size_t Size) {
144  StartOfData += llvm::alignTo(Size, ScopeStackAlignment);
145 }
146 
148  EHScopeStack::stable_iterator Old) const {
149  for (EHScopeStack::iterator it = begin(); stabilize(it) != Old; it++) {
150  EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*it);
151  if (!cleanup || !cleanup->isLifetimeMarker())
152  return false;
153  }
154 
155  return true;
156 }
157 
159  for (stable_iterator si = getInnermostEHScope(); si != stable_end(); ) {
160  // Skip lifetime markers.
161  if (auto *cleanup = dyn_cast<EHCleanupScope>(&*find(si)))
162  if (cleanup->isLifetimeMarker()) {
163  si = cleanup->getEnclosingEHScope();
164  continue;
165  }
166  return true;
167  }
168 
169  return false;
170 }
171 
175  si != se; ) {
176  EHCleanupScope &cleanup = cast<EHCleanupScope>(*find(si));
177  if (cleanup.isActive()) return si;
178  si = cleanup.getEnclosingNormalCleanup();
179  }
180  return stable_end();
181 }
182 
183 
184 void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
185  char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
186  bool IsNormalCleanup = Kind & NormalCleanup;
187  bool IsEHCleanup = Kind & EHCleanup;
188  bool IsActive = !(Kind & InactiveCleanup);
189  bool IsLifetimeMarker = Kind & LifetimeMarker;
191  new (Buffer) EHCleanupScope(IsNormalCleanup,
192  IsEHCleanup,
193  IsActive,
194  Size,
195  BranchFixups.size(),
196  InnermostNormalCleanup,
197  InnermostEHScope);
198  if (IsNormalCleanup)
199  InnermostNormalCleanup = stable_begin();
200  if (IsEHCleanup)
201  InnermostEHScope = stable_begin();
202  if (IsLifetimeMarker)
203  Scope->setLifetimeMarker();
204 
205  return Scope->getCleanupBuffer();
206 }
207 
209  assert(!empty() && "popping exception stack when not empty");
210 
211  assert(isa<EHCleanupScope>(*begin()));
212  EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
213  InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
214  InnermostEHScope = Cleanup.getEnclosingEHScope();
215  deallocate(Cleanup.getAllocatedSize());
216 
217  // Destroy the cleanup.
218  Cleanup.Destroy();
219 
220  // Check whether we can shrink the branch-fixups stack.
221  if (!BranchFixups.empty()) {
222  // If we no longer have any normal cleanups, all the fixups are
223  // complete.
224  if (!hasNormalCleanups())
225  BranchFixups.clear();
226 
227  // Otherwise we can still trim out unnecessary nulls.
228  else
229  popNullFixups();
230  }
231 }
232 
234  assert(getInnermostEHScope() == stable_end());
235  char *buffer = allocate(EHFilterScope::getSizeForNumFilters(numFilters));
236  EHFilterScope *filter = new (buffer) EHFilterScope(numFilters);
237  InnermostEHScope = stable_begin();
238  return filter;
239 }
240 
242  assert(!empty() && "popping exception stack when not empty");
243 
244  EHFilterScope &filter = cast<EHFilterScope>(*begin());
246 
247  InnermostEHScope = filter.getEnclosingEHScope();
248 }
249 
250 EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) {
251  char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers));
252  EHCatchScope *scope =
253  new (buffer) EHCatchScope(numHandlers, InnermostEHScope);
254  InnermostEHScope = stable_begin();
255  return scope;
256 }
257 
259  char *Buffer = allocate(EHTerminateScope::getSize());
260  new (Buffer) EHTerminateScope(InnermostEHScope);
261  InnermostEHScope = stable_begin();
262 }
263 
264 /// Remove any 'null' fixups on the stack. However, we can't pop more
265 /// fixups than the fixup depth on the innermost normal cleanup, or
266 /// else fixups that we try to add to that cleanup will end up in the
267 /// wrong place. We *could* try to shrink fixup depths, but that's
268 /// actually a lot of work for little benefit.
270  // We expect this to only be called when there's still an innermost
271  // normal cleanup; otherwise there really shouldn't be any fixups.
272  assert(hasNormalCleanups());
273 
274  EHScopeStack::iterator it = find(InnermostNormalCleanup);
275  unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
276  assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
277 
278  while (BranchFixups.size() > MinSize &&
279  BranchFixups.back().Destination == nullptr)
280  BranchFixups.pop_back();
281 }
282 
284  // Create a variable to decide whether the cleanup needs to be run.
285  Address active = CreateTempAllocaWithoutCast(
286  Builder.getInt1Ty(), CharUnits::One(), "cleanup.cond");
287 
288  // Initialize it to false at a site that's guaranteed to be run
289  // before each evaluation.
290  setBeforeOutermostConditional(Builder.getFalse(), active);
291 
292  // Initialize it to true at the current location.
293  Builder.CreateStore(Builder.getTrue(), active);
294 
295  return active;
296 }
297 
299  // Set that as the active flag in the cleanup.
300  EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
301  assert(!cleanup.hasActiveFlag() && "cleanup already has active flag?");
302  cleanup.setActiveFlag(ActiveFlag);
303 
304  if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
305  if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
306 }
307 
308 void EHScopeStack::Cleanup::anchor() {}
309 
310 static void createStoreInstBefore(llvm::Value *value, Address addr,
311  llvm::Instruction *beforeInst) {
312  auto store = new llvm::StoreInst(value, addr.getPointer(), beforeInst);
313  store->setAlignment(addr.getAlignment().getQuantity());
314 }
315 
316 static llvm::LoadInst *createLoadInstBefore(Address addr, const Twine &name,
317  llvm::Instruction *beforeInst) {
318  auto load = new llvm::LoadInst(addr.getPointer(), name, beforeInst);
319  load->setAlignment(addr.getAlignment().getQuantity());
320  return load;
321 }
322 
323 /// All the branch fixups on the EH stack have propagated out past the
324 /// outermost normal cleanup; resolve them all by adding cases to the
325 /// given switch instruction.
327  llvm::SwitchInst *Switch,
328  llvm::BasicBlock *CleanupEntry) {
329  llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
330 
331  for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
332  // Skip this fixup if its destination isn't set.
333  BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
334  if (Fixup.Destination == nullptr) continue;
335 
336  // If there isn't an OptimisticBranchBlock, then InitialBranch is
337  // still pointing directly to its destination; forward it to the
338  // appropriate cleanup entry. This is required in the specific
339  // case of
340  // { std::string s; goto lbl; }
341  // lbl:
342  // i.e. where there's an unresolved fixup inside a single cleanup
343  // entry which we're currently popping.
344  if (Fixup.OptimisticBranchBlock == nullptr) {
345  createStoreInstBefore(CGF.Builder.getInt32(Fixup.DestinationIndex),
347  Fixup.InitialBranch);
348  Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
349  }
350 
351  // Don't add this case to the switch statement twice.
352  if (!CasesAdded.insert(Fixup.Destination).second)
353  continue;
354 
355  Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
356  Fixup.Destination);
357  }
358 
359  CGF.EHStack.clearFixups();
360 }
361 
362 /// Transitions the terminator of the given exit-block of a cleanup to
363 /// be a cleanup switch.
364 static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
365  llvm::BasicBlock *Block) {
366  // If it's a branch, turn it into a switch whose default
367  // destination is its original target.
368  llvm::Instruction *Term = Block->getTerminator();
369  assert(Term && "can't transition block without terminator");
370 
371  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
372  assert(Br->isUnconditional());
374  "cleanup.dest", Term);
375  llvm::SwitchInst *Switch =
376  llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
377  Br->eraseFromParent();
378  return Switch;
379  } else {
380  return cast<llvm::SwitchInst>(Term);
381  }
382 }
383 
384 void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
385  assert(Block && "resolving a null target block");
386  if (!EHStack.getNumBranchFixups()) return;
387 
388  assert(EHStack.hasNormalCleanups() &&
389  "branch fixups exist with no normal cleanups on stack");
390 
391  llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
392  bool ResolvedAny = false;
393 
394  for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
395  // Skip this fixup if its destination doesn't match.
396  BranchFixup &Fixup = EHStack.getBranchFixup(I);
397  if (Fixup.Destination != Block) continue;
398 
399  Fixup.Destination = nullptr;
400  ResolvedAny = true;
401 
402  // If it doesn't have an optimistic branch block, LatestBranch is
403  // already pointing to the right place.
404  llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
405  if (!BranchBB)
406  continue;
407 
408  // Don't process the same optimistic branch block twice.
409  if (!ModifiedOptimisticBlocks.insert(BranchBB).second)
410  continue;
411 
412  llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
413 
414  // Add a case to the switch.
415  Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
416  }
417 
418  if (ResolvedAny)
419  EHStack.popNullFixups();
420 }
421 
422 /// Pops cleanup blocks until the given savepoint is reached.
425  std::initializer_list<llvm::Value **> ValuesToReload) {
426  assert(Old.isValid());
427 
428  bool HadBranches = false;
429  while (EHStack.stable_begin() != Old) {
430  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
431  HadBranches |= Scope.hasBranches();
432 
433  // As long as Old strictly encloses the scope's enclosing normal
434  // cleanup, we're going to emit another normal cleanup which
435  // fallthrough can propagate through.
436  bool FallThroughIsBranchThrough =
438 
439  PopCleanupBlock(FallThroughIsBranchThrough);
440  }
441 
442  // If we didn't have any branches, the insertion point before cleanups must
443  // dominate the current insertion point and we don't need to reload any
444  // values.
445  if (!HadBranches)
446  return;
447 
448  // Spill and reload all values that the caller wants to be live at the current
449  // insertion point.
450  for (llvm::Value **ReloadedValue : ValuesToReload) {
451  auto *Inst = dyn_cast_or_null<llvm::Instruction>(*ReloadedValue);
452  if (!Inst)
453  continue;
454 
455  // Don't spill static allocas, they dominate all cleanups. These are created
456  // by binding a reference to a local variable or temporary.
457  auto *AI = dyn_cast<llvm::AllocaInst>(Inst);
458  if (AI && AI->isStaticAlloca())
459  continue;
460 
461  Address Tmp =
462  CreateDefaultAlignTempAlloca(Inst->getType(), "tmp.exprcleanup");
463 
464  // Find an insertion point after Inst and spill it to the temporary.
465  llvm::BasicBlock::iterator InsertBefore;
466  if (auto *Invoke = dyn_cast<llvm::InvokeInst>(Inst))
467  InsertBefore = Invoke->getNormalDest()->getFirstInsertionPt();
468  else
469  InsertBefore = std::next(Inst->getIterator());
470  CGBuilderTy(CGM, &*InsertBefore).CreateStore(Inst, Tmp);
471 
472  // Reload the value at the current insertion point.
473  *ReloadedValue = Builder.CreateLoad(Tmp);
474  }
475 }
476 
477 /// Pops cleanup blocks until the given savepoint is reached, then add the
478 /// cleanups from the given savepoint in the lifetime-extended cleanups stack.
480  EHScopeStack::stable_iterator Old, size_t OldLifetimeExtendedSize,
481  std::initializer_list<llvm::Value **> ValuesToReload) {
482  PopCleanupBlocks(Old, ValuesToReload);
483 
484  // Move our deferred cleanups onto the EH stack.
485  for (size_t I = OldLifetimeExtendedSize,
486  E = LifetimeExtendedCleanupStack.size(); I != E; /**/) {
487  // Alignment should be guaranteed by the vptrs in the individual cleanups.
488  assert((I % alignof(LifetimeExtendedCleanupHeader) == 0) &&
489  "misaligned cleanup stack entry");
490 
492  reinterpret_cast<LifetimeExtendedCleanupHeader&>(
493  LifetimeExtendedCleanupStack[I]);
494  I += sizeof(Header);
495 
496  EHStack.pushCopyOfCleanup(Header.getKind(),
497  &LifetimeExtendedCleanupStack[I],
498  Header.getSize());
499  I += Header.getSize();
500 
501  if (Header.isConditional()) {
502  Address ActiveFlag =
503  reinterpret_cast<Address &>(LifetimeExtendedCleanupStack[I]);
504  initFullExprCleanupWithFlag(ActiveFlag);
505  I += sizeof(ActiveFlag);
506  }
507  }
508  LifetimeExtendedCleanupStack.resize(OldLifetimeExtendedSize);
509 }
510 
511 static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
513  assert(Scope.isNormalCleanup());
514  llvm::BasicBlock *Entry = Scope.getNormalBlock();
515  if (!Entry) {
516  Entry = CGF.createBasicBlock("cleanup");
517  Scope.setNormalBlock(Entry);
518  }
519  return Entry;
520 }
521 
522 /// Attempts to reduce a cleanup's entry block to a fallthrough. This
523 /// is basically llvm::MergeBlockIntoPredecessor, except
524 /// simplified/optimized for the tighter constraints on cleanup blocks.
525 ///
526 /// Returns the new block, whatever it is.
527 static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
528  llvm::BasicBlock *Entry) {
529  llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
530  if (!Pred) return Entry;
531 
532  llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
533  if (!Br || Br->isConditional()) return Entry;
534  assert(Br->getSuccessor(0) == Entry);
535 
536  // If we were previously inserting at the end of the cleanup entry
537  // block, we'll need to continue inserting at the end of the
538  // predecessor.
539  bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
540  assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
541 
542  // Kill the branch.
543  Br->eraseFromParent();
544 
545  // Replace all uses of the entry with the predecessor, in case there
546  // are phis in the cleanup.
547  Entry->replaceAllUsesWith(Pred);
548 
549  // Merge the blocks.
550  Pred->getInstList().splice(Pred->end(), Entry->getInstList());
551 
552  // Kill the entry block.
553  Entry->eraseFromParent();
554 
555  if (WasInsertBlock)
556  CGF.Builder.SetInsertPoint(Pred);
557 
558  return Pred;
559 }
560 
561 static void EmitCleanup(CodeGenFunction &CGF,
564  Address ActiveFlag) {
565  // If there's an active flag, load it and skip the cleanup if it's
566  // false.
567  llvm::BasicBlock *ContBB = nullptr;
568  if (ActiveFlag.isValid()) {
569  ContBB = CGF.createBasicBlock("cleanup.done");
570  llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
571  llvm::Value *IsActive
572  = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
573  CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
574  CGF.EmitBlock(CleanupBB);
575  }
576 
577  // Ask the cleanup to emit itself.
578  Fn->Emit(CGF, flags);
579  assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
580 
581  // Emit the continuation block if there was an active flag.
582  if (ActiveFlag.isValid())
583  CGF.EmitBlock(ContBB);
584 }
585 
586 static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
587  llvm::BasicBlock *From,
588  llvm::BasicBlock *To) {
589  // Exit is the exit block of a cleanup, so it always terminates in
590  // an unconditional branch or a switch.
591  llvm::Instruction *Term = Exit->getTerminator();
592 
593  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
594  assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
595  Br->setSuccessor(0, To);
596  } else {
597  llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
598  for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
599  if (Switch->getSuccessor(I) == From)
600  Switch->setSuccessor(I, To);
601  }
602 }
603 
604 /// We don't need a normal entry block for the given cleanup.
605 /// Optimistic fixup branches can cause these blocks to come into
606 /// existence anyway; if so, destroy it.
607 ///
608 /// The validity of this transformation is very much specific to the
609 /// exact ways in which we form branches to cleanup entries.
611  EHCleanupScope &scope) {
612  llvm::BasicBlock *entry = scope.getNormalBlock();
613  if (!entry) return;
614 
615  // Replace all the uses with unreachable.
616  llvm::BasicBlock *unreachableBB = CGF.getUnreachableBlock();
617  for (llvm::BasicBlock::use_iterator
618  i = entry->use_begin(), e = entry->use_end(); i != e; ) {
619  llvm::Use &use = *i;
620  ++i;
621 
622  use.set(unreachableBB);
623 
624  // The only uses should be fixup switches.
625  llvm::SwitchInst *si = cast<llvm::SwitchInst>(use.getUser());
626  if (si->getNumCases() == 1 && si->getDefaultDest() == unreachableBB) {
627  // Replace the switch with a branch.
628  llvm::BranchInst::Create(si->case_begin()->getCaseSuccessor(), si);
629 
630  // The switch operand is a load from the cleanup-dest alloca.
631  llvm::LoadInst *condition = cast<llvm::LoadInst>(si->getCondition());
632 
633  // Destroy the switch.
634  si->eraseFromParent();
635 
636  // Destroy the load.
637  assert(condition->getOperand(0) == CGF.NormalCleanupDest.getPointer());
638  assert(condition->use_empty());
639  condition->eraseFromParent();
640  }
641  }
642 
643  assert(entry->use_empty());
644  delete entry;
645 }
646 
647 /// Pops a cleanup block. If the block includes a normal cleanup, the
648 /// current insertion point is threaded through the cleanup, as are
649 /// any branch fixups on the cleanup.
650 void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
651  assert(!EHStack.empty() && "cleanup stack is empty!");
652  assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
653  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
654  assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
655 
656  // Remember activation information.
657  bool IsActive = Scope.isActive();
658  Address NormalActiveFlag =
660  : Address::invalid();
661  Address EHActiveFlag =
662  Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag()
663  : Address::invalid();
664 
665  // Check whether we need an EH cleanup. This is only true if we've
666  // generated a lazy EH cleanup block.
667  llvm::BasicBlock *EHEntry = Scope.getCachedEHDispatchBlock();
668  assert(Scope.hasEHBranches() == (EHEntry != nullptr));
669  bool RequiresEHCleanup = (EHEntry != nullptr);
671 
672  // Check the three conditions which might require a normal cleanup:
673 
674  // - whether there are branch fix-ups through this cleanup
675  unsigned FixupDepth = Scope.getFixupDepth();
676  bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
677 
678  // - whether there are branch-throughs or branch-afters
679  bool HasExistingBranches = Scope.hasBranches();
680 
681  // - whether there's a fallthrough
682  llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
683  bool HasFallthrough = (FallthroughSource != nullptr && IsActive);
684 
685  // Branch-through fall-throughs leave the insertion point set to the
686  // end of the last cleanup, which points to the current scope. The
687  // rest of IR gen doesn't need to worry about this; it only happens
688  // during the execution of PopCleanupBlocks().
689  bool HasPrebranchedFallthrough =
690  (FallthroughSource && FallthroughSource->getTerminator());
691 
692  // If this is a normal cleanup, then having a prebranched
693  // fallthrough implies that the fallthrough source unconditionally
694  // jumps here.
695  assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
696  (Scope.getNormalBlock() &&
697  FallthroughSource->getTerminator()->getSuccessor(0)
698  == Scope.getNormalBlock()));
699 
700  bool RequiresNormalCleanup = false;
701  if (Scope.isNormalCleanup() &&
702  (HasFixups || HasExistingBranches || HasFallthrough)) {
703  RequiresNormalCleanup = true;
704  }
705 
706  // If we have a prebranched fallthrough into an inactive normal
707  // cleanup, rewrite it so that it leads to the appropriate place.
708  if (Scope.isNormalCleanup() && HasPrebranchedFallthrough && !IsActive) {
709  llvm::BasicBlock *prebranchDest;
710 
711  // If the prebranch is semantically branching through the next
712  // cleanup, just forward it to the next block, leaving the
713  // insertion point in the prebranched block.
714  if (FallthroughIsBranchThrough) {
715  EHScope &enclosing = *EHStack.find(Scope.getEnclosingNormalCleanup());
716  prebranchDest = CreateNormalEntry(*this, cast<EHCleanupScope>(enclosing));
717 
718  // Otherwise, we need to make a new block. If the normal cleanup
719  // isn't being used at all, we could actually reuse the normal
720  // entry block, but this is simpler, and it avoids conflicts with
721  // dead optimistic fixup branches.
722  } else {
723  prebranchDest = createBasicBlock("forwarded-prebranch");
724  EmitBlock(prebranchDest);
725  }
726 
727  llvm::BasicBlock *normalEntry = Scope.getNormalBlock();
728  assert(normalEntry && !normalEntry->use_empty());
729 
730  ForwardPrebranchedFallthrough(FallthroughSource,
731  normalEntry, prebranchDest);
732  }
733 
734  // If we don't need the cleanup at all, we're done.
735  if (!RequiresNormalCleanup && !RequiresEHCleanup) {
736  destroyOptimisticNormalEntry(*this, Scope);
737  EHStack.popCleanup(); // safe because there are no fixups
738  assert(EHStack.getNumBranchFixups() == 0 ||
739  EHStack.hasNormalCleanups());
740  return;
741  }
742 
743  // Copy the cleanup emission data out. This uses either a stack
744  // array or malloc'd memory, depending on the size, which is
745  // behavior that SmallVector would provide, if we could use it
746  // here. Unfortunately, if you ask for a SmallVector<char>, the
747  // alignment isn't sufficient.
748  auto *CleanupSource = reinterpret_cast<char *>(Scope.getCleanupBuffer());
749  llvm::AlignedCharArray<EHScopeStack::ScopeStackAlignment, 8 * sizeof(void *)> CleanupBufferStack;
750  std::unique_ptr<char[]> CleanupBufferHeap;
751  size_t CleanupSize = Scope.getCleanupSize();
753 
754  if (CleanupSize <= sizeof(CleanupBufferStack)) {
755  memcpy(CleanupBufferStack.buffer, CleanupSource, CleanupSize);
756  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferStack.buffer);
757  } else {
758  CleanupBufferHeap.reset(new char[CleanupSize]);
759  memcpy(CleanupBufferHeap.get(), CleanupSource, CleanupSize);
760  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferHeap.get());
761  }
762 
763  EHScopeStack::Cleanup::Flags cleanupFlags;
764  if (Scope.isNormalCleanup())
765  cleanupFlags.setIsNormalCleanupKind();
766  if (Scope.isEHCleanup())
767  cleanupFlags.setIsEHCleanupKind();
768 
769  if (!RequiresNormalCleanup) {
770  destroyOptimisticNormalEntry(*this, Scope);
771  EHStack.popCleanup();
772  } else {
773  // If we have a fallthrough and no other need for the cleanup,
774  // emit it directly.
775  if (HasFallthrough && !HasPrebranchedFallthrough &&
776  !HasFixups && !HasExistingBranches) {
777 
778  destroyOptimisticNormalEntry(*this, Scope);
779  EHStack.popCleanup();
780 
781  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
782 
783  // Otherwise, the best approach is to thread everything through
784  // the cleanup block and then try to clean up after ourselves.
785  } else {
786  // Force the entry block to exist.
787  llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
788 
789  // I. Set up the fallthrough edge in.
790 
791  CGBuilderTy::InsertPoint savedInactiveFallthroughIP;
792 
793  // If there's a fallthrough, we need to store the cleanup
794  // destination index. For fall-throughs this is always zero.
795  if (HasFallthrough) {
796  if (!HasPrebranchedFallthrough)
797  Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
798 
799  // Otherwise, save and clear the IP if we don't have fallthrough
800  // because the cleanup is inactive.
801  } else if (FallthroughSource) {
802  assert(!IsActive && "source without fallthrough for active cleanup");
803  savedInactiveFallthroughIP = Builder.saveAndClearIP();
804  }
805 
806  // II. Emit the entry block. This implicitly branches to it if
807  // we have fallthrough. All the fixups and existing branches
808  // should already be branched to it.
809  EmitBlock(NormalEntry);
810 
811  // III. Figure out where we're going and build the cleanup
812  // epilogue.
813 
814  bool HasEnclosingCleanups =
815  (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
816 
817  // Compute the branch-through dest if we need it:
818  // - if there are branch-throughs threaded through the scope
819  // - if fall-through is a branch-through
820  // - if there are fixups that will be optimistically forwarded
821  // to the enclosing cleanup
822  llvm::BasicBlock *BranchThroughDest = nullptr;
823  if (Scope.hasBranchThroughs() ||
824  (FallthroughSource && FallthroughIsBranchThrough) ||
825  (HasFixups && HasEnclosingCleanups)) {
826  assert(HasEnclosingCleanups);
827  EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
828  BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
829  }
830 
831  llvm::BasicBlock *FallthroughDest = nullptr;
833 
834  // If there's exactly one branch-after and no other threads,
835  // we can route it without a switch.
836  if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
837  Scope.getNumBranchAfters() == 1) {
838  assert(!BranchThroughDest || !IsActive);
839 
840  // Clean up the possibly dead store to the cleanup dest slot.
841  llvm::Instruction *NormalCleanupDestSlot =
842  cast<llvm::Instruction>(getNormalCleanupDestSlot().getPointer());
843  if (NormalCleanupDestSlot->hasOneUse()) {
844  NormalCleanupDestSlot->user_back()->eraseFromParent();
845  NormalCleanupDestSlot->eraseFromParent();
846  NormalCleanupDest = Address::invalid();
847  }
848 
849  llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
850  InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
851 
852  // Build a switch-out if we need it:
853  // - if there are branch-afters threaded through the scope
854  // - if fall-through is a branch-after
855  // - if there are fixups that have nowhere left to go and
856  // so must be immediately resolved
857  } else if (Scope.getNumBranchAfters() ||
858  (HasFallthrough && !FallthroughIsBranchThrough) ||
859  (HasFixups && !HasEnclosingCleanups)) {
860 
861  llvm::BasicBlock *Default =
862  (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
863 
864  // TODO: base this on the number of branch-afters and fixups
865  const unsigned SwitchCapacity = 10;
866 
867  llvm::LoadInst *Load =
868  createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
869  nullptr);
870  llvm::SwitchInst *Switch =
871  llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
872 
873  InstsToAppend.push_back(Load);
874  InstsToAppend.push_back(Switch);
875 
876  // Branch-after fallthrough.
877  if (FallthroughSource && !FallthroughIsBranchThrough) {
878  FallthroughDest = createBasicBlock("cleanup.cont");
879  if (HasFallthrough)
880  Switch->addCase(Builder.getInt32(0), FallthroughDest);
881  }
882 
883  for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
884  Switch->addCase(Scope.getBranchAfterIndex(I),
885  Scope.getBranchAfterBlock(I));
886  }
887 
888  // If there aren't any enclosing cleanups, we can resolve all
889  // the fixups now.
890  if (HasFixups && !HasEnclosingCleanups)
891  ResolveAllBranchFixups(*this, Switch, NormalEntry);
892  } else {
893  // We should always have a branch-through destination in this case.
894  assert(BranchThroughDest);
895  InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
896  }
897 
898  // IV. Pop the cleanup and emit it.
899  EHStack.popCleanup();
900  assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
901 
902  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
903 
904  // Append the prepared cleanup prologue from above.
905  llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
906  for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
907  NormalExit->getInstList().push_back(InstsToAppend[I]);
908 
909  // Optimistically hope that any fixups will continue falling through.
910  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
911  I < E; ++I) {
912  BranchFixup &Fixup = EHStack.getBranchFixup(I);
913  if (!Fixup.Destination) continue;
914  if (!Fixup.OptimisticBranchBlock) {
915  createStoreInstBefore(Builder.getInt32(Fixup.DestinationIndex),
916  getNormalCleanupDestSlot(),
917  Fixup.InitialBranch);
918  Fixup.InitialBranch->setSuccessor(0, NormalEntry);
919  }
920  Fixup.OptimisticBranchBlock = NormalExit;
921  }
922 
923  // V. Set up the fallthrough edge out.
924 
925  // Case 1: a fallthrough source exists but doesn't branch to the
926  // cleanup because the cleanup is inactive.
927  if (!HasFallthrough && FallthroughSource) {
928  // Prebranched fallthrough was forwarded earlier.
929  // Non-prebranched fallthrough doesn't need to be forwarded.
930  // Either way, all we need to do is restore the IP we cleared before.
931  assert(!IsActive);
932  Builder.restoreIP(savedInactiveFallthroughIP);
933 
934  // Case 2: a fallthrough source exists and should branch to the
935  // cleanup, but we're not supposed to branch through to the next
936  // cleanup.
937  } else if (HasFallthrough && FallthroughDest) {
938  assert(!FallthroughIsBranchThrough);
939  EmitBlock(FallthroughDest);
940 
941  // Case 3: a fallthrough source exists and should branch to the
942  // cleanup and then through to the next.
943  } else if (HasFallthrough) {
944  // Everything is already set up for this.
945 
946  // Case 4: no fallthrough source exists.
947  } else {
948  Builder.ClearInsertionPoint();
949  }
950 
951  // VI. Assorted cleaning.
952 
953  // Check whether we can merge NormalEntry into a single predecessor.
954  // This might invalidate (non-IR) pointers to NormalEntry.
955  llvm::BasicBlock *NewNormalEntry =
956  SimplifyCleanupEntry(*this, NormalEntry);
957 
958  // If it did invalidate those pointers, and NormalEntry was the same
959  // as NormalExit, go back and patch up the fixups.
960  if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
961  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
962  I < E; ++I)
963  EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
964  }
965  }
966 
967  assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
968 
969  // Emit the EH cleanup if required.
970  if (RequiresEHCleanup) {
971  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
972 
973  EmitBlock(EHEntry);
974 
975  llvm::BasicBlock *NextAction = getEHDispatchBlock(EHParent);
976 
977  // Push a terminate scope or cleanupendpad scope around the potentially
978  // throwing cleanups. For funclet EH personalities, the cleanupendpad models
979  // program termination when cleanups throw.
980  bool PushedTerminate = false;
981  SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
982  CurrentFuncletPad);
983  llvm::CleanupPadInst *CPI = nullptr;
984 
985  const EHPersonality &Personality = EHPersonality::get(*this);
986  if (Personality.usesFuncletPads()) {
987  llvm::Value *ParentPad = CurrentFuncletPad;
988  if (!ParentPad)
989  ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
990  CurrentFuncletPad = CPI = Builder.CreateCleanupPad(ParentPad);
991  }
992 
993  // Non-MSVC personalities need to terminate when an EH cleanup throws.
994  if (!Personality.isMSVCPersonality()) {
995  EHStack.pushTerminate();
996  PushedTerminate = true;
997  }
998 
999  // We only actually emit the cleanup code if the cleanup is either
1000  // active or was used before it was deactivated.
1001  if (EHActiveFlag.isValid() || IsActive) {
1002  cleanupFlags.setIsForEHCleanup();
1003  EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
1004  }
1005 
1006  if (CPI)
1007  Builder.CreateCleanupRet(CPI, NextAction);
1008  else
1009  Builder.CreateBr(NextAction);
1010 
1011  // Leave the terminate scope.
1012  if (PushedTerminate)
1013  EHStack.popTerminate();
1014 
1015  Builder.restoreIP(SavedIP);
1016 
1017  SimplifyCleanupEntry(*this, EHEntry);
1018  }
1019 }
1020 
1021 /// isObviouslyBranchWithoutCleanups - Return true if a branch to the
1022 /// specified destination obviously has no cleanups to run. 'false' is always
1023 /// a conservatively correct answer for this method.
1025  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1026  && "stale jump destination");
1027 
1028  // Calculate the innermost active normal cleanup.
1029  EHScopeStack::stable_iterator TopCleanup =
1030  EHStack.getInnermostActiveNormalCleanup();
1031 
1032  // If we're not in an active normal cleanup scope, or if the
1033  // destination scope is within the innermost active normal cleanup
1034  // scope, we don't need to worry about fixups.
1035  if (TopCleanup == EHStack.stable_end() ||
1036  TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid
1037  return true;
1038 
1039  // Otherwise, we might need some cleanups.
1040  return false;
1041 }
1042 
1043 
1044 /// Terminate the current block by emitting a branch which might leave
1045 /// the current cleanup-protected scope. The target scope may not yet
1046 /// be known, in which case this will require a fixup.
1047 ///
1048 /// As a side-effect, this method clears the insertion point.
1050  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1051  && "stale jump destination");
1052 
1053  if (!HaveInsertPoint())
1054  return;
1055 
1056  // Create the branch.
1057  llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
1058 
1059  // Calculate the innermost active normal cleanup.
1061  TopCleanup = EHStack.getInnermostActiveNormalCleanup();
1062 
1063  // If we're not in an active normal cleanup scope, or if the
1064  // destination scope is within the innermost active normal cleanup
1065  // scope, we don't need to worry about fixups.
1066  if (TopCleanup == EHStack.stable_end() ||
1067  TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
1068  Builder.ClearInsertionPoint();
1069  return;
1070  }
1071 
1072  // If we can't resolve the destination cleanup scope, just add this
1073  // to the current cleanup scope as a branch fixup.
1074  if (!Dest.getScopeDepth().isValid()) {
1075  BranchFixup &Fixup = EHStack.addBranchFixup();
1076  Fixup.Destination = Dest.getBlock();
1077  Fixup.DestinationIndex = Dest.getDestIndex();
1078  Fixup.InitialBranch = BI;
1079  Fixup.OptimisticBranchBlock = nullptr;
1080 
1081  Builder.ClearInsertionPoint();
1082  return;
1083  }
1084 
1085  // Otherwise, thread through all the normal cleanups in scope.
1086 
1087  // Store the index at the start.
1088  llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
1089  createStoreInstBefore(Index, getNormalCleanupDestSlot(), BI);
1090 
1091  // Adjust BI to point to the first cleanup block.
1092  {
1094  cast<EHCleanupScope>(*EHStack.find(TopCleanup));
1095  BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
1096  }
1097 
1098  // Add this destination to all the scopes involved.
1099  EHScopeStack::stable_iterator I = TopCleanup;
1101  if (E.strictlyEncloses(I)) {
1102  while (true) {
1103  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
1104  assert(Scope.isNormalCleanup());
1105  I = Scope.getEnclosingNormalCleanup();
1106 
1107  // If this is the last cleanup we're propagating through, tell it
1108  // that there's a resolved jump moving through it.
1109  if (!E.strictlyEncloses(I)) {
1110  Scope.addBranchAfter(Index, Dest.getBlock());
1111  break;
1112  }
1113 
1114  // Otherwise, tell the scope that there's a jump propagating
1115  // through it. If this isn't new information, all the rest of
1116  // the work has been done before.
1117  if (!Scope.addBranchThrough(Dest.getBlock()))
1118  break;
1119  }
1120  }
1121 
1122  Builder.ClearInsertionPoint();
1123 }
1124 
1127  // If we needed a normal block for any reason, that counts.
1128  if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
1129  return true;
1130 
1131  // Check whether any enclosed cleanups were needed.
1133  I = EHStack.getInnermostNormalCleanup();
1134  I != C; ) {
1135  assert(C.strictlyEncloses(I));
1136  EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
1137  if (S.getNormalBlock()) return true;
1138  I = S.getEnclosingNormalCleanup();
1139  }
1140 
1141  return false;
1142 }
1143 
1144 static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
1146  // If we needed an EH block for any reason, that counts.
1147  if (EHStack.find(cleanup)->hasEHBranches())
1148  return true;
1149 
1150  // Check whether any enclosed cleanups were needed.
1152  i = EHStack.getInnermostEHScope(); i != cleanup; ) {
1153  assert(cleanup.strictlyEncloses(i));
1154 
1155  EHScope &scope = *EHStack.find(i);
1156  if (scope.hasEHBranches())
1157  return true;
1158 
1159  i = scope.getEnclosingEHScope();
1160  }
1161 
1162  return false;
1163 }
1164 
1168 };
1169 
1170 /// The given cleanup block is changing activation state. Configure a
1171 /// cleanup variable if necessary.
1172 ///
1173 /// It would be good if we had some way of determining if there were
1174 /// extra uses *after* the change-over point.
1178  llvm::Instruction *dominatingIP) {
1179  EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
1180 
1181  // We always need the flag if we're activating the cleanup in a
1182  // conditional context, because we have to assume that the current
1183  // location doesn't necessarily dominate the cleanup's code.
1184  bool isActivatedInConditional =
1185  (kind == ForActivation && CGF.isInConditionalBranch());
1186 
1187  bool needFlag = false;
1188 
1189  // Calculate whether the cleanup was used:
1190 
1191  // - as a normal cleanup
1192  if (Scope.isNormalCleanup() &&
1193  (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
1195  needFlag = true;
1196  }
1197 
1198  // - as an EH cleanup
1199  if (Scope.isEHCleanup() &&
1200  (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
1201  Scope.setTestFlagInEHCleanup();
1202  needFlag = true;
1203  }
1204 
1205  // If it hasn't yet been used as either, we're done.
1206  if (!needFlag) return;
1207 
1208  Address var = Scope.getActiveFlag();
1209  if (!var.isValid()) {
1210  var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), CharUnits::One(),
1211  "cleanup.isactive");
1212  Scope.setActiveFlag(var);
1213 
1214  assert(dominatingIP && "no existing variable and no dominating IP!");
1215 
1216  // Initialize to true or false depending on whether it was
1217  // active up to this point.
1218  llvm::Constant *value = CGF.Builder.getInt1(kind == ForDeactivation);
1219 
1220  // If we're in a conditional block, ignore the dominating IP and
1221  // use the outermost conditional branch.
1222  if (CGF.isInConditionalBranch()) {
1223  CGF.setBeforeOutermostConditional(value, var);
1224  } else {
1225  createStoreInstBefore(value, var, dominatingIP);
1226  }
1227  }
1228 
1229  CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
1230 }
1231 
1232 /// Activate a cleanup that was created in an inactivated state.
1234  llvm::Instruction *dominatingIP) {
1235  assert(C != EHStack.stable_end() && "activating bottom of stack?");
1236  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1237  assert(!Scope.isActive() && "double activation");
1238 
1239  SetupCleanupBlockActivation(*this, C, ForActivation, dominatingIP);
1240 
1241  Scope.setActive(true);
1242 }
1243 
1244 /// Deactive a cleanup that was created in an active state.
1246  llvm::Instruction *dominatingIP) {
1247  assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
1248  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1249  assert(Scope.isActive() && "double deactivation");
1250 
1251  // If it's the top of the stack, just pop it, but do so only if it belongs
1252  // to the current RunCleanupsScope.
1253  if (C == EHStack.stable_begin() &&
1254  CurrentCleanupScopeDepth.strictlyEncloses(C)) {
1255  // If it's a normal cleanup, we need to pretend that the
1256  // fallthrough is unreachable.
1257  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1258  PopCleanupBlock();
1259  Builder.restoreIP(SavedIP);
1260  return;
1261  }
1262 
1263  // Otherwise, follow the general case.
1264  SetupCleanupBlockActivation(*this, C, ForDeactivation, dominatingIP);
1265 
1266  Scope.setActive(false);
1267 }
1268 
1270  if (!NormalCleanupDest.isValid())
1271  NormalCleanupDest =
1272  CreateDefaultAlignTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
1273  return NormalCleanupDest;
1274 }
1275 
1276 /// Emits all the code to cause the given temporary to be cleaned up.
1278  QualType TempType,
1279  Address Ptr) {
1280  pushDestroy(NormalAndEHCleanup, Ptr, TempType, destroyCXXObject,
1281  /*useEHCleanup*/ true);
1282 }
bool isAggregate() const
Definition: CGValue.h:53
const llvm::DataLayout & getDataLayout() const
void pushTerminate()
Push a terminate handler on the stack.
Definition: CGCleanup.cpp:258
static llvm::BasicBlock * CreateNormalEntry(CodeGenFunction &CGF, EHCleanupScope &Scope)
Definition: CGCleanup.cpp:511
EHScopeStack::stable_iterator getEnclosingEHScope() const
Definition: CGCleanup.h:137
void ActivateCleanupBlock(EHScopeStack::stable_iterator Cleanup, llvm::Instruction *DominatingIP)
ActivateCleanupBlock - Activates an initially-inactive cleanup.
Definition: CGCleanup.cpp:1233
A (possibly-)qualified type.
Definition: Type.h:634
bool usesFuncletPads() const
Does this personality use landingpads or the family of pad instructions designed to form funclets...
Definition: CGCleanup.h:633
static llvm::LoadInst * createLoadInstBefore(Address addr, const Twine &name, llvm::Instruction *beforeInst)
Definition: CGCleanup.cpp:316
static void destroyOptimisticNormalEntry(CodeGenFunction &CGF, EHCleanupScope &scope)
We don&#39;t need a normal entry block for the given cleanup.
Definition: CGCleanup.cpp:610
llvm::BasicBlock * getCachedEHDispatchBlock() const
Definition: CGCleanup.h:123
bool HaveInsertPoint() const
HaveInsertPoint - True if an insertion point is defined.
void initFullExprCleanupWithFlag(Address ActiveFlag)
Definition: CGCleanup.cpp:298
static stable_iterator stable_end()
Create a stable reference to the bottom of the EH stack.
Definition: EHScopeStack.h:383
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:2227
bool hasEHBranches() const
Definition: CGCleanup.h:131
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:364
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:590
stable_iterator stable_begin() const
Create a stable reference to the top of the EH stack.
Definition: EHScopeStack.h:378
llvm::BasicBlock * getNormalBlock() const
Definition: CGCleanup.h:312
unsigned getNumFilters() const
Definition: CGCleanup.h:460
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:344
static void EmitCleanup(CodeGenFunction &CGF, EHScopeStack::Cleanup *Fn, EHScopeStack::Cleanup::Flags flags, Address ActiveFlag)
Definition: CGCleanup.cpp:561
llvm::Value * getPointer() const
Definition: Address.h:37
iterator begin() const
Returns an iterator pointing to the innermost EH scope.
Definition: CGCleanup.h:566
A protected scope for zero-cost EH handling.
Definition: CGCleanup.h:43
A scope which attempts to handle some, possibly all, types of exceptions.
Definition: CGCleanup.h:147
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:409
bool isObviouslyBranchWithoutCleanups(JumpDest Dest) const
isObviouslyBranchWithoutCleanups - Return true if a branch to the specified destination obviously has...
Definition: CGCleanup.cpp:1024
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:279
An exceptions scope which calls std::terminate if any exception reaches it.
Definition: CGCleanup.h:479
bool isMSVCPersonality() const
Definition: CGCleanup.h:637
CodeGenFunction - This class organizes the per-function state that is used while generating LLVM code...
ForActivation_t
Definition: CGCleanup.cpp:1165
bool shouldTestFlagInNormalCleanup() const
Definition: CGCleanup.h:335
Denotes a cleanup that should run when a scope is exited using exceptional control flow (a throw stat...
Definition: EHScopeStack.h:80
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:65
unsigned getNumBranchFixups() const
Definition: EHScopeStack.h:401
class EHCatchScope * pushCatch(unsigned NumHandlers)
Push a set of catch handlers on the stack.
Definition: CGCleanup.cpp:250
BranchFixup & getBranchFixup(unsigned I)
Definition: EHScopeStack.h:402
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:37
void setNormalBlock(llvm::BasicBlock *BB)
Definition: CGCleanup.h:313
CharUnits getAlignment() const
Return the alignment of this pointer.
Definition: Address.h:66
bool isComplex() const
Definition: CGValue.h:52
bool hasNormalCleanups() const
Determines whether there are any normal cleanups on the stack.
Definition: EHScopeStack.h:349
bool containsOnlyLifetimeMarkers(stable_iterator Old) const
Definition: CGCleanup.cpp:147
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:99
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:84
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:129
void popFilter()
Pops an exceptions filter off the stack.
Definition: CGCleanup.cpp:241
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:105
Address NormalCleanupDest
i32s containing the indexes of the cleanup destinations.
static bool IsUsedAsEHCleanup(EHScopeStack &EHStack, EHScopeStack::stable_iterator cleanup)
Definition: CGCleanup.cpp:1144
static size_t getSizeForNumHandlers(unsigned N)
Definition: CGCleanup.h:177
Address getAggregateAddress() const
getAggregateAddr() - Return the Value* of the address of the aggregate.
Definition: CGValue.h:70
bool isValid() const
Definition: Address.h:35
static CharUnits One()
One - Construct a CharUnits quantity of one.
Definition: CharUnits.h:57
unsigned getFixupDepth() const
Definition: CGCleanup.h:346
std::pair< llvm::Value *, llvm::Value * > ComplexPairTy
static void createStoreInstBefore(llvm::Value *value, Address addr, llvm::Instruction *beforeInst)
Definition: CGCleanup.cpp:310
unsigned getNumBranchAfters() const
Return the number of unique branch-afters on this scope.
Definition: CGCleanup.h:380
RValue - This trivial value class is used to represent the result of an expression that is evaluated...
Definition: CGValue.h:38
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:326
llvm::BranchInst * InitialBranch
The initial branch of the fixup.
Definition: EHScopeStack.h:52
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:178
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:118
EHScopeStack::stable_iterator getScopeDepth() const
void clearFixups()
Clears the branch-fixups list.
Definition: EHScopeStack.h:414
static Address invalid()
Definition: Address.h:34
stable_iterator getInnermostNormalCleanup() const
Returns the innermost normal cleanup on the stack, or stable_end() if there are no normal cleanups...
Definition: EHScopeStack.h:355
std::pair< llvm::Value *, llvm::Value * > getComplexVal() const
getComplexVal - Return the real/imag components of this complex value.
Definition: CGValue.h:65
size_t getCleanupSize() const
Definition: CGCleanup.h:351
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:62
llvm::ConstantInt * getBranchAfterIndex(unsigned I) const
Definition: CGCleanup.h:389
void ResolveBranchFixups(llvm::BasicBlock *Target)
Definition: CGCleanup.cpp:384
void setActiveFlag(Address Var)
Definition: CGCleanup.h:327
stable_iterator stabilize(iterator it) const
Translates an iterator into a stable_iterator.
Definition: CGCleanup.h:597
bool encloses(stable_iterator I) const
Returns true if this scope encloses I.
Definition: EHScopeStack.h:123
size_t getAllocatedSize() const
Definition: CGCleanup.h:283
llvm::BasicBlock * OptimisticBranchBlock
The block containing the terminator which needs to be modified into a switch if this fixup is resolve...
Definition: EHScopeStack.h:40
void popCleanup()
Pops a cleanup scope off the stack. This is private to CGCleanup.cpp.
Definition: CGCleanup.cpp:208
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:423
llvm::BasicBlock * Destination
The ultimate destination of the branch.
Definition: EHScopeStack.h:46
Kind
A saved depth on the scope stack.
Definition: EHScopeStack.h:106
Represents a C++ temporary.
Definition: ExprCXX.h:1184
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:1245
EHScopeStack::stable_iterator getEnclosingNormalCleanup() const
Definition: CGCleanup.h:347
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:1277
An aligned address.
Definition: Address.h:24
unsigned DestinationIndex
The destination index value.
Definition: EHScopeStack.h:49
__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:456
static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack, EHScopeStack::stable_iterator C)
Definition: CGCleanup.cpp:1125
static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit, llvm::BasicBlock *From, llvm::BasicBlock *To)
Definition: CGCleanup.cpp:586
llvm::Value * getScalarVal() const
getScalarVal() - Return the Value* of this scalar value.
Definition: CGValue.h:58
class EHFilterScope * pushFilter(unsigned NumFilters)
Push an exceptions filter on the stack.
Definition: CGCleanup.cpp:233
Dataflow Directional Tag Classes.
static RValue getComplex(llvm::Value *V1, llvm::Value *V2)
Definition: CGValue.h:92
void popNullFixups()
Pops lazily-removed fixups from the end of the list.
Definition: CGCleanup.cpp:269
bool shouldTestFlagInEHCleanup() const
Definition: CGCleanup.h:342
void addBranchAfter(llvm::ConstantInt *Index, llvm::BasicBlock *Block)
Add a branch-after to this cleanup scope.
Definition: CGCleanup.h:372
Address CreateStructGEP(Address Addr, unsigned Index, CharUnits Offset, const llvm::Twine &Name="")
Definition: CGBuilder.h:171
static llvm::BasicBlock * SimplifyCleanupEntry(CodeGenFunction &CGF, llvm::BasicBlock *Entry)
Attempts to reduce a cleanup&#39;s entry block to a fallthrough.
Definition: CGCleanup.cpp:527
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:69
Header for data within LifetimeExtendedCleanupStack.
llvm::StoreInst * CreateStore(llvm::Value *Val, Address Addr, bool IsVolatile=false)
Definition: CGBuilder.h:107
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:1175
stable_iterator getInnermostActiveNormalCleanup() const
Definition: CGCleanup.cpp:173
llvm::Value * getAggregatePointer() const
Definition: CGValue.h:75
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
EmitBlock - Emit the given block.
Definition: CGStmt.cpp:442
bool hasBranches() const
True if this cleanup scope has any branch-afters or branch-throughs.
Definition: CGCleanup.h:359
Address getActiveFlag() const
Definition: CGCleanup.h:324
The exceptions personality for a function.
Definition: CGCleanup.h:603
unsigned kind
All of the diagnostics that can be emitted by the frontend.
Definition: DiagnosticIDs.h:60
llvm::BasicBlock * getBranchAfterBlock(unsigned I) const
Definition: CGCleanup.h:384
A cleanup scope which generates the cleanup blocks lazily.
Definition: CGCleanup.h:232
stable_iterator getInnermostEHScope() const
Definition: EHScopeStack.h:360
bool hasBranchThroughs() const
Determines if this cleanup scope has any branch throughs.
Definition: CGCleanup.h:414
An exceptions scope which filters exceptions thrown through it.
Definition: CGCleanup.h:437
static RValue get(llvm::Value *V)
Definition: CGValue.h:85
void EmitBranchThroughCleanup(JumpDest Dest)
EmitBranchThroughCleanup - Emit a branch from the current insert block through the normal cleanup han...
Definition: CGCleanup.cpp:1049
static RValue getAggregate(Address addr, bool isVolatile=false)
Definition: CGValue.h:106
Information for lazily generating a cleanup.
Definition: EHScopeStack.h:146
A non-stable pointer into the scope stack.
Definition: CGCleanup.h:502
void PopCleanupBlock(bool FallThroughIsBranchThrough=false)
PopCleanupBlock - Will pop the cleanup entry on the stack and process all branch fixups.
Definition: CGCleanup.cpp:650
bool isScalar() const
Definition: CGValue.h:51
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.