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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, CGF.Builder.CreateStructGEP(addr, 0));
56  CGF.Builder.CreateStore(V.second, CGF.Builder.CreateStructGEP(addr, 1));
57  return saved_type(addr.getPointer(), ComplexAddress);
58  }
59 
60  assert(rv.isAggregate());
61  Address V = rv.getAggregateAddress(); // TODO: volatile?
62  if (!DominatingLLVMValue::needsSaving(V.getPointer()))
63  return saved_type(V.getPointer(), AggregateLiteral,
64  V.getAlignment().getQuantity());
65 
66  Address addr =
67  CGF.CreateTempAlloca(V.getType(), CGF.getPointerAlign(), "saved-rvalue");
68  CGF.Builder.CreateStore(V.getPointer(), addr);
69  return saved_type(addr.getPointer(), AggregateAddress,
70  V.getAlignment().getQuantity());
71 }
72 
73 /// Given a saved r-value produced by SaveRValue, perform the code
74 /// necessary to restore it to usability at the current insertion
75 /// point.
77  auto getSavingAddress = [&](llvm::Value *value) {
78  auto alignment = cast<llvm::AllocaInst>(value)->getAlignment();
79  return Address(value, CharUnits::fromQuantity(alignment));
80  };
81  switch (K) {
82  case ScalarLiteral:
83  return RValue::get(Value);
84  case ScalarAddress:
85  return RValue::get(CGF.Builder.CreateLoad(getSavingAddress(Value)));
86  case AggregateLiteral:
88  case AggregateAddress: {
89  auto addr = CGF.Builder.CreateLoad(getSavingAddress(Value));
91  }
92  case ComplexAddress: {
93  Address address = getSavingAddress(Value);
94  llvm::Value *real =
95  CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(address, 0));
96  llvm::Value *imag =
97  CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(address, 1));
98  return RValue::getComplex(real, imag);
99  }
100  }
101 
102  llvm_unreachable("bad saved r-value kind");
103 }
104 
105 /// Push an entry of the given size onto this protected-scope stack.
106 char *EHScopeStack::allocate(size_t Size) {
107  Size = llvm::alignTo(Size, ScopeStackAlignment);
108  if (!StartOfBuffer) {
109  unsigned Capacity = 1024;
110  while (Capacity < Size) Capacity *= 2;
111  StartOfBuffer = new char[Capacity];
112  StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
113  } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
114  unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
115  unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
116 
117  unsigned NewCapacity = CurrentCapacity;
118  do {
119  NewCapacity *= 2;
120  } while (NewCapacity < UsedCapacity + Size);
121 
122  char *NewStartOfBuffer = new char[NewCapacity];
123  char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
124  char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
125  memcpy(NewStartOfData, StartOfData, UsedCapacity);
126  delete [] StartOfBuffer;
127  StartOfBuffer = NewStartOfBuffer;
128  EndOfBuffer = NewEndOfBuffer;
129  StartOfData = NewStartOfData;
130  }
131 
132  assert(StartOfBuffer + Size <= StartOfData);
133  StartOfData -= Size;
134  return StartOfData;
135 }
136 
137 void EHScopeStack::deallocate(size_t Size) {
138  StartOfData += llvm::alignTo(Size, ScopeStackAlignment);
139 }
140 
142  EHScopeStack::stable_iterator Old) const {
143  for (EHScopeStack::iterator it = begin(); stabilize(it) != Old; it++) {
144  EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*it);
145  if (!cleanup || !cleanup->isLifetimeMarker())
146  return false;
147  }
148 
149  return true;
150 }
151 
153  for (stable_iterator si = getInnermostEHScope(); si != stable_end(); ) {
154  // Skip lifetime markers.
155  if (auto *cleanup = dyn_cast<EHCleanupScope>(&*find(si)))
156  if (cleanup->isLifetimeMarker()) {
157  si = cleanup->getEnclosingEHScope();
158  continue;
159  }
160  return true;
161  }
162 
163  return false;
164 }
165 
169  si != se; ) {
170  EHCleanupScope &cleanup = cast<EHCleanupScope>(*find(si));
171  if (cleanup.isActive()) return si;
172  si = cleanup.getEnclosingNormalCleanup();
173  }
174  return stable_end();
175 }
176 
177 
178 void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
179  char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
180  bool IsNormalCleanup = Kind & NormalCleanup;
181  bool IsEHCleanup = Kind & EHCleanup;
182  bool IsActive = !(Kind & InactiveCleanup);
183  bool IsLifetimeMarker = Kind & LifetimeMarker;
185  new (Buffer) EHCleanupScope(IsNormalCleanup,
186  IsEHCleanup,
187  IsActive,
188  Size,
189  BranchFixups.size(),
190  InnermostNormalCleanup,
191  InnermostEHScope);
192  if (IsNormalCleanup)
193  InnermostNormalCleanup = stable_begin();
194  if (IsEHCleanup)
195  InnermostEHScope = stable_begin();
196  if (IsLifetimeMarker)
197  Scope->setLifetimeMarker();
198 
199  return Scope->getCleanupBuffer();
200 }
201 
203  assert(!empty() && "popping exception stack when not empty");
204 
205  assert(isa<EHCleanupScope>(*begin()));
206  EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
207  InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
208  InnermostEHScope = Cleanup.getEnclosingEHScope();
209  deallocate(Cleanup.getAllocatedSize());
210 
211  // Destroy the cleanup.
212  Cleanup.Destroy();
213 
214  // Check whether we can shrink the branch-fixups stack.
215  if (!BranchFixups.empty()) {
216  // If we no longer have any normal cleanups, all the fixups are
217  // complete.
218  if (!hasNormalCleanups())
219  BranchFixups.clear();
220 
221  // Otherwise we can still trim out unnecessary nulls.
222  else
223  popNullFixups();
224  }
225 }
226 
228  assert(getInnermostEHScope() == stable_end());
229  char *buffer = allocate(EHFilterScope::getSizeForNumFilters(numFilters));
230  EHFilterScope *filter = new (buffer) EHFilterScope(numFilters);
231  InnermostEHScope = stable_begin();
232  return filter;
233 }
234 
236  assert(!empty() && "popping exception stack when not empty");
237 
238  EHFilterScope &filter = cast<EHFilterScope>(*begin());
240 
241  InnermostEHScope = filter.getEnclosingEHScope();
242 }
243 
244 EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) {
245  char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers));
246  EHCatchScope *scope =
247  new (buffer) EHCatchScope(numHandlers, InnermostEHScope);
248  InnermostEHScope = stable_begin();
249  return scope;
250 }
251 
253  char *Buffer = allocate(EHTerminateScope::getSize());
254  new (Buffer) EHTerminateScope(InnermostEHScope);
255  InnermostEHScope = stable_begin();
256 }
257 
258 /// Remove any 'null' fixups on the stack. However, we can't pop more
259 /// fixups than the fixup depth on the innermost normal cleanup, or
260 /// else fixups that we try to add to that cleanup will end up in the
261 /// wrong place. We *could* try to shrink fixup depths, but that's
262 /// actually a lot of work for little benefit.
264  // We expect this to only be called when there's still an innermost
265  // normal cleanup; otherwise there really shouldn't be any fixups.
266  assert(hasNormalCleanups());
267 
268  EHScopeStack::iterator it = find(InnermostNormalCleanup);
269  unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
270  assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
271 
272  while (BranchFixups.size() > MinSize &&
273  BranchFixups.back().Destination == nullptr)
274  BranchFixups.pop_back();
275 }
276 
278  // Create a variable to decide whether the cleanup needs to be run.
279  Address active = CreateTempAllocaWithoutCast(
280  Builder.getInt1Ty(), CharUnits::One(), "cleanup.cond");
281 
282  // Initialize it to false at a site that's guaranteed to be run
283  // before each evaluation.
284  setBeforeOutermostConditional(Builder.getFalse(), active);
285 
286  // Initialize it to true at the current location.
287  Builder.CreateStore(Builder.getTrue(), active);
288 
289  return active;
290 }
291 
293  // Set that as the active flag in the cleanup.
294  EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
295  assert(!cleanup.hasActiveFlag() && "cleanup already has active flag?");
296  cleanup.setActiveFlag(ActiveFlag);
297 
298  if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
299  if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
300 }
301 
302 void EHScopeStack::Cleanup::anchor() {}
303 
304 static void createStoreInstBefore(llvm::Value *value, Address addr,
305  llvm::Instruction *beforeInst) {
306  auto store = new llvm::StoreInst(value, addr.getPointer(), beforeInst);
307  store->setAlignment(addr.getAlignment().getQuantity());
308 }
309 
310 static llvm::LoadInst *createLoadInstBefore(Address addr, const Twine &name,
311  llvm::Instruction *beforeInst) {
312  auto load = new llvm::LoadInst(addr.getPointer(), name, beforeInst);
313  load->setAlignment(addr.getAlignment().getQuantity());
314  return load;
315 }
316 
317 /// All the branch fixups on the EH stack have propagated out past the
318 /// outermost normal cleanup; resolve them all by adding cases to the
319 /// given switch instruction.
321  llvm::SwitchInst *Switch,
322  llvm::BasicBlock *CleanupEntry) {
323  llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
324 
325  for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
326  // Skip this fixup if its destination isn't set.
327  BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
328  if (Fixup.Destination == nullptr) continue;
329 
330  // If there isn't an OptimisticBranchBlock, then InitialBranch is
331  // still pointing directly to its destination; forward it to the
332  // appropriate cleanup entry. This is required in the specific
333  // case of
334  // { std::string s; goto lbl; }
335  // lbl:
336  // i.e. where there's an unresolved fixup inside a single cleanup
337  // entry which we're currently popping.
338  if (Fixup.OptimisticBranchBlock == nullptr) {
339  createStoreInstBefore(CGF.Builder.getInt32(Fixup.DestinationIndex),
341  Fixup.InitialBranch);
342  Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
343  }
344 
345  // Don't add this case to the switch statement twice.
346  if (!CasesAdded.insert(Fixup.Destination).second)
347  continue;
348 
349  Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
350  Fixup.Destination);
351  }
352 
353  CGF.EHStack.clearFixups();
354 }
355 
356 /// Transitions the terminator of the given exit-block of a cleanup to
357 /// be a cleanup switch.
358 static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
359  llvm::BasicBlock *Block) {
360  // If it's a branch, turn it into a switch whose default
361  // destination is its original target.
362  llvm::Instruction *Term = Block->getTerminator();
363  assert(Term && "can't transition block without terminator");
364 
365  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
366  assert(Br->isUnconditional());
368  "cleanup.dest", Term);
369  llvm::SwitchInst *Switch =
370  llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
371  Br->eraseFromParent();
372  return Switch;
373  } else {
374  return cast<llvm::SwitchInst>(Term);
375  }
376 }
377 
378 void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
379  assert(Block && "resolving a null target block");
380  if (!EHStack.getNumBranchFixups()) return;
381 
382  assert(EHStack.hasNormalCleanups() &&
383  "branch fixups exist with no normal cleanups on stack");
384 
385  llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
386  bool ResolvedAny = false;
387 
388  for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
389  // Skip this fixup if its destination doesn't match.
390  BranchFixup &Fixup = EHStack.getBranchFixup(I);
391  if (Fixup.Destination != Block) continue;
392 
393  Fixup.Destination = nullptr;
394  ResolvedAny = true;
395 
396  // If it doesn't have an optimistic branch block, LatestBranch is
397  // already pointing to the right place.
398  llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
399  if (!BranchBB)
400  continue;
401 
402  // Don't process the same optimistic branch block twice.
403  if (!ModifiedOptimisticBlocks.insert(BranchBB).second)
404  continue;
405 
406  llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
407 
408  // Add a case to the switch.
409  Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
410  }
411 
412  if (ResolvedAny)
413  EHStack.popNullFixups();
414 }
415 
416 /// Pops cleanup blocks until the given savepoint is reached.
419  std::initializer_list<llvm::Value **> ValuesToReload) {
420  assert(Old.isValid());
421 
422  bool HadBranches = false;
423  while (EHStack.stable_begin() != Old) {
424  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
425  HadBranches |= Scope.hasBranches();
426 
427  // As long as Old strictly encloses the scope's enclosing normal
428  // cleanup, we're going to emit another normal cleanup which
429  // fallthrough can propagate through.
430  bool FallThroughIsBranchThrough =
432 
433  PopCleanupBlock(FallThroughIsBranchThrough);
434  }
435 
436  // If we didn't have any branches, the insertion point before cleanups must
437  // dominate the current insertion point and we don't need to reload any
438  // values.
439  if (!HadBranches)
440  return;
441 
442  // Spill and reload all values that the caller wants to be live at the current
443  // insertion point.
444  for (llvm::Value **ReloadedValue : ValuesToReload) {
445  auto *Inst = dyn_cast_or_null<llvm::Instruction>(*ReloadedValue);
446  if (!Inst)
447  continue;
448 
449  // Don't spill static allocas, they dominate all cleanups. These are created
450  // by binding a reference to a local variable or temporary.
451  auto *AI = dyn_cast<llvm::AllocaInst>(Inst);
452  if (AI && AI->isStaticAlloca())
453  continue;
454 
455  Address Tmp =
456  CreateDefaultAlignTempAlloca(Inst->getType(), "tmp.exprcleanup");
457 
458  // Find an insertion point after Inst and spill it to the temporary.
459  llvm::BasicBlock::iterator InsertBefore;
460  if (auto *Invoke = dyn_cast<llvm::InvokeInst>(Inst))
461  InsertBefore = Invoke->getNormalDest()->getFirstInsertionPt();
462  else
463  InsertBefore = std::next(Inst->getIterator());
464  CGBuilderTy(CGM, &*InsertBefore).CreateStore(Inst, Tmp);
465 
466  // Reload the value at the current insertion point.
467  *ReloadedValue = Builder.CreateLoad(Tmp);
468  }
469 }
470 
471 /// Pops cleanup blocks until the given savepoint is reached, then add the
472 /// cleanups from the given savepoint in the lifetime-extended cleanups stack.
474  EHScopeStack::stable_iterator Old, size_t OldLifetimeExtendedSize,
475  std::initializer_list<llvm::Value **> ValuesToReload) {
476  PopCleanupBlocks(Old, ValuesToReload);
477 
478  // Move our deferred cleanups onto the EH stack.
479  for (size_t I = OldLifetimeExtendedSize,
480  E = LifetimeExtendedCleanupStack.size(); I != E; /**/) {
481  // Alignment should be guaranteed by the vptrs in the individual cleanups.
482  assert((I % alignof(LifetimeExtendedCleanupHeader) == 0) &&
483  "misaligned cleanup stack entry");
484 
486  reinterpret_cast<LifetimeExtendedCleanupHeader&>(
487  LifetimeExtendedCleanupStack[I]);
488  I += sizeof(Header);
489 
490  EHStack.pushCopyOfCleanup(Header.getKind(),
491  &LifetimeExtendedCleanupStack[I],
492  Header.getSize());
493  I += Header.getSize();
494 
495  if (Header.isConditional()) {
496  Address ActiveFlag =
497  reinterpret_cast<Address &>(LifetimeExtendedCleanupStack[I]);
498  initFullExprCleanupWithFlag(ActiveFlag);
499  I += sizeof(ActiveFlag);
500  }
501  }
502  LifetimeExtendedCleanupStack.resize(OldLifetimeExtendedSize);
503 }
504 
505 static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
507  assert(Scope.isNormalCleanup());
508  llvm::BasicBlock *Entry = Scope.getNormalBlock();
509  if (!Entry) {
510  Entry = CGF.createBasicBlock("cleanup");
511  Scope.setNormalBlock(Entry);
512  }
513  return Entry;
514 }
515 
516 /// Attempts to reduce a cleanup's entry block to a fallthrough. This
517 /// is basically llvm::MergeBlockIntoPredecessor, except
518 /// simplified/optimized for the tighter constraints on cleanup blocks.
519 ///
520 /// Returns the new block, whatever it is.
521 static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
522  llvm::BasicBlock *Entry) {
523  llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
524  if (!Pred) return Entry;
525 
526  llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
527  if (!Br || Br->isConditional()) return Entry;
528  assert(Br->getSuccessor(0) == Entry);
529 
530  // If we were previously inserting at the end of the cleanup entry
531  // block, we'll need to continue inserting at the end of the
532  // predecessor.
533  bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
534  assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
535 
536  // Kill the branch.
537  Br->eraseFromParent();
538 
539  // Replace all uses of the entry with the predecessor, in case there
540  // are phis in the cleanup.
541  Entry->replaceAllUsesWith(Pred);
542 
543  // Merge the blocks.
544  Pred->getInstList().splice(Pred->end(), Entry->getInstList());
545 
546  // Kill the entry block.
547  Entry->eraseFromParent();
548 
549  if (WasInsertBlock)
550  CGF.Builder.SetInsertPoint(Pred);
551 
552  return Pred;
553 }
554 
555 static void EmitCleanup(CodeGenFunction &CGF,
558  Address ActiveFlag) {
559  // If there's an active flag, load it and skip the cleanup if it's
560  // false.
561  llvm::BasicBlock *ContBB = nullptr;
562  if (ActiveFlag.isValid()) {
563  ContBB = CGF.createBasicBlock("cleanup.done");
564  llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
565  llvm::Value *IsActive
566  = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
567  CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
568  CGF.EmitBlock(CleanupBB);
569  }
570 
571  // Ask the cleanup to emit itself.
572  Fn->Emit(CGF, flags);
573  assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
574 
575  // Emit the continuation block if there was an active flag.
576  if (ActiveFlag.isValid())
577  CGF.EmitBlock(ContBB);
578 }
579 
580 static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
581  llvm::BasicBlock *From,
582  llvm::BasicBlock *To) {
583  // Exit is the exit block of a cleanup, so it always terminates in
584  // an unconditional branch or a switch.
585  llvm::Instruction *Term = Exit->getTerminator();
586 
587  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
588  assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
589  Br->setSuccessor(0, To);
590  } else {
591  llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
592  for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
593  if (Switch->getSuccessor(I) == From)
594  Switch->setSuccessor(I, To);
595  }
596 }
597 
598 /// We don't need a normal entry block for the given cleanup.
599 /// Optimistic fixup branches can cause these blocks to come into
600 /// existence anyway; if so, destroy it.
601 ///
602 /// The validity of this transformation is very much specific to the
603 /// exact ways in which we form branches to cleanup entries.
605  EHCleanupScope &scope) {
606  llvm::BasicBlock *entry = scope.getNormalBlock();
607  if (!entry) return;
608 
609  // Replace all the uses with unreachable.
610  llvm::BasicBlock *unreachableBB = CGF.getUnreachableBlock();
611  for (llvm::BasicBlock::use_iterator
612  i = entry->use_begin(), e = entry->use_end(); i != e; ) {
613  llvm::Use &use = *i;
614  ++i;
615 
616  use.set(unreachableBB);
617 
618  // The only uses should be fixup switches.
619  llvm::SwitchInst *si = cast<llvm::SwitchInst>(use.getUser());
620  if (si->getNumCases() == 1 && si->getDefaultDest() == unreachableBB) {
621  // Replace the switch with a branch.
622  llvm::BranchInst::Create(si->case_begin()->getCaseSuccessor(), si);
623 
624  // The switch operand is a load from the cleanup-dest alloca.
625  llvm::LoadInst *condition = cast<llvm::LoadInst>(si->getCondition());
626 
627  // Destroy the switch.
628  si->eraseFromParent();
629 
630  // Destroy the load.
631  assert(condition->getOperand(0) == CGF.NormalCleanupDest.getPointer());
632  assert(condition->use_empty());
633  condition->eraseFromParent();
634  }
635  }
636 
637  assert(entry->use_empty());
638  delete entry;
639 }
640 
641 /// Pops a cleanup block. If the block includes a normal cleanup, the
642 /// current insertion point is threaded through the cleanup, as are
643 /// any branch fixups on the cleanup.
644 void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
645  assert(!EHStack.empty() && "cleanup stack is empty!");
646  assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
647  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
648  assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
649 
650  // Remember activation information.
651  bool IsActive = Scope.isActive();
652  Address NormalActiveFlag =
654  : Address::invalid();
655  Address EHActiveFlag =
656  Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag()
657  : Address::invalid();
658 
659  // Check whether we need an EH cleanup. This is only true if we've
660  // generated a lazy EH cleanup block.
661  llvm::BasicBlock *EHEntry = Scope.getCachedEHDispatchBlock();
662  assert(Scope.hasEHBranches() == (EHEntry != nullptr));
663  bool RequiresEHCleanup = (EHEntry != nullptr);
665 
666  // Check the three conditions which might require a normal cleanup:
667 
668  // - whether there are branch fix-ups through this cleanup
669  unsigned FixupDepth = Scope.getFixupDepth();
670  bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
671 
672  // - whether there are branch-throughs or branch-afters
673  bool HasExistingBranches = Scope.hasBranches();
674 
675  // - whether there's a fallthrough
676  llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
677  bool HasFallthrough = (FallthroughSource != nullptr && IsActive);
678 
679  // Branch-through fall-throughs leave the insertion point set to the
680  // end of the last cleanup, which points to the current scope. The
681  // rest of IR gen doesn't need to worry about this; it only happens
682  // during the execution of PopCleanupBlocks().
683  bool HasPrebranchedFallthrough =
684  (FallthroughSource && FallthroughSource->getTerminator());
685 
686  // If this is a normal cleanup, then having a prebranched
687  // fallthrough implies that the fallthrough source unconditionally
688  // jumps here.
689  assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
690  (Scope.getNormalBlock() &&
691  FallthroughSource->getTerminator()->getSuccessor(0)
692  == Scope.getNormalBlock()));
693 
694  bool RequiresNormalCleanup = false;
695  if (Scope.isNormalCleanup() &&
696  (HasFixups || HasExistingBranches || HasFallthrough)) {
697  RequiresNormalCleanup = true;
698  }
699 
700  // If we have a prebranched fallthrough into an inactive normal
701  // cleanup, rewrite it so that it leads to the appropriate place.
702  if (Scope.isNormalCleanup() && HasPrebranchedFallthrough && !IsActive) {
703  llvm::BasicBlock *prebranchDest;
704 
705  // If the prebranch is semantically branching through the next
706  // cleanup, just forward it to the next block, leaving the
707  // insertion point in the prebranched block.
708  if (FallthroughIsBranchThrough) {
709  EHScope &enclosing = *EHStack.find(Scope.getEnclosingNormalCleanup());
710  prebranchDest = CreateNormalEntry(*this, cast<EHCleanupScope>(enclosing));
711 
712  // Otherwise, we need to make a new block. If the normal cleanup
713  // isn't being used at all, we could actually reuse the normal
714  // entry block, but this is simpler, and it avoids conflicts with
715  // dead optimistic fixup branches.
716  } else {
717  prebranchDest = createBasicBlock("forwarded-prebranch");
718  EmitBlock(prebranchDest);
719  }
720 
721  llvm::BasicBlock *normalEntry = Scope.getNormalBlock();
722  assert(normalEntry && !normalEntry->use_empty());
723 
724  ForwardPrebranchedFallthrough(FallthroughSource,
725  normalEntry, prebranchDest);
726  }
727 
728  // If we don't need the cleanup at all, we're done.
729  if (!RequiresNormalCleanup && !RequiresEHCleanup) {
730  destroyOptimisticNormalEntry(*this, Scope);
731  EHStack.popCleanup(); // safe because there are no fixups
732  assert(EHStack.getNumBranchFixups() == 0 ||
733  EHStack.hasNormalCleanups());
734  return;
735  }
736 
737  // Copy the cleanup emission data out. This uses either a stack
738  // array or malloc'd memory, depending on the size, which is
739  // behavior that SmallVector would provide, if we could use it
740  // here. Unfortunately, if you ask for a SmallVector<char>, the
741  // alignment isn't sufficient.
742  auto *CleanupSource = reinterpret_cast<char *>(Scope.getCleanupBuffer());
743  llvm::AlignedCharArray<EHScopeStack::ScopeStackAlignment, 8 * sizeof(void *)> CleanupBufferStack;
744  std::unique_ptr<char[]> CleanupBufferHeap;
745  size_t CleanupSize = Scope.getCleanupSize();
747 
748  if (CleanupSize <= sizeof(CleanupBufferStack)) {
749  memcpy(CleanupBufferStack.buffer, CleanupSource, CleanupSize);
750  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferStack.buffer);
751  } else {
752  CleanupBufferHeap.reset(new char[CleanupSize]);
753  memcpy(CleanupBufferHeap.get(), CleanupSource, CleanupSize);
754  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferHeap.get());
755  }
756 
757  EHScopeStack::Cleanup::Flags cleanupFlags;
758  if (Scope.isNormalCleanup())
759  cleanupFlags.setIsNormalCleanupKind();
760  if (Scope.isEHCleanup())
761  cleanupFlags.setIsEHCleanupKind();
762 
763  if (!RequiresNormalCleanup) {
764  destroyOptimisticNormalEntry(*this, Scope);
765  EHStack.popCleanup();
766  } else {
767  // If we have a fallthrough and no other need for the cleanup,
768  // emit it directly.
769  if (HasFallthrough && !HasPrebranchedFallthrough &&
770  !HasFixups && !HasExistingBranches) {
771 
772  destroyOptimisticNormalEntry(*this, Scope);
773  EHStack.popCleanup();
774 
775  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
776 
777  // Otherwise, the best approach is to thread everything through
778  // the cleanup block and then try to clean up after ourselves.
779  } else {
780  // Force the entry block to exist.
781  llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
782 
783  // I. Set up the fallthrough edge in.
784 
785  CGBuilderTy::InsertPoint savedInactiveFallthroughIP;
786 
787  // If there's a fallthrough, we need to store the cleanup
788  // destination index. For fall-throughs this is always zero.
789  if (HasFallthrough) {
790  if (!HasPrebranchedFallthrough)
791  Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
792 
793  // Otherwise, save and clear the IP if we don't have fallthrough
794  // because the cleanup is inactive.
795  } else if (FallthroughSource) {
796  assert(!IsActive && "source without fallthrough for active cleanup");
797  savedInactiveFallthroughIP = Builder.saveAndClearIP();
798  }
799 
800  // II. Emit the entry block. This implicitly branches to it if
801  // we have fallthrough. All the fixups and existing branches
802  // should already be branched to it.
803  EmitBlock(NormalEntry);
804 
805  // III. Figure out where we're going and build the cleanup
806  // epilogue.
807 
808  bool HasEnclosingCleanups =
809  (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
810 
811  // Compute the branch-through dest if we need it:
812  // - if there are branch-throughs threaded through the scope
813  // - if fall-through is a branch-through
814  // - if there are fixups that will be optimistically forwarded
815  // to the enclosing cleanup
816  llvm::BasicBlock *BranchThroughDest = nullptr;
817  if (Scope.hasBranchThroughs() ||
818  (FallthroughSource && FallthroughIsBranchThrough) ||
819  (HasFixups && HasEnclosingCleanups)) {
820  assert(HasEnclosingCleanups);
821  EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
822  BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
823  }
824 
825  llvm::BasicBlock *FallthroughDest = nullptr;
827 
828  // If there's exactly one branch-after and no other threads,
829  // we can route it without a switch.
830  if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
831  Scope.getNumBranchAfters() == 1) {
832  assert(!BranchThroughDest || !IsActive);
833 
834  // Clean up the possibly dead store to the cleanup dest slot.
835  llvm::Instruction *NormalCleanupDestSlot =
836  cast<llvm::Instruction>(getNormalCleanupDestSlot().getPointer());
837  if (NormalCleanupDestSlot->hasOneUse()) {
838  NormalCleanupDestSlot->user_back()->eraseFromParent();
839  NormalCleanupDestSlot->eraseFromParent();
840  NormalCleanupDest = Address::invalid();
841  }
842 
843  llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
844  InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
845 
846  // Build a switch-out if we need it:
847  // - if there are branch-afters threaded through the scope
848  // - if fall-through is a branch-after
849  // - if there are fixups that have nowhere left to go and
850  // so must be immediately resolved
851  } else if (Scope.getNumBranchAfters() ||
852  (HasFallthrough && !FallthroughIsBranchThrough) ||
853  (HasFixups && !HasEnclosingCleanups)) {
854 
855  llvm::BasicBlock *Default =
856  (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
857 
858  // TODO: base this on the number of branch-afters and fixups
859  const unsigned SwitchCapacity = 10;
860 
861  llvm::LoadInst *Load =
862  createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
863  nullptr);
864  llvm::SwitchInst *Switch =
865  llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
866 
867  InstsToAppend.push_back(Load);
868  InstsToAppend.push_back(Switch);
869 
870  // Branch-after fallthrough.
871  if (FallthroughSource && !FallthroughIsBranchThrough) {
872  FallthroughDest = createBasicBlock("cleanup.cont");
873  if (HasFallthrough)
874  Switch->addCase(Builder.getInt32(0), FallthroughDest);
875  }
876 
877  for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
878  Switch->addCase(Scope.getBranchAfterIndex(I),
879  Scope.getBranchAfterBlock(I));
880  }
881 
882  // If there aren't any enclosing cleanups, we can resolve all
883  // the fixups now.
884  if (HasFixups && !HasEnclosingCleanups)
885  ResolveAllBranchFixups(*this, Switch, NormalEntry);
886  } else {
887  // We should always have a branch-through destination in this case.
888  assert(BranchThroughDest);
889  InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
890  }
891 
892  // IV. Pop the cleanup and emit it.
893  EHStack.popCleanup();
894  assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
895 
896  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
897 
898  // Append the prepared cleanup prologue from above.
899  llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
900  for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
901  NormalExit->getInstList().push_back(InstsToAppend[I]);
902 
903  // Optimistically hope that any fixups will continue falling through.
904  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
905  I < E; ++I) {
906  BranchFixup &Fixup = EHStack.getBranchFixup(I);
907  if (!Fixup.Destination) continue;
908  if (!Fixup.OptimisticBranchBlock) {
909  createStoreInstBefore(Builder.getInt32(Fixup.DestinationIndex),
910  getNormalCleanupDestSlot(),
911  Fixup.InitialBranch);
912  Fixup.InitialBranch->setSuccessor(0, NormalEntry);
913  }
914  Fixup.OptimisticBranchBlock = NormalExit;
915  }
916 
917  // V. Set up the fallthrough edge out.
918 
919  // Case 1: a fallthrough source exists but doesn't branch to the
920  // cleanup because the cleanup is inactive.
921  if (!HasFallthrough && FallthroughSource) {
922  // Prebranched fallthrough was forwarded earlier.
923  // Non-prebranched fallthrough doesn't need to be forwarded.
924  // Either way, all we need to do is restore the IP we cleared before.
925  assert(!IsActive);
926  Builder.restoreIP(savedInactiveFallthroughIP);
927 
928  // Case 2: a fallthrough source exists and should branch to the
929  // cleanup, but we're not supposed to branch through to the next
930  // cleanup.
931  } else if (HasFallthrough && FallthroughDest) {
932  assert(!FallthroughIsBranchThrough);
933  EmitBlock(FallthroughDest);
934 
935  // Case 3: a fallthrough source exists and should branch to the
936  // cleanup and then through to the next.
937  } else if (HasFallthrough) {
938  // Everything is already set up for this.
939 
940  // Case 4: no fallthrough source exists.
941  } else {
942  Builder.ClearInsertionPoint();
943  }
944 
945  // VI. Assorted cleaning.
946 
947  // Check whether we can merge NormalEntry into a single predecessor.
948  // This might invalidate (non-IR) pointers to NormalEntry.
949  llvm::BasicBlock *NewNormalEntry =
950  SimplifyCleanupEntry(*this, NormalEntry);
951 
952  // If it did invalidate those pointers, and NormalEntry was the same
953  // as NormalExit, go back and patch up the fixups.
954  if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
955  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
956  I < E; ++I)
957  EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
958  }
959  }
960 
961  assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
962 
963  // Emit the EH cleanup if required.
964  if (RequiresEHCleanup) {
965  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
966 
967  EmitBlock(EHEntry);
968 
969  llvm::BasicBlock *NextAction = getEHDispatchBlock(EHParent);
970 
971  // Push a terminate scope or cleanupendpad scope around the potentially
972  // throwing cleanups. For funclet EH personalities, the cleanupendpad models
973  // program termination when cleanups throw.
974  bool PushedTerminate = false;
975  SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
976  CurrentFuncletPad);
977  llvm::CleanupPadInst *CPI = nullptr;
978 
979  const EHPersonality &Personality = EHPersonality::get(*this);
980  if (Personality.usesFuncletPads()) {
981  llvm::Value *ParentPad = CurrentFuncletPad;
982  if (!ParentPad)
983  ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
984  CurrentFuncletPad = CPI = Builder.CreateCleanupPad(ParentPad);
985  }
986 
987  // Non-MSVC personalities need to terminate when an EH cleanup throws.
988  if (!Personality.isMSVCPersonality()) {
989  EHStack.pushTerminate();
990  PushedTerminate = true;
991  }
992 
993  // We only actually emit the cleanup code if the cleanup is either
994  // active or was used before it was deactivated.
995  if (EHActiveFlag.isValid() || IsActive) {
996  cleanupFlags.setIsForEHCleanup();
997  EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
998  }
999 
1000  if (CPI)
1001  Builder.CreateCleanupRet(CPI, NextAction);
1002  else
1003  Builder.CreateBr(NextAction);
1004 
1005  // Leave the terminate scope.
1006  if (PushedTerminate)
1007  EHStack.popTerminate();
1008 
1009  Builder.restoreIP(SavedIP);
1010 
1011  SimplifyCleanupEntry(*this, EHEntry);
1012  }
1013 }
1014 
1015 /// isObviouslyBranchWithoutCleanups - Return true if a branch to the
1016 /// specified destination obviously has no cleanups to run. 'false' is always
1017 /// a conservatively correct answer for this method.
1019  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1020  && "stale jump destination");
1021 
1022  // Calculate the innermost active normal cleanup.
1023  EHScopeStack::stable_iterator TopCleanup =
1024  EHStack.getInnermostActiveNormalCleanup();
1025 
1026  // If we're not in an active normal cleanup scope, or if the
1027  // destination scope is within the innermost active normal cleanup
1028  // scope, we don't need to worry about fixups.
1029  if (TopCleanup == EHStack.stable_end() ||
1030  TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid
1031  return true;
1032 
1033  // Otherwise, we might need some cleanups.
1034  return false;
1035 }
1036 
1037 
1038 /// Terminate the current block by emitting a branch which might leave
1039 /// the current cleanup-protected scope. The target scope may not yet
1040 /// be known, in which case this will require a fixup.
1041 ///
1042 /// As a side-effect, this method clears the insertion point.
1044  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1045  && "stale jump destination");
1046 
1047  if (!HaveInsertPoint())
1048  return;
1049 
1050  // Create the branch.
1051  llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
1052 
1053  // Calculate the innermost active normal cleanup.
1055  TopCleanup = EHStack.getInnermostActiveNormalCleanup();
1056 
1057  // If we're not in an active normal cleanup scope, or if the
1058  // destination scope is within the innermost active normal cleanup
1059  // scope, we don't need to worry about fixups.
1060  if (TopCleanup == EHStack.stable_end() ||
1061  TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
1062  Builder.ClearInsertionPoint();
1063  return;
1064  }
1065 
1066  // If we can't resolve the destination cleanup scope, just add this
1067  // to the current cleanup scope as a branch fixup.
1068  if (!Dest.getScopeDepth().isValid()) {
1069  BranchFixup &Fixup = EHStack.addBranchFixup();
1070  Fixup.Destination = Dest.getBlock();
1071  Fixup.DestinationIndex = Dest.getDestIndex();
1072  Fixup.InitialBranch = BI;
1073  Fixup.OptimisticBranchBlock = nullptr;
1074 
1075  Builder.ClearInsertionPoint();
1076  return;
1077  }
1078 
1079  // Otherwise, thread through all the normal cleanups in scope.
1080 
1081  // Store the index at the start.
1082  llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
1083  createStoreInstBefore(Index, getNormalCleanupDestSlot(), BI);
1084 
1085  // Adjust BI to point to the first cleanup block.
1086  {
1088  cast<EHCleanupScope>(*EHStack.find(TopCleanup));
1089  BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
1090  }
1091 
1092  // Add this destination to all the scopes involved.
1093  EHScopeStack::stable_iterator I = TopCleanup;
1095  if (E.strictlyEncloses(I)) {
1096  while (true) {
1097  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
1098  assert(Scope.isNormalCleanup());
1099  I = Scope.getEnclosingNormalCleanup();
1100 
1101  // If this is the last cleanup we're propagating through, tell it
1102  // that there's a resolved jump moving through it.
1103  if (!E.strictlyEncloses(I)) {
1104  Scope.addBranchAfter(Index, Dest.getBlock());
1105  break;
1106  }
1107 
1108  // Otherwise, tell the scope that there's a jump propagating
1109  // through it. If this isn't new information, all the rest of
1110  // the work has been done before.
1111  if (!Scope.addBranchThrough(Dest.getBlock()))
1112  break;
1113  }
1114  }
1115 
1116  Builder.ClearInsertionPoint();
1117 }
1118 
1121  // If we needed a normal block for any reason, that counts.
1122  if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
1123  return true;
1124 
1125  // Check whether any enclosed cleanups were needed.
1127  I = EHStack.getInnermostNormalCleanup();
1128  I != C; ) {
1129  assert(C.strictlyEncloses(I));
1130  EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
1131  if (S.getNormalBlock()) return true;
1132  I = S.getEnclosingNormalCleanup();
1133  }
1134 
1135  return false;
1136 }
1137 
1138 static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
1140  // If we needed an EH block for any reason, that counts.
1141  if (EHStack.find(cleanup)->hasEHBranches())
1142  return true;
1143 
1144  // Check whether any enclosed cleanups were needed.
1146  i = EHStack.getInnermostEHScope(); i != cleanup; ) {
1147  assert(cleanup.strictlyEncloses(i));
1148 
1149  EHScope &scope = *EHStack.find(i);
1150  if (scope.hasEHBranches())
1151  return true;
1152 
1153  i = scope.getEnclosingEHScope();
1154  }
1155 
1156  return false;
1157 }
1158 
1162 };
1163 
1164 /// The given cleanup block is changing activation state. Configure a
1165 /// cleanup variable if necessary.
1166 ///
1167 /// It would be good if we had some way of determining if there were
1168 /// extra uses *after* the change-over point.
1172  llvm::Instruction *dominatingIP) {
1173  EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
1174 
1175  // We always need the flag if we're activating the cleanup in a
1176  // conditional context, because we have to assume that the current
1177  // location doesn't necessarily dominate the cleanup's code.
1178  bool isActivatedInConditional =
1179  (kind == ForActivation && CGF.isInConditionalBranch());
1180 
1181  bool needFlag = false;
1182 
1183  // Calculate whether the cleanup was used:
1184 
1185  // - as a normal cleanup
1186  if (Scope.isNormalCleanup() &&
1187  (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
1189  needFlag = true;
1190  }
1191 
1192  // - as an EH cleanup
1193  if (Scope.isEHCleanup() &&
1194  (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
1195  Scope.setTestFlagInEHCleanup();
1196  needFlag = true;
1197  }
1198 
1199  // If it hasn't yet been used as either, we're done.
1200  if (!needFlag) return;
1201 
1202  Address var = Scope.getActiveFlag();
1203  if (!var.isValid()) {
1204  var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), CharUnits::One(),
1205  "cleanup.isactive");
1206  Scope.setActiveFlag(var);
1207 
1208  assert(dominatingIP && "no existing variable and no dominating IP!");
1209 
1210  // Initialize to true or false depending on whether it was
1211  // active up to this point.
1212  llvm::Constant *value = CGF.Builder.getInt1(kind == ForDeactivation);
1213 
1214  // If we're in a conditional block, ignore the dominating IP and
1215  // use the outermost conditional branch.
1216  if (CGF.isInConditionalBranch()) {
1217  CGF.setBeforeOutermostConditional(value, var);
1218  } else {
1219  createStoreInstBefore(value, var, dominatingIP);
1220  }
1221  }
1222 
1223  CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
1224 }
1225 
1226 /// Activate a cleanup that was created in an inactivated state.
1228  llvm::Instruction *dominatingIP) {
1229  assert(C != EHStack.stable_end() && "activating bottom of stack?");
1230  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1231  assert(!Scope.isActive() && "double activation");
1232 
1233  SetupCleanupBlockActivation(*this, C, ForActivation, dominatingIP);
1234 
1235  Scope.setActive(true);
1236 }
1237 
1238 /// Deactive a cleanup that was created in an active state.
1240  llvm::Instruction *dominatingIP) {
1241  assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
1242  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1243  assert(Scope.isActive() && "double deactivation");
1244 
1245  // If it's the top of the stack, just pop it, but do so only if it belongs
1246  // to the current RunCleanupsScope.
1247  if (C == EHStack.stable_begin() &&
1248  CurrentCleanupScopeDepth.strictlyEncloses(C)) {
1249  // If it's a normal cleanup, we need to pretend that the
1250  // fallthrough is unreachable.
1251  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1252  PopCleanupBlock();
1253  Builder.restoreIP(SavedIP);
1254  return;
1255  }
1256 
1257  // Otherwise, follow the general case.
1258  SetupCleanupBlockActivation(*this, C, ForDeactivation, dominatingIP);
1259 
1260  Scope.setActive(false);
1261 }
1262 
1264  if (!NormalCleanupDest.isValid())
1265  NormalCleanupDest =
1266  CreateDefaultAlignTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
1267  return NormalCleanupDest;
1268 }
1269 
1270 /// Emits all the code to cause the given temporary to be cleaned up.
1272  QualType TempType,
1273  Address Ptr) {
1274  pushDestroy(NormalAndEHCleanup, Ptr, TempType, destroyCXXObject,
1275  /*useEHCleanup*/ true);
1276 }
bool isAggregate() const
Definition: CGValue.h:53
void pushTerminate()
Push a terminate handler on the stack.
Definition: CGCleanup.cpp:252
Address CreateStructGEP(Address Addr, unsigned Index, const llvm::Twine &Name="")
Definition: CGBuilder.h:178
static llvm::BasicBlock * CreateNormalEntry(CodeGenFunction &CGF, EHCleanupScope &Scope)
Definition: CGCleanup.cpp:505
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:1227
A (possibly-)qualified type.
Definition: Type.h:643
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:310
static void destroyOptimisticNormalEntry(CodeGenFunction &CGF, EHCleanupScope &scope)
We don&#39;t need a normal entry block for the given cleanup.
Definition: CGCleanup.cpp:604
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:292
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:2328
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:358
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
RangeSelector name(std::string ID)
Given a node with a "name", (like NamedDecl, DeclRefExpr or CxxCtorInitializer) selects the name&#39;s to...
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:555
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
long i
Definition: xmmintrin.h:1456
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:1018
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:1159
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:244
BranchFixup & getBranchFixup(unsigned I)
Definition: EHScopeStack.h:402
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:141
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:235
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:1138
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:304
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:320
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:119
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
#define V(N, I)
Definition: ASTContext.h:2907
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:378
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:202
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:417
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:1245
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:1239
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:1271
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:1119
static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit, llvm::BasicBlock *From, llvm::BasicBlock *To)
Definition: CGCleanup.cpp:580
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:227
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:263
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
static llvm::BasicBlock * SimplifyCleanupEntry(CodeGenFunction &CGF, llvm::BasicBlock *Entry)
Attempts to reduce a cleanup&#39;s entry block to a fallthrough.
Definition: CGCleanup.cpp:521
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:1169
stable_iterator getInnermostActiveNormalCleanup() const
Definition: CGCleanup.cpp:167
llvm::Value * getAggregatePointer() const
Definition: CGValue.h:75
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
EmitBlock - Emit the given block.
Definition: CGStmt.cpp:454
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:1043
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:644
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.