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CGCleanup.cpp
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1 //===--- CGCleanup.cpp - Bookkeeping and code emission for cleanups -------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains code dealing with the IR generation for cleanups
11 // and related information.
12 //
13 // A "cleanup" is a piece of code which needs to be executed whenever
14 // control transfers out of a particular scope. This can be
15 // conditionalized to occur only on exceptional control flow, only on
16 // normal control flow, or both.
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #include "CGCleanup.h"
21 #include "CodeGenFunction.h"
22 #include "llvm/Support/SaveAndRestore.h"
23 
24 using namespace clang;
25 using namespace CodeGen;
26 
28  if (rv.isScalar())
30  if (rv.isAggregate())
32  return true;
33 }
34 
37  if (rv.isScalar()) {
38  llvm::Value *V = rv.getScalarVal();
39 
40  // These automatically dominate and don't need to be saved.
42  return saved_type(V, ScalarLiteral);
43 
44  // Everything else needs an alloca.
45  Address addr =
46  CGF.CreateDefaultAlignTempAlloca(V->getType(), "saved-rvalue");
47  CGF.Builder.CreateStore(V, addr);
48  return saved_type(addr.getPointer(), ScalarAddress);
49  }
50 
51  if (rv.isComplex()) {
53  llvm::Type *ComplexTy =
54  llvm::StructType::get(V.first->getType(), V.second->getType());
55  Address addr = CGF.CreateDefaultAlignTempAlloca(ComplexTy, "saved-complex");
56  CGF.Builder.CreateStore(V.first,
57  CGF.Builder.CreateStructGEP(addr, 0, CharUnits()));
59  CGF.CGM.getDataLayout().getTypeAllocSize(V.first->getType()));
60  CGF.Builder.CreateStore(V.second,
61  CGF.Builder.CreateStructGEP(addr, 1, offset));
62  return saved_type(addr.getPointer(), ComplexAddress);
63  }
64 
65  assert(rv.isAggregate());
66  Address V = rv.getAggregateAddress(); // TODO: volatile?
67  if (!DominatingLLVMValue::needsSaving(V.getPointer()))
68  return saved_type(V.getPointer(), AggregateLiteral,
69  V.getAlignment().getQuantity());
70 
71  Address addr =
72  CGF.CreateTempAlloca(V.getType(), CGF.getPointerAlign(), "saved-rvalue");
73  CGF.Builder.CreateStore(V.getPointer(), addr);
74  return saved_type(addr.getPointer(), AggregateAddress,
75  V.getAlignment().getQuantity());
76 }
77 
78 /// Given a saved r-value produced by SaveRValue, perform the code
79 /// necessary to restore it to usability at the current insertion
80 /// point.
82  auto getSavingAddress = [&](llvm::Value *value) {
83  auto alignment = cast<llvm::AllocaInst>(value)->getAlignment();
84  return Address(value, CharUnits::fromQuantity(alignment));
85  };
86  switch (K) {
87  case ScalarLiteral:
88  return RValue::get(Value);
89  case ScalarAddress:
90  return RValue::get(CGF.Builder.CreateLoad(getSavingAddress(Value)));
91  case AggregateLiteral:
93  case AggregateAddress: {
94  auto addr = CGF.Builder.CreateLoad(getSavingAddress(Value));
96  }
97  case ComplexAddress: {
98  Address address = getSavingAddress(Value);
99  llvm::Value *real = CGF.Builder.CreateLoad(
100  CGF.Builder.CreateStructGEP(address, 0, CharUnits()));
102  CGF.CGM.getDataLayout().getTypeAllocSize(real->getType()));
103  llvm::Value *imag = CGF.Builder.CreateLoad(
104  CGF.Builder.CreateStructGEP(address, 1, offset));
105  return RValue::getComplex(real, imag);
106  }
107  }
108 
109  llvm_unreachable("bad saved r-value kind");
110 }
111 
112 /// Push an entry of the given size onto this protected-scope stack.
113 char *EHScopeStack::allocate(size_t Size) {
114  Size = llvm::alignTo(Size, ScopeStackAlignment);
115  if (!StartOfBuffer) {
116  unsigned Capacity = 1024;
117  while (Capacity < Size) Capacity *= 2;
118  StartOfBuffer = new char[Capacity];
119  StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
120  } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
121  unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
122  unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
123 
124  unsigned NewCapacity = CurrentCapacity;
125  do {
126  NewCapacity *= 2;
127  } while (NewCapacity < UsedCapacity + Size);
128 
129  char *NewStartOfBuffer = new char[NewCapacity];
130  char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
131  char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
132  memcpy(NewStartOfData, StartOfData, UsedCapacity);
133  delete [] StartOfBuffer;
134  StartOfBuffer = NewStartOfBuffer;
135  EndOfBuffer = NewEndOfBuffer;
136  StartOfData = NewStartOfData;
137  }
138 
139  assert(StartOfBuffer + Size <= StartOfData);
140  StartOfData -= Size;
141  return StartOfData;
142 }
143 
144 void EHScopeStack::deallocate(size_t Size) {
145  StartOfData += llvm::alignTo(Size, ScopeStackAlignment);
146 }
147 
149  EHScopeStack::stable_iterator Old) const {
150  for (EHScopeStack::iterator it = begin(); stabilize(it) != Old; it++) {
151  EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*it);
152  if (!cleanup || !cleanup->isLifetimeMarker())
153  return false;
154  }
155 
156  return true;
157 }
158 
160  for (stable_iterator si = getInnermostEHScope(); si != stable_end(); ) {
161  // Skip lifetime markers.
162  if (auto *cleanup = dyn_cast<EHCleanupScope>(&*find(si)))
163  if (cleanup->isLifetimeMarker()) {
164  si = cleanup->getEnclosingEHScope();
165  continue;
166  }
167  return true;
168  }
169 
170  return false;
171 }
172 
176  si != se; ) {
177  EHCleanupScope &cleanup = cast<EHCleanupScope>(*find(si));
178  if (cleanup.isActive()) return si;
179  si = cleanup.getEnclosingNormalCleanup();
180  }
181  return stable_end();
182 }
183 
184 
185 void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
186  char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
187  bool IsNormalCleanup = Kind & NormalCleanup;
188  bool IsEHCleanup = Kind & EHCleanup;
189  bool IsActive = !(Kind & InactiveCleanup);
190  bool IsLifetimeMarker = Kind & LifetimeMarker;
192  new (Buffer) EHCleanupScope(IsNormalCleanup,
193  IsEHCleanup,
194  IsActive,
195  Size,
196  BranchFixups.size(),
197  InnermostNormalCleanup,
198  InnermostEHScope);
199  if (IsNormalCleanup)
200  InnermostNormalCleanup = stable_begin();
201  if (IsEHCleanup)
202  InnermostEHScope = stable_begin();
203  if (IsLifetimeMarker)
204  Scope->setLifetimeMarker();
205 
206  return Scope->getCleanupBuffer();
207 }
208 
210  assert(!empty() && "popping exception stack when not empty");
211 
212  assert(isa<EHCleanupScope>(*begin()));
213  EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
214  InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
215  InnermostEHScope = Cleanup.getEnclosingEHScope();
216  deallocate(Cleanup.getAllocatedSize());
217 
218  // Destroy the cleanup.
219  Cleanup.Destroy();
220 
221  // Check whether we can shrink the branch-fixups stack.
222  if (!BranchFixups.empty()) {
223  // If we no longer have any normal cleanups, all the fixups are
224  // complete.
225  if (!hasNormalCleanups())
226  BranchFixups.clear();
227 
228  // Otherwise we can still trim out unnecessary nulls.
229  else
230  popNullFixups();
231  }
232 }
233 
235  assert(getInnermostEHScope() == stable_end());
236  char *buffer = allocate(EHFilterScope::getSizeForNumFilters(numFilters));
237  EHFilterScope *filter = new (buffer) EHFilterScope(numFilters);
238  InnermostEHScope = stable_begin();
239  return filter;
240 }
241 
243  assert(!empty() && "popping exception stack when not empty");
244 
245  EHFilterScope &filter = cast<EHFilterScope>(*begin());
247 
248  InnermostEHScope = filter.getEnclosingEHScope();
249 }
250 
251 EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) {
252  char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers));
253  EHCatchScope *scope =
254  new (buffer) EHCatchScope(numHandlers, InnermostEHScope);
255  InnermostEHScope = stable_begin();
256  return scope;
257 }
258 
260  char *Buffer = allocate(EHTerminateScope::getSize());
261  new (Buffer) EHTerminateScope(InnermostEHScope);
262  InnermostEHScope = stable_begin();
263 }
264 
265 /// Remove any 'null' fixups on the stack. However, we can't pop more
266 /// fixups than the fixup depth on the innermost normal cleanup, or
267 /// else fixups that we try to add to that cleanup will end up in the
268 /// wrong place. We *could* try to shrink fixup depths, but that's
269 /// actually a lot of work for little benefit.
271  // We expect this to only be called when there's still an innermost
272  // normal cleanup; otherwise there really shouldn't be any fixups.
273  assert(hasNormalCleanups());
274 
275  EHScopeStack::iterator it = find(InnermostNormalCleanup);
276  unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
277  assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
278 
279  while (BranchFixups.size() > MinSize &&
280  BranchFixups.back().Destination == nullptr)
281  BranchFixups.pop_back();
282 }
283 
285  // Create a variable to decide whether the cleanup needs to be run.
286  Address active = CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(),
287  "cleanup.cond");
288 
289  // Initialize it to false at a site that's guaranteed to be run
290  // before each evaluation.
291  setBeforeOutermostConditional(Builder.getFalse(), active);
292 
293  // Initialize it to true at the current location.
294  Builder.CreateStore(Builder.getTrue(), active);
295 
296  // Set that as the active flag in the cleanup.
297  EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
298  assert(!cleanup.hasActiveFlag() && "cleanup already has active flag?");
299  cleanup.setActiveFlag(active);
300 
301  if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
302  if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
303 }
304 
305 void EHScopeStack::Cleanup::anchor() {}
306 
307 static void createStoreInstBefore(llvm::Value *value, Address addr,
308  llvm::Instruction *beforeInst) {
309  auto store = new llvm::StoreInst(value, addr.getPointer(), beforeInst);
310  store->setAlignment(addr.getAlignment().getQuantity());
311 }
312 
313 static llvm::LoadInst *createLoadInstBefore(Address addr, const Twine &name,
314  llvm::Instruction *beforeInst) {
315  auto load = new llvm::LoadInst(addr.getPointer(), name, beforeInst);
316  load->setAlignment(addr.getAlignment().getQuantity());
317  return load;
318 }
319 
320 /// All the branch fixups on the EH stack have propagated out past the
321 /// outermost normal cleanup; resolve them all by adding cases to the
322 /// given switch instruction.
324  llvm::SwitchInst *Switch,
325  llvm::BasicBlock *CleanupEntry) {
326  llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
327 
328  for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
329  // Skip this fixup if its destination isn't set.
330  BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
331  if (Fixup.Destination == nullptr) continue;
332 
333  // If there isn't an OptimisticBranchBlock, then InitialBranch is
334  // still pointing directly to its destination; forward it to the
335  // appropriate cleanup entry. This is required in the specific
336  // case of
337  // { std::string s; goto lbl; }
338  // lbl:
339  // i.e. where there's an unresolved fixup inside a single cleanup
340  // entry which we're currently popping.
341  if (Fixup.OptimisticBranchBlock == nullptr) {
342  createStoreInstBefore(CGF.Builder.getInt32(Fixup.DestinationIndex),
344  Fixup.InitialBranch);
345  Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
346  }
347 
348  // Don't add this case to the switch statement twice.
349  if (!CasesAdded.insert(Fixup.Destination).second)
350  continue;
351 
352  Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
353  Fixup.Destination);
354  }
355 
356  CGF.EHStack.clearFixups();
357 }
358 
359 /// Transitions the terminator of the given exit-block of a cleanup to
360 /// be a cleanup switch.
361 static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
362  llvm::BasicBlock *Block) {
363  // If it's a branch, turn it into a switch whose default
364  // destination is its original target.
365  llvm::TerminatorInst *Term = Block->getTerminator();
366  assert(Term && "can't transition block without terminator");
367 
368  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
369  assert(Br->isUnconditional());
371  "cleanup.dest", Term);
372  llvm::SwitchInst *Switch =
373  llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
374  Br->eraseFromParent();
375  return Switch;
376  } else {
377  return cast<llvm::SwitchInst>(Term);
378  }
379 }
380 
381 void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
382  assert(Block && "resolving a null target block");
383  if (!EHStack.getNumBranchFixups()) return;
384 
385  assert(EHStack.hasNormalCleanups() &&
386  "branch fixups exist with no normal cleanups on stack");
387 
388  llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
389  bool ResolvedAny = false;
390 
391  for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
392  // Skip this fixup if its destination doesn't match.
393  BranchFixup &Fixup = EHStack.getBranchFixup(I);
394  if (Fixup.Destination != Block) continue;
395 
396  Fixup.Destination = nullptr;
397  ResolvedAny = true;
398 
399  // If it doesn't have an optimistic branch block, LatestBranch is
400  // already pointing to the right place.
401  llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
402  if (!BranchBB)
403  continue;
404 
405  // Don't process the same optimistic branch block twice.
406  if (!ModifiedOptimisticBlocks.insert(BranchBB).second)
407  continue;
408 
409  llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
410 
411  // Add a case to the switch.
412  Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
413  }
414 
415  if (ResolvedAny)
416  EHStack.popNullFixups();
417 }
418 
419 /// Pops cleanup blocks until the given savepoint is reached.
422  std::initializer_list<llvm::Value **> ValuesToReload) {
423  assert(Old.isValid());
424 
425  bool HadBranches = false;
426  while (EHStack.stable_begin() != Old) {
427  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
428  HadBranches |= Scope.hasBranches();
429 
430  // As long as Old strictly encloses the scope's enclosing normal
431  // cleanup, we're going to emit another normal cleanup which
432  // fallthrough can propagate through.
433  bool FallThroughIsBranchThrough =
435 
436  PopCleanupBlock(FallThroughIsBranchThrough);
437  }
438 
439  // If we didn't have any branches, the insertion point before cleanups must
440  // dominate the current insertion point and we don't need to reload any
441  // values.
442  if (!HadBranches)
443  return;
444 
445  // Spill and reload all values that the caller wants to be live at the current
446  // insertion point.
447  for (llvm::Value **ReloadedValue : ValuesToReload) {
448  auto *Inst = dyn_cast_or_null<llvm::Instruction>(*ReloadedValue);
449  if (!Inst)
450  continue;
451 
452  // Don't spill static allocas, they dominate all cleanups. These are created
453  // by binding a reference to a local variable or temporary.
454  auto *AI = dyn_cast<llvm::AllocaInst>(Inst);
455  if (AI && AI->isStaticAlloca())
456  continue;
457 
458  Address Tmp =
459  CreateDefaultAlignTempAlloca(Inst->getType(), "tmp.exprcleanup");
460 
461  // Find an insertion point after Inst and spill it to the temporary.
462  llvm::BasicBlock::iterator InsertBefore;
463  if (auto *Invoke = dyn_cast<llvm::InvokeInst>(Inst))
464  InsertBefore = Invoke->getNormalDest()->getFirstInsertionPt();
465  else
466  InsertBefore = std::next(Inst->getIterator());
467  CGBuilderTy(CGM, &*InsertBefore).CreateStore(Inst, Tmp);
468 
469  // Reload the value at the current insertion point.
470  *ReloadedValue = Builder.CreateLoad(Tmp);
471  }
472 }
473 
474 /// Pops cleanup blocks until the given savepoint is reached, then add the
475 /// cleanups from the given savepoint in the lifetime-extended cleanups stack.
477  EHScopeStack::stable_iterator Old, size_t OldLifetimeExtendedSize,
478  std::initializer_list<llvm::Value **> ValuesToReload) {
479  PopCleanupBlocks(Old, ValuesToReload);
480 
481  // Move our deferred cleanups onto the EH stack.
482  for (size_t I = OldLifetimeExtendedSize,
483  E = LifetimeExtendedCleanupStack.size(); I != E; /**/) {
484  // Alignment should be guaranteed by the vptrs in the individual cleanups.
485  assert((I % alignof(LifetimeExtendedCleanupHeader) == 0) &&
486  "misaligned cleanup stack entry");
487 
489  reinterpret_cast<LifetimeExtendedCleanupHeader&>(
490  LifetimeExtendedCleanupStack[I]);
491  I += sizeof(Header);
492 
493  EHStack.pushCopyOfCleanup(Header.getKind(),
494  &LifetimeExtendedCleanupStack[I],
495  Header.getSize());
496  I += Header.getSize();
497  }
498  LifetimeExtendedCleanupStack.resize(OldLifetimeExtendedSize);
499 }
500 
501 static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
503  assert(Scope.isNormalCleanup());
504  llvm::BasicBlock *Entry = Scope.getNormalBlock();
505  if (!Entry) {
506  Entry = CGF.createBasicBlock("cleanup");
507  Scope.setNormalBlock(Entry);
508  }
509  return Entry;
510 }
511 
512 /// Attempts to reduce a cleanup's entry block to a fallthrough. This
513 /// is basically llvm::MergeBlockIntoPredecessor, except
514 /// simplified/optimized for the tighter constraints on cleanup blocks.
515 ///
516 /// Returns the new block, whatever it is.
517 static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
518  llvm::BasicBlock *Entry) {
519  llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
520  if (!Pred) return Entry;
521 
522  llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
523  if (!Br || Br->isConditional()) return Entry;
524  assert(Br->getSuccessor(0) == Entry);
525 
526  // If we were previously inserting at the end of the cleanup entry
527  // block, we'll need to continue inserting at the end of the
528  // predecessor.
529  bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
530  assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
531 
532  // Kill the branch.
533  Br->eraseFromParent();
534 
535  // Replace all uses of the entry with the predecessor, in case there
536  // are phis in the cleanup.
537  Entry->replaceAllUsesWith(Pred);
538 
539  // Merge the blocks.
540  Pred->getInstList().splice(Pred->end(), Entry->getInstList());
541 
542  // Kill the entry block.
543  Entry->eraseFromParent();
544 
545  if (WasInsertBlock)
546  CGF.Builder.SetInsertPoint(Pred);
547 
548  return Pred;
549 }
550 
551 static void EmitCleanup(CodeGenFunction &CGF,
554  Address ActiveFlag) {
555  // If there's an active flag, load it and skip the cleanup if it's
556  // false.
557  llvm::BasicBlock *ContBB = nullptr;
558  if (ActiveFlag.isValid()) {
559  ContBB = CGF.createBasicBlock("cleanup.done");
560  llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
561  llvm::Value *IsActive
562  = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
563  CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
564  CGF.EmitBlock(CleanupBB);
565  }
566 
567  // Ask the cleanup to emit itself.
568  Fn->Emit(CGF, flags);
569  assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
570 
571  // Emit the continuation block if there was an active flag.
572  if (ActiveFlag.isValid())
573  CGF.EmitBlock(ContBB);
574 }
575 
576 static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
577  llvm::BasicBlock *From,
578  llvm::BasicBlock *To) {
579  // Exit is the exit block of a cleanup, so it always terminates in
580  // an unconditional branch or a switch.
581  llvm::TerminatorInst *Term = Exit->getTerminator();
582 
583  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
584  assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
585  Br->setSuccessor(0, To);
586  } else {
587  llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
588  for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
589  if (Switch->getSuccessor(I) == From)
590  Switch->setSuccessor(I, To);
591  }
592 }
593 
594 /// We don't need a normal entry block for the given cleanup.
595 /// Optimistic fixup branches can cause these blocks to come into
596 /// existence anyway; if so, destroy it.
597 ///
598 /// The validity of this transformation is very much specific to the
599 /// exact ways in which we form branches to cleanup entries.
601  EHCleanupScope &scope) {
602  llvm::BasicBlock *entry = scope.getNormalBlock();
603  if (!entry) return;
604 
605  // Replace all the uses with unreachable.
606  llvm::BasicBlock *unreachableBB = CGF.getUnreachableBlock();
607  for (llvm::BasicBlock::use_iterator
608  i = entry->use_begin(), e = entry->use_end(); i != e; ) {
609  llvm::Use &use = *i;
610  ++i;
611 
612  use.set(unreachableBB);
613 
614  // The only uses should be fixup switches.
615  llvm::SwitchInst *si = cast<llvm::SwitchInst>(use.getUser());
616  if (si->getNumCases() == 1 && si->getDefaultDest() == unreachableBB) {
617  // Replace the switch with a branch.
618  llvm::BranchInst::Create(si->case_begin()->getCaseSuccessor(), si);
619 
620  // The switch operand is a load from the cleanup-dest alloca.
621  llvm::LoadInst *condition = cast<llvm::LoadInst>(si->getCondition());
622 
623  // Destroy the switch.
624  si->eraseFromParent();
625 
626  // Destroy the load.
627  assert(condition->getOperand(0) == CGF.NormalCleanupDest);
628  assert(condition->use_empty());
629  condition->eraseFromParent();
630  }
631  }
632 
633  assert(entry->use_empty());
634  delete entry;
635 }
636 
637 /// Pops a cleanup block. If the block includes a normal cleanup, the
638 /// current insertion point is threaded through the cleanup, as are
639 /// any branch fixups on the cleanup.
640 void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
641  assert(!EHStack.empty() && "cleanup stack is empty!");
642  assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
643  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
644  assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
645 
646  // Remember activation information.
647  bool IsActive = Scope.isActive();
648  Address NormalActiveFlag =
650  : Address::invalid();
651  Address EHActiveFlag =
652  Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag()
653  : Address::invalid();
654 
655  // Check whether we need an EH cleanup. This is only true if we've
656  // generated a lazy EH cleanup block.
657  llvm::BasicBlock *EHEntry = Scope.getCachedEHDispatchBlock();
658  assert(Scope.hasEHBranches() == (EHEntry != nullptr));
659  bool RequiresEHCleanup = (EHEntry != nullptr);
661 
662  // Check the three conditions which might require a normal cleanup:
663 
664  // - whether there are branch fix-ups through this cleanup
665  unsigned FixupDepth = Scope.getFixupDepth();
666  bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
667 
668  // - whether there are branch-throughs or branch-afters
669  bool HasExistingBranches = Scope.hasBranches();
670 
671  // - whether there's a fallthrough
672  llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
673  bool HasFallthrough = (FallthroughSource != nullptr && IsActive);
674 
675  // Branch-through fall-throughs leave the insertion point set to the
676  // end of the last cleanup, which points to the current scope. The
677  // rest of IR gen doesn't need to worry about this; it only happens
678  // during the execution of PopCleanupBlocks().
679  bool HasPrebranchedFallthrough =
680  (FallthroughSource && FallthroughSource->getTerminator());
681 
682  // If this is a normal cleanup, then having a prebranched
683  // fallthrough implies that the fallthrough source unconditionally
684  // jumps here.
685  assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
686  (Scope.getNormalBlock() &&
687  FallthroughSource->getTerminator()->getSuccessor(0)
688  == Scope.getNormalBlock()));
689 
690  bool RequiresNormalCleanup = false;
691  if (Scope.isNormalCleanup() &&
692  (HasFixups || HasExistingBranches || HasFallthrough)) {
693  RequiresNormalCleanup = true;
694  }
695 
696  // If we have a prebranched fallthrough into an inactive normal
697  // cleanup, rewrite it so that it leads to the appropriate place.
698  if (Scope.isNormalCleanup() && HasPrebranchedFallthrough && !IsActive) {
699  llvm::BasicBlock *prebranchDest;
700 
701  // If the prebranch is semantically branching through the next
702  // cleanup, just forward it to the next block, leaving the
703  // insertion point in the prebranched block.
704  if (FallthroughIsBranchThrough) {
705  EHScope &enclosing = *EHStack.find(Scope.getEnclosingNormalCleanup());
706  prebranchDest = CreateNormalEntry(*this, cast<EHCleanupScope>(enclosing));
707 
708  // Otherwise, we need to make a new block. If the normal cleanup
709  // isn't being used at all, we could actually reuse the normal
710  // entry block, but this is simpler, and it avoids conflicts with
711  // dead optimistic fixup branches.
712  } else {
713  prebranchDest = createBasicBlock("forwarded-prebranch");
714  EmitBlock(prebranchDest);
715  }
716 
717  llvm::BasicBlock *normalEntry = Scope.getNormalBlock();
718  assert(normalEntry && !normalEntry->use_empty());
719 
720  ForwardPrebranchedFallthrough(FallthroughSource,
721  normalEntry, prebranchDest);
722  }
723 
724  // If we don't need the cleanup at all, we're done.
725  if (!RequiresNormalCleanup && !RequiresEHCleanup) {
726  destroyOptimisticNormalEntry(*this, Scope);
727  EHStack.popCleanup(); // safe because there are no fixups
728  assert(EHStack.getNumBranchFixups() == 0 ||
729  EHStack.hasNormalCleanups());
730  return;
731  }
732 
733  // Copy the cleanup emission data out. This uses either a stack
734  // array or malloc'd memory, depending on the size, which is
735  // behavior that SmallVector would provide, if we could use it
736  // here. Unfortunately, if you ask for a SmallVector<char>, the
737  // alignment isn't sufficient.
738  auto *CleanupSource = reinterpret_cast<char *>(Scope.getCleanupBuffer());
739  llvm::AlignedCharArray<EHScopeStack::ScopeStackAlignment, 8 * sizeof(void *)> CleanupBufferStack;
740  std::unique_ptr<char[]> CleanupBufferHeap;
741  size_t CleanupSize = Scope.getCleanupSize();
743 
744  if (CleanupSize <= sizeof(CleanupBufferStack)) {
745  memcpy(CleanupBufferStack.buffer, CleanupSource, CleanupSize);
746  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferStack.buffer);
747  } else {
748  CleanupBufferHeap.reset(new char[CleanupSize]);
749  memcpy(CleanupBufferHeap.get(), CleanupSource, CleanupSize);
750  Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferHeap.get());
751  }
752 
753  EHScopeStack::Cleanup::Flags cleanupFlags;
754  if (Scope.isNormalCleanup())
755  cleanupFlags.setIsNormalCleanupKind();
756  if (Scope.isEHCleanup())
757  cleanupFlags.setIsEHCleanupKind();
758 
759  if (!RequiresNormalCleanup) {
760  destroyOptimisticNormalEntry(*this, Scope);
761  EHStack.popCleanup();
762  } else {
763  // If we have a fallthrough and no other need for the cleanup,
764  // emit it directly.
765  if (HasFallthrough && !HasPrebranchedFallthrough &&
766  !HasFixups && !HasExistingBranches) {
767 
768  destroyOptimisticNormalEntry(*this, Scope);
769  EHStack.popCleanup();
770 
771  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
772 
773  // Otherwise, the best approach is to thread everything through
774  // the cleanup block and then try to clean up after ourselves.
775  } else {
776  // Force the entry block to exist.
777  llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
778 
779  // I. Set up the fallthrough edge in.
780 
781  CGBuilderTy::InsertPoint savedInactiveFallthroughIP;
782 
783  // If there's a fallthrough, we need to store the cleanup
784  // destination index. For fall-throughs this is always zero.
785  if (HasFallthrough) {
786  if (!HasPrebranchedFallthrough)
787  Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
788 
789  // Otherwise, save and clear the IP if we don't have fallthrough
790  // because the cleanup is inactive.
791  } else if (FallthroughSource) {
792  assert(!IsActive && "source without fallthrough for active cleanup");
793  savedInactiveFallthroughIP = Builder.saveAndClearIP();
794  }
795 
796  // II. Emit the entry block. This implicitly branches to it if
797  // we have fallthrough. All the fixups and existing branches
798  // should already be branched to it.
799  EmitBlock(NormalEntry);
800 
801  // III. Figure out where we're going and build the cleanup
802  // epilogue.
803 
804  bool HasEnclosingCleanups =
805  (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
806 
807  // Compute the branch-through dest if we need it:
808  // - if there are branch-throughs threaded through the scope
809  // - if fall-through is a branch-through
810  // - if there are fixups that will be optimistically forwarded
811  // to the enclosing cleanup
812  llvm::BasicBlock *BranchThroughDest = nullptr;
813  if (Scope.hasBranchThroughs() ||
814  (FallthroughSource && FallthroughIsBranchThrough) ||
815  (HasFixups && HasEnclosingCleanups)) {
816  assert(HasEnclosingCleanups);
817  EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
818  BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
819  }
820 
821  llvm::BasicBlock *FallthroughDest = nullptr;
823 
824  // If there's exactly one branch-after and no other threads,
825  // we can route it without a switch.
826  if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
827  Scope.getNumBranchAfters() == 1) {
828  assert(!BranchThroughDest || !IsActive);
829 
830  // Clean up the possibly dead store to the cleanup dest slot.
831  llvm::Instruction *NormalCleanupDestSlot =
832  cast<llvm::Instruction>(getNormalCleanupDestSlot().getPointer());
833  if (NormalCleanupDestSlot->hasOneUse()) {
834  NormalCleanupDestSlot->user_back()->eraseFromParent();
835  NormalCleanupDestSlot->eraseFromParent();
836  NormalCleanupDest = nullptr;
837  }
838 
839  llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
840  InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
841 
842  // Build a switch-out if we need it:
843  // - if there are branch-afters threaded through the scope
844  // - if fall-through is a branch-after
845  // - if there are fixups that have nowhere left to go and
846  // so must be immediately resolved
847  } else if (Scope.getNumBranchAfters() ||
848  (HasFallthrough && !FallthroughIsBranchThrough) ||
849  (HasFixups && !HasEnclosingCleanups)) {
850 
851  llvm::BasicBlock *Default =
852  (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
853 
854  // TODO: base this on the number of branch-afters and fixups
855  const unsigned SwitchCapacity = 10;
856 
857  llvm::LoadInst *Load =
858  createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
859  nullptr);
860  llvm::SwitchInst *Switch =
861  llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
862 
863  InstsToAppend.push_back(Load);
864  InstsToAppend.push_back(Switch);
865 
866  // Branch-after fallthrough.
867  if (FallthroughSource && !FallthroughIsBranchThrough) {
868  FallthroughDest = createBasicBlock("cleanup.cont");
869  if (HasFallthrough)
870  Switch->addCase(Builder.getInt32(0), FallthroughDest);
871  }
872 
873  for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
874  Switch->addCase(Scope.getBranchAfterIndex(I),
875  Scope.getBranchAfterBlock(I));
876  }
877 
878  // If there aren't any enclosing cleanups, we can resolve all
879  // the fixups now.
880  if (HasFixups && !HasEnclosingCleanups)
881  ResolveAllBranchFixups(*this, Switch, NormalEntry);
882  } else {
883  // We should always have a branch-through destination in this case.
884  assert(BranchThroughDest);
885  InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
886  }
887 
888  // IV. Pop the cleanup and emit it.
889  EHStack.popCleanup();
890  assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
891 
892  EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
893 
894  // Append the prepared cleanup prologue from above.
895  llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
896  for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
897  NormalExit->getInstList().push_back(InstsToAppend[I]);
898 
899  // Optimistically hope that any fixups will continue falling through.
900  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
901  I < E; ++I) {
902  BranchFixup &Fixup = EHStack.getBranchFixup(I);
903  if (!Fixup.Destination) continue;
904  if (!Fixup.OptimisticBranchBlock) {
905  createStoreInstBefore(Builder.getInt32(Fixup.DestinationIndex),
906  getNormalCleanupDestSlot(),
907  Fixup.InitialBranch);
908  Fixup.InitialBranch->setSuccessor(0, NormalEntry);
909  }
910  Fixup.OptimisticBranchBlock = NormalExit;
911  }
912 
913  // V. Set up the fallthrough edge out.
914 
915  // Case 1: a fallthrough source exists but doesn't branch to the
916  // cleanup because the cleanup is inactive.
917  if (!HasFallthrough && FallthroughSource) {
918  // Prebranched fallthrough was forwarded earlier.
919  // Non-prebranched fallthrough doesn't need to be forwarded.
920  // Either way, all we need to do is restore the IP we cleared before.
921  assert(!IsActive);
922  Builder.restoreIP(savedInactiveFallthroughIP);
923 
924  // Case 2: a fallthrough source exists and should branch to the
925  // cleanup, but we're not supposed to branch through to the next
926  // cleanup.
927  } else if (HasFallthrough && FallthroughDest) {
928  assert(!FallthroughIsBranchThrough);
929  EmitBlock(FallthroughDest);
930 
931  // Case 3: a fallthrough source exists and should branch to the
932  // cleanup and then through to the next.
933  } else if (HasFallthrough) {
934  // Everything is already set up for this.
935 
936  // Case 4: no fallthrough source exists.
937  } else {
938  Builder.ClearInsertionPoint();
939  }
940 
941  // VI. Assorted cleaning.
942 
943  // Check whether we can merge NormalEntry into a single predecessor.
944  // This might invalidate (non-IR) pointers to NormalEntry.
945  llvm::BasicBlock *NewNormalEntry =
946  SimplifyCleanupEntry(*this, NormalEntry);
947 
948  // If it did invalidate those pointers, and NormalEntry was the same
949  // as NormalExit, go back and patch up the fixups.
950  if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
951  for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
952  I < E; ++I)
953  EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
954  }
955  }
956 
957  assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
958 
959  // Emit the EH cleanup if required.
960  if (RequiresEHCleanup) {
961  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
962 
963  EmitBlock(EHEntry);
964 
965  llvm::BasicBlock *NextAction = getEHDispatchBlock(EHParent);
966 
967  // Push a terminate scope or cleanupendpad scope around the potentially
968  // throwing cleanups. For funclet EH personalities, the cleanupendpad models
969  // program termination when cleanups throw.
970  bool PushedTerminate = false;
971  SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
972  CurrentFuncletPad);
973  llvm::CleanupPadInst *CPI = nullptr;
974  if (!EHPersonality::get(*this).usesFuncletPads()) {
975  EHStack.pushTerminate();
976  PushedTerminate = true;
977  } else {
978  llvm::Value *ParentPad = CurrentFuncletPad;
979  if (!ParentPad)
980  ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
981  CurrentFuncletPad = CPI = Builder.CreateCleanupPad(ParentPad);
982  }
983 
984  // We only actually emit the cleanup code if the cleanup is either
985  // active or was used before it was deactivated.
986  if (EHActiveFlag.isValid() || IsActive) {
987  cleanupFlags.setIsForEHCleanup();
988  EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
989  }
990 
991  if (CPI)
992  Builder.CreateCleanupRet(CPI, NextAction);
993  else
994  Builder.CreateBr(NextAction);
995 
996  // Leave the terminate scope.
997  if (PushedTerminate)
998  EHStack.popTerminate();
999 
1000  Builder.restoreIP(SavedIP);
1001 
1002  SimplifyCleanupEntry(*this, EHEntry);
1003  }
1004 }
1005 
1006 /// isObviouslyBranchWithoutCleanups - Return true if a branch to the
1007 /// specified destination obviously has no cleanups to run. 'false' is always
1008 /// a conservatively correct answer for this method.
1010  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1011  && "stale jump destination");
1012 
1013  // Calculate the innermost active normal cleanup.
1014  EHScopeStack::stable_iterator TopCleanup =
1015  EHStack.getInnermostActiveNormalCleanup();
1016 
1017  // If we're not in an active normal cleanup scope, or if the
1018  // destination scope is within the innermost active normal cleanup
1019  // scope, we don't need to worry about fixups.
1020  if (TopCleanup == EHStack.stable_end() ||
1021  TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid
1022  return true;
1023 
1024  // Otherwise, we might need some cleanups.
1025  return false;
1026 }
1027 
1028 
1029 /// Terminate the current block by emitting a branch which might leave
1030 /// the current cleanup-protected scope. The target scope may not yet
1031 /// be known, in which case this will require a fixup.
1032 ///
1033 /// As a side-effect, this method clears the insertion point.
1035  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1036  && "stale jump destination");
1037 
1038  if (!HaveInsertPoint())
1039  return;
1040 
1041  // Create the branch.
1042  llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
1043 
1044  // Calculate the innermost active normal cleanup.
1046  TopCleanup = EHStack.getInnermostActiveNormalCleanup();
1047 
1048  // If we're not in an active normal cleanup scope, or if the
1049  // destination scope is within the innermost active normal cleanup
1050  // scope, we don't need to worry about fixups.
1051  if (TopCleanup == EHStack.stable_end() ||
1052  TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
1053  Builder.ClearInsertionPoint();
1054  return;
1055  }
1056 
1057  // If we can't resolve the destination cleanup scope, just add this
1058  // to the current cleanup scope as a branch fixup.
1059  if (!Dest.getScopeDepth().isValid()) {
1060  BranchFixup &Fixup = EHStack.addBranchFixup();
1061  Fixup.Destination = Dest.getBlock();
1062  Fixup.DestinationIndex = Dest.getDestIndex();
1063  Fixup.InitialBranch = BI;
1064  Fixup.OptimisticBranchBlock = nullptr;
1065 
1066  Builder.ClearInsertionPoint();
1067  return;
1068  }
1069 
1070  // Otherwise, thread through all the normal cleanups in scope.
1071 
1072  // Store the index at the start.
1073  llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
1074  createStoreInstBefore(Index, getNormalCleanupDestSlot(), BI);
1075 
1076  // Adjust BI to point to the first cleanup block.
1077  {
1079  cast<EHCleanupScope>(*EHStack.find(TopCleanup));
1080  BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
1081  }
1082 
1083  // Add this destination to all the scopes involved.
1084  EHScopeStack::stable_iterator I = TopCleanup;
1086  if (E.strictlyEncloses(I)) {
1087  while (true) {
1088  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
1089  assert(Scope.isNormalCleanup());
1090  I = Scope.getEnclosingNormalCleanup();
1091 
1092  // If this is the last cleanup we're propagating through, tell it
1093  // that there's a resolved jump moving through it.
1094  if (!E.strictlyEncloses(I)) {
1095  Scope.addBranchAfter(Index, Dest.getBlock());
1096  break;
1097  }
1098 
1099  // Otherwise, tell the scope that there's a jump propagating
1100  // through it. If this isn't new information, all the rest of
1101  // the work has been done before.
1102  if (!Scope.addBranchThrough(Dest.getBlock()))
1103  break;
1104  }
1105  }
1106 
1107  Builder.ClearInsertionPoint();
1108 }
1109 
1112  // If we needed a normal block for any reason, that counts.
1113  if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
1114  return true;
1115 
1116  // Check whether any enclosed cleanups were needed.
1118  I = EHStack.getInnermostNormalCleanup();
1119  I != C; ) {
1120  assert(C.strictlyEncloses(I));
1121  EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
1122  if (S.getNormalBlock()) return true;
1123  I = S.getEnclosingNormalCleanup();
1124  }
1125 
1126  return false;
1127 }
1128 
1129 static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
1131  // If we needed an EH block for any reason, that counts.
1132  if (EHStack.find(cleanup)->hasEHBranches())
1133  return true;
1134 
1135  // Check whether any enclosed cleanups were needed.
1137  i = EHStack.getInnermostEHScope(); i != cleanup; ) {
1138  assert(cleanup.strictlyEncloses(i));
1139 
1140  EHScope &scope = *EHStack.find(i);
1141  if (scope.hasEHBranches())
1142  return true;
1143 
1144  i = scope.getEnclosingEHScope();
1145  }
1146 
1147  return false;
1148 }
1149 
1153 };
1154 
1155 /// The given cleanup block is changing activation state. Configure a
1156 /// cleanup variable if necessary.
1157 ///
1158 /// It would be good if we had some way of determining if there were
1159 /// extra uses *after* the change-over point.
1163  llvm::Instruction *dominatingIP) {
1164  EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
1165 
1166  // We always need the flag if we're activating the cleanup in a
1167  // conditional context, because we have to assume that the current
1168  // location doesn't necessarily dominate the cleanup's code.
1169  bool isActivatedInConditional =
1170  (kind == ForActivation && CGF.isInConditionalBranch());
1171 
1172  bool needFlag = false;
1173 
1174  // Calculate whether the cleanup was used:
1175 
1176  // - as a normal cleanup
1177  if (Scope.isNormalCleanup() &&
1178  (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
1180  needFlag = true;
1181  }
1182 
1183  // - as an EH cleanup
1184  if (Scope.isEHCleanup() &&
1185  (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
1186  Scope.setTestFlagInEHCleanup();
1187  needFlag = true;
1188  }
1189 
1190  // If it hasn't yet been used as either, we're done.
1191  if (!needFlag) return;
1192 
1193  Address var = Scope.getActiveFlag();
1194  if (!var.isValid()) {
1195  var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), CharUnits::One(),
1196  "cleanup.isactive");
1197  Scope.setActiveFlag(var);
1198 
1199  assert(dominatingIP && "no existing variable and no dominating IP!");
1200 
1201  // Initialize to true or false depending on whether it was
1202  // active up to this point.
1203  llvm::Constant *value = CGF.Builder.getInt1(kind == ForDeactivation);
1204 
1205  // If we're in a conditional block, ignore the dominating IP and
1206  // use the outermost conditional branch.
1207  if (CGF.isInConditionalBranch()) {
1208  CGF.setBeforeOutermostConditional(value, var);
1209  } else {
1210  createStoreInstBefore(value, var, dominatingIP);
1211  }
1212  }
1213 
1214  CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
1215 }
1216 
1217 /// Activate a cleanup that was created in an inactivated state.
1219  llvm::Instruction *dominatingIP) {
1220  assert(C != EHStack.stable_end() && "activating bottom of stack?");
1221  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1222  assert(!Scope.isActive() && "double activation");
1223 
1224  SetupCleanupBlockActivation(*this, C, ForActivation, dominatingIP);
1225 
1226  Scope.setActive(true);
1227 }
1228 
1229 /// Deactive a cleanup that was created in an active state.
1231  llvm::Instruction *dominatingIP) {
1232  assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
1233  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1234  assert(Scope.isActive() && "double deactivation");
1235 
1236  // If it's the top of the stack, just pop it.
1237  if (C == EHStack.stable_begin()) {
1238  // If it's a normal cleanup, we need to pretend that the
1239  // fallthrough is unreachable.
1240  CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1241  PopCleanupBlock();
1242  Builder.restoreIP(SavedIP);
1243  return;
1244  }
1245 
1246  // Otherwise, follow the general case.
1247  SetupCleanupBlockActivation(*this, C, ForDeactivation, dominatingIP);
1248 
1249  Scope.setActive(false);
1250 }
1251 
1253  if (!NormalCleanupDest)
1254  NormalCleanupDest =
1255  CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
1256  return Address(NormalCleanupDest, CharUnits::fromQuantity(4));
1257 }
1258 
1259 /// Emits all the code to cause the given temporary to be cleaned up.
1261  QualType TempType,
1262  Address Ptr) {
1263  pushDestroy(NormalAndEHCleanup, Ptr, TempType, destroyCXXObject,
1264  /*useEHCleanup*/ true);
1265 }
bool isAggregate() const
Definition: CGValue.h:54
const llvm::DataLayout & getDataLayout() const
void pushTerminate()
Push a terminate handler on the stack.
Definition: CGCleanup.cpp:259
static llvm::BasicBlock * CreateNormalEntry(CodeGenFunction &CGF, EHCleanupScope &Scope)
Definition: CGCleanup.cpp:501
EHScopeStack::stable_iterator getEnclosingEHScope() const
Definition: CGCleanup.h:138
void ActivateCleanupBlock(EHScopeStack::stable_iterator Cleanup, llvm::Instruction *DominatingIP)
ActivateCleanupBlock - Activates an initially-inactive cleanup.
Definition: CGCleanup.cpp:1218
A (possibly-)qualified type.
Definition: Type.h:614
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:313
static void destroyOptimisticNormalEntry(CodeGenFunction &CGF, EHCleanupScope &scope)
We don&#39;t need a normal entry block for the given cleanup.
Definition: CGCleanup.cpp:600
llvm::BasicBlock * getCachedEHDispatchBlock() const
Definition: CGCleanup.h:124
bool HaveInsertPoint() const
HaveInsertPoint - True if an insertion point is defined.
static stable_iterator stable_end()
Create a stable reference to the bottom of the EH stack.
Definition: EHScopeStack.h:384
tooling::Replacements cleanup(const FormatStyle &Style, StringRef Code, ArrayRef< tooling::Range > Ranges, StringRef FileName="<stdin>")
Clean up any erroneous/redundant code in the given Ranges in Code.
Definition: Format.cpp:1969
bool hasEHBranches() const
Definition: CGCleanup.h:132
static llvm::SwitchInst * TransitionToCleanupSwitch(CodeGenFunction &CGF, llvm::BasicBlock *Block)
Transitions the terminator of the given exit-block of a cleanup to be a cleanup switch.
Definition: CGCleanup.cpp:361
iterator find(stable_iterator save) const
Turn a stable reference to a scope depth into a unstable pointer to the EH stack. ...
Definition: CGCleanup.h:591
stable_iterator stable_begin() const
Create a stable reference to the top of the EH stack.
Definition: EHScopeStack.h:379
llvm::BasicBlock * getNormalBlock() const
Definition: CGCleanup.h:313
unsigned getNumFilters() const
Definition: CGCleanup.h:461
static bool needsSaving(llvm::Value *value)
Answer whether the given value needs extra work to be saved.
bool empty() const
Determines whether the exception-scopes stack is empty.
Definition: EHScopeStack.h:345
static void EmitCleanup(CodeGenFunction &CGF, EHScopeStack::Cleanup *Fn, EHScopeStack::Cleanup::Flags flags, Address ActiveFlag)
Definition: CGCleanup.cpp:551
llvm::Value * getPointer() const
Definition: Address.h:38
iterator begin() const
Returns an iterator pointing to the innermost EH scope.
Definition: CGCleanup.h:567
A protected scope for zero-cost EH handling.
Definition: CGCleanup.h:44
A scope which attempts to handle some, possibly all, types of exceptions.
Definition: CGCleanup.h:148
A jump destination is an abstract label, branching to which may require a jump out through normal cle...
bool addBranchThrough(llvm::BasicBlock *Block)
Add a branch-through to this cleanup scope.
Definition: CGCleanup.h:410
bool isObviouslyBranchWithoutCleanups(JumpDest Dest) const
isObviouslyBranchWithoutCleanups - Return true if a branch to the specified destination obviously has...
Definition: CGCleanup.cpp:1009
static size_t getSizeForCleanupSize(size_t Size)
Gets the size required for a lazy cleanup scope with the given cleanup-data requirements.
Definition: CGCleanup.h:280
An exceptions scope which calls std::terminate if any exception reaches it.
Definition: CGCleanup.h:480
CodeGenFunction - This class organizes the per-function state that is used while generating LLVM code...
ForActivation_t
Definition: CGCleanup.cpp:1150
bool shouldTestFlagInNormalCleanup() const
Definition: CGCleanup.h:336
Denotes a cleanup that should run when a scope is exited using exceptional control flow (a throw stat...
Definition: EHScopeStack.h:81
static const EHPersonality & get(CodeGenModule &CGM, const FunctionDecl *FD)
A metaprogramming class for ensuring that a value will dominate an arbitrary position in a function...
Definition: EHScopeStack.h:66
unsigned getNumBranchFixups() const
Definition: EHScopeStack.h:402
class EHCatchScope * pushCatch(unsigned NumHandlers)
Push a set of catch handlers on the stack.
Definition: CGCleanup.cpp:251
BranchFixup & getBranchFixup(unsigned I)
Definition: EHScopeStack.h:403
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
void setNormalBlock(llvm::BasicBlock *BB)
Definition: CGCleanup.h:314
CharUnits getAlignment() const
Return the alignment of this pointer.
Definition: Address.h:67
bool isComplex() const
Definition: CGValue.h:53
bool hasNormalCleanups() const
Determines whether there are any normal cleanups on the stack.
Definition: EHScopeStack.h:350
bool containsOnlyLifetimeMarkers(stable_iterator Old) const
Definition: CGCleanup.cpp:148
Scope - A scope is a transient data structure that is used while parsing the program.
Definition: Scope.h:39
void initFullExprCleanup()
Set up the last cleaup that was pushed as a conditional full-expression cleanup.
Definition: CGCleanup.cpp:284
A stack of scopes which respond to exceptions, including cleanups and catch blocks.
Definition: EHScopeStack.h:100
llvm::BasicBlock * createBasicBlock(const Twine &name="", llvm::Function *parent=nullptr, llvm::BasicBlock *before=nullptr)
createBasicBlock - Create an LLVM basic block.
Denotes a cleanup that should run when a scope is exited using normal control flow (falling off the e...
Definition: EHScopeStack.h:85
bool strictlyEncloses(stable_iterator I) const
Returns true if this scope strictly encloses I: that is, if it encloses I and is not I...
Definition: EHScopeStack.h:130
void popFilter()
Pops an exceptions filter off the stack.
Definition: CGCleanup.cpp:242
llvm::AllocaInst * CreateTempAlloca(llvm::Type *Ty, const Twine &Name="tmp", llvm::Value *ArraySize=nullptr)
CreateTempAlloca - This creates an alloca and inserts it into the entry block if ArraySize is nullptr...
Definition: CGExpr.cpp:91
static bool IsUsedAsEHCleanup(EHScopeStack &EHStack, EHScopeStack::stable_iterator cleanup)
Definition: CGCleanup.cpp:1129
static size_t getSizeForNumHandlers(unsigned N)
Definition: CGCleanup.h:178
Address getAggregateAddress() const
getAggregateAddr() - Return the Value* of the address of the aggregate.
Definition: CGValue.h:71
bool isValid() const
Definition: Address.h:36
static CharUnits One()
One - Construct a CharUnits quantity of one.
Definition: CharUnits.h:58
unsigned getFixupDepth() const
Definition: CGCleanup.h:347
std::pair< llvm::Value *, llvm::Value * > ComplexPairTy
static void createStoreInstBefore(llvm::Value *value, Address addr, llvm::Instruction *beforeInst)
Definition: CGCleanup.cpp:307
unsigned getNumBranchAfters() const
Return the number of unique branch-afters on this scope.
Definition: CGCleanup.h:381
RValue - This trivial value class is used to represent the result of an expression that is evaluated...
Definition: CGValue.h:39
static void ResolveAllBranchFixups(CodeGenFunction &CGF, llvm::SwitchInst *Switch, llvm::BasicBlock *CleanupEntry)
All the branch fixups on the EH stack have propagated out past the outermost normal cleanup; resolve ...
Definition: CGCleanup.cpp:323
llvm::BranchInst * InitialBranch
The initial branch of the fixup.
Definition: EHScopeStack.h:53
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
Address CreateDefaultAlignTempAlloca(llvm::Type *Ty, const Twine &Name="tmp")
CreateDefaultAlignedTempAlloca - This creates an alloca with the default ABI alignment of the given L...
Definition: CGExpr.cpp:104
EHScopeStack::stable_iterator getScopeDepth() const
void clearFixups()
Clears the branch-fixups list.
Definition: EHScopeStack.h:415
static Address invalid()
Definition: Address.h:35
stable_iterator getInnermostNormalCleanup() const
Returns the innermost normal cleanup on the stack, or stable_end() if there are no normal cleanups...
Definition: EHScopeStack.h:356
std::pair< llvm::Value *, llvm::Value * > getComplexVal() const
getComplexVal - Return the real/imag components of this complex value.
Definition: CGValue.h:66
size_t getCleanupSize() const
Definition: CGCleanup.h:352
llvm::AllocaInst * NormalCleanupDest
i32s containing the indexes of the cleanup destinations.
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
llvm::ConstantInt * getBranchAfterIndex(unsigned I) const
Definition: CGCleanup.h:390
void ResolveBranchFixups(llvm::BasicBlock *Target)
Definition: CGCleanup.cpp:381
void setActiveFlag(Address Var)
Definition: CGCleanup.h:328
stable_iterator stabilize(iterator it) const
Translates an iterator into a stable_iterator.
Definition: CGCleanup.h:598
bool encloses(stable_iterator I) const
Returns true if this scope encloses I.
Definition: EHScopeStack.h:124
size_t getAllocatedSize() const
Definition: CGCleanup.h:284
llvm::BasicBlock * OptimisticBranchBlock
The block containing the terminator which needs to be modified into a switch if this fixup is resolve...
Definition: EHScopeStack.h:41
void popCleanup()
Pops a cleanup scope off the stack. This is private to CGCleanup.cpp.
Definition: CGCleanup.cpp:209
The l-value was considered opaque, so the alignment was determined from a type.
void PopCleanupBlocks(EHScopeStack::stable_iterator OldCleanupStackSize, std::initializer_list< llvm::Value **> ValuesToReload={})
Takes the old cleanup stack size and emits the cleanup blocks that have been added.
Definition: CGCleanup.cpp:420
llvm::BasicBlock * Destination
The ultimate destination of the branch.
Definition: EHScopeStack.h:47
Kind
A saved depth on the scope stack.
Definition: EHScopeStack.h:107
Represents a C++ temporary.
Definition: ExprCXX.h:1103
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:1230
EHScopeStack::stable_iterator getEnclosingNormalCleanup() const
Definition: CGCleanup.h:348
void EmitCXXTemporary(const CXXTemporary *Temporary, QualType TempType, Address Ptr)
Emits all the code to cause the given temporary to be cleaned up.
Definition: CGCleanup.cpp:1260
An aligned address.
Definition: Address.h:25
unsigned DestinationIndex
The destination index value.
Definition: EHScopeStack.h:50
virtual void Emit(CodeGenFunction &CGF, Flags flags)=0
Emit the cleanup.
static size_t getSizeForNumFilters(unsigned numFilters)
Definition: CGCleanup.h:457
static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack, EHScopeStack::stable_iterator C)
Definition: CGCleanup.cpp:1110
static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit, llvm::BasicBlock *From, llvm::BasicBlock *To)
Definition: CGCleanup.cpp:576
llvm::Value * getScalarVal() const
getScalarVal() - Return the Value* of this scalar value.
Definition: CGValue.h:59
class EHFilterScope * pushFilter(unsigned NumFilters)
Push an exceptions filter on the stack.
Definition: CGCleanup.cpp:234
Dataflow Directional Tag Classes.
static RValue getComplex(llvm::Value *V1, llvm::Value *V2)
Definition: CGValue.h:93
void popNullFixups()
Pops lazily-removed fixups from the end of the list.
Definition: CGCleanup.cpp:270
bool shouldTestFlagInEHCleanup() const
Definition: CGCleanup.h:343
void addBranchAfter(llvm::ConstantInt *Index, llvm::BasicBlock *Block)
Add a branch-after to this cleanup scope.
Definition: CGCleanup.h:373
Address CreateStructGEP(Address Addr, unsigned Index, CharUnits Offset, const llvm::Twine &Name="")
Definition: CGBuilder.h:172
static llvm::BasicBlock * SimplifyCleanupEntry(CodeGenFunction &CGF, llvm::BasicBlock *Entry)
Attempts to reduce a cleanup&#39;s entry block to a fallthrough.
Definition: CGCleanup.cpp:517
bool isInConditionalBranch() const
isInConditionalBranch - Return true if we&#39;re currently emitting one branch or the other of a conditio...
llvm::LoadInst * CreateLoad(Address Addr, const llvm::Twine &Name="")
Definition: CGBuilder.h:70
Header for data within LifetimeExtendedCleanupStack.
llvm::StoreInst * CreateStore(llvm::Value *Val, Address Addr, bool IsVolatile=false)
Definition: CGBuilder.h:108
static void SetupCleanupBlockActivation(CodeGenFunction &CGF, EHScopeStack::stable_iterator C, ForActivation_t kind, llvm::Instruction *dominatingIP)
The given cleanup block is changing activation state.
Definition: CGCleanup.cpp:1160
stable_iterator getInnermostActiveNormalCleanup() const
Definition: CGCleanup.cpp:174
llvm::Value * getAggregatePointer() const
Definition: CGValue.h:76
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
EmitBlock - Emit the given block.
Definition: CGStmt.cpp:436
bool hasBranches() const
True if this cleanup scope has any branch-afters or branch-throughs.
Definition: CGCleanup.h:360
Address getActiveFlag() const
Definition: CGCleanup.h:325
unsigned kind
All of the diagnostics that can be emitted by the frontend.
Definition: DiagnosticIDs.h:61
llvm::BasicBlock * getBranchAfterBlock(unsigned I) const
Definition: CGCleanup.h:385
A cleanup scope which generates the cleanup blocks lazily.
Definition: CGCleanup.h:233
stable_iterator getInnermostEHScope() const
Definition: EHScopeStack.h:361
bool hasBranchThroughs() const
Determines if this cleanup scope has any branch throughs.
Definition: CGCleanup.h:415
An exceptions scope which filters exceptions thrown through it.
Definition: CGCleanup.h:438
static RValue get(llvm::Value *V)
Definition: CGValue.h:86
void EmitBranchThroughCleanup(JumpDest Dest)
EmitBranchThroughCleanup - Emit a branch from the current insert block through the normal cleanup han...
Definition: CGCleanup.cpp:1034
static RValue getAggregate(Address addr, bool isVolatile=false)
Definition: CGValue.h:107
Information for lazily generating a cleanup.
Definition: EHScopeStack.h:147
A non-stable pointer into the scope stack.
Definition: CGCleanup.h:503
void PopCleanupBlock(bool FallThroughIsBranchThrough=false)
PopCleanupBlock - Will pop the cleanup entry on the stack and process all branch fixups.
Definition: CGCleanup.cpp:640
bool isScalar() const
Definition: CGValue.h:52
static OMPLinearClause * Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation LParenLoc, OpenMPLinearClauseKind Modifier, SourceLocation ModifierLoc, SourceLocation ColonLoc, SourceLocation EndLoc, ArrayRef< Expr *> VL, ArrayRef< Expr *> PL, ArrayRef< Expr *> IL, Expr *Step, Expr *CalcStep, Stmt *PreInit, Expr *PostUpdate)
Creates clause with a list of variables VL and a linear step Step.