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
24using namespace clang;
25using namespace CodeGen;
26
27bool DominatingValue<RValue>::saved_type::needsSaving(RValue rv) {
28  if (rv.isScalar())
29    return DominatingLLVMValue::needsSaving(rv.getScalarVal());
30  if (rv.isAggregate())
31    return DominatingLLVMValue::needsSaving(rv.getAggregatePointer());
32  return true;
33}
34
35DominatingValue<RValue>::saved_type
36DominatingValue<RValue>::saved_type::save(CodeGenFunction &CGF, RValue rv) {
37  if (rv.isScalar()) {
38    llvm::Value *V = rv.getScalarVal();
39
40    // These automatically dominate and don't need to be saved.
41    if (!DominatingLLVMValue::needsSaving(V))
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()) {
52    CodeGenFunction::ComplexPairTy V = rv.getComplexVal();
53    llvm::Type *ComplexTy =
54      llvm::StructType::get(V.first->getType(), V.second->getType(),
55                            (void*) nullptr);
56    Address addr = CGF.CreateDefaultAlignTempAlloca(ComplexTy, "saved-complex");
57    CGF.Builder.CreateStore(V.first,
58                            CGF.Builder.CreateStructGEP(addr, 0, CharUnits()));
59    CharUnits offset = CharUnits::fromQuantity(
60               CGF.CGM.getDataLayout().getTypeAllocSize(V.first->getType()));
61    CGF.Builder.CreateStore(V.second,
62                            CGF.Builder.CreateStructGEP(addr, 1, offset));
63    return saved_type(addr.getPointer(), ComplexAddress);
64  }
65
66  assert(rv.isAggregate());
67  Address V = rv.getAggregateAddress(); // TODO: volatile?
68  if (!DominatingLLVMValue::needsSaving(V.getPointer()))
69    return saved_type(V.getPointer(), AggregateLiteral,
70                      V.getAlignment().getQuantity());
71
72  Address addr =
73    CGF.CreateTempAlloca(V.getType(), CGF.getPointerAlign(), "saved-rvalue");
74  CGF.Builder.CreateStore(V.getPointer(), addr);
75  return saved_type(addr.getPointer(), AggregateAddress,
76                    V.getAlignment().getQuantity());
77}
78
79/// Given a saved r-value produced by SaveRValue, perform the code
80/// necessary to restore it to usability at the current insertion
81/// point.
82RValue DominatingValue<RValue>::saved_type::restore(CodeGenFunction &CGF) {
83  auto getSavingAddress = [&](llvm::Value *value) {
84    auto alignment = cast<llvm::AllocaInst>(value)->getAlignment();
85    return Address(value, CharUnits::fromQuantity(alignment));
86  };
87  switch (K) {
88  case ScalarLiteral:
89    return RValue::get(Value);
90  case ScalarAddress:
91    return RValue::get(CGF.Builder.CreateLoad(getSavingAddress(Value)));
92  case AggregateLiteral:
93    return RValue::getAggregate(Address(Value, CharUnits::fromQuantity(Align)));
94  case AggregateAddress: {
95    auto addr = CGF.Builder.CreateLoad(getSavingAddress(Value));
96    return RValue::getAggregate(Address(addr, CharUnits::fromQuantity(Align)));
97  }
98  case ComplexAddress: {
99    Address address = getSavingAddress(Value);
100    llvm::Value *real = CGF.Builder.CreateLoad(
101                 CGF.Builder.CreateStructGEP(address, 0, CharUnits()));
102    CharUnits offset = CharUnits::fromQuantity(
103                 CGF.CGM.getDataLayout().getTypeAllocSize(real->getType()));
104    llvm::Value *imag = CGF.Builder.CreateLoad(
105                 CGF.Builder.CreateStructGEP(address, 1, offset));
106    return RValue::getComplex(real, imag);
107  }
108  }
109
110  llvm_unreachable("bad saved r-value kind");
111}
112
113/// Push an entry of the given size onto this protected-scope stack.
114char *EHScopeStack::allocate(size_t Size) {
115  Size = llvm::alignTo(Size, ScopeStackAlignment);
116  if (!StartOfBuffer) {
117    unsigned Capacity = 1024;
118    while (Capacity < Size) Capacity *= 2;
119    StartOfBuffer = new char[Capacity];
120    StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
121  } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
122    unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
123    unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
124
125    unsigned NewCapacity = CurrentCapacity;
126    do {
127      NewCapacity *= 2;
128    } while (NewCapacity < UsedCapacity + Size);
129
130    char *NewStartOfBuffer = new char[NewCapacity];
131    char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
132    char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
133    memcpy(NewStartOfData, StartOfData, UsedCapacity);
134    delete [] StartOfBuffer;
135    StartOfBuffer = NewStartOfBuffer;
136    EndOfBuffer = NewEndOfBuffer;
137    StartOfData = NewStartOfData;
138  }
139
140  assert(StartOfBuffer + Size <= StartOfData);
141  StartOfData -= Size;
142  return StartOfData;
143}
144
145void EHScopeStack::deallocate(size_t Size) {
146  StartOfData += llvm::alignTo(Size, ScopeStackAlignment);
147}
148
149bool EHScopeStack::containsOnlyLifetimeMarkers(
150    EHScopeStack::stable_iterator Old) const {
151  for (EHScopeStack::iterator it = begin(); stabilize(it) != Old; it++) {
152    EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*it);
153    if (!cleanup || !cleanup->isLifetimeMarker())
154      return false;
155  }
156
157  return true;
158}
159
160bool EHScopeStack::requiresLandingPad() const {
161  for (stable_iterator si = getInnermostEHScope(); si != stable_end(); ) {
162    // Skip lifetime markers.
163    if (auto *cleanup = dyn_cast<EHCleanupScope>(&*find(si)))
164      if (cleanup->isLifetimeMarker()) {
165        si = cleanup->getEnclosingEHScope();
166        continue;
167      }
168    return true;
169  }
170
171  return false;
172}
173
174EHScopeStack::stable_iterator
175EHScopeStack::getInnermostActiveNormalCleanup() const {
176  for (stable_iterator si = getInnermostNormalCleanup(), se = stable_end();
177         si != se; ) {
178    EHCleanupScope &cleanup = cast<EHCleanupScope>(*find(si));
179    if (cleanup.isActive()) return si;
180    si = cleanup.getEnclosingNormalCleanup();
181  }
182  return stable_end();
183}
184
185
186void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
187  char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
188  bool IsNormalCleanup = Kind & NormalCleanup;
189  bool IsEHCleanup = Kind & EHCleanup;
190  bool IsActive = !(Kind & InactiveCleanup);
191  bool IsLifetimeMarker = Kind & LifetimeMarker;
192  EHCleanupScope *Scope =
193    new (Buffer) EHCleanupScope(IsNormalCleanup,
194                                IsEHCleanup,
195                                IsActive,
196                                Size,
197                                BranchFixups.size(),
198                                InnermostNormalCleanup,
199                                InnermostEHScope);
200  if (IsNormalCleanup)
201    InnermostNormalCleanup = stable_begin();
202  if (IsEHCleanup)
203    InnermostEHScope = stable_begin();
204  if (IsLifetimeMarker)
205    Scope->setLifetimeMarker();
206
207  return Scope->getCleanupBuffer();
208}
209
210void EHScopeStack::popCleanup() {
211  assert(!empty() && "popping exception stack when not empty");
212
213  assert(isa<EHCleanupScope>(*begin()));
214  EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
215  InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
216  InnermostEHScope = Cleanup.getEnclosingEHScope();
217  deallocate(Cleanup.getAllocatedSize());
218
219  // Destroy the cleanup.
220  Cleanup.Destroy();
221
222  // Check whether we can shrink the branch-fixups stack.
223  if (!BranchFixups.empty()) {
224    // If we no longer have any normal cleanups, all the fixups are
225    // complete.
226    if (!hasNormalCleanups())
227      BranchFixups.clear();
228
229    // Otherwise we can still trim out unnecessary nulls.
230    else
231      popNullFixups();
232  }
233}
234
235EHFilterScope *EHScopeStack::pushFilter(unsigned numFilters) {
236  assert(getInnermostEHScope() == stable_end());
237  char *buffer = allocate(EHFilterScope::getSizeForNumFilters(numFilters));
238  EHFilterScope *filter = new (buffer) EHFilterScope(numFilters);
239  InnermostEHScope = stable_begin();
240  return filter;
241}
242
243void EHScopeStack::popFilter() {
244  assert(!empty() && "popping exception stack when not empty");
245
246  EHFilterScope &filter = cast<EHFilterScope>(*begin());
247  deallocate(EHFilterScope::getSizeForNumFilters(filter.getNumFilters()));
248
249  InnermostEHScope = filter.getEnclosingEHScope();
250}
251
252EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) {
253  char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers));
254  EHCatchScope *scope =
255    new (buffer) EHCatchScope(numHandlers, InnermostEHScope);
256  InnermostEHScope = stable_begin();
257  return scope;
258}
259
260void EHScopeStack::pushTerminate() {
261  char *Buffer = allocate(EHTerminateScope::getSize());
262  new (Buffer) EHTerminateScope(InnermostEHScope);
263  InnermostEHScope = stable_begin();
264}
265
266/// Remove any 'null' fixups on the stack.  However, we can't pop more
267/// fixups than the fixup depth on the innermost normal cleanup, or
268/// else fixups that we try to add to that cleanup will end up in the
269/// wrong place.  We *could* try to shrink fixup depths, but that's
270/// actually a lot of work for little benefit.
271void EHScopeStack::popNullFixups() {
272  // We expect this to only be called when there's still an innermost
273  // normal cleanup;  otherwise there really shouldn't be any fixups.
274  assert(hasNormalCleanups());
275
276  EHScopeStack::iterator it = find(InnermostNormalCleanup);
277  unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
278  assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
279
280  while (BranchFixups.size() > MinSize &&
281         BranchFixups.back().Destination == nullptr)
282    BranchFixups.pop_back();
283}
284
285void CodeGenFunction::initFullExprCleanup() {
286  // Create a variable to decide whether the cleanup needs to be run.
287  Address active = CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(),
288                                    "cleanup.cond");
289
290  // Initialize it to false at a site that's guaranteed to be run
291  // before each evaluation.
292  setBeforeOutermostConditional(Builder.getFalse(), active);
293
294  // Initialize it to true at the current location.
295  Builder.CreateStore(Builder.getTrue(), active);
296
297  // Set that as the active flag in the cleanup.
298  EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
299  assert(!cleanup.hasActiveFlag() && "cleanup already has active flag?");
300  cleanup.setActiveFlag(active);
301
302  if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
303  if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
304}
305
306void EHScopeStack::Cleanup::anchor() {}
307
308static void createStoreInstBefore(llvm::Value *value, Address addr,
309                                  llvm::Instruction *beforeInst) {
310  auto store = new llvm::StoreInst(value, addr.getPointer(), beforeInst);
311  store->setAlignment(addr.getAlignment().getQuantity());
312}
313
314static llvm::LoadInst *createLoadInstBefore(Address addr, const Twine &name,
315                                            llvm::Instruction *beforeInst) {
316  auto load = new llvm::LoadInst(addr.getPointer(), name, beforeInst);
317  load->setAlignment(addr.getAlignment().getQuantity());
318  return load;
319}
320
321/// All the branch fixups on the EH stack have propagated out past the
322/// outermost normal cleanup; resolve them all by adding cases to the
323/// given switch instruction.
324static void ResolveAllBranchFixups(CodeGenFunction &CGF,
325                                   llvm::SwitchInst *Switch,
326                                   llvm::BasicBlock *CleanupEntry) {
327  llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
328
329  for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
330    // Skip this fixup if its destination isn't set.
331    BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
332    if (Fixup.Destination == nullptr) continue;
333
334    // If there isn't an OptimisticBranchBlock, then InitialBranch is
335    // still pointing directly to its destination; forward it to the
336    // appropriate cleanup entry.  This is required in the specific
337    // case of
338    //   { std::string s; goto lbl; }
339    //   lbl:
340    // i.e. where there's an unresolved fixup inside a single cleanup
341    // entry which we're currently popping.
342    if (Fixup.OptimisticBranchBlock == nullptr) {
343      createStoreInstBefore(CGF.Builder.getInt32(Fixup.DestinationIndex),
344                            CGF.getNormalCleanupDestSlot(),
345                            Fixup.InitialBranch);
346      Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
347    }
348
349    // Don't add this case to the switch statement twice.
350    if (!CasesAdded.insert(Fixup.Destination).second)
351      continue;
352
353    Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
354                    Fixup.Destination);
355  }
356
357  CGF.EHStack.clearFixups();
358}
359
360/// Transitions the terminator of the given exit-block of a cleanup to
361/// be a cleanup switch.
362static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
363                                                   llvm::BasicBlock *Block) {
364  // If it's a branch, turn it into a switch whose default
365  // destination is its original target.
366  llvm::TerminatorInst *Term = Block->getTerminator();
367  assert(Term && "can't transition block without terminator");
368
369  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
370    assert(Br->isUnconditional());
371    auto Load = createLoadInstBefore(CGF.getNormalCleanupDestSlot(),
372                                     "cleanup.dest", Term);
373    llvm::SwitchInst *Switch =
374      llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
375    Br->eraseFromParent();
376    return Switch;
377  } else {
378    return cast<llvm::SwitchInst>(Term);
379  }
380}
381
382void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
383  assert(Block && "resolving a null target block");
384  if (!EHStack.getNumBranchFixups()) return;
385
386  assert(EHStack.hasNormalCleanups() &&
387         "branch fixups exist with no normal cleanups on stack");
388
389  llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
390  bool ResolvedAny = false;
391
392  for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
393    // Skip this fixup if its destination doesn't match.
394    BranchFixup &Fixup = EHStack.getBranchFixup(I);
395    if (Fixup.Destination != Block) continue;
396
397    Fixup.Destination = nullptr;
398    ResolvedAny = true;
399
400    // If it doesn't have an optimistic branch block, LatestBranch is
401    // already pointing to the right place.
402    llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
403    if (!BranchBB)
404      continue;
405
406    // Don't process the same optimistic branch block twice.
407    if (!ModifiedOptimisticBlocks.insert(BranchBB).second)
408      continue;
409
410    llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
411
412    // Add a case to the switch.
413    Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
414  }
415
416  if (ResolvedAny)
417    EHStack.popNullFixups();
418}
419
420/// Pops cleanup blocks until the given savepoint is reached.
421void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) {
422  assert(Old.isValid());
423
424  while (EHStack.stable_begin() != Old) {
425    EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
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 =
431      Old.strictlyEncloses(Scope.getEnclosingNormalCleanup());
432
433    PopCleanupBlock(FallThroughIsBranchThrough);
434  }
435}
436
437/// Pops cleanup blocks until the given savepoint is reached, then add the
438/// cleanups from the given savepoint in the lifetime-extended cleanups stack.
439void
440CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old,
441                                  size_t OldLifetimeExtendedSize) {
442  PopCleanupBlocks(Old);
443
444  // Move our deferred cleanups onto the EH stack.
445  for (size_t I = OldLifetimeExtendedSize,
446              E = LifetimeExtendedCleanupStack.size(); I != E; /**/) {
447    // Alignment should be guaranteed by the vptrs in the individual cleanups.
448    assert((I % llvm::alignOf<LifetimeExtendedCleanupHeader>() == 0) &&
449           "misaligned cleanup stack entry");
450
451    LifetimeExtendedCleanupHeader &Header =
452        reinterpret_cast<LifetimeExtendedCleanupHeader&>(
453            LifetimeExtendedCleanupStack[I]);
454    I += sizeof(Header);
455
456    EHStack.pushCopyOfCleanup(Header.getKind(),
457                              &LifetimeExtendedCleanupStack[I],
458                              Header.getSize());
459    I += Header.getSize();
460  }
461  LifetimeExtendedCleanupStack.resize(OldLifetimeExtendedSize);
462}
463
464static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
465                                           EHCleanupScope &Scope) {
466  assert(Scope.isNormalCleanup());
467  llvm::BasicBlock *Entry = Scope.getNormalBlock();
468  if (!Entry) {
469    Entry = CGF.createBasicBlock("cleanup");
470    Scope.setNormalBlock(Entry);
471  }
472  return Entry;
473}
474
475/// Attempts to reduce a cleanup's entry block to a fallthrough.  This
476/// is basically llvm::MergeBlockIntoPredecessor, except
477/// simplified/optimized for the tighter constraints on cleanup blocks.
478///
479/// Returns the new block, whatever it is.
480static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
481                                              llvm::BasicBlock *Entry) {
482  llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
483  if (!Pred) return Entry;
484
485  llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
486  if (!Br || Br->isConditional()) return Entry;
487  assert(Br->getSuccessor(0) == Entry);
488
489  // If we were previously inserting at the end of the cleanup entry
490  // block, we'll need to continue inserting at the end of the
491  // predecessor.
492  bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
493  assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
494
495  // Kill the branch.
496  Br->eraseFromParent();
497
498  // Replace all uses of the entry with the predecessor, in case there
499  // are phis in the cleanup.
500  Entry->replaceAllUsesWith(Pred);
501
502  // Merge the blocks.
503  Pred->getInstList().splice(Pred->end(), Entry->getInstList());
504
505  // Kill the entry block.
506  Entry->eraseFromParent();
507
508  if (WasInsertBlock)
509    CGF.Builder.SetInsertPoint(Pred);
510
511  return Pred;
512}
513
514static void EmitCleanup(CodeGenFunction &CGF,
515                        EHScopeStack::Cleanup *Fn,
516                        EHScopeStack::Cleanup::Flags flags,
517                        Address ActiveFlag) {
518  // If there's an active flag, load it and skip the cleanup if it's
519  // false.
520  llvm::BasicBlock *ContBB = nullptr;
521  if (ActiveFlag.isValid()) {
522    ContBB = CGF.createBasicBlock("cleanup.done");
523    llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
524    llvm::Value *IsActive
525      = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
526    CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
527    CGF.EmitBlock(CleanupBB);
528  }
529
530  // Ask the cleanup to emit itself.
531  Fn->Emit(CGF, flags);
532  assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
533
534  // Emit the continuation block if there was an active flag.
535  if (ActiveFlag.isValid())
536    CGF.EmitBlock(ContBB);
537}
538
539static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
540                                          llvm::BasicBlock *From,
541                                          llvm::BasicBlock *To) {
542  // Exit is the exit block of a cleanup, so it always terminates in
543  // an unconditional branch or a switch.
544  llvm::TerminatorInst *Term = Exit->getTerminator();
545
546  if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
547    assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
548    Br->setSuccessor(0, To);
549  } else {
550    llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
551    for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
552      if (Switch->getSuccessor(I) == From)
553        Switch->setSuccessor(I, To);
554  }
555}
556
557/// We don't need a normal entry block for the given cleanup.
558/// Optimistic fixup branches can cause these blocks to come into
559/// existence anyway;  if so, destroy it.
560///
561/// The validity of this transformation is very much specific to the
562/// exact ways in which we form branches to cleanup entries.
563static void destroyOptimisticNormalEntry(CodeGenFunction &CGF,
564                                         EHCleanupScope &scope) {
565  llvm::BasicBlock *entry = scope.getNormalBlock();
566  if (!entry) return;
567
568  // Replace all the uses with unreachable.
569  llvm::BasicBlock *unreachableBB = CGF.getUnreachableBlock();
570  for (llvm::BasicBlock::use_iterator
571         i = entry->use_begin(), e = entry->use_end(); i != e; ) {
572    llvm::Use &use = *i;
573    ++i;
574
575    use.set(unreachableBB);
576
577    // The only uses should be fixup switches.
578    llvm::SwitchInst *si = cast<llvm::SwitchInst>(use.getUser());
579    if (si->getNumCases() == 1 && si->getDefaultDest() == unreachableBB) {
580      // Replace the switch with a branch.
581      llvm::BranchInst::Create(si->case_begin().getCaseSuccessor(), si);
582
583      // The switch operand is a load from the cleanup-dest alloca.
584      llvm::LoadInst *condition = cast<llvm::LoadInst>(si->getCondition());
585
586      // Destroy the switch.
587      si->eraseFromParent();
588
589      // Destroy the load.
590      assert(condition->getOperand(0) == CGF.NormalCleanupDest);
591      assert(condition->use_empty());
592      condition->eraseFromParent();
593    }
594  }
595
596  assert(entry->use_empty());
597  delete entry;
598}
599
600/// Pops a cleanup block.  If the block includes a normal cleanup, the
601/// current insertion point is threaded through the cleanup, as are
602/// any branch fixups on the cleanup.
603void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
604  assert(!EHStack.empty() && "cleanup stack is empty!");
605  assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
606  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
607  assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
608
609  // Remember activation information.
610  bool IsActive = Scope.isActive();
611  Address NormalActiveFlag =
612    Scope.shouldTestFlagInNormalCleanup() ? Scope.getActiveFlag()
613                                          : Address::invalid();
614  Address EHActiveFlag =
615    Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag()
616                                      : Address::invalid();
617
618  // Check whether we need an EH cleanup.  This is only true if we've
619  // generated a lazy EH cleanup block.
620  llvm::BasicBlock *EHEntry = Scope.getCachedEHDispatchBlock();
621  assert(Scope.hasEHBranches() == (EHEntry != nullptr));
622  bool RequiresEHCleanup = (EHEntry != nullptr);
623  EHScopeStack::stable_iterator EHParent = Scope.getEnclosingEHScope();
624
625  // Check the three conditions which might require a normal cleanup:
626
627  // - whether there are branch fix-ups through this cleanup
628  unsigned FixupDepth = Scope.getFixupDepth();
629  bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
630
631  // - whether there are branch-throughs or branch-afters
632  bool HasExistingBranches = Scope.hasBranches();
633
634  // - whether there's a fallthrough
635  llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
636  bool HasFallthrough = (FallthroughSource != nullptr && IsActive);
637
638  // Branch-through fall-throughs leave the insertion point set to the
639  // end of the last cleanup, which points to the current scope.  The
640  // rest of IR gen doesn't need to worry about this; it only happens
641  // during the execution of PopCleanupBlocks().
642  bool HasPrebranchedFallthrough =
643    (FallthroughSource && FallthroughSource->getTerminator());
644
645  // If this is a normal cleanup, then having a prebranched
646  // fallthrough implies that the fallthrough source unconditionally
647  // jumps here.
648  assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
649         (Scope.getNormalBlock() &&
650          FallthroughSource->getTerminator()->getSuccessor(0)
651            == Scope.getNormalBlock()));
652
653  bool RequiresNormalCleanup = false;
654  if (Scope.isNormalCleanup() &&
655      (HasFixups || HasExistingBranches || HasFallthrough)) {
656    RequiresNormalCleanup = true;
657  }
658
659  // If we have a prebranched fallthrough into an inactive normal
660  // cleanup, rewrite it so that it leads to the appropriate place.
661  if (Scope.isNormalCleanup() && HasPrebranchedFallthrough && !IsActive) {
662    llvm::BasicBlock *prebranchDest;
663
664    // If the prebranch is semantically branching through the next
665    // cleanup, just forward it to the next block, leaving the
666    // insertion point in the prebranched block.
667    if (FallthroughIsBranchThrough) {
668      EHScope &enclosing = *EHStack.find(Scope.getEnclosingNormalCleanup());
669      prebranchDest = CreateNormalEntry(*this, cast<EHCleanupScope>(enclosing));
670
671    // Otherwise, we need to make a new block.  If the normal cleanup
672    // isn't being used at all, we could actually reuse the normal
673    // entry block, but this is simpler, and it avoids conflicts with
674    // dead optimistic fixup branches.
675    } else {
676      prebranchDest = createBasicBlock("forwarded-prebranch");
677      EmitBlock(prebranchDest);
678    }
679
680    llvm::BasicBlock *normalEntry = Scope.getNormalBlock();
681    assert(normalEntry && !normalEntry->use_empty());
682
683    ForwardPrebranchedFallthrough(FallthroughSource,
684                                  normalEntry, prebranchDest);
685  }
686
687  // If we don't need the cleanup at all, we're done.
688  if (!RequiresNormalCleanup && !RequiresEHCleanup) {
689    destroyOptimisticNormalEntry(*this, Scope);
690    EHStack.popCleanup(); // safe because there are no fixups
691    assert(EHStack.getNumBranchFixups() == 0 ||
692           EHStack.hasNormalCleanups());
693    return;
694  }
695
696  // Copy the cleanup emission data out.  This uses either a stack
697  // array or malloc'd memory, depending on the size, which is
698  // behavior that SmallVector would provide, if we could use it
699  // here. Unfortunately, if you ask for a SmallVector<char>, the
700  // alignment isn't sufficient.
701  auto *CleanupSource = reinterpret_cast<char *>(Scope.getCleanupBuffer());
702  llvm::AlignedCharArray<EHScopeStack::ScopeStackAlignment, 8 * sizeof(void *)> CleanupBufferStack;
703  std::unique_ptr<char[]> CleanupBufferHeap;
704  size_t CleanupSize = Scope.getCleanupSize();
705  EHScopeStack::Cleanup *Fn;
706
707  if (CleanupSize <= sizeof(CleanupBufferStack)) {
708    memcpy(CleanupBufferStack.buffer, CleanupSource, CleanupSize);
709    Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferStack.buffer);
710  } else {
711    CleanupBufferHeap.reset(new char[CleanupSize]);
712    memcpy(CleanupBufferHeap.get(), CleanupSource, CleanupSize);
713    Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferHeap.get());
714  }
715
716  EHScopeStack::Cleanup::Flags cleanupFlags;
717  if (Scope.isNormalCleanup())
718    cleanupFlags.setIsNormalCleanupKind();
719  if (Scope.isEHCleanup())
720    cleanupFlags.setIsEHCleanupKind();
721
722  if (!RequiresNormalCleanup) {
723    destroyOptimisticNormalEntry(*this, Scope);
724    EHStack.popCleanup();
725  } else {
726    // If we have a fallthrough and no other need for the cleanup,
727    // emit it directly.
728    if (HasFallthrough && !HasPrebranchedFallthrough &&
729        !HasFixups && !HasExistingBranches) {
730
731      destroyOptimisticNormalEntry(*this, Scope);
732      EHStack.popCleanup();
733
734      EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
735
736    // Otherwise, the best approach is to thread everything through
737    // the cleanup block and then try to clean up after ourselves.
738    } else {
739      // Force the entry block to exist.
740      llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
741
742      // I.  Set up the fallthrough edge in.
743
744      CGBuilderTy::InsertPoint savedInactiveFallthroughIP;
745
746      // If there's a fallthrough, we need to store the cleanup
747      // destination index.  For fall-throughs this is always zero.
748      if (HasFallthrough) {
749        if (!HasPrebranchedFallthrough)
750          Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
751
752      // Otherwise, save and clear the IP if we don't have fallthrough
753      // because the cleanup is inactive.
754      } else if (FallthroughSource) {
755        assert(!IsActive && "source without fallthrough for active cleanup");
756        savedInactiveFallthroughIP = Builder.saveAndClearIP();
757      }
758
759      // II.  Emit the entry block.  This implicitly branches to it if
760      // we have fallthrough.  All the fixups and existing branches
761      // should already be branched to it.
762      EmitBlock(NormalEntry);
763
764      // III.  Figure out where we're going and build the cleanup
765      // epilogue.
766
767      bool HasEnclosingCleanups =
768        (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
769
770      // Compute the branch-through dest if we need it:
771      //   - if there are branch-throughs threaded through the scope
772      //   - if fall-through is a branch-through
773      //   - if there are fixups that will be optimistically forwarded
774      //     to the enclosing cleanup
775      llvm::BasicBlock *BranchThroughDest = nullptr;
776      if (Scope.hasBranchThroughs() ||
777          (FallthroughSource && FallthroughIsBranchThrough) ||
778          (HasFixups && HasEnclosingCleanups)) {
779        assert(HasEnclosingCleanups);
780        EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
781        BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
782      }
783
784      llvm::BasicBlock *FallthroughDest = nullptr;
785      SmallVector<llvm::Instruction*, 2> InstsToAppend;
786
787      // If there's exactly one branch-after and no other threads,
788      // we can route it without a switch.
789      if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
790          Scope.getNumBranchAfters() == 1) {
791        assert(!BranchThroughDest || !IsActive);
792
793        // Clean up the possibly dead store to the cleanup dest slot.
794        llvm::Instruction *NormalCleanupDestSlot =
795            cast<llvm::Instruction>(getNormalCleanupDestSlot().getPointer());
796        if (NormalCleanupDestSlot->hasOneUse()) {
797          NormalCleanupDestSlot->user_back()->eraseFromParent();
798          NormalCleanupDestSlot->eraseFromParent();
799          NormalCleanupDest = nullptr;
800        }
801
802        llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
803        InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
804
805      // Build a switch-out if we need it:
806      //   - if there are branch-afters threaded through the scope
807      //   - if fall-through is a branch-after
808      //   - if there are fixups that have nowhere left to go and
809      //     so must be immediately resolved
810      } else if (Scope.getNumBranchAfters() ||
811                 (HasFallthrough && !FallthroughIsBranchThrough) ||
812                 (HasFixups && !HasEnclosingCleanups)) {
813
814        llvm::BasicBlock *Default =
815          (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
816
817        // TODO: base this on the number of branch-afters and fixups
818        const unsigned SwitchCapacity = 10;
819
820        llvm::LoadInst *Load =
821          createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
822                               nullptr);
823        llvm::SwitchInst *Switch =
824          llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
825
826        InstsToAppend.push_back(Load);
827        InstsToAppend.push_back(Switch);
828
829        // Branch-after fallthrough.
830        if (FallthroughSource && !FallthroughIsBranchThrough) {
831          FallthroughDest = createBasicBlock("cleanup.cont");
832          if (HasFallthrough)
833            Switch->addCase(Builder.getInt32(0), FallthroughDest);
834        }
835
836        for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
837          Switch->addCase(Scope.getBranchAfterIndex(I),
838                          Scope.getBranchAfterBlock(I));
839        }
840
841        // If there aren't any enclosing cleanups, we can resolve all
842        // the fixups now.
843        if (HasFixups && !HasEnclosingCleanups)
844          ResolveAllBranchFixups(*this, Switch, NormalEntry);
845      } else {
846        // We should always have a branch-through destination in this case.
847        assert(BranchThroughDest);
848        InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
849      }
850
851      // IV.  Pop the cleanup and emit it.
852      EHStack.popCleanup();
853      assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
854
855      EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
856
857      // Append the prepared cleanup prologue from above.
858      llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
859      for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
860        NormalExit->getInstList().push_back(InstsToAppend[I]);
861
862      // Optimistically hope that any fixups will continue falling through.
863      for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
864           I < E; ++I) {
865        BranchFixup &Fixup = EHStack.getBranchFixup(I);
866        if (!Fixup.Destination) continue;
867        if (!Fixup.OptimisticBranchBlock) {
868          createStoreInstBefore(Builder.getInt32(Fixup.DestinationIndex),
869                                getNormalCleanupDestSlot(),
870                                Fixup.InitialBranch);
871          Fixup.InitialBranch->setSuccessor(0, NormalEntry);
872        }
873        Fixup.OptimisticBranchBlock = NormalExit;
874      }
875
876      // V.  Set up the fallthrough edge out.
877
878      // Case 1: a fallthrough source exists but doesn't branch to the
879      // cleanup because the cleanup is inactive.
880      if (!HasFallthrough && FallthroughSource) {
881        // Prebranched fallthrough was forwarded earlier.
882        // Non-prebranched fallthrough doesn't need to be forwarded.
883        // Either way, all we need to do is restore the IP we cleared before.
884        assert(!IsActive);
885        Builder.restoreIP(savedInactiveFallthroughIP);
886
887      // Case 2: a fallthrough source exists and should branch to the
888      // cleanup, but we're not supposed to branch through to the next
889      // cleanup.
890      } else if (HasFallthrough && FallthroughDest) {
891        assert(!FallthroughIsBranchThrough);
892        EmitBlock(FallthroughDest);
893
894      // Case 3: a fallthrough source exists and should branch to the
895      // cleanup and then through to the next.
896      } else if (HasFallthrough) {
897        // Everything is already set up for this.
898
899      // Case 4: no fallthrough source exists.
900      } else {
901        Builder.ClearInsertionPoint();
902      }
903
904      // VI.  Assorted cleaning.
905
906      // Check whether we can merge NormalEntry into a single predecessor.
907      // This might invalidate (non-IR) pointers to NormalEntry.
908      llvm::BasicBlock *NewNormalEntry =
909        SimplifyCleanupEntry(*this, NormalEntry);
910
911      // If it did invalidate those pointers, and NormalEntry was the same
912      // as NormalExit, go back and patch up the fixups.
913      if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
914        for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
915               I < E; ++I)
916          EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
917    }
918  }
919
920  assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
921
922  // Emit the EH cleanup if required.
923  if (RequiresEHCleanup) {
924    CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
925
926    EmitBlock(EHEntry);
927
928    llvm::BasicBlock *NextAction = getEHDispatchBlock(EHParent);
929
930    // Push a terminate scope or cleanupendpad scope around the potentially
931    // throwing cleanups. For funclet EH personalities, the cleanupendpad models
932    // program termination when cleanups throw.
933    bool PushedTerminate = false;
934    SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
935        CurrentFuncletPad);
936    llvm::CleanupPadInst *CPI = nullptr;
937    if (!EHPersonality::get(*this).usesFuncletPads()) {
938      EHStack.pushTerminate();
939      PushedTerminate = true;
940    } else {
941      llvm::Value *ParentPad = CurrentFuncletPad;
942      if (!ParentPad)
943        ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
944      CurrentFuncletPad = CPI = Builder.CreateCleanupPad(ParentPad);
945    }
946
947    // We only actually emit the cleanup code if the cleanup is either
948    // active or was used before it was deactivated.
949    if (EHActiveFlag.isValid() || IsActive) {
950      cleanupFlags.setIsForEHCleanup();
951      EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
952    }
953
954    if (CPI)
955      Builder.CreateCleanupRet(CPI, NextAction);
956    else
957      Builder.CreateBr(NextAction);
958
959    // Leave the terminate scope.
960    if (PushedTerminate)
961      EHStack.popTerminate();
962
963    Builder.restoreIP(SavedIP);
964
965    SimplifyCleanupEntry(*this, EHEntry);
966  }
967}
968
969/// isObviouslyBranchWithoutCleanups - Return true if a branch to the
970/// specified destination obviously has no cleanups to run.  'false' is always
971/// a conservatively correct answer for this method.
972bool CodeGenFunction::isObviouslyBranchWithoutCleanups(JumpDest Dest) const {
973  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
974         && "stale jump destination");
975
976  // Calculate the innermost active normal cleanup.
977  EHScopeStack::stable_iterator TopCleanup =
978    EHStack.getInnermostActiveNormalCleanup();
979
980  // If we're not in an active normal cleanup scope, or if the
981  // destination scope is within the innermost active normal cleanup
982  // scope, we don't need to worry about fixups.
983  if (TopCleanup == EHStack.stable_end() ||
984      TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid
985    return true;
986
987  // Otherwise, we might need some cleanups.
988  return false;
989}
990
991
992/// Terminate the current block by emitting a branch which might leave
993/// the current cleanup-protected scope.  The target scope may not yet
994/// be known, in which case this will require a fixup.
995///
996/// As a side-effect, this method clears the insertion point.
997void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) {
998  assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
999         && "stale jump destination");
1000
1001  if (!HaveInsertPoint())
1002    return;
1003
1004  // Create the branch.
1005  llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
1006
1007  // Calculate the innermost active normal cleanup.
1008  EHScopeStack::stable_iterator
1009    TopCleanup = EHStack.getInnermostActiveNormalCleanup();
1010
1011  // If we're not in an active normal cleanup scope, or if the
1012  // destination scope is within the innermost active normal cleanup
1013  // scope, we don't need to worry about fixups.
1014  if (TopCleanup == EHStack.stable_end() ||
1015      TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
1016    Builder.ClearInsertionPoint();
1017    return;
1018  }
1019
1020  // If we can't resolve the destination cleanup scope, just add this
1021  // to the current cleanup scope as a branch fixup.
1022  if (!Dest.getScopeDepth().isValid()) {
1023    BranchFixup &Fixup = EHStack.addBranchFixup();
1024    Fixup.Destination = Dest.getBlock();
1025    Fixup.DestinationIndex = Dest.getDestIndex();
1026    Fixup.InitialBranch = BI;
1027    Fixup.OptimisticBranchBlock = nullptr;
1028
1029    Builder.ClearInsertionPoint();
1030    return;
1031  }
1032
1033  // Otherwise, thread through all the normal cleanups in scope.
1034
1035  // Store the index at the start.
1036  llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
1037  createStoreInstBefore(Index, getNormalCleanupDestSlot(), BI);
1038
1039  // Adjust BI to point to the first cleanup block.
1040  {
1041    EHCleanupScope &Scope =
1042      cast<EHCleanupScope>(*EHStack.find(TopCleanup));
1043    BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
1044  }
1045
1046  // Add this destination to all the scopes involved.
1047  EHScopeStack::stable_iterator I = TopCleanup;
1048  EHScopeStack::stable_iterator E = Dest.getScopeDepth();
1049  if (E.strictlyEncloses(I)) {
1050    while (true) {
1051      EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
1052      assert(Scope.isNormalCleanup());
1053      I = Scope.getEnclosingNormalCleanup();
1054
1055      // If this is the last cleanup we're propagating through, tell it
1056      // that there's a resolved jump moving through it.
1057      if (!E.strictlyEncloses(I)) {
1058        Scope.addBranchAfter(Index, Dest.getBlock());
1059        break;
1060      }
1061
1062      // Otherwise, tell the scope that there's a jump propoagating
1063      // through it.  If this isn't new information, all the rest of
1064      // the work has been done before.
1065      if (!Scope.addBranchThrough(Dest.getBlock()))
1066        break;
1067    }
1068  }
1069
1070  Builder.ClearInsertionPoint();
1071}
1072
1073static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack,
1074                                  EHScopeStack::stable_iterator C) {
1075  // If we needed a normal block for any reason, that counts.
1076  if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
1077    return true;
1078
1079  // Check whether any enclosed cleanups were needed.
1080  for (EHScopeStack::stable_iterator
1081         I = EHStack.getInnermostNormalCleanup();
1082         I != C; ) {
1083    assert(C.strictlyEncloses(I));
1084    EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
1085    if (S.getNormalBlock()) return true;
1086    I = S.getEnclosingNormalCleanup();
1087  }
1088
1089  return false;
1090}
1091
1092static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
1093                              EHScopeStack::stable_iterator cleanup) {
1094  // If we needed an EH block for any reason, that counts.
1095  if (EHStack.find(cleanup)->hasEHBranches())
1096    return true;
1097
1098  // Check whether any enclosed cleanups were needed.
1099  for (EHScopeStack::stable_iterator
1100         i = EHStack.getInnermostEHScope(); i != cleanup; ) {
1101    assert(cleanup.strictlyEncloses(i));
1102
1103    EHScope &scope = *EHStack.find(i);
1104    if (scope.hasEHBranches())
1105      return true;
1106
1107    i = scope.getEnclosingEHScope();
1108  }
1109
1110  return false;
1111}
1112
1113enum ForActivation_t {
1114  ForActivation,
1115  ForDeactivation
1116};
1117
1118/// The given cleanup block is changing activation state.  Configure a
1119/// cleanup variable if necessary.
1120///
1121/// It would be good if we had some way of determining if there were
1122/// extra uses *after* the change-over point.
1123static void SetupCleanupBlockActivation(CodeGenFunction &CGF,
1124                                        EHScopeStack::stable_iterator C,
1125                                        ForActivation_t kind,
1126                                        llvm::Instruction *dominatingIP) {
1127  EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
1128
1129  // We always need the flag if we're activating the cleanup in a
1130  // conditional context, because we have to assume that the current
1131  // location doesn't necessarily dominate the cleanup's code.
1132  bool isActivatedInConditional =
1133    (kind == ForActivation && CGF.isInConditionalBranch());
1134
1135  bool needFlag = false;
1136
1137  // Calculate whether the cleanup was used:
1138
1139  //   - as a normal cleanup
1140  if (Scope.isNormalCleanup() &&
1141      (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
1142    Scope.setTestFlagInNormalCleanup();
1143    needFlag = true;
1144  }
1145
1146  //  - as an EH cleanup
1147  if (Scope.isEHCleanup() &&
1148      (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
1149    Scope.setTestFlagInEHCleanup();
1150    needFlag = true;
1151  }
1152
1153  // If it hasn't yet been used as either, we're done.
1154  if (!needFlag) return;
1155
1156  Address var = Scope.getActiveFlag();
1157  if (!var.isValid()) {
1158    var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), CharUnits::One(),
1159                               "cleanup.isactive");
1160    Scope.setActiveFlag(var);
1161
1162    assert(dominatingIP && "no existing variable and no dominating IP!");
1163
1164    // Initialize to true or false depending on whether it was
1165    // active up to this point.
1166    llvm::Constant *value = CGF.Builder.getInt1(kind == ForDeactivation);
1167
1168    // If we're in a conditional block, ignore the dominating IP and
1169    // use the outermost conditional branch.
1170    if (CGF.isInConditionalBranch()) {
1171      CGF.setBeforeOutermostConditional(value, var);
1172    } else {
1173      createStoreInstBefore(value, var, dominatingIP);
1174    }
1175  }
1176
1177  CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
1178}
1179
1180/// Activate a cleanup that was created in an inactivated state.
1181void CodeGenFunction::ActivateCleanupBlock(EHScopeStack::stable_iterator C,
1182                                           llvm::Instruction *dominatingIP) {
1183  assert(C != EHStack.stable_end() && "activating bottom of stack?");
1184  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1185  assert(!Scope.isActive() && "double activation");
1186
1187  SetupCleanupBlockActivation(*this, C, ForActivation, dominatingIP);
1188
1189  Scope.setActive(true);
1190}
1191
1192/// Deactive a cleanup that was created in an active state.
1193void CodeGenFunction::DeactivateCleanupBlock(EHScopeStack::stable_iterator C,
1194                                             llvm::Instruction *dominatingIP) {
1195  assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
1196  EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1197  assert(Scope.isActive() && "double deactivation");
1198
1199  // If it's the top of the stack, just pop it.
1200  if (C == EHStack.stable_begin()) {
1201    // If it's a normal cleanup, we need to pretend that the
1202    // fallthrough is unreachable.
1203    CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1204    PopCleanupBlock();
1205    Builder.restoreIP(SavedIP);
1206    return;
1207  }
1208
1209  // Otherwise, follow the general case.
1210  SetupCleanupBlockActivation(*this, C, ForDeactivation, dominatingIP);
1211
1212  Scope.setActive(false);
1213}
1214
1215Address CodeGenFunction::getNormalCleanupDestSlot() {
1216  if (!NormalCleanupDest)
1217    NormalCleanupDest =
1218      CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
1219  return Address(NormalCleanupDest, CharUnits::fromQuantity(4));
1220}
1221
1222/// Emits all the code to cause the given temporary to be cleaned up.
1223void CodeGenFunction::EmitCXXTemporary(const CXXTemporary *Temporary,
1224                                       QualType TempType,
1225                                       Address Ptr) {
1226  pushDestroy(NormalAndEHCleanup, Ptr, TempType, destroyCXXObject,
1227              /*useEHCleanup*/ true);
1228}
1229