contrib/llvm/tools/clang/lib/CodeGen/CGCleanup.cpp

   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
  23 using namespace clang;
  24 using namespace CodeGen;
  25
  26 bool DominatingValue<RValue>::saved_type::needsSaving(RValue rv) {
  27   if (rv.isScalar())
  28     return DominatingLLVMValue::needsSaving(rv.getScalarVal());
  29   if (rv.isAggregate())
  30     return DominatingLLVMValue::needsSaving(rv.getAggregateAddr());
  31   return true;
  32 }
  33
  34 DominatingValue<RValue>::saved_type
  35 DominatingValue<RValue>::saved_type::save(CodeGenFunction &CGF, RValue rv) {
  36   if (rv.isScalar()) {
  37     llvm::Value *V = rv.getScalarVal();
  38
  39     // These automatically dominate and don't need to be saved.
  40     if (!DominatingLLVMValue::needsSaving(V))
  41       return saved_type(V, ScalarLiteral);
  42
  43     // Everything else needs an alloca.
  44     llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
  45     CGF.Builder.CreateStore(V, addr);
  46     return saved_type(addr, ScalarAddress);
  47   }
  48
  49   if (rv.isComplex()) {
  50     CodeGenFunction::ComplexPairTy V = rv.getComplexVal();
  51     llvm::Type *ComplexTy =
  52       llvm::StructType::get(V.first->getType(), V.second->getType(),
  53                             (void*) 0);
  54     llvm::Value *addr = CGF.CreateTempAlloca(ComplexTy, "saved-complex");
  55     CGF.Builder.CreateStore(V.first, CGF.Builder.CreateStructGEP(addr, 0));
  56     CGF.Builder.CreateStore(V.second, CGF.Builder.CreateStructGEP(addr, 1));
  57     return saved_type(addr, ComplexAddress);
  58   }
  59
  60   assert(rv.isAggregate());
  61   llvm::Value *V = rv.getAggregateAddr(); // TODO: volatile?
  62   if (!DominatingLLVMValue::needsSaving(V))
  63     return saved_type(V, AggregateLiteral);
  64
  65   llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
  66   CGF.Builder.CreateStore(V, addr);
  67   return saved_type(addr, AggregateAddress);
  68 }
  69
  70 /// Given a saved r-value produced by SaveRValue, perform the code
  71 /// necessary to restore it to usability at the current insertion
  72 /// point.
  73 RValue DominatingValue<RValue>::saved_type::restore(CodeGenFunction &CGF) {
  74   switch (K) {
  75   case ScalarLiteral:
  76     return RValue::get(Value);
  77   case ScalarAddress:
  78     return RValue::get(CGF.Builder.CreateLoad(Value));
  79   case AggregateLiteral:
  80     return RValue::getAggregate(Value);
  81   case AggregateAddress:
  82     return RValue::getAggregate(CGF.Builder.CreateLoad(Value));
  83   case ComplexAddress: {
  84     llvm::Value *real =
  85       CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(Value, 0));
  86     llvm::Value *imag =
  87       CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(Value, 1));
  88     return RValue::getComplex(real, imag);
  89   }
  90   }
  91
  92   llvm_unreachable("bad saved r-value kind");
  93 }
  94
  95 /// Push an entry of the given size onto this protected-scope stack.
  96 char *EHScopeStack::allocate(size_t Size) {
  97   if (!StartOfBuffer) {
  98     unsigned Capacity = 1024;
  99     while (Capacity < Size) Capacity *= 2;
 100     StartOfBuffer = new char[Capacity];
 101     StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
 102   } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
 103     unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
 104     unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
 105
 106     unsigned NewCapacity = CurrentCapacity;
 107     do {
 108       NewCapacity *= 2;
 109     } while (NewCapacity < UsedCapacity + Size);
 110
 111     char *NewStartOfBuffer = new char[NewCapacity];
 112     char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
 113     char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
 114     memcpy(NewStartOfData, StartOfData, UsedCapacity);
 115     delete [] StartOfBuffer;
 116     StartOfBuffer = NewStartOfBuffer;
 117     EndOfBuffer = NewEndOfBuffer;
 118     StartOfData = NewStartOfData;
 119   }
 120
 121   assert(StartOfBuffer + Size <= StartOfData);
 122   StartOfData -= Size;
 123   return StartOfData;
 124 }
 125
 126 EHScopeStack::stable_iterator
 127 EHScopeStack::getInnermostActiveNormalCleanup() const {
 128   for (stable_iterator si = getInnermostNormalCleanup(), se = stable_end();
 129          si != se; ) {
 130     EHCleanupScope &cleanup = cast<EHCleanupScope>(*find(si));
 131     if (cleanup.isActive()) return si;
 132     si = cleanup.getEnclosingNormalCleanup();
 133   }
 134   return stable_end();
 135 }
 136
 137 EHScopeStack::stable_iterator EHScopeStack::getInnermostActiveEHScope() const {
 138   for (stable_iterator si = getInnermostEHScope(), se = stable_end();
 139          si != se; ) {
 140     // Skip over inactive cleanups.
 141     EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*find(si));
 142     if (cleanup && !cleanup->isActive()) {
 143       si = cleanup->getEnclosingEHScope();
 144       continue;
 145     }
 146
 147     // All other scopes are always active.
 148     return si;
 149   }
 150
 151   return stable_end();
 152 }
 153
 154
 155 void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
 156   assert(((Size % sizeof(void*)) == 0) && "cleanup type is misaligned");
 157   char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
 158   bool IsNormalCleanup = Kind & NormalCleanup;
 159   bool IsEHCleanup = Kind & EHCleanup;
 160   bool IsActive = !(Kind & InactiveCleanup);
 161   EHCleanupScope *Scope =
 162     new (Buffer) EHCleanupScope(IsNormalCleanup,
 163                                 IsEHCleanup,
 164                                 IsActive,
 165                                 Size,
 166                                 BranchFixups.size(),
 167                                 InnermostNormalCleanup,
 168                                 InnermostEHScope);
 169   if (IsNormalCleanup)
 170     InnermostNormalCleanup = stable_begin();
 171   if (IsEHCleanup)
 172     InnermostEHScope = stable_begin();
 173
 174   return Scope->getCleanupBuffer();
 175 }
 176
 177 void EHScopeStack::popCleanup() {
 178   assert(!empty() && "popping exception stack when not empty");
 179
 180   assert(isa<EHCleanupScope>(*begin()));
 181   EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
 182   InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
 183   InnermostEHScope = Cleanup.getEnclosingEHScope();
 184   StartOfData += Cleanup.getAllocatedSize();
 185
 186   // Destroy the cleanup.
 187   Cleanup.~EHCleanupScope();
 188
 189   // Check whether we can shrink the branch-fixups stack.
 190   if (!BranchFixups.empty()) {
 191     // If we no longer have any normal cleanups, all the fixups are
 192     // complete.
 193     if (!hasNormalCleanups())
 194       BranchFixups.clear();
 195
 196     // Otherwise we can still trim out unnecessary nulls.
 197     else
 198       popNullFixups();
 199   }
 200 }
 201
 202 EHFilterScope *EHScopeStack::pushFilter(unsigned numFilters) {
 203   assert(getInnermostEHScope() == stable_end());
 204   char *buffer = allocate(EHFilterScope::getSizeForNumFilters(numFilters));
 205   EHFilterScope *filter = new (buffer) EHFilterScope(numFilters);
 206   InnermostEHScope = stable_begin();
 207   return filter;
 208 }
 209
 210 void EHScopeStack::popFilter() {
 211   assert(!empty() && "popping exception stack when not empty");
 212
 213   EHFilterScope &filter = cast<EHFilterScope>(*begin());
 214   StartOfData += EHFilterScope::getSizeForNumFilters(filter.getNumFilters());
 215
 216   InnermostEHScope = filter.getEnclosingEHScope();
 217 }
 218
 219 EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) {
 220   char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers));
 221   EHCatchScope *scope =
 222     new (buffer) EHCatchScope(numHandlers, InnermostEHScope);
 223   InnermostEHScope = stable_begin();
 224   return scope;
 225 }
 226
 227 void EHScopeStack::pushTerminate() {
 228   char *Buffer = allocate(EHTerminateScope::getSize());
 229   new (Buffer) EHTerminateScope(InnermostEHScope);
 230   InnermostEHScope = stable_begin();
 231 }
 232
 233 /// Remove any 'null' fixups on the stack.  However, we can't pop more
 234 /// fixups than the fixup depth on the innermost normal cleanup, or
 235 /// else fixups that we try to add to that cleanup will end up in the
 236 /// wrong place.  We *could* try to shrink fixup depths, but that's
 237 /// actually a lot of work for little benefit.
 238 void EHScopeStack::popNullFixups() {
 239   // We expect this to only be called when there's still an innermost
 240   // normal cleanup;  otherwise there really shouldn't be any fixups.
 241   assert(hasNormalCleanups());
 242
 243   EHScopeStack::iterator it = find(InnermostNormalCleanup);
 244   unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
 245   assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
 246
 247   while (BranchFixups.size() > MinSize &&
 248          BranchFixups.back().Destination == 0)
 249     BranchFixups.pop_back();
 250 }
 251
 252 void CodeGenFunction::initFullExprCleanup() {
 253   // Create a variable to decide whether the cleanup needs to be run.
 254   llvm::AllocaInst *active
 255     = CreateTempAlloca(Builder.getInt1Ty(), "cleanup.cond");
 256
 257   // Initialize it to false at a site that's guaranteed to be run
 258   // before each evaluation.
 259   setBeforeOutermostConditional(Builder.getFalse(), active);
 260
 261   // Initialize it to true at the current location.
 262   Builder.CreateStore(Builder.getTrue(), active);
 263
 264   // Set that as the active flag in the cleanup.
 265   EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
 266   assert(cleanup.getActiveFlag() == 0 && "cleanup already has active flag?");
 267   cleanup.setActiveFlag(active);
 268
 269   if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
 270   if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
 271 }
 272
 273 void EHScopeStack::Cleanup::anchor() {}
 274
 275 /// All the branch fixups on the EH stack have propagated out past the
 276 /// outermost normal cleanup; resolve them all by adding cases to the
 277 /// given switch instruction.
 278 static void ResolveAllBranchFixups(CodeGenFunction &CGF,
 279                                    llvm::SwitchInst *Switch,
 280                                    llvm::BasicBlock *CleanupEntry) {
 281   llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
 282
 283   for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
 284     // Skip this fixup if its destination isn't set.
 285     BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
 286     if (Fixup.Destination == 0) continue;
 287
 288     // If there isn't an OptimisticBranchBlock, then InitialBranch is
 289     // still pointing directly to its destination; forward it to the
 290     // appropriate cleanup entry.  This is required in the specific
 291     // case of
 292     //   { std::string s; goto lbl; }
 293     //   lbl:
 294     // i.e. where there's an unresolved fixup inside a single cleanup
 295     // entry which we're currently popping.
 296     if (Fixup.OptimisticBranchBlock == 0) {
 297       new llvm::StoreInst(CGF.Builder.getInt32(Fixup.DestinationIndex),
 298                           CGF.getNormalCleanupDestSlot(),
 299                           Fixup.InitialBranch);
 300       Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
 301     }
 302
 303     // Don't add this case to the switch statement twice.
 304     if (!CasesAdded.insert(Fixup.Destination)) continue;
 305
 306     Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
 307                     Fixup.Destination);
 308   }
 309
 310   CGF.EHStack.clearFixups();
 311 }
 312
 313 /// Transitions the terminator of the given exit-block of a cleanup to
 314 /// be a cleanup switch.
 315 static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
 316                                                    llvm::BasicBlock *Block) {
 317   // If it's a branch, turn it into a switch whose default
 318   // destination is its original target.
 319   llvm::TerminatorInst *Term = Block->getTerminator();
 320   assert(Term && "can't transition block without terminator");
 321
 322   if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
 323     assert(Br->isUnconditional());
 324     llvm::LoadInst *Load =
 325       new llvm::LoadInst(CGF.getNormalCleanupDestSlot(), "cleanup.dest", Term);
 326     llvm::SwitchInst *Switch =
 327       llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
 328     Br->eraseFromParent();
 329     return Switch;
 330   } else {
 331     return cast<llvm::SwitchInst>(Term);
 332   }
 333 }
 334
 335 void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
 336   assert(Block && "resolving a null target block");
 337   if (!EHStack.getNumBranchFixups()) return;
 338
 339   assert(EHStack.hasNormalCleanups() &&
 340          "branch fixups exist with no normal cleanups on stack");
 341
 342   llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
 343   bool ResolvedAny = false;
 344
 345   for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
 346     // Skip this fixup if its destination doesn't match.
 347     BranchFixup &Fixup = EHStack.getBranchFixup(I);
 348     if (Fixup.Destination != Block) continue;
 349
 350     Fixup.Destination = 0;
 351     ResolvedAny = true;
 352
 353     // If it doesn't have an optimistic branch block, LatestBranch is
 354     // already pointing to the right place.
 355     llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
 356     if (!BranchBB)
 357       continue;
 358
 359     // Don't process the same optimistic branch block twice.
 360     if (!ModifiedOptimisticBlocks.insert(BranchBB))
 361       continue;
 362
 363     llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
 364
 365     // Add a case to the switch.
 366     Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
 367   }
 368
 369   if (ResolvedAny)
 370     EHStack.popNullFixups();
 371 }
 372
 373 /// Pops cleanup blocks until the given savepoint is reached.
 374 void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) {
 375   assert(Old.isValid());
 376
 377   while (EHStack.stable_begin() != Old) {
 378     EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
 379
 380     // As long as Old strictly encloses the scope's enclosing normal
 381     // cleanup, we're going to emit another normal cleanup which
 382     // fallthrough can propagate through.
 383     bool FallThroughIsBranchThrough =
 384       Old.strictlyEncloses(Scope.getEnclosingNormalCleanup());
 385
 386     PopCleanupBlock(FallThroughIsBranchThrough);
 387   }
 388 }
 389
 390 /// Pops cleanup blocks until the given savepoint is reached, then add the
 391 /// cleanups from the given savepoint in the lifetime-extended cleanups stack.
 392 void
 393 CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old,
 394                                   size_t OldLifetimeExtendedSize) {
 395   PopCleanupBlocks(Old);
 396
 397   // Move our deferred cleanups onto the EH stack.
 398   for (size_t I = OldLifetimeExtendedSize,
 399               E = LifetimeExtendedCleanupStack.size(); I != E; /**/) {
 400     // Alignment should be guaranteed by the vptrs in the individual cleanups.
 401     assert((I % llvm::alignOf<LifetimeExtendedCleanupHeader>() == 0) &&
 402            "misaligned cleanup stack entry");
 403
 404     LifetimeExtendedCleanupHeader &Header =
 405         reinterpret_cast<LifetimeExtendedCleanupHeader&>(
 406             LifetimeExtendedCleanupStack[I]);
 407     I += sizeof(Header);
 408
 409     EHStack.pushCopyOfCleanup(Header.getKind(),
 410                               &LifetimeExtendedCleanupStack[I],
 411                               Header.getSize());
 412     I += Header.getSize();
 413   }
 414   LifetimeExtendedCleanupStack.resize(OldLifetimeExtendedSize);
 415 }
 416
 417 static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
 418                                            EHCleanupScope &Scope) {
 419   assert(Scope.isNormalCleanup());
 420   llvm::BasicBlock *Entry = Scope.getNormalBlock();
 421   if (!Entry) {
 422     Entry = CGF.createBasicBlock("cleanup");
 423     Scope.setNormalBlock(Entry);
 424   }
 425   return Entry;
 426 }
 427
 428 /// Attempts to reduce a cleanup's entry block to a fallthrough.  This
 429 /// is basically llvm::MergeBlockIntoPredecessor, except
 430 /// simplified/optimized for the tighter constraints on cleanup blocks.
 431 ///
 432 /// Returns the new block, whatever it is.
 433 static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
 434                                               llvm::BasicBlock *Entry) {
 435   llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
 436   if (!Pred) return Entry;
 437
 438   llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
 439   if (!Br || Br->isConditional()) return Entry;
 440   assert(Br->getSuccessor(0) == Entry);
 441
 442   // If we were previously inserting at the end of the cleanup entry
 443   // block, we'll need to continue inserting at the end of the
 444   // predecessor.
 445   bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
 446   assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
 447
 448   // Kill the branch.
 449   Br->eraseFromParent();
 450
 451   // Replace all uses of the entry with the predecessor, in case there
 452   // are phis in the cleanup.
 453   Entry->replaceAllUsesWith(Pred);
 454
 455   // Merge the blocks.
 456   Pred->getInstList().splice(Pred->end(), Entry->getInstList());
 457
 458   // Kill the entry block.
 459   Entry->eraseFromParent();
 460
 461   if (WasInsertBlock)
 462     CGF.Builder.SetInsertPoint(Pred);
 463
 464   return Pred;
 465 }
 466
 467 static void EmitCleanup(CodeGenFunction &CGF,
 468                         EHScopeStack::Cleanup *Fn,
 469                         EHScopeStack::Cleanup::Flags flags,
 470                         llvm::Value *ActiveFlag) {
 471   // EH cleanups always occur within a terminate scope.
 472   if (flags.isForEHCleanup()) CGF.EHStack.pushTerminate();
 473
 474   // If there's an active flag, load it and skip the cleanup if it's
 475   // false.
 476   llvm::BasicBlock *ContBB = 0;
 477   if (ActiveFlag) {
 478     ContBB = CGF.createBasicBlock("cleanup.done");
 479     llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
 480     llvm::Value *IsActive
 481       = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
 482     CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
 483     CGF.EmitBlock(CleanupBB);
 484   }
 485
 486   // Ask the cleanup to emit itself.
 487   Fn->Emit(CGF, flags);
 488   assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
 489
 490   // Emit the continuation block if there was an active flag.
 491   if (ActiveFlag)
 492     CGF.EmitBlock(ContBB);
 493
 494   // Leave the terminate scope.
 495   if (flags.isForEHCleanup()) CGF.EHStack.popTerminate();
 496 }
 497
 498 static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
 499                                           llvm::BasicBlock *From,
 500                                           llvm::BasicBlock *To) {
 501   // Exit is the exit block of a cleanup, so it always terminates in
 502   // an unconditional branch or a switch.
 503   llvm::TerminatorInst *Term = Exit->getTerminator();
 504
 505   if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
 506     assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
 507     Br->setSuccessor(0, To);
 508   } else {
 509     llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
 510     for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
 511       if (Switch->getSuccessor(I) == From)
 512         Switch->setSuccessor(I, To);
 513   }
 514 }
 515
 516 /// We don't need a normal entry block for the given cleanup.
 517 /// Optimistic fixup branches can cause these blocks to come into
 518 /// existence anyway;  if so, destroy it.
 519 ///
 520 /// The validity of this transformation is very much specific to the
 521 /// exact ways in which we form branches to cleanup entries.
 522 static void destroyOptimisticNormalEntry(CodeGenFunction &CGF,
 523                                          EHCleanupScope &scope) {
 524   llvm::BasicBlock *entry = scope.getNormalBlock();
 525   if (!entry) return;
 526
 527   // Replace all the uses with unreachable.
 528   llvm::BasicBlock *unreachableBB = CGF.getUnreachableBlock();
 529   for (llvm::BasicBlock::use_iterator
 530          i = entry->use_begin(), e = entry->use_end(); i != e; ) {
 531     llvm::Use &use = i.getUse();
 532     ++i;
 533
 534     use.set(unreachableBB);
 535
 536     // The only uses should be fixup switches.
 537     llvm::SwitchInst *si = cast<llvm::SwitchInst>(use.getUser());
 538     if (si->getNumCases() == 1 && si->getDefaultDest() == unreachableBB) {
 539       // Replace the switch with a branch.
 540       llvm::BranchInst::Create(si->case_begin().getCaseSuccessor(), si);
 541
 542       // The switch operand is a load from the cleanup-dest alloca.
 543       llvm::LoadInst *condition = cast<llvm::LoadInst>(si->getCondition());
 544
 545       // Destroy the switch.
 546       si->eraseFromParent();
 547
 548       // Destroy the load.
 549       assert(condition->getOperand(0) == CGF.NormalCleanupDest);
 550       assert(condition->use_empty());
 551       condition->eraseFromParent();
 552     }
 553   }
 554
 555   assert(entry->use_empty());
 556   delete entry;
 557 }
 558
 559 /// Pops a cleanup block.  If the block includes a normal cleanup, the
 560 /// current insertion point is threaded through the cleanup, as are
 561 /// any branch fixups on the cleanup.
 562 void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
 563   assert(!EHStack.empty() && "cleanup stack is empty!");
 564   assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
 565   EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
 566   assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
 567
 568   // Remember activation information.
 569   bool IsActive = Scope.isActive();
 570   llvm::Value *NormalActiveFlag =
 571     Scope.shouldTestFlagInNormalCleanup() ? Scope.getActiveFlag() : 0;
 572   llvm::Value *EHActiveFlag =
 573     Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag() : 0;
 574
 575   // Check whether we need an EH cleanup.  This is only true if we've
 576   // generated a lazy EH cleanup block.
 577   llvm::BasicBlock *EHEntry = Scope.getCachedEHDispatchBlock();
 578   assert(Scope.hasEHBranches() == (EHEntry != 0));
 579   bool RequiresEHCleanup = (EHEntry != 0);
 580   EHScopeStack::stable_iterator EHParent = Scope.getEnclosingEHScope();
 581
 582   // Check the three conditions which might require a normal cleanup:
 583
 584   // - whether there are branch fix-ups through this cleanup
 585   unsigned FixupDepth = Scope.getFixupDepth();
 586   bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
 587
 588   // - whether there are branch-throughs or branch-afters
 589   bool HasExistingBranches = Scope.hasBranches();
 590
 591   // - whether there's a fallthrough
 592   llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
 593   bool HasFallthrough = (FallthroughSource != 0 && IsActive);
 594
 595   // Branch-through fall-throughs leave the insertion point set to the
 596   // end of the last cleanup, which points to the current scope.  The
 597   // rest of IR gen doesn't need to worry about this; it only happens
 598   // during the execution of PopCleanupBlocks().
 599   bool HasPrebranchedFallthrough =
 600     (FallthroughSource && FallthroughSource->getTerminator());
 601
 602   // If this is a normal cleanup, then having a prebranched
 603   // fallthrough implies that the fallthrough source unconditionally
 604   // jumps here.
 605   assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
 606          (Scope.getNormalBlock() &&
 607           FallthroughSource->getTerminator()->getSuccessor(0)
 608             == Scope.getNormalBlock()));
 609
 610   bool RequiresNormalCleanup = false;
 611   if (Scope.isNormalCleanup() &&
 612       (HasFixups || HasExistingBranches || HasFallthrough)) {
 613     RequiresNormalCleanup = true;
 614   }
 615
 616   // If we have a prebranched fallthrough into an inactive normal
 617   // cleanup, rewrite it so that it leads to the appropriate place.
 618   if (Scope.isNormalCleanup() && HasPrebranchedFallthrough && !IsActive) {
 619     llvm::BasicBlock *prebranchDest;
 620
 621     // If the prebranch is semantically branching through the next
 622     // cleanup, just forward it to the next block, leaving the
 623     // insertion point in the prebranched block.
 624     if (FallthroughIsBranchThrough) {
 625       EHScope &enclosing = *EHStack.find(Scope.getEnclosingNormalCleanup());
 626       prebranchDest = CreateNormalEntry(*this, cast<EHCleanupScope>(enclosing));
 627
 628     // Otherwise, we need to make a new block.  If the normal cleanup
 629     // isn't being used at all, we could actually reuse the normal
 630     // entry block, but this is simpler, and it avoids conflicts with
 631     // dead optimistic fixup branches.
 632     } else {
 633       prebranchDest = createBasicBlock("forwarded-prebranch");
 634       EmitBlock(prebranchDest);
 635     }
 636
 637     llvm::BasicBlock *normalEntry = Scope.getNormalBlock();
 638     assert(normalEntry && !normalEntry->use_empty());
 639
 640     ForwardPrebranchedFallthrough(FallthroughSource,
 641                                   normalEntry, prebranchDest);
 642   }
 643
 644   // If we don't need the cleanup at all, we're done.
 645   if (!RequiresNormalCleanup && !RequiresEHCleanup) {
 646     destroyOptimisticNormalEntry(*this, Scope);
 647     EHStack.popCleanup(); // safe because there are no fixups
 648     assert(EHStack.getNumBranchFixups() == 0 ||
 649            EHStack.hasNormalCleanups());
 650     return;
 651   }
 652
 653   // Copy the cleanup emission data out.  Note that SmallVector
 654   // guarantees maximal alignment for its buffer regardless of its
 655   // type parameter.
 656   SmallVector<char, 8*sizeof(void*)> CleanupBuffer;
 657   CleanupBuffer.reserve(Scope.getCleanupSize());
 658   memcpy(CleanupBuffer.data(),
 659          Scope.getCleanupBuffer(), Scope.getCleanupSize());
 660   CleanupBuffer.set_size(Scope.getCleanupSize());
 661   EHScopeStack::Cleanup *Fn =
 662     reinterpret_cast<EHScopeStack::Cleanup*>(CleanupBuffer.data());
 663
 664   EHScopeStack::Cleanup::Flags cleanupFlags;
 665   if (Scope.isNormalCleanup())
 666     cleanupFlags.setIsNormalCleanupKind();
 667   if (Scope.isEHCleanup())
 668     cleanupFlags.setIsEHCleanupKind();
 669
 670   if (!RequiresNormalCleanup) {
 671     destroyOptimisticNormalEntry(*this, Scope);
 672     EHStack.popCleanup();
 673   } else {
 674     // If we have a fallthrough and no other need for the cleanup,
 675     // emit it directly.
 676     if (HasFallthrough && !HasPrebranchedFallthrough &&
 677         !HasFixups && !HasExistingBranches) {
 678
 679       destroyOptimisticNormalEntry(*this, Scope);
 680       EHStack.popCleanup();
 681
 682       EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
 683
 684     // Otherwise, the best approach is to thread everything through
 685     // the cleanup block and then try to clean up after ourselves.
 686     } else {
 687       // Force the entry block to exist.
 688       llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
 689
 690       // I.  Set up the fallthrough edge in.
 691
 692       CGBuilderTy::InsertPoint savedInactiveFallthroughIP;
 693
 694       // If there's a fallthrough, we need to store the cleanup
 695       // destination index.  For fall-throughs this is always zero.
 696       if (HasFallthrough) {
 697         if (!HasPrebranchedFallthrough)
 698           Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
 699
 700       // Otherwise, save and clear the IP if we don't have fallthrough
 701       // because the cleanup is inactive.
 702       } else if (FallthroughSource) {
 703         assert(!IsActive && "source without fallthrough for active cleanup");
 704         savedInactiveFallthroughIP = Builder.saveAndClearIP();
 705       }
 706
 707       // II.  Emit the entry block.  This implicitly branches to it if
 708       // we have fallthrough.  All the fixups and existing branches
 709       // should already be branched to it.
 710       EmitBlock(NormalEntry);
 711
 712       // III.  Figure out where we're going and build the cleanup
 713       // epilogue.
 714
 715       bool HasEnclosingCleanups =
 716         (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
 717
 718       // Compute the branch-through dest if we need it:
 719       //   - if there are branch-throughs threaded through the scope
 720       //   - if fall-through is a branch-through
 721       //   - if there are fixups that will be optimistically forwarded
 722       //     to the enclosing cleanup
 723       llvm::BasicBlock *BranchThroughDest = 0;
 724       if (Scope.hasBranchThroughs() ||
 725           (FallthroughSource && FallthroughIsBranchThrough) ||
 726           (HasFixups && HasEnclosingCleanups)) {
 727         assert(HasEnclosingCleanups);
 728         EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
 729         BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
 730       }
 731
 732       llvm::BasicBlock *FallthroughDest = 0;
 733       SmallVector<llvm::Instruction*, 2> InstsToAppend;
 734
 735       // If there's exactly one branch-after and no other threads,
 736       // we can route it without a switch.
 737       if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
 738           Scope.getNumBranchAfters() == 1) {
 739         assert(!BranchThroughDest || !IsActive);
 740
 741         // TODO: clean up the possibly dead stores to the cleanup dest slot.
 742         llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
 743         InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
 744
 745       // Build a switch-out if we need it:
 746       //   - if there are branch-afters threaded through the scope
 747       //   - if fall-through is a branch-after
 748       //   - if there are fixups that have nowhere left to go and
 749       //     so must be immediately resolved
 750       } else if (Scope.getNumBranchAfters() ||
 751                  (HasFallthrough && !FallthroughIsBranchThrough) ||
 752                  (HasFixups && !HasEnclosingCleanups)) {
 753
 754         llvm::BasicBlock *Default =
 755           (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
 756
 757         // TODO: base this on the number of branch-afters and fixups
 758         const unsigned SwitchCapacity = 10;
 759
 760         llvm::LoadInst *Load =
 761           new llvm::LoadInst(getNormalCleanupDestSlot(), "cleanup.dest");
 762         llvm::SwitchInst *Switch =
 763           llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
 764
 765         InstsToAppend.push_back(Load);
 766         InstsToAppend.push_back(Switch);
 767
 768         // Branch-after fallthrough.
 769         if (FallthroughSource && !FallthroughIsBranchThrough) {
 770           FallthroughDest = createBasicBlock("cleanup.cont");
 771           if (HasFallthrough)
 772             Switch->addCase(Builder.getInt32(0), FallthroughDest);
 773         }
 774
 775         for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
 776           Switch->addCase(Scope.getBranchAfterIndex(I),
 777                           Scope.getBranchAfterBlock(I));
 778         }
 779
 780         // If there aren't any enclosing cleanups, we can resolve all
 781         // the fixups now.
 782         if (HasFixups && !HasEnclosingCleanups)
 783           ResolveAllBranchFixups(*this, Switch, NormalEntry);
 784       } else {
 785         // We should always have a branch-through destination in this case.
 786         assert(BranchThroughDest);
 787         InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
 788       }
 789
 790       // IV.  Pop the cleanup and emit it.
 791       EHStack.popCleanup();
 792       assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
 793
 794       EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
 795
 796       // Append the prepared cleanup prologue from above.
 797       llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
 798       for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
 799         NormalExit->getInstList().push_back(InstsToAppend[I]);
 800
 801       // Optimistically hope that any fixups will continue falling through.
 802       for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
 803            I < E; ++I) {
 804         BranchFixup &Fixup = EHStack.getBranchFixup(I);
 805         if (!Fixup.Destination) continue;
 806         if (!Fixup.OptimisticBranchBlock) {
 807           new llvm::StoreInst(Builder.getInt32(Fixup.DestinationIndex),
 808                               getNormalCleanupDestSlot(),
 809                               Fixup.InitialBranch);
 810           Fixup.InitialBranch->setSuccessor(0, NormalEntry);
 811         }
 812         Fixup.OptimisticBranchBlock = NormalExit;
 813       }
 814
 815       // V.  Set up the fallthrough edge out.
 816
 817       // Case 1: a fallthrough source exists but doesn't branch to the
 818       // cleanup because the cleanup is inactive.
 819       if (!HasFallthrough && FallthroughSource) {
 820         // Prebranched fallthrough was forwarded earlier.
 821         // Non-prebranched fallthrough doesn't need to be forwarded.
 822         // Either way, all we need to do is restore the IP we cleared before.
 823         assert(!IsActive);
 824         Builder.restoreIP(savedInactiveFallthroughIP);
 825
 826       // Case 2: a fallthrough source exists and should branch to the
 827       // cleanup, but we're not supposed to branch through to the next
 828       // cleanup.
 829       } else if (HasFallthrough && FallthroughDest) {
 830         assert(!FallthroughIsBranchThrough);
 831         EmitBlock(FallthroughDest);
 832
 833       // Case 3: a fallthrough source exists and should branch to the
 834       // cleanup and then through to the next.
 835       } else if (HasFallthrough) {
 836         // Everything is already set up for this.
 837
 838       // Case 4: no fallthrough source exists.
 839       } else {
 840         Builder.ClearInsertionPoint();
 841       }
 842
 843       // VI.  Assorted cleaning.
 844
 845       // Check whether we can merge NormalEntry into a single predecessor.
 846       // This might invalidate (non-IR) pointers to NormalEntry.
 847       llvm::BasicBlock *NewNormalEntry =
 848         SimplifyCleanupEntry(*this, NormalEntry);
 849
 850       // If it did invalidate those pointers, and NormalEntry was the same
 851       // as NormalExit, go back and patch up the fixups.
 852       if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
 853         for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
 854                I < E; ++I)
 855           EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
 856     }
 857   }
 858
 859   assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
 860
 861   // Emit the EH cleanup if required.
 862   if (RequiresEHCleanup) {
 863     if (CGDebugInfo *DI = getDebugInfo())
 864       DI->EmitLocation(Builder, CurEHLocation);
 865
 866     CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
 867
 868     EmitBlock(EHEntry);
 869
 870     // We only actually emit the cleanup code if the cleanup is either
 871     // active or was used before it was deactivated.
 872     if (EHActiveFlag || IsActive) {
 873
 874       cleanupFlags.setIsForEHCleanup();
 875       EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
 876     }
 877
 878     Builder.CreateBr(getEHDispatchBlock(EHParent));
 879
 880     Builder.restoreIP(SavedIP);
 881
 882     SimplifyCleanupEntry(*this, EHEntry);
 883   }
 884 }
 885
 886 /// isObviouslyBranchWithoutCleanups - Return true if a branch to the
 887 /// specified destination obviously has no cleanups to run.  'false' is always
 888 /// a conservatively correct answer for this method.
 889 bool CodeGenFunction::isObviouslyBranchWithoutCleanups(JumpDest Dest) const {
 890   assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
 891          && "stale jump destination");
 892
 893   // Calculate the innermost active normal cleanup.
 894   EHScopeStack::stable_iterator TopCleanup =
 895     EHStack.getInnermostActiveNormalCleanup();
 896
 897   // If we're not in an active normal cleanup scope, or if the
 898   // destination scope is within the innermost active normal cleanup
 899   // scope, we don't need to worry about fixups.
 900   if (TopCleanup == EHStack.stable_end() ||
 901       TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid
 902     return true;
 903
 904   // Otherwise, we might need some cleanups.
 905   return false;
 906 }
 907
 908
 909 /// Terminate the current block by emitting a branch which might leave
 910 /// the current cleanup-protected scope.  The target scope may not yet
 911 /// be known, in which case this will require a fixup.
 912 ///
 913 /// As a side-effect, this method clears the insertion point.
 914 void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) {
 915   assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
 916          && "stale jump destination");
 917
 918   if (!HaveInsertPoint())
 919     return;
 920
 921   // Create the branch.
 922   llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
 923
 924   // Calculate the innermost active normal cleanup.
 925   EHScopeStack::stable_iterator
 926     TopCleanup = EHStack.getInnermostActiveNormalCleanup();
 927
 928   // If we're not in an active normal cleanup scope, or if the
 929   // destination scope is within the innermost active normal cleanup
 930   // scope, we don't need to worry about fixups.
 931   if (TopCleanup == EHStack.stable_end() ||
 932       TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
 933     Builder.ClearInsertionPoint();
 934     return;
 935   }
 936
 937   // If we can't resolve the destination cleanup scope, just add this
 938   // to the current cleanup scope as a branch fixup.
 939   if (!Dest.getScopeDepth().isValid()) {
 940     BranchFixup &Fixup = EHStack.addBranchFixup();
 941     Fixup.Destination = Dest.getBlock();
 942     Fixup.DestinationIndex = Dest.getDestIndex();
 943     Fixup.InitialBranch = BI;
 944     Fixup.OptimisticBranchBlock = 0;
 945
 946     Builder.ClearInsertionPoint();
 947     return;
 948   }
 949
 950   // Otherwise, thread through all the normal cleanups in scope.
 951
 952   // Store the index at the start.
 953   llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
 954   new llvm::StoreInst(Index, getNormalCleanupDestSlot(), BI);
 955
 956   // Adjust BI to point to the first cleanup block.
 957   {
 958     EHCleanupScope &Scope =
 959       cast<EHCleanupScope>(*EHStack.find(TopCleanup));
 960     BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
 961   }
 962
 963   // Add this destination to all the scopes involved.
 964   EHScopeStack::stable_iterator I = TopCleanup;
 965   EHScopeStack::stable_iterator E = Dest.getScopeDepth();
 966   if (E.strictlyEncloses(I)) {
 967     while (true) {
 968       EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
 969       assert(Scope.isNormalCleanup());
 970       I = Scope.getEnclosingNormalCleanup();
 971
 972       // If this is the last cleanup we're propagating through, tell it
 973       // that there's a resolved jump moving through it.
 974       if (!E.strictlyEncloses(I)) {
 975         Scope.addBranchAfter(Index, Dest.getBlock());
 976         break;
 977       }
 978
 979       // Otherwise, tell the scope that there's a jump propoagating
 980       // through it.  If this isn't new information, all the rest of
 981       // the work has been done before.
 982       if (!Scope.addBranchThrough(Dest.getBlock()))
 983         break;
 984     }
 985   }
 986
 987   Builder.ClearInsertionPoint();
 988 }
 989
 990 static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack,
 991                                   EHScopeStack::stable_iterator C) {
 992   // If we needed a normal block for any reason, that counts.
 993   if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
 994     return true;
 995
 996   // Check whether any enclosed cleanups were needed.
 997   for (EHScopeStack::stable_iterator
 998          I = EHStack.getInnermostNormalCleanup();
 999          I != C; ) {
1000     assert(C.strictlyEncloses(I));
1001     EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
1002     if (S.getNormalBlock()) return true;
1003     I = S.getEnclosingNormalCleanup();
1004   }
1005
1006   return false;
1007 }
1008
1009 static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
1010                               EHScopeStack::stable_iterator cleanup) {
1011   // If we needed an EH block for any reason, that counts.
1012   if (EHStack.find(cleanup)->hasEHBranches())
1013     return true;
1014
1015   // Check whether any enclosed cleanups were needed.
1016   for (EHScopeStack::stable_iterator
1017          i = EHStack.getInnermostEHScope(); i != cleanup; ) {
1018     assert(cleanup.strictlyEncloses(i));
1019
1020     EHScope &scope = *EHStack.find(i);
1021     if (scope.hasEHBranches())
1022       return true;
1023
1024     i = scope.getEnclosingEHScope();
1025   }
1026
1027   return false;
1028 }
1029
1030 enum ForActivation_t {
1031   ForActivation,
1032   ForDeactivation
1033 };
1034
1035 /// The given cleanup block is changing activation state.  Configure a
1036 /// cleanup variable if necessary.
1037 ///
1038 /// It would be good if we had some way of determining if there were
1039 /// extra uses *after* the change-over point.
1040 static void SetupCleanupBlockActivation(CodeGenFunction &CGF,
1041                                         EHScopeStack::stable_iterator C,
1042                                         ForActivation_t kind,
1043                                         llvm::Instruction *dominatingIP) {
1044   EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
1045
1046   // We always need the flag if we're activating the cleanup in a
1047   // conditional context, because we have to assume that the current
1048   // location doesn't necessarily dominate the cleanup's code.
1049   bool isActivatedInConditional =
1050     (kind == ForActivation && CGF.isInConditionalBranch());
1051
1052   bool needFlag = false;
1053
1054   // Calculate whether the cleanup was used:
1055
1056   //   - as a normal cleanup
1057   if (Scope.isNormalCleanup() &&
1058       (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
1059     Scope.setTestFlagInNormalCleanup();
1060     needFlag = true;
1061   }
1062
1063   //  - as an EH cleanup
1064   if (Scope.isEHCleanup() &&
1065       (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
1066     Scope.setTestFlagInEHCleanup();
1067     needFlag = true;
1068   }
1069
1070   // If it hasn't yet been used as either, we're done.
1071   if (!needFlag) return;
1072
1073   llvm::AllocaInst *var = Scope.getActiveFlag();
1074   if (!var) {
1075     var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "cleanup.isactive");
1076     Scope.setActiveFlag(var);
1077
1078     assert(dominatingIP && "no existing variable and no dominating IP!");
1079
1080     // Initialize to true or false depending on whether it was
1081     // active up to this point.
1082     llvm::Value *value = CGF.Builder.getInt1(kind == ForDeactivation);
1083
1084     // If we're in a conditional block, ignore the dominating IP and
1085     // use the outermost conditional branch.
1086     if (CGF.isInConditionalBranch()) {
1087       CGF.setBeforeOutermostConditional(value, var);
1088     } else {
1089       new llvm::StoreInst(value, var, dominatingIP);
1090     }
1091   }
1092
1093   CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
1094 }
1095
1096 /// Activate a cleanup that was created in an inactivated state.
1097 void CodeGenFunction::ActivateCleanupBlock(EHScopeStack::stable_iterator C,
1098                                            llvm::Instruction *dominatingIP) {
1099   assert(C != EHStack.stable_end() && "activating bottom of stack?");
1100   EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1101   assert(!Scope.isActive() && "double activation");
1102
1103   SetupCleanupBlockActivation(*this, C, ForActivation, dominatingIP);
1104
1105   Scope.setActive(true);
1106 }
1107
1108 /// Deactive a cleanup that was created in an active state.
1109 void CodeGenFunction::DeactivateCleanupBlock(EHScopeStack::stable_iterator C,
1110                                              llvm::Instruction *dominatingIP) {
1111   assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
1112   EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1113   assert(Scope.isActive() && "double deactivation");
1114
1115   // If it's the top of the stack, just pop it.
1116   if (C == EHStack.stable_begin()) {
1117     // If it's a normal cleanup, we need to pretend that the
1118     // fallthrough is unreachable.
1119     CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1120     PopCleanupBlock();
1121     Builder.restoreIP(SavedIP);
1122     return;
1123   }
1124
1125   // Otherwise, follow the general case.
1126   SetupCleanupBlockActivation(*this, C, ForDeactivation, dominatingIP);
1127
1128   Scope.setActive(false);
1129 }
1130
1131 llvm::Value *CodeGenFunction::getNormalCleanupDestSlot() {
1132   if (!NormalCleanupDest)
1133     NormalCleanupDest =
1134       CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
1135   return NormalCleanupDest;
1136 }
1137
1138 /// Emits all the code to cause the given temporary to be cleaned up.
1139 void CodeGenFunction::EmitCXXTemporary(const CXXTemporary *Temporary,
1140                                        QualType TempType,
1141                                        llvm::Value *Ptr) {
1142   pushDestroy(NormalAndEHCleanup, Ptr, TempType, destroyCXXObject,
1143               /*useEHCleanup*/ true);
1144 }