John McCall | 36f893c | 2011-01-28 11:13:47 +0000 | [diff] [blame] | 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 "CodeGenFunction.h" |
| 21 | #include "CGCleanup.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 | const llvm::Type *ComplexTy = |
Chris Lattner | 7650d95 | 2011-06-18 22:49:11 +0000 | [diff] [blame^] | 52 | llvm::StructType::get(V.first->getType(), V.second->getType(), |
John McCall | 36f893c | 2011-01-28 11:13:47 +0000 | [diff] [blame] | 53 | (void*) 0); |
| 54 | llvm::Value *addr = CGF.CreateTempAlloca(ComplexTy, "saved-complex"); |
| 55 | CGF.StoreComplexToAddr(V, addr, /*volatile*/ false); |
| 56 | return saved_type(addr, ComplexAddress); |
| 57 | } |
| 58 | |
| 59 | assert(rv.isAggregate()); |
| 60 | llvm::Value *V = rv.getAggregateAddr(); // TODO: volatile? |
| 61 | if (!DominatingLLVMValue::needsSaving(V)) |
| 62 | return saved_type(V, AggregateLiteral); |
| 63 | |
| 64 | llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue"); |
| 65 | CGF.Builder.CreateStore(V, addr); |
| 66 | return saved_type(addr, AggregateAddress); |
| 67 | } |
| 68 | |
| 69 | /// Given a saved r-value produced by SaveRValue, perform the code |
| 70 | /// necessary to restore it to usability at the current insertion |
| 71 | /// point. |
| 72 | RValue DominatingValue<RValue>::saved_type::restore(CodeGenFunction &CGF) { |
| 73 | switch (K) { |
| 74 | case ScalarLiteral: |
| 75 | return RValue::get(Value); |
| 76 | case ScalarAddress: |
| 77 | return RValue::get(CGF.Builder.CreateLoad(Value)); |
| 78 | case AggregateLiteral: |
| 79 | return RValue::getAggregate(Value); |
| 80 | case AggregateAddress: |
| 81 | return RValue::getAggregate(CGF.Builder.CreateLoad(Value)); |
| 82 | case ComplexAddress: |
| 83 | return RValue::getComplex(CGF.LoadComplexFromAddr(Value, false)); |
| 84 | } |
| 85 | |
| 86 | llvm_unreachable("bad saved r-value kind"); |
| 87 | return RValue(); |
| 88 | } |
| 89 | |
| 90 | /// Push an entry of the given size onto this protected-scope stack. |
| 91 | char *EHScopeStack::allocate(size_t Size) { |
| 92 | if (!StartOfBuffer) { |
| 93 | unsigned Capacity = 1024; |
| 94 | while (Capacity < Size) Capacity *= 2; |
| 95 | StartOfBuffer = new char[Capacity]; |
| 96 | StartOfData = EndOfBuffer = StartOfBuffer + Capacity; |
| 97 | } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) { |
| 98 | unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer; |
| 99 | unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer); |
| 100 | |
| 101 | unsigned NewCapacity = CurrentCapacity; |
| 102 | do { |
| 103 | NewCapacity *= 2; |
| 104 | } while (NewCapacity < UsedCapacity + Size); |
| 105 | |
| 106 | char *NewStartOfBuffer = new char[NewCapacity]; |
| 107 | char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity; |
| 108 | char *NewStartOfData = NewEndOfBuffer - UsedCapacity; |
| 109 | memcpy(NewStartOfData, StartOfData, UsedCapacity); |
| 110 | delete [] StartOfBuffer; |
| 111 | StartOfBuffer = NewStartOfBuffer; |
| 112 | EndOfBuffer = NewEndOfBuffer; |
| 113 | StartOfData = NewStartOfData; |
| 114 | } |
| 115 | |
| 116 | assert(StartOfBuffer + Size <= StartOfData); |
| 117 | StartOfData -= Size; |
| 118 | return StartOfData; |
| 119 | } |
| 120 | |
| 121 | EHScopeStack::stable_iterator |
| 122 | EHScopeStack::getEnclosingEHCleanup(iterator it) const { |
| 123 | assert(it != end()); |
| 124 | do { |
| 125 | if (isa<EHCleanupScope>(*it)) { |
| 126 | if (cast<EHCleanupScope>(*it).isEHCleanup()) |
| 127 | return stabilize(it); |
| 128 | return cast<EHCleanupScope>(*it).getEnclosingEHCleanup(); |
| 129 | } |
| 130 | ++it; |
| 131 | } while (it != end()); |
| 132 | return stable_end(); |
| 133 | } |
| 134 | |
| 135 | |
| 136 | void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) { |
| 137 | assert(((Size % sizeof(void*)) == 0) && "cleanup type is misaligned"); |
| 138 | char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size)); |
| 139 | bool IsNormalCleanup = Kind & NormalCleanup; |
| 140 | bool IsEHCleanup = Kind & EHCleanup; |
| 141 | bool IsActive = !(Kind & InactiveCleanup); |
| 142 | EHCleanupScope *Scope = |
| 143 | new (Buffer) EHCleanupScope(IsNormalCleanup, |
| 144 | IsEHCleanup, |
| 145 | IsActive, |
| 146 | Size, |
| 147 | BranchFixups.size(), |
| 148 | InnermostNormalCleanup, |
| 149 | InnermostEHCleanup); |
| 150 | if (IsNormalCleanup) |
| 151 | InnermostNormalCleanup = stable_begin(); |
| 152 | if (IsEHCleanup) |
| 153 | InnermostEHCleanup = stable_begin(); |
| 154 | |
| 155 | return Scope->getCleanupBuffer(); |
| 156 | } |
| 157 | |
| 158 | void EHScopeStack::popCleanup() { |
| 159 | assert(!empty() && "popping exception stack when not empty"); |
| 160 | |
| 161 | assert(isa<EHCleanupScope>(*begin())); |
| 162 | EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin()); |
| 163 | InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup(); |
| 164 | InnermostEHCleanup = Cleanup.getEnclosingEHCleanup(); |
| 165 | StartOfData += Cleanup.getAllocatedSize(); |
| 166 | |
| 167 | if (empty()) NextEHDestIndex = FirstEHDestIndex; |
| 168 | |
| 169 | // Destroy the cleanup. |
| 170 | Cleanup.~EHCleanupScope(); |
| 171 | |
| 172 | // Check whether we can shrink the branch-fixups stack. |
| 173 | if (!BranchFixups.empty()) { |
| 174 | // If we no longer have any normal cleanups, all the fixups are |
| 175 | // complete. |
| 176 | if (!hasNormalCleanups()) |
| 177 | BranchFixups.clear(); |
| 178 | |
| 179 | // Otherwise we can still trim out unnecessary nulls. |
| 180 | else |
| 181 | popNullFixups(); |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | EHFilterScope *EHScopeStack::pushFilter(unsigned NumFilters) { |
| 186 | char *Buffer = allocate(EHFilterScope::getSizeForNumFilters(NumFilters)); |
| 187 | CatchDepth++; |
| 188 | return new (Buffer) EHFilterScope(NumFilters); |
| 189 | } |
| 190 | |
| 191 | void EHScopeStack::popFilter() { |
| 192 | assert(!empty() && "popping exception stack when not empty"); |
| 193 | |
| 194 | EHFilterScope &Filter = cast<EHFilterScope>(*begin()); |
| 195 | StartOfData += EHFilterScope::getSizeForNumFilters(Filter.getNumFilters()); |
| 196 | |
| 197 | if (empty()) NextEHDestIndex = FirstEHDestIndex; |
| 198 | |
| 199 | assert(CatchDepth > 0 && "mismatched filter push/pop"); |
| 200 | CatchDepth--; |
| 201 | } |
| 202 | |
| 203 | EHCatchScope *EHScopeStack::pushCatch(unsigned NumHandlers) { |
| 204 | char *Buffer = allocate(EHCatchScope::getSizeForNumHandlers(NumHandlers)); |
| 205 | CatchDepth++; |
| 206 | EHCatchScope *Scope = new (Buffer) EHCatchScope(NumHandlers); |
| 207 | for (unsigned I = 0; I != NumHandlers; ++I) |
| 208 | Scope->getHandlers()[I].Index = getNextEHDestIndex(); |
| 209 | return Scope; |
| 210 | } |
| 211 | |
| 212 | void EHScopeStack::pushTerminate() { |
| 213 | char *Buffer = allocate(EHTerminateScope::getSize()); |
| 214 | CatchDepth++; |
| 215 | new (Buffer) EHTerminateScope(getNextEHDestIndex()); |
| 216 | } |
| 217 | |
| 218 | /// Remove any 'null' fixups on the stack. However, we can't pop more |
| 219 | /// fixups than the fixup depth on the innermost normal cleanup, or |
| 220 | /// else fixups that we try to add to that cleanup will end up in the |
| 221 | /// wrong place. We *could* try to shrink fixup depths, but that's |
| 222 | /// actually a lot of work for little benefit. |
| 223 | void EHScopeStack::popNullFixups() { |
| 224 | // We expect this to only be called when there's still an innermost |
| 225 | // normal cleanup; otherwise there really shouldn't be any fixups. |
| 226 | assert(hasNormalCleanups()); |
| 227 | |
| 228 | EHScopeStack::iterator it = find(InnermostNormalCleanup); |
| 229 | unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth(); |
| 230 | assert(BranchFixups.size() >= MinSize && "fixup stack out of order"); |
| 231 | |
| 232 | while (BranchFixups.size() > MinSize && |
| 233 | BranchFixups.back().Destination == 0) |
| 234 | BranchFixups.pop_back(); |
| 235 | } |
| 236 | |
| 237 | void CodeGenFunction::initFullExprCleanup() { |
| 238 | // Create a variable to decide whether the cleanup needs to be run. |
| 239 | llvm::AllocaInst *active |
| 240 | = CreateTempAlloca(Builder.getInt1Ty(), "cleanup.cond"); |
| 241 | |
| 242 | // Initialize it to false at a site that's guaranteed to be run |
| 243 | // before each evaluation. |
| 244 | llvm::BasicBlock *block = OutermostConditional->getStartingBlock(); |
| 245 | new llvm::StoreInst(Builder.getFalse(), active, &block->back()); |
| 246 | |
| 247 | // Initialize it to true at the current location. |
| 248 | Builder.CreateStore(Builder.getTrue(), active); |
| 249 | |
| 250 | // Set that as the active flag in the cleanup. |
| 251 | EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin()); |
| 252 | assert(cleanup.getActiveFlag() == 0 && "cleanup already has active flag?"); |
| 253 | cleanup.setActiveFlag(active); |
| 254 | |
| 255 | if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup(); |
| 256 | if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup(); |
| 257 | } |
| 258 | |
| 259 | EHScopeStack::Cleanup::~Cleanup() { |
| 260 | llvm_unreachable("Cleanup is indestructable"); |
| 261 | } |
| 262 | |
| 263 | /// All the branch fixups on the EH stack have propagated out past the |
| 264 | /// outermost normal cleanup; resolve them all by adding cases to the |
| 265 | /// given switch instruction. |
| 266 | static void ResolveAllBranchFixups(CodeGenFunction &CGF, |
| 267 | llvm::SwitchInst *Switch, |
| 268 | llvm::BasicBlock *CleanupEntry) { |
| 269 | llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded; |
| 270 | |
| 271 | for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) { |
| 272 | // Skip this fixup if its destination isn't set. |
| 273 | BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I); |
| 274 | if (Fixup.Destination == 0) continue; |
| 275 | |
| 276 | // If there isn't an OptimisticBranchBlock, then InitialBranch is |
| 277 | // still pointing directly to its destination; forward it to the |
| 278 | // appropriate cleanup entry. This is required in the specific |
| 279 | // case of |
| 280 | // { std::string s; goto lbl; } |
| 281 | // lbl: |
| 282 | // i.e. where there's an unresolved fixup inside a single cleanup |
| 283 | // entry which we're currently popping. |
| 284 | if (Fixup.OptimisticBranchBlock == 0) { |
| 285 | new llvm::StoreInst(CGF.Builder.getInt32(Fixup.DestinationIndex), |
| 286 | CGF.getNormalCleanupDestSlot(), |
| 287 | Fixup.InitialBranch); |
| 288 | Fixup.InitialBranch->setSuccessor(0, CleanupEntry); |
| 289 | } |
| 290 | |
| 291 | // Don't add this case to the switch statement twice. |
| 292 | if (!CasesAdded.insert(Fixup.Destination)) continue; |
| 293 | |
| 294 | Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex), |
| 295 | Fixup.Destination); |
| 296 | } |
| 297 | |
| 298 | CGF.EHStack.clearFixups(); |
| 299 | } |
| 300 | |
| 301 | /// Transitions the terminator of the given exit-block of a cleanup to |
| 302 | /// be a cleanup switch. |
| 303 | static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF, |
| 304 | llvm::BasicBlock *Block) { |
| 305 | // If it's a branch, turn it into a switch whose default |
| 306 | // destination is its original target. |
| 307 | llvm::TerminatorInst *Term = Block->getTerminator(); |
| 308 | assert(Term && "can't transition block without terminator"); |
| 309 | |
| 310 | if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) { |
| 311 | assert(Br->isUnconditional()); |
| 312 | llvm::LoadInst *Load = |
| 313 | new llvm::LoadInst(CGF.getNormalCleanupDestSlot(), "cleanup.dest", Term); |
| 314 | llvm::SwitchInst *Switch = |
| 315 | llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block); |
| 316 | Br->eraseFromParent(); |
| 317 | return Switch; |
| 318 | } else { |
| 319 | return cast<llvm::SwitchInst>(Term); |
| 320 | } |
| 321 | } |
| 322 | |
| 323 | void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) { |
| 324 | assert(Block && "resolving a null target block"); |
| 325 | if (!EHStack.getNumBranchFixups()) return; |
| 326 | |
| 327 | assert(EHStack.hasNormalCleanups() && |
| 328 | "branch fixups exist with no normal cleanups on stack"); |
| 329 | |
| 330 | llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks; |
| 331 | bool ResolvedAny = false; |
| 332 | |
| 333 | for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) { |
| 334 | // Skip this fixup if its destination doesn't match. |
| 335 | BranchFixup &Fixup = EHStack.getBranchFixup(I); |
| 336 | if (Fixup.Destination != Block) continue; |
| 337 | |
| 338 | Fixup.Destination = 0; |
| 339 | ResolvedAny = true; |
| 340 | |
| 341 | // If it doesn't have an optimistic branch block, LatestBranch is |
| 342 | // already pointing to the right place. |
| 343 | llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock; |
| 344 | if (!BranchBB) |
| 345 | continue; |
| 346 | |
| 347 | // Don't process the same optimistic branch block twice. |
| 348 | if (!ModifiedOptimisticBlocks.insert(BranchBB)) |
| 349 | continue; |
| 350 | |
| 351 | llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB); |
| 352 | |
| 353 | // Add a case to the switch. |
| 354 | Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block); |
| 355 | } |
| 356 | |
| 357 | if (ResolvedAny) |
| 358 | EHStack.popNullFixups(); |
| 359 | } |
| 360 | |
| 361 | /// Pops cleanup blocks until the given savepoint is reached. |
| 362 | void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) { |
| 363 | assert(Old.isValid()); |
| 364 | |
| 365 | while (EHStack.stable_begin() != Old) { |
| 366 | EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin()); |
| 367 | |
| 368 | // As long as Old strictly encloses the scope's enclosing normal |
| 369 | // cleanup, we're going to emit another normal cleanup which |
| 370 | // fallthrough can propagate through. |
| 371 | bool FallThroughIsBranchThrough = |
| 372 | Old.strictlyEncloses(Scope.getEnclosingNormalCleanup()); |
| 373 | |
| 374 | PopCleanupBlock(FallThroughIsBranchThrough); |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF, |
| 379 | EHCleanupScope &Scope) { |
| 380 | assert(Scope.isNormalCleanup()); |
| 381 | llvm::BasicBlock *Entry = Scope.getNormalBlock(); |
| 382 | if (!Entry) { |
| 383 | Entry = CGF.createBasicBlock("cleanup"); |
| 384 | Scope.setNormalBlock(Entry); |
| 385 | } |
| 386 | return Entry; |
| 387 | } |
| 388 | |
| 389 | static llvm::BasicBlock *CreateEHEntry(CodeGenFunction &CGF, |
| 390 | EHCleanupScope &Scope) { |
| 391 | assert(Scope.isEHCleanup()); |
| 392 | llvm::BasicBlock *Entry = Scope.getEHBlock(); |
| 393 | if (!Entry) { |
| 394 | Entry = CGF.createBasicBlock("eh.cleanup"); |
| 395 | Scope.setEHBlock(Entry); |
| 396 | } |
| 397 | return Entry; |
| 398 | } |
| 399 | |
| 400 | /// Attempts to reduce a cleanup's entry block to a fallthrough. This |
| 401 | /// is basically llvm::MergeBlockIntoPredecessor, except |
| 402 | /// simplified/optimized for the tighter constraints on cleanup blocks. |
| 403 | /// |
| 404 | /// Returns the new block, whatever it is. |
| 405 | static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF, |
| 406 | llvm::BasicBlock *Entry) { |
| 407 | llvm::BasicBlock *Pred = Entry->getSinglePredecessor(); |
| 408 | if (!Pred) return Entry; |
| 409 | |
| 410 | llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator()); |
| 411 | if (!Br || Br->isConditional()) return Entry; |
| 412 | assert(Br->getSuccessor(0) == Entry); |
| 413 | |
| 414 | // If we were previously inserting at the end of the cleanup entry |
| 415 | // block, we'll need to continue inserting at the end of the |
| 416 | // predecessor. |
| 417 | bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry; |
| 418 | assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end()); |
| 419 | |
| 420 | // Kill the branch. |
| 421 | Br->eraseFromParent(); |
| 422 | |
| 423 | // Merge the blocks. |
| 424 | Pred->getInstList().splice(Pred->end(), Entry->getInstList()); |
| 425 | |
| 426 | // Replace all uses of the entry with the predecessor, in case there |
| 427 | // are phis in the cleanup. |
| 428 | Entry->replaceAllUsesWith(Pred); |
| 429 | |
| 430 | // Kill the entry block. |
| 431 | Entry->eraseFromParent(); |
| 432 | |
| 433 | if (WasInsertBlock) |
| 434 | CGF.Builder.SetInsertPoint(Pred); |
| 435 | |
| 436 | return Pred; |
| 437 | } |
| 438 | |
| 439 | static void EmitCleanup(CodeGenFunction &CGF, |
| 440 | EHScopeStack::Cleanup *Fn, |
| 441 | bool ForEH, |
| 442 | llvm::Value *ActiveFlag) { |
| 443 | // EH cleanups always occur within a terminate scope. |
| 444 | if (ForEH) CGF.EHStack.pushTerminate(); |
| 445 | |
| 446 | // If there's an active flag, load it and skip the cleanup if it's |
| 447 | // false. |
| 448 | llvm::BasicBlock *ContBB = 0; |
| 449 | if (ActiveFlag) { |
| 450 | ContBB = CGF.createBasicBlock("cleanup.done"); |
| 451 | llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action"); |
| 452 | llvm::Value *IsActive |
| 453 | = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active"); |
| 454 | CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB); |
| 455 | CGF.EmitBlock(CleanupBB); |
| 456 | } |
| 457 | |
| 458 | // Ask the cleanup to emit itself. |
| 459 | Fn->Emit(CGF, ForEH); |
| 460 | assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?"); |
| 461 | |
| 462 | // Emit the continuation block if there was an active flag. |
| 463 | if (ActiveFlag) |
| 464 | CGF.EmitBlock(ContBB); |
| 465 | |
| 466 | // Leave the terminate scope. |
| 467 | if (ForEH) CGF.EHStack.popTerminate(); |
| 468 | } |
| 469 | |
| 470 | static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit, |
| 471 | llvm::BasicBlock *From, |
| 472 | llvm::BasicBlock *To) { |
| 473 | // Exit is the exit block of a cleanup, so it always terminates in |
| 474 | // an unconditional branch or a switch. |
| 475 | llvm::TerminatorInst *Term = Exit->getTerminator(); |
| 476 | |
| 477 | if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) { |
| 478 | assert(Br->isUnconditional() && Br->getSuccessor(0) == From); |
| 479 | Br->setSuccessor(0, To); |
| 480 | } else { |
| 481 | llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term); |
| 482 | for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I) |
| 483 | if (Switch->getSuccessor(I) == From) |
| 484 | Switch->setSuccessor(I, To); |
| 485 | } |
| 486 | } |
| 487 | |
| 488 | /// Pops a cleanup block. If the block includes a normal cleanup, the |
| 489 | /// current insertion point is threaded through the cleanup, as are |
| 490 | /// any branch fixups on the cleanup. |
| 491 | void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) { |
| 492 | assert(!EHStack.empty() && "cleanup stack is empty!"); |
| 493 | assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!"); |
| 494 | EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin()); |
| 495 | assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups()); |
| 496 | |
| 497 | // Remember activation information. |
| 498 | bool IsActive = Scope.isActive(); |
| 499 | llvm::Value *NormalActiveFlag = |
| 500 | Scope.shouldTestFlagInNormalCleanup() ? Scope.getActiveFlag() : 0; |
| 501 | llvm::Value *EHActiveFlag = |
| 502 | Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag() : 0; |
| 503 | |
| 504 | // Check whether we need an EH cleanup. This is only true if we've |
| 505 | // generated a lazy EH cleanup block. |
| 506 | bool RequiresEHCleanup = Scope.hasEHBranches(); |
| 507 | |
| 508 | // Check the three conditions which might require a normal cleanup: |
| 509 | |
| 510 | // - whether there are branch fix-ups through this cleanup |
| 511 | unsigned FixupDepth = Scope.getFixupDepth(); |
| 512 | bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth; |
| 513 | |
| 514 | // - whether there are branch-throughs or branch-afters |
| 515 | bool HasExistingBranches = Scope.hasBranches(); |
| 516 | |
| 517 | // - whether there's a fallthrough |
| 518 | llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock(); |
| 519 | bool HasFallthrough = (FallthroughSource != 0 && IsActive); |
| 520 | |
| 521 | // Branch-through fall-throughs leave the insertion point set to the |
| 522 | // end of the last cleanup, which points to the current scope. The |
| 523 | // rest of IR gen doesn't need to worry about this; it only happens |
| 524 | // during the execution of PopCleanupBlocks(). |
| 525 | bool HasPrebranchedFallthrough = |
| 526 | (FallthroughSource && FallthroughSource->getTerminator()); |
| 527 | |
| 528 | // If this is a normal cleanup, then having a prebranched |
| 529 | // fallthrough implies that the fallthrough source unconditionally |
| 530 | // jumps here. |
| 531 | assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough || |
| 532 | (Scope.getNormalBlock() && |
| 533 | FallthroughSource->getTerminator()->getSuccessor(0) |
| 534 | == Scope.getNormalBlock())); |
| 535 | |
| 536 | bool RequiresNormalCleanup = false; |
| 537 | if (Scope.isNormalCleanup() && |
| 538 | (HasFixups || HasExistingBranches || HasFallthrough)) { |
| 539 | RequiresNormalCleanup = true; |
| 540 | } |
| 541 | |
| 542 | // Even if we don't need the normal cleanup, we might still have |
| 543 | // prebranched fallthrough to worry about. |
| 544 | if (Scope.isNormalCleanup() && !RequiresNormalCleanup && |
| 545 | HasPrebranchedFallthrough) { |
| 546 | assert(!IsActive); |
| 547 | |
| 548 | llvm::BasicBlock *NormalEntry = Scope.getNormalBlock(); |
| 549 | |
| 550 | // If we're branching through this cleanup, just forward the |
| 551 | // prebranched fallthrough to the next cleanup, leaving the insert |
| 552 | // point in the old block. |
| 553 | if (FallthroughIsBranchThrough) { |
| 554 | EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup()); |
| 555 | llvm::BasicBlock *EnclosingEntry = |
| 556 | CreateNormalEntry(*this, cast<EHCleanupScope>(S)); |
| 557 | |
| 558 | ForwardPrebranchedFallthrough(FallthroughSource, |
| 559 | NormalEntry, EnclosingEntry); |
| 560 | assert(NormalEntry->use_empty() && |
| 561 | "uses of entry remain after forwarding?"); |
| 562 | delete NormalEntry; |
| 563 | |
| 564 | // Otherwise, we're branching out; just emit the next block. |
| 565 | } else { |
| 566 | EmitBlock(NormalEntry); |
| 567 | SimplifyCleanupEntry(*this, NormalEntry); |
| 568 | } |
| 569 | } |
| 570 | |
| 571 | // If we don't need the cleanup at all, we're done. |
| 572 | if (!RequiresNormalCleanup && !RequiresEHCleanup) { |
| 573 | EHStack.popCleanup(); // safe because there are no fixups |
| 574 | assert(EHStack.getNumBranchFixups() == 0 || |
| 575 | EHStack.hasNormalCleanups()); |
| 576 | return; |
| 577 | } |
| 578 | |
| 579 | // Copy the cleanup emission data out. Note that SmallVector |
| 580 | // guarantees maximal alignment for its buffer regardless of its |
| 581 | // type parameter. |
| 582 | llvm::SmallVector<char, 8*sizeof(void*)> CleanupBuffer; |
| 583 | CleanupBuffer.reserve(Scope.getCleanupSize()); |
| 584 | memcpy(CleanupBuffer.data(), |
| 585 | Scope.getCleanupBuffer(), Scope.getCleanupSize()); |
| 586 | CleanupBuffer.set_size(Scope.getCleanupSize()); |
| 587 | EHScopeStack::Cleanup *Fn = |
| 588 | reinterpret_cast<EHScopeStack::Cleanup*>(CleanupBuffer.data()); |
| 589 | |
| 590 | // We want to emit the EH cleanup after the normal cleanup, but go |
| 591 | // ahead and do the setup for the EH cleanup while the scope is still |
| 592 | // alive. |
| 593 | llvm::BasicBlock *EHEntry = 0; |
| 594 | llvm::SmallVector<llvm::Instruction*, 2> EHInstsToAppend; |
| 595 | if (RequiresEHCleanup) { |
| 596 | EHEntry = CreateEHEntry(*this, Scope); |
| 597 | |
| 598 | // Figure out the branch-through dest if necessary. |
| 599 | llvm::BasicBlock *EHBranchThroughDest = 0; |
| 600 | if (Scope.hasEHBranchThroughs()) { |
| 601 | assert(Scope.getEnclosingEHCleanup() != EHStack.stable_end()); |
| 602 | EHScope &S = *EHStack.find(Scope.getEnclosingEHCleanup()); |
| 603 | EHBranchThroughDest = CreateEHEntry(*this, cast<EHCleanupScope>(S)); |
| 604 | } |
| 605 | |
| 606 | // If we have exactly one branch-after and no branch-throughs, we |
| 607 | // can dispatch it without a switch. |
| 608 | if (!Scope.hasEHBranchThroughs() && |
| 609 | Scope.getNumEHBranchAfters() == 1) { |
| 610 | assert(!EHBranchThroughDest); |
| 611 | |
| 612 | // TODO: remove the spurious eh.cleanup.dest stores if this edge |
| 613 | // never went through any switches. |
| 614 | llvm::BasicBlock *BranchAfterDest = Scope.getEHBranchAfterBlock(0); |
| 615 | EHInstsToAppend.push_back(llvm::BranchInst::Create(BranchAfterDest)); |
| 616 | |
| 617 | // Otherwise, if we have any branch-afters, we need a switch. |
| 618 | } else if (Scope.getNumEHBranchAfters()) { |
| 619 | // The default of the switch belongs to the branch-throughs if |
| 620 | // they exist. |
| 621 | llvm::BasicBlock *Default = |
| 622 | (EHBranchThroughDest ? EHBranchThroughDest : getUnreachableBlock()); |
| 623 | |
| 624 | const unsigned SwitchCapacity = Scope.getNumEHBranchAfters(); |
| 625 | |
| 626 | llvm::LoadInst *Load = |
| 627 | new llvm::LoadInst(getEHCleanupDestSlot(), "cleanup.dest"); |
| 628 | llvm::SwitchInst *Switch = |
| 629 | llvm::SwitchInst::Create(Load, Default, SwitchCapacity); |
| 630 | |
| 631 | EHInstsToAppend.push_back(Load); |
| 632 | EHInstsToAppend.push_back(Switch); |
| 633 | |
| 634 | for (unsigned I = 0, E = Scope.getNumEHBranchAfters(); I != E; ++I) |
| 635 | Switch->addCase(Scope.getEHBranchAfterIndex(I), |
| 636 | Scope.getEHBranchAfterBlock(I)); |
| 637 | |
| 638 | // Otherwise, we have only branch-throughs; jump to the next EH |
| 639 | // cleanup. |
| 640 | } else { |
| 641 | assert(EHBranchThroughDest); |
| 642 | EHInstsToAppend.push_back(llvm::BranchInst::Create(EHBranchThroughDest)); |
| 643 | } |
| 644 | } |
| 645 | |
| 646 | if (!RequiresNormalCleanup) { |
| 647 | EHStack.popCleanup(); |
| 648 | } else { |
| 649 | // If we have a fallthrough and no other need for the cleanup, |
| 650 | // emit it directly. |
| 651 | if (HasFallthrough && !HasPrebranchedFallthrough && |
| 652 | !HasFixups && !HasExistingBranches) { |
| 653 | |
| 654 | // Fixups can cause us to optimistically create a normal block, |
| 655 | // only to later have no real uses for it. Just delete it in |
| 656 | // this case. |
| 657 | // TODO: we can potentially simplify all the uses after this. |
| 658 | if (Scope.getNormalBlock()) { |
| 659 | Scope.getNormalBlock()->replaceAllUsesWith(getUnreachableBlock()); |
| 660 | delete Scope.getNormalBlock(); |
| 661 | } |
| 662 | |
| 663 | EHStack.popCleanup(); |
| 664 | |
| 665 | EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag); |
| 666 | |
| 667 | // Otherwise, the best approach is to thread everything through |
| 668 | // the cleanup block and then try to clean up after ourselves. |
| 669 | } else { |
| 670 | // Force the entry block to exist. |
| 671 | llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope); |
| 672 | |
| 673 | // I. Set up the fallthrough edge in. |
| 674 | |
| 675 | // If there's a fallthrough, we need to store the cleanup |
| 676 | // destination index. For fall-throughs this is always zero. |
| 677 | if (HasFallthrough) { |
| 678 | if (!HasPrebranchedFallthrough) |
| 679 | Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot()); |
| 680 | |
| 681 | // Otherwise, clear the IP if we don't have fallthrough because |
| 682 | // the cleanup is inactive. We don't need to save it because |
| 683 | // it's still just FallthroughSource. |
| 684 | } else if (FallthroughSource) { |
| 685 | assert(!IsActive && "source without fallthrough for active cleanup"); |
| 686 | Builder.ClearInsertionPoint(); |
| 687 | } |
| 688 | |
| 689 | // II. Emit the entry block. This implicitly branches to it if |
| 690 | // we have fallthrough. All the fixups and existing branches |
| 691 | // should already be branched to it. |
| 692 | EmitBlock(NormalEntry); |
| 693 | |
| 694 | // III. Figure out where we're going and build the cleanup |
| 695 | // epilogue. |
| 696 | |
| 697 | bool HasEnclosingCleanups = |
| 698 | (Scope.getEnclosingNormalCleanup() != EHStack.stable_end()); |
| 699 | |
| 700 | // Compute the branch-through dest if we need it: |
| 701 | // - if there are branch-throughs threaded through the scope |
| 702 | // - if fall-through is a branch-through |
| 703 | // - if there are fixups that will be optimistically forwarded |
| 704 | // to the enclosing cleanup |
| 705 | llvm::BasicBlock *BranchThroughDest = 0; |
| 706 | if (Scope.hasBranchThroughs() || |
| 707 | (FallthroughSource && FallthroughIsBranchThrough) || |
| 708 | (HasFixups && HasEnclosingCleanups)) { |
| 709 | assert(HasEnclosingCleanups); |
| 710 | EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup()); |
| 711 | BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S)); |
| 712 | } |
| 713 | |
| 714 | llvm::BasicBlock *FallthroughDest = 0; |
| 715 | llvm::SmallVector<llvm::Instruction*, 2> InstsToAppend; |
| 716 | |
| 717 | // If there's exactly one branch-after and no other threads, |
| 718 | // we can route it without a switch. |
| 719 | if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough && |
| 720 | Scope.getNumBranchAfters() == 1) { |
| 721 | assert(!BranchThroughDest || !IsActive); |
| 722 | |
| 723 | // TODO: clean up the possibly dead stores to the cleanup dest slot. |
| 724 | llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0); |
| 725 | InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter)); |
| 726 | |
| 727 | // Build a switch-out if we need it: |
| 728 | // - if there are branch-afters threaded through the scope |
| 729 | // - if fall-through is a branch-after |
| 730 | // - if there are fixups that have nowhere left to go and |
| 731 | // so must be immediately resolved |
| 732 | } else if (Scope.getNumBranchAfters() || |
| 733 | (HasFallthrough && !FallthroughIsBranchThrough) || |
| 734 | (HasFixups && !HasEnclosingCleanups)) { |
| 735 | |
| 736 | llvm::BasicBlock *Default = |
| 737 | (BranchThroughDest ? BranchThroughDest : getUnreachableBlock()); |
| 738 | |
| 739 | // TODO: base this on the number of branch-afters and fixups |
| 740 | const unsigned SwitchCapacity = 10; |
| 741 | |
| 742 | llvm::LoadInst *Load = |
| 743 | new llvm::LoadInst(getNormalCleanupDestSlot(), "cleanup.dest"); |
| 744 | llvm::SwitchInst *Switch = |
| 745 | llvm::SwitchInst::Create(Load, Default, SwitchCapacity); |
| 746 | |
| 747 | InstsToAppend.push_back(Load); |
| 748 | InstsToAppend.push_back(Switch); |
| 749 | |
| 750 | // Branch-after fallthrough. |
| 751 | if (FallthroughSource && !FallthroughIsBranchThrough) { |
| 752 | FallthroughDest = createBasicBlock("cleanup.cont"); |
| 753 | if (HasFallthrough) |
| 754 | Switch->addCase(Builder.getInt32(0), FallthroughDest); |
| 755 | } |
| 756 | |
| 757 | for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) { |
| 758 | Switch->addCase(Scope.getBranchAfterIndex(I), |
| 759 | Scope.getBranchAfterBlock(I)); |
| 760 | } |
| 761 | |
| 762 | // If there aren't any enclosing cleanups, we can resolve all |
| 763 | // the fixups now. |
| 764 | if (HasFixups && !HasEnclosingCleanups) |
| 765 | ResolveAllBranchFixups(*this, Switch, NormalEntry); |
| 766 | } else { |
| 767 | // We should always have a branch-through destination in this case. |
| 768 | assert(BranchThroughDest); |
| 769 | InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest)); |
| 770 | } |
| 771 | |
| 772 | // IV. Pop the cleanup and emit it. |
| 773 | EHStack.popCleanup(); |
| 774 | assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups); |
| 775 | |
| 776 | EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag); |
| 777 | |
| 778 | // Append the prepared cleanup prologue from above. |
| 779 | llvm::BasicBlock *NormalExit = Builder.GetInsertBlock(); |
| 780 | for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I) |
| 781 | NormalExit->getInstList().push_back(InstsToAppend[I]); |
| 782 | |
| 783 | // Optimistically hope that any fixups will continue falling through. |
| 784 | for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups(); |
| 785 | I < E; ++I) { |
John McCall | d16c2cf | 2011-02-08 08:22:06 +0000 | [diff] [blame] | 786 | BranchFixup &Fixup = EHStack.getBranchFixup(I); |
John McCall | 36f893c | 2011-01-28 11:13:47 +0000 | [diff] [blame] | 787 | if (!Fixup.Destination) continue; |
| 788 | if (!Fixup.OptimisticBranchBlock) { |
| 789 | new llvm::StoreInst(Builder.getInt32(Fixup.DestinationIndex), |
| 790 | getNormalCleanupDestSlot(), |
| 791 | Fixup.InitialBranch); |
| 792 | Fixup.InitialBranch->setSuccessor(0, NormalEntry); |
| 793 | } |
| 794 | Fixup.OptimisticBranchBlock = NormalExit; |
| 795 | } |
| 796 | |
| 797 | // V. Set up the fallthrough edge out. |
| 798 | |
| 799 | // Case 1: a fallthrough source exists but shouldn't branch to |
| 800 | // the cleanup because the cleanup is inactive. |
| 801 | if (!HasFallthrough && FallthroughSource) { |
| 802 | assert(!IsActive); |
| 803 | |
| 804 | // If we have a prebranched fallthrough, that needs to be |
| 805 | // forwarded to the right block. |
| 806 | if (HasPrebranchedFallthrough) { |
| 807 | llvm::BasicBlock *Next; |
| 808 | if (FallthroughIsBranchThrough) { |
| 809 | Next = BranchThroughDest; |
| 810 | assert(!FallthroughDest); |
| 811 | } else { |
| 812 | Next = FallthroughDest; |
| 813 | } |
| 814 | |
| 815 | ForwardPrebranchedFallthrough(FallthroughSource, NormalEntry, Next); |
| 816 | } |
| 817 | Builder.SetInsertPoint(FallthroughSource); |
| 818 | |
| 819 | // Case 2: a fallthrough source exists and should branch to the |
| 820 | // cleanup, but we're not supposed to branch through to the next |
| 821 | // cleanup. |
| 822 | } else if (HasFallthrough && FallthroughDest) { |
| 823 | assert(!FallthroughIsBranchThrough); |
| 824 | EmitBlock(FallthroughDest); |
| 825 | |
| 826 | // Case 3: a fallthrough source exists and should branch to the |
| 827 | // cleanup and then through to the next. |
| 828 | } else if (HasFallthrough) { |
| 829 | // Everything is already set up for this. |
| 830 | |
| 831 | // Case 4: no fallthrough source exists. |
| 832 | } else { |
| 833 | Builder.ClearInsertionPoint(); |
| 834 | } |
| 835 | |
| 836 | // VI. Assorted cleaning. |
| 837 | |
| 838 | // Check whether we can merge NormalEntry into a single predecessor. |
| 839 | // This might invalidate (non-IR) pointers to NormalEntry. |
| 840 | llvm::BasicBlock *NewNormalEntry = |
| 841 | SimplifyCleanupEntry(*this, NormalEntry); |
| 842 | |
| 843 | // If it did invalidate those pointers, and NormalEntry was the same |
| 844 | // as NormalExit, go back and patch up the fixups. |
| 845 | if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit) |
| 846 | for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups(); |
| 847 | I < E; ++I) |
John McCall | d16c2cf | 2011-02-08 08:22:06 +0000 | [diff] [blame] | 848 | EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry; |
John McCall | 36f893c | 2011-01-28 11:13:47 +0000 | [diff] [blame] | 849 | } |
| 850 | } |
| 851 | |
| 852 | assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0); |
| 853 | |
| 854 | // Emit the EH cleanup if required. |
| 855 | if (RequiresEHCleanup) { |
| 856 | CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP(); |
| 857 | |
| 858 | EmitBlock(EHEntry); |
| 859 | EmitCleanup(*this, Fn, /*ForEH*/ true, EHActiveFlag); |
| 860 | |
| 861 | // Append the prepared cleanup prologue from above. |
| 862 | llvm::BasicBlock *EHExit = Builder.GetInsertBlock(); |
| 863 | for (unsigned I = 0, E = EHInstsToAppend.size(); I != E; ++I) |
| 864 | EHExit->getInstList().push_back(EHInstsToAppend[I]); |
| 865 | |
| 866 | Builder.restoreIP(SavedIP); |
| 867 | |
| 868 | SimplifyCleanupEntry(*this, EHEntry); |
| 869 | } |
| 870 | } |
| 871 | |
Chris Lattner | b11f919 | 2011-04-17 00:54:30 +0000 | [diff] [blame] | 872 | /// isObviouslyBranchWithoutCleanups - Return true if a branch to the |
| 873 | /// specified destination obviously has no cleanups to run. 'false' is always |
| 874 | /// a conservatively correct answer for this method. |
| 875 | bool CodeGenFunction::isObviouslyBranchWithoutCleanups(JumpDest Dest) const { |
| 876 | assert(Dest.getScopeDepth().encloses(EHStack.stable_begin()) |
| 877 | && "stale jump destination"); |
| 878 | |
| 879 | // Calculate the innermost active normal cleanup. |
| 880 | EHScopeStack::stable_iterator TopCleanup = |
| 881 | EHStack.getInnermostActiveNormalCleanup(); |
| 882 | |
| 883 | // If we're not in an active normal cleanup scope, or if the |
| 884 | // destination scope is within the innermost active normal cleanup |
| 885 | // scope, we don't need to worry about fixups. |
| 886 | if (TopCleanup == EHStack.stable_end() || |
| 887 | TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid |
| 888 | return true; |
| 889 | |
| 890 | // Otherwise, we might need some cleanups. |
| 891 | return false; |
| 892 | } |
| 893 | |
| 894 | |
John McCall | 36f893c | 2011-01-28 11:13:47 +0000 | [diff] [blame] | 895 | /// Terminate the current block by emitting a branch which might leave |
| 896 | /// the current cleanup-protected scope. The target scope may not yet |
| 897 | /// be known, in which case this will require a fixup. |
| 898 | /// |
| 899 | /// As a side-effect, this method clears the insertion point. |
| 900 | void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) { |
John McCall | 27f8d70 | 2011-02-25 04:19:13 +0000 | [diff] [blame] | 901 | assert(Dest.getScopeDepth().encloses(EHStack.stable_begin()) |
John McCall | 36f893c | 2011-01-28 11:13:47 +0000 | [diff] [blame] | 902 | && "stale jump destination"); |
| 903 | |
| 904 | if (!HaveInsertPoint()) |
| 905 | return; |
| 906 | |
| 907 | // Create the branch. |
| 908 | llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock()); |
| 909 | |
| 910 | // Calculate the innermost active normal cleanup. |
| 911 | EHScopeStack::stable_iterator |
| 912 | TopCleanup = EHStack.getInnermostActiveNormalCleanup(); |
| 913 | |
| 914 | // If we're not in an active normal cleanup scope, or if the |
| 915 | // destination scope is within the innermost active normal cleanup |
| 916 | // scope, we don't need to worry about fixups. |
| 917 | if (TopCleanup == EHStack.stable_end() || |
| 918 | TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid |
| 919 | Builder.ClearInsertionPoint(); |
| 920 | return; |
| 921 | } |
| 922 | |
| 923 | // If we can't resolve the destination cleanup scope, just add this |
| 924 | // to the current cleanup scope as a branch fixup. |
| 925 | if (!Dest.getScopeDepth().isValid()) { |
| 926 | BranchFixup &Fixup = EHStack.addBranchFixup(); |
| 927 | Fixup.Destination = Dest.getBlock(); |
| 928 | Fixup.DestinationIndex = Dest.getDestIndex(); |
| 929 | Fixup.InitialBranch = BI; |
| 930 | Fixup.OptimisticBranchBlock = 0; |
| 931 | |
| 932 | Builder.ClearInsertionPoint(); |
| 933 | return; |
| 934 | } |
| 935 | |
| 936 | // Otherwise, thread through all the normal cleanups in scope. |
| 937 | |
| 938 | // Store the index at the start. |
| 939 | llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex()); |
| 940 | new llvm::StoreInst(Index, getNormalCleanupDestSlot(), BI); |
| 941 | |
| 942 | // Adjust BI to point to the first cleanup block. |
| 943 | { |
| 944 | EHCleanupScope &Scope = |
| 945 | cast<EHCleanupScope>(*EHStack.find(TopCleanup)); |
| 946 | BI->setSuccessor(0, CreateNormalEntry(*this, Scope)); |
| 947 | } |
| 948 | |
| 949 | // Add this destination to all the scopes involved. |
| 950 | EHScopeStack::stable_iterator I = TopCleanup; |
| 951 | EHScopeStack::stable_iterator E = Dest.getScopeDepth(); |
| 952 | if (E.strictlyEncloses(I)) { |
| 953 | while (true) { |
| 954 | EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I)); |
| 955 | assert(Scope.isNormalCleanup()); |
| 956 | I = Scope.getEnclosingNormalCleanup(); |
| 957 | |
| 958 | // If this is the last cleanup we're propagating through, tell it |
| 959 | // that there's a resolved jump moving through it. |
| 960 | if (!E.strictlyEncloses(I)) { |
| 961 | Scope.addBranchAfter(Index, Dest.getBlock()); |
| 962 | break; |
| 963 | } |
| 964 | |
| 965 | // Otherwise, tell the scope that there's a jump propoagating |
| 966 | // through it. If this isn't new information, all the rest of |
| 967 | // the work has been done before. |
| 968 | if (!Scope.addBranchThrough(Dest.getBlock())) |
| 969 | break; |
| 970 | } |
| 971 | } |
| 972 | |
| 973 | Builder.ClearInsertionPoint(); |
| 974 | } |
| 975 | |
| 976 | void CodeGenFunction::EmitBranchThroughEHCleanup(UnwindDest Dest) { |
| 977 | // We should never get invalid scope depths for an UnwindDest; that |
| 978 | // implies that the destination wasn't set up correctly. |
| 979 | assert(Dest.getScopeDepth().isValid() && "invalid scope depth on EH dest?"); |
| 980 | |
| 981 | if (!HaveInsertPoint()) |
| 982 | return; |
| 983 | |
| 984 | // Create the branch. |
| 985 | llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock()); |
| 986 | |
| 987 | // Calculate the innermost active cleanup. |
| 988 | EHScopeStack::stable_iterator |
| 989 | InnermostCleanup = EHStack.getInnermostActiveEHCleanup(); |
| 990 | |
| 991 | // If the destination is in the same EH cleanup scope as us, we |
| 992 | // don't need to thread through anything. |
| 993 | if (InnermostCleanup.encloses(Dest.getScopeDepth())) { |
| 994 | Builder.ClearInsertionPoint(); |
| 995 | return; |
| 996 | } |
| 997 | assert(InnermostCleanup != EHStack.stable_end()); |
| 998 | |
| 999 | // Store the index at the start. |
| 1000 | llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex()); |
| 1001 | new llvm::StoreInst(Index, getEHCleanupDestSlot(), BI); |
| 1002 | |
| 1003 | // Adjust BI to point to the first cleanup block. |
| 1004 | { |
| 1005 | EHCleanupScope &Scope = |
| 1006 | cast<EHCleanupScope>(*EHStack.find(InnermostCleanup)); |
| 1007 | BI->setSuccessor(0, CreateEHEntry(*this, Scope)); |
| 1008 | } |
| 1009 | |
| 1010 | // Add this destination to all the scopes involved. |
| 1011 | for (EHScopeStack::stable_iterator |
| 1012 | I = InnermostCleanup, E = Dest.getScopeDepth(); ; ) { |
| 1013 | assert(E.strictlyEncloses(I)); |
| 1014 | EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I)); |
| 1015 | assert(Scope.isEHCleanup()); |
| 1016 | I = Scope.getEnclosingEHCleanup(); |
| 1017 | |
| 1018 | // If this is the last cleanup we're propagating through, add this |
| 1019 | // as a branch-after. |
| 1020 | if (I == E) { |
| 1021 | Scope.addEHBranchAfter(Index, Dest.getBlock()); |
| 1022 | break; |
| 1023 | } |
| 1024 | |
| 1025 | // Otherwise, add it as a branch-through. If this isn't new |
| 1026 | // information, all the rest of the work has been done before. |
| 1027 | if (!Scope.addEHBranchThrough(Dest.getBlock())) |
| 1028 | break; |
| 1029 | } |
| 1030 | |
| 1031 | Builder.ClearInsertionPoint(); |
| 1032 | } |
| 1033 | |
| 1034 | static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack, |
| 1035 | EHScopeStack::stable_iterator C) { |
| 1036 | // If we needed a normal block for any reason, that counts. |
| 1037 | if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock()) |
| 1038 | return true; |
| 1039 | |
| 1040 | // Check whether any enclosed cleanups were needed. |
| 1041 | for (EHScopeStack::stable_iterator |
| 1042 | I = EHStack.getInnermostNormalCleanup(); |
| 1043 | I != C; ) { |
| 1044 | assert(C.strictlyEncloses(I)); |
| 1045 | EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I)); |
| 1046 | if (S.getNormalBlock()) return true; |
| 1047 | I = S.getEnclosingNormalCleanup(); |
| 1048 | } |
| 1049 | |
| 1050 | return false; |
| 1051 | } |
| 1052 | |
| 1053 | static bool IsUsedAsEHCleanup(EHScopeStack &EHStack, |
| 1054 | EHScopeStack::stable_iterator C) { |
| 1055 | // If we needed an EH block for any reason, that counts. |
| 1056 | if (cast<EHCleanupScope>(*EHStack.find(C)).getEHBlock()) |
| 1057 | return true; |
| 1058 | |
| 1059 | // Check whether any enclosed cleanups were needed. |
| 1060 | for (EHScopeStack::stable_iterator |
| 1061 | I = EHStack.getInnermostEHCleanup(); I != C; ) { |
| 1062 | assert(C.strictlyEncloses(I)); |
| 1063 | EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I)); |
| 1064 | if (S.getEHBlock()) return true; |
| 1065 | I = S.getEnclosingEHCleanup(); |
| 1066 | } |
| 1067 | |
| 1068 | return false; |
| 1069 | } |
| 1070 | |
| 1071 | enum ForActivation_t { |
| 1072 | ForActivation, |
| 1073 | ForDeactivation |
| 1074 | }; |
| 1075 | |
| 1076 | /// The given cleanup block is changing activation state. Configure a |
| 1077 | /// cleanup variable if necessary. |
| 1078 | /// |
| 1079 | /// It would be good if we had some way of determining if there were |
| 1080 | /// extra uses *after* the change-over point. |
| 1081 | static void SetupCleanupBlockActivation(CodeGenFunction &CGF, |
| 1082 | EHScopeStack::stable_iterator C, |
| 1083 | ForActivation_t Kind) { |
| 1084 | EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C)); |
| 1085 | |
| 1086 | // We always need the flag if we're activating the cleanup, because |
| 1087 | // we have to assume that the current location doesn't necessarily |
| 1088 | // dominate all future uses of the cleanup. |
| 1089 | bool NeedFlag = (Kind == ForActivation); |
| 1090 | |
| 1091 | // Calculate whether the cleanup was used: |
| 1092 | |
| 1093 | // - as a normal cleanup |
| 1094 | if (Scope.isNormalCleanup() && IsUsedAsNormalCleanup(CGF.EHStack, C)) { |
| 1095 | Scope.setTestFlagInNormalCleanup(); |
| 1096 | NeedFlag = true; |
| 1097 | } |
| 1098 | |
| 1099 | // - as an EH cleanup |
| 1100 | if (Scope.isEHCleanup() && IsUsedAsEHCleanup(CGF.EHStack, C)) { |
| 1101 | Scope.setTestFlagInEHCleanup(); |
| 1102 | NeedFlag = true; |
| 1103 | } |
| 1104 | |
| 1105 | // If it hasn't yet been used as either, we're done. |
| 1106 | if (!NeedFlag) return; |
| 1107 | |
| 1108 | llvm::AllocaInst *Var = Scope.getActiveFlag(); |
| 1109 | if (!Var) { |
| 1110 | Var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "cleanup.isactive"); |
| 1111 | Scope.setActiveFlag(Var); |
| 1112 | |
| 1113 | // Initialize to true or false depending on whether it was |
| 1114 | // active up to this point. |
| 1115 | CGF.InitTempAlloca(Var, CGF.Builder.getInt1(Kind == ForDeactivation)); |
| 1116 | } |
| 1117 | |
| 1118 | CGF.Builder.CreateStore(CGF.Builder.getInt1(Kind == ForActivation), Var); |
| 1119 | } |
| 1120 | |
| 1121 | /// Activate a cleanup that was created in an inactivated state. |
| 1122 | void CodeGenFunction::ActivateCleanupBlock(EHScopeStack::stable_iterator C) { |
| 1123 | assert(C != EHStack.stable_end() && "activating bottom of stack?"); |
| 1124 | EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C)); |
| 1125 | assert(!Scope.isActive() && "double activation"); |
| 1126 | |
| 1127 | SetupCleanupBlockActivation(*this, C, ForActivation); |
| 1128 | |
| 1129 | Scope.setActive(true); |
| 1130 | } |
| 1131 | |
| 1132 | /// Deactive a cleanup that was created in an active state. |
| 1133 | void CodeGenFunction::DeactivateCleanupBlock(EHScopeStack::stable_iterator C) { |
| 1134 | assert(C != EHStack.stable_end() && "deactivating bottom of stack?"); |
| 1135 | EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C)); |
| 1136 | assert(Scope.isActive() && "double deactivation"); |
| 1137 | |
| 1138 | // If it's the top of the stack, just pop it. |
| 1139 | if (C == EHStack.stable_begin()) { |
| 1140 | // If it's a normal cleanup, we need to pretend that the |
| 1141 | // fallthrough is unreachable. |
| 1142 | CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP(); |
| 1143 | PopCleanupBlock(); |
| 1144 | Builder.restoreIP(SavedIP); |
| 1145 | return; |
| 1146 | } |
| 1147 | |
| 1148 | // Otherwise, follow the general case. |
| 1149 | SetupCleanupBlockActivation(*this, C, ForDeactivation); |
| 1150 | |
| 1151 | Scope.setActive(false); |
| 1152 | } |
| 1153 | |
| 1154 | llvm::Value *CodeGenFunction::getNormalCleanupDestSlot() { |
| 1155 | if (!NormalCleanupDest) |
| 1156 | NormalCleanupDest = |
| 1157 | CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot"); |
| 1158 | return NormalCleanupDest; |
| 1159 | } |
| 1160 | |
| 1161 | llvm::Value *CodeGenFunction::getEHCleanupDestSlot() { |
| 1162 | if (!EHCleanupDest) |
| 1163 | EHCleanupDest = |
| 1164 | CreateTempAlloca(Builder.getInt32Ty(), "eh.cleanup.dest.slot"); |
| 1165 | return EHCleanupDest; |
| 1166 | } |