CodeGenFunction.cpp revision 3947de5edda7e0c32060c568cc5f7b2aae6f70b4
1//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===// 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 coordinates the per-function state used while generating code. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CodeGenFunction.h" 15#include "CodeGenModule.h" 16#include "CGDebugInfo.h" 17#include "clang/Basic/TargetInfo.h" 18#include "clang/AST/APValue.h" 19#include "clang/AST/ASTContext.h" 20#include "clang/AST/Decl.h" 21#include "llvm/Support/CFG.h" 22#include "llvm/Target/TargetData.h" 23using namespace clang; 24using namespace CodeGen; 25 26CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 27 : BlockFunction(Builder), CGM(cgm), Target(CGM.getContext().Target), 28 DebugInfo(0), SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0) { 29 LLVMIntTy = ConvertType(getContext().IntTy); 30 LLVMPointerWidth = Target.getPointerWidth(0); 31 32 // FIXME: We need to rearrange the code for copy/dispose so we have this 33 // sooner, so we can calculate offsets correctly. 34 BlockHasCopyDispose = false; 35 if (!BlockHasCopyDispose) 36 BlockOffset = CGM.getTargetData() 37 .getTypeStoreSizeInBits(CGM.getGenericBlockLiteralType()) / 8; 38 else 39 BlockOffset = CGM.getTargetData() 40 .getTypeStoreSizeInBits(CGM.getGenericExtendedBlockLiteralType()) / 8; 41 BlockAlign = getContext().getTypeAlign(getContext().VoidPtrTy) / 8; 42} 43 44ASTContext &CodeGenFunction::getContext() const { 45 return CGM.getContext(); 46} 47 48 49llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) { 50 llvm::BasicBlock *&BB = LabelMap[S]; 51 if (BB) return BB; 52 53 // Create, but don't insert, the new block. 54 return BB = createBasicBlock(S->getName()); 55} 56 57llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) { 58 llvm::Value *Res = LocalDeclMap[VD]; 59 assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!"); 60 return Res; 61} 62 63llvm::Constant * 64CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) { 65 return cast<llvm::Constant>(GetAddrOfLocalVar(BVD)); 66} 67 68const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 69 return CGM.getTypes().ConvertTypeForMem(T); 70} 71 72const llvm::Type *CodeGenFunction::ConvertType(QualType T) { 73 return CGM.getTypes().ConvertType(T); 74} 75 76bool CodeGenFunction::hasAggregateLLVMType(QualType T) { 77 // FIXME: Use positive checks instead of negative ones to be more 78 // robust in the face of extension. 79 return !T->hasPointerRepresentation() &&!T->isRealType() && 80 !T->isVoidType() && !T->isVectorType() && !T->isFunctionType() && 81 !T->isBlockPointerType(); 82} 83 84void CodeGenFunction::EmitReturnBlock() { 85 // For cleanliness, we try to avoid emitting the return block for 86 // simple cases. 87 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 88 89 if (CurBB) { 90 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 91 92 // We have a valid insert point, reuse it if there are no explicit 93 // jumps to the return block. 94 if (ReturnBlock->use_empty()) 95 delete ReturnBlock; 96 else 97 EmitBlock(ReturnBlock); 98 return; 99 } 100 101 // Otherwise, if the return block is the target of a single direct 102 // branch then we can just put the code in that block instead. This 103 // cleans up functions which started with a unified return block. 104 if (ReturnBlock->hasOneUse()) { 105 llvm::BranchInst *BI = 106 dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin()); 107 if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) { 108 // Reset insertion point and delete the branch. 109 Builder.SetInsertPoint(BI->getParent()); 110 BI->eraseFromParent(); 111 delete ReturnBlock; 112 return; 113 } 114 } 115 116 // FIXME: We are at an unreachable point, there is no reason to emit 117 // the block unless it has uses. However, we still need a place to 118 // put the debug region.end for now. 119 120 EmitBlock(ReturnBlock); 121} 122 123void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 124 // Finish emission of indirect switches. 125 EmitIndirectSwitches(); 126 127 assert(BreakContinueStack.empty() && 128 "mismatched push/pop in break/continue stack!"); 129 assert(BlockScopes.empty() && 130 "did not remove all blocks from block scope map!"); 131 assert(CleanupEntries.empty() && 132 "mismatched push/pop in cleanup stack!"); 133 134 // Emit function epilog (to return). 135 EmitReturnBlock(); 136 137 // Emit debug descriptor for function end. 138 if (CGDebugInfo *DI = getDebugInfo()) { 139 DI->setLocation(EndLoc); 140 DI->EmitRegionEnd(CurFn, Builder); 141 } 142 143 EmitFunctionEpilog(*CurFnInfo, ReturnValue); 144 145 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 146 AllocaInsertPt->eraseFromParent(); 147 AllocaInsertPt = 0; 148} 149 150void CodeGenFunction::StartFunction(const Decl *D, QualType RetTy, 151 llvm::Function *Fn, 152 const FunctionArgList &Args, 153 SourceLocation StartLoc) { 154 DidCallStackSave = false; 155 CurFuncDecl = D; 156 FnRetTy = RetTy; 157 CurFn = Fn; 158 assert(CurFn->isDeclaration() && "Function already has body?"); 159 160 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 161 162 // Create a marker to make it easy to insert allocas into the entryblock 163 // later. Don't create this with the builder, because we don't want it 164 // folded. 165 llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::Int32Ty); 166 AllocaInsertPt = new llvm::BitCastInst(Undef, llvm::Type::Int32Ty, "allocapt", 167 EntryBB); 168 169 ReturnBlock = createBasicBlock("return"); 170 ReturnValue = 0; 171 if (!RetTy->isVoidType()) 172 ReturnValue = CreateTempAlloca(ConvertType(RetTy), "retval"); 173 174 Builder.SetInsertPoint(EntryBB); 175 176 // Emit subprogram debug descriptor. 177 // FIXME: The cast here is a huge hack. 178 if (CGDebugInfo *DI = getDebugInfo()) { 179 DI->setLocation(StartLoc); 180 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 181 DI->EmitFunctionStart(CGM.getMangledName(FD), RetTy, CurFn, Builder); 182 } else { 183 // Just use LLVM function name. 184 DI->EmitFunctionStart(Fn->getName().c_str(), 185 RetTy, CurFn, Builder); 186 } 187 } 188 189 // FIXME: Leaked. 190 CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args); 191 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 192 193 // If any of the arguments have a variably modified type, make sure to 194 // emit the type size. 195 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 196 i != e; ++i) { 197 QualType Ty = i->second; 198 199 if (Ty->isVariablyModifiedType()) 200 EmitVLASize(Ty); 201 } 202} 203 204void CodeGenFunction::GenerateCode(const FunctionDecl *FD, 205 llvm::Function *Fn) { 206 // Check if we should generate debug info for this function. 207 if (CGM.getDebugInfo() && !FD->getAttr<NodebugAttr>()) 208 DebugInfo = CGM.getDebugInfo(); 209 210 FunctionArgList Args; 211 if (FD->getNumParams()) { 212 const FunctionProtoType* FProto = FD->getType()->getAsFunctionProtoType(); 213 assert(FProto && "Function def must have prototype!"); 214 215 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 216 Args.push_back(std::make_pair(FD->getParamDecl(i), 217 FProto->getArgType(i))); 218 } 219 220 StartFunction(FD, FD->getResultType(), Fn, Args, 221 cast<CompoundStmt>(FD->getBody())->getLBracLoc()); 222 223 EmitStmt(FD->getBody()); 224 225 const CompoundStmt *S = dyn_cast<CompoundStmt>(FD->getBody()); 226 if (S) { 227 FinishFunction(S->getRBracLoc()); 228 } else { 229 FinishFunction(); 230 } 231} 232 233/// ContainsLabel - Return true if the statement contains a label in it. If 234/// this statement is not executed normally, it not containing a label means 235/// that we can just remove the code. 236bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 237 // Null statement, not a label! 238 if (S == 0) return false; 239 240 // If this is a label, we have to emit the code, consider something like: 241 // if (0) { ... foo: bar(); } goto foo; 242 if (isa<LabelStmt>(S)) 243 return true; 244 245 // If this is a case/default statement, and we haven't seen a switch, we have 246 // to emit the code. 247 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 248 return true; 249 250 // If this is a switch statement, we want to ignore cases below it. 251 if (isa<SwitchStmt>(S)) 252 IgnoreCaseStmts = true; 253 254 // Scan subexpressions for verboten labels. 255 for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 256 I != E; ++I) 257 if (ContainsLabel(*I, IgnoreCaseStmts)) 258 return true; 259 260 return false; 261} 262 263 264/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to 265/// a constant, or if it does but contains a label, return 0. If it constant 266/// folds to 'true' and does not contain a label, return 1, if it constant folds 267/// to 'false' and does not contain a label, return -1. 268int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { 269 // FIXME: Rename and handle conversion of other evaluatable things 270 // to bool. 271 Expr::EvalResult Result; 272 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 273 Result.HasSideEffects) 274 return 0; // Not foldable, not integer or not fully evaluatable. 275 276 if (CodeGenFunction::ContainsLabel(Cond)) 277 return 0; // Contains a label. 278 279 return Result.Val.getInt().getBoolValue() ? 1 : -1; 280} 281 282 283/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 284/// statement) to the specified blocks. Based on the condition, this might try 285/// to simplify the codegen of the conditional based on the branch. 286/// 287void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 288 llvm::BasicBlock *TrueBlock, 289 llvm::BasicBlock *FalseBlock) { 290 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) 291 return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); 292 293 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 294 // Handle X && Y in a condition. 295 if (CondBOp->getOpcode() == BinaryOperator::LAnd) { 296 // If we have "1 && X", simplify the code. "0 && X" would have constant 297 // folded if the case was simple enough. 298 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { 299 // br(1 && X) -> br(X). 300 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 301 } 302 303 // If we have "X && 1", simplify the code to use an uncond branch. 304 // "X && 0" would have been constant folded to 0. 305 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) { 306 // br(X && 1) -> br(X). 307 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 308 } 309 310 // Emit the LHS as a conditional. If the LHS conditional is false, we 311 // want to jump to the FalseBlock. 312 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 313 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 314 EmitBlock(LHSTrue); 315 316 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 317 return; 318 } else if (CondBOp->getOpcode() == BinaryOperator::LOr) { 319 // If we have "0 || X", simplify the code. "1 || X" would have constant 320 // folded if the case was simple enough. 321 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { 322 // br(0 || X) -> br(X). 323 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 324 } 325 326 // If we have "X || 0", simplify the code to use an uncond branch. 327 // "X || 1" would have been constant folded to 1. 328 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) { 329 // br(X || 0) -> br(X). 330 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 331 } 332 333 // Emit the LHS as a conditional. If the LHS conditional is true, we 334 // want to jump to the TrueBlock. 335 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 336 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 337 EmitBlock(LHSFalse); 338 339 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 340 return; 341 } 342 } 343 344 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 345 // br(!x, t, f) -> br(x, f, t) 346 if (CondUOp->getOpcode() == UnaryOperator::LNot) 347 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 348 } 349 350 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 351 // Handle ?: operator. 352 353 // Just ignore GNU ?: extension. 354 if (CondOp->getLHS()) { 355 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 356 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 357 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 358 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 359 EmitBlock(LHSBlock); 360 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 361 EmitBlock(RHSBlock); 362 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 363 return; 364 } 365 } 366 367 // Emit the code with the fully general case. 368 llvm::Value *CondV = EvaluateExprAsBool(Cond); 369 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 370} 371 372/// getCGRecordLayout - Return record layout info. 373const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT, 374 QualType Ty) { 375 const RecordType *RTy = Ty->getAsRecordType(); 376 assert (RTy && "Unexpected type. RecordType expected here."); 377 378 return CGT.getCGRecordLayout(RTy->getDecl()); 379} 380 381/// ErrorUnsupported - Print out an error that codegen doesn't support the 382/// specified stmt yet. 383void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 384 bool OmitOnError) { 385 CGM.ErrorUnsupported(S, Type, OmitOnError); 386} 387 388unsigned CodeGenFunction::GetIDForAddrOfLabel(const LabelStmt *L) { 389 // Use LabelIDs.size() as the new ID if one hasn't been assigned. 390 return LabelIDs.insert(std::make_pair(L, LabelIDs.size())).first->second; 391} 392 393void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) 394{ 395 const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 396 if (DestPtr->getType() != BP) 397 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 398 399 // Get size and alignment info for this aggregate. 400 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 401 402 // FIXME: Handle variable sized types. 403 const llvm::Type *IntPtr = llvm::IntegerType::get(LLVMPointerWidth); 404 405 Builder.CreateCall4(CGM.getMemSetFn(), DestPtr, 406 llvm::ConstantInt::getNullValue(llvm::Type::Int8Ty), 407 // TypeInfo.first describes size in bits. 408 llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), 409 llvm::ConstantInt::get(llvm::Type::Int32Ty, 410 TypeInfo.second/8)); 411} 412 413void CodeGenFunction::EmitIndirectSwitches() { 414 llvm::BasicBlock *Default; 415 416 if (IndirectSwitches.empty()) 417 return; 418 419 if (!LabelIDs.empty()) { 420 Default = getBasicBlockForLabel(LabelIDs.begin()->first); 421 } else { 422 // No possible targets for indirect goto, just emit an infinite 423 // loop. 424 Default = createBasicBlock("indirectgoto.loop", CurFn); 425 llvm::BranchInst::Create(Default, Default); 426 } 427 428 for (std::vector<llvm::SwitchInst*>::iterator i = IndirectSwitches.begin(), 429 e = IndirectSwitches.end(); i != e; ++i) { 430 llvm::SwitchInst *I = *i; 431 432 I->setSuccessor(0, Default); 433 for (std::map<const LabelStmt*,unsigned>::iterator LI = LabelIDs.begin(), 434 LE = LabelIDs.end(); LI != LE; ++LI) { 435 I->addCase(llvm::ConstantInt::get(llvm::Type::Int32Ty, 436 LI->second), 437 getBasicBlockForLabel(LI->first)); 438 } 439 } 440} 441 442llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) 443{ 444 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 445 446 assert(SizeEntry && "Did not emit size for type"); 447 return SizeEntry; 448} 449 450llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) 451{ 452 assert(Ty->isVariablyModifiedType() && 453 "Must pass variably modified type to EmitVLASizes!"); 454 455 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 456 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 457 458 if (!SizeEntry) { 459 // Get the element size; 460 llvm::Value *ElemSize; 461 462 QualType ElemTy = VAT->getElementType(); 463 464 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 465 466 if (ElemTy->isVariableArrayType()) 467 ElemSize = EmitVLASize(ElemTy); 468 else { 469 ElemSize = llvm::ConstantInt::get(SizeTy, 470 getContext().getTypeSize(ElemTy) / 8); 471 } 472 473 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 474 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 475 476 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 477 } 478 479 return SizeEntry; 480 } else if (const PointerType *PT = Ty->getAsPointerType()) 481 EmitVLASize(PT->getPointeeType()); 482 else { 483 assert(0 && "unknown VM type!"); 484 } 485 486 return 0; 487} 488 489llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 490 if (CGM.getContext().getBuiltinVaListType()->isArrayType()) { 491 return EmitScalarExpr(E); 492 } 493 return EmitLValue(E).getAddress(); 494} 495 496void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupBlock) 497{ 498 CleanupEntries.push_back(CleanupEntry(CleanupBlock)); 499} 500 501void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) 502{ 503 assert(CleanupEntries.size() >= OldCleanupStackSize && 504 "Cleanup stack mismatch!"); 505 506 while (CleanupEntries.size() > OldCleanupStackSize) 507 EmitCleanupBlock(); 508} 509 510CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() 511{ 512 CleanupEntry &CE = CleanupEntries.back(); 513 514 llvm::BasicBlock *CleanupBlock = CE.CleanupBlock; 515 516 std::vector<llvm::BasicBlock *> Blocks; 517 std::swap(Blocks, CE.Blocks); 518 519 std::vector<llvm::BranchInst *> BranchFixups; 520 std::swap(BranchFixups, CE.BranchFixups); 521 522 CleanupEntries.pop_back(); 523 524 // Check if any branch fixups pointed to the scope we just popped. If so, 525 // we can remove them. 526 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 527 llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0); 528 BlockScopeMap::iterator I = BlockScopes.find(Dest); 529 530 if (I == BlockScopes.end()) 531 continue; 532 533 assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!"); 534 535 if (I->second == CleanupEntries.size()) { 536 // We don't need to do this branch fixup. 537 BranchFixups[i] = BranchFixups.back(); 538 BranchFixups.pop_back(); 539 i--; 540 e--; 541 continue; 542 } 543 } 544 545 llvm::BasicBlock *SwitchBlock = 0; 546 llvm::BasicBlock *EndBlock = 0; 547 if (!BranchFixups.empty()) { 548 SwitchBlock = createBasicBlock("cleanup.switch"); 549 EndBlock = createBasicBlock("cleanup.end"); 550 551 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 552 553 Builder.SetInsertPoint(SwitchBlock); 554 555 llvm::Value *DestCodePtr = CreateTempAlloca(llvm::Type::Int32Ty, 556 "cleanup.dst"); 557 llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp"); 558 559 // Create a switch instruction to determine where to jump next. 560 llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock, 561 BranchFixups.size()); 562 563 // Restore the current basic block (if any) 564 if (CurBB) 565 Builder.SetInsertPoint(CurBB); 566 else 567 Builder.ClearInsertionPoint(); 568 569 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 570 llvm::BranchInst *BI = BranchFixups[i]; 571 llvm::BasicBlock *Dest = BI->getSuccessor(0); 572 573 // Fixup the branch instruction to point to the cleanup block. 574 BI->setSuccessor(0, CleanupBlock); 575 576 if (CleanupEntries.empty()) { 577 llvm::ConstantInt *ID; 578 579 // Check if we already have a destination for this block. 580 if (Dest == SI->getDefaultDest()) 581 ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 582 else { 583 ID = SI->findCaseDest(Dest); 584 if (!ID) { 585 // No code found, get a new unique one by using the number of 586 // switch successors. 587 ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 588 SI->getNumSuccessors()); 589 SI->addCase(ID, Dest); 590 } 591 } 592 593 // Store the jump destination before the branch instruction. 594 new llvm::StoreInst(ID, DestCodePtr, BI); 595 } else { 596 // We need to jump through another cleanup block. Create a pad block 597 // with a branch instruction that jumps to the final destination and 598 // add it as a branch fixup to the current cleanup scope. 599 600 // Create the pad block. 601 llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn); 602 603 // Create a unique case ID. 604 llvm::ConstantInt *ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 605 SI->getNumSuccessors()); 606 607 // Store the jump destination before the branch instruction. 608 new llvm::StoreInst(ID, DestCodePtr, BI); 609 610 // Add it as the destination. 611 SI->addCase(ID, CleanupPad); 612 613 // Create the branch to the final destination. 614 llvm::BranchInst *BI = llvm::BranchInst::Create(Dest); 615 CleanupPad->getInstList().push_back(BI); 616 617 // And add it as a branch fixup. 618 CleanupEntries.back().BranchFixups.push_back(BI); 619 } 620 } 621 } 622 623 // Remove all blocks from the block scope map. 624 for (size_t i = 0, e = Blocks.size(); i != e; ++i) { 625 assert(BlockScopes.count(Blocks[i]) && 626 "Did not find block in scope map!"); 627 628 BlockScopes.erase(Blocks[i]); 629 } 630 631 return CleanupBlockInfo(CleanupBlock, SwitchBlock, EndBlock); 632} 633 634void CodeGenFunction::EmitCleanupBlock() 635{ 636 CleanupBlockInfo Info = PopCleanupBlock(); 637 638 EmitBlock(Info.CleanupBlock); 639 640 if (Info.SwitchBlock) 641 EmitBlock(Info.SwitchBlock); 642 if (Info.EndBlock) 643 EmitBlock(Info.EndBlock); 644} 645 646void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) 647{ 648 assert(!CleanupEntries.empty() && 649 "Trying to add branch fixup without cleanup block!"); 650 651 // FIXME: We could be more clever here and check if there's already a 652 // branch fixup for this destination and recycle it. 653 CleanupEntries.back().BranchFixups.push_back(BI); 654} 655 656void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) 657{ 658 if (!HaveInsertPoint()) 659 return; 660 661 llvm::BranchInst* BI = Builder.CreateBr(Dest); 662 663 Builder.ClearInsertionPoint(); 664 665 // The stack is empty, no need to do any cleanup. 666 if (CleanupEntries.empty()) 667 return; 668 669 if (!Dest->getParent()) { 670 // We are trying to branch to a block that hasn't been inserted yet. 671 AddBranchFixup(BI); 672 return; 673 } 674 675 BlockScopeMap::iterator I = BlockScopes.find(Dest); 676 if (I == BlockScopes.end()) { 677 // We are trying to jump to a block that is outside of any cleanup scope. 678 AddBranchFixup(BI); 679 return; 680 } 681 682 assert(I->second < CleanupEntries.size() && 683 "Trying to branch into cleanup region"); 684 685 if (I->second == CleanupEntries.size() - 1) { 686 // We have a branch to a block in the same scope. 687 return; 688 } 689 690 AddBranchFixup(BI); 691} 692