CodeGenFunction.cpp revision 237957c45774713f81fbd5394b3db4317fef0938
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 "clang/AST/DeclCXX.h" 22#include "llvm/Target/TargetData.h" 23using namespace clang; 24using namespace CodeGen; 25 26CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) 27 : BlockFunction(cgm, *this, Builder), CGM(cgm), 28 Target(CGM.getContext().Target), 29 Builder(cgm.getModule().getContext()), 30 DebugInfo(0), SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0), 31 CXXThisDecl(0) { 32 LLVMIntTy = ConvertType(getContext().IntTy); 33 LLVMPointerWidth = Target.getPointerWidth(0); 34} 35 36ASTContext &CodeGenFunction::getContext() const { 37 return CGM.getContext(); 38} 39 40 41llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) { 42 llvm::BasicBlock *&BB = LabelMap[S]; 43 if (BB) return BB; 44 45 // Create, but don't insert, the new block. 46 return BB = createBasicBlock(S->getName()); 47} 48 49llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) { 50 llvm::Value *Res = LocalDeclMap[VD]; 51 assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!"); 52 return Res; 53} 54 55llvm::Constant * 56CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) { 57 return cast<llvm::Constant>(GetAddrOfLocalVar(BVD)); 58} 59 60const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { 61 return CGM.getTypes().ConvertTypeForMem(T); 62} 63 64const llvm::Type *CodeGenFunction::ConvertType(QualType T) { 65 return CGM.getTypes().ConvertType(T); 66} 67 68bool CodeGenFunction::hasAggregateLLVMType(QualType T) { 69 // FIXME: Use positive checks instead of negative ones to be more robust in 70 // the face of extension. 71 return !T->hasPointerRepresentation() && !T->isRealType() && 72 !T->isVoidType() && !T->isVectorType() && !T->isFunctionType() && 73 !T->isBlockPointerType() && !T->isMemberPointerType(); 74} 75 76void CodeGenFunction::EmitReturnBlock() { 77 // For cleanliness, we try to avoid emitting the return block for 78 // simple cases. 79 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 80 81 if (CurBB) { 82 assert(!CurBB->getTerminator() && "Unexpected terminated block."); 83 84 // We have a valid insert point, reuse it if it is empty or there are no 85 // explicit jumps to the return block. 86 if (CurBB->empty() || ReturnBlock->use_empty()) { 87 ReturnBlock->replaceAllUsesWith(CurBB); 88 delete ReturnBlock; 89 } else 90 EmitBlock(ReturnBlock); 91 return; 92 } 93 94 // Otherwise, if the return block is the target of a single direct 95 // branch then we can just put the code in that block instead. This 96 // cleans up functions which started with a unified return block. 97 if (ReturnBlock->hasOneUse()) { 98 llvm::BranchInst *BI = 99 dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin()); 100 if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) { 101 // Reset insertion point and delete the branch. 102 Builder.SetInsertPoint(BI->getParent()); 103 BI->eraseFromParent(); 104 delete ReturnBlock; 105 return; 106 } 107 } 108 109 // FIXME: We are at an unreachable point, there is no reason to emit the block 110 // unless it has uses. However, we still need a place to put the debug 111 // region.end for now. 112 113 EmitBlock(ReturnBlock); 114} 115 116void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { 117 // Finish emission of indirect switches. 118 EmitIndirectSwitches(); 119 120 assert(BreakContinueStack.empty() && 121 "mismatched push/pop in break/continue stack!"); 122 assert(BlockScopes.empty() && 123 "did not remove all blocks from block scope map!"); 124 assert(CleanupEntries.empty() && 125 "mismatched push/pop in cleanup stack!"); 126 127 // Emit function epilog (to return). 128 EmitReturnBlock(); 129 130 // Emit debug descriptor for function end. 131 if (CGDebugInfo *DI = getDebugInfo()) { 132 DI->setLocation(EndLoc); 133 DI->EmitRegionEnd(CurFn, Builder); 134 } 135 136 EmitFunctionEpilog(*CurFnInfo, ReturnValue); 137 138 // Remove the AllocaInsertPt instruction, which is just a convenience for us. 139 llvm::Instruction *Ptr = AllocaInsertPt; 140 AllocaInsertPt = 0; 141 Ptr->eraseFromParent(); 142} 143 144void CodeGenFunction::StartFunction(const Decl *D, QualType RetTy, 145 llvm::Function *Fn, 146 const FunctionArgList &Args, 147 SourceLocation StartLoc) { 148 DidCallStackSave = false; 149 CurCodeDecl = CurFuncDecl = D; 150 FnRetTy = RetTy; 151 CurFn = Fn; 152 assert(CurFn->isDeclaration() && "Function already has body?"); 153 154 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); 155 156 // Create a marker to make it easy to insert allocas into the entryblock 157 // later. Don't create this with the builder, because we don't want it 158 // folded. 159 llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::Int32Ty); 160 AllocaInsertPt = new llvm::BitCastInst(Undef, llvm::Type::Int32Ty, "", 161 EntryBB); 162 if (Builder.isNamePreserving()) 163 AllocaInsertPt->setName("allocapt"); 164 165 ReturnBlock = createBasicBlock("return"); 166 ReturnValue = 0; 167 if (!RetTy->isVoidType()) 168 ReturnValue = CreateTempAlloca(ConvertType(RetTy), "retval"); 169 170 Builder.SetInsertPoint(EntryBB); 171 172 // Emit subprogram debug descriptor. 173 // FIXME: The cast here is a huge hack. 174 if (CGDebugInfo *DI = getDebugInfo()) { 175 DI->setLocation(StartLoc); 176 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) { 177 DI->EmitFunctionStart(CGM.getMangledName(FD), RetTy, CurFn, Builder); 178 } else { 179 // Just use LLVM function name. 180 181 // FIXME: Remove unnecessary conversion to std::string when API settles. 182 DI->EmitFunctionStart(std::string(Fn->getName()).c_str(), 183 RetTy, CurFn, Builder); 184 } 185 } 186 187 // FIXME: Leaked. 188 CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args); 189 EmitFunctionProlog(*CurFnInfo, CurFn, Args); 190 191 // If any of the arguments have a variably modified type, make sure to 192 // emit the type size. 193 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 194 i != e; ++i) { 195 QualType Ty = i->second; 196 197 if (Ty->isVariablyModifiedType()) 198 EmitVLASize(Ty); 199 } 200} 201 202void CodeGenFunction::GenerateCode(const FunctionDecl *FD, 203 llvm::Function *Fn) { 204 // Check if we should generate debug info for this function. 205 if (CGM.getDebugInfo() && !FD->hasAttr<NodebugAttr>()) 206 DebugInfo = CGM.getDebugInfo(); 207 208 FunctionArgList Args; 209 210 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) { 211 if (MD->isInstance()) { 212 // Create the implicit 'this' decl. 213 // FIXME: I'm not entirely sure I like using a fake decl just for code 214 // generation. Maybe we can come up with a better way? 215 CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0, SourceLocation(), 216 &getContext().Idents.get("this"), 217 MD->getThisType(getContext())); 218 Args.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType())); 219 } 220 } 221 222 if (FD->getNumParams()) { 223 const FunctionProtoType* FProto = FD->getType()->getAsFunctionProtoType(); 224 assert(FProto && "Function def must have prototype!"); 225 226 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) 227 Args.push_back(std::make_pair(FD->getParamDecl(i), 228 FProto->getArgType(i))); 229 } 230 231 // FIXME: Support CXXTryStmt here, too. 232 if (const CompoundStmt *S = FD->getCompoundBody()) { 233 StartFunction(FD, FD->getResultType(), Fn, Args, S->getLBracLoc()); 234 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) 235 EmitCtorPrologue(CD); 236 EmitStmt(S); 237 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD)) 238 EmitDtorEpilogue(DD); 239 FinishFunction(S->getRBracLoc()); 240 } 241 else 242 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 243 const CXXRecordDecl *ClassDecl = 244 cast<CXXRecordDecl>(CD->getDeclContext()); 245 (void) ClassDecl; 246 if (CD->isCopyConstructor(getContext())) { 247 assert(!ClassDecl->hasUserDeclaredCopyConstructor() && 248 "bogus constructor is being synthesize"); 249 SynthesizeCXXCopyConstructor(CD, FD, Fn, Args); 250 } 251 else { 252 assert(!ClassDecl->hasUserDeclaredConstructor() && 253 "bogus constructor is being synthesize"); 254 StartFunction(FD, FD->getResultType(), Fn, Args, SourceLocation()); 255 EmitCtorPrologue(CD); 256 FinishFunction(); 257 } 258 } 259 260 // Destroy the 'this' declaration. 261 if (CXXThisDecl) 262 CXXThisDecl->Destroy(getContext()); 263} 264 265/// ContainsLabel - Return true if the statement contains a label in it. If 266/// this statement is not executed normally, it not containing a label means 267/// that we can just remove the code. 268bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 269 // Null statement, not a label! 270 if (S == 0) return false; 271 272 // If this is a label, we have to emit the code, consider something like: 273 // if (0) { ... foo: bar(); } goto foo; 274 if (isa<LabelStmt>(S)) 275 return true; 276 277 // If this is a case/default statement, and we haven't seen a switch, we have 278 // to emit the code. 279 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 280 return true; 281 282 // If this is a switch statement, we want to ignore cases below it. 283 if (isa<SwitchStmt>(S)) 284 IgnoreCaseStmts = true; 285 286 // Scan subexpressions for verboten labels. 287 for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 288 I != E; ++I) 289 if (ContainsLabel(*I, IgnoreCaseStmts)) 290 return true; 291 292 return false; 293} 294 295 296/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to 297/// a constant, or if it does but contains a label, return 0. If it constant 298/// folds to 'true' and does not contain a label, return 1, if it constant folds 299/// to 'false' and does not contain a label, return -1. 300int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { 301 // FIXME: Rename and handle conversion of other evaluatable things 302 // to bool. 303 Expr::EvalResult Result; 304 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 305 Result.HasSideEffects) 306 return 0; // Not foldable, not integer or not fully evaluatable. 307 308 if (CodeGenFunction::ContainsLabel(Cond)) 309 return 0; // Contains a label. 310 311 return Result.Val.getInt().getBoolValue() ? 1 : -1; 312} 313 314 315/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 316/// statement) to the specified blocks. Based on the condition, this might try 317/// to simplify the codegen of the conditional based on the branch. 318/// 319void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 320 llvm::BasicBlock *TrueBlock, 321 llvm::BasicBlock *FalseBlock) { 322 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) 323 return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); 324 325 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 326 // Handle X && Y in a condition. 327 if (CondBOp->getOpcode() == BinaryOperator::LAnd) { 328 // If we have "1 && X", simplify the code. "0 && X" would have constant 329 // folded if the case was simple enough. 330 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { 331 // br(1 && X) -> br(X). 332 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 333 } 334 335 // If we have "X && 1", simplify the code to use an uncond branch. 336 // "X && 0" would have been constant folded to 0. 337 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) { 338 // br(X && 1) -> br(X). 339 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 340 } 341 342 // Emit the LHS as a conditional. If the LHS conditional is false, we 343 // want to jump to the FalseBlock. 344 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 345 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 346 EmitBlock(LHSTrue); 347 348 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 349 return; 350 } else if (CondBOp->getOpcode() == BinaryOperator::LOr) { 351 // If we have "0 || X", simplify the code. "1 || X" would have constant 352 // folded if the case was simple enough. 353 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { 354 // br(0 || X) -> br(X). 355 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 356 } 357 358 // If we have "X || 0", simplify the code to use an uncond branch. 359 // "X || 1" would have been constant folded to 1. 360 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) { 361 // br(X || 0) -> br(X). 362 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 363 } 364 365 // Emit the LHS as a conditional. If the LHS conditional is true, we 366 // want to jump to the TrueBlock. 367 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 368 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 369 EmitBlock(LHSFalse); 370 371 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 372 return; 373 } 374 } 375 376 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 377 // br(!x, t, f) -> br(x, f, t) 378 if (CondUOp->getOpcode() == UnaryOperator::LNot) 379 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 380 } 381 382 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 383 // Handle ?: operator. 384 385 // Just ignore GNU ?: extension. 386 if (CondOp->getLHS()) { 387 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 388 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 389 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 390 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 391 EmitBlock(LHSBlock); 392 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 393 EmitBlock(RHSBlock); 394 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 395 return; 396 } 397 } 398 399 // Emit the code with the fully general case. 400 llvm::Value *CondV = EvaluateExprAsBool(Cond); 401 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 402} 403 404/// getCGRecordLayout - Return record layout info. 405const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT, 406 QualType Ty) { 407 const RecordType *RTy = Ty->getAs<RecordType>(); 408 assert (RTy && "Unexpected type. RecordType expected here."); 409 410 return CGT.getCGRecordLayout(RTy->getDecl()); 411} 412 413/// ErrorUnsupported - Print out an error that codegen doesn't support the 414/// specified stmt yet. 415void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 416 bool OmitOnError) { 417 CGM.ErrorUnsupported(S, Type, OmitOnError); 418} 419 420unsigned CodeGenFunction::GetIDForAddrOfLabel(const LabelStmt *L) { 421 // Use LabelIDs.size() as the new ID if one hasn't been assigned. 422 return LabelIDs.insert(std::make_pair(L, LabelIDs.size())).first->second; 423} 424 425void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) { 426 const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 427 if (DestPtr->getType() != BP) 428 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 429 430 // Get size and alignment info for this aggregate. 431 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 432 433 // Don't bother emitting a zero-byte memset. 434 if (TypeInfo.first == 0) 435 return; 436 437 // FIXME: Handle variable sized types. 438 const llvm::Type *IntPtr = llvm::IntegerType::get(LLVMPointerWidth); 439 440 Builder.CreateCall4(CGM.getMemSetFn(), DestPtr, 441 llvm::Constant::getNullValue(llvm::Type::Int8Ty), 442 // TypeInfo.first describes size in bits. 443 llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), 444 llvm::ConstantInt::get(llvm::Type::Int32Ty, 445 TypeInfo.second/8)); 446} 447 448void CodeGenFunction::EmitIndirectSwitches() { 449 llvm::BasicBlock *Default; 450 451 if (IndirectSwitches.empty()) 452 return; 453 454 if (!LabelIDs.empty()) { 455 Default = getBasicBlockForLabel(LabelIDs.begin()->first); 456 } else { 457 // No possible targets for indirect goto, just emit an infinite 458 // loop. 459 Default = createBasicBlock("indirectgoto.loop", CurFn); 460 llvm::BranchInst::Create(Default, Default); 461 } 462 463 for (std::vector<llvm::SwitchInst*>::iterator i = IndirectSwitches.begin(), 464 e = IndirectSwitches.end(); i != e; ++i) { 465 llvm::SwitchInst *I = *i; 466 467 I->setSuccessor(0, Default); 468 for (std::map<const LabelStmt*,unsigned>::iterator LI = LabelIDs.begin(), 469 LE = LabelIDs.end(); LI != LE; ++LI) { 470 I->addCase(llvm::ConstantInt::get(llvm::Type::Int32Ty, 471 LI->second), 472 getBasicBlockForLabel(LI->first)); 473 } 474 } 475} 476 477llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 478 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 479 480 assert(SizeEntry && "Did not emit size for type"); 481 return SizeEntry; 482} 483 484llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 485 assert(Ty->isVariablyModifiedType() && 486 "Must pass variably modified type to EmitVLASizes!"); 487 488 EnsureInsertPoint(); 489 490 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 491 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 492 493 if (!SizeEntry) { 494 // Get the element size; 495 llvm::Value *ElemSize; 496 497 QualType ElemTy = VAT->getElementType(); 498 499 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 500 501 if (ElemTy->isVariableArrayType()) 502 ElemSize = EmitVLASize(ElemTy); 503 else { 504 ElemSize = llvm::ConstantInt::get(SizeTy, 505 getContext().getTypeSize(ElemTy) / 8); 506 } 507 508 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 509 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 510 511 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 512 } 513 514 return SizeEntry; 515 } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 516 EmitVLASize(AT->getElementType()); 517 } else if (const PointerType *PT = Ty->getAs<PointerType>()) 518 EmitVLASize(PT->getPointeeType()); 519 else { 520 assert(0 && "unknown VM type!"); 521 } 522 523 return 0; 524} 525 526llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 527 if (CGM.getContext().getBuiltinVaListType()->isArrayType()) { 528 return EmitScalarExpr(E); 529 } 530 return EmitLValue(E).getAddress(); 531} 532 533void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupBlock) 534{ 535 CleanupEntries.push_back(CleanupEntry(CleanupBlock)); 536} 537 538void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) 539{ 540 assert(CleanupEntries.size() >= OldCleanupStackSize && 541 "Cleanup stack mismatch!"); 542 543 while (CleanupEntries.size() > OldCleanupStackSize) 544 EmitCleanupBlock(); 545} 546 547CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() 548{ 549 CleanupEntry &CE = CleanupEntries.back(); 550 551 llvm::BasicBlock *CleanupBlock = CE.CleanupBlock; 552 553 std::vector<llvm::BasicBlock *> Blocks; 554 std::swap(Blocks, CE.Blocks); 555 556 std::vector<llvm::BranchInst *> BranchFixups; 557 std::swap(BranchFixups, CE.BranchFixups); 558 559 CleanupEntries.pop_back(); 560 561 // Check if any branch fixups pointed to the scope we just popped. If so, 562 // we can remove them. 563 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 564 llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0); 565 BlockScopeMap::iterator I = BlockScopes.find(Dest); 566 567 if (I == BlockScopes.end()) 568 continue; 569 570 assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!"); 571 572 if (I->second == CleanupEntries.size()) { 573 // We don't need to do this branch fixup. 574 BranchFixups[i] = BranchFixups.back(); 575 BranchFixups.pop_back(); 576 i--; 577 e--; 578 continue; 579 } 580 } 581 582 llvm::BasicBlock *SwitchBlock = 0; 583 llvm::BasicBlock *EndBlock = 0; 584 if (!BranchFixups.empty()) { 585 SwitchBlock = createBasicBlock("cleanup.switch"); 586 EndBlock = createBasicBlock("cleanup.end"); 587 588 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 589 590 Builder.SetInsertPoint(SwitchBlock); 591 592 llvm::Value *DestCodePtr = CreateTempAlloca(llvm::Type::Int32Ty, 593 "cleanup.dst"); 594 llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp"); 595 596 // Create a switch instruction to determine where to jump next. 597 llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock, 598 BranchFixups.size()); 599 600 // Restore the current basic block (if any) 601 if (CurBB) { 602 Builder.SetInsertPoint(CurBB); 603 604 // If we had a current basic block, we also need to emit an instruction 605 // to initialize the cleanup destination. 606 Builder.CreateStore(llvm::Constant::getNullValue(llvm::Type::Int32Ty), 607 DestCodePtr); 608 } else 609 Builder.ClearInsertionPoint(); 610 611 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 612 llvm::BranchInst *BI = BranchFixups[i]; 613 llvm::BasicBlock *Dest = BI->getSuccessor(0); 614 615 // Fixup the branch instruction to point to the cleanup block. 616 BI->setSuccessor(0, CleanupBlock); 617 618 if (CleanupEntries.empty()) { 619 llvm::ConstantInt *ID; 620 621 // Check if we already have a destination for this block. 622 if (Dest == SI->getDefaultDest()) 623 ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 624 else { 625 ID = SI->findCaseDest(Dest); 626 if (!ID) { 627 // No code found, get a new unique one by using the number of 628 // switch successors. 629 ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 630 SI->getNumSuccessors()); 631 SI->addCase(ID, Dest); 632 } 633 } 634 635 // Store the jump destination before the branch instruction. 636 new llvm::StoreInst(ID, DestCodePtr, BI); 637 } else { 638 // We need to jump through another cleanup block. Create a pad block 639 // with a branch instruction that jumps to the final destination and 640 // add it as a branch fixup to the current cleanup scope. 641 642 // Create the pad block. 643 llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn); 644 645 // Create a unique case ID. 646 llvm::ConstantInt *ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 647 SI->getNumSuccessors()); 648 649 // Store the jump destination before the branch instruction. 650 new llvm::StoreInst(ID, DestCodePtr, BI); 651 652 // Add it as the destination. 653 SI->addCase(ID, CleanupPad); 654 655 // Create the branch to the final destination. 656 llvm::BranchInst *BI = llvm::BranchInst::Create(Dest); 657 CleanupPad->getInstList().push_back(BI); 658 659 // And add it as a branch fixup. 660 CleanupEntries.back().BranchFixups.push_back(BI); 661 } 662 } 663 } 664 665 // Remove all blocks from the block scope map. 666 for (size_t i = 0, e = Blocks.size(); i != e; ++i) { 667 assert(BlockScopes.count(Blocks[i]) && 668 "Did not find block in scope map!"); 669 670 BlockScopes.erase(Blocks[i]); 671 } 672 673 return CleanupBlockInfo(CleanupBlock, SwitchBlock, EndBlock); 674} 675 676void CodeGenFunction::EmitCleanupBlock() 677{ 678 CleanupBlockInfo Info = PopCleanupBlock(); 679 680 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 681 if (CurBB && !CurBB->getTerminator() && 682 Info.CleanupBlock->getNumUses() == 0) { 683 CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList()); 684 delete Info.CleanupBlock; 685 } else 686 EmitBlock(Info.CleanupBlock); 687 688 if (Info.SwitchBlock) 689 EmitBlock(Info.SwitchBlock); 690 if (Info.EndBlock) 691 EmitBlock(Info.EndBlock); 692} 693 694void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) 695{ 696 assert(!CleanupEntries.empty() && 697 "Trying to add branch fixup without cleanup block!"); 698 699 // FIXME: We could be more clever here and check if there's already a branch 700 // fixup for this destination and recycle it. 701 CleanupEntries.back().BranchFixups.push_back(BI); 702} 703 704void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) 705{ 706 if (!HaveInsertPoint()) 707 return; 708 709 llvm::BranchInst* BI = Builder.CreateBr(Dest); 710 711 Builder.ClearInsertionPoint(); 712 713 // The stack is empty, no need to do any cleanup. 714 if (CleanupEntries.empty()) 715 return; 716 717 if (!Dest->getParent()) { 718 // We are trying to branch to a block that hasn't been inserted yet. 719 AddBranchFixup(BI); 720 return; 721 } 722 723 BlockScopeMap::iterator I = BlockScopes.find(Dest); 724 if (I == BlockScopes.end()) { 725 // We are trying to jump to a block that is outside of any cleanup scope. 726 AddBranchFixup(BI); 727 return; 728 } 729 730 assert(I->second < CleanupEntries.size() && 731 "Trying to branch into cleanup region"); 732 733 if (I->second == CleanupEntries.size() - 1) { 734 // We have a branch to a block in the same scope. 735 return; 736 } 737 738 AddBranchFixup(BI); 739} 740