CodeGenFunction.cpp revision 6217b80b7a1379b74cced1c076338262c3c980b3
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(); 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 = VMContext.getUndef(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<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 FinishFunction(S->getRBracLoc()); 238 } 239 240 // Destroy the 'this' declaration. 241 if (CXXThisDecl) 242 CXXThisDecl->Destroy(getContext()); 243} 244 245/// ContainsLabel - Return true if the statement contains a label in it. If 246/// this statement is not executed normally, it not containing a label means 247/// that we can just remove the code. 248bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 249 // Null statement, not a label! 250 if (S == 0) return false; 251 252 // If this is a label, we have to emit the code, consider something like: 253 // if (0) { ... foo: bar(); } goto foo; 254 if (isa<LabelStmt>(S)) 255 return true; 256 257 // If this is a case/default statement, and we haven't seen a switch, we have 258 // to emit the code. 259 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 260 return true; 261 262 // If this is a switch statement, we want to ignore cases below it. 263 if (isa<SwitchStmt>(S)) 264 IgnoreCaseStmts = true; 265 266 // Scan subexpressions for verboten labels. 267 for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 268 I != E; ++I) 269 if (ContainsLabel(*I, IgnoreCaseStmts)) 270 return true; 271 272 return false; 273} 274 275 276/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to 277/// a constant, or if it does but contains a label, return 0. If it constant 278/// folds to 'true' and does not contain a label, return 1, if it constant folds 279/// to 'false' and does not contain a label, return -1. 280int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { 281 // FIXME: Rename and handle conversion of other evaluatable things 282 // to bool. 283 Expr::EvalResult Result; 284 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 285 Result.HasSideEffects) 286 return 0; // Not foldable, not integer or not fully evaluatable. 287 288 if (CodeGenFunction::ContainsLabel(Cond)) 289 return 0; // Contains a label. 290 291 return Result.Val.getInt().getBoolValue() ? 1 : -1; 292} 293 294 295/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 296/// statement) to the specified blocks. Based on the condition, this might try 297/// to simplify the codegen of the conditional based on the branch. 298/// 299void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 300 llvm::BasicBlock *TrueBlock, 301 llvm::BasicBlock *FalseBlock) { 302 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) 303 return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); 304 305 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 306 // Handle X && Y in a condition. 307 if (CondBOp->getOpcode() == BinaryOperator::LAnd) { 308 // If we have "1 && X", simplify the code. "0 && X" would have constant 309 // folded if the case was simple enough. 310 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { 311 // br(1 && X) -> br(X). 312 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 313 } 314 315 // If we have "X && 1", simplify the code to use an uncond branch. 316 // "X && 0" would have been constant folded to 0. 317 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) { 318 // br(X && 1) -> br(X). 319 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 320 } 321 322 // Emit the LHS as a conditional. If the LHS conditional is false, we 323 // want to jump to the FalseBlock. 324 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 325 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 326 EmitBlock(LHSTrue); 327 328 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 329 return; 330 } else if (CondBOp->getOpcode() == BinaryOperator::LOr) { 331 // If we have "0 || X", simplify the code. "1 || X" would have constant 332 // folded if the case was simple enough. 333 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { 334 // br(0 || X) -> br(X). 335 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 336 } 337 338 // If we have "X || 0", simplify the code to use an uncond branch. 339 // "X || 1" would have been constant folded to 1. 340 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) { 341 // br(X || 0) -> br(X). 342 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 343 } 344 345 // Emit the LHS as a conditional. If the LHS conditional is true, we 346 // want to jump to the TrueBlock. 347 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 348 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 349 EmitBlock(LHSFalse); 350 351 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 352 return; 353 } 354 } 355 356 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 357 // br(!x, t, f) -> br(x, f, t) 358 if (CondUOp->getOpcode() == UnaryOperator::LNot) 359 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 360 } 361 362 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 363 // Handle ?: operator. 364 365 // Just ignore GNU ?: extension. 366 if (CondOp->getLHS()) { 367 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 368 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 369 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 370 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 371 EmitBlock(LHSBlock); 372 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 373 EmitBlock(RHSBlock); 374 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 375 return; 376 } 377 } 378 379 // Emit the code with the fully general case. 380 llvm::Value *CondV = EvaluateExprAsBool(Cond); 381 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 382} 383 384/// getCGRecordLayout - Return record layout info. 385const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT, 386 QualType Ty) { 387 const RecordType *RTy = Ty->getAs<RecordType>(); 388 assert (RTy && "Unexpected type. RecordType expected here."); 389 390 return CGT.getCGRecordLayout(RTy->getDecl()); 391} 392 393/// ErrorUnsupported - Print out an error that codegen doesn't support the 394/// specified stmt yet. 395void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 396 bool OmitOnError) { 397 CGM.ErrorUnsupported(S, Type, OmitOnError); 398} 399 400unsigned CodeGenFunction::GetIDForAddrOfLabel(const LabelStmt *L) { 401 // Use LabelIDs.size() as the new ID if one hasn't been assigned. 402 return LabelIDs.insert(std::make_pair(L, LabelIDs.size())).first->second; 403} 404 405void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) { 406 const llvm::Type *BP = VMContext.getPointerTypeUnqual(llvm::Type::Int8Ty); 407 if (DestPtr->getType() != BP) 408 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 409 410 // Get size and alignment info for this aggregate. 411 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 412 413 // Don't bother emitting a zero-byte memset. 414 if (TypeInfo.first == 0) 415 return; 416 417 // FIXME: Handle variable sized types. 418 const llvm::Type *IntPtr = VMContext.getIntegerType(LLVMPointerWidth); 419 420 Builder.CreateCall4(CGM.getMemSetFn(), DestPtr, 421 getLLVMContext().getNullValue(llvm::Type::Int8Ty), 422 // TypeInfo.first describes size in bits. 423 llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), 424 llvm::ConstantInt::get(llvm::Type::Int32Ty, 425 TypeInfo.second/8)); 426} 427 428void CodeGenFunction::EmitIndirectSwitches() { 429 llvm::BasicBlock *Default; 430 431 if (IndirectSwitches.empty()) 432 return; 433 434 if (!LabelIDs.empty()) { 435 Default = getBasicBlockForLabel(LabelIDs.begin()->first); 436 } else { 437 // No possible targets for indirect goto, just emit an infinite 438 // loop. 439 Default = createBasicBlock("indirectgoto.loop", CurFn); 440 llvm::BranchInst::Create(Default, Default); 441 } 442 443 for (std::vector<llvm::SwitchInst*>::iterator i = IndirectSwitches.begin(), 444 e = IndirectSwitches.end(); i != e; ++i) { 445 llvm::SwitchInst *I = *i; 446 447 I->setSuccessor(0, Default); 448 for (std::map<const LabelStmt*,unsigned>::iterator LI = LabelIDs.begin(), 449 LE = LabelIDs.end(); LI != LE; ++LI) { 450 I->addCase(llvm::ConstantInt::get(llvm::Type::Int32Ty, 451 LI->second), 452 getBasicBlockForLabel(LI->first)); 453 } 454 } 455} 456 457llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 458 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 459 460 assert(SizeEntry && "Did not emit size for type"); 461 return SizeEntry; 462} 463 464llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 465 assert(Ty->isVariablyModifiedType() && 466 "Must pass variably modified type to EmitVLASizes!"); 467 468 EnsureInsertPoint(); 469 470 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 471 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 472 473 if (!SizeEntry) { 474 // Get the element size; 475 llvm::Value *ElemSize; 476 477 QualType ElemTy = VAT->getElementType(); 478 479 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 480 481 if (ElemTy->isVariableArrayType()) 482 ElemSize = EmitVLASize(ElemTy); 483 else { 484 ElemSize = llvm::ConstantInt::get(SizeTy, 485 getContext().getTypeSize(ElemTy) / 8); 486 } 487 488 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 489 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 490 491 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 492 } 493 494 return SizeEntry; 495 } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 496 EmitVLASize(AT->getElementType()); 497 } else if (const PointerType *PT = Ty->getAs<PointerType>()) 498 EmitVLASize(PT->getPointeeType()); 499 else { 500 assert(0 && "unknown VM type!"); 501 } 502 503 return 0; 504} 505 506llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 507 if (CGM.getContext().getBuiltinVaListType()->isArrayType()) { 508 return EmitScalarExpr(E); 509 } 510 return EmitLValue(E).getAddress(); 511} 512 513void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupBlock) 514{ 515 CleanupEntries.push_back(CleanupEntry(CleanupBlock)); 516} 517 518void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) 519{ 520 assert(CleanupEntries.size() >= OldCleanupStackSize && 521 "Cleanup stack mismatch!"); 522 523 while (CleanupEntries.size() > OldCleanupStackSize) 524 EmitCleanupBlock(); 525} 526 527CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() 528{ 529 CleanupEntry &CE = CleanupEntries.back(); 530 531 llvm::BasicBlock *CleanupBlock = CE.CleanupBlock; 532 533 std::vector<llvm::BasicBlock *> Blocks; 534 std::swap(Blocks, CE.Blocks); 535 536 std::vector<llvm::BranchInst *> BranchFixups; 537 std::swap(BranchFixups, CE.BranchFixups); 538 539 CleanupEntries.pop_back(); 540 541 // Check if any branch fixups pointed to the scope we just popped. If so, 542 // we can remove them. 543 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 544 llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0); 545 BlockScopeMap::iterator I = BlockScopes.find(Dest); 546 547 if (I == BlockScopes.end()) 548 continue; 549 550 assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!"); 551 552 if (I->second == CleanupEntries.size()) { 553 // We don't need to do this branch fixup. 554 BranchFixups[i] = BranchFixups.back(); 555 BranchFixups.pop_back(); 556 i--; 557 e--; 558 continue; 559 } 560 } 561 562 llvm::BasicBlock *SwitchBlock = 0; 563 llvm::BasicBlock *EndBlock = 0; 564 if (!BranchFixups.empty()) { 565 SwitchBlock = createBasicBlock("cleanup.switch"); 566 EndBlock = createBasicBlock("cleanup.end"); 567 568 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 569 570 Builder.SetInsertPoint(SwitchBlock); 571 572 llvm::Value *DestCodePtr = CreateTempAlloca(llvm::Type::Int32Ty, 573 "cleanup.dst"); 574 llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp"); 575 576 // Create a switch instruction to determine where to jump next. 577 llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock, 578 BranchFixups.size()); 579 580 // Restore the current basic block (if any) 581 if (CurBB) { 582 Builder.SetInsertPoint(CurBB); 583 584 // If we had a current basic block, we also need to emit an instruction 585 // to initialize the cleanup destination. 586 Builder.CreateStore(getLLVMContext().getNullValue(llvm::Type::Int32Ty), 587 DestCodePtr); 588 } else 589 Builder.ClearInsertionPoint(); 590 591 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 592 llvm::BranchInst *BI = BranchFixups[i]; 593 llvm::BasicBlock *Dest = BI->getSuccessor(0); 594 595 // Fixup the branch instruction to point to the cleanup block. 596 BI->setSuccessor(0, CleanupBlock); 597 598 if (CleanupEntries.empty()) { 599 llvm::ConstantInt *ID; 600 601 // Check if we already have a destination for this block. 602 if (Dest == SI->getDefaultDest()) 603 ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 604 else { 605 ID = SI->findCaseDest(Dest); 606 if (!ID) { 607 // No code found, get a new unique one by using the number of 608 // switch successors. 609 ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 610 SI->getNumSuccessors()); 611 SI->addCase(ID, Dest); 612 } 613 } 614 615 // Store the jump destination before the branch instruction. 616 new llvm::StoreInst(ID, DestCodePtr, BI); 617 } else { 618 // We need to jump through another cleanup block. Create a pad block 619 // with a branch instruction that jumps to the final destination and 620 // add it as a branch fixup to the current cleanup scope. 621 622 // Create the pad block. 623 llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn); 624 625 // Create a unique case ID. 626 llvm::ConstantInt *ID = llvm::ConstantInt::get(llvm::Type::Int32Ty, 627 SI->getNumSuccessors()); 628 629 // Store the jump destination before the branch instruction. 630 new llvm::StoreInst(ID, DestCodePtr, BI); 631 632 // Add it as the destination. 633 SI->addCase(ID, CleanupPad); 634 635 // Create the branch to the final destination. 636 llvm::BranchInst *BI = llvm::BranchInst::Create(Dest); 637 CleanupPad->getInstList().push_back(BI); 638 639 // And add it as a branch fixup. 640 CleanupEntries.back().BranchFixups.push_back(BI); 641 } 642 } 643 } 644 645 // Remove all blocks from the block scope map. 646 for (size_t i = 0, e = Blocks.size(); i != e; ++i) { 647 assert(BlockScopes.count(Blocks[i]) && 648 "Did not find block in scope map!"); 649 650 BlockScopes.erase(Blocks[i]); 651 } 652 653 return CleanupBlockInfo(CleanupBlock, SwitchBlock, EndBlock); 654} 655 656void CodeGenFunction::EmitCleanupBlock() 657{ 658 CleanupBlockInfo Info = PopCleanupBlock(); 659 660 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 661 if (CurBB && !CurBB->getTerminator() && 662 Info.CleanupBlock->getNumUses() == 0) { 663 CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList()); 664 delete Info.CleanupBlock; 665 } else 666 EmitBlock(Info.CleanupBlock); 667 668 if (Info.SwitchBlock) 669 EmitBlock(Info.SwitchBlock); 670 if (Info.EndBlock) 671 EmitBlock(Info.EndBlock); 672} 673 674void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) 675{ 676 assert(!CleanupEntries.empty() && 677 "Trying to add branch fixup without cleanup block!"); 678 679 // FIXME: We could be more clever here and check if there's already a branch 680 // fixup for this destination and recycle it. 681 CleanupEntries.back().BranchFixups.push_back(BI); 682} 683 684void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) 685{ 686 if (!HaveInsertPoint()) 687 return; 688 689 llvm::BranchInst* BI = Builder.CreateBr(Dest); 690 691 Builder.ClearInsertionPoint(); 692 693 // The stack is empty, no need to do any cleanup. 694 if (CleanupEntries.empty()) 695 return; 696 697 if (!Dest->getParent()) { 698 // We are trying to branch to a block that hasn't been inserted yet. 699 AddBranchFixup(BI); 700 return; 701 } 702 703 BlockScopeMap::iterator I = BlockScopes.find(Dest); 704 if (I == BlockScopes.end()) { 705 // We are trying to jump to a block that is outside of any cleanup scope. 706 AddBranchFixup(BI); 707 return; 708 } 709 710 assert(I->second < CleanupEntries.size() && 711 "Trying to branch into cleanup region"); 712 713 if (I->second == CleanupEntries.size() - 1) { 714 // We have a branch to a block in the same scope. 715 return; 716 } 717 718 AddBranchFixup(BI); 719} 720