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