CodeGenFunction.cpp revision 0032b2781b4deb131f8c9b7968f2030bf2489cdd
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::getInt32Ty(VMContext)); 160 AllocaInsertPt = new llvm::BitCastInst(Undef, llvm::Type::getInt32Ty(VMContext), "", 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 SynthesizeDefaultConstructor(CD, FD, Fn, Args); 255 } 256 } 257 else if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) 258 if (MD->isCopyAssignment()) 259 SynthesizeCXXCopyAssignment(MD, FD, Fn, Args); 260 261 // Destroy the 'this' declaration. 262 if (CXXThisDecl) 263 CXXThisDecl->Destroy(getContext()); 264} 265 266/// ContainsLabel - Return true if the statement contains a label in it. If 267/// this statement is not executed normally, it not containing a label means 268/// that we can just remove the code. 269bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { 270 // Null statement, not a label! 271 if (S == 0) return false; 272 273 // If this is a label, we have to emit the code, consider something like: 274 // if (0) { ... foo: bar(); } goto foo; 275 if (isa<LabelStmt>(S)) 276 return true; 277 278 // If this is a case/default statement, and we haven't seen a switch, we have 279 // to emit the code. 280 if (isa<SwitchCase>(S) && !IgnoreCaseStmts) 281 return true; 282 283 // If this is a switch statement, we want to ignore cases below it. 284 if (isa<SwitchStmt>(S)) 285 IgnoreCaseStmts = true; 286 287 // Scan subexpressions for verboten labels. 288 for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 289 I != E; ++I) 290 if (ContainsLabel(*I, IgnoreCaseStmts)) 291 return true; 292 293 return false; 294} 295 296 297/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to 298/// a constant, or if it does but contains a label, return 0. If it constant 299/// folds to 'true' and does not contain a label, return 1, if it constant folds 300/// to 'false' and does not contain a label, return -1. 301int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { 302 // FIXME: Rename and handle conversion of other evaluatable things 303 // to bool. 304 Expr::EvalResult Result; 305 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || 306 Result.HasSideEffects) 307 return 0; // Not foldable, not integer or not fully evaluatable. 308 309 if (CodeGenFunction::ContainsLabel(Cond)) 310 return 0; // Contains a label. 311 312 return Result.Val.getInt().getBoolValue() ? 1 : -1; 313} 314 315 316/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if 317/// statement) to the specified blocks. Based on the condition, this might try 318/// to simplify the codegen of the conditional based on the branch. 319/// 320void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 321 llvm::BasicBlock *TrueBlock, 322 llvm::BasicBlock *FalseBlock) { 323 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) 324 return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); 325 326 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { 327 // Handle X && Y in a condition. 328 if (CondBOp->getOpcode() == BinaryOperator::LAnd) { 329 // If we have "1 && X", simplify the code. "0 && X" would have constant 330 // folded if the case was simple enough. 331 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { 332 // br(1 && X) -> br(X). 333 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 334 } 335 336 // If we have "X && 1", simplify the code to use an uncond branch. 337 // "X && 0" would have been constant folded to 0. 338 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) { 339 // br(X && 1) -> br(X). 340 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 341 } 342 343 // Emit the LHS as a conditional. If the LHS conditional is false, we 344 // want to jump to the FalseBlock. 345 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); 346 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); 347 EmitBlock(LHSTrue); 348 349 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 350 return; 351 } else if (CondBOp->getOpcode() == BinaryOperator::LOr) { 352 // If we have "0 || X", simplify the code. "1 || X" would have constant 353 // folded if the case was simple enough. 354 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { 355 // br(0 || X) -> br(X). 356 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 357 } 358 359 // If we have "X || 0", simplify the code to use an uncond branch. 360 // "X || 1" would have been constant folded to 1. 361 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) { 362 // br(X || 0) -> br(X). 363 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); 364 } 365 366 // Emit the LHS as a conditional. If the LHS conditional is true, we 367 // want to jump to the TrueBlock. 368 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); 369 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); 370 EmitBlock(LHSFalse); 371 372 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); 373 return; 374 } 375 } 376 377 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { 378 // br(!x, t, f) -> br(x, f, t) 379 if (CondUOp->getOpcode() == UnaryOperator::LNot) 380 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); 381 } 382 383 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) { 384 // Handle ?: operator. 385 386 // Just ignore GNU ?: extension. 387 if (CondOp->getLHS()) { 388 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) 389 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); 390 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); 391 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); 392 EmitBlock(LHSBlock); 393 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); 394 EmitBlock(RHSBlock); 395 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); 396 return; 397 } 398 } 399 400 // Emit the code with the fully general case. 401 llvm::Value *CondV = EvaluateExprAsBool(Cond); 402 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); 403} 404 405/// getCGRecordLayout - Return record layout info. 406const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT, 407 QualType Ty) { 408 const RecordType *RTy = Ty->getAs<RecordType>(); 409 assert (RTy && "Unexpected type. RecordType expected here."); 410 411 return CGT.getCGRecordLayout(RTy->getDecl()); 412} 413 414/// ErrorUnsupported - Print out an error that codegen doesn't support the 415/// specified stmt yet. 416void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, 417 bool OmitOnError) { 418 CGM.ErrorUnsupported(S, Type, OmitOnError); 419} 420 421unsigned CodeGenFunction::GetIDForAddrOfLabel(const LabelStmt *L) { 422 // Use LabelIDs.size() as the new ID if one hasn't been assigned. 423 return LabelIDs.insert(std::make_pair(L, LabelIDs.size())).first->second; 424} 425 426void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) { 427 const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext)); 428 if (DestPtr->getType() != BP) 429 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 430 431 // Get size and alignment info for this aggregate. 432 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 433 434 // Don't bother emitting a zero-byte memset. 435 if (TypeInfo.first == 0) 436 return; 437 438 // FIXME: Handle variable sized types. 439 const llvm::Type *IntPtr = llvm::IntegerType::get(VMContext, 440 LLVMPointerWidth); 441 442 Builder.CreateCall4(CGM.getMemSetFn(), DestPtr, 443 llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext)), 444 // TypeInfo.first describes size in bits. 445 llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), 446 llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 447 TypeInfo.second/8)); 448} 449 450void CodeGenFunction::EmitIndirectSwitches() { 451 llvm::BasicBlock *Default; 452 453 if (IndirectSwitches.empty()) 454 return; 455 456 if (!LabelIDs.empty()) { 457 Default = getBasicBlockForLabel(LabelIDs.begin()->first); 458 } else { 459 // No possible targets for indirect goto, just emit an infinite 460 // loop. 461 Default = createBasicBlock("indirectgoto.loop", CurFn); 462 llvm::BranchInst::Create(Default, Default); 463 } 464 465 for (std::vector<llvm::SwitchInst*>::iterator i = IndirectSwitches.begin(), 466 e = IndirectSwitches.end(); i != e; ++i) { 467 llvm::SwitchInst *I = *i; 468 469 I->setSuccessor(0, Default); 470 for (std::map<const LabelStmt*,unsigned>::iterator LI = LabelIDs.begin(), 471 LE = LabelIDs.end(); LI != LE; ++LI) { 472 I->addCase(llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 473 LI->second), 474 getBasicBlockForLabel(LI->first)); 475 } 476 } 477} 478 479llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { 480 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 481 482 assert(SizeEntry && "Did not emit size for type"); 483 return SizeEntry; 484} 485 486llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { 487 assert(Ty->isVariablyModifiedType() && 488 "Must pass variably modified type to EmitVLASizes!"); 489 490 EnsureInsertPoint(); 491 492 if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { 493 llvm::Value *&SizeEntry = VLASizeMap[VAT]; 494 495 if (!SizeEntry) { 496 // Get the element size; 497 llvm::Value *ElemSize; 498 499 QualType ElemTy = VAT->getElementType(); 500 501 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 502 503 if (ElemTy->isVariableArrayType()) 504 ElemSize = EmitVLASize(ElemTy); 505 else { 506 ElemSize = llvm::ConstantInt::get(SizeTy, 507 getContext().getTypeSize(ElemTy) / 8); 508 } 509 510 llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); 511 NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); 512 513 SizeEntry = Builder.CreateMul(ElemSize, NumElements); 514 } 515 516 return SizeEntry; 517 } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { 518 EmitVLASize(AT->getElementType()); 519 } else if (const PointerType *PT = Ty->getAs<PointerType>()) 520 EmitVLASize(PT->getPointeeType()); 521 else { 522 assert(0 && "unknown VM type!"); 523 } 524 525 return 0; 526} 527 528llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { 529 if (CGM.getContext().getBuiltinVaListType()->isArrayType()) { 530 return EmitScalarExpr(E); 531 } 532 return EmitLValue(E).getAddress(); 533} 534 535void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupBlock) 536{ 537 CleanupEntries.push_back(CleanupEntry(CleanupBlock)); 538} 539 540void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) 541{ 542 assert(CleanupEntries.size() >= OldCleanupStackSize && 543 "Cleanup stack mismatch!"); 544 545 while (CleanupEntries.size() > OldCleanupStackSize) 546 EmitCleanupBlock(); 547} 548 549CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() 550{ 551 CleanupEntry &CE = CleanupEntries.back(); 552 553 llvm::BasicBlock *CleanupBlock = CE.CleanupBlock; 554 555 std::vector<llvm::BasicBlock *> Blocks; 556 std::swap(Blocks, CE.Blocks); 557 558 std::vector<llvm::BranchInst *> BranchFixups; 559 std::swap(BranchFixups, CE.BranchFixups); 560 561 CleanupEntries.pop_back(); 562 563 // Check if any branch fixups pointed to the scope we just popped. If so, 564 // we can remove them. 565 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 566 llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0); 567 BlockScopeMap::iterator I = BlockScopes.find(Dest); 568 569 if (I == BlockScopes.end()) 570 continue; 571 572 assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!"); 573 574 if (I->second == CleanupEntries.size()) { 575 // We don't need to do this branch fixup. 576 BranchFixups[i] = BranchFixups.back(); 577 BranchFixups.pop_back(); 578 i--; 579 e--; 580 continue; 581 } 582 } 583 584 llvm::BasicBlock *SwitchBlock = 0; 585 llvm::BasicBlock *EndBlock = 0; 586 if (!BranchFixups.empty()) { 587 SwitchBlock = createBasicBlock("cleanup.switch"); 588 EndBlock = createBasicBlock("cleanup.end"); 589 590 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 591 592 Builder.SetInsertPoint(SwitchBlock); 593 594 llvm::Value *DestCodePtr = CreateTempAlloca(llvm::Type::getInt32Ty(VMContext), 595 "cleanup.dst"); 596 llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp"); 597 598 // Create a switch instruction to determine where to jump next. 599 llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock, 600 BranchFixups.size()); 601 602 // Restore the current basic block (if any) 603 if (CurBB) { 604 Builder.SetInsertPoint(CurBB); 605 606 // If we had a current basic block, we also need to emit an instruction 607 // to initialize the cleanup destination. 608 Builder.CreateStore(llvm::Constant::getNullValue(llvm::Type::getInt32Ty(VMContext)), 609 DestCodePtr); 610 } else 611 Builder.ClearInsertionPoint(); 612 613 for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) { 614 llvm::BranchInst *BI = BranchFixups[i]; 615 llvm::BasicBlock *Dest = BI->getSuccessor(0); 616 617 // Fixup the branch instruction to point to the cleanup block. 618 BI->setSuccessor(0, CleanupBlock); 619 620 if (CleanupEntries.empty()) { 621 llvm::ConstantInt *ID; 622 623 // Check if we already have a destination for this block. 624 if (Dest == SI->getDefaultDest()) 625 ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 0); 626 else { 627 ID = SI->findCaseDest(Dest); 628 if (!ID) { 629 // No code found, get a new unique one by using the number of 630 // switch successors. 631 ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 632 SI->getNumSuccessors()); 633 SI->addCase(ID, Dest); 634 } 635 } 636 637 // Store the jump destination before the branch instruction. 638 new llvm::StoreInst(ID, DestCodePtr, BI); 639 } else { 640 // We need to jump through another cleanup block. Create a pad block 641 // with a branch instruction that jumps to the final destination and 642 // add it as a branch fixup to the current cleanup scope. 643 644 // Create the pad block. 645 llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn); 646 647 // Create a unique case ID. 648 llvm::ConstantInt *ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 649 SI->getNumSuccessors()); 650 651 // Store the jump destination before the branch instruction. 652 new llvm::StoreInst(ID, DestCodePtr, BI); 653 654 // Add it as the destination. 655 SI->addCase(ID, CleanupPad); 656 657 // Create the branch to the final destination. 658 llvm::BranchInst *BI = llvm::BranchInst::Create(Dest); 659 CleanupPad->getInstList().push_back(BI); 660 661 // And add it as a branch fixup. 662 CleanupEntries.back().BranchFixups.push_back(BI); 663 } 664 } 665 } 666 667 // Remove all blocks from the block scope map. 668 for (size_t i = 0, e = Blocks.size(); i != e; ++i) { 669 assert(BlockScopes.count(Blocks[i]) && 670 "Did not find block in scope map!"); 671 672 BlockScopes.erase(Blocks[i]); 673 } 674 675 return CleanupBlockInfo(CleanupBlock, SwitchBlock, EndBlock); 676} 677 678void CodeGenFunction::EmitCleanupBlock() 679{ 680 CleanupBlockInfo Info = PopCleanupBlock(); 681 682 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 683 if (CurBB && !CurBB->getTerminator() && 684 Info.CleanupBlock->getNumUses() == 0) { 685 CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList()); 686 delete Info.CleanupBlock; 687 } else 688 EmitBlock(Info.CleanupBlock); 689 690 if (Info.SwitchBlock) 691 EmitBlock(Info.SwitchBlock); 692 if (Info.EndBlock) 693 EmitBlock(Info.EndBlock); 694} 695 696void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) 697{ 698 assert(!CleanupEntries.empty() && 699 "Trying to add branch fixup without cleanup block!"); 700 701 // FIXME: We could be more clever here and check if there's already a branch 702 // fixup for this destination and recycle it. 703 CleanupEntries.back().BranchFixups.push_back(BI); 704} 705 706void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) 707{ 708 if (!HaveInsertPoint()) 709 return; 710 711 llvm::BranchInst* BI = Builder.CreateBr(Dest); 712 713 Builder.ClearInsertionPoint(); 714 715 // The stack is empty, no need to do any cleanup. 716 if (CleanupEntries.empty()) 717 return; 718 719 if (!Dest->getParent()) { 720 // We are trying to branch to a block that hasn't been inserted yet. 721 AddBranchFixup(BI); 722 return; 723 } 724 725 BlockScopeMap::iterator I = BlockScopes.find(Dest); 726 if (I == BlockScopes.end()) { 727 // We are trying to jump to a block that is outside of any cleanup scope. 728 AddBranchFixup(BI); 729 return; 730 } 731 732 assert(I->second < CleanupEntries.size() && 733 "Trying to branch into cleanup region"); 734 735 if (I->second == CleanupEntries.size() - 1) { 736 // We have a branch to a block in the same scope. 737 return; 738 } 739 740 AddBranchFixup(BI); 741} 742