//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This coordinates the per-function state used while generating code. // //===----------------------------------------------------------------------===// #include "CodeGenFunction.h" #include "CodeGenModule.h" #include "CGCXXABI.h" #include "CGDebugInfo.h" #include "CGException.h" #include "clang/Basic/TargetInfo.h" #include "clang/AST/APValue.h" #include "clang/AST/ASTContext.h" #include "clang/AST/Decl.h" #include "clang/AST/DeclCXX.h" #include "clang/AST/StmtCXX.h" #include "clang/Frontend/CodeGenOptions.h" #include "llvm/Target/TargetData.h" #include "llvm/Intrinsics.h" using namespace clang; using namespace CodeGen; CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) : BlockFunction(cgm, *this, Builder), CGM(cgm), Target(CGM.getContext().Target), Builder(cgm.getModule().getContext()), NormalCleanupDest(0), EHCleanupDest(0), NextCleanupDestIndex(1), ExceptionSlot(0), DebugInfo(0), IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), DidCallStackSave(false), UnreachableBlock(0), CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0), ConditionalBranchLevel(0), TerminateLandingPad(0), TerminateHandler(0), TrapBB(0) { // Get some frequently used types. LLVMPointerWidth = Target.getPointerWidth(0); llvm::LLVMContext &LLVMContext = CGM.getLLVMContext(); IntPtrTy = llvm::IntegerType::get(LLVMContext, LLVMPointerWidth); Int32Ty = llvm::Type::getInt32Ty(LLVMContext); Int64Ty = llvm::Type::getInt64Ty(LLVMContext); Exceptions = getContext().getLangOptions().Exceptions; CatchUndefined = getContext().getLangOptions().CatchUndefined; CGM.getCXXABI().getMangleContext().startNewFunction(); } ASTContext &CodeGenFunction::getContext() const { return CGM.getContext(); } const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) { return CGM.getTypes().ConvertTypeForMem(T); } const llvm::Type *CodeGenFunction::ConvertType(QualType T) { return CGM.getTypes().ConvertType(T); } bool CodeGenFunction::hasAggregateLLVMType(QualType T) { return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() || T->isObjCObjectType(); } void CodeGenFunction::EmitReturnBlock() { // For cleanliness, we try to avoid emitting the return block for // simple cases. llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); if (CurBB) { assert(!CurBB->getTerminator() && "Unexpected terminated block."); // We have a valid insert point, reuse it if it is empty or there are no // explicit jumps to the return block. if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) { ReturnBlock.getBlock()->replaceAllUsesWith(CurBB); delete ReturnBlock.getBlock(); } else EmitBlock(ReturnBlock.getBlock()); return; } // Otherwise, if the return block is the target of a single direct // branch then we can just put the code in that block instead. This // cleans up functions which started with a unified return block. if (ReturnBlock.getBlock()->hasOneUse()) { llvm::BranchInst *BI = dyn_cast(*ReturnBlock.getBlock()->use_begin()); if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock.getBlock()) { // Reset insertion point and delete the branch. Builder.SetInsertPoint(BI->getParent()); BI->eraseFromParent(); delete ReturnBlock.getBlock(); return; } } // FIXME: We are at an unreachable point, there is no reason to emit the block // unless it has uses. However, we still need a place to put the debug // region.end for now. EmitBlock(ReturnBlock.getBlock()); } static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) { if (!BB) return; if (!BB->use_empty()) return CGF.CurFn->getBasicBlockList().push_back(BB); delete BB; } void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { assert(BreakContinueStack.empty() && "mismatched push/pop in break/continue stack!"); // Emit function epilog (to return). EmitReturnBlock(); EmitFunctionInstrumentation("__cyg_profile_func_exit"); // Emit debug descriptor for function end. if (CGDebugInfo *DI = getDebugInfo()) { DI->setLocation(EndLoc); DI->EmitFunctionEnd(Builder); } EmitFunctionEpilog(*CurFnInfo); EmitEndEHSpec(CurCodeDecl); assert(EHStack.empty() && "did not remove all scopes from cleanup stack!"); // If someone did an indirect goto, emit the indirect goto block at the end of // the function. if (IndirectBranch) { EmitBlock(IndirectBranch->getParent()); Builder.ClearInsertionPoint(); } // Remove the AllocaInsertPt instruction, which is just a convenience for us. llvm::Instruction *Ptr = AllocaInsertPt; AllocaInsertPt = 0; Ptr->eraseFromParent(); // If someone took the address of a label but never did an indirect goto, we // made a zero entry PHI node, which is illegal, zap it now. if (IndirectBranch) { llvm::PHINode *PN = cast(IndirectBranch->getAddress()); if (PN->getNumIncomingValues() == 0) { PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType())); PN->eraseFromParent(); } } EmitIfUsed(*this, RethrowBlock.getBlock()); EmitIfUsed(*this, TerminateLandingPad); EmitIfUsed(*this, TerminateHandler); EmitIfUsed(*this, UnreachableBlock); if (CGM.getCodeGenOpts().EmitDeclMetadata) EmitDeclMetadata(); } /// ShouldInstrumentFunction - Return true if the current function should be /// instrumented with __cyg_profile_func_* calls bool CodeGenFunction::ShouldInstrumentFunction() { if (!CGM.getCodeGenOpts().InstrumentFunctions) return false; if (CurFuncDecl->hasAttr()) return false; return true; } /// EmitFunctionInstrumentation - Emit LLVM code to call the specified /// instrumentation function with the current function and the call site, if /// function instrumentation is enabled. void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) { if (!ShouldInstrumentFunction()) return; const llvm::PointerType *PointerTy; const llvm::FunctionType *FunctionTy; std::vector ProfileFuncArgs; // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site); PointerTy = llvm::Type::getInt8PtrTy(VMContext); ProfileFuncArgs.push_back(PointerTy); ProfileFuncArgs.push_back(PointerTy); FunctionTy = llvm::FunctionType::get( llvm::Type::getVoidTy(VMContext), ProfileFuncArgs, false); llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn); llvm::CallInst *CallSite = Builder.CreateCall( CGM.getIntrinsic(llvm::Intrinsic::returnaddress, 0, 0), llvm::ConstantInt::get(Int32Ty, 0), "callsite"); Builder.CreateCall2(F, llvm::ConstantExpr::getBitCast(CurFn, PointerTy), CallSite); } void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy, llvm::Function *Fn, const FunctionArgList &Args, SourceLocation StartLoc) { const Decl *D = GD.getDecl(); DidCallStackSave = false; CurCodeDecl = CurFuncDecl = D; FnRetTy = RetTy; CurFn = Fn; assert(CurFn->isDeclaration() && "Function already has body?"); // Pass inline keyword to optimizer if it appears explicitly on any // declaration. if (const FunctionDecl *FD = dyn_cast_or_null(D)) for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(), RE = FD->redecls_end(); RI != RE; ++RI) if (RI->isInlineSpecified()) { Fn->addFnAttr(llvm::Attribute::InlineHint); break; } llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); // Create a marker to make it easy to insert allocas into the entryblock // later. Don't create this with the builder, because we don't want it // folded. llvm::Value *Undef = llvm::UndefValue::get(Int32Ty); AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB); if (Builder.isNamePreserving()) AllocaInsertPt->setName("allocapt"); ReturnBlock = getJumpDestInCurrentScope("return"); Builder.SetInsertPoint(EntryBB); QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0, false, false, 0, 0, /*FIXME?*/ FunctionType::ExtInfo()); // Emit subprogram debug descriptor. if (CGDebugInfo *DI = getDebugInfo()) { DI->setLocation(StartLoc); DI->EmitFunctionStart(GD, FnType, CurFn, Builder); } EmitFunctionInstrumentation("__cyg_profile_func_enter"); // FIXME: Leaked. // CC info is ignored, hopefully? CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args, FunctionType::ExtInfo()); if (RetTy->isVoidType()) { // Void type; nothing to return. ReturnValue = 0; } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect && hasAggregateLLVMType(CurFnInfo->getReturnType())) { // Indirect aggregate return; emit returned value directly into sret slot. // This reduces code size, and affects correctness in C++. ReturnValue = CurFn->arg_begin(); } else { ReturnValue = CreateIRTemp(RetTy, "retval"); } EmitStartEHSpec(CurCodeDecl); EmitFunctionProlog(*CurFnInfo, CurFn, Args); if (D && isa(D) && cast(D)->isInstance()) CGM.getCXXABI().EmitInstanceFunctionProlog(*this); // If any of the arguments have a variably modified type, make sure to // emit the type size. for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); i != e; ++i) { QualType Ty = i->second; if (Ty->isVariablyModifiedType()) EmitVLASize(Ty); } } void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { const FunctionDecl *FD = cast(CurGD.getDecl()); assert(FD->getBody()); EmitStmt(FD->getBody()); } /// Tries to mark the given function nounwind based on the /// non-existence of any throwing calls within it. We believe this is /// lightweight enough to do at -O0. static void TryMarkNoThrow(llvm::Function *F) { // LLVM treats 'nounwind' on a function as part of the type, so we // can't do this on functions that can be overwritten. if (F->mayBeOverridden()) return; for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) for (llvm::BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) if (llvm::CallInst *Call = dyn_cast(&*BI)) if (!Call->doesNotThrow()) return; F->setDoesNotThrow(true); } void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) { const FunctionDecl *FD = cast(GD.getDecl()); // Check if we should generate debug info for this function. if (CGM.getDebugInfo() && !FD->hasAttr()) DebugInfo = CGM.getDebugInfo(); FunctionArgList Args; QualType ResTy = FD->getResultType(); CurGD = GD; if (isa(FD) && cast(FD)->isInstance()) CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args); if (FD->getNumParams()) { const FunctionProtoType* FProto = FD->getType()->getAs(); assert(FProto && "Function def must have prototype!"); for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) Args.push_back(std::make_pair(FD->getParamDecl(i), FProto->getArgType(i))); } SourceRange BodyRange; if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange(); // Emit the standard function prologue. StartFunction(GD, ResTy, Fn, Args, BodyRange.getBegin()); // Generate the body of the function. if (isa(FD)) EmitDestructorBody(Args); else if (isa(FD)) EmitConstructorBody(Args); else EmitFunctionBody(Args); // Emit the standard function epilogue. FinishFunction(BodyRange.getEnd()); // If we haven't marked the function nothrow through other means, do // a quick pass now to see if we can. if (!CurFn->doesNotThrow()) TryMarkNoThrow(CurFn); } /// ContainsLabel - Return true if the statement contains a label in it. If /// this statement is not executed normally, it not containing a label means /// that we can just remove the code. bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) { // Null statement, not a label! if (S == 0) return false; // If this is a label, we have to emit the code, consider something like: // if (0) { ... foo: bar(); } goto foo; if (isa(S)) return true; // If this is a case/default statement, and we haven't seen a switch, we have // to emit the code. if (isa(S) && !IgnoreCaseStmts) return true; // If this is a switch statement, we want to ignore cases below it. if (isa(S)) IgnoreCaseStmts = true; // Scan subexpressions for verboten labels. for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); I != E; ++I) if (ContainsLabel(*I, IgnoreCaseStmts)) return true; return false; } /// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to /// a constant, or if it does but contains a label, return 0. If it constant /// folds to 'true' and does not contain a label, return 1, if it constant folds /// to 'false' and does not contain a label, return -1. int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) { // FIXME: Rename and handle conversion of other evaluatable things // to bool. Expr::EvalResult Result; if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() || Result.HasSideEffects) return 0; // Not foldable, not integer or not fully evaluatable. if (CodeGenFunction::ContainsLabel(Cond)) return 0; // Contains a label. return Result.Val.getInt().getBoolValue() ? 1 : -1; } /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if /// statement) to the specified blocks. Based on the condition, this might try /// to simplify the codegen of the conditional based on the branch. /// void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, llvm::BasicBlock *TrueBlock, llvm::BasicBlock *FalseBlock) { if (const ParenExpr *PE = dyn_cast(Cond)) return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); if (const BinaryOperator *CondBOp = dyn_cast(Cond)) { // Handle X && Y in a condition. if (CondBOp->getOpcode() == BO_LAnd) { // If we have "1 && X", simplify the code. "0 && X" would have constant // folded if the case was simple enough. if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) { // br(1 && X) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); } // If we have "X && 1", simplify the code to use an uncond branch. // "X && 0" would have been constant folded to 0. if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) { // br(X && 1) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); } // Emit the LHS as a conditional. If the LHS conditional is false, we // want to jump to the FalseBlock. llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true"); EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock); EmitBlock(LHSTrue); // Any temporaries created here are conditional. BeginConditionalBranch(); EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); EndConditionalBranch(); return; } else if (CondBOp->getOpcode() == BO_LOr) { // If we have "0 || X", simplify the code. "1 || X" would have constant // folded if the case was simple enough. if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) { // br(0 || X) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); } // If we have "X || 0", simplify the code to use an uncond branch. // "X || 1" would have been constant folded to 1. if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) { // br(X || 0) -> br(X). return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock); } // Emit the LHS as a conditional. If the LHS conditional is true, we // want to jump to the TrueBlock. llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false"); EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse); EmitBlock(LHSFalse); // Any temporaries created here are conditional. BeginConditionalBranch(); EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); EndConditionalBranch(); return; } } if (const UnaryOperator *CondUOp = dyn_cast(Cond)) { // br(!x, t, f) -> br(x, f, t) if (CondUOp->getOpcode() == UO_LNot) return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); } if (const ConditionalOperator *CondOp = dyn_cast(Cond)) { // Handle ?: operator. // Just ignore GNU ?: extension. if (CondOp->getLHS()) { // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f)) llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true"); llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false"); EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock); EmitBlock(LHSBlock); EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock); EmitBlock(RHSBlock); EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock); return; } } // Emit the code with the fully general case. llvm::Value *CondV = EvaluateExprAsBool(Cond); Builder.CreateCondBr(CondV, TrueBlock, FalseBlock); } /// ErrorUnsupported - Print out an error that codegen doesn't support the /// specified stmt yet. void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type, bool OmitOnError) { CGM.ErrorUnsupported(S, Type, OmitOnError); } void CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) { // Ignore empty classes in C++. if (getContext().getLangOptions().CPlusPlus) { if (const RecordType *RT = Ty->getAs()) { if (cast(RT->getDecl())->isEmpty()) return; } } // Cast the dest ptr to the appropriate i8 pointer type. unsigned DestAS = cast(DestPtr->getType())->getAddressSpace(); const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext, DestAS); if (DestPtr->getType() != BP) DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); // Get size and alignment info for this aggregate. std::pair TypeInfo = getContext().getTypeInfo(Ty); uint64_t Size = TypeInfo.first; unsigned Align = TypeInfo.second; // Don't bother emitting a zero-byte memset. if (Size == 0) return; llvm::ConstantInt *SizeVal = llvm::ConstantInt::get(IntPtrTy, Size / 8); llvm::ConstantInt *AlignVal = Builder.getInt32(Align / 8); // If the type contains a pointer to data member we can't memset it to zero. // Instead, create a null constant and copy it to the destination. if (!CGM.getTypes().isZeroInitializable(Ty)) { llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty); llvm::GlobalVariable *NullVariable = new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(), /*isConstant=*/true, llvm::GlobalVariable::PrivateLinkage, NullConstant, llvm::Twine()); llvm::Value *SrcPtr = Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy()); // FIXME: variable-size types? // Get and call the appropriate llvm.memcpy overload. llvm::Constant *Memcpy = CGM.getMemCpyFn(DestPtr->getType(), SrcPtr->getType(), IntPtrTy); Builder.CreateCall5(Memcpy, DestPtr, SrcPtr, SizeVal, AlignVal, /*volatile*/ Builder.getFalse()); return; } // Otherwise, just memset the whole thing to zero. This is legal // because in LLVM, all default initializers (other than the ones we just // handled above) are guaranteed to have a bit pattern of all zeros. // FIXME: Handle variable sized types. Builder.CreateCall5(CGM.getMemSetFn(BP, IntPtrTy), DestPtr, Builder.getInt8(0), SizeVal, AlignVal, /*volatile*/ Builder.getFalse()); } llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelStmt *L) { // Make sure that there is a block for the indirect goto. if (IndirectBranch == 0) GetIndirectGotoBlock(); llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock(); // Make sure the indirect branch includes all of the address-taken blocks. IndirectBranch->addDestination(BB); return llvm::BlockAddress::get(CurFn, BB); } llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() { // If we already made the indirect branch for indirect goto, return its block. if (IndirectBranch) return IndirectBranch->getParent(); CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto")); const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext); // Create the PHI node that indirect gotos will add entries to. llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest"); // Create the indirect branch instruction. IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal); return IndirectBranch->getParent(); } llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) { llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; assert(SizeEntry && "Did not emit size for type"); return SizeEntry; } llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) { assert(Ty->isVariablyModifiedType() && "Must pass variably modified type to EmitVLASizes!"); EnsureInsertPoint(); if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()]; if (!SizeEntry) { const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); // Get the element size; QualType ElemTy = VAT->getElementType(); llvm::Value *ElemSize; if (ElemTy->isVariableArrayType()) ElemSize = EmitVLASize(ElemTy); else ElemSize = llvm::ConstantInt::get(SizeTy, getContext().getTypeSizeInChars(ElemTy).getQuantity()); llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp"); SizeEntry = Builder.CreateMul(ElemSize, NumElements); } return SizeEntry; } if (const ArrayType *AT = dyn_cast(Ty)) { EmitVLASize(AT->getElementType()); return 0; } const PointerType *PT = Ty->getAs(); assert(PT && "unknown VM type!"); EmitVLASize(PT->getPointeeType()); return 0; } llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { if (CGM.getContext().getBuiltinVaListType()->isArrayType()) return EmitScalarExpr(E); return EmitLValue(E).getAddress(); } /// Pops cleanup blocks until the given savepoint is reached. void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) { assert(Old.isValid()); while (EHStack.stable_begin() != Old) { EHCleanupScope &Scope = cast(*EHStack.begin()); // As long as Old strictly encloses the scope's enclosing normal // cleanup, we're going to emit another normal cleanup which // fallthrough can propagate through. bool FallThroughIsBranchThrough = Old.strictlyEncloses(Scope.getEnclosingNormalCleanup()); PopCleanupBlock(FallThroughIsBranchThrough); } } static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF, EHCleanupScope &Scope) { assert(Scope.isNormalCleanup()); llvm::BasicBlock *Entry = Scope.getNormalBlock(); if (!Entry) { Entry = CGF.createBasicBlock("cleanup"); Scope.setNormalBlock(Entry); } return Entry; } static llvm::BasicBlock *CreateEHEntry(CodeGenFunction &CGF, EHCleanupScope &Scope) { assert(Scope.isEHCleanup()); llvm::BasicBlock *Entry = Scope.getEHBlock(); if (!Entry) { Entry = CGF.createBasicBlock("eh.cleanup"); Scope.setEHBlock(Entry); } return Entry; } /// Transitions the terminator of the given exit-block of a cleanup to /// be a cleanup switch. static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF, llvm::BasicBlock *Block) { // If it's a branch, turn it into a switch whose default // destination is its original target. llvm::TerminatorInst *Term = Block->getTerminator(); assert(Term && "can't transition block without terminator"); if (llvm::BranchInst *Br = dyn_cast(Term)) { assert(Br->isUnconditional()); llvm::LoadInst *Load = new llvm::LoadInst(CGF.getNormalCleanupDestSlot(), "cleanup.dest", Term); llvm::SwitchInst *Switch = llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block); Br->eraseFromParent(); return Switch; } else { return cast(Term); } } /// Attempts to reduce a cleanup's entry block to a fallthrough. This /// is basically llvm::MergeBlockIntoPredecessor, except /// simplified/optimized for the tighter constraints on cleanup blocks. /// /// Returns the new block, whatever it is. static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF, llvm::BasicBlock *Entry) { llvm::BasicBlock *Pred = Entry->getSinglePredecessor(); if (!Pred) return Entry; llvm::BranchInst *Br = dyn_cast(Pred->getTerminator()); if (!Br || Br->isConditional()) return Entry; assert(Br->getSuccessor(0) == Entry); // If we were previously inserting at the end of the cleanup entry // block, we'll need to continue inserting at the end of the // predecessor. bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry; assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end()); // Kill the branch. Br->eraseFromParent(); // Merge the blocks. Pred->getInstList().splice(Pred->end(), Entry->getInstList()); // Kill the entry block. Entry->eraseFromParent(); if (WasInsertBlock) CGF.Builder.SetInsertPoint(Pred); return Pred; } static void EmitCleanup(CodeGenFunction &CGF, EHScopeStack::Cleanup *Fn, bool ForEH) { if (ForEH) CGF.EHStack.pushTerminate(); Fn->Emit(CGF, ForEH); if (ForEH) CGF.EHStack.popTerminate(); assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?"); } /// Pops a cleanup block. If the block includes a normal cleanup, the /// current insertion point is threaded through the cleanup, as are /// any branch fixups on the cleanup. void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) { assert(!EHStack.empty() && "cleanup stack is empty!"); assert(isa(*EHStack.begin()) && "top not a cleanup!"); EHCleanupScope &Scope = cast(*EHStack.begin()); assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups()); assert(Scope.isActive() && "cleanup was still inactive when popped!"); // Check whether we need an EH cleanup. This is only true if we've // generated a lazy EH cleanup block. bool RequiresEHCleanup = Scope.hasEHBranches(); // Check the three conditions which might require a normal cleanup: // - whether there are branch fix-ups through this cleanup unsigned FixupDepth = Scope.getFixupDepth(); bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth; // - whether there are branch-throughs or branch-afters bool HasExistingBranches = Scope.hasBranches(); // - whether there's a fallthrough llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock(); bool HasFallthrough = (FallthroughSource != 0); bool RequiresNormalCleanup = false; if (Scope.isNormalCleanup() && (HasFixups || HasExistingBranches || HasFallthrough)) { RequiresNormalCleanup = true; } // If we don't need the cleanup at all, we're done. if (!RequiresNormalCleanup && !RequiresEHCleanup) { EHStack.popCleanup(); // safe because there are no fixups assert(EHStack.getNumBranchFixups() == 0 || EHStack.hasNormalCleanups()); return; } // Copy the cleanup emission data out. Note that SmallVector // guarantees maximal alignment for its buffer regardless of its // type parameter. llvm::SmallVector CleanupBuffer; CleanupBuffer.reserve(Scope.getCleanupSize()); memcpy(CleanupBuffer.data(), Scope.getCleanupBuffer(), Scope.getCleanupSize()); CleanupBuffer.set_size(Scope.getCleanupSize()); EHScopeStack::Cleanup *Fn = reinterpret_cast(CleanupBuffer.data()); // We want to emit the EH cleanup after the normal cleanup, but go // ahead and do the setup for the EH cleanup while the scope is still // alive. llvm::BasicBlock *EHEntry = 0; llvm::SmallVector EHInstsToAppend; if (RequiresEHCleanup) { EHEntry = CreateEHEntry(*this, Scope); // Figure out the branch-through dest if necessary. llvm::BasicBlock *EHBranchThroughDest = 0; if (Scope.hasEHBranchThroughs()) { assert(Scope.getEnclosingEHCleanup() != EHStack.stable_end()); EHScope &S = *EHStack.find(Scope.getEnclosingEHCleanup()); EHBranchThroughDest = CreateEHEntry(*this, cast(S)); } // If we have exactly one branch-after and no branch-throughs, we // can dispatch it without a switch. if (!Scope.hasEHBranchThroughs() && Scope.getNumEHBranchAfters() == 1) { assert(!EHBranchThroughDest); // TODO: remove the spurious eh.cleanup.dest stores if this edge // never went through any switches. llvm::BasicBlock *BranchAfterDest = Scope.getEHBranchAfterBlock(0); EHInstsToAppend.push_back(llvm::BranchInst::Create(BranchAfterDest)); // Otherwise, if we have any branch-afters, we need a switch. } else if (Scope.getNumEHBranchAfters()) { // The default of the switch belongs to the branch-throughs if // they exist. llvm::BasicBlock *Default = (EHBranchThroughDest ? EHBranchThroughDest : getUnreachableBlock()); const unsigned SwitchCapacity = Scope.getNumEHBranchAfters(); llvm::LoadInst *Load = new llvm::LoadInst(getEHCleanupDestSlot(), "cleanup.dest"); llvm::SwitchInst *Switch = llvm::SwitchInst::Create(Load, Default, SwitchCapacity); EHInstsToAppend.push_back(Load); EHInstsToAppend.push_back(Switch); for (unsigned I = 0, E = Scope.getNumEHBranchAfters(); I != E; ++I) Switch->addCase(Scope.getEHBranchAfterIndex(I), Scope.getEHBranchAfterBlock(I)); // Otherwise, we have only branch-throughs; jump to the next EH // cleanup. } else { assert(EHBranchThroughDest); EHInstsToAppend.push_back(llvm::BranchInst::Create(EHBranchThroughDest)); } } if (!RequiresNormalCleanup) { EHStack.popCleanup(); } else { // As a kindof crazy internal case, branch-through fall-throughs // leave the insertion point set to the end of the last cleanup. bool HasPrebranchedFallthrough = (HasFallthrough && FallthroughSource->getTerminator()); assert(!HasPrebranchedFallthrough || FallthroughSource->getTerminator()->getSuccessor(0) == Scope.getNormalBlock()); // If we have a fallthrough and no other need for the cleanup, // emit it directly. if (HasFallthrough && !HasPrebranchedFallthrough && !HasFixups && !HasExistingBranches) { // Fixups can cause us to optimistically create a normal block, // only to later have no real uses for it. Just delete it in // this case. // TODO: we can potentially simplify all the uses after this. if (Scope.getNormalBlock()) { Scope.getNormalBlock()->replaceAllUsesWith(getUnreachableBlock()); delete Scope.getNormalBlock(); } EHStack.popCleanup(); EmitCleanup(*this, Fn, /*ForEH*/ false); // Otherwise, the best approach is to thread everything through // the cleanup block and then try to clean up after ourselves. } else { // Force the entry block to exist. llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope); // If there's a fallthrough, we need to store the cleanup // destination index. For fall-throughs this is always zero. if (HasFallthrough && !HasPrebranchedFallthrough) Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot()); // Emit the entry block. This implicitly branches to it if we // have fallthrough. All the fixups and existing branches should // already be branched to it. EmitBlock(NormalEntry); bool HasEnclosingCleanups = (Scope.getEnclosingNormalCleanup() != EHStack.stable_end()); // Compute the branch-through dest if we need it: // - if there are branch-throughs threaded through the scope // - if fall-through is a branch-through // - if there are fixups that will be optimistically forwarded // to the enclosing cleanup llvm::BasicBlock *BranchThroughDest = 0; if (Scope.hasBranchThroughs() || (HasFallthrough && FallthroughIsBranchThrough) || (HasFixups && HasEnclosingCleanups)) { assert(HasEnclosingCleanups); EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup()); BranchThroughDest = CreateNormalEntry(*this, cast(S)); } llvm::BasicBlock *FallthroughDest = 0; llvm::SmallVector InstsToAppend; // If there's exactly one branch-after and no other threads, // we can route it without a switch. if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough && Scope.getNumBranchAfters() == 1) { assert(!BranchThroughDest); // TODO: clean up the possibly dead stores to the cleanup dest slot. llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0); InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter)); // Build a switch-out if we need it: // - if there are branch-afters threaded through the scope // - if fall-through is a branch-after // - if there are fixups that have nowhere left to go and // so must be immediately resolved } else if (Scope.getNumBranchAfters() || (HasFallthrough && !FallthroughIsBranchThrough) || (HasFixups && !HasEnclosingCleanups)) { llvm::BasicBlock *Default = (BranchThroughDest ? BranchThroughDest : getUnreachableBlock()); // TODO: base this on the number of branch-afters and fixups const unsigned SwitchCapacity = 10; llvm::LoadInst *Load = new llvm::LoadInst(getNormalCleanupDestSlot(), "cleanup.dest"); llvm::SwitchInst *Switch = llvm::SwitchInst::Create(Load, Default, SwitchCapacity); InstsToAppend.push_back(Load); InstsToAppend.push_back(Switch); // Branch-after fallthrough. if (HasFallthrough && !FallthroughIsBranchThrough) { FallthroughDest = createBasicBlock("cleanup.cont"); Switch->addCase(Builder.getInt32(0), FallthroughDest); } for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) { Switch->addCase(Scope.getBranchAfterIndex(I), Scope.getBranchAfterBlock(I)); } if (HasFixups && !HasEnclosingCleanups) ResolveAllBranchFixups(Switch); } else { // We should always have a branch-through destination in this case. assert(BranchThroughDest); InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest)); } // We're finally ready to pop the cleanup. EHStack.popCleanup(); assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups); EmitCleanup(*this, Fn, /*ForEH*/ false); // Append the prepared cleanup prologue from above. llvm::BasicBlock *NormalExit = Builder.GetInsertBlock(); for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I) NormalExit->getInstList().push_back(InstsToAppend[I]); // Optimistically hope that any fixups will continue falling through. for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups(); I < E; ++I) { BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I); if (!Fixup.Destination) continue; if (!Fixup.OptimisticBranchBlock) { new llvm::StoreInst(Builder.getInt32(Fixup.DestinationIndex), getNormalCleanupDestSlot(), Fixup.InitialBranch); Fixup.InitialBranch->setSuccessor(0, NormalEntry); } Fixup.OptimisticBranchBlock = NormalExit; } if (FallthroughDest) EmitBlock(FallthroughDest); else if (!HasFallthrough) Builder.ClearInsertionPoint(); // Check whether we can merge NormalEntry into a single predecessor. // This might invalidate (non-IR) pointers to NormalEntry. llvm::BasicBlock *NewNormalEntry = SimplifyCleanupEntry(*this, NormalEntry); // If it did invalidate those pointers, and NormalEntry was the same // as NormalExit, go back and patch up the fixups. if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit) for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups(); I < E; ++I) CGF.EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry; } } assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0); // Emit the EH cleanup if required. if (RequiresEHCleanup) { CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP(); EmitBlock(EHEntry); EmitCleanup(*this, Fn, /*ForEH*/ true); // Append the prepared cleanup prologue from above. llvm::BasicBlock *EHExit = Builder.GetInsertBlock(); for (unsigned I = 0, E = EHInstsToAppend.size(); I != E; ++I) EHExit->getInstList().push_back(EHInstsToAppend[I]); Builder.restoreIP(SavedIP); SimplifyCleanupEntry(*this, EHEntry); } } /// Terminate the current block by emitting a branch which might leave /// the current cleanup-protected scope. The target scope may not yet /// be known, in which case this will require a fixup. /// /// As a side-effect, this method clears the insertion point. void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) { assert(Dest.getScopeDepth().encloses(EHStack.getInnermostNormalCleanup()) && "stale jump destination"); if (!HaveInsertPoint()) return; // Create the branch. llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock()); // Calculate the innermost active normal cleanup. EHScopeStack::stable_iterator TopCleanup = EHStack.getInnermostActiveNormalCleanup(); // If we're not in an active normal cleanup scope, or if the // destination scope is within the innermost active normal cleanup // scope, we don't need to worry about fixups. if (TopCleanup == EHStack.stable_end() || TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid Builder.ClearInsertionPoint(); return; } // If we can't resolve the destination cleanup scope, just add this // to the current cleanup scope as a branch fixup. if (!Dest.getScopeDepth().isValid()) { BranchFixup &Fixup = EHStack.addBranchFixup(); Fixup.Destination = Dest.getBlock(); Fixup.DestinationIndex = Dest.getDestIndex(); Fixup.InitialBranch = BI; Fixup.OptimisticBranchBlock = 0; Builder.ClearInsertionPoint(); return; } // Otherwise, thread through all the normal cleanups in scope. // Store the index at the start. llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex()); new llvm::StoreInst(Index, getNormalCleanupDestSlot(), BI); // Adjust BI to point to the first cleanup block. { EHCleanupScope &Scope = cast(*EHStack.find(TopCleanup)); BI->setSuccessor(0, CreateNormalEntry(*this, Scope)); } // Add this destination to all the scopes involved. EHScopeStack::stable_iterator I = TopCleanup; EHScopeStack::stable_iterator E = Dest.getScopeDepth(); if (E.strictlyEncloses(I)) { while (true) { EHCleanupScope &Scope = cast(*EHStack.find(I)); assert(Scope.isNormalCleanup()); I = Scope.getEnclosingNormalCleanup(); // If this is the last cleanup we're propagating through, tell it // that there's a resolved jump moving through it. if (!E.strictlyEncloses(I)) { Scope.addBranchAfter(Index, Dest.getBlock()); break; } // Otherwise, tell the scope that there's a jump propoagating // through it. If this isn't new information, all the rest of // the work has been done before. if (!Scope.addBranchThrough(Dest.getBlock())) break; } } Builder.ClearInsertionPoint(); } void CodeGenFunction::EmitBranchThroughEHCleanup(UnwindDest Dest) { // We should never get invalid scope depths for an UnwindDest; that // implies that the destination wasn't set up correctly. assert(Dest.getScopeDepth().isValid() && "invalid scope depth on EH dest?"); if (!HaveInsertPoint()) return; // Create the branch. llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock()); // Calculate the innermost active cleanup. EHScopeStack::stable_iterator InnermostCleanup = EHStack.getInnermostActiveEHCleanup(); // If the destination is in the same EH cleanup scope as us, we // don't need to thread through anything. if (InnermostCleanup.encloses(Dest.getScopeDepth())) { Builder.ClearInsertionPoint(); return; } assert(InnermostCleanup != EHStack.stable_end()); // Store the index at the start. llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex()); new llvm::StoreInst(Index, getEHCleanupDestSlot(), BI); // Adjust BI to point to the first cleanup block. { EHCleanupScope &Scope = cast(*EHStack.find(InnermostCleanup)); BI->setSuccessor(0, CreateEHEntry(*this, Scope)); } // Add this destination to all the scopes involved. for (EHScopeStack::stable_iterator I = InnermostCleanup, E = Dest.getScopeDepth(); ; ) { assert(E.strictlyEncloses(I)); EHCleanupScope &Scope = cast(*EHStack.find(I)); assert(Scope.isEHCleanup()); I = Scope.getEnclosingEHCleanup(); // If this is the last cleanup we're propagating through, add this // as a branch-after. if (I == E) { Scope.addEHBranchAfter(Index, Dest.getBlock()); break; } // Otherwise, add it as a branch-through. If this isn't new // information, all the rest of the work has been done before. if (!Scope.addEHBranchThrough(Dest.getBlock())) break; } Builder.ClearInsertionPoint(); } /// All the branch fixups on the EH stack have propagated out past the /// outermost normal cleanup; resolve them all by adding cases to the /// given switch instruction. void CodeGenFunction::ResolveAllBranchFixups(llvm::SwitchInst *Switch) { llvm::SmallPtrSet CasesAdded; for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) { // Skip this fixup if its destination isn't set or if we've // already treated it. BranchFixup &Fixup = EHStack.getBranchFixup(I); if (Fixup.Destination == 0) continue; if (!CasesAdded.insert(Fixup.Destination)) continue; Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Fixup.Destination); } EHStack.clearFixups(); } void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) { assert(Block && "resolving a null target block"); if (!EHStack.getNumBranchFixups()) return; assert(EHStack.hasNormalCleanups() && "branch fixups exist with no normal cleanups on stack"); llvm::SmallPtrSet ModifiedOptimisticBlocks; bool ResolvedAny = false; for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) { // Skip this fixup if its destination doesn't match. BranchFixup &Fixup = EHStack.getBranchFixup(I); if (Fixup.Destination != Block) continue; Fixup.Destination = 0; ResolvedAny = true; // If it doesn't have an optimistic branch block, LatestBranch is // already pointing to the right place. llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock; if (!BranchBB) continue; // Don't process the same optimistic branch block twice. if (!ModifiedOptimisticBlocks.insert(BranchBB)) continue; llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB); // Add a case to the switch. Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block); } if (ResolvedAny) EHStack.popNullFixups(); } /// Activate a cleanup that was created in an inactivated state. void CodeGenFunction::ActivateCleanup(EHScopeStack::stable_iterator C) { assert(C != EHStack.stable_end() && "activating bottom of stack?"); EHCleanupScope &Scope = cast(*EHStack.find(C)); assert(!Scope.isActive() && "double activation"); // Calculate whether the cleanup was used: bool Used = false; // - as a normal cleanup if (Scope.isNormalCleanup()) { bool NormalUsed = false; if (Scope.getNormalBlock()) { NormalUsed = true; } else { // Check whether any enclosed cleanups were needed. for (EHScopeStack::stable_iterator I = EHStack.getInnermostNormalCleanup(); I != C; ) { assert(C.strictlyEncloses(I)); EHCleanupScope &S = cast(*EHStack.find(I)); if (S.getNormalBlock()) { NormalUsed = true; break; } I = S.getEnclosingNormalCleanup(); } } if (NormalUsed) Used = true; else Scope.setActivatedBeforeNormalUse(true); } // - as an EH cleanup if (Scope.isEHCleanup()) { bool EHUsed = false; if (Scope.getEHBlock()) { EHUsed = true; } else { // Check whether any enclosed cleanups were needed. for (EHScopeStack::stable_iterator I = EHStack.getInnermostEHCleanup(); I != C; ) { assert(C.strictlyEncloses(I)); EHCleanupScope &S = cast(*EHStack.find(I)); if (S.getEHBlock()) { EHUsed = true; break; } I = S.getEnclosingEHCleanup(); } } if (EHUsed) Used = true; else Scope.setActivatedBeforeEHUse(true); } llvm::AllocaInst *Var = EHCleanupScope::activeSentinel(); if (Used) { Var = CreateTempAlloca(Builder.getInt1Ty()); InitTempAlloca(Var, Builder.getFalse()); } Scope.setActiveVar(Var); } llvm::Value *CodeGenFunction::getNormalCleanupDestSlot() { if (!NormalCleanupDest) NormalCleanupDest = CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot"); return NormalCleanupDest; } llvm::Value *CodeGenFunction::getEHCleanupDestSlot() { if (!EHCleanupDest) EHCleanupDest = CreateTempAlloca(Builder.getInt32Ty(), "eh.cleanup.dest.slot"); return EHCleanupDest; } void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E, llvm::ConstantInt *Init) { assert (Init && "Invalid DeclRefExpr initializer!"); if (CGDebugInfo *Dbg = getDebugInfo()) Dbg->EmitGlobalVariable(E->getDecl(), Init, Builder); }