| //===--- 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 "CGDebugInfo.h" |
| #include "clang/Basic/TargetInfo.h" |
| #include "clang/AST/APValue.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/Decl.h" |
| #include "llvm/Support/CFG.h" |
| using namespace clang; |
| using namespace CodeGen; |
| |
| CodeGenFunction::CodeGenFunction(CodeGenModule &cgm) |
| : CGM(cgm), Target(CGM.getContext().Target), SwitchInsn(NULL), |
| CaseRangeBlock(NULL) { |
| LLVMIntTy = ConvertType(getContext().IntTy); |
| LLVMPointerWidth = Target.getPointerWidth(0); |
| } |
| |
| ASTContext &CodeGenFunction::getContext() const { |
| return CGM.getContext(); |
| } |
| |
| |
| llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) { |
| llvm::BasicBlock *&BB = LabelMap[S]; |
| if (BB) return BB; |
| |
| // Create, but don't insert, the new block. |
| return BB = createBasicBlock(S->getName()); |
| } |
| |
| llvm::Constant * |
| CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) { |
| return cast<llvm::Constant>(LocalDeclMap[BVD]); |
| } |
| |
| llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) |
| { |
| return LocalDeclMap[VD]; |
| } |
| |
| const llvm::Type *CodeGenFunction::ConvertType(QualType T) { |
| return CGM.getTypes().ConvertType(T); |
| } |
| |
| bool CodeGenFunction::isObjCPointerType(QualType T) { |
| // All Objective-C types are pointers. |
| return T->isObjCInterfaceType() || |
| T->isObjCQualifiedInterfaceType() || T->isObjCQualifiedIdType(); |
| } |
| |
| bool CodeGenFunction::hasAggregateLLVMType(QualType T) { |
| // FIXME: Use positive checks instead of negative ones to be more |
| // robust in the face of extension. |
| return !isObjCPointerType(T) &&!T->isRealType() && !T->isPointerLikeType() && |
| !T->isVoidType() && !T->isVectorType() && !T->isFunctionType() && |
| !T->isBlockPointerType(); |
| } |
| |
| 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 there are no explicit |
| // jumps to the return block. |
| if (ReturnBlock->use_empty()) |
| delete ReturnBlock; |
| else |
| EmitBlock(ReturnBlock); |
| 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->hasOneUse()) { |
| llvm::BranchInst *BI = |
| dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin()); |
| if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) { |
| // Reset insertion point and delete the branch. |
| Builder.SetInsertPoint(BI->getParent()); |
| BI->eraseFromParent(); |
| delete ReturnBlock; |
| 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); |
| } |
| |
| void CodeGenFunction::FinishFunction(SourceLocation EndLoc) { |
| // Finish emission of indirect switches. |
| EmitIndirectSwitches(); |
| |
| assert(BreakContinueStack.empty() && |
| "mismatched push/pop in break/continue stack!"); |
| |
| // Emit function epilog (to return). |
| EmitReturnBlock(); |
| |
| // Emit debug descriptor for function end. |
| if (CGDebugInfo *DI = CGM.getDebugInfo()) { |
| DI->setLocation(EndLoc); |
| DI->EmitRegionEnd(CurFn, Builder); |
| } |
| |
| EmitFunctionEpilog(*CurFnInfo, ReturnValue); |
| |
| // Remove the AllocaInsertPt instruction, which is just a convenience for us. |
| AllocaInsertPt->eraseFromParent(); |
| AllocaInsertPt = 0; |
| } |
| |
| void CodeGenFunction::StartFunction(const Decl *D, QualType RetTy, |
| llvm::Function *Fn, |
| const FunctionArgList &Args, |
| SourceLocation StartLoc) { |
| CurFuncDecl = D; |
| FnRetTy = RetTy; |
| CurFn = Fn; |
| assert(CurFn->isDeclaration() && "Function already has body?"); |
| |
| 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(llvm::Type::Int32Ty); |
| AllocaInsertPt = new llvm::BitCastInst(Undef, llvm::Type::Int32Ty, "allocapt", |
| EntryBB); |
| |
| ReturnBlock = createBasicBlock("return"); |
| ReturnValue = 0; |
| if (!RetTy->isVoidType()) |
| ReturnValue = CreateTempAlloca(ConvertType(RetTy), "retval"); |
| |
| Builder.SetInsertPoint(EntryBB); |
| |
| // Emit subprogram debug descriptor. |
| // FIXME: The cast here is a huge hack. |
| if (CGDebugInfo *DI = CGM.getDebugInfo()) { |
| DI->setLocation(StartLoc); |
| if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { |
| DI->EmitFunctionStart(FD->getIdentifier()->getName(), |
| RetTy, CurFn, Builder); |
| } else { |
| // Just use LLVM function name. |
| DI->EmitFunctionStart(Fn->getName().c_str(), |
| RetTy, CurFn, Builder); |
| } |
| } |
| |
| // FIXME: Leaked. |
| CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args); |
| EmitFunctionProlog(*CurFnInfo, CurFn, Args); |
| |
| // 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::GenerateCode(const FunctionDecl *FD, |
| llvm::Function *Fn) { |
| FunctionArgList Args; |
| if (FD->getNumParams()) { |
| const FunctionTypeProto* FProto = FD->getType()->getAsFunctionTypeProto(); |
| 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))); |
| } |
| |
| StartFunction(FD, FD->getResultType(), Fn, Args, |
| cast<CompoundStmt>(FD->getBody())->getLBracLoc()); |
| |
| EmitStmt(FD->getBody()); |
| |
| const CompoundStmt *S = dyn_cast<CompoundStmt>(FD->getBody()); |
| if (S) { |
| FinishFunction(S->getRBracLoc()); |
| } else { |
| FinishFunction(); |
| } |
| } |
| |
| /// 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<LabelStmt>(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<SwitchCase>(S) && !IgnoreCaseStmts) |
| return true; |
| |
| // If this is a switch statement, we want to ignore cases below it. |
| if (isa<SwitchStmt>(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<ParenExpr>(Cond)) |
| return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock); |
| |
| if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) { |
| // Handle X && Y in a condition. |
| if (CondBOp->getOpcode() == BinaryOperator::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); |
| |
| EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); |
| return; |
| } else if (CondBOp->getOpcode() == BinaryOperator::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); |
| |
| EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock); |
| return; |
| } |
| } |
| |
| if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) { |
| // br(!x, t, f) -> br(x, f, t) |
| if (CondUOp->getOpcode() == UnaryOperator::LNot) |
| return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock); |
| } |
| |
| if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(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); |
| } |
| |
| /// getCGRecordLayout - Return record layout info. |
| const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT, |
| QualType Ty) { |
| const RecordType *RTy = Ty->getAsRecordType(); |
| assert (RTy && "Unexpected type. RecordType expected here."); |
| |
| return CGT.getCGRecordLayout(RTy->getDecl()); |
| } |
| |
| /// 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); |
| } |
| |
| unsigned CodeGenFunction::GetIDForAddrOfLabel(const LabelStmt *L) { |
| // Use LabelIDs.size() as the new ID if one hasn't been assigned. |
| return LabelIDs.insert(std::make_pair(L, LabelIDs.size())).first->second; |
| } |
| |
| void CodeGenFunction::EmitMemSetToZero(llvm::Value *DestPtr, QualType Ty) |
| { |
| const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); |
| if (DestPtr->getType() != BP) |
| DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); |
| |
| // Get size and alignment info for this aggregate. |
| std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); |
| |
| // FIXME: Handle variable sized types. |
| const llvm::Type *IntPtr = llvm::IntegerType::get(LLVMPointerWidth); |
| |
| Builder.CreateCall4(CGM.getMemSetFn(), DestPtr, |
| llvm::ConstantInt::getNullValue(llvm::Type::Int8Ty), |
| // TypeInfo.first describes size in bits. |
| llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), |
| llvm::ConstantInt::get(llvm::Type::Int32Ty, |
| TypeInfo.second/8)); |
| } |
| |
| void CodeGenFunction::EmitIndirectSwitches() { |
| llvm::BasicBlock *Default; |
| |
| if (IndirectSwitches.empty()) |
| return; |
| |
| if (!LabelIDs.empty()) { |
| Default = getBasicBlockForLabel(LabelIDs.begin()->first); |
| } else { |
| // No possible targets for indirect goto, just emit an infinite |
| // loop. |
| Default = createBasicBlock("indirectgoto.loop", CurFn); |
| llvm::BranchInst::Create(Default, Default); |
| } |
| |
| for (std::vector<llvm::SwitchInst*>::iterator i = IndirectSwitches.begin(), |
| e = IndirectSwitches.end(); i != e; ++i) { |
| llvm::SwitchInst *I = *i; |
| |
| I->setSuccessor(0, Default); |
| for (std::map<const LabelStmt*,unsigned>::iterator LI = LabelIDs.begin(), |
| LE = LabelIDs.end(); LI != LE; ++LI) { |
| I->addCase(llvm::ConstantInt::get(llvm::Type::Int32Ty, |
| LI->second), |
| getBasicBlockForLabel(LI->first)); |
| } |
| } |
| } |
| |
| llvm::Value *CodeGenFunction::EmitVAArg(llvm::Value *VAListAddr, QualType Ty) |
| { |
| // FIXME: This entire method is hardcoded for 32-bit X86. |
| |
| const char *TargetPrefix = getContext().Target.getTargetPrefix(); |
| |
| if (strcmp(TargetPrefix, "x86") != 0 || |
| getContext().Target.getPointerWidth(0) != 32) |
| return 0; |
| |
| const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); |
| const llvm::Type *BPP = llvm::PointerType::getUnqual(BP); |
| |
| llvm::Value *VAListAddrAsBPP = Builder.CreateBitCast(VAListAddr, BPP, |
| "ap"); |
| llvm::Value *Addr = Builder.CreateLoad(VAListAddrAsBPP, "ap.cur"); |
| llvm::Value *AddrTyped = |
| Builder.CreateBitCast(Addr, |
| llvm::PointerType::getUnqual(ConvertType(Ty))); |
| |
| uint64_t SizeInBytes = getContext().getTypeSize(Ty) / 8; |
| const unsigned ArgumentSizeInBytes = 4; |
| if (SizeInBytes < ArgumentSizeInBytes) |
| SizeInBytes = ArgumentSizeInBytes; |
| |
| llvm::Value *NextAddr = |
| Builder.CreateGEP(Addr, |
| llvm::ConstantInt::get(llvm::Type::Int32Ty, SizeInBytes), |
| "ap.next"); |
| Builder.CreateStore(NextAddr, VAListAddrAsBPP); |
| |
| return AddrTyped; |
| } |
| |
| |
| llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) |
| { |
| llvm::Value *&SizeEntry = VLASizeMap[VAT]; |
| |
| 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!"); |
| |
| if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) { |
| llvm::Value *&SizeEntry = VLASizeMap[VAT]; |
| |
| if (!SizeEntry) { |
| // Get the element size; |
| llvm::Value *ElemSize; |
| |
| QualType ElemTy = VAT->getElementType(); |
| |
| if (ElemTy->isVariableArrayType()) |
| ElemSize = EmitVLASize(ElemTy); |
| else { |
| // FIXME: We use Int32Ty here because the alloca instruction takes a |
| // 32-bit integer. What should we do about overflow? |
| ElemSize = llvm::ConstantInt::get(llvm::Type::Int32Ty, |
| getContext().getTypeSize(ElemTy) / 8); |
| } |
| |
| llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr()); |
| |
| SizeEntry = Builder.CreateMul(ElemSize, NumElements); |
| } |
| |
| return SizeEntry; |
| } else if (const PointerType *PT = Ty->getAsPointerType()) |
| EmitVLASize(PT->getPointeeType()); |
| else { |
| assert(0 && "unknown VM type!"); |
| } |
| |
| return 0; |
| } |
| |
| llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) { |
| if (CGM.getContext().getBuiltinVaListType()->isArrayType()) { |
| return EmitScalarExpr(E); |
| } |
| return EmitLValue(E).getAddress(); |
| } |