//===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This contains code to emit Constant Expr nodes as LLVM code. // //===----------------------------------------------------------------------===// #include "CodeGenFunction.h" #include "CodeGenModule.h" #include "CGObjCRuntime.h" #include "clang/AST/ASTContext.h" #include "clang/AST/StmtVisitor.h" #include "llvm/Constants.h" #include "llvm/Function.h" #include "llvm/GlobalVariable.h" #include "llvm/Support/Compiler.h" #include "llvm/Target/TargetData.h" using namespace clang; using namespace CodeGen; namespace { class VISIBILITY_HIDDEN ConstExprEmitter : public StmtVisitor { CodeGenModule &CGM; CodeGenFunction *CGF; public: ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) : CGM(cgm), CGF(cgf) { } //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// llvm::Constant *VisitStmt(Stmt *S) { CGM.WarnUnsupported(S, "constant expression"); QualType T = cast(S)->getType(); return llvm::UndefValue::get(CGM.getTypes().ConvertType(T)); } llvm::Constant *VisitParenExpr(ParenExpr *PE) { return Visit(PE->getSubExpr()); } // Leaves llvm::Constant *VisitIntegerLiteral(const IntegerLiteral *E) { return llvm::ConstantInt::get(E->getValue()); } llvm::Constant *VisitFloatingLiteral(const FloatingLiteral *E) { return llvm::ConstantFP::get(E->getValue()); } llvm::Constant *VisitCharacterLiteral(const CharacterLiteral *E) { return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue()); } llvm::Constant *VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue()); } llvm::Constant *VisitObjCStringLiteral(const ObjCStringLiteral *E) { std::string S(E->getString()->getStrData(), E->getString()->getByteLength()); llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(S); return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); } llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { return Visit(E->getInitializer()); } llvm::Constant *VisitCastExpr(const CastExpr* E) { llvm::Constant *C = Visit(E->getSubExpr()); return EmitConversion(C, E->getSubExpr()->getType(), E->getType()); } llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { return Visit(DAE->getExpr()); } llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { std::vector Elts; const llvm::ArrayType *AType = cast(ConvertType(ILE->getType())); unsigned NumInitElements = ILE->getNumInits(); // FIXME: Check for wide strings if (NumInitElements > 0 && isa(ILE->getInit(0)) && ILE->getType()->getArrayElementTypeNoTypeQual()->isCharType()) return Visit(ILE->getInit(0)); const llvm::Type *ElemTy = AType->getElementType(); unsigned NumElements = AType->getNumElements(); // Initialising an array requires us to automatically // initialise any elements that have not been initialised explicitly unsigned NumInitableElts = std::min(NumInitElements, NumElements); // Copy initializer elements. unsigned i = 0; bool RewriteType = false; for (; i < NumInitableElts; ++i) { llvm::Constant *C = Visit(ILE->getInit(i)); RewriteType |= (C->getType() != ElemTy); Elts.push_back(C); } // Initialize remaining array elements. for (; i < NumElements; ++i) Elts.push_back(llvm::Constant::getNullValue(ElemTy)); if (RewriteType) { // FIXME: Try to avoid packing the array std::vector Types; for (unsigned i = 0; i < Elts.size(); ++i) Types.push_back(Elts[i]->getType()); const llvm::StructType *SType = llvm::StructType::get(Types, true); return llvm::ConstantStruct::get(SType, Elts); } return llvm::ConstantArray::get(AType, Elts); } void InsertBitfieldIntoStruct(std::vector& Elts, FieldDecl* Field, Expr* E) { // Calculate the value to insert llvm::Constant *C = Visit(E); llvm::ConstantInt *CI = dyn_cast(C); if (!CI) { CGM.WarnUnsupported(E, "bitfield initialization"); return; } llvm::APInt V = CI->getValue(); // Calculate information about the relevant field const llvm::Type* Ty = CI->getType(); const llvm::TargetData &TD = CGM.getTypes().getTargetData(); unsigned size = TD.getTypeStoreSizeInBits(Ty); unsigned fieldOffset = CGM.getTypes().getLLVMFieldNo(Field) * size; CodeGenTypes::BitFieldInfo bitFieldInfo = CGM.getTypes().getBitFieldInfo(Field); fieldOffset += bitFieldInfo.Begin; // Find where to start the insertion // FIXME: This is O(n^2) in the number of bit-fields! // FIXME: This won't work if the struct isn't completely packed! unsigned offset = 0, i = 0; while (offset < (fieldOffset & -8)) offset += TD.getTypeStoreSizeInBits(Elts[i++]->getType()); // Advance over 0 sized elements (must terminate in bounds since // the bitfield must have a size). while (TD.getTypeStoreSizeInBits(Elts[i]->getType()) == 0) ++i; // Promote the size of V if necessary // FIXME: This should never occur, but currently it can because // initializer constants are cast to bool, and because clang is // not enforcing bitfield width limits. if (bitFieldInfo.Size > V.getBitWidth()) V.zext(bitFieldInfo.Size); // Insert the bits into the struct // FIXME: This algorthm is only correct on X86! // FIXME: THis algorthm assumes bit-fields only have byte-size elements! unsigned bitsToInsert = bitFieldInfo.Size; unsigned curBits = std::min(8 - (fieldOffset & 7), bitsToInsert); unsigned byte = V.getLoBits(curBits).getZExtValue() << (fieldOffset & 7); do { llvm::Constant* byteC = llvm::ConstantInt::get(llvm::Type::Int8Ty, byte); Elts[i] = llvm::ConstantExpr::getOr(Elts[i], byteC); ++i; V = V.lshr(curBits); bitsToInsert -= curBits; if (!bitsToInsert) break; curBits = bitsToInsert > 8 ? 8 : bitsToInsert; byte = V.getLoBits(curBits).getZExtValue(); } while (true); } llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { const llvm::StructType *SType = cast(ConvertType(ILE->getType())); RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl(); std::vector Elts; // Initialize the whole structure to zero. for (unsigned i = 0; i < SType->getNumElements(); ++i) { const llvm::Type *FieldTy = SType->getElementType(i); Elts.push_back(llvm::Constant::getNullValue(FieldTy)); } // Copy initializer elements. Skip padding fields. unsigned EltNo = 0; // Element no in ILE int FieldNo = 0; // Field no in RecordDecl bool RewriteType = false; while (EltNo < ILE->getNumInits() && FieldNo < RD->getNumMembers()) { FieldDecl* curField = RD->getMember(FieldNo); FieldNo++; if (!curField->getIdentifier()) continue; if (curField->isBitField()) { InsertBitfieldIntoStruct(Elts, curField, ILE->getInit(EltNo)); } else { unsigned FieldNo = CGM.getTypes().getLLVMFieldNo(curField); llvm::Constant* C = Visit(ILE->getInit(EltNo)); RewriteType |= (C->getType() != Elts[FieldNo]->getType()); Elts[FieldNo] = C; } EltNo++; } if (RewriteType) { // FIXME: Make this work for non-packed structs assert(SType->isPacked() && "Cannot recreate unpacked structs"); std::vector Types; for (unsigned i = 0; i < Elts.size(); ++i) Types.push_back(Elts[i]->getType()); SType = llvm::StructType::get(Types, true); } return llvm::ConstantStruct::get(SType, Elts); } llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl(); const llvm::Type *Ty = ConvertType(ILE->getType()); // Find the field decl we're initializing, if any int FieldNo = 0; // Field no in RecordDecl FieldDecl* curField = 0; while (FieldNo < RD->getNumMembers()) { curField = RD->getMember(FieldNo); FieldNo++; if (curField->getIdentifier()) break; } if (!curField || !curField->getIdentifier() || ILE->getNumInits() == 0) return llvm::Constant::getNullValue(Ty); if (curField->isBitField()) { // Create a dummy struct for bit-field insertion unsigned NumElts = CGM.getTargetData().getABITypeSize(Ty) / 8; llvm::Constant* NV = llvm::Constant::getNullValue(llvm::Type::Int8Ty); std::vector Elts(NumElts, NV); InsertBitfieldIntoStruct(Elts, curField, ILE->getInit(0)); const llvm::ArrayType *RetTy = llvm::ArrayType::get(NV->getType(), NumElts); return llvm::ConstantArray::get(RetTy, Elts); } llvm::Constant *C = Visit(ILE->getInit(0)); // Build a struct with the union sub-element as the first member, // and padded to the appropriate size std::vector Elts; std::vector Types; Elts.push_back(C); Types.push_back(C->getType()); unsigned CurSize = CGM.getTargetData().getTypeStoreSize(C->getType()); unsigned TotalSize = CGM.getTargetData().getTypeStoreSize(Ty); while (CurSize < TotalSize) { Elts.push_back(llvm::Constant::getNullValue(llvm::Type::Int8Ty)); Types.push_back(llvm::Type::Int8Ty); CurSize++; } // This always generates a packed struct // FIXME: Try to generate an unpacked struct when we can llvm::StructType* STy = llvm::StructType::get(Types, true); return llvm::ConstantStruct::get(STy, Elts); } llvm::Constant *EmitVectorInitialization(InitListExpr *ILE) { const llvm::VectorType *VType = cast(ConvertType(ILE->getType())); const llvm::Type *ElemTy = VType->getElementType(); std::vector Elts; unsigned NumElements = VType->getNumElements(); unsigned NumInitElements = ILE->getNumInits(); unsigned NumInitableElts = std::min(NumInitElements, NumElements); // Copy initializer elements. unsigned i = 0; for (; i < NumInitableElts; ++i) { llvm::Constant *C = Visit(ILE->getInit(i)); Elts.push_back(C); } for (; i < NumElements; ++i) Elts.push_back(llvm::Constant::getNullValue(ElemTy)); return llvm::ConstantVector::get(VType, Elts); } llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { if (ILE->getType()->isScalarType()) { // We have a scalar in braces. Just use the first element. if (ILE->getNumInits() > 0) return Visit(ILE->getInit(0)); const llvm::Type* RetTy = CGM.getTypes().ConvertType(ILE->getType()); return llvm::Constant::getNullValue(RetTy); } if (ILE->getType()->isArrayType()) return EmitArrayInitialization(ILE); if (ILE->getType()->isStructureType()) return EmitStructInitialization(ILE); if (ILE->getType()->isUnionType()) return EmitUnionInitialization(ILE); if (ILE->getType()->isVectorType()) return EmitVectorInitialization(ILE); assert(0 && "Unable to handle InitListExpr"); // Get rid of control reaches end of void function warning. // Not reached. return 0; } llvm::Constant *VisitImplicitCastExpr(ImplicitCastExpr *ICExpr) { Expr* SExpr = ICExpr->getSubExpr(); QualType SType = SExpr->getType(); llvm::Constant *C; // the intermediate expression QualType T; // the type of the intermediate expression if (SType->isArrayType()) { // Arrays decay to a pointer to the first element // VLAs would require special handling, but they can't occur here C = EmitLValue(SExpr); llvm::Constant *Idx0 = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); llvm::Constant *Ops[] = {Idx0, Idx0}; C = llvm::ConstantExpr::getGetElementPtr(C, Ops, 2); T = CGM.getContext().getArrayDecayedType(SType); } else if (SType->isFunctionType()) { // Function types decay to a pointer to the function C = EmitLValue(SExpr); T = CGM.getContext().getPointerType(SType); } else { C = Visit(SExpr); T = SType; } // Perform the conversion; note that an implicit cast can both promote // and convert an array/function return EmitConversion(C, T, ICExpr->getType()); } llvm::Constant *VisitStringLiteral(StringLiteral *E) { assert(!E->getType()->isPointerType() && "Strings are always arrays"); // Otherwise this must be a string initializing an array in a static // initializer. Don't emit it as the address of the string, emit the string // data itself as an inline array. return llvm::ConstantArray::get(CGM.GetStringForStringLiteral(E), false); } llvm::Constant *VisitDeclRefExpr(DeclRefExpr *E) { const ValueDecl *Decl = E->getDecl(); if (const EnumConstantDecl *EC = dyn_cast(Decl)) return llvm::ConstantInt::get(EC->getInitVal()); assert(0 && "Unsupported decl ref type!"); return 0; } llvm::Constant *VisitSizeOfAlignOfTypeExpr(const SizeOfAlignOfTypeExpr *E) { return EmitSizeAlignOf(E->getArgumentType(), E->getType(), E->isSizeOf()); } // Unary operators llvm::Constant *VisitUnaryPlus(const UnaryOperator *E) { return Visit(E->getSubExpr()); } llvm::Constant *VisitUnaryMinus(const UnaryOperator *E) { return llvm::ConstantExpr::getNeg(Visit(E->getSubExpr())); } llvm::Constant *VisitUnaryNot(const UnaryOperator *E) { return llvm::ConstantExpr::getNot(Visit(E->getSubExpr())); } llvm::Constant *VisitUnaryLNot(const UnaryOperator *E) { llvm::Constant *SubExpr = Visit(E->getSubExpr()); if (E->getSubExpr()->getType()->isRealFloatingType()) { // Compare against 0.0 for fp scalars. llvm::Constant *Zero = llvm::Constant::getNullValue(SubExpr->getType()); SubExpr = llvm::ConstantExpr::getFCmp(llvm::FCmpInst::FCMP_UEQ, SubExpr, Zero); } else { assert((E->getSubExpr()->getType()->isIntegerType() || E->getSubExpr()->getType()->isPointerType()) && "Unknown scalar type to convert"); // Compare against an integer or pointer null. llvm::Constant *Zero = llvm::Constant::getNullValue(SubExpr->getType()); SubExpr = llvm::ConstantExpr::getICmp(llvm::ICmpInst::ICMP_EQ, SubExpr, Zero); } return llvm::ConstantExpr::getZExt(SubExpr, ConvertType(E->getType())); } llvm::Constant *VisitUnarySizeOf(const UnaryOperator *E) { return EmitSizeAlignOf(E->getSubExpr()->getType(), E->getType(), true); } llvm::Constant *VisitUnaryAlignOf(const UnaryOperator *E) { return EmitSizeAlignOf(E->getSubExpr()->getType(), E->getType(), false); } llvm::Constant *VisitUnaryAddrOf(const UnaryOperator *E) { return EmitLValue(E->getSubExpr()); } llvm::Constant *VisitUnaryOffsetOf(const UnaryOperator *E) { int64_t Val = E->evaluateOffsetOf(CGM.getContext()); assert(E->getType()->isIntegerType() && "Result type must be an integer!"); uint32_t ResultWidth = static_cast(CGM.getContext().getTypeSize(E->getType())); return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Val)); } llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { return Visit(E->getSubExpr()); } // Binary operators llvm::Constant *VisitBinOr(const BinaryOperator *E) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); return llvm::ConstantExpr::getOr(LHS, RHS); } llvm::Constant *VisitBinSub(const BinaryOperator *E) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); if (!isa(RHS->getType())) { // pointer - int if (isa(LHS->getType())) { llvm::Constant *Idx = llvm::ConstantExpr::getNeg(RHS); return llvm::ConstantExpr::getGetElementPtr(LHS, &Idx, 1); } // int - int return llvm::ConstantExpr::getSub(LHS, RHS); } assert(isa(LHS->getType())); const llvm::Type *ResultType = ConvertType(E->getType()); const QualType Type = E->getLHS()->getType(); const QualType ElementType = Type->getAsPointerType()->getPointeeType(); LHS = llvm::ConstantExpr::getPtrToInt(LHS, ResultType); RHS = llvm::ConstantExpr::getPtrToInt(RHS, ResultType); llvm::Constant *sub = llvm::ConstantExpr::getSub(LHS, RHS); llvm::Constant *size = EmitSizeAlignOf(ElementType, E->getType(), true); return llvm::ConstantExpr::getSDiv(sub, size); } llvm::Constant *VisitBinShl(const BinaryOperator *E) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); // LLVM requires the LHS and RHS to be the same type: promote or truncate the // RHS to the same size as the LHS. if (LHS->getType() != RHS->getType()) RHS = llvm::ConstantExpr::getIntegerCast(RHS, LHS->getType(), false); return llvm::ConstantExpr::getShl(LHS, RHS); } llvm::Constant *VisitBinMul(const BinaryOperator *E) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); return llvm::ConstantExpr::getMul(LHS, RHS); } llvm::Constant *VisitBinDiv(const BinaryOperator *E) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); if (LHS->getType()->isFPOrFPVector()) return llvm::ConstantExpr::getFDiv(LHS, RHS); else if (E->getType()->isUnsignedIntegerType()) return llvm::ConstantExpr::getUDiv(LHS, RHS); else return llvm::ConstantExpr::getSDiv(LHS, RHS); } llvm::Constant *VisitBinAdd(const BinaryOperator *E) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); if (!E->getType()->isPointerType()) return llvm::ConstantExpr::getAdd(LHS, RHS); llvm::Constant *Ptr, *Idx; if (isa(LHS->getType())) { // pointer + int Ptr = LHS; Idx = RHS; } else { // int + pointer Ptr = RHS; Idx = LHS; } return llvm::ConstantExpr::getGetElementPtr(Ptr, &Idx, 1); } llvm::Constant *VisitBinAnd(const BinaryOperator *E) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); return llvm::ConstantExpr::getAnd(LHS, RHS); } llvm::Constant *EmitCmp(const BinaryOperator *E, llvm::CmpInst::Predicate SignedPred, llvm::CmpInst::Predicate UnsignedPred, llvm::CmpInst::Predicate FloatPred) { llvm::Constant *LHS = Visit(E->getLHS()); llvm::Constant *RHS = Visit(E->getRHS()); llvm::Constant *Result; if (LHS->getType()->isInteger() || isa(LHS->getType())) { if (E->getLHS()->getType()->isSignedIntegerType()) Result = llvm::ConstantExpr::getICmp(SignedPred, LHS, RHS); else Result = llvm::ConstantExpr::getICmp(UnsignedPred, LHS, RHS); } else if (LHS->getType()->isFloatingPoint()) { Result = llvm::ConstantExpr::getFCmp(FloatPred, LHS, RHS); } else { CGM.WarnUnsupported(E, "constant expression"); Result = llvm::ConstantInt::getFalse(); } const llvm::Type* ResultType = ConvertType(E->getType()); return llvm::ConstantExpr::getZExtOrBitCast(Result, ResultType); } llvm::Constant *VisitBinNE(const BinaryOperator *E) { return EmitCmp(E, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_NE, llvm::CmpInst::FCMP_ONE); } llvm::Constant *VisitBinEQ(const BinaryOperator *E) { return EmitCmp(E, llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_EQ, llvm::CmpInst::FCMP_OEQ); } llvm::Constant *VisitBinLT(const BinaryOperator *E) { return EmitCmp(E, llvm::CmpInst::ICMP_SLT, llvm::CmpInst::ICMP_ULT, llvm::CmpInst::FCMP_OLT); } llvm::Constant *VisitBinLE(const BinaryOperator *E) { return EmitCmp(E, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::FCMP_OLE); } llvm::Constant *VisitBinGT(const BinaryOperator *E) { return EmitCmp(E, llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::FCMP_OGT); } llvm::Constant *VisitBinGE(const BinaryOperator *E) { return EmitCmp(E, llvm::CmpInst::ICMP_SGE, llvm::CmpInst::ICMP_SGE, llvm::CmpInst::FCMP_OGE); } llvm::Constant *VisitConditionalOperator(const ConditionalOperator *E) { llvm::Constant *Cond = Visit(E->getCond()); llvm::Constant *CondVal = EmitConversionToBool(Cond, E->getType()); llvm::ConstantInt *CondValInt = dyn_cast(CondVal); if (!CondValInt) { CGM.WarnUnsupported(E, "constant expression"); return llvm::Constant::getNullValue(ConvertType(E->getType())); } if (CondValInt->isOne()) { if (E->getLHS()) return Visit(E->getLHS()); return Cond; } return Visit(E->getRHS()); } // Utility methods const llvm::Type *ConvertType(QualType T) { return CGM.getTypes().ConvertType(T); } llvm::Constant *EmitConversionToBool(llvm::Constant *Src, QualType SrcType) { assert(SrcType->isCanonical() && "EmitConversion strips typedefs"); if (SrcType->isRealFloatingType()) { // Compare against 0.0 for fp scalars. llvm::Constant *Zero = llvm::Constant::getNullValue(Src->getType()); return llvm::ConstantExpr::getFCmp(llvm::FCmpInst::FCMP_UNE, Src, Zero); } assert((SrcType->isIntegerType() || SrcType->isPointerType()) && "Unknown scalar type to convert"); // Compare against an integer or pointer null. llvm::Constant *Zero = llvm::Constant::getNullValue(Src->getType()); return llvm::ConstantExpr::getICmp(llvm::ICmpInst::ICMP_NE, Src, Zero); } llvm::Constant *EmitConversion(llvm::Constant *Src, QualType SrcType, QualType DstType) { SrcType = CGM.getContext().getCanonicalType(SrcType); DstType = CGM.getContext().getCanonicalType(DstType); if (SrcType == DstType) return Src; // Handle conversions to bool first, they are special: comparisons against 0. if (DstType->isBooleanType()) return EmitConversionToBool(Src, SrcType); const llvm::Type *DstTy = ConvertType(DstType); // Ignore conversions like int -> uint. if (Src->getType() == DstTy) return Src; // Handle pointer conversions next: pointers can only be converted to/from // other pointers and integers. if (isa(DstTy)) { // The source value may be an integer, or a pointer. if (isa(Src->getType())) return llvm::ConstantExpr::getBitCast(Src, DstTy); assert(SrcType->isIntegerType() &&"Not ptr->ptr or int->ptr conversion?"); return llvm::ConstantExpr::getIntToPtr(Src, DstTy); } if (isa(Src->getType())) { // Must be an ptr to int cast. assert(isa(DstTy) && "not ptr->int?"); return llvm::ConstantExpr::getPtrToInt(Src, DstTy); } // A scalar source can be splatted to a vector of the same element type if (isa(DstTy) && !isa(SrcType)) { const llvm::VectorType *VT = cast(DstTy); assert((VT->getElementType() == Src->getType()) && "Vector element type must match scalar type to splat."); unsigned NumElements = DstType->getAsVectorType()->getNumElements(); llvm::SmallVector Elements; for (unsigned i = 0; i < NumElements; i++) Elements.push_back(Src); return llvm::ConstantVector::get(&Elements[0], NumElements); } if (isa(Src->getType()) || isa(DstTy)) { return llvm::ConstantExpr::getBitCast(Src, DstTy); } // Finally, we have the arithmetic types: real int/float. if (isa(Src->getType())) { bool InputSigned = SrcType->isSignedIntegerType(); if (isa(DstTy)) return llvm::ConstantExpr::getIntegerCast(Src, DstTy, InputSigned); else if (InputSigned) return llvm::ConstantExpr::getSIToFP(Src, DstTy); else return llvm::ConstantExpr::getUIToFP(Src, DstTy); } assert(Src->getType()->isFloatingPoint() && "Unknown real conversion"); if (isa(DstTy)) { if (DstType->isSignedIntegerType()) return llvm::ConstantExpr::getFPToSI(Src, DstTy); else return llvm::ConstantExpr::getFPToUI(Src, DstTy); } assert(DstTy->isFloatingPoint() && "Unknown real conversion"); if (DstTy->getTypeID() < Src->getType()->getTypeID()) return llvm::ConstantExpr::getFPTrunc(Src, DstTy); else return llvm::ConstantExpr::getFPExtend(Src, DstTy); } llvm::Constant *EmitSizeAlignOf(QualType TypeToSize, QualType RetType, bool isSizeOf) { std::pair Info = CGM.getContext().getTypeInfo(TypeToSize); uint64_t Val = isSizeOf ? Info.first : Info.second; Val /= 8; // Return size in bytes, not bits. assert(RetType->isIntegerType() && "Result type must be an integer!"); uint32_t ResultWidth = static_cast(CGM.getContext().getTypeSize(RetType)); return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Val)); } llvm::Constant *EmitLValue(Expr *E) { switch (E->getStmtClass()) { default: break; case Expr::ParenExprClass: // Elide parenthesis return EmitLValue(cast(E)->getSubExpr()); case Expr::CompoundLiteralExprClass: { // Note that due to the nature of compound literals, this is guaranteed // to be the only use of the variable, so we just generate it here. CompoundLiteralExpr *CLE = cast(E); llvm::Constant* C = Visit(CLE->getInitializer()); C = new llvm::GlobalVariable(C->getType(),E->getType().isConstQualified(), llvm::GlobalValue::InternalLinkage, C, ".compoundliteral", &CGM.getModule()); return C; } case Expr::DeclRefExprClass: { ValueDecl *Decl = cast(E)->getDecl(); if (const FunctionDecl *FD = dyn_cast(Decl)) return CGM.GetAddrOfFunction(FD); if (const VarDecl* VD = dyn_cast(Decl)) { if (VD->isFileVarDecl()) return CGM.GetAddrOfGlobalVar(VD); else if (VD->isBlockVarDecl()) { assert(CGF && "Can't access static local vars without CGF"); return CGF->GetAddrOfStaticLocalVar(VD); } } break; } case Expr::MemberExprClass: { MemberExpr* ME = cast(E); llvm::Constant *Base; if (ME->isArrow()) Base = Visit(ME->getBase()); else Base = EmitLValue(ME->getBase()); unsigned FieldNumber = CGM.getTypes().getLLVMFieldNo(ME->getMemberDecl()); llvm::Constant *Zero = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); llvm::Constant *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, FieldNumber); llvm::Value *Ops[] = {Zero, Idx}; return llvm::ConstantExpr::getGetElementPtr(Base, Ops, 2); } case Expr::ArraySubscriptExprClass: { ArraySubscriptExpr* ASExpr = cast(E); llvm::Constant *Base = Visit(ASExpr->getBase()); llvm::Constant *Index = Visit(ASExpr->getIdx()); assert(!ASExpr->getBase()->getType()->isVectorType() && "Taking the address of a vector component is illegal!"); return llvm::ConstantExpr::getGetElementPtr(Base, &Index, 1); } case Expr::StringLiteralClass: return CGM.GetAddrOfConstantStringFromLiteral(cast(E)); case Expr::UnaryOperatorClass: { UnaryOperator *Exp = cast(E); switch (Exp->getOpcode()) { default: break; case UnaryOperator::Extension: // Extension is just a wrapper for expressions return EmitLValue(Exp->getSubExpr()); case UnaryOperator::Real: case UnaryOperator::Imag: { // The address of __real or __imag is just a GEP off the address // of the internal expression llvm::Constant* C = EmitLValue(Exp->getSubExpr()); llvm::Constant *Zero = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); llvm::Constant *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, Exp->getOpcode() == UnaryOperator::Imag); llvm::Value *Ops[] = {Zero, Idx}; return llvm::ConstantExpr::getGetElementPtr(C, Ops, 2); } case UnaryOperator::Deref: // The address of a deref is just the value of the expression return Visit(Exp->getSubExpr()); } break; } } CGM.WarnUnsupported(E, "constant l-value expression"); llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType())); return llvm::UndefValue::get(Ty); } }; } // end anonymous namespace. llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, CodeGenFunction *CGF) { QualType type = Context.getCanonicalType(E->getType()); if (type->isIntegerType()) { llvm::APSInt Value(static_cast(Context.getTypeSize(type))); if (E->isIntegerConstantExpr(Value, Context)) { return llvm::ConstantInt::get(Value); } } llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast(E)); if (C->getType() == llvm::Type::Int1Ty) { const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); C = llvm::ConstantExpr::getZExt(C, BoolTy); } return C; }