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llvm-project/clang/lib/CodeGen/CGExprConstant.cpp

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//===--- 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 "clang/AST/AST.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<ConstExprEmitter, llvm::Constant*> {
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<Expr>(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 *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<llvm::Constant*> Elts;
const llvm::ArrayType *AType =
cast<llvm::ArrayType>(ConvertType(ILE->getType()));
unsigned NumInitElements = ILE->getNumInits();
// FIXME: Check for wide strings
if (NumInitElements > 0 && isa<StringLiteral>(ILE->getInit(0)) &&
ILE->getType()->getAsArrayType()->getElementType()->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<const llvm::Type*> 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<llvm::Constant*>& Elts,
FieldDecl* Field, Expr* E) {
// Calculate the value to insert
llvm::Constant *C = Visit(E);
llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(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();
unsigned size = CGM.getTypes().getTargetData().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 += CGM.getTypes().getTargetData().getTypeStoreSizeInBits(Elts[i++]->getType());
// 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<llvm::StructType>(ConvertType(ILE->getType()));
RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl();
std::vector<llvm::Constant*> 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<const llvm::Type*> 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<llvm::Constant*> 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<llvm::Constant*> Elts;
std::vector<const llvm::Type*> 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<llvm::VectorType>(ConvertType(ILE->getType()));
const llvm::Type *ElemTy = VType->getElementType();
std::vector<llvm::Constant*> 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);
QualType ElemType = SType->getAsArrayType()->getElementType();
T = CGM.getContext().getPointerType(ElemType);
} 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) {
const char *StrData = E->getStrData();
unsigned Len = E->getByteLength();
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.
const ConstantArrayType *CAT = E->getType()->getAsConstantArrayType();
assert(CAT && "String isn't pointer or array!");
std::string Str(StrData, StrData + Len);
// Null terminate the string before potentially truncating it.
// FIXME: What about wchar_t strings?
Str.push_back(0);
uint64_t RealLen = CAT->getSize().getZExtValue();
// String or grow the initializer to the required size.
if (RealLen != Str.size())
Str.resize(RealLen);
return llvm::ConstantArray::get(Str, false);
}
llvm::Constant *VisitDeclRefExpr(DeclRefExpr *E) {
const ValueDecl *Decl = E->getDecl();
if (const EnumConstantDecl *EC = dyn_cast<EnumConstantDecl>(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<uint32_t>(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<llvm::PointerType>(RHS->getType())) {
// pointer - int
if (isa<llvm::PointerType>(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<llvm::PointerType>(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<llvm::PointerType>(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<llvm::PointerType>(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<llvm::ConstantInt>(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 = SrcType.getCanonicalType();
DstType = DstType.getCanonicalType();
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<PointerType>(DstType)) {
// The source value may be an integer, or a pointer.
if (isa<llvm::PointerType>(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<PointerType>(SrcType)) {
// Must be an ptr to int cast.
assert(isa<llvm::IntegerType>(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<llvm::VectorType>(DstTy) && !isa<VectorType>(SrcType)) {
const llvm::VectorType *VT = cast<llvm::VectorType>(DstTy);
assert((VT->getElementType() == Src->getType()) &&
"Vector element type must match scalar type to splat.");
unsigned NumElements = DstType->getAsVectorType()->getNumElements();
llvm::SmallVector<llvm::Constant*, 16> Elements;
for (unsigned i = 0; i < NumElements; i++)
Elements.push_back(Src);
return llvm::ConstantVector::get(&Elements[0], NumElements);
}
if (isa<llvm::VectorType>(Src->getType()) ||
isa<llvm::VectorType>(DstTy)) {
return llvm::ConstantExpr::getBitCast(Src, DstTy);
}
// Finally, we have the arithmetic types: real int/float.
if (isa<llvm::IntegerType>(Src->getType())) {
bool InputSigned = SrcType->isSignedIntegerType();
if (isa<llvm::IntegerType>(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<llvm::IntegerType>(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<uint64_t, unsigned> 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<uint32_t>(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<ParenExpr>(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<CompoundLiteralExpr>(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<DeclRefExpr>(E)->getDecl();
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl))
return CGM.GetAddrOfFunctionDecl(FD, false);
if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) {
if (VD->isFileVarDecl())
return CGM.GetAddrOfGlobalVar(VD, false);
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<MemberExpr>(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<ArraySubscriptExpr>(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: {
StringLiteral *String = cast<StringLiteral>(E);
assert(!String->isWide() && "Cannot codegen wide strings yet");
const char *StrData = String->getStrData();
unsigned Len = String->getByteLength();
return CGM.GetAddrOfConstantString(std::string(StrData, StrData + Len));
}
case Expr::UnaryOperatorClass: {
UnaryOperator *Exp = cast<UnaryOperator>(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 = E->getType().getCanonicalType();
if (type->isIntegerType()) {
llvm::APSInt Value(static_cast<uint32_t>(Context.getTypeSize(type)));
if (E->isIntegerConstantExpr(Value, Context)) {
return llvm::ConstantInt::get(Value);
}
}
llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
if (C->getType() == llvm::Type::Int1Ty) {
const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
C = llvm::ConstantExpr::getZExt(C, BoolTy);
}
return C;
}
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