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34994cbcbf
teak-llvm/clang/lib/CodeGen/CGExprConstant.cpp
Eli Friedman 34994cbcbf Fix and enable generating general union initializers. Essentially, what 
this does is reconstruct the type for structs and arrays if the type 
wouldn't be compatible otherwise.

The assertion about packing in the struct type reconstruction code 
sucks, but I don't see any obvious way to fix it.  Maybe we need a general
utility method to take a list of types and alignments and try to construct an
unpacked type if possible?

llvm-svn: 51785
2008-05-30 19:58:50 +00:00

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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;
do {
curField = RD->getMember(FieldNo);
FieldNo++;
} while (!curField->getIdentifier() && FieldNo < RD->getNumMembers());
if (ILE->getNumInits() == 0 || !curField->getIdentifier())
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(0 && "Unhandled bin sub case!");
return 0;
}
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);
}
}
return ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
}
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