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347f7eabb9ae43482f04855cde43f9d164b7b6f0
clang-p2996/clang/lib/CodeGen/CGExprConstant.cpp
Douglas Gregor 347f7eabb9 Code generation support for C99 designated initializers. 
The approach I've taken in this patch is relatively straightforward,
although the code itself is non-trivial. Essentially, as we process
an initializer list we build up a fully-explicit representation of the
initializer list, where each of the subobject initializations occurs
in order. Designators serve to "fill in" subobject initializations in
a non-linear way. The fully-explicit representation makes initializer
lists (both with and without designators) easy to grok for codegen and
later semantic analyses. We keep the syntactic form of the initializer
list linked into the AST for those clients interested in exactly what
the user wrote.

Known limitations:
  - Designating a member of a union that isn't the first member may
    result in bogus initialization (we warn about this)
  - GNU array-range designators are not supported (we warn about this)

llvm-svn: 63242
2009-01-28 21:54:33 +00:00

667 lines
25 KiB
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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 "CGObjCRuntime.h"
#include "clang/AST/APValue.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<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.ErrorUnsupported(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());
}
llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
return Visit(E->getInitializer());
}
llvm::Constant *VisitCastExpr(CastExpr* E) {
// GCC cast to union extension
if (E->getType()->isUnionType()) {
const llvm::Type *Ty = ConvertType(E->getType());
return EmitUnion(CGM.EmitConstantExpr(E->getSubExpr(), CGF), Ty);
}
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()->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 = CGM.EmitConstantExpr(ILE->getInit(i), CGF);
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 = CGM.EmitConstantExpr(E, CGF);
llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C);
if (!CI) {
CGM.ErrorUnsupported(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<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;
for (RecordDecl::field_iterator Field = RD->field_begin(),
FieldEnd = RD->field_end();
EltNo < ILE->getNumInits() && Field != FieldEnd; ++Field) {
FieldNo++;
if (!Field->getIdentifier())
continue;
if (Field->isBitField()) {
InsertBitfieldIntoStruct(Elts, *Field, ILE->getInit(EltNo));
} else {
unsigned FieldNo = CGM.getTypes().getLLVMFieldNo(*Field);
llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(EltNo), CGF);
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 *EmitUnion(llvm::Constant *C, const llvm::Type *Ty) {
// 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 *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
// FIXME: C99 designated initializers won't always initialize the
// first field
int FieldNo = 0; // Field no in RecordDecl
FieldDecl* curField = 0;
for (RecordDecl::field_iterator Field = RD->field_begin(),
FieldEnd = RD->field_end();
Field != FieldEnd; ++Field) {
curField = *Field;
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().getTypePaddedSize(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);
}
return EmitUnion(CGM.EmitConstantExpr(ILE->getInit(0), CGF), Ty);
}
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 = CGM.EmitConstantExpr(ILE->getInit(i), CGF);
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 CGM.EmitConstantExpr(ILE->getInit(0), CGF);
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 *VisitUnaryExtension(const UnaryOperator *E) {
return Visit(E->getSubExpr());
}
// 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<llvm::PointerType>(DstTy)) {
// 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<llvm::PointerType>(Src->getType())) {
// 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)) {
assert((cast<llvm::VectorType>(DstTy)->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);
}
public:
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:
case Expr::QualifiedDeclRefExprClass: {
NamedDecl *Decl = cast<DeclRefExpr>(E)->getDecl();
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl))
return CGM.GetAddrOfFunction(FD);
if (const VarDecl* VD = dyn_cast<VarDecl>(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<MemberExpr>(E);
llvm::Constant *Base;
if (ME->isArrow())
Base = Visit(ME->getBase());
else
Base = EmitLValue(ME->getBase());
FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
// FIXME: Handle other kinds of member expressions.
assert(Field && "No code generation for non-field member expressions");
unsigned FieldNumber = CGM.getTypes().getLLVMFieldNo(Field);
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:
return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E));
case Expr::ObjCStringLiteralClass: {
ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E);
std::string S(SL->getString()->getStrData(),
SL->getString()->getByteLength());
llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(S);
return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
}
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;
}
case Expr::PredefinedExprClass: {
// __func__/__FUNCTION__ -> "". __PRETTY_FUNCTION__ -> "top level".
std::string Str;
if (cast<PredefinedExpr>(E)->getIdentType() ==
PredefinedExpr::PrettyFunction)
Str = "top level";
return CGM.GetAddrOfConstantCString(Str, ".tmp");
}
case Expr::AddrLabelExprClass: {
assert(CGF && "Invalid address of label expression outside function.");
unsigned id = CGF->GetIDForAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel());
llvm::Constant *C = llvm::ConstantInt::get(llvm::Type::Int32Ty, id);
return llvm::ConstantExpr::getIntToPtr(C, ConvertType(E->getType()));
}
case Expr::CallExprClass: {
CallExpr* CE = cast<CallExpr>(E);
if (CE->isBuiltinCall() != Builtin::BI__builtin___CFStringMakeConstantString)
break;
const Expr *Arg = CE->getArg(0)->IgnoreParenCasts();
const StringLiteral *Literal = cast<StringLiteral>(Arg);
std::string S(Literal->getStrData(), Literal->getByteLength());
return CGM.GetAddrOfConstantCFString(S);
}
}
CGM.ErrorUnsupported(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());
Expr::EvalResult Result;
if (E->Evaluate(Result, Context)) {
assert(!Result.HasSideEffects &&
"Constant expr should not have any side effects!");
switch (Result.Val.getKind()) {
default: assert(0 && "unhandled value kind!");
case APValue::LValue: {
llvm::Constant *Offset =
llvm::ConstantInt::get(llvm::Type::Int64Ty,
Result.Val.getLValueOffset());
if (const Expr *LVBase = Result.Val.getLValueBase()) {
llvm::Constant *C =
ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase));
const llvm::Type *Type =
llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
const llvm::Type *DestType = getTypes().ConvertTypeForMem(E->getType());
// FIXME: It's a little ugly that we need to cast to a pointer,
// apply the GEP and then cast back.
C = llvm::ConstantExpr::getBitCast(C, Type);
C = llvm::ConstantExpr::getGetElementPtr(C, &Offset, 1);
return llvm::ConstantExpr::getBitCast(C, DestType);
}
return llvm::ConstantExpr::getIntToPtr(Offset,
getTypes().ConvertType(type));
}
case APValue::Int: {
llvm::Constant *C = llvm::ConstantInt::get(Result.Val.getInt());
if (C->getType() == llvm::Type::Int1Ty) {
const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
C = llvm::ConstantExpr::getZExt(C, BoolTy);
}
return C;
}
case APValue::Float:
return llvm::ConstantFP::get(Result.Val.getFloat());
case APValue::ComplexFloat: {
llvm::Constant *Complex[2];
Complex[0] = llvm::ConstantFP::get(Result.Val.getComplexFloatReal());
Complex[1] = llvm::ConstantFP::get(Result.Val.getComplexFloatImag());
return llvm::ConstantStruct::get(Complex, 2);
}
case APValue::Vector: {
llvm::SmallVector<llvm::Constant *, 4> Inits;
unsigned NumElts = Result.Val.getVectorLength();
for (unsigned i = 0; i != NumElts; ++i) {
APValue &Elt = Result.Val.getVectorElt(i);
if (Elt.isInt())
Inits.push_back(llvm::ConstantInt::get(Elt.getInt()));
else
Inits.push_back(llvm::ConstantFP::get(Elt.getFloat()));
}
return llvm::ConstantVector::get(&Inits[0], Inits.size());
}
}
}
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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