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Add IRGen support for non-constant OffsetOfExpr. 

llvm-svn: 110326
This commit is contained in:
Eli Friedman 2010-08-05 09:58:49 +00:00
parent 7f76d11dcc
commit d7c7232a1d
1 changed files with 90 additions and 14 deletions
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104
clang/lib/CodeGen/CGExprScalar.cpp
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@ -137,7 +137,7 @@ public:
CGF.getContext().typesAreCompatible(
E->getArgType1(), E->getArgType2()));
}
Value *VisitOffsetOfExpr(const OffsetOfExpr *E);
Value *VisitOffsetOfExpr(OffsetOfExpr *E);
Value *VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E);
Value *VisitAddrLabelExpr(const AddrLabelExpr *E) {
llvm::Value *V = CGF.GetAddrOfLabel(E->getLabel());
@ -1264,19 +1264,95 @@ Value *ScalarExprEmitter::VisitUnaryLNot(const UnaryOperator *E) {
return Builder.CreateZExt(BoolVal, ConvertType(E->getType()), "lnot.ext");
}
Value *ScalarExprEmitter::VisitOffsetOfExpr(const OffsetOfExpr *E) {
Expr::EvalResult Result;
if(E->Evaluate(Result, CGF.getContext()))
return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
// FIXME: Cannot support code generation for non-constant offsetof.
unsigned DiagID = CGF.CGM.getDiags().getCustomDiagID(Diagnostic::Error,
"cannot compile non-constant __builtin_offsetof");
CGF.CGM.getDiags().Report(CGF.getContext().getFullLoc(E->getLocStart()),
DiagID)
<< E->getSourceRange();
return llvm::Constant::getNullValue(ConvertType(E->getType()));
Value *ScalarExprEmitter::VisitOffsetOfExpr(OffsetOfExpr *E) {
// Try folding the offsetof to a constant.
Expr::EvalResult EvalResult;
if (E->Evaluate(EvalResult, CGF.getContext()))
return llvm::ConstantInt::get(VMContext, EvalResult.Val.getInt());
// Loop over the components of the offsetof to compute the value.
unsigned n = E->getNumComponents();
const llvm::Type* ResultType = ConvertType(E->getType());
llvm::Value* Result = llvm::Constant::getNullValue(ResultType);
QualType CurrentType = E->getTypeSourceInfo()->getType();
for (unsigned i = 0; i != n; ++i) {
OffsetOfExpr::OffsetOfNode ON = E->getComponent(i);
llvm::Value *Offset;
switch (ON.getKind()) {
case OffsetOfExpr::OffsetOfNode::Array: {
// Compute the index
Expr *IdxExpr = E->getIndexExpr(ON.getArrayExprIndex());
llvm::Value* Idx = CGF.EmitScalarExpr(IdxExpr);
bool IdxSigned = IdxExpr->getType()->isSignedIntegerType();
Idx = Builder.CreateIntCast(Idx, ResultType, IdxSigned, "conv");
// Save the element type
CurrentType =
CGF.getContext().getAsArrayType(CurrentType)->getElementType();
// Compute the element size
llvm::Value* ElemSize = llvm::ConstantInt::get(ResultType,
CGF.getContext().getTypeSizeInChars(CurrentType).getQuantity());
// Multiply out to compute the result
Offset = Builder.CreateMul(Idx, ElemSize);
break;
}
case OffsetOfExpr::OffsetOfNode::Field: {
FieldDecl *MemberDecl = ON.getField();
RecordDecl *RD = CurrentType->getAs<RecordType>()->getDecl();
const ASTRecordLayout &RL = CGF.getContext().getASTRecordLayout(RD);
// Compute the index of the field in its parent.
unsigned i = 0;
// FIXME: It would be nice if we didn't have to loop here!
for (RecordDecl::field_iterator Field = RD->field_begin(),
FieldEnd = RD->field_end();
Field != FieldEnd; (void)++Field, ++i) {
if (*Field == MemberDecl)
break;
}
assert(i < RL.getFieldCount() && "offsetof field in wrong type");
// Compute the offset to the field
int64_t OffsetInt = RL.getFieldOffset(i) /
CGF.getContext().getCharWidth();
Offset = llvm::ConstantInt::get(ResultType, OffsetInt);
// Save the element type.
CurrentType = MemberDecl->getType();
break;
}
case OffsetOfExpr::OffsetOfNode::Identifier:
assert(0 && "Invalid offsetof");
break;
case OffsetOfExpr::OffsetOfNode::Base: {
if (ON.getBase()->isVirtual()) {
CGF.ErrorUnsupported(E, "virtual base in offsetof");
continue;
}
RecordDecl *RD = CurrentType->getAs<RecordType>()->getDecl();
const ASTRecordLayout &RL = CGF.getContext().getASTRecordLayout(RD);
// Save the element type.
CurrentType = ON.getBase()->getType();
// Compute the offset to the base.
const RecordType *BaseRT = CurrentType->getAs<RecordType>();
CXXRecordDecl *BaseRD = cast<CXXRecordDecl>(BaseRT->getDecl());
int64_t OffsetInt = RL.getBaseClassOffset(BaseRD) /
CGF.getContext().getCharWidth();
Offset = llvm::ConstantInt::get(ResultType, OffsetInt);
break;
}
}
Result = Builder.CreateAdd(Result, Offset);
}
return Result;
}
/// VisitSizeOfAlignOfExpr - Return the size or alignment of the type of