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* Implement more powerful expr analysis of cast instructions

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1335 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2001-11-26 16:53:50 +00:00
parent 0252755825
commit 882572aa68
1 changed files with 19 additions and 10 deletions
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29
lib/Analysis/Expressions.cpp
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@ -284,21 +284,30 @@ ExprType analysis::ClassifyExpression(Value *Expr) {
case Instruction::Cast: {
ExprType Src(ClassifyExpression(I->getOperand(0)));
if (Src.ExprTy != ExprType::Constant)
return I;
const ConstPoolInt *Offs = Src.Offset;
if (Offs == 0) return ExprType();
const Type *DestTy = I->getType();
if (DestTy->isPointerType())
DestTy = Type::ULongTy; // Pointer types are represented as ulong
assert(DestTy->isIntegral() && "Can only handle integral types!");
/*
if (!Src.getExprType(0)->isLosslesslyConvertableTo(DestTy)) {
if (Src.ExprTy != ExprType::Constant)
return I; // Converting cast, and not a constant value...
}
*/
const ConstPoolVal *CPV =ConstRules::get(*Offs)->castTo(Offs, DestTy);
if (!CPV) return I;
assert(CPV->getType()->isIntegral() && "Must have an integral type!");
return cast<ConstPoolInt>(CPV);
const ConstPoolInt *Offset = Src.Offset;
const ConstPoolInt *Scale = Src.Scale;
if (Offset) {
const ConstPoolVal *CPV = ConstantFoldCastInstruction(Offset, DestTy);
if (!CPV) return I;
Offset = cast<ConstPoolInt>(CPV);
}
if (Scale) {
const ConstPoolVal *CPV = ConstantFoldCastInstruction(Scale, DestTy);
if (!CPV) return I;
Scale = cast<ConstPoolInt>(CPV);
}
return ExprType(Scale, Src.Var, Offset);
} // end case Instruction::Cast
// TODO: Handle SUB, SHR?