On Wed, 2006-12-13 at 09:48 -0800, Chris Lattner wrote:
> >>> @@ -5681,7 +5677,7 @@
> >>> /// evaluate the expression.
> >>> Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type
> >>> *Ty) {
> >>> if (Constant *C = dyn_cast<Constant>(V))
> >>> - return ConstantExpr::getCast(C, Ty);
> >>> + return ConstantExpr::getIntegerCast(C, Ty, C->getType()-
> >>>> isSigned());
> >>
> >> This looks extremely unsafe. Why is it ok?
> >
> > The only place EvaluateInDifferentType is called is from
> > commonIntCastTransforms. Those casts are guaranteed to only involve
> > integer operands. Therefore, the only kind of cast that could be
> > involved is an integer cast.
> >
> > What looks "extremely" unsafe about it?
>
> I'm specifically concerned that there is nothing controlling whether
> a zext or sext gets generated other than C->getType()->isSigned(),
> which I'm not convinced is the right thing. Getting the wrong one is
> bad :)
Ah, okay, that makes sense. I'll look at getting rid of the isSigned()
call.
>
> -Chris
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