craig.topper added inline comments.
================
Comment at: clang/lib/AST/ExprConstant.cpp:2915
case BO_EQ:
- Result = (LHSValue == RHSValue);
+ Result = -(LHSValue == RHSValue);
break;
----------------
craig.topper wrote:
> erichkeane wrote:
> > efriedma wrote:
> > > Using "operator=" to assign an int to an APInt is going to lead to
> > > weird/confusing results. For example, I think this produces the wrong
> > > result if you have an int128_t vector.
> > Can you clarify your comment? The result type of one of these compare-ops
> > is either an i8 or an i32 I think, so I would expect it to 'just work',
> > right?
> >
> > What problem of operator= on an APInt gives the wrong result? I guess I've
> > never seen/don't know how to repro what you mean.
> >
> > I DID try to get a test wtih a 'compare op' on an __int128 vector, but that
> > ends up asserting in GetSignedVectorType
> Don't compare ops produce a result with the same number of bits as the input?
> If the compare is a vector of int128 the result should also be a vector of
> int128. APInt::operator= takes a uint64_t as input and will zero extend it to
> 128 bits. I think we want to sign extend here.
>
> I assume the APInt for result already been given its bit width before this
> call?
The easy fix is probably just to do the assignment like it was before and then
do `Result.negate()`.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D115670/new/
https://reviews.llvm.org/D115670
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