https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110643
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |MOVED
Status|WAITING |RESOLVED
--- Comment #22 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
template <typename T, size_t N, HWY_IF_FLOAT(T)>
HWY_API Mask128<T, N> IsInf(const Vec128<T, N> v) {
const DFromV<decltype(v)> d;
const RebindToSigned<decltype(d)> di;
const VFromD<decltype(di)> vi = BitCast(di, v);
// 'Shift left' to clear the sign bit, check for exponent=max and mantissa=0.
return RebindMask(d, Eq(Add(vi, vi), Set(di, hwy::MaxExponentTimes2<T>())));
}
Most likely should have been:
```
template <typename T, size_t N, HWY_IF_FLOAT(T)>
HWY_API Mask128<T, N> IsInf(const Vec128<T, N> v) {
const DFromV<decltype(v)> d;
const RebindToUnsigned<decltype(d)> du;
const VFromD<decltype(du)> vi = BitCast(du, v);
// 'Shift left' to clear the sign bit, check for exponent=max and mantissa=0.
return RebindMask(d, Eq(Add(vi, vi), Set(du, hwy::MaxExponentTimes2<T>())));
}
```
I noticed the bug happens in other places in highway for other targets too
(including x86_64).
this code is undefined due to an signed integer overflow and that is why using
unsigned is needed.
Yes -fsanitize=undefined does not currently work for vectors (that is a known
limitation).
