[Bug target/81317] builtin_vec_ld fails for powerpc with altivec

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81317

Bill Schmidt <wschmidt at gcc dot gnu.org> changed:

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                 CC|                            |wschmidt at gcc dot gnu.org

--- Comment #12 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
(In reply to Segher Boessenkool from comment #11)
> 
>   __builtin_altivec_vsubuhm (cbh, pw_cj);
> 
> 
> is transformed to
> 
> 
>  = cbh - pw_cj;
> 
> 
> and that blows up.

Yeah, well...the original source is obviously wrong, since
__builtin_altivec_vsubuhm produces a result that is thrown away.

We should avoid optimizing in this situation, but it's an ice-on-invalid.