On Tue, Dec 14, 2021 at 10:55:01AM +0100, Martin Liška wrote:
> The patch fixes __builtin_cpu_supports("avx512vbmi2") which returns a negative
> value (that's not allowed in the documentation).
>
> I also checked ppc target that does the same, and __builtin_cpu_is, which
> are fine.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
> Ready to be installed?
> Thanks,
> Martin
>
> PR target/103661
>
> gcc/ChangeLog:
>
> * config/i386/i386-builtins.c (fold_builtin_cpu): Compare to 0
> as API expects that non-zero values are returned. For
> "avx512vbmi2" argument, we return now 1 << 31, which is a
> negative integer value.
> ---
> gcc/config/i386/i386-builtins.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/config/i386/i386-builtins.c b/gcc/config/i386/i386-builtins.c
> index 0fb14b55712..7e57b665c1e 100644
> --- a/gcc/config/i386/i386-builtins.c
> +++ b/gcc/config/i386/i386-builtins.c
> @@ -2353,7 +2353,8 @@ fold_builtin_cpu (tree fndecl, tree *args)
> /* Return __cpu_model.__cpu_features[0] & field_val */
> final = build2 (BIT_AND_EXPR, unsigned_type_node, array_elt,
> build_int_cstu (unsigned_type_node, field_val));
> - return build1 (CONVERT_EXPR, integer_type_node, final);
> + return build2 (NE_EXPR, integer_type_node, final,
> + build_int_cst (unsigned_type_node, 0));
> }
> gcc_unreachable ();
> }
Wouldn't this be better done only if field_val has the msb set
and keep the CONVERT_EXPR otherwise (why isn't it NOP_EXPR?)?
Jakub
