Re: [PATCH 02/24] tcg: Use tcg_gen_negsetcond_*

[Peter Maydell]

On Tue, 8 Aug 2023 at 04:13, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  tcg/tcg-op-gvec.c | 6 ++----
>  tcg/tcg-op.c      | 6 ++----
>  2 files changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/tcg/tcg-op-gvec.c b/tcg/tcg-op-gvec.c
> index a062239804..e260a07c61 100644
> --- a/tcg/tcg-op-gvec.c
> +++ b/tcg/tcg-op-gvec.c
> @@ -3692,8 +3692,7 @@ static void expand_cmp_i32(uint32_t dofs, uint32_t 
> aofs, uint32_t bofs,
>      for (i = 0; i < oprsz; i += 4) {
>          tcg_gen_ld_i32(t0, cpu_env, aofs + i);
>          tcg_gen_ld_i32(t1, cpu_env, bofs + i);
> -        tcg_gen_setcond_i32(cond, t0, t0, t1);
> -        tcg_gen_neg_i32(t0, t0);
> +        tcg_gen_negsetcond_i32(cond, t0, t0, t1);
>          tcg_gen_st_i32(t0, cpu_env, dofs + i);
>      }

Is it not possible for the optimizer to notice "you did
a setcond followed by a neg, let me turn it into negsetcond
for you" ?

thanks
-- PMM