Re: [Qemu-devel] [PATCH 13/14] i386: optimize setbe

[Blue Swirl]

On Sat, Oct 6, 2012 at 12:30 PM, Paolo Bonzini <address@hidden> wrote:
> This is looking at EFLAGS, but it can do so more efficiently with
> setcond.
>
> Signed-off-by: Paolo Bonzini <address@hidden>

Reviewed-by: Blue Swirl <address@hidden>

> ---
>  target-i386/translate.c | 7 +++----
>  1 file modificato, 3 inserzioni(+), 4 rimozioni(-)
>
> diff --git a/target-i386/translate.c b/target-i386/translate.c
> index fb44839..342b9ec 100644
> --- a/target-i386/translate.c
> +++ b/target-i386/translate.c
> @@ -1031,10 +1031,9 @@ static inline void gen_setcc_slow(DisasContext *s, int 
> jcc_op, TCGv reg, bool in
>          return;
>      case JCC_BE:
>          gen_compute_eflags(s);
> -        tcg_gen_shri_tl(reg, cpu_cc_src, 6);
> -        tcg_gen_or_tl(reg, reg, cpu_cc_src);
> -        tcg_gen_andi_tl(reg, reg, 1);
> -        break;
> +        tcg_gen_andi_tl(reg, cpu_cc_src, 0x41);

Symbolic names for the flags would be nice.

> +        tcg_gen_setcondi_tl(inv ? TCG_COND_EQ : TCG_COND_NE, reg, reg, 0);
> +        return;
>      case JCC_S:
>          gen_compute_eflags_s(s, reg, inv);
>          return;
> --
> 1.7.12.1
>
>
>