On Tue, Oct 24, 2023 at 2:26 AM Richard Henderson <
richard.hender...@linaro.org> wrote:
> On 10/23/23 09:09, Philippe Mathieu-Daudé wrote:
> > Inspired-by: Richard Henderson <richard.hender...@linaro.org>
> > Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
> > ---
> > RFC: please double-check bits
> > ---
> > target/cris/translate.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/target/cris/translate.c b/target/cris/translate.c
> > index 65b07e1d80..3a161f8f73 100644
> > --- a/target/cris/translate.c
> > +++ b/target/cris/translate.c
> > @@ -336,8 +336,7 @@ static void t_gen_cris_mstep(TCGv d, TCGv a, TCGv b,
> TCGv ccs)
> > */
> > t = tcg_temp_new();
> > tcg_gen_shli_tl(d, a, 1);
> > - tcg_gen_shli_tl(t, ccs, 31 - 3);
> > - tcg_gen_sari_tl(t, t, 31);
> > + tcg_gen_sextract_tl(t, ccs, 3, 1);
> tcg_gen_sextract_tl(t, ccs, ctz32(N_FLAG), 1);
>
Looks good!
I think the intent was a branch-free version of:
if (ccs & N_FLAG) {
d += b;
}
Or:
t = ccs & N_FLAG ? UINT32_MAX : 0;
d += b & t;
>
> Also, it appears t_gen_cris_mstep consumes CCS without making sure that it
> is up-to-date.
> Edgar?
>
>
Yes, that looks suspicious!
Best regards,
Edgar
>
> r~
>
