Re: [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions

[Richard Henderson]

On 1/7/25 02:29, Philippe Mathieu-Daudé wrote:
> Hi Richard,
>
> On 2/1/25 19:16, Richard Henderson wrote:
> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> > ---
> >   tcg/riscv/tcg-target-has.h |  8 +++++++-
> >   tcg/riscv/tcg-target.c.inc | 13 +++++++++++--
> >   2 files changed, 18 insertions(+), 3 deletions(-)
> >
> > diff --git a/tcg/riscv/tcg-target-has.h b/tcg/riscv/tcg-target-has.h
> > index 10e61edc45..ea38ee5cbb 100644
> > --- a/tcg/riscv/tcg-target-has.h
> > +++ b/tcg/riscv/tcg-target-has.h
> > @@ -64,7 +64,13 @@ tcg_target_extract_valid(TCGType type, unsigned ofs, 
> > unsigned len)
> >           /* ofs > 0 uses SRLIW; ofs == 0 uses add.uw. */
> >           return ofs || (cpuinfo & CPUINFO_ZBA);
> >       }
> > -    return (cpuinfo & CPUINFO_ZBB) && ofs == 0 && len == 16;
> > +    switch (len) {
> > +    case 1:
> > +        return (cpuinfo & CPUINFO_ZBS) && ofs != 0;
>
> Why can't we have ofs=0?

To prefer ANDI.


r~