Re: [PATCH] i386: Change RTL representation of bt[lq] [PR118623]

[Uros Bizjak]

On Mon, Feb 10, 2025 at 10:09 AM Eric Botcazou <botca...@adacore.com> wrote:
>
> > So, would it be better to represent *bt<mode> as
> > (set (reg:CCC FLAGS_REG)
> >      (compare:CCC (not:SWI48 (zero_extract:SWI48 ...)) (const_int -1)))
> > rather than
> > (set (reg:CCC FLAGS_REG)
> >      (compare:CCC (const_int 0) (zero_extract:SWI48 ...)))
> > ?
>
> FWIW the SPARC port uses the former variant with the CCC & CCXC modes.

Maybe you could use TARGET_CANONICALIZE_COMPARISON for sparc, so you
can use the later variant? I don't think combine simplifies RTXes to
the former variant.

Uros.