Re: [PATCH] Fold _mm{, 256, 512}_abs_{epi8, epi16, epi32, epi64} into gimple ABSU_EXPR + VCE.

[Hongtao Liu <crazylht@gmail.com>]

On Wed, Jun 7, 2023 at 8:31 AM Hongtao Liu <crazylht@gmail.com> wrote:
>
> On Tue, Jun 6, 2023 at 10:36 PM Uros Bizjak <ubizjak@gmail.com> wrote:
> >
> > On Tue, Jun 6, 2023 at 1:42 PM Hongtao Liu <crazylht@gmail.com> wrote:
> > >
> > > On Tue, Jun 6, 2023 at 5:11 PM Uros Bizjak <ubizjak@gmail.com> wrote:
> > > >
> > > > On Tue, Jun 6, 2023 at 6:33 AM liuhongt via Gcc-patches
> > > > <gcc-patches@gcc.gnu.org> wrote:
> > > > >
> > > > > r14-1145 fold the intrinsics into gimple ABS_EXPR which has UB for
> > > > > TYPE_MIN, but PABSB will store unsigned result into dst. The patch
> > > > > uses ABSU_EXPR + VCE instead of ABS_EXPR.
> > > > >
> > > > > Also don't fold _mm_abs_{pi8,pi16,pi32} w/o TARGET_64BIT since 64-bit
> > > > > vector absm2 is guarded with TARGET_MMX_WITH_SSE.
> > > >
> > > >This should be !TARGET_MMX_WITH_SSE. TARGET_64BIT is not enough, see
> > > >the definition of T_M_W_S in i386.h. OTOH, these builtins are
> > > >available for TARGET_MMX, so I'm not sure if the above check is needed
> > > >at all.
> > > BDESC (OPTION_MASK_ISA_SSSE3 | OPTION_MASK_ISA_MMX, 0,
> > > CODE_FOR_ssse3_absv8qi2, "__builtin_ia32_pabsb", IX86_BUILTIN_PABSB,
> > > UNKNOWN, (int) V8QI_FTYPE_V8QI)
> > >
> > > ISA requirement(OPTION_MASK_ISA_SSSE3 | OPTION_MASK_ISA_MMX) will be
> > > checked by ix86_check_builtin_isa_match which is at the beginning of
> > > ix86_gimple_fold_builtin.
> > > Here, we're folding those builtin into gimple ABSU_EXPR, and
> > > ABSU_EXPR<vector> will be lowered by vec_lower pass when backend
> > > doesn't support corressponding absm2_optab, that's why i only check
> > > TARGET_64BIT here.
> > >
> > > > Please note that we are using builtins here, so we should not fold to
> > > > absm2, but to ssse3_absm2, which is also available with TARGET_MMX.
> > > Yes, that exactly why I checked TARGET_64BIT here, w/ TARGET_64BIT,
> > > backend suppport absm2_optab which exactly matches ssse3_absm2.
> > > w/o TARGET_64BIT, the builtin shouldn't folding into gimple ABSU_EXPR,
> > > but let backend expanded to ssse3_absm2.
> >
> > Thanks for the explanation, but for consistency, I'd recommend
> > checking TARGET_MMX_WITH_SSE (= TARGET_64BIT && TARGET_SSE2) here. The
> > macro is self-explanatory, while the usage of TARGET_64BIT is not that
> > descriptive.
> Sure.
Pushed to trunk.
> >
> > Uros.
>
>
>
> --
> BR,
> Hongtao



-- 
BR,
Hongtao