On Tue, Jun 6, 2023 at 10:36 PM Uros Bizjak <ubiz...@gmail.com> wrote:
>
> On Tue, Jun 6, 2023 at 1:42 PM Hongtao Liu <crazy...@gmail.com> wrote:
> >
> > On Tue, Jun 6, 2023 at 5:11 PM Uros Bizjak <ubiz...@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.
>
> Uros.-- BR, Hongtao
