RE: [PATCH] [i386]Add combine splitter to transform pxor/pcmpeqb/pmovmskb/cmp 0xffff to ptest.

["Jiang, Haochen" <haochen.jiang@intel.com>]

> -----Original Message-----
> From: Hongyu Wang <wwwhhhyyy333@gmail.com>
> Sent: Friday, May 6, 2022 4:50 PM
> To: Jiang, Haochen <haochen.jiang@intel.com>
> Cc: GCC Patches <gcc-patches@gcc.gnu.org>; Liu, Hongtao
> <hongtao.liu@intel.com>
> Subject: Re: [PATCH] [i386]Add combine splitter to transform
> pxor/pcmpeqb/pmovmskb/cmp 0xffff to ptest.
> 
> > +(define_split
> > +  [(set (reg:CCZ FLAGS_REG)
> > +       (compare:CCZ (unspec:SI
> > +                       [(eq:VI1_AVX2
> > +                           (match_operand:VI1_AVX2 0 "vector_operand")
> > +                           (match_operand:VI1_AVX2 1 "const0_operand"))]
> > +                   UNSPEC_MOVMSK)
> > +                (match_operand 2 "const_int_operand")))]
> > +  "TARGET_SSE4_1 && ix86_match_ccmode (insn, CCmode)
> 
> It looks like set_src and set_dst are all CCZmode, do we really need
> ix86_match_ccmode?
> 
> > +  && (INTVAL (operands[2]) == (int) (<vi1avx2const>))"
> 
> I think (int) convert is not needed for const, and INTVAL actually
> returns HOST_WIDE_INT

It should be int convert here, because we need 0xfffffff become -1 in this compare.

Haochen.

> 
> > +#include <stdbool.h>
> > +
> > +bool is_zero(__m128i x)
> 
> bool is not necessary here, we can use int and drop stdbool.
> 
> Haochen Jiang via Gcc-patches <gcc-patches@gcc.gnu.org> 于2022年5月6
> 日周五 16:01写道：
> >
> > Hi all,
> >
> > This patch aims to add a combine splitter to transform
> pxor/pcmpeqb/pmovmskb/cmp 0xffff to ptest.
> >
> > Regtested on x86_64-pc-linux-gnu. Ok for trunk?
> >
> > BRs,
> > Haochen
> >
> > gcc/ChangeLog:
> >
> >         PR target/104371
> >         * config/i386/sse.md: Add new define_mode_attr and define_split.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         PR target/104371
> >         * gcc.target/i386/pr104371-1.c: New test.
> >         * gcc.target/i386/pr104371-2.c: Ditto.
> > ---
> >  gcc/config/i386/sse.md                     | 19 +++++++++++++++++++
> >  gcc/testsuite/gcc.target/i386/pr104371-1.c | 14 ++++++++++++++
> >  gcc/testsuite/gcc.target/i386/pr104371-2.c | 14 ++++++++++++++
> >  3 files changed, 47 insertions(+)
> >  create mode 100644 gcc/testsuite/gcc.target/i386/pr104371-1.c
> >  create mode 100755 gcc/testsuite/gcc.target/i386/pr104371-2.c
> >
> > diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
> > index 7b791def542..71afda73c8f 100644
> > --- a/gcc/config/i386/sse.md
> > +++ b/gcc/config/i386/sse.md
> > @@ -20083,6 +20083,25 @@
> >     (set_attr "prefix" "maybe_vex")
> >     (set_attr "mode" "SI")])
> >
> > +;; Optimize pxor/pcmpeqb/pmovmskb/cmp 0xffff to ptest.
> > +(define_mode_attr vi1avx2const
> > +  [(V32QI "0xffffffff") (V16QI "0xffff")])
> > +
> > +(define_split
> > +  [(set (reg:CCZ FLAGS_REG)
> > +       (compare:CCZ (unspec:SI
> > +                       [(eq:VI1_AVX2
> > +                           (match_operand:VI1_AVX2 0 "vector_operand")
> > +                           (match_operand:VI1_AVX2 1 "const0_operand"))]
> > +                   UNSPEC_MOVMSK)
> > +                (match_operand 2 "const_int_operand")))]
> > +  "TARGET_SSE4_1 && ix86_match_ccmode (insn, CCmode)
> > +  && (INTVAL (operands[2]) == (int) (<vi1avx2const>))"
> > +  [(set (reg:CC FLAGS_REG)
> > +       (unspec:CC [(match_dup 0)
> > +                   (match_dup 0)]
> > +                  UNSPEC_PTEST))])
> > +
> >  (define_expand "sse2_maskmovdqu"
> >    [(set (match_operand:V16QI 0 "memory_operand")
> >         (unspec:V16QI [(match_operand:V16QI 1 "register_operand")
> > diff --git a/gcc/testsuite/gcc.target/i386/pr104371-1.c
> b/gcc/testsuite/gcc.target/i386/pr104371-1.c
> > new file mode 100644
> > index 00000000000..df7c0b074e3
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/i386/pr104371-1.c
> > @@ -0,0 +1,14 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O2 -msse4" } */
> > +/* { dg-final { scan-assembler "ptest\[ \\t\]" } } */
> > +/* { dg-final { scan-assembler-not "pxor\[ \\t\]" } } */
> > +/* { dg-final { scan-assembler-not "pcmpeqb\[ \\t\]" } } */
> > +/* { dg-final { scan-assembler-not "pmovmskb\[ \\t\]" } } */
> > +
> > +#include <smmintrin.h>
> > +#include <stdbool.h>
> > +
> > +bool is_zero(__m128i x)
> > +{
> > +  return _mm_movemask_epi8(_mm_cmpeq_epi8(x, _mm_setzero_si128()))
> == 0xffff;
> > +}
> > diff --git a/gcc/testsuite/gcc.target/i386/pr104371-2.c
> b/gcc/testsuite/gcc.target/i386/pr104371-2.c
> > new file mode 100755
> > index 00000000000..f0d0afd5897
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/i386/pr104371-2.c
> > @@ -0,0 +1,14 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O2 -mavx2" } */
> > +/* { dg-final { scan-assembler "vptest\[ \\t\]" } } */
> > +/* { dg-final { scan-assembler-not "vpxor\[ \\t\]" } } */
> > +/* { dg-final { scan-assembler-not "vpcmpeqb\[ \\t\]" } } */
> > +/* { dg-final { scan-assembler-not "vpmovmskb\[ \\t\]" } } */
> > +
> > +#include <immintrin.h>
> > +#include <stdbool.h>
> > +
> > +bool is_zero256(__m256i x)
> > +{
> > +  return _mm256_movemask_epi8(_mm256_cmpeq_epi8(x,
> _mm256_setzero_si256())) == 0xffffffff;
> > +}
> > --
> > 2.18.1
> >