[Bug target/110118] New: Miss CSE optimization for vptest after r14-1466-g3635e8c67e13e3da7e1e23a617dd9952218e93e0

[Bug target/110118] New: Miss CSE optimization for vptest after r14-1466-g3635e8c67e13e3da7e1e23a617dd9952218e93e0

[crazylht at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110118

            Bug ID: 110118
           Summary: Miss CSE optimization for vptest after
                    r14-1466-g3635e8c67e13e3da7e1e23a617dd9952218e93e0
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: crazylht at gmail dot com
  Target Milestone: ---

#include <immintrin.h>

int do_stuff(__m256i Y0, __m256i Y1, __m128i X2) {
  __m256i And01 = _mm256_and_si256(Y0, Y1);
  int TestResult = _mm256_testc_si256(And01, And01);
  int t1 = _mm256_testz_si256(And01, And01);
  return TestResult + t1;
}


GCC 12.2 generates

do_stuff:
        vpand   %ymm1, %ymm0, %ymm0
        xorl    %eax, %eax
        vptest  %ymm0, %ymm0
        sete    %al
        adcl    $0, %eax
        ret

GCC trunk generates

do_stuff:
        vpand   %ymm1, %ymm0, %ymm0
        xorl    %eax, %eax
        vptest  %ymm0, %ymm0
        setc    %al
        xorl    %edx, %edx
        vptest  %ymm0, %ymm0
        sete    %dl
        addl    %edx, %eax
        ret

[Bug target/110118] Miss CSE optimization for vptest after r14-1466-g3635e8c67e13e3da7e1e23a617dd9952218e93e0

[crazylht at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110118

Hongtao.liu <crazylht at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #1 from Hongtao.liu <crazylht at gmail dot com> ---
.

*** This bug has been marked as a duplicate of bug 80040 ***

[Bug target/110118] Miss CSE optimization for vptest after r14-1466-g3635e8c67e13e3da7e1e23a617dd9952218e93e0

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110118

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Roger Sayle <sayle@gcc.gnu.org>:

https://gcc.gnu.org/g:5322f009e8f7d1c7a1c9aab7cb4c90c433398fdd

commit r14-2030-g5322f009e8f7d1c7a1c9aab7cb4c90c433398fdd
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Thu Jun 22 07:43:07 2023 +0100

    i386: Convert ptestz of pandn into ptestc.

    This patch is the next installment in a set of backend patches around
    improvements to ptest/vptest.  A previous patch optimized the sequence
    t=pand(x,y); ptestz(t,t) into the equivalent ptestz(x,y), using the
    property that ZF is set to (X&Y) == 0.  This patch performs a similar
    transformation, converting t=pandn(x,y); ptestz(t,t) into the (almost)
    equivalent ptestc(y,x), using the property that the CF flags is set to
    (~X&Y) == 0.  The tricky bit is that this sets the CF flag instead of
    the ZF flag, so we can only perform this transformation when we can
    also convert the flags consumer, as well as the producer.

    For the test case:

    int foo (__m128i x, __m128i y)
    {
      __m128i a = x & ~y;
      return __builtin_ia32_ptestz128 (a, a);
    }

    With -O2 -msse4.1 we previously generated:

    foo:    pandn   %xmm0, %xmm1
            xorl    %eax, %eax
            ptest   %xmm1, %xmm1
            sete    %al
            ret

    with this patch we now generate:

    foo:    xorl    %eax, %eax
            ptest   %xmm0, %xmm1
            setc    %al
            ret

    At the same time, this patch also provides alternative fixes for
    PR target/109973 and PR target/110118, by recognizing that ptestc(x,x)
    always sets the carry flag (X&~X is always zero).  This is achieved
    both by recognizing the special case in ix86_expand_sse_ptest and with
    a splitter to convert an eligible ptest into an stc.

    2023-06-22  Roger Sayle  <roger@nextmovesoftware.com>
                Uros Bizjak  <ubizjak@gmail.com>

    gcc/ChangeLog
            * config/i386/i386-expand.cc (ix86_expand_sse_ptest): Recognize
            expansion of ptestc with equal operands as producing const1_rtx.
            * config/i386/i386.cc (ix86_rtx_costs): Provide accurate cost
            estimates of UNSPEC_PTEST, where the ptest performs the PAND
            or PAND of its operands.
            * config/i386/sse.md (define_split): Transform CCCmode UNSPEC_PTEST
            of reg_equal_p operands into an x86_stc instruction.
            (define_split): Split pandn/ptestz/set{n?}e into ptestc/set{n?}c.
            (define_split): Similar to above for strict_low_part destinations.
            (define_split): Split pandn/ptestz/j{n?}e into ptestc/j{n?}c.

    gcc/testsuite/ChangeLog
            * gcc.target/i386/avx-vptest-4.c: New test case.
            * gcc.target/i386/avx-vptest-5.c: Likewise.
            * gcc.target/i386/avx-vptest-6.c: Likewise.
            * gcc.target/i386/pr109973-1.c: Update test case.
            * gcc.target/i386/pr109973-2.c: Likewise.
            * gcc.target/i386/sse4_1-ptest-4.c: New test case.
            * gcc.target/i386/sse4_1-ptest-5.c: Likewise.
            * gcc.target/i386/sse4_1-ptest-6.c: Likewise.