From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id E596B3858D37; Sat, 22 Jan 2022 17:03:20 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E596B3858D37
From: "kvr000 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/104188] New: gcc omitting AVX-512 broadcast instruction
Date: Sat, 22 Jan 2022 17:03:20 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 11.2.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: kvr000 at gmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-104188-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Sat, 22 Jan 2022 17:03:21 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104188

            Bug ID: 104188
           Summary: gcc omitting AVX-512 broadcast instruction
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kvr000 at gmail dot com
  Target Milestone: ---

Hi,
there is a bug when generating AVX-512 instructions from intrinsics.  The c=
ode
is generated correctly in gcc-10 but gcc-11 completely omits the
vbroadcastf32x4 .

gcc version: 11.2.0-7ubuntu2 - 11.2.0

Source code of minimal working example:
// Matrix 4*4 multiplication:

#ifndef NO_VECTORIZE
#ifdef __x86_64__
#include <immintrin.h>
#include <x86intrin.h>
#endif
#ifdef __aarch64__
#include <arm_neon.h>
#endif
#endif

union Mat44 {
        float m[4][4];
#ifndef NO_VECTORIZE
#ifdef __x86_64__
        __m128 row[4];
        __m256 rowDuet[2];
        __m512 rowQuad;
#endif
#ifdef __aarch64__
        float32x4_t row[4];
#endif
#endif
};

void matmult_avx512(union Mat44 *out, union Mat44 *a, union Mat44 *b)
{
        __m512 a0123 =3D _mm512_loadu_ps(a->m[0]);
        __m512 b0000 =3D _mm512_broadcast_f32x4(b->row[0]);
        __m512 b1111 =3D _mm512_broadcast_f32x4(b->row[1]);
        __m512 b2222 =3D _mm512_broadcast_f32x4(b->row[2]);
        __m512 b3333 =3D _mm512_broadcast_f32x4(b->row[3]);

        __m512 result =3D _mm512_mul_ps(_mm512_permute_ps(a0123, 0x00), b00=
00);
        result =3D _mm512_fmadd_ps(_mm512_permute_ps(a0123, 0x55), b1111,
result);
        result =3D _mm512_fmadd_ps(_mm512_permute_ps(a0123, 0xaa), b2222,
result);
        result =3D _mm512_fmadd_ps(_mm512_permute_ps(a0123, 0xff), b3333,
result);

        _mm512_storeu_ps(out->m[0], result);
}


gcc-10 (correct):

        endbr64
        vmovups (%rsi), %zmm0
        vbroadcastf32x4 (%rdx), %zmm6           // note here
        vpermilps       $0, %zmm0, %zmm1
        vmulps  %zmm6, %zmm1, %zmm1
        vbroadcastf32x4 16(%rdx), %zmm5         // note here
        vpermilps       $85, %zmm0, %zmm2
        vbroadcastf32x4 32(%rdx), %zmm4         // note here
        vbroadcastf32x4 48(%rdx), %zmm3         // note here
        vfmadd132ps     %zmm5, %zmm1, %zmm2
        vpermilps       $170, %zmm0, %zmm1
        vpermilps       $255, %zmm0, %zmm0
        vfmadd132ps     %zmm4, %zmm2, %zmm1
        vfmadd132ps     %zmm3, %zmm1, %zmm0
        vmovups %zmm0, (%rdi)
        vzeroupper
        ret


gcc-11 (missing vbroadcasatf32x4) :

        endbr64
        vmovups (%rsi), %zmm0
        vpermilps       $0, %zmm0, %zmm1
        vmulps  (%rdx){1to16}, %zmm1, %zmm1
        vpermilps       $85, %zmm0, %zmm2
        vfmadd132ps     16(%rdx){1to16}, %zmm1, %zmm2
        vpermilps       $170, %zmm0, %zmm1
        vpermilps       $255, %zmm0, %zmm0
        vfmadd132ps     32(%rdx){1to16}, %zmm2, %zmm1
        vfmadd132ps     48(%rdx){1to16}, %zmm1, %zmm0
        vmovups %zmm0, (%rdi)
        vzeroupper
        ret=