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Re: [patch, fortran] Enable FMA for AVX2 and AVX512F for matmul
- From: Thomas Koenig <tkoenig at netcologne dot de>
- To: Janne Blomqvist <blomqvist dot janne at gmail dot com>
- Cc: "fortran at gcc dot gnu dot org" <fortran at gcc dot gnu dot org>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 2 Mar 2017 08:50:45 +0100
- Subject: Re: [patch, fortran] Enable FMA for AVX2 and AVX512F for matmul
- Authentication-results: sourceware.org; auth=none
- References: <6ecdb93d-3aef-746c-8ca0-ed6b78eb12d4@netcologne.de> <CAO9iq9EvG1_So5NRZ78z7pEdoR=4oZu9t+yabi5Lj-qpP46-Eg@mail.gmail.com>
Am 02.03.2017 um 08:32 schrieb Janne Blomqvist:
On Wed, Mar 1, 2017 at 11:00 PM, Thomas Koenig <tkoenig@netcologne.de> wrote:
Hello world,
the attached patch enables FMA for the AVX2 and AVX512F variants of
matmul. This should bring a very nice speedup (although I have
been unable to run benchmarks due to lack of a suitable machine).
In lieu of benchmarks, have you looked at the generated asm to verify
that fma is actually used?
Yes, I did.
Here's something from the new matmul_r8_avx2:
156c: c4 62 e5 b8 fd vfmadd231pd %ymm5,%ymm3,%ymm15
1571: c4 c1 79 10 04 06 vmovupd (%r14,%rax,1),%xmm0
1577: c4 62 dd b8 db vfmadd231pd %ymm3,%ymm4,%ymm11
157c: c4 c3 7d 18 44 06 10 vinsertf128
$0x1,0x10(%r14,%rax,1),%ymm0,%ymm0
1583: 01
1584: c4 62 ed b8 ed vfmadd231pd %ymm5,%ymm2,%ymm13
1589: c4 e2 ed b8 fc vfmadd231pd %ymm4,%ymm2,%ymm7
158e: c4 e2 fd a8 ad 30 ff vfmadd213pd
-0x800d0(%rbp),%ymm0,%ymm5
... and here from matmul_r8_avx512f:
1da8: c4 a1 7b 10 14 d6 vmovsd (%rsi,%r10,8),%xmm2
1dae: c4 c2 b1 b9 f0 vfmadd231sd %xmm8,%xmm9,%xmm6
1db3: 62 62 ed 08 b9 e5 vfmadd231sd %xmm5,%xmm2,%xmm28
1db9: 62 62 ed 08 b9 ec vfmadd231sd %xmm4,%xmm2,%xmm29
1dbf: 62 62 ed 08 b9 f3 vfmadd231sd %xmm3,%xmm2,%xmm30
1dc5: c4 e2 91 99 e8 vfmadd132sd %xmm0,%xmm13,%xmm5
1dca: c4 e2 99 99 e0 vfmadd132sd %xmm0,%xmm12,%xmm4
1dcf: c4 e2 a1 99 d8 vfmadd132sd %xmm0,%xmm11,%xmm3
1dd4: c4 c2 a9 99 d1 vfmadd132sd %xmm9,%xmm10,%xmm2
1dd9: c4 c2 89 99 c1 vfmadd132sd %xmm9,%xmm14,%xmm0
1dde: 0f 8e d3 fe ff ff jle 1cb7
<matmul_r8_avx512f+0x1cb7>
... so this is looking pretty good.
Regards
Thomas