[patch, fortran] Enable FMA for AVX2 and AVX512F for matmul

Thomas Koenig tkoenig@netcologne.de
Thu Mar 2 07:50:00 GMT 2017


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



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