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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/103850] missed optimization in AVX code
Date: Tue, 04 Jan 2022 13:55:47 +0000 [thread overview]
Message-ID: <bug-103850-4-DXuHH3gA2l@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103850-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103850
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note the issue can be reproduced without -ffast-math as well where the
functions are nearly identical so I fear you are running into some
micro-architectural hazard. Maybe
.L3:
vmovapd %ymm2, %ymm0
vmovapd %ymm3, %ymm1
.L2:
vbroadcastsd (%rsi), %ymm2
vbroadcastsd 8(%rsi), %ymm4
addq $32, %rdx
addq $16, %rsi
vmovapd %ymm2, %ymm3
vfmadd132pd -32(%rsp), %ymm4, %ymm2
vfmadd132pd %ymm15, %ymm4, %ymm3
vbroadcastsd -24(%rdx), %ymm4
vfmadd132pd %ymm1, %ymm14, %ymm3
vmovapd %ymm1, %ymm14
vfmadd231pd %ymm1, %ymm4, %ymm11
vfmadd231pd %ymm0, %ymm4, %ymm7
vbroadcastsd -8(%rdx), %ymm4
vfmadd132pd %ymm0, %ymm13, %ymm2
vbroadcastsd -32(%rdx), %ymm13
vfmadd231pd %ymm1, %ymm4, %ymm9
vfmadd231pd %ymm0, %ymm4, %ymm5
vfmadd231pd %ymm1, %ymm13, %ymm12
vfmadd231pd %ymm0, %ymm13, %ymm8
vbroadcastsd -16(%rdx), %ymm13
vfmadd231pd %ymm1, %ymm13, %ymm10
vfmadd231pd %ymm0, %ymm13, %ymm6
vmovapd %ymm0, %ymm13
cmpq %rdx, %rax
jne .L3
is easier to handle since there's only one data dependence on the
addq $32, %rdx of the followup loads but for (slow)
.L8:
vmovapd %ymm2, %ymm0
vmovapd %ymm3, %ymm1
.L7:
vbroadcastsd 8(%rdx), %ymm2
vbroadcastsd (%rdx), %ymm3
addq $16, %rsi
addq $32, %rdx
vbroadcastsd -8(%rsi), %ymm4
vfmadd231pd %ymm1, %ymm2, %ymm11
vfmadd231pd %ymm0, %ymm2, %ymm7
vbroadcastsd -8(%rdx), %ymm2
vfmadd231pd %ymm1, %ymm3, %ymm12
vfmadd231pd %ymm0, %ymm3, %ymm8
vbroadcastsd -16(%rdx), %ymm3
vfmadd231pd %ymm1, %ymm2, %ymm9
vfmadd231pd %ymm0, %ymm2, %ymm5
vbroadcastsd -16(%rsi), %ymm2
vfmadd231pd %ymm1, %ymm3, %ymm10
vfmadd231pd %ymm0, %ymm3, %ymm6
vmovapd %ymm2, %ymm3
vfmadd132pd -32(%rsp), %ymm4, %ymm2
vfmadd132pd %ymm15, %ymm4, %ymm3
vfmadd132pd %ymm1, %ymm14, %ymm3
vmovapd %ymm1, %ymm14
vfmadd132pd %ymm0, %ymm13, %ymm2
vmovapd %ymm0, %ymm13
cmpq %rsi, %rax
jne .L8
both increments impose dependences on the following loads.
next prev parent reply other threads:[~2022-01-04 13:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-28 10:10 [Bug c/103850] New: " martin@mpa-garching.mpg.de
2021-12-28 10:24 ` [Bug target/103850] " pinskia at gcc dot gnu.org
2021-12-28 10:32 ` martin@mpa-garching.mpg.de
2021-12-28 10:41 ` martin@mpa-garching.mpg.de
2022-01-04 13:45 ` rguenth at gcc dot gnu.org
2022-01-04 13:55 ` rguenth at gcc dot gnu.org [this message]
2022-01-04 14:12 ` martin@mpa-garching.mpg.de
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