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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/102473] [12 Regression] 521.wrf_r 5% slower at -Ofast
 and generic x86_64 tuning after r12-3426-g8f323c712ea76c
Date: Fri, 24 Sep 2021 10:43:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102473

--- Comment #4 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Hongtao.liu from comment #2)
> (In reply to Richard Biener from comment #1)
> > Looks like at least on Zen movs[hl]dup is on the integer domain so we'l=
 see
> > a domain crossing penalty here(?).  But since this is a generic arch/tu=
ning
> > regression the SSE2 code path should be what matters - on the committed
> > testcase I see
> >=20
> > foo:
> > .LFB572:
> >         .cfi_startproc
> >         pxor    %xmm0, %xmm0
> >         addss   (%rdi), %xmm0
> >         addss   4(%rdi), %xmm0
> >         addss   8(%rdi), %xmm0
> >         addss   12(%rdi), %xmm0
> >         ret
> >=20
> > where it seems that the vectorizer doesn't pick up the reduction patter=
n.
> >=20
> Guess you're use O3, -ffast-math is needed for v4sf reduction
> https://godbolt.org/z/sjf4Pncna
>=20
> And original code also have movhlps.
>=20
> BTW: i can't reproduce the regression on CLX/coffelake for one copy run.
> options are below
>=20
>  521.wrf_r: "gfortran -m64" (in FC) "gcc -m64" (in CC)
>             "gfortran -m64" (in LD)
>             "-fconvert=3Dbig-endian -std=3Dlegacy -fno-inline-arg-packing=
" (in
> FPORTABILITY)
>             "-mtune=3Dgeneric -Ofast -mfpmath=3Dsse -fno-associative-math=
" (in
> OPTIMIZE)
Reproduced after removing -fno-associative-math.=