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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 07:39:23 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102473

--- Comment #2 from Hongtao.liu <crazylht at gmail dot com> ---
(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 s=
ee
> a domain crossing penalty here(?).  But since this is a generic arch/tuni=
ng
> 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 pattern.
>=20
Guess you're use O3, -ffast-math is needed for v4sf reduction
https://godbolt.org/z/sjf4Pncna

And original code also have movhlps.

BTW: i can't reproduce the regression on CLX/coffelake for one copy run.
options are below

 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)
            "-fno-stack-arrays" (in EXTRA_OPTIMIZE)
            "-Wl,-z,muldefs" (in EXTRA_LDFLAGS)


> /home/rguenther/src/gcc2/gcc/testsuite/gcc.target/i386/sse2-pr101059.c:20=
:21:
> note:   vect_is_simple_use: vectype vector(4) float
> /home/rguenther/src/gcc2/gcc/testsuite/gcc.target/i386/sse2-pr101059.c:20=
:21:
> missed:   reduc op not supported by target.=