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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/104610] memcmp () == 0 can be optimized better for avx512f
Date: Thu, 24 Feb 2022 05:33:38 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104610

--- Comment #10 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to H.J. Lu from comment #9)
> ix86_gen_scratch_sse_rtx was added to prevent combine from changing
> store of vector registers with constant value to store of constant
> value.  You can change ix86_gen_scratch_sse_rtx to return a pseudo
> register and watch the regressions in GCC testsuite.  If we can fix
> these regressions, ix86_gen_scratch_sse_rtx isn't needed.

it regresses, i'm thinking of add a peephole2 to split mov mem to mov + mov=
d +
shufd which can prevent regression for pr100865, and for vzeroupper, i don't
have a good way to avoid those regressions.

gcc.target/i386/pr100865-11b.c scan-assembler-times vmovdqa64[\\t ]%xmm[0-9=
]+,=20
16
gcc.target/i386/pr100865-12b.c scan-assembler-times vmovdqa64[\\t ]%xmm[0-9=
]+,=20
16
gcc.target/i386/pr100865-8a.c scan-assembler-times (?:vpbroadcastd|vpshufd)=
[\\t
]+[^\n]*, %xmm[0-9]+ 1
gcc.target/i386/pr100865-8b.c scan-assembler-times vmovdqa64[\\t ]%xmm[0-9]=
+,=20
16
gcc.target/i386/pr100865-8c.c scan-assembler-times vpshufd[\\t ]+[^\n]*,
%xmm[0-9]+ 1
gcc.target/i386/pr100865-9b.c scan-assembler-times vmovdqa64[\\t ]%xmm[0-9]=
+,=20
16
gcc.target/i386/pr100865-9c.c scan-assembler-times vpshufd[\\t ]+[^\n]*,
%xmm[0-9]+ 1
gcc.target/i386/pr82941-1.c scan-assembler-not vzeroupper
gcc.target/i386/pr82942-1.c scan-assembler-not vzeroupper
gcc.target/i386/pr82990-1.c scan-assembler-not vzeroupper
gcc.target/i386/pr82990-3.c scan-assembler-not vzeroupper
gcc.target/i386/pr82990-5.c scan-assembler-not vzeroupper=