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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/101929] [12 Regression] r12-7319 regress x264_r by 4% on
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Date: Fri, 20 May 2022 04:05:01 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101929

--- Comment #12 from Hongtao.liu <crazylht at gmail dot com> ---

> It's difficult (if not impossible) for the vectorizer to second-guess
> the followup FRE, we're a long way from doing loop + SLP vectorization
> in one go and discover we can elide the vector store.

I'm thinking of adding some detect in the vectorizer to find the "fre pair"=
 of
the new vectorized store and existed vector load, then eliminate vector_sto=
re
cost in add_stmt_cost since it's probably be eliminated.

New vector store:  MEM <vector(4) unsigned int> [(unsigned int *)&tmp] =3D
vect__192.68_825;

Existed vector load below: vect__63.9_482 =3D MEM <vector(4) unsigned int>
[(unsigned int *)&tmp]=