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From: "hubicka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/111064] 5-10% regression of parest on icelake between
 g:d073e2d75d9ed492de9a8dc6970e5b69fae20e5a (Aug 15 2023) and
 g:9ade70bb86c8744f4416a48bb69cf4705f00905a (Aug 16)
Date: Fri, 18 Aug 2023 12:39:53 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111064

--- Comment #1 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Maybe
commit 3064d1f5c48cb6ce1b4133570dd08ecca8abb52d
Author: liuhongt <hongtao.liu@intel.com>
Date:   Thu Aug 10 11:41:39 2023 +0800

    Software mitigation: Disable gather generation in vectorization for GDS
affected Intel Processors.

    For more details of GDS (Gather Data Sampling), refer to
=20=20=20
https://www.intel.com/content/www/us/en/developer/articles/technical/softwa=
re-security-guidance/advisory-guidance/gather-data-sampling.html

    After microcode update, there's performance regression. To avoid that,
    the patch disables gather generation in autovectorization but uses
    gather scalar emulation instead.=