[Bug target/111064] 5-10% regression of parest on icelake between g:d073e2d75d9ed492de9a8dc6970e5b69fae20e5a (Aug 15 2023) and g:9ade70bb86c8744f4416a48bb69cf4705f00905a (Aug 16)

[hubicka at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111064

--- Comment #1 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Maybe
commit 3064d1f5c48cb6ce1b4133570dd08ecca8abb52d
Author: liuhongt <hongtao....@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
   
https://www.intel.com/content/www/us/en/developer/articles/technical/software-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.