[Bug target/115069] [14/15 regression] 8 bit integer vector performance regression, x86, between gcc-14 and gcc-13 using avx2 target clones on skylake platform

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115069

--- Comment #5 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Krzysztof Kanas from comment #4)
> I bisected the issue and it seems that commit
> 0368fc54bc11f15bfa0ed9913fd0017815dfaa5d introduces regression.

I guess the real guilty commit is 

commit 52ff3f7b863da1011b73c0ab3b11f6c78b6451c7
Author: Uros Bizjak <ubiz...@gmail.com>
Date:   Thu May 25 19:40:26 2023 +0200

    i386: Use 2x-wider modes when emulating QImode vector instructions

    Rewrite ix86_expand_vecop_qihi2 to expand fo 2x-wider (e.g. V16QI ->
V16HImode)
    instructions when available.  Currently, the compiler generates following
    assembly for V16QImode multiplication (-mavx2):