[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

[haochen.jiang at intel dot com via Gcc-bugs]

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

--- Comment #6 from Haochen Jiang <haochen.jiang at intel dot com> ---
(In reply to Hongtao Liu from comment #5)
> (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):

Yes, since 0368fc54bc11f15bfa0ed9913fd0017815dfaa5d only fixed a typo in that
patch.

Original thread: https://gcc.gnu.org/pipermail/gcc-patches/2023-May/619745.html