RE: [PATCH v2] x86: make better use of VBROADCASTSS / VPBROADCASTD

[Liu, Hongtao via Gcc-patches]

> -----Original Message-----
> From: Jan Beulich <jbeul...@suse.com>
> Sent: Wednesday, June 21, 2023 8:40 PM
> To: Hongtao Liu <crazy...@gmail.com>
> Cc: gcc-patches@gcc.gnu.org; Kirill Yukhin <kirill.yuk...@gmail.com>; Liu,
> Hongtao <hongtao....@intel.com>
> Subject: Re: [PATCH v2] x86: make better use of VBROADCASTSS /
> VPBROADCASTD
> 
> On 21.06.2023 09:44, Jan Beulich wrote:
> > On 21.06.2023 09:37, Hongtao Liu wrote:
> >> On Wed, Jun 21, 2023 at 2:06 PM Jan Beulich via Gcc-patches
> >> <gcc-patches@gcc.gnu.org> wrote:
> >>>
> >>> Isn't prefix_extra use bogus here? What extra prefix does
> >>> vbroadcastss
> >> According to comments, yes, no extra prefix is needed.
> >>
> >> ;; There are also additional prefixes in 3DNOW, SSSE3.
> >> ;; ssemuladd,sse4arg default to 0f24/0f25 and DREX byte, ;;
> >> sseiadd1,ssecvt1 to 0f7a with no DREX byte.
> >> ;; 3DNOW has 0f0f prefix, SSSE3 and SSE4_{1,2} 0f38/0f3a.
> >
> > Right, that's what triggered my question. I guess dropping these
> > "prefix_extra" really wants to be a separate patch (or maybe even
> > multiple, but it's hard to see how to split), dealing with all of the
> > instances which likely have accumulated simply via copy-and-paste.
> 
> Or wait - I'm altering those lines anyway, so I could as well drop them right
> away (and slightly shrink patch size), if that's okay with you. Of course I
> should then not forget to also mention this in the changelog entry.
> 
Yes.
> Jan