Re: [PATCH][RFC] Add x86 subadd SLP pattern

[Richard Biener <rguenther@suse.de>]

On Thu, 17 Jun 2021, Uros Bizjak wrote:

> On Thu, Jun 17, 2021 at 11:44 AM Richard Biener <rguenther@suse.de> wrote:
> >
> > This addds SLP pattern recognition for the SSE3/AVX [v]addsubp{ds} v0, v1
> > instructions which compute { v0[0] - v1[0], v0[1], + v1[1], ... }
> > thus subtract, add alternating on lanes, starting with subtract.
> >
> > It adds a corresponding optab and direct internal function,
> > vec_subadd$a3 and at the moment to make the i386 backend changes
> > "obvious", duplicates the existing avx_addsubv4df3 pattern with
> > the new canonical name (CODE_FOR_* and gen_* are used throughout the
> > intrinsic code, so the actual change to rename all existing patterns
> > will be quite a bit bigger).  I expect some bike-shedding on
> > subadd vs. addsub so I delay that change ;)
> 
> Well, the pattern is called addsub in the x86 world because highpart
> does add and lowpart does sub. In left-to-right writing systems
> highpart comes before lowpart, so you have addsub.

The other targets mentioned do not seem to agree but I can live
with that, thus I'll change back to addsub.

Richard.