Re: [PATCH][RFC][x86] Fix PR91154, add SImode smax, allow SImode add in SSE regs

[Richard Biener <rguenther at suse dot de>]

On Fri, 9 Aug 2019, Jakub Jelinek wrote:

> On Fri, Aug 09, 2019 at 11:25:30AM +0200, Richard Biener wrote:
> >   0.65 │1e0:   vpxor  %xmm0,%xmm0,%xmm0
> >   0.32 │       vpmaxs -0x10(%rsp),%xmm0,%xmm0
> >  40.45 │       vmovd  %xmm0,%eax
> >   2.45 │       imul   %r8d,%eax
> 
> Shouldn't we hoist the vpxor before the loop?  Is it STV being done too late
> that we don't do that anymore?  Couldn't e.g. STV itself detect that and put
> the clearing instruction before the loop instead of right before the minmax?

This testcase doesn't have a loop, since the minmax patterns do not
allow constants we need to deal with this for the GPR case as well.
And we do when you look at the loop testcase.

Richard.