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

[Uros Bizjak <ubizjak@gmail.com>]

On Tue, Aug 13, 2019 at 9:54 PM H.J. Lu <hjl.tools@gmail.com> wrote:

> > > with the latest patch (this is with -m32) where -mstv causes
> > > all spills to go away and the cmoves replaced (so clearly
> > > better code after the patch) for pr65105-5.c, no obvious
> > > improvements for pr65105-3.c where cmov does appear with -mstv.
> > > I'd rather not "fix" those by adding -mno-stv but instead have
> > > the Intel people fix costing for slm and/or decide what to do.
> > > For pr65105-3.c I'm not sure why if-conversion didn't choose
> > > to use cmov, so clearly the enabled minmax patterns expose the
> > > "failure" here.
> > I'm not sure how much effort Intel is putting into Silvermont tuning
> > these days.  So I'd suggest giving HJ a heads-up and a reasonable period
> > of time to take a looksie, but I wouldn't hold the patch for long due to
> > a Silvermont tuning issue.
>
> Leave pr65105-3.c to fail for now.  We can take a look later.

I have a patch for this. The problem is with conversion of COMPARE,
which gets assigned to SImode chain, while in fact we expect very
specific form of DImode compare.

Uros.