[Mesa-dev] [Mesa-stable] [PATCH] nv50/ir: skip optimizing ADD+SHL to SHLADD when src(1) is 0

[Juan A. Suarez Romero]

On Mon, 2017-05-01 at 12:11 -0400, Ilia Mirkin wrote:
> On Mon, May 1, 2017 at 12:09 PM, Samuel Pitoiset
> <samuel.pitoiset at gmail.com> wrote:
> > On 05/01/2017 05:59 PM, Ilia Mirkin wrote:
> > > 
> > > I think this is off. It shouldn't matter what the code sequence is,
> > > it's all representable. You need to teach replaceZero to not mess
> > > things up for SHLADD's src(1).
> > 
> > 
> > It's representable but stupid to do it. We should keep the ADD there and
> > this also avoids a workaround in the replaceZero logic just for that.
> > 
> > IMHO, this is the better solution.
> 
> Yes, that would be a better optimization. However at this stage, you
> have a y = SHL(x, 0) + ADD(y, z). I think it makes sense to combine
> them into one and let DCE take care of it.
> 
> Ideally we wouldn't get into such a situation, but the real issue is
> that a perfectly representable (if dumb) instruction like SHLADD(x, 0,
> y) gets messed up by replaceZero. We should fix replaceZero. We should
> also try to avoid generating such stupid instructions.
> 

So what was the final conclusion for this patch? Was replaceZero fixed?

	J.A.