[Mesa-dev] [PATCH 1/2] [RFC] i965/vec4: Reward spills in if/else/endif blocks

Matt Turner mattst88 at gmail.com
Fri Jun 19 20:04:51 PDT 2015

On Fri, Jun 19, 2015 at 6:53 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:
> I don't think this is doing what you think it's doing. This code is
> for calculating the *cost* of spills, so a higher cost means a lower
> priority for choosing the register. We increase the cost for things
> inside loops because we don't want to spill inside loops, and by doing
> the same thing for if's you're actually discouraging spills inside an
> if block.

Top quoting is bad, m'kay.

But, I think it is doing what he thinks since he increases costs for
ENDIF and decreases costs for IF. That is, it's backwards from

Why this is a good thing to do... I don't know. I'd expect some data
along with this patch in order to evaluate it properly.

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