[Mesa-dev] [PATCH 10/12] i965/fs: Make compact_virtual_grfs an optimization pass

[Matt Turner]

On Fri, Sep 19, 2014 at 1:10 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> Previously we disabled compact_virtual_grfs when dumping optimizations.
> The idea here was to make it easier to diff the dumped shader because you
> didn't have a sudden renaming.  However, sometimes a bug is affected by
> compact_virtual_grfs and, when this happens, you want to keep dumping
> instructions with compact_virtual_grfs enabled.  By turning it into an
> optimization pass and dumping it along with the others, we retain the
> ability to diff because you can just diff against the compact_virtual_grf
> output.

I'd like to understand the bug you encountered.

I'm kind of concerned that we're going to just run the optimization
loop an extra time for every shader now, since compact_virtual_grfs is
going to set progress = true after the last actual optimization pass
made progress. I guess we could remove that problem by calling
compact_virtual_grfs at the end of the loop, rather than at the
beginning.