[PATCH 2/3] glamor: Don't optimize out scissor updates in CopyArea.

Eric Anholt eric at anholt.net
Thu Feb 5 10:23:08 PST 2015

Keith Packard <keithp at keithp.com> writes:

> Eric Anholt <eric at anholt.net> writes:
>> This possibly is a minor hit for immediate mode renderers (no
>> difference on copypixin100 on my hsw, n=12), but it gives important
>> information about drawing bounds to a deferred renderer (3.1x
>> improvement in copypixwin100 on vc4).
> If you're going to set the scissor to the destination rectangle every
> time, you might as well also switch this to draw a single triangle
> instead of a quad?

Maybe?  That would be a separate change, at least.  And I'd rather see
us just fix the fact that we ever draw to the front buffer in general.

> Also, we use scissors all over the place; is this the only one which
> gains significantly on your hardware?

No, scissors are always a good idea for me, and the rest of the code
I've seen didn't try to optimize out turning on a scissor.
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