[Intel-gfx] Low performance for trapezoid-heavy stuff

[Clemens Eisserer]

Hi,

> trapezoids are not accelerated right now. So there happens ping-pong between
> gpu and cpu which pains. Eric told that he may add trapezoid accel sooner or
> later.
Trapezoids also haven't been accelerated for EXA.

I suspect that some type of unoptimal cache setting slows down memory
access for the software-rendering routines.

- Clemens