[Mesa-dev] wider registers in llvmpipe

Jose Fonseca jfonseca at vmware.com
Tue Jul 17 05:57:37 PDT 2012

----- Original Message -----
> FYI, I've just pushed a branch named llvmpipe-wider-regs, which
> allows llvmpipe to leverage SIMD registers wider than 128bits.
> Unfortunately, performance-wise this doesn't change much, as llvmpipe
> performance is dominated by integer SIMD instructions, whereas
> currently the AVX instruction set currently only supports floating
> SIMD instructions.  Actually, often things will get slightly slower,
> as there are considerable overheads in piecing together the 256
> floating point code paths and 128-bit integer code paths.
> The benefit for this change is foremost architectural: llvmpipe now
> makes less assumptions regarding the number of pixels/quads/etc that
> fit into a hardware register, a flexibility which will be necessary
> to get things like per-pixel LOD working properly.
> This barely touch files outside gallivm/draw/llvmpipe modules. I
> haven't tested i915g, r300g, so let me know if there are regressions
> / concerns. I'd like to merge this into master soon.

I went ahead and pushed, after doing more testing. If there's any regression on any driver as consequence just let me know.


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