[Mesa-dev] [PATCH 13/13] i965: disable loop unrolling in GLSL IR

[Matt Turner]

On Wed, Dec 21, 2016 at 8:26 PM, Timothy Arceri
<timothy.arceri at collabora.com> wrote:
> There is a single regression in loop unrolling which is:
>
> loops HURT:   shaders/orbital_explorer.shader_test GS SIMD8:    0 -> 1
>
> However the loop is huge so it seems reasonable not to unroll it. It's
> surprising that GLSL IR does unroll it.

Heh, that's funny. Orbital Explorer's GS doesn't have a loop in the
GLSL source. I believe it appears in the IR because we implement
"switch" with a loop (see commit
73dd50acf6d244979c2a657906aa56d3ac60d550). If that is the case, I am
surprised that we're able to unroll it since it has multiple breaks.
That would be interesting to investigate, but Orbital Explorer is
certainly not a case we should optimize for. :)