[Mesa-dev] atan2 piglit failures since commit d877c643b

[Matt Turner]

On Sat, Apr 19, 2014 at 8:26 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> Hi Matt,
>
> Starting with commit d877c643b ("glsl: Use M_PI_* macros."), I'm
> seeing a few piglit failures on nvcf (GF116) for
>
> generated_tests/spec/glsl-1.10/execution/built-in-functions/fs-atan-vec2-vec2.shader_test

Strange. They all pass for me on Haswell before and after the change.

> and its vs/gs counterparts. Curiously it works fine on nv50-family
> chips. I checked the generated shaders, and the only differences are
> the constants[1]. Does the generated test need to be adjusted to
> expect more (or less) precise values perhaps? Or is it likely that
> there's some bug in the shader that was being masked by the less
> correct constants?
>
> I haven't actually looked at the atan formula -- could it be that
> those constants were "off" on purpose? Any other ideas?

No, Paul's commit message for d4c80f5f confirms the constants.

That only some of combinations fail for you makes me think it's
something driver specific that this patch unwittingly uncovered.