[Mesa-dev] [PATCH] i965: enable ARB_shader_precision

[Kenneth Graunke]

On Monday, May 16, 2016 3:11:12 PM PDT Alejandro Piñeiro wrote:
> At this moment the documentation says:
>   GL_ARB_shader_precision DONE (all drivers that support GLSL 4.10)
> 
> On the intel drivers, GLSLVersion is being updated based on the
> extensions being completed. So this patch just enables the
> extension for GLSLVersion >= 410.
> ---
> 
> Some extra info:
> 
> This was detected when doing a last test with the patch that
> expose 4.2 on the vertex_attrib_64bit thread. It assumed that
> 4.1 was already fulfilled, but ARB_shader_precision is still not
> beint exposed.
> 
> From the docs/GL3.txt:
>   GL_ARB_shader_precision                               DONE (all drivers 
that support GLSL 4.10)
> 
> And from the commit that made that change:
>     "This extension is about setting expectation on GL4.1 implementations
>     rather than actually enforcing things. So once you support GLSL 410
>     then you support this in theory."
> 
> On the intel driver, GLSLVersion is being updated as the extensions for
> each version are being completed. So I think that it is reasonable to
> just compare agains GLSLVersion >= 410, and enable the extension in that
> case, even if it is somewhat a circular reasoning.
> 
> We plan to update to GLSLVersion=420 as soon as we land the va64 patches.
> 
>  src/mesa/drivers/dri/i965/intel_extensions.c | 3 +++
>  1 file changed, 3 insertions(+)

I'd rather just enable the extension on Gen8+, and not bother looking at
the GLSL version.  I spent some time today running the tests.  It turns
out there was a bug in the tests:

https://lists.freedesktop.org/archives/piglit/2016-May/019802.html

With that fixed, we pass 100% of them.  I went ahead and pushed a patch
to enable the extension on Gen8+.

So, we should be good to go for 4.2 now.  Thanks for catching this!

--Ken
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