[Piglit] [PATCH 00/11] Lots of UBO tests

Ian Romanick idr at freedesktop.org
Tue Sep 9 11:18:11 PDT 2014

On 09/08/2014 02:34 PM, Ian Romanick wrote:
> A couple weeks ago I told Dave Airlie that I was working on a giant pile
> UBO tests.  This is not that work, but it is most of the changes to get
> ready for that work.  The first three patches were written quite some
> time ago while fixing bugs in Mesa's UBO code.  The remainder were
> developed while working on my UBO test generator script.
> The test generator script effort has been slowed by many bugs in various
> UBO implementations.  I have recently submitted several Mesa bugs
> (listed below) that were discovered by this work.
> https://bugs.freedesktop.org/show_bug.cgi?id=83468
> https://bugs.freedesktop.org/show_bug.cgi?id=83506
> https://bugs.freedesktop.org/show_bug.cgi?id=83508
> https://bugs.freedesktop.org/show_bug.cgi?id=83533
> I have also found numerous issues in NVIDIA's closed source driver:
> - Global layout qualifiers are ignored.
>     layout(row_major) uniform;
>     uniform U { mat4 m; }; // m will be column-major
> - Layout qualifiers on structures are ignored.
>     struct S { mat4 m; };
>     uniform U { layout(row_major) S s; }; // s.m will be column-major
> - Small structures are not padded to vec4-size.  See patch #8.
> It seems like there was a 4th bug, but I can't remember what it was.

We've done some testing on AMD closed source drivers now, and we have
found that they have a non-overlapping set of bugs.  Testing is a bit
blocked on one bug:

- Block members that are not used in the shader (e.g., "active") are not
reported by the GL API.

This bug makes a very large number of tests fail.  I intentionally don't
probe every member of ever block because... Mesa's GLSL compiler takes
massive amounts of time linking those shaders.  I suspect the time may
be in code generator or optimization passes.  Dunno yet.

> As a result, I don't have access to a correct implementation to verify
> my script... which generates random tests.  I have to scrutinize each
> failing test that is generated to determine whether the script or driver
> is at fault.  Anyway... should get something out RSN.
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