[Mesa-dev] [RFC] Mesa 7.9 release criteria

Brian Paul brianp at vmware.com
Tue Aug 31 18:35:09 PDT 2010

On 08/31/2010 02:57 PM, Ian Romanick wrote:
> Hash: SHA1
> We'd still like to release Mesa 7.9 at the end of September.  That's
> four weeks from now.  As soon as the glsl2-loops branch lands (I'm
> expecting this to be this week), all of the major development on the new
> compiler will be complete.  There's still a fair amount of bug fixing to
> be done, but that feels like the stabilization phase leading up to a
> release.
> Looking at the result of a bugzilla search for "glsl" I see a few
> categories of bugs:
>   - Old bugs.  Everything before #29044 was filed before the glsl2 work.
>   This accounts for almost half of the bugs (35 of 72).
>   - Bugs that only occur on softpipe or llvmpipe.  Since these bugs
> aren't reproducible in swrast, i965, or r300c, my first guess is that
> the problem is either in the Gallium code or the Mesa IR to TGSI
> translation layer.  Someone familiar with that code is going to have to
> do *some* leg work here.  It may not be (as was the case with reads from
> shader outputs), but I don't have the information to determine that.

I'm trying to look at some of these in my spare time.  But it's really 
easy to run the gallium softpipe driver, as Dave said.

>   - Additional regressions in applications that weren't completely
> correct with the old compiler.  As far as I'm aware, the regressions in
> the Humus and Unigen demos are all added failures.
>   - Lack of noise support.  This is really only an issue for swrast.  As
> far as I'm aware, none of the hardware drivers actually support the
> noise opcode generated by the old compiler.  Our plan here is to
> implement noise in GLSL.  There are a couple issues with that,
> especially on old chips like r300 and i915, and it doesn't seem like a
> high priority.
>   - A small number of assertion failures.  I think #29573 and #29687 are
> the only ones left.  I believe Eric is working on these.
> Looking at this, it seems like it won't take too much work to have
> things in much, much better shape with the new compiler than they were
> in with the old compiler.  Even if it's not quite perfect, and it won't
> be, getting a release out is a good thing.
> So... what are our collective criteria for a 7.9 release to happen?

Ian, I'm still getting up to speed on the new compiler, but it looks 
like a full 4-element temp/const vector is allocated for each GLSL 
float.  The previous compiler would try to pack four floats into a 
single vector whenever possible.  This could dramatically reduced the 
number of vector temps/consts needed.

I'm worried that some apps that use large shaders will start failing.


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