[Mesa-dev] Rework use of gl program structures

[Timothy Arceri]

Series is available in the free_gl_linked_shader6 branch of:

https://github.com/tarceri/Mesa.git

On Fri, 2016-11-11 at 11:45 +1100, Timothy Arceri wrote:
> I started out with a goal of freeing _LinkedShaders after linking as
> this
> would have allowed a bunch of code simplification and also reduced
> the
> possibility of subtle bugs in i965 where a program that is currently
> active is relinked but fails and then we recompile a variant of the
> still
> active program but we would have lost things such as per stage atomic
> bindings which would be deleted during the failed relink.
> 
> In the end this series grew larger than expected so for now this
> series
> aims to switch the pipeline objects CurrentProgram array from using
> gl_shader_program to gl_program. Previously the CurrentProgram array
> could have contained multiple pointers to the same struct which was
> confusing and we would often need to fish out the information we were
> really after from the gl_program anyway. Using gl_program makes much
> more sense and allows us to optimise some critical paths such as SSO
> and sampler validation which are called at draw time.
> 
> In patch 68 when we finally change the pointers used in
> CurrentProgram
> you can see some of the confusion caused by the old way of doing
> things
> where use_shader_program() calls 
> _mesa_shader_program_init_subroutine_defaults() on each stage in
> gl_shader_program but we also call use_shader_program() itself for
> each stage in gl_shader_program so unless we are dealing with single
> stage SSO programs we will initialise subroutine defaults many
> times over. 
> 
> Patch 11 is noteworthy as it creates a gl_program at the start of
> linking which allows us to just set values directly rather than
> copying them from gl_linked_shader at a later time. Patch 55 is
> a good example of one of the many clean-ups this allows.
> 
> On top of all this these changes should help make shader cache
> cleaner
> (once I get around to rebasing and fixing it) and hopefully resolve
> some of the problems I was having figuring out how to get it working
> for SSO.
> 
> I've tried to make the order of the patchs make sense for reviewing
> but since almost everything is working towards the last 3 patches
> reviewers may need to jump to the last few patches at times.
> 
> Finally the last 3 patches will need to be squashed to stop
> compilation errors I've just split them up to help make reviewing
> easier. I would have liked to have made patch 69 separate but the
> patches have some circular dependencies that made it difficult.
> 
> I'm really happy with how this series turned out and the improvements
> I was able to make along the way. Please review.
> 
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