[Mesa-dev] [WIP 00/13] GL_ARB_explicit_uniform_location extension

[Ian Romanick]

On 03/27/2014 11:45 PM, Tapani Pälli wrote:
> Hi;
> 
> Patches implement the extension, no Piglit regressions and all the tests
> for the extension pass (I've planned some more tests which are not yet
> in though).
> 
> Changes shortly:
> 
>    - opt_dead_code optimization is modifed to build a list of removed
>      uniform locations (that had explicit location) as this information
>      is required by the extension. For this I had to modify here and
>      there to have gl_shader_program structure available.
> 
>    - link_uniforms is modified to first occupy all explicit locations
>      and only then the rest (sorry about patch size but I'm having trouble
>      to split it smaller)
> 
>    - small parser changes, likely needs still more validation checks
> 
> I would need some help determining what kind of version checks (gl, glsl)
> should be made in the parser for this extension and also should I rather
> just enable it for everyone or only for Intel, would be cool if someone
> could test this implementation against some other platform.

The extension spec says, "Requires OpenGL 3.3 or
ARB_explicit_attrib_location."  I think we can enable it in every driver
that also enables ARB_explicit_attrib_location... according to
docs/GL3.txt, that's "all drivers that support GLSL."

> Also, I'm not sure how to actually get a good MAX_UNIFORM_LOCATIONS
> value, current one is just thrown with a dice. For example this is 65536
> for Nvidia binary driver (with gtx660) but it feels rather big to
> *really* work .. or?

I think this should be set based on GL_MAX_*_UNIFORM_COMPONENTS.  An
application should be able to set a location for every uniform.  The
worst that will happen if the value is huge is that the application will
ask us to waste a bunch of memory.  Applications already have a lot of
ways to ask us to waste memory. :)  If we encounter apps that, say, just
use locations 2 and 65534, then we can look at using a different data
structure to avoid the waste.

> Here's a branch with the patches:
> http://cgit.freedesktop.org/~tpalli/mesa/log/?h=exp_uniform_loc
> 
> Any comments appreciated, thanks;
> 
> // Tapani
> 
> 
> Tapani Pälli (13):
>   glapi: add GL_ARB_explicit_uniform_location
>   mesa: add enable bit for ARB_explicit_uniform_location
>   mesa: add new enum MAX_UNIFORM_LOCATIONS and default value
>   mesa: add a storage for inactive/removed uniform variables
>   glsl: change do_common_optimization signature
>   glsl: change do_dead_code signature, store uniform locations
>   glsl/linker: change link_assign_uniform_locations signature
>   glsl/linker: GL_ARB_explicit_uniform_location support
>   mesa: support inactive uniforms in glUniform* functions
>   glsl: add enable bit for ARB_explicit_uniform_location
>   glsl: parser changes for GL_ARB_explicit_uniform_location
>   intel: Enable GL_ARB_explicit_uniform_location
>   docs: update ARB_explicit_uniform_location status
> 
>  docs/GL3.txt                                 |   2 +-
>  src/glsl/ast_to_hir.cpp                      |  13 ++
>  src/glsl/glcpp/glcpp-parse.y                 |   3 +
>  src/glsl/glsl_lexer.ll                       |   1 +
>  src/glsl/glsl_parser_extras.cpp              |  11 +-
>  src/glsl/glsl_parser_extras.h                |   2 +
>  src/glsl/ir_optimization.h                   |   6 +-
>  src/glsl/ir_uniform.h                        |   5 +-
>  src/glsl/link_uniforms.cpp                   | 239 ++++++++++++++++++++++++---
>  src/glsl/linker.cpp                          |  12 +-
>  src/glsl/linker.h                            |   5 +-
>  src/glsl/opt_dead_code.cpp                   |  40 ++++-
>  src/mapi/glapi/gen/gl_API.xml                |   6 +
>  src/mesa/drivers/dri/i965/brw_shader.cpp     |   3 +-
>  src/mesa/drivers/dri/i965/intel_extensions.c |   1 +
>  src/mesa/main/context.c                      |   3 +
>  src/mesa/main/extensions.c                   |   1 +
>  src/mesa/main/get.c                          |   1 +
>  src/mesa/main/get_hash_params.py             |   1 +
>  src/mesa/main/mtypes.h                       |  19 +++
>  src/mesa/main/shaderobj.c                    |   7 +
>  src/mesa/main/tests/enum_strings.cpp         |   1 +
>  src/mesa/main/uniform_query.cpp              |  16 ++
>  src/mesa/program/ir_to_mesa.cpp              |   2 +-
>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp   |   3 +-
>  25 files changed, 367 insertions(+), 36 deletions(-)
>