[Mesa-dev] [PATCH] glsl: extend GLSLSkipStrictMaxUniformLimitCheck to uniform block size

[Ian Romanick]

On 04/11/2015 09:48 AM, Marcin Ślusarz wrote:
> ARB_uniform_buffer_object spec says:
> "The total amount of buffer object storage available for any given uniform
> block is subject to an implementation-dependent limit; the maximum amount
> of available space, in basic machine units, can be queried by calling
> GetIntegerv with the constant MAX_UNIFORM_BLOCK_SIZE.  If the amount
> of storage required for a uniform block exceeds this limit, a program may
> fail to link."
> 
> Fixes these piglit tests:
> spec at arb_uniform_buffer_object@maxuniformblocksize at fsexceed
> spec at arb_uniform_buffer_object@maxuniformblocksize at vsexceed
> on nouveau/gk107.

Can you elaborate on how this fixes the test?  The fsexceed and vsexceed
tests are supposed to pass if linking fails.

> ---
>  src/glsl/linker.cpp | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
> index 85830e6..88a4548 100644
> --- a/src/glsl/linker.cpp
> +++ b/src/glsl/linker.cpp
> @@ -2308,6 +2308,25 @@ check_resources(struct gl_context *ctx, struct gl_shader_program *prog)
>                           _mesa_shader_stage_to_string(i));
>           }
>        }
> +
> +      for (unsigned j = 0; j < sh->NumUniformBlocks; ++j) {
> +         if (sh->UniformBlocks[j].UniformBufferSize >
> +                  ctx->Const.MaxUniformBlockSize) {
> +            if (ctx->Const.GLSLSkipStrictMaxUniformLimitCheck) {
> +               linker_warning(prog,
> +                              "%s shader uses uniform block whose size exceeds "
> +                              "MAX_UNIFORM_BLOCK_SIZE, but the driver will try "
> +                              "to optimize them out; this is non-portable "
> +                              "out-of-spec behaviour\n",
> +                              _mesa_shader_stage_to_string(i));
> +            } else {
> +               linker_error(prog,
> +                            "%s shader uses uniform block whose size exceeds "
> +                            "MAX_UNIFORM_BLOCK_SIZE\n",
> +                            _mesa_shader_stage_to_string(i));
> +            }
> +         }
> +      }
>     }
>  
>     unsigned blocks[MESA_SHADER_STAGES] = {0};
>