[Mesa-dev] [PATCH 2/3] glsl: Lower UBO and SSBO access in glsl linker

[Timothy Arceri]

On Wed, 2015-11-04 at 15:33 -0800, Kristian Høgsberg Kristensen wrote:
> All GLSL IR consumers run this lowering pass so we can move it to the
> linker. This moves the pass up quite a bit, but that's the point: it
> needs to run before we throw away information about per-component vector
> access.
> 
> Signed-off-by: Kristian Høgsberg Kristensen <krh at bitplanet.net>
> ---
>  src/glsl/linker.cpp                        | 8 ++++++++
>  src/mesa/drivers/dri/i965/brw_link.cpp     | 2 --
>  src/mesa/drivers/dri/i965/brw_shader.cpp   | 2 ++
>  src/mesa/main/mtypes.h                     | 2 ++
>  src/mesa/state_tracker/st_extensions.c     | 1 +
>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 1 -
>  6 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
> index c35d87a..ea6a3f3 100644
> --- a/src/glsl/linker.cpp
> +++ b/src/glsl/linker.cpp
> @@ -4449,6 +4449,14 @@ link_shaders(struct gl_context *ctx, struct
> gl_shader_program *prog)
>  
>     /* FINISHME: Assign fragment shader output locations. */
>  
> +   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
> +      if (prog->_LinkedShaders[i] == NULL)
> +	 continue;
> +
> +      if (ctx->Const.ShaderCompilerOptions[i].LowerBufferInterfaceBlocks)
> +         lower_ubo_reference(prog->_LinkedShaders[i]);
> +   }
> +
>  done:
>     for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
>        free(shader_list[i]);
> diff --git a/src/mesa/drivers/dri/i965/brw_link.cpp
> b/src/mesa/drivers/dri/i965/brw_link.cpp
> index f1e3860..2991173 100644
> --- a/src/mesa/drivers/dri/i965/brw_link.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_link.cpp
> @@ -157,8 +157,6 @@ process_glsl_ir(gl_shader_stage stage,
>                   _mesa_shader_stage_to_abbrev(shader->Stage));
>     }
>  
> -   lower_ubo_reference(shader);
> -
>     bool progress;
>     do {
>        progress = false;
> diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp
> b/src/mesa/drivers/dri/i965/brw_shader.cpp
> index 4ea297a..5adc986 100644
> --- a/src/mesa/drivers/dri/i965/brw_shader.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
> @@ -148,6 +148,8 @@ brw_compiler_create(void *mem_ctx, const struct
> brw_device_info *devinfo)
>           compiler->glsl_compiler_options[i].EmitNoIndirectSampler = true;
>  
>        compiler->glsl_compiler_options[i].NirOptions = nir_options;
> +
> +      compiler->glsl_compiler_options[i].LowerBufferInterfaceBlocks = true;
>     }
>  
>     return compiler;
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index d6c1eb8..800ad81 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -2874,6 +2874,8 @@ struct gl_shader_compiler_options
>      */
>     GLboolean OptimizeForAOS;
>  
> +   GLboolean LowerBufferInterfaceBlocks; /**< Lower UBO and SSBO access to
> intrinsics. */
> +

Does it even matter if this pass was to run for drivers that don't support
UBO/SSBO? 

I assume all other drivers would want to run this pass, in which case is it
really helpful to a this flag?

>     const struct nir_shader_compiler_options *NirOptions;
>  };
>  
> diff --git a/src/mesa/state_tracker/st_extensions.c
> b/src/mesa/state_tracker/st_extensions.c
> index bd7cbcc..bbb9027 100644
> --- a/src/mesa/state_tracker/st_extensions.c
> +++ b/src/mesa/state_tracker/st_extensions.c
> @@ -254,6 +254,7 @@ void st_init_limits(struct pipe_screen *screen,
>                                       
>  PIPE_SHADER_CAP_MAX_UNROLL_ITERATIONS_HINT);
>  
>        options->LowerClipDistance = true;
> +      options->LowerBufferInterfaceBlocks = true;
>     }
>  
>     c->LowerTessLevel = true;
> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> index ca00930..9ee6f8f 100644
> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> @@ -5822,7 +5822,6 @@ st_link_shader(struct gl_context *ctx, struct
> gl_shader_program *prog)
>                           (!ctx->Const.NativeIntegers ? INT_DIV_TO_MUL_RCP :
> 0) |
>                           (options->EmitNoSat ? SAT_TO_CLAMP : 0));
>  
> -      lower_ubo_reference(prog->_LinkedShaders[i]);
>        do_vec_index_to_cond_assign(ir);
>        lower_vector_insert(ir, true);
>        lower_quadop_vector(ir, false);