[Mesa-dev] [PATCH 12/18] glsl: Set the uniform_block index for the linked shader variables.

[Ian Romanick]

On 07/02/2012 05:38 PM, Eric Anholt wrote:
> At this point in the linking, we've totally lost track of the struct
> gl_uniform_buffer that this pointed to in the original unlinked
> shader, so we do a nasty n^2 walk to find it the new one based on the
> variable name.
>
> Note that these point into the shader's list of gl_uniform_buffers,
> not the linked program's.

And this works when a shader is linked to multiple programs because it's 
the copy of the original shader.  Right?

> ---
>   src/glsl/link_uniforms.cpp |   45 ++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 45 insertions(+)
>
> diff --git a/src/glsl/link_uniforms.cpp b/src/glsl/link_uniforms.cpp
> index dddac43..ff75b89 100644
> --- a/src/glsl/link_uniforms.cpp
> +++ b/src/glsl/link_uniforms.cpp
> @@ -27,6 +27,7 @@
>   #include "ir_uniform.h"
>   #include "glsl_symbol_table.h"
>   #include "program/hash_table.h"
> +#include "program.h"
>
>   /**
>    * \file link_uniforms.cpp
> @@ -377,6 +378,42 @@ link_cross_validate_uniform_block(void *mem_ctx,
>      return linked_block_index;
>   }
>
> +/**
> + * Walks the IR and update the references to uniform blocks in the
> + * ir_variables to point at linked shader's list (previously, they
> + * would point at the uniform block list in one of the pre-linked
> + * shaders).
> + */
> +static bool
> +link_update_uniform_buffer_variables(struct gl_shader *shader)
> +{
> +   foreach_list(node, shader->ir) {
> +      ir_variable *const var = ((ir_instruction *) node)->as_variable();
> +
> +      if ((var == NULL) || (var->uniform_block == -1))
> +	 continue;
> +
> +      assert(var->mode == ir_var_uniform);
> +
> +      bool found = false;
> +      for (unsigned i = 0; i < shader->NumUniformBlocks; i++) {
> +	 for (unsigned j = 0; j < shader->UniformBlocks[i].NumUniforms; j++) {
> +	    if (!strcmp(var->name, shader->UniformBlocks[i].Uniforms[j].Name)) {
> +	       found = true;
> +	       var->uniform_block = i;
> +	       var->location = j;
> +	       break;
> +	    }
> +	 }
> +	 if (found)
> +	    break;
> +      }
> +      assert(found);
> +   }
> +
> +   return true;
> +}
> +
>   void
>   link_assign_uniform_locations(struct gl_shader_program *prog)
>   {
> @@ -401,6 +438,14 @@ link_assign_uniform_locations(struct gl_shader_program *prog)
>       */
>      memset(prog->SamplerUnits, 0, sizeof(prog->SamplerUnits));
>
> +   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {
> +      if (prog->_LinkedShaders[i] == NULL)
> +	 continue;
> +
> +      if (!link_update_uniform_buffer_variables(prog->_LinkedShaders[i]))
> +	 return;
> +   }
> +
>      /* First pass: Count the uniform resources used by the user-defined
>       * uniforms.  While this happens, each active uniform will have an index
>       * assigned to it.
>