[Mesa-dev] [PATCH] glsl: don't allow invariant qualifiers for interface blocks

[Ian Romanick]

On 12/09/2014 02:52 AM, Eduardo Lima Mitev wrote:
> From: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
> 
> GLSL 1.50 and GLSL 4.40 specs, they both say the same in
> "Interface Blocks" section:
> 
> "If no optional qualifier is used in a member-declaration, the qualification of
> the member includes all in, out, patch, uniform, or buffer as determined by
> interface-qualifier. If optional qualifiers are used, they can include
> interpolation qualifiers, auxiliary storage qualifiers, and storage qualifiers
> and they must declare an input, output, or uniform member consistent with the
> interface qualifier of the block"
> 
> From GLSL ES 3.0, chapter 4.3.7 "Interface Blocks", page 38:
> 
> "GLSL ES 3.0 does not support interface blocks for shader inputs or outputs."
> 
> and from GLSL ES 3.0, chapter 4.6.1 "The invariant qualifier", page 52.
> 
> "Only variables output from a shader can be candidates for invariance. This
> includes user-defined output variables and the built-in output variables. As
> only outputs can be declared as invariant, an invariant output from one shader
> stage will still match an input of a subsequent stage without the input being
> declared as invariant."
> 
> From GLSL ES 1.0, chapter 4.6.1 "The invariant qualifier", page 37.
> 
> "Only the following variables may be declared as invariant:
> * Built-in special variables output from the vertex shader
> * Varying variables output from the vertex shader
> * Built-in special variables input to the fragment shader
> * Varying variables input to the fragment shader
> * Built-in special variables output from the fragment shader."
> 
> This patch fixes the following dEQP tests:
> 
> dEQP-GLES3.functional.shaders.declarations.invalid_declarations.invariant_uniform_block_2_vertex
> dEQP-GLES3.functional.shaders.declarations.invalid_declarations.invariant_uniform_block_2_fragment
> 
> No piglit regressions.
> 
> Signed-off-by: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
> 
> v2:
> 
> - Enable this check for GLSL.
> 
> Signed-off-by: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
> ---
>  src/glsl/glsl_parser.yy | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/src/glsl/glsl_parser.yy b/src/glsl/glsl_parser.yy
> index 7fb8c38..9f2a0a3 100644
> --- a/src/glsl/glsl_parser.yy
> +++ b/src/glsl/glsl_parser.yy
> @@ -2539,6 +2539,41 @@ basic_interface_block:
>                               "interface block member does not match "
>                               "the interface block");
>           }

Blank line here.

> +         /* From GLSL ES 3.0, chapter 4.3.7 "Interface Blocks", page 38:
> +          *
> +          * "GLSL ES 3.0 does not support interface blocks for shader inputs or
> +          * outputs."
> +          *
> +          * And from GLSL ES 3.0, chapter 4.6.1 "The invariant qualifier", page 52.
> +          *
> +          * "Only variables output from a shader can be candidates for
> +          * invariance. This includes user-defined output variables and the
> +          * built-in output variables. As only outputs can be declared as
> +          * invariant, an invariant output from one shader stage will
> +          * still match an input of a subsequent stage without the input being
> +          * declared as invariant."
> +          *
> +          * From GLSL ES 1.0, chapter 4.6.1 "The invariant qualifier", page 37.
> +          *
> +          * "Only the following variables may be declared as invariant:
> +          *  * Built-in special variables output from the vertex shader
> +          *  * Varying variables output from the vertex shader
> +          *  * Built-in special variables input to the fragment shader
> +          *  * Varying variables input to the fragment shader
> +          *  * Built-in special variables output from the fragment shader."

In addition to Matt's comments about the comment...

I don't think there's any reason to mention GLSL ES 1.0.  There are no
interface blocks in GLSL ES 1.0, and this is inside processing an
interface block.

With this and Matt's suggestions applied, this patch is

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

> +          *
> +          * From GLSL 4.40 and GLSL 1.50, section "Interface Blocks":
> +          *
> +          * "If no optional qualifier is used in a member-declaration, the
> +          * qualification of the member includes all in, out, patch, uniform,
> +          * or buffer as determined by interface-qualifier. If optional
> +          * qualifiers are used, they can include interpolation qualifiers,
> +          * auxiliary storage qualifiers, and storage qualifiers and they must
> +          * declare an input, output, or uniform member consistent with the
> +          * interface qualifier of the block"
> +          */
> +         if (qualifier.flags.q.invariant)
> +            _mesa_glsl_error(&@1, state, "invariant qualifiers cannot be used with interface blocks members");
>        }
>  
>        $$ = block;
>