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

[Matt Turner]

On Tue, Dec 9, 2014 at 2:52 AM, Eduardo Lima Mitev <elima at igalia.com> 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");
>           }
> +         /* 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.

I'd snip the rest of the quote after this. I don't think it makes the
point clearer, and actually just makes it harder to see the important
bit.

> 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."
> +          *
> +          * 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.

I'd snip the quote before this.

> 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");

Try to line wrap this.

With those comments fixed:

Reviewed-by: Matt Turner <mattst88 at gmail.com>