[Mesa-dev] [PATCH] glsl: Generate compile errors for explicit blend indices < 0 or > 1.

[Paul Berry]

On 31 August 2012 16:04, Kenneth Graunke <kenneth at whitecape.org> wrote:

> According to the GLSL 4.30 specification, this is a compile time error.
> Earlier specifications don't specify a behavior, but since 0 and 1 are
> the only valid indices for dual source blending, it makes sense to
> generate the error.
>
> Fixes (the fixed version of) piglit's layout-12.frag.
>
> NOTE: This is a candidate for the 9.0 branch.
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/glsl/ast_to_hir.cpp | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
> index 02fe66b..becf6f9 100644
> --- a/src/glsl/ast_to_hir.cpp
> +++ b/src/glsl/ast_to_hir.cpp
> @@ -2086,9 +2086,22 @@ apply_type_qualifier_to_variable(const struct
> ast_type_qualifier *qual,
>          } else {
>             var->location = qual->location;
>          }
> +
>          if (qual->flags.q.explicit_index) {
> -           var->explicit_index = true;
> -           var->index = qual->index;
> +            /* From the GLSL 4.30 specification: "It is also a
> compile-time
> +             * error if a fragment shader sets a layout index to less
> than 0
> +             * or greater than 1."
>

Minor nit pick: would you mind referencing the section of the spec this
quote comes from (4.4.2 Output Layout Qualifiers)?

Other than that, this patch is:

Reviewed-by: Paul Berry <stereotype441 at gmail.com>


> +             *
> +             * Older specifications don't mandate a behavior; we take this
> +             * as a clarification and always generate the error.
> +             */
> +            if (qual->index < 0 || qual->index > 1) {
> +               _mesa_glsl_error(loc, state,
> +                                "explicit index may only be 0 or 1\n");
> +            } else {
> +               var->explicit_index = true;
> +               var->index = qual->index;
> +            }
>          }
>        }
>     } else if (qual->flags.q.explicit_index) {
> --
> 1.7.11.4
>
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