[Mesa-dev] [PATCH] glsl: Only allow `invariant` on shader in/out between stages.

[Chris Forbes]

The FINISHME comment is a relic from another time, before shader
inputs and function inputs were split. Removed.

Marked for 10.0/10.1 and pushed with Ian's r-b from IRC

On Mon, Apr 21, 2014 at 4:06 PM, Chris Forbes <chrisf at ijw.co.nz> wrote:
> Previously this was special-cased for VS and FS; it never got updated
> when geometry shaders came along. Generalize using is_varying_var() so
> this won't be broken again with tessellation.
>
> Note that there are two copies of the logic for `invariant`: It can be
> present as part of a new declaration, and also as a redeclaration of an
> existing variable or block member.
>
> Fixes the four new piglits:
>    specc/glsl-1.50/compiler/invariant-qualifier-*.geom
>
> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
> ---
>  src/glsl/ast_to_hir.cpp | 34 +++++++++++-----------------------
>  1 file changed, 11 insertions(+), 23 deletions(-)
>
> diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
> index 35d58e9..e4f3f77 100644
> --- a/src/glsl/ast_to_hir.cpp
> +++ b/src/glsl/ast_to_hir.cpp
> @@ -3065,16 +3065,10 @@ ast_declarator_list::hir(exec_list *instructions,
>              _mesa_glsl_error(& loc, state,
>                               "undeclared variable `%s' cannot be marked "
>                               "invariant", decl->identifier);
> -         } else if ((state->stage == MESA_SHADER_VERTEX)
> -                    && (earlier->data.mode != ir_var_shader_out)) {
> -            _mesa_glsl_error(& loc, state,
> -                             "`%s' cannot be marked invariant, vertex shader "
> -                             "outputs only", decl->identifier);
> -         } else if ((state->stage == MESA_SHADER_FRAGMENT)
> -                    && (earlier->data.mode != ir_var_shader_in)) {
> -            _mesa_glsl_error(& loc, state,
> -                             "`%s' cannot be marked invariant, fragment shader "
> -                             "inputs only", decl->identifier);
> +         } else if (!is_varying_var(earlier, state->stage)) {
> +            _mesa_glsl_error(&loc, state,
> +                             "`%s' cannot be marked invariant; interfaces between "
> +                             "shader stages only.", decl->identifier);
>           } else if (earlier->data.used) {
>              _mesa_glsl_error(& loc, state,
>                              "variable `%s' may not be redeclared "
> @@ -3250,19 +3244,13 @@ ast_declarator_list::hir(exec_list *instructions,
>                                        & loc, false);
>
>        if (this->type->qualifier.flags.q.invariant) {
> -         if ((state->stage == MESA_SHADER_VERTEX) &&
> -             var->data.mode != ir_var_shader_out) {
> -            _mesa_glsl_error(& loc, state,
> -                             "`%s' cannot be marked invariant, vertex shader "
> -                             "outputs only", var->name);
> -         } else if ((state->stage == MESA_SHADER_FRAGMENT) &&
> -                    var->data.mode != ir_var_shader_in) {
> -            /* FINISHME: Note that this doesn't work for invariant on
> -             * a function signature inval
> -             */
> -            _mesa_glsl_error(& loc, state,
> -                             "`%s' cannot be marked invariant, fragment shader "
> -                             "inputs only", var->name);
> +         /* FINISHME: Note that this doesn't work for invariant on
> +          * a function signature inval
> +          */
> +         if (!is_varying_var(var, state->stage)) {
> +            _mesa_glsl_error(&loc, state,
> +                             "`%s' cannot be marked invariant; interfaces between "
> +                             "shader stages only", var->name);
>           }
>        }
>
> --
> 1.9.2
>