[Mesa-dev] [PATCH v2 2/2] glsl: raise warning when using uninitialized variables

[Ilia Mirkin]

On Mon, Mar 28, 2016 at 2:50 PM, Alejandro Piñeiro <apinheiro at igalia.com> wrote:
> v2:
>  * Take into account out varyings too (Timothy Arceri)
>  * Fix style (Timothy Arceri)
>  * Use a new ast_expression variable, instead of an
>    ast_expression::hir new parameter (Timothy Arceri)
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94129
> ---
>  src/compiler/glsl/ast_to_hir.cpp | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
> index eb45f29..e38ab10 100644
> --- a/src/compiler/glsl/ast_to_hir.cpp
> +++ b/src/compiler/glsl/ast_to_hir.cpp
> @@ -1901,6 +1901,13 @@ ast_expression::do_hir(exec_list *instructions,
>        if (var != NULL) {
>           var->data.used = true;
>           result = new(ctx) ir_dereference_variable(var);
> +
> +         if ((var->data.mode == ir_var_auto || var->data.mode == ir_var_shader_out)
> +             && !this->is_lhs
> +             && result->variable_referenced()->data.assigned != true) {
> +            _mesa_glsl_warning(&loc, state, "`%s' used uninitialized",
> +                               this->primary_expression.identifier);

This also appears to warn in the case of

void foo(out float x) { x = 1.0; }

float bar;
foo(bar);

It thinks that bar is being used uninitialized. How do we fix this? It
happens a ton in Talos Principle.

  -ilia