[Mesa-dev] [PATCH 1/2] glsl: Fix redeclaration rules for gl_FragCoord.

[Chris Forbes]

Correct, this doesn't try to tackle the link-time cases at all.

After sending these out, Anuj told me that he had similar patches
pending review. Unfortunate to duplicate effort, but it's what I get
for doing a bunch of random bug-stomping, I guess :)

Hopefully we can pick the best ideas from both series.

On Thu, Apr 17, 2014 at 6:29 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> On 04/12/2014 10:30 PM, Chris Forbes wrote:
>> The ARB_fragment_coord_conventions spec, section 4.3.x (Input Layout
>> Qualifiers) says:
>>
>>   "All redeclarations of gl_FragCoord in all fragment shaders in a
>>   single program must have the same set of qualifiers. Within any
>>   shader, the first redeclarations of gl_FragCoord must appear before
>>   any use of gl_FragCoord."
>>
>> Fixes piglit's tests:
>>    arb_fragment_coord_conventions/compiler/redeclaration-after-use
>>    arb_fragment_coord_conventions/compiler/redeclaration-around-use
>>    glsl-1.50/compiler/fragment_coord_conventions/layout-qualifiers-conflicting-case-1
>>    glsl-1.50/compiler/fragment_coord_conventions/layout-qualifiers-conflicting-case-2
>>
>> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
>> ---
>>  src/glsl/ast_to_hir.cpp | 20 ++++++++++++++++++++
>>  1 file changed, 20 insertions(+)
>>
>> diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
>> index 9b9d511..d1eb3e2 100644
>> --- a/src/glsl/ast_to_hir.cpp
>> +++ b/src/glsl/ast_to_hir.cpp
>> @@ -2715,9 +2715,29 @@ get_variable_being_redeclared(ir_variable *var, YYLTYPE loc,
>>        /* Allow redeclaration of gl_FragCoord for ARB_fcc layout
>>         * qualifiers.
>>         */
>> +
>> +      if (earlier->data.how_declared != ir_var_declared_implicitly
>> +          && (earlier->data.origin_upper_left != var->data.origin_upper_left
>> +             || earlier->data.pixel_center_integer != var->data.pixel_center_integer)) {
>> +         _mesa_glsl_error(&loc, state,
>> +                          "Inconsistent redeclarations of gl_FragCoord");
>> +      }
>> +
>>        earlier->data.origin_upper_left = var->data.origin_upper_left;
>>        earlier->data.pixel_center_integer = var->data.pixel_center_integer;
>>
>> +      if (earlier->data.used &&
>> +          earlier->data.how_declared == ir_var_declared_implicitly) {
>> +         /* ARB_fragment_coord_conventions spec Section 4.3.x.1
>> +          * (Input Layout Qualifier) says:
>> +          *
>> +          * "Within any shader, the first redeclarations of gl_FragCoord
>> +          * must appear before any use of gl_FragCoord."
>> +          */
>> +         _mesa_glsl_error(&loc, state,
>> +                          "First redeclaration of gl_FragCoord must appear before any use");
>> +      }
>> +
>>        /* According to section 4.3.7 of the GLSL 1.30 spec,
>>         * the following built-in varaibles can be redeclared with an
>>         * interpolation qualifier:
>>
>
> It seems like this will catch multiple, inconsistent redeclarations
> within a single fragment shader...but the spec text quoted indicates
> that redeclarations in all fragment shaders being linked together into a
> single program need to be consistent.
>
> I don't see any code to handle that in linker*.cpp, so presumably we
> ought to add that as well.  Regardless, this is a good improvement!
>
> Both patches are:
> Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
>
> Thanks, Chris.
>