[Piglit] [PATCH] arb_enhanced_layouts: add test for location aliasing with non-numerical type

[Timothy Arceri]

On 09/11/17 18:52, Iago Toral wrote:
> This is not so much based on the spec but based on the original code we
> had in the linker (which we still have) which assumes that all
> locations consumed by a struct variable use up all 4 components (thus
> preventing any kind of aliasing to be successful) based on the fact
> that the component layout qualifier can't be used on structs (or its
> members):
> 
> if (type->without_array()->is_record()) {
>     /* The component qualifier can't be used on structs so just treat
>      * all component slots as used.
>      */
>     last_comp = 4;
> } else {
>     ...
> }
> 
> However, thinking a bit more about it, it is not 100% clear that this
> assumption is correct and maybe we should be doing the same for structs
> that I did for interface blocks members and check the actual components
> used by each field member and only produce link errors if there is
> actual component aliasing.

Yeah I wrote that code but looking at it now I'm not sure if its 
correct. The problem with structs is nesting, it could get very 
complicated trying to figure out packing with a struct.

> 
> Let's drop this patch for now.
> 
> Iago
> 
> On Thu, 2017-11-09 at 12:43 +1100, Timothy Arceri wrote:
>> On 06/11/17 23:22, Iago Toral Quiroga wrote:
>>> This is not allowed so we check that we produce a linker error.
>>
>> It's not 100% obvious why this wouldn't be allowed. Can we have a
>> spec
>> quote added to the
>>   test header?
>>
>>> ---
>>>    .../vs-to-fs-type-not-numerical.shader_test        | 52
>>> ++++++++++++++++++++++
>>>    1 file changed, 52 insertions(+)
>>>    create mode 100644
>>> tests/spec/arb_enhanced_layouts/linker/component-layout/vs-to-fs-
>>> type-not-numerical.shader_test
>>>
>>> diff --git a/tests/spec/arb_enhanced_layouts/linker/component-
>>> layout/vs-to-fs-type-not-numerical.shader_test
>>> b/tests/spec/arb_enhanced_layouts/linker/component-layout/vs-to-fs-
>>> type-not-numerical.shader_test
>>> new file mode 100644
>>> index 000000000..aede6ce8d
>>> --- /dev/null
>>> +++ b/tests/spec/arb_enhanced_layouts/linker/component-layout/vs-
>>> to-fs-type-not-numerical.shader_test
>>> @@ -0,0 +1,52 @@
>>> +# Test for link error between vertex and fragment shaders when
>>> +# component qualifiers don't match. This case checks that
>>> +# location aliasing is not permitted for non-numerical types
>>> +# such as a struct
>>> +
>>> +[require]
>>> +GLSL >= 3.30
>>> +GL_ARB_enhanced_layouts
>>> +GL_ARB_separate_shader_objects
>>> +
>>> +[vertex shader]
>>> +#version 330
>>> +#extension GL_ARB_enhanced_layouts: require
>>> +#extension GL_ARB_separate_shader_objects: require
>>> +
>>> +struct S {
>>> +  vec3 foo;
>>> +  vec4 bar;
>>> +};
>>> +
>>> +layout(location = 0, component = 3) out float b;
>>> +layout(location = 0) out S a;
>>> +
>>> +void main()
>>> +{
>>> +  a.foo = vec3(1.0);
>>> +  a.bar = vec4(1.0);
>>> +  b = 0.5;
>>> +}
>>> +
>>> +[fragment shader]
>>> +#version 330
>>> +#extension GL_ARB_enhanced_layouts: require
>>> +#extension GL_ARB_separate_shader_objects: require
>>> +
>>> +struct S {
>>> +  vec3 foo;
>>> +  vec4 bar;
>>> +};
>>> +
>>> +layout(location = 0, component = 3) in float b;
>>> +layout(location = 0) in S a;
>>> +
>>> +out vec4 color;
>>> +
>>> +void main()
>>> +{
>>> +  color = vec4(a.foo + a.bar.xyz, b);
>>> +}
>>> +
>>> +[test]
>>> +link error
>>>
>>
>>