On 10/15/2013 01:58 PM, Ian Romanick wrote:
> On 10/15/2013 01:50 PM, Anuj Phogat wrote:
>> On Tue, Oct 15, 2013 at 10:02 AM, Ian Romanick <i...@freedesktop.org> wrote:
>>> On 10/14/2013 10:12 AM, Anuj Phogat wrote:
>>>> @@ -789,6 +794,12 @@ builtin_variable_generator::generate_fs_special_vars()
>>>> if (state->AMD_shader_stencil_export_warn)
>>>> var->warn_extension = "GL_AMD_shader_stencil_export";
>>>> }
>>>> +
>>>> + if (state->ARB_sample_shading_enable) {
>>>> + add_input(VARYING_SLOT_SAMPLE_ID, int_t, "gl_SampleID");
>>>> + add_input(VARYING_SLOT_SAMPLE_POS, vec2_t, "gl_SamplePosition");
>>>> + add_output(FRAG_RESULT_SAMPLE_MASK, array(int_t, 1),
>>>> "gl_SampleMask");
>>>
>>> I don't see code anywhere in this patch series that correctly sizes this
>>> array. I thought gl_SampleMask.length() == gl_NumSamples... except you
>>> can't use .length() on gl_SampleMask because the size can't be known at
>>> compile-time. We should have a test that 'gl_SampleMask.length()' fails
>>> to compile. :)
>>>
>> I'll add a piglit compiler test for that.
>>
>>> The only other array that works like this is gl_TexCoord. That array is
>>> sized to 0 (line 837 of builtin_variables.cpp). I believe gl_SampleMask
>>> should do the same.
>>>
>> Yes, I noticed gl_TexCoord is using array size of 0 and it works for
>> gl_SampleMask as well. But, It generates same glsl ir with array size
>> of 0 or 1:
>> (declare (shader_out ) (array int 1) gl_SampleMask)
>>
>> what's the utility of using size 0?
>> I'll take care of rest of your comments in this patch.
>
> Using size 0 is like writing
>
> int gl_SampleMask[]; // unsized
>
> in the shader. Later during compilation, usually in linking, unsized
> arrays become sized. Somewhere between generating the built-in variable
> and printing the IR a size is established for it.
Right, but gl_SampleMask is not an unsized array. It's statically sized
based on your implementation's maximum supported number of color samples
(ceil(samples/32)), and this is totally known at compile time...
--Ken
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