[Piglit] [PATCH] glsl-fs-main-return-conditional: Test for using return in main

[Roland Scheidegger]

Am 23.03.2013 01:41, schrieb Ian Romanick:
> On 03/22/2013 03:28 PM, sroland at vmware.com wrote:
>> From: Roland Scheidegger <sroland at vmware.com>
>>
>> Similar to glsl-fs-main-return (and glsl-vs-main-return), this is testing
>> using return in main. Contrary to the these other tests, this hits both
>> the cases where the return path is and is NOT taken (the gallivm code
>> got it wrong and always did an early exit which got unnoticed by the
>> existing tests, see https://bugs.freedesktop.org/show_bug.cgi?id=62357).
>> It also needs glsl 1.30 (even though this is not specific to what's
>> tested
>> here).
> 
> Are there any drivers in Mesa that don't expose GLSL 1.30 but would
> benefit from this test?
I don't think so but I'm not sure.

> 
>> ---
>>   .../glsl-fs-main-return-conditional.shader_test    |   34
>> ++++++++++++++++++++
>>   1 file changed, 34 insertions(+)
>>   create mode 100644
>> tests/shaders/glsl-fs-main-return-conditional.shader_test
>>
>> diff --git a/tests/shaders/glsl-fs-main-return-conditional.shader_test
>> b/tests/shaders/glsl-fs-main-return-conditional.shader_test
>> new file mode 100644
>> index 0000000..124a4cd
>> --- /dev/null
>> +++ b/tests/shaders/glsl-fs-main-return-conditional.shader_test
>> @@ -0,0 +1,34 @@
>> +[require]
>> +GLSL >= 1.30
>> +
>> +[vertex shader]
>> +#version 130
>> +void main()
>> +{
>> +    gl_Position = gl_Vertex;
>> +}
>> +
>> +[fragment shader]
>> +#version 130
>> +uniform vec4 v;
> 
> This could just be
> 
> const vec4 v = vec4(0., 1., 0., 1.);
> 
> and delete the uniform setting in the [test] section.
Yeah I guess this was a uniform originally so the compiler wouldn't just
get rid of the conditional altogether but since the condition no longer
depends on it this is unnecessary.

> 
>> +
>> +void main()
>> +{
>> +    uint posintx = uint(gl_FragCoord.x);
>> +    uint one = uint(1);
>> +    gl_FragColor = v;
>> +    if ((posintx & one) == one) {
>> +        return;  // return for every second pixel
>> +    }
>> +    gl_FragColor = vec4(1.0) - v;
>> +}
> 
> It seems like this could be done as:
> 
> void main()
> {
>     floor x = floor(gl_FragCoord.x - 0.5);
> 
>     gl_FragCoord = v;
>     if (mod(x, 2.0) > epsilon)
>         return;
> 
>     gl_FragColor = vec4(1.0) - v;
> }
Sounds like a good idea, I forgot about the mod() which gets rid of glsl
1.30 requirement. In fact the floor is unnecessary too can simplify this
more. I'll send out another version...

Roland