[Piglit] [PATCH] shader_image: fix max images if fragment shader has limited outputs.

[Dave Airlie]

On 1 March 2018 at 04:08, Francisco Jerez <currojerez at riseup.net> wrote:
> Dave Airlie <airlied at gmail.com> writes:
>
>> From: Dave Airlie <airlied at redhat.com>
>>
>> This drops one from the max images as the fragment shader needs
>> one output for outputing the results
>>
>> Signed-off-by: Dave Airlie <airlied at redhat.com>
>> ---
>>  tests/spec/arb_shader_image_load_store/image.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/tests/spec/arb_shader_image_load_store/image.c b/tests/spec/arb_shader_image_load_store/image.c
>> index e664d3cc4..1bfaebfdb 100644
>> --- a/tests/spec/arb_shader_image_load_store/image.c
>> +++ b/tests/spec/arb_shader_image_load_store/image.c
>> @@ -670,11 +670,14 @@ num_reserved_images(GLbitfield stages)
>>  unsigned
>>  image_stage_max_images(const struct image_stage_info *stage)
>>  {
>> -        int n = 0;
>> +        int n = 0, n2 = 0;
>>
>>          switch (stage->stage) {
>>          case GL_FRAGMENT_SHADER:
>>                  glGetIntegerv(GL_MAX_FRAGMENT_IMAGE_UNIFORMS, &n);
>> +                glGetIntegerv(GL_MAX_COMBINED_SHADER_OUTPUT_RESOURCES, &n2);
>> +             if (n == n2)
>> +                     n--;
>
> I don't think this is guaranteed to fix the problem where there is one.
> GL_MAX_COMBINED_SHADER_OUTPUT_RESOURCES imposes a limit on the number of
> active image units in the whole pipeline, and you can reach it whether
> GL_MAX_FRAGMENT_IMAGE_UNIFORMS is equal, lower or greater than
> GL_MAX_COMBINED_SHADER_OUTPUT_RESOURCES.  You probably need to fix the
> test case instead to require a lower number of image units.

In practice the number of drivers that set
GL_MAX_COMBINED_SHADER_OUTPUT_RESOURCES
to a lower value is evergreen gpus, and they don't support image units
anywhere else in the pipeline.

I'm not sure we'll see any other gpu where it's very different.

Dave.