On 05/09/2016 12:24 PM, Tobias Klausmann wrote:
>
> On 09.05.2016 20:41, Ian Romanick wrote:
>
>> snip
>>> + /* From the ARB_cull_distance spec:
>>> + *
>>> + * It is a compile-time or link-time error for the set of
>>> shaders forming
>>> + * a program to have the sum of the sizes of the
>>> gl_ClipDistance and
>>> + * gl_CullDistance arrays to be larger than
>>> + * gl_MaxCombinedClipAndCullDistances.
>>> + */
>>> + if ((*clip_distance_array_size + *cull_distance_array_size) >
>>> + ctx->Const.MaxClipPlanes) {
>>> + linker_error(prog, "%s shader: the combined size of "
>>> + "'gl_ClipDistance' and 'gl_CullDistance' size
>>> cannot "
>>> + "be larger than "
>>> + "gl_MaxCombinedClipAndCullDistances (%u)",
>>> + _mesa_shader_stage_to_string(shader->Stage),
>>> + ctx->Const.MaxClipPlanes);
>>> + }
>> I think this is the wrong check for this limitation in the spec. This
>> will only catch cases where the usages within a stage exceed the limit.
>> I *believe* (but it's not 100% clear from the quotation) that a vertex
>> shader that writes MaxClipPlanes elements to gl_ClipDisatnce and a
>> geometry shader that also writes MaxClipPlances to gl_CullDistance
>> should fail to link. If that is the case, then we need checks elsewhere
>> that use LastClipDistanceArraySize and LastCullDistanceArray size to
>> enforce the limits.
>
> I think you are right, but where would be the best place (stage) to
> check this? (You know the codebase way better)
Right after LastClipDistanceArraySize is set in link_shaders seems like
a good place. Maybe pull that code, the code added by this patch to set
LastCullDistanceArraySize, and the new validation code to a new
function. link_shaders is pretty long. :(
> Thanks,
> Tobias
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