Support thread group size reflection for compute shaders

[domme]

There doesn't seem to be a way to retrieve the local group-thread count for compute shaders yet. Are there any plans of adding support for that?

[shangjiaxuan]

This can currently be done through SpvReflectEntryPoint::local_size. It currently does not support numbers with specialization constants. That is being implemented through pr #154

[MOARdV]

I've been trying to get the local size info, and it does not appear to work. I have a GLSL compute shader with

#version 460 core

layout(local_size_x = 64, local_size_y = 1, local_size_z = 1) in;
(snip)

and if I reflect "main", SpvReflectionEntryPoint::local_size reports (0, 0, 0).

The mesh shader I have likewise reports a (0, 0, 0) size, despite it being configured as (1, 1, 1).

I have also tried using local_size_[x|y|z]_id as well.

These results are from the SPIRV-Reflect bundled with the Vulkan Windows SDK 1.3.246.1

[shangjiaxuan]

@MOARdV Spirv-Reflect what's the output of spirv-dis? Does it contain an instruction of OpExecutionModeLocalSize?

[MOARdV]

@shangjiaxuan There is no OpExecutionModeLocalSize.

There is OpExecutionModeId %main LocalSizeId %uint_64 %uint_1 %uint_1

This is the only place in the file that contains the string "Local".

[shangjiaxuan]

@MOARdV looks like a specialization constant support problem. My pr #154 adds support, but is a long way from being merged.