Add GroupSharedLimit attribute support for Mesh, Amp and Node shaders

[JoeCitizen]

• Adds support for the GroupSharedLimit feature for Mesh, Amplification and Node shaders.
• Tests for each of those shader types

[tex3d]

With minor suggested changes from earlier resolved comment, tests could easily check some more interesting edge cases that I've pointed out. As it stands, I'm not sure the update truly addressed the resolved comment from earlier.

[tex3d]

Diagnostics need overhaul, but I've provided a suggested implementation.

[V-FEXrt]

Generally LGTM but the more I sat with it, the more I think we need to do something about the -1 magic. Happy to leave it up to you on exactly what to do but it should be named in some manner

[V-FEXrt]

I won't block on this, but I feel that using magic numbers to encode information is generally a bad idea.

If you want to encode so notion of "not-set" using something like std::optional is more appropriate

[V-FEXrt]

I think I've now deduced that -1 -> Use max size? That seems a bit counterintuitive to me but probably a named constant is enough to clear that up

[JoeCitizen]

I generally I agree, I was following the convention that appears to be set in the line above where LocalRootArgumentsTableIndex is initialised to -1

[tex3d]

Generally, we either need a special value for "unset" or an additional flag somewhere. We can add a define for this to make the code semantically better, or we can add another field/flag. Adding a flag won't change or require more metadata because this should be preserved by whether the extended metadata tag is present at all, not by any special value. We could even add accessors (get/set/isSet/unset) to keep the flag in sync. Though just adding a special defined value for "unset" seems like the simplest solution.

[tex3d]

@V-FEXrt: -1 doesn't mean "max size", it means the default isn't overridden for the shader entry. The max size used when not overridden by the shader is a long-standing default value from defines (32k for compute-like shaders except mesh shader which is 28k). The shader can set a larger size than that default, and if it uses more than the default, the runtime will check device capability to make sure the shader can run.

[tex3d]

Oh yeah, given this definition, I think std::optional would work fine instead of an explicit flag and extra accessors defined in this class.

[V-FEXrt]

Makes sense, to be clear, I'm not specifically set on std:optional, I would be happy with a simple #define, we just have a lot of -1s floating around in the PR. even something like GS_USE_DEFAULT_SIZE would make the later code a lot easier to read

[V-FEXrt]

More important than using std::optional, this should be named in some manner[1]. What does it mean that grouSharedLimitBytes is -1?

[1]: my personal preference would be a tiny helper function but I'm flexible. Another option is defining as constant for -1 with a name that gives enough context to the meaning

[github-actions]

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