GLSL to Slang Questions

[jkwak-work]

Creating an issue from a discussion.

Discussed in https://github.com/shader-slang/slang/discussions/4454

^{Originally posted by **LouChiSoft** June 22, 2024} Hi, I'm converting some GLSL code to Slang (and them compiling it back out to GLSL for comparison). I have a very basic GLSL shader that looks like this: ```glsl #[compute] #version 450 layout(std430, binding = 0) buffer buffer_t { float _data[]; } data; layout(local_size_x_id = 0, local_size_y_id = 1, local_size_z = 1) in; void main() { uint index = gl_GlobalInvocationID.x + (gl_WorkGroupSize.x * gl_GlobalInvocationID.y); data._data[index] = data._data[index] * 5; return; } ``` Most of the conversion is straight forward but I have ran into two issues so far that I can't seem to find an answer on: - Issue 1 is how do you define a specialisation constant in Slang? As you can see in the example above I use specialisation constants to decide the size of the workgroup at runtime, but so far I have only been able to get compile time sizes working in Slang. - Issue 2 is that `WorkGroupSize()` doesn't appear to work. Whenever I try to use it I get `unimplemented feature in Slang compiler`. I assume that means that it doesn't work for the GLSL backend, is there an alternative? Slang version for reference: ```C# RWStructuredBuffer data; [shader("compute")] [numthreads(5, 2, 1)] void computeMain(uint3 threadId: SV_DispatchThreadID) { int3 size = WorkgroupSize(); uint index = threadId.x + (size.x * threadId.y); data[index] = data[index] * 5; } ```

[ArielG-NV]

Note: problem is that WorkgroupSize(); inst is not deleted properly, causes the kIROp to make it to emitting IR stage (causes compile to fail since unimplemented KIROp)