Useful for code reuse for Metal shader build both for eager mode and MPSInductor, but it requires one to implement `_cpp_embed_headers` tool that, as name suggests, would preprocess and embeds the for shader to be used in dynamic compilation.
Test using:
- `TestMetalLibrary.test_metal_include`
- Moving `i0`/`i1` implementation to `c10/util/metal_special_math.h` and call it from `SpecialOps.metal` shader, which now looks much more compact:
```metal
template <typename T, typename Tout = T>
void kernel
i0(constant T* input,
device Tout* output,
uint index [[thread_position_in_grid]]) {
output[index] = c10::i0(static_cast<Tout>(input[index]));
}
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/145087
Approved by: https://github.com/dcci
ghstack dependencies: #145023
