This is a tracking bug for a task. It's likely non-controversial; it just needs to be done.

The spec currently has no notion of a standard library. We need to find the intersection of library functions from HLSL, MSL, and SPIR-V, and specify them in the spec.

Regarding the polyfillable functions: We also need to make a determination about how much polyfilling the implementation is required to do, vs how much polyfilling the author is required to do.