[libclc] [libclc] Add (fast) normalize to CLC; add half overloads (PR #139759)

[Fraser Cormack via cfe-commits]

frasercrmck wrote:

> > The OpenCL-CTS doesn't actually test the geometrics builtins with that option - that's just for bruteforce.
> 
> Sounds like a bug
> 
> > It passes on an OpenCL implementation which advertises support for single-precision denormals, yes.
> 
> Ideally would check it works with denormal flushing forced on, that's the main risk I can see. If I were to stare at this long enough I could probably guess at where the constant was derived from

Yeah, it sounds simpler just to keep the old constants. I've done that now, and there's no codegen changes. I'll update the PR description.

https://github.com/llvm/llvm-project/pull/139759