[clang] [ARM] enable FENV_ACCESS pragma support for hard-float targets (PR #137101)

[David Green via cfe-commits]

davemgreen wrote:

The MVE side is now all committed, making sure that we don't scalarize the intrinsics. There was a question about whether we should be using target specific intrinsics for it, but I believe we need to as we can't really convert the constrained intrinsics into mve instructions. I think we need something similar for Neon, at least to stop the intrinsics from scalarizing. I've not looked into how many different types of nodes that would be.

A few other things I have noticed:
 - ldexp does not seem to work for fp16 vectors https://godbolt.org/z/MW3jqx797. It should be able to scalarize.
 - There are a number of problems with the various min/max's, some that are present for both standard nodes and strictfp.
 - On systems without fullfp16, fp16 nodes do not lower at the moment https://godbolt.org/z/3qh3fbWjG. (For systems without fp64 we do manage to produce libcalls).

https://github.com/llvm/llvm-project/pull/137101