[clang] [X86][Clang] Allow constexpr evaluation of F16C CVTPS2PH intrinsics (PR #162295)

[Hanyang Xu via cfe-commits]

ericxu233 wrote:

@RKSimon 

> Do you think you can handle the avx512 vcvtps2ph*_mask builtins as well? It should main

Do I do all vcvtps2ph instructions? Some instructions are from AVX512_FP16 which have native support for half-precision floats. In order to support these instructions, I need to write new logic since the current logic only handles F16C-style half-precision floats which are short integers.

Maybe I can do the rest of the instructions, excluding the AVX512_FP16 instructions. And we can do the AVX512_FP16 instructions in the future?

https://github.com/llvm/llvm-project/pull/162295