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

[Eric Xu via cfe-commits]

ericxu233 wrote:

> > > @phoebewang Are you OK with this? An alternative is we just allow exact rounding (which is what we'll end up doing for the SSE2 style conversions like CVTPD2DQ).
> > 
> > 
> > Can we check for strictfp mode? I think we can assume `NearestTiesToEven` in non strictfp mode.
> 
> @ericxu233 ping?

I am unsure of with means? Could you elaborate on this a little bit? I thought the rounding mode used was from the instructions. Do you mean that in non-strictfp mode and in MXCSR, I assume "NearestTiesToEven"?

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