[clang] [X86][Clang] Support constexpr evaluation of cvtpd2ps intrinsics (PR #169980)

[Hamza Hassanain via cfe-commits]

HamzaHassanain wrote:

Hello. Am I supposed to merge my branch with the main branch (my last 3 commits) or this is not right , and I should redo the PR ? 

https://github.com/llvm/llvm-project/pull/169980