[llvm] [RFC][SPIR-V] Add intrinsics to convert to/from ap.float (PR #164252)

[Nikita Popov via llvm-commits]

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nikic wrote:

I'd add a note to both intrinsics that the supported conversions are target dependent. (These aren't going to get generic legalization support, right?)

https://github.com/llvm/llvm-project/pull/164252