[llvm] [InstSimplify] Defer to ConstantFold in simplifyInstrinsic (PR #205061)

[Nikita Popov via llvm-commits]

nikic wrote:

> The patch includes a ConstantFolding fix for strictfp.

Please explain in more detail, I do not understand this change. What tests were previously failing / how?

https://github.com/llvm/llvm-project/pull/205061