[llvm] [ConstantFolding] Fold expm1/expm1f with constant arguments (PR #196717)

[Iris Shi via llvm-commits]

https://github.com/el-ev requested changes to this pull request.

This needs tests. Please add a LIT test for your changes under `llvm/test/Transforms/InstSimplify/ConstProp` and pre-commit it.

Please refer to https://llvm.org/docs/TestingGuide.html

https://github.com/llvm/llvm-project/pull/196717