[llvm] [InstCombine] Inverse is.fpclass mask operand, when profitable (PR #121378)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw requested changes to this pull request.

This case should be handled in CodeGen instead of InstCombine.
Fortunately, there is a helper function called `invertFPClassTestIfSimpler` to improve the codegen of `TLI.expandIS_FPCLASS`. You can adjust this function and `expandIS_FPCLASS` to make the codegen better on x86 and aarch64 :) https://godbolt.org/z/vh8476ae3


https://github.com/llvm/llvm-project/pull/121378