In commit2b582440c1, we canonicalize the isInf/isNanOrInf idiom into fabs+fcmp for better analysis/codegen (See also the discussion in https://github.com/llvm/llvm-project/pull/76338). This patch reverses the fabs+fcmp to `is.fpclass`. If the `is.fpclass` is not supported by the target, it will be expanded by TLI. Fixes the regression introduced by2b582440c1and https://github.com/llvm/llvm-project/pull/80414#issuecomment-1936374206.