[llvm] [DAG] computeKnownFPClass - add ISD::SINT_TO_FP/UINT_TO_FP handling (PR #190539)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

You're on the right track, but I'd expect it to handle as many similar cases to valuetracking's implementation as possible - in particular its never negzero/subnormal and never infinity if the integer src bitwidth is small enough.

https://github.com/llvm/llvm-project/pull/190539