[llvm] [DAG] Early exit for flags in canCreateUndefOrPoison [nfc] (PR #89834)

[Philip Reames via llvm-commits]

preames wrote:

@bjope I believe in your example the flags could be trivially re-inferred after any transform which drops them.  (Well, or at least the major transform this analysis drives which is freeze hoisting/elimination.)  As such, I'm not sure how useful strengthening the analysis would be.  

However, at a macro level, I think you're raising a question which is well beyond the scope of this review.  If in the future, we decide to handle your case differently, we would of course change the code.  Going with a particular style now does not prevent us choosing a different style at a later point if the problem being solved has changed.  

https://github.com/llvm/llvm-project/pull/89834