At the moment, proveNoWrapViaConstantRanges is only used when creating
SCEV[Zero,Sign]ExtendExprs. We can get significant improvements by
strengthening flags after creating the AddRec.
I'll also share a follow-up patch that removes the code to strengthen
flags when creating SCEV[Zero,Sign]ExtendExprs. Modifying AddRecs while
creating those can lead to surprising changes.
Compile-time looks neutral: