[llvm] ValueTracking: teach implied-cond about samesign (PR #116614)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

> isImpliedCondition benefits little from the icmp samesign feature: the only routine that can use this information is isImpliedCondICmps when it is matching against signed predicates, since icmp samesign is already canonicalized with an unsigned predicate. Add this support.

Hm, why do other parts of isImpliedCond not benefit? I'd expect it to be useful at least for the isImpliedCondMatchingOperands and isImpliedCondOperands logic, possibly also isImpliedCondCommonOperandWithCR.

The code you're modifying here is a very special case -- it's probably exactly the one part of this code where I wouldn't bother with samesign support :)

https://github.com/llvm/llvm-project/pull/116614