Yingwei Zheng aad3a1630e [ValueTracking] Respect samesign flag in isKnownInversion (#112390) ...

In https://github.com/llvm/llvm-project/pull/93591 we introduced
`isKnownInversion` and assumes `X` is poison implies `Y` is poison
because they share common operands. But after introducing `samesign`
this assumption no longer hold if `X` is an icmp has `samesign` flag.

Alive2 link: https://alive2.llvm.org/ce/z/rj3EwQ (Please run it locally
with this patch and https://github.com/AliveToolkit/alive2/pull/1098).

This approach is the most conservative way in my mind to address this
problem. If `X` has `samesign` flag, it will check if `Y` also has this
flag and make sure constant RHS operands have the same sign.

Fixes https://github.com/llvm/llvm-project/issues/112350.

2024-10-17 00:27:21 +08:00

370 KiB

Raw Blame History

View Raw