[SCEV] Reapply 'Exploit A < B => (A+K) < (B+K) when possible'
Summary:
This change teaches SCEV's `isImpliedCond` two new identities:
A u< B u< -C => (A + C) u< (B + C)
A s< B s< INT_MIN - C => (A + C) s< (B + C)
While these are useful on their own, they're really intended to support
D12950.
The original checkin, r248606 had to be backed out due to an issue with
a ObjCXX unit test. That issue is now fixed, so re-landing.
Reviewers: atrick, reames, majnemer, nlewycky, hfinkel
Subscribers: aadg, sanjoy, llvm-commits
Differential Revision: http://reviews.llvm.org/D12948
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248637 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed