[InstCombine] Merge duplicate functionality between InstCombine and ValueTracking
Summary:
Merge overflow computation for signed add,
appearing both in InstCombine and ValueTracking.
As part of the merge,
cleanup the interface for overflow checks in InstCombine.
Patch by Yoav Ben-Shalom.
Reviewers: craig.topper, majnemer
Reviewed By: craig.topper
Subscribers: takuto.ikuta, llvm-commits
Differential Revision: https://reviews.llvm.org/D32946
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303029
91177308-0d34-0410-b5e6-
96231b3b80d8