Summary:
Previously it only avoided optimizing signed comparisons to 0.
Sometimes the DAGCombiner will optimize the unsigned comparisons
to 0 before it gets to the peephole pass, but sometimes it doesn't.
Fix for PR22373.
Test Plan: test/CodeGen/ARM/sub-cmp-peephole.ll
Reviewers: jfb, manmanren
Subscribers: aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D7274
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227809 91177308-0d34-0410-b5e6-96231b3b80d8
1a63641597