indvars -disable-iv-rewrite: avoid multiple IVs in weird cases.

Putting back the helper that I removed on 7/1 to do this right.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134423 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed