where the step value is an induction variable from an outer loop, to
avoid trouble trying to re-expand such expressions. This effectively
hides such expressions from indvars and lsr, which prevents them
from getting into trouble.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111317 91177308-0d34-0410-b5e6-96231b3b80d8
