As a follow-up to r328480, this updates the logic for the decreasing
safety checks in a similar manner:
- CanBeMax is replaced by CannotBeMaxInLoop which queries
isLoopEntryGuardedByCond on the maximum value.
- SumCanReachMin is replaced by isSafeDecreasingBound which includes
some logic from parseLoopStructure and, again, has been updated to
use isLoopEntryGuardedByCond on the given bounds.
Differential Revision: https://reviews.llvm.org/D44776
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328613 91177308-0d34-0410-b5e6-96231b3b80d8
0ba1cd85f0