Add an assertion to make PR7542 fail consistently.

LiveInterval::overlapsFrom dereferences end() if it is called on an empty
interval.

It would be reasonable to just return false - an empty interval doesn't overlap
anything, but I want to know who is doing it first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108264 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed