[LoopUnrollAnalyzer] Handle out of bounds accesses in visitLoad

While we handed loads past the end of an array, we didn't handle loads
_before_ the array.

This fixes PR28062.

N.B. While the bug in the code is obvious, I am struggling to craft a
test case which is reasonable in size.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276510 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed