Fix a couple bugs in the way we handle array indexes in array bounds checking.  Specifically, make sure we don't ignore explicit casts in indexes, and make sure we use unsigned extension/comparisons on indexes.  Fixes <rdar://problem/10916006>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151569 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed