Patch to check for integer overflow. It has been
commented on and approved by Richard Smith.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173377 91177308-0d34-0410-b5e6-96231b3b80d8
removed duplicated comment.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173378 91177308-0d34-0410-b5e6-96231b3b80d8
FileCheck-ify some debug info scope related tests.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173379 91177308-0d34-0410-b5e6-96231b3b80d8