In the original design of the analyzer, it was assumed that a BlockEntrance
doesn't create a new binding on the Store, but this assumption isn't true when
'widen-loops' is set to true. Fix this by finding an appropriate location
BlockEntrace program points.
Patch by Henry Wong!
Differential Revision: https://reviews.llvm.org/D37187
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@319333 91177308-0d34-0410-b5e6-96231b3b80d8