[CaptureTracking] Volatile operations capture their memory location

The memory location that corresponds to a volatile operation is very
special.  They are observed by the machine in ways which we cannot
reason about.

Differential Revision: http://reviews.llvm.org/D20555

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270879 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed