1. if the underlying pointer passed in can be resolved
to any argument or alloca, then we don't need to scan.
Previously we would only avoid the scan if the alloca
or byval was actually considered dead.
2. The dead store processing code is itself completely
dead and didn't handle volatile stores right anyway,
so delete it. This allows simplifying the interface
to RemoveAccessedObjects.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120467 91177308-0d34-0410-b5e6-96231b3b80d8