Added documentation to getMemsetStores.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190866 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused code, which had been commented out.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190869 91177308-0d34-0410-b5e6-96231b3b80d8