SLPVectorizer: Don't vectorize volatile memory operations

radar://15231682

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192799 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Add support for NEON scalar signed saturating accumulated of unsigned
value and unsigned saturating accumulate of signed value instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192800 91177308-0d34-0410-b5e6-96231b3b80d8