Mark intrinsics operating on the whole warp as IntrInaccessibleMemOnly

It's needed to model the fact that they do access data from other threads in a
warp and thus can't be CSE'd.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318173 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed