Initial implementation of 'fence' instruction, the new C++0x-style replacement for llvm.memory.barrier.

This is just a LangRef entry and reading/writing/memory representation; optimizer+codegen support coming soon.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136009 91177308-0d34-0410-b5e6-96231b3b80d8
18 files changed