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.

llvm-svn: 136009
diff --git a/llvm/lib/VMCore/Instruction.cpp b/llvm/lib/VMCore/Instruction.cpp
index 4627e71..4597b57 100644
--- a/llvm/lib/VMCore/Instruction.cpp
+++ b/llvm/lib/VMCore/Instruction.cpp
@@ -127,6 +127,7 @@
   case Alloca:        return "alloca";
   case Load:          return "load";
   case Store:         return "store";
+  case Fence:         return "fence";
   case GetElementPtr: return "getelementptr";
 
   // Convert instructions...