Add lock prefix support to x86.  Also add the instructions necessary for the atomic ops.  They are still marked pseudo, since I cannot figure out what format to use, but they are the correct opcode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47795 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed