This gets gas and llc -filetype=obj to agree on the order of prefixes.
For llvm-mc we need to fix the asm parser to know that it makes a difference
on which line the "lock" is in.
Part of pr23594.
llvm-svn: 238232
The logic for expanding atomics that aren't natively supported in
terms of cmpxchg loops is much simpler to express at the IR level. It
also allows the normal optimisations and CodeGen improvements to help
out with atomics, instead of using a limited set of possible
instructions..
rdar://problem/13496295
llvm-svn: 212119
Rafael Espindola