Provides basic implementations of the barrier instruction introduced
within ARMv7. Currently these simply mirror the behavior of the AArch64
equivalents.
ARM's Architecture Specification Language doesn't distinguish between floats and integers
as much as we do. This makes some things difficult to implement. Since our register
allocator is now capable of allocating values to XMMs and GPRs as necessary, the
Transfer IR instructions are no longer necessary as they used to be and they can be
removed.