  We develop a new intermediate weak memory model, IMM, as a way of
modularizing the proofs of correctness of compilation from concurrent
programming languages with weak memory consistency semantics to mainstream
multi-core architectures, such as POWER and ARM. We use IMM to prove the
correctness of compilation from the promising semantics of Kang et al. to POWER
(thereby correcting and improving their result) and ARMv7, as well as to the
recently revised ARMv8 model. Our results are mechanized in Coq, and to the
best of our knowledge, these are the first machine-verified compilation
correctness results for models that are weaker than x86-TSO.
