On Tue, 30 May 2017, Alexander Monakov wrote: > I believe implementing ldaxp/stlxp in the backend and using them to expand > 128-bit CAS (and other 128-bit atomics, except for atomic load) ... Sorry, that was unclear. To clarify, ldaxp/stlxp, if implemented, could be used to implement 128-bit __sync built-ins, if AArch64 were to follow the approach currently taken on x86. However, they could not be used to implement 128-bit __atomic built-ins, like 128-bit cas is today not used on x86 for that purpose either, because __atomic builtins provide a 'load' operation, and an implementation using ldaxp-stlxp to implement an atomic load would fault on read-only memory. Alexander
