Yes, it includes a runtime JIT component for apps that happen to dynamically generate x86-64, but in all other cases the binary is AOT translated. It does this

Yes, it includes a runtime JIT component for apps that happen to dynamically generate x86-64, but in all other cases the binary is AOT translated. It does this by inserting (during the AOT translation) function calls to a linked in, in-process translation function whenever it sees mmap’d or malloc’d regions being marked for execute and then jumped to - this data dependency on the jump instructions can be entirely determined from a static analysis of the executable, no violation of fundamental computing science principles required. So yeah, no real back and forth to the host platform.