ref: 1ce4437f4fb4cd3c541f9dd7d1fabffb04eb317b
dir: /syscall-osx.s/
.globl _std$syscall
_std$syscall:
popq %rcx /* return address */
popq %rax /* call num */
pushq %rcx
syscall
pushq %rcx /* put the return address back */
ret