ref: 515b8e89c1a6c0859eaefbf7835a4e6497a57e0b
dir: /libstd/syscall+freebsd-x64.s/
.globl sys$syscall sys$syscall: /* hack: We load 6 args regardless of how many we actually have. This may load junk values, but if the syscall doesn't use them, it's going to be harmless. */ movq %rdi,%rax movq %rsi,%rdi movq %rdx,%rsi movq %rcx,%rdx movq %r8,%r10 movq %r9,%r8 movq 8(%rsp),%r9 syscall ret