usr/src/cmd/lisp/mcount.s

        .asciz  "@(#)mcount.s   34.1    10/3/80"
# count subroutine called during profiling

.globl  mcount
.globl _mcount
.comm   _countbase,4

_mcount:
mcount:
        movl    (r0),r1
        beql    init
incr:
        incl    (r1)
return:
        rsb
init:
        movl    _countbase,r1
        beql    return
        addl2   $8,_countbase
        movl    (sp),(r1)+
        movl    r1,(r0)
        brb     incr