usr/src/lib/libc/gen/alloca.s

# @(#)alloca.s  4.1 (Berkeley) 12/21/80
# like alloc, but automatic
# automatic free in return

.globl  _alloca
_alloca:
        .word   0x0000
        subl2   4(ap),sp        # crude allocation
        movl    16(fp),r1       # pc
        movq    8(fp),ap        # new (old) ap and fp
        bicl2   $3,sp           # 4-byte align
        addl2   $7*4,sp         # reuse space of mscp
        movl    sp,r0           # return value
        jmp     (r1)            # funny return