missed optimization in m68k

[Peter Barada]

When I build the follwing snippet on my ColdFire v4e modified
version(even in m68k mode using -mc68020) I get:

char *copy(const char *src, char *dst)
{
  char *dst0 = dst;
  while (*dst++ = *src++)
    ;
  return dst0;
}


copy:
	move.l %a2,-(%sp)
	move.l 8(%sp),%a1
	move.l 12(%sp),%a0
	move.l %a0,%a2
.L2:
	move.b (%a1)+,(%a0)
	tst.b (%a0)+
	jbne .L2
	move.l %a2,%d0
	move.l (%sp)+,%a2
	rts


Whereas I build it got -mcfv4e (my own tweaked version) I get:

copy:
	move.l 4(%sp),%a1
	move.l 8(%sp),%a0
	move.l %a0,%d0
.L2:
	move.b (%a1)+,(%a0)
	tst.b (%a0)+
	jbne .L2
	rts

So I'm wondering where to check for the extra move of %a0 to %a2 came
from instead of moveing it to %d0.

Any ideas will be most appreciated.  TIA...

-- 
Peter Barada                                   Peter.Barada@motorola.com
Wizard                                         781-852-2768 (direct)
WaveMark Solutions(wholly owned by Motorola)   781-270-0193 (fax)