Missed optimization in m68k

[law@redhat.com]

In message <200206141923.g5EJNeK22444@hyper.wm.sps.mot.com>, Peter Barada write
s:
 > 
 > I'm compiling the small snippet:
 > 
 > char *copy(const char *src, char *dst)
 > {
 >   char *dst0 = dst;
 >   while (*dst++ = *src++)
 >     ;
 >   return dst0;
 > }
 > 
 > And when compiled with 3.0.4 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
 > 
 > 
 > The problem is that the tst.b is not necessary since the move.b
 > updated the condition codes as part of the move.  How can I best
 > convince gcc that it should generate the follwing instead:
 > 
 > copy:
 > 	move.l 4(%sp),%a1
 > 	move.l 8(%sp),%a0
 > 	move.l %a0,%d0
 > .L2:
 > 	move.b (%a1)+,(%a0)+
 > 	jbne .L2
 > 	rts
 > 
 > Thanx...
I believe you'll be hacking in NOTICE_UPDATE_CC.

jeff