[avr-gcc-list] loop deleted using optimization

[alee]

Why does avr-gcc delete my empty "for" loops if I compile with 
optimization on?
I am able to preserve the loop if I add a NOP in the loop but that will 
eat up one clock cycle.  Is there a way to preserve the empty loops 
without adding any NOP clock cycles?  Is this a bug?  Below is a test C 
code and the avr-gcc generated asm:

///////////*  C  code /////////////*/
int main(void)
{   int counton, countoff;
   int tempcount;
  do
  {
       counton = 27; countoff=1700;  //should div by 23
       for(tempcount = 0; tempcount < counton; tempcount++)
       { ;
       }
       for(tempcount = 0; tempcount < countoff; tempcount++)
       {;
       }
  }
  while(1);
  return 0;
}

///////* ASM code /////////////*/
main:
/* prologue: frame size=0 */
       ldi r28,lo8(__stack - 0)
       ldi r29,hi8(__stack - 0)
       out __SP_H__,r29
       out __SP_L__,r28
/* prologue end (size=4) */
       ldi r24,lo8(0)
       ldi r25,hi8(0)
       rjmp .L12
.L4:
       adiw r24,1
.L12:
       cpi r24,27
       cpc r25,__zero_reg__
       brlt .L4
       ldi r24,lo8(0)
       ldi r25,hi8(0)
       rjmp .L12
/* epilogue: frame size=0 */