Re: [avr-gcc-list] [Bug] Initialization for _delay_loop_2 Optimized Out

[Dave Hansen]

> As "Dave Hansen" <address@hidden> wrote:
[...]
> >Which, again, is the whole point of the bug report.  I haven't tried it 
> (I
> >don't have the time right now), but I suspect the following:
> >
> >   #include <avr/delay.h>
> >   int main (void)
> >   {
> >      while(1)
> >         _delay_loop_2(3);
> >
> >      return 0;
> >   }
> >
> >Would generate incorrect code.
>
> For me, it works, and generates the following code:
>
> ..
> .L6:
>         ldi r24,lo8(3)
>         ldi r25,hi8(3)
> /* #APP */
>         1: sbiw r24,1
>         brne 1b
> /* #NOAPP */
>         rjmp .L6

Interesting.  Here are the last few lines of the .LSS file that gets 
generated when I build the code:

0000008e <main>:
  #include <avr/delay.h>
  int main (void)
  {
 8e:   cf e5           ldi     r28, 0x5F       ; 95
 90:   d8 e0           ldi     r29, 0x08       ; 8
 92:   de bf           out     0x3e, r29       ; 62
 94:   cd bf           out     0x3d, r28       ; 61
/* 16-bit count, 4 cycles/loop */
static inline void
_delay_loop_2(unsigned int __count)
{
       asm volatile (
 96:   01 97           sbiw    r24, 0x01       ; 1
 98:   f1 f7           brne    .-4             ; 0x96
 9a:   fd cf           rjmp    .-6             ; 0x96

Notice the brne and the rjmp target the same location.  So it doesn't work 
for me.  What version are you using?

Regards,
  -=Dave

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