Re: [avr-gcc-list] Problems with avr-gcc vers 3.0

[johan.olin]

Hi,
I got the same result when compiling with
-O3 opt. level. (which I think is used in the gcctest makefiles)

But, when I inserted some dummy code into the loop 
it seems to work as exptected ....
OR,
If I declared the counter variable as 'volatile' it also
seemed OK ....

Empty loops seem to be quite a popular target
for the optimizer .......

BR : Jussi

Maurizio Ferraris <address@hidden> wrote:

> Hi,
> I just switched to avr-gcc version 3.0 and successfully recompiled all my 
> old code.
> I even had a small reduction in code size.
> The problem is that the code is not working anymore.
> Looking around and trying to figure what happened, I came across this 
piece 
> of code.
> The delay routine is simply an empty loop from 0 to 4999. The 
> implementation is something that I don't understand and I feel that it 
is 
> wrong.
> The counter seems to be initialized at 4999 and not at zero (ok, since it 
> is not used inside the loop, it doesn't really matters), and it is 
> decremented toward zero, but not by one, but by 625.
> I used the packed installation found on avrfreaks for win32, and using 
the 
> makefiles found in the gcctest.zip (I didn't dare change any switches ... 
I 
> only added my files and include directories).
> Is there something I must know?
> 
>   102:../Common/Util.c **** void delay(void)
>   103:../Common/Util.c **** {
>   104:../Common/Util.c ****   int counter;
>   105:../Common/Util.c ****
>   106:../Common/Util.c ****   for(counter = 0; counter < 5000; 
counter++)
>   347 0104 87E8                  ldi r24,lo8(4999)
>   348 0106 93E1                  ldi r25,hi8(4999)
>   349                    .L35:
>   350 0108 8157                  subi r24,lo8(-(-625))
>   351 010a 9240                  sbci r25,hi8(-(-625))
>   352 010c EAF7                  brpl .L35
>   355 010e 0895                  ret
>   107:../Common/Util.c ****     ;
>   108:../Common/Util.c **** }
> 
> Thanks in advance.
> Mau.
> 
> 
_____________________________________________________________
> Maurizio Ferraris                mailto:address@hidden
> Via Borgonuovo 27                mailto:address@hidden
> 10040 GIVOLETTO TO ITALY         http://www.studioferraris.it
> 
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