Re: [avr-gcc-list] error with optimized boolean logic in gcc

[Georg-Johann Lay]

Sean D'Epagnier wrote:
> On Fri, Nov 25, 2011 at 11:18:17AM +0100, Georg-Johann Lay wrote:
>>> In avr.md I changed:
>>>    return "sbi %i0,%2";
>>> to
>>>    return "sbi %i0-0x20,%2";
>>>
>>> It fixed the problem.  I think this needs to be done all over the place
>> This is an incorrect fix, the problem must be somewhere else.
>>
> 
> Indeed, I didn't like it much, but it helped me understand the problem.
> 
>> %i shall subtract avr_current_arch->sfr_offset which is 0x20 for all
>> architectures.  The reason to use %i and not %m is to avoid magic
>> numbers 0x20 all over the place, see top of following changeset and
>> %i implementation in avr.c:print_operand()
>>
>> http://gcc.gnu.org/viewcvs?view=revision&revision=181552
>>
>> +      else if (code == 'i')
>> +        {
>> +          if (!io_address_operand (addr, GET_MODE (x)))
>> +            fatal_insn ("bad address, not an I/O address:", addr);
>> +
>> +          switch (INTVAL (addr))
>> +            {
>> +            case RAMPZ_ADDR: fprintf (file, "__RAMPZ__"); break;
>> +            case SREG_ADDR: fprintf (file, "__SREG__"); break;
>> +            case SP_ADDR:   fprintf (file, "__SP_L__"); break;
>> +            case SP_ADDR+1: fprintf (file, "__SP_H__"); break;
>> +
>> +            default:
>> +              fprintf (file, HOST_WIDE_INT_PRINT_HEX,
>> +                       UINTVAL (addr) - avr_current_arch->sfr_offset);
>> +              break;
>> +            }
>> +        }
>>
> 
> This makes a lot more sense now, but the above code is never reached.
> If you go a bit higher up in the function you will see:
> 
>   else if (GET_CODE (x) == CONST_INT)
> ->  fprintf (file, HOST_WIDE_INT_PRINT_DEC, INTVAL (x) + abcd);
>   else if (GET_CODE (x) == MEM)
>     {
>       ...
>       bit of code from above
>       ...
>     }
> 
> code is indeed 'i', but GET_CODE(x) is CONST_INT not MEM, so the conversion
> never takes place.
> 
> We could of course perform the conversion in both places, but I don't
> really like that either.  Maybe perform the subraction earlier as for abcd?
> 
> Sean

Please f'up

http://gcc.gnu.org/ml/gcc-patches/2011-11/msg02400.html

Johann