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

[Georg-Johann Lay]

Georg-Johann Lay wrote:
> 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

It's upstream in 181722:

http://gcc.gnu.org/viewcvs?view=revision&revision=181722

Johann