Re: double argument casting

[Jorge PEREZ <jorge dot perez at invia dot fr>]

Thanks for the feedback.

In that case your patch modification seems to work better since it seems
to remove the cast from the callee and does the sign extension on the
caller:

(gcc4.5.1 with your patch applied)

0001024c <somme>:
   1024c:    10 80 00 04     b  1025c <somme+0x10>
   10250:    82 10 20 00     clr  %g1
   10254:    82 00 60 01     inc  %g1
   10258:    91 3a 20 18     sra  %o0, 0x18, %o0
   1025c:    80 a0 40 09     cmp  %g1, %o1
   10260:    26 bf ff fd     bl,a   10254 <somme+0x8>
   10264:    91 2a 20 19     sll  %o0, 0x19, %o0
   10268:    90 02 00 09     add  %o0, %o1, %o0
   1026c:    91 2a 20 10     sll  %o0, 0x10, %o0
   10270:    81 c3 e0 08     retl 
   10274:    91 3a 20 10     sra  %o0, 0x10, %o0
 
  000102ac <main>:
   102ac:    9d e3 bf 98     save  %sp, -104, %sp
   102b0:    82 10 20 01     mov  1, %g1
   102b4:    c2 37 bf fc     sth  %g1, [ %fp + -4 ]
   102b8:    c2 2f bf ff     stb  %g1, [ %fp + -1 ]
   102bc:    c2 2f bf fe     stb  %g1, [ %fp + -2 ]
   102c0:    d0 0f bf ff     ldub  [ %fp + -1 ], %o0
   102c4:    d2 17 bf fc     lduh  [ %fp + -4 ], %o1
   102c8:    91 2a 20 18     sll  %o0, 0x18, %o0
   102cc:    93 2a 60 10     sll  %o1, 0x10, %o1
   102d0:    91 3a 20 18     sra  %o0, 0x18, %o0
   102d4:    7f ff ff de     call  1024c <somme>
   102d8:    93 3a 60 10     sra  %o1, 0x10, %o1
   102dc:    d0 37 bf fc     sth  %o0, [ %fp + -4 ]
   102e0:    d0 0f bf fe     ldub  [ %fp + -2 ], %o0
   102e4:    d2 17 bf fc     lduh  [ %fp + -4 ], %o1
   102e8:    91 2a 20 18     sll  %o0, 0x18, %o0
   102ec:    93 2a 60 10     sll  %o1, 0x10, %o1
   102f0:    91 3a 20 18     sra  %o0, 0x18, %o0
   102f4:    7f ff ff d6     call  1024c <somme>
...

isn't that right?


Thanks


Eric Botcazou wrote:
>> we modified the function *TARGET_PROMOTE_PROTOTYPES
>> *(http://goo.gl/2pQQ) and set it to the default value which is FALSE.
>>
>> static bool
>> sparc_promote_prototypes (const_tree fntype ATTRIBUTE_UNUSED)
>> {
>>   return TARGET_ARCH32 ? true : false;
>> }
>>
>> was replaced by
>>
>> static bool
>> sparc_promote_prototypes (const_tree fntype ATTRIBUTE_UNUSED)
>> {
>>   return false;
>> }
>>     
>
> As mentioned in the PR, this will result in ABI violations.  But, in fact, 
> this is already visible in the modified assembly code:
>
>   
>> 000102b4 <main>:
>>    102b4:    9d e3 bf 98     save  %sp, -104, %sp
>>    102b8:    82 10 20 01     mov  1, %g1
>>    102bc:    c2 37 bf fc     sth  %g1, [ %fp + -4 ]
>>    102c0:    c2 2f bf ff     stb  %g1, [ %fp + -1 ]
>>    102c4:    c2 2f bf fe     stb  %g1, [ %fp + -2 ]
>>    102c8:    d0 0f bf ff     ldub  [ %fp + -1 ], %o0
>>    102cc:    d2 17 bf fc     lduh  [ %fp + -4 ], %o1
>>    102d0:    7f ff ff df     call  1024c <somme>
>>    102d4:    01 00 00 00     nop
>>     
>
> The ABI says that %o1 should be sign-extended since it's for a 'short'.  It is 
> now zero-extended, so this isn't conforming.
>
>