Thanks very much Eric for your help and explanations! I'd like to do more but I'm not sure where the modifications should be done. Is there any documentation that might be helpful for such SPARC modifications? Best, Jorge Eric Botcazou wrote: >> 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? >> > > Yes, the code is now correct, but still sub-optimal as the sequence: > > >> 102c4: d2 17 bf fc lduh [ %fp + -4 ], %o1 >> > > >> 102cc: 93 2a 60 10 sll %o1, 0x10, %o1 >> > > >> 102d8: 93 3a 60 10 sra %o1, 0x10, %o1 >> > > could be reduced to just: > > ldsh [ %fp + -4 ], %o1 > > but this requires more work in the back-end. This is actually the bulk of the > work to be done as the extension in the callee that TARGET_PROMOTE_PROTOTYPES > triggers has very likely a marginal effect overall. > > Note that x86, MIPS, HP-PA, m68k, IA-64 and many others have the same setting. > >
