On 09/26/2012 11:50 PM, Michael Kostylev wrote:
> 
> On Wed Sep 26 17:00:49 2012
> Luca Barbato wrote:
> 
>>> Program received signal SIGSEGV, Segmentation fault.
>>> 0x105e7eb8 in compute_rematrixing_strategy (s=0x10db13a0) at 
>>> /home/mik/src/fate/src/libavcodec/ac3enc_template.c:356
>>> 356                 if (blk && block->num_rematrixing_bands != 
>>> block0->num_rematrixing_bands)
>>>
>>> For some reason the whole expression is evaluted even if blk==0 while 
>>> block0 is uninitialized.
>>>
>>
>> Could you please provide the assembly for that function?
> 
>    0x105e7e58 <ff_ac3_fixed_encode_frame+1216>: ld      s0,56(sp)
>    0x105e7e5c <ff_ac3_fixed_encode_frame+1220>: jr      ra
>    0x105e7e60 <ff_ac3_fixed_encode_frame+1224>: addiu   sp,sp,144
>    0x105e7e64 <ff_ac3_fixed_encode_frame+1228>: blez    v0,0x105e7ca4 
> <ff_ac3_fixed_encode_frame+780>
>    0x105e7e68 <ff_ac3_fixed_encode_frame+1232>: lw      ra,32(sp)
>    0x105e7e6c <ff_ac3_fixed_encode_frame+1236>: addiu   s1,s8,3004
>    0x105e7e70 <ff_ac3_fixed_encode_frame+1240>: move    s5,zero
>    0x105e7e74 <ff_ac3_fixed_encode_frame+1244>: li      v1,1
>    0x105e7e78 <ff_ac3_fixed_encode_frame+1248>: lw      v0,60(s1)
>    0x105e7e7c <ff_ac3_fixed_encode_frame+1252>: sltiu   a0,s5,1
>    0x105e7e80 <ff_ac3_fixed_encode_frame+1256>: sb      a0,47(s1)
>    0x105e7e84 <ff_ac3_fixed_encode_frame+1260>: li      a0,4
>    0x105e7e88 <ff_ac3_fixed_encode_frame+1264>: mtlo    s1
>    0x105e7e8c <ff_ac3_fixed_encode_frame+1268>: beqz    v0,0x105e7ec8 
> <ff_ac3_fixed_encode_frame+1328>
>    0x105e7e90 <ff_ac3_fixed_encode_frame+1272>: sw      a0,48(s1)
>    0x105e7e94 <ff_ac3_fixed_encode_frame+1276>: lw      v0,3904(s8)
>    0x105e7e98 <ff_ac3_fixed_encode_frame+1280>: li      a1,4
>    0x105e7e9c <ff_ac3_fixed_encode_frame+1284>: slti    a0,v0,62
>    0x105e7ea0 <ff_ac3_fixed_encode_frame+1288>: xori    v0,v0,0x25
>    0x105e7ea4 <ff_ac3_fixed_encode_frame+1292>: subu    a0,a1,a0
>    0x105e7ea8 <ff_ac3_fixed_encode_frame+1296>: sltiu   v0,v0,1
>    0x105e7eac <ff_ac3_fixed_encode_frame+1300>: subu    v0,a0,v0
>    0x105e7eb0 <ff_ac3_fixed_encode_frame+1304>: beqz    s5,0x105e7ec8 
> <ff_ac3_fixed_encode_frame+1328>
>    0x105e7eb4 <ff_ac3_fixed_encode_frame+1308>: sw      v0,48(s1)
> => 0x105e7eb8 <ff_ac3_fixed_encode_frame+1312>: lw      a0,48(ra)
>    0x105e7ebc <ff_ac3_fixed_encode_frame+1316>: bnel    v0,a0,0x105e7ec8 
> <ff_ac3_fixed_encode_frame+1328>
>    0x105e7ec0 <ff_ac3_fixed_encode_frame+1320>: sb      v1,47(s1)
>    0x105e7ec4 <ff_ac3_fixed_encode_frame+1324>: nop
>    0x105e7ec8 <ff_ac3_fixed_encode_frame+1328>: lw      v0,3972(s8)
>    0x105e7ecc <ff_ac3_fixed_encode_frame+1332>: lw      t9,104(s1)
>    0x105e7ed0 <ff_ac3_fixed_encode_frame+1336>: beqz    v0,0x105e8028 
> <ff_ac3_fixed_encode_frame+1680>
>    0x105e7ed4 <ff_ac3_fixed_encode_frame+1340>: lw      s6,108(s1)
> 
>                   zero               at               v0               v1
>  R0           00000000         7400fce1         00000004         00000001 
>                     a0               a1               a2               a3
>  R4           00000004         00000004         00000001         00000000 
>                     a4               a5               a6               a7
>  R8           000062ea         00000024         00000000         00000000 
>                     t0               t1               t2               t3
>  R12          1de18c18         1de18c18         10eb4c94         10eb3494 
>                     s0               s1               s2               s3
>  R16          00000024         10db1fdc         106d3cac         00000004 
>                     s4               s5               s6               s7
>  R20          10db1f60         00000001         00000061         00000004 
>                     t8               t9               k0               k1
>  R24          00000000         00000061         00000000         00000000 
>                     gp               sp               s8               ra
>  R28          10836a20         7fe8cdd0         10db13a0         00000000 
>                 status               lo               hi         badvaddr
>               0400fcf3         10db1fdc         00000000         00000030 
>                  cause               pc
>               10000008         105e7eb8 
>                   fcsr              fir          restart
>               00000004         00770501         00000000 
> 
>> Which compiler were you using?
> 
> The above is gcc-4.8 -march=mips3, also there are at least three minor gcc
> versions where the result is not better.

-O0 fixes the problem?

lu

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