[Mesa-dev] [PATCH 11/14] i965/compaction: Add support for G45.

[Matt Turner]

On Tue, Sep 23, 2014 at 1:19 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> On Thu, Aug 28, 2014 at 8:10 PM, Matt Turner <mattst88 at gmail.com> wrote:
>>     int offset = 0;
>> @@ -1319,17 +1323,22 @@ brw_compact_instructions(struct brw_compile *p,
>> int start_offset,
>>           offset += sizeof(brw_compact_inst);
>>        } else {
>>           /* It appears that the end of thread SEND instruction needs to
>> be
>> -          * aligned, or the GPU hangs.
>> +          * aligned, or the GPU hangs. All uncompacted instructions need
>> to be
>> +          * aligned on G45.
>>            */
>> -         if ((brw_inst_opcode(brw, src) == BRW_OPCODE_SEND ||
>> -              brw_inst_opcode(brw, src) == BRW_OPCODE_SENDC) &&
>> -             brw_inst_eot(brw, src) &&
>> -             (offset & sizeof(brw_compact_inst)) != 0) {
>> +         if ((offset & sizeof(brw_compact_inst)) != 0 &&
>> +             (((brw_inst_opcode(brw, src) == BRW_OPCODE_SEND ||
>> +                brw_inst_opcode(brw, src) == BRW_OPCODE_SENDC) &&
>> +               brw_inst_eot(brw, src)) ||
>> +              brw->is_g4x)) {
>>              brw_compact_inst *align = store + offset;
>>              memset(align, 0, sizeof(*align));
>> -            brw_compact_inst_set_opcode(align, BRW_OPCODE_NOP);
>> +            brw_compact_inst_set_opcode(align, brw->is_g4x ?
>> BRW_OPCODE_NENOP :
>> +
>> BRW_OPCODE_NOP);
>>              brw_compact_inst_set_cmpt_control(align, true);
>>              offset += sizeof(brw_compact_inst);
>> +            compacted_count--;
>> +            compacted_counts[src_offset / sizeof(brw_inst)] =
>> compacted_count;
>
>
> Do these two lines really belong in this patch?  They seem completely
> unrelated to stuff on G45.

Yes, because if you have to insert a padding NENOP, you need to update
the compaction_count (which is really a metric of how far offset you
are because of the space saved by compacted instructions).

So, really what it's doing is not considering compacted instructions
as saving space if we had to insert a padding NENOP after it.