[Mesa-dev] [PATCH 2/3] i965/fs: Clear variable from live-set if it's completely overwritten.

[Matt Turner]

On Mon, Apr 14, 2014 at 5:50 PM, Eric Anholt <eric at anholt.net> wrote:
> Matt Turner <mattst88 at gmail.com> writes:
>
>> One program affected:
>>
>> instructions in affected programs:     246 -> 244 (-0.81%)
>> ---
>>  src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp b/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
>> index 6addbb3..1ae7606 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
>> @@ -80,6 +80,13 @@ fs_visitor::dead_code_eliminate()
>>              }
>>           }
>>
>> +         if (inst->dst.file == GRF) {
>> +            if (!inst->is_partial_write()) {
>> +               int var = live_intervals->var_from_reg(&inst->dst);
>> +               BITSET_CLEAR(live, var);
>> +            }
>> +         }
>
> Any more effect if you:
>
>  +               int var = live_intervals->var_from_vgrf[inst->dst.reg];
>  +               for (int i = 0; i < inst->regs_written; i++)
>  +                  BITSET_CLEAR(live, var + i);
>
> instead?

Needs to be BITSET_CLEAR(live, var + inst->dst.reg_offset + i), but
nope. No changes.