[Mesa-dev] [PATCH 2/4] i965/vec4: Improve CSE performance by expiring some available expressions.

[Matt Turner]

On Mon, Jun 30, 2014 at 11:49 AM, Ian Romanick <idr at freedesktop.org> wrote:
> On 06/25/2014 02:12 PM, Matt Turner wrote:
>> Port of commit 5daf867f to the vec4 code.
>> ---
>>  src/mesa/drivers/dri/i965/brw_vec4_cse.cpp | 20 ++++++++++++++++++++
>>  1 file changed, 20 insertions(+)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
>> index 33c7430..67fc58a 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
>> @@ -128,6 +128,7 @@ vec4_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
>>
>>     void *cse_ctx = ralloc_context(NULL);
>>
>> +   int ip = block->start_ip;
>>     for (vec4_instruction *inst = (vec4_instruction *)block->start;
>>          inst != block->end->next;
>>          inst = (vec4_instruction *) inst->next) {
>> @@ -198,6 +199,8 @@ vec4_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
>>           aeb_entry *entry = (aeb_entry *)entry_node;
>>
>>           for (int i = 0; i < 3; i++) {
>> +            src_reg *src = &entry->generator->src[i];
>> +
>>              /* Kill all AEB entries that use the destination we just
>>               * overwrote.
>>               */
>> @@ -207,8 +210,23 @@ vec4_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
>>                 ralloc_free(entry);
>>                 break;
>>              }
>> +
>> +            /* Kill any AEB entries using registers that don't get reused any
>> +             * more -- a sure sign they'll fail operands_match().
>> +             */
>> +            int last_reg_use = MAX2(MAX2(virtual_grf_end[src->reg * 4 + 0],
>> +                                         virtual_grf_end[src->reg * 4 + 1]),
>> +                                    MAX2(virtual_grf_end[src->reg * 4 + 2],
>> +                                         virtual_grf_end[src->reg * 4 + 3]));
>> +            if (src->file == GRF && last_reg_use < ip) {
>> +               entry->remove();
>> +               ralloc_free(entry);
>> +               break;
>> +            }
>>           }
>>        }
>> +
>> +      ip++;
>>     }
>>
>>     ralloc_free(cse_ctx);
>> @@ -224,6 +242,8 @@ vec4_visitor::opt_cse()
>>  {
>>     bool progress = false;
>>
>> +   calculate_live_intervals();
>> +
>>     cfg_t cfg(&instructions);
>
> Does this also need a rebase on other patches you have pending?

Yep. I'll probably commit the other stuff first, so fix this patch up
before it goes in.