[Mesa-dev] [PATCH 09/11] i965/vec4: Define helpers to calculate the common live interval of a range of variables.

Francisco Jerez currojerez at riseup.net
Fri Mar 20 11:05:29 PDT 2015


Matt Turner <mattst88 at gmail.com> writes:

> On Fri, Mar 20, 2015 at 7:50 AM, Francisco Jerez <currojerez at riseup.net> wrote:
>> These will be especially useful when we start keeping track of
>> liveness information for each subregister.
>> ---
>>  src/mesa/drivers/dri/i965/brw_vec4.cpp             |  6 +--
>>  src/mesa/drivers/dri/i965/brw_vec4.h               |  2 +
>>  src/mesa/drivers/dri/i965/brw_vec4_cse.cpp         |  8 +---
>>  .../drivers/dri/i965/brw_vec4_live_variables.cpp   | 44 +++++++++++++---------
>>  4 files changed, 31 insertions(+), 29 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> index ce02fe3..30bbb9b 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> @@ -25,6 +25,7 @@
>>  #include "brw_fs.h"
>>  #include "brw_cfg.h"
>>  #include "brw_vs.h"
>> +#include "brw_vec4_live_variables.h"
>>  #include "brw_dead_control_flow.h"
>>
>>  extern "C" {
>> @@ -1001,10 +1002,7 @@ vec4_visitor::opt_register_coalesce()
>>        /* Can't coalesce this GRF if someone else was going to
>>         * read it later.
>>         */
>> -      if (this->virtual_grf_end[inst->src[0].reg * 4 + 0] > ip ||
>> -          this->virtual_grf_end[inst->src[0].reg * 4 + 1] > ip ||
>> -          this->virtual_grf_end[inst->src[0].reg * 4 + 2] > ip ||
>> -          this->virtual_grf_end[inst->src[0].reg * 4 + 3] > ip)
>> +      if (var_range_end(var_from_reg(alloc, inst->src[0]), 4) > ip)
>>          continue;
>>
>>        /* We need to check interference with the final destination between this
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
>> index 50b9921..f1b3000 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4.h
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4.h
>> @@ -201,6 +201,8 @@ public:
>>     bool opt_vector_float();
>>     bool opt_reduce_swizzle();
>>     bool dead_code_eliminate();
>> +   int var_range_start(unsigned var, unsigned n) const;
>> +   int var_range_end(unsigned var, unsigned n) const;
>>     bool virtual_grf_interferes(int a, int b);
>>     bool opt_copy_propagation(bool do_constant_prop = true);
>>     bool opt_cse_local(bblock_t *block);
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
>> index d7fb452..9147c3c 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
>> @@ -234,13 +234,7 @@ vec4_visitor::opt_cse_local(bblock_t *block)
>>               * more -- a sure sign they'll fail operands_match().
>>               */
>>              if (src->file == GRF) {
>> -               assert((unsigned)(src->reg * 4 + 3) < (alloc.count * 4));
>> -
>> -               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 (last_reg_use < ip) {
>> +               if (var_range_end(var_from_reg(alloc, *src), 4) < ip) {
>>                    entry->remove();
>>                    ralloc_free(entry);
>>                    break;
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
>> index 5b2e13c..4b87af2 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
>> @@ -300,25 +300,33 @@ vec4_visitor::invalidate_live_intervals()
>>     live_intervals = NULL;
>>  }
>>
>> +int
>> +vec4_visitor::var_range_start(unsigned var, unsigned n) const
>> +{
>> +   int start = INT_MAX;
>> +
>> +   for (unsigned i = 0; i < n; ++i)
>
> ++i, the mark of a C++ programmer :)
>
>> +      start = MIN2(start, virtual_grf_start[v + i]);
>
> v -> var
>
Oops, I squashed the fix into PATCH 10 by mistake, I'll fix that.

Thanks!

>> +
>> +   return start;
>> +}
>> +
>> +int
>> +vec4_visitor::var_range_end(unsigned var, unsigned n) const
>> +{
>> +   int end = INT_MIN;
>> +
>> +   for (unsigned i = 0; i < n; ++i)
>> +      end = MAX2(end, virtual_grf_end[var + i]);
>> +
>> +   return end;
>> +}
>> +
>>  bool
>>  vec4_visitor::virtual_grf_interferes(int a, int b)
>>  {
>> -   int start_a = MIN2(MIN2(virtual_grf_start[a * 4 + 0],
>> -                           virtual_grf_start[a * 4 + 1]),
>> -                      MIN2(virtual_grf_start[a * 4 + 2],
>> -                           virtual_grf_start[a * 4 + 3]));
>> -   int start_b = MIN2(MIN2(virtual_grf_start[b * 4 + 0],
>> -                           virtual_grf_start[b * 4 + 1]),
>> -                      MIN2(virtual_grf_start[b * 4 + 2],
>> -                           virtual_grf_start[b * 4 + 3]));
>> -   int end_a = MAX2(MAX2(virtual_grf_end[a * 4 + 0],
>> -                         virtual_grf_end[a * 4 + 1]),
>> -                    MAX2(virtual_grf_end[a * 4 + 2],
>> -                         virtual_grf_end[a * 4 + 3]));
>> -   int end_b = MAX2(MAX2(virtual_grf_end[b * 4 + 0],
>> -                         virtual_grf_end[b * 4 + 1]),
>> -                    MAX2(virtual_grf_end[b * 4 + 2],
>> -                         virtual_grf_end[b * 4 + 3]));
>> -   return !(end_a <= start_b ||
>> -            end_b <= start_a);
>> +   return !((virtual_grf_range_end(4 * a, 4) <=
>> +             virtual_grf_range_start(4 * b, 4)) ||
>> +            (virtual_grf_range_end(4 * b, 4) <=
>> +             virtual_grf_range_start(4 * a, 4)));
>>  }
>> --
>> 2.1.3
>>
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