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

[Matt Turner]

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

> +
> +   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
>