[Mesa-dev] [PATCH 1/5] i965/fs: When doing no work for live interval calculation, do no allocation.

[Kenneth Graunke]

On 05/08/2012 05:59 PM, Eric Anholt wrote:
> When I had a bug causing the backend to never finish optimizing, it
> also sent me deep into swap.  This avoids extra memory allocation per
> trip through optimization, and thus may reduce the peak memory
> allocation of the driver even in the success case.
> ---
>   src/mesa/drivers/dri/i965/brw_fs_live_variables.cpp |   14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_live_variables.cpp b/src/mesa/drivers/dri/i965/brw_fs_live_variables.cpp
> index c6f0fbc..c7ee582 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_live_variables.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_live_variables.cpp
> @@ -163,12 +163,17 @@ void
>   fs_visitor::calculate_live_intervals()
>   {
>      int num_vars = this->virtual_grf_next;
> -   int *def = ralloc_array(mem_ctx, int, num_vars);
> -   int *use = ralloc_array(mem_ctx, int, num_vars);
>
>      if (this->live_intervals_valid)
>         return;
>
> +   int *def = ralloc_array(mem_ctx, int, num_vars);
> +   int *use = ralloc_array(mem_ctx, int, num_vars);
> +   ralloc_free(this->virtual_grf_def);
> +   ralloc_free(this->virtual_grf_use);
> +   this->virtual_grf_def = def;
> +   this->virtual_grf_use = use;
> +
>      for (int i = 0; i<  num_vars; i++) {
>         def[i] = MAX_INSTRUCTION;
>         use[i] = -1;
> @@ -215,11 +220,6 @@ fs_visitor::calculate_live_intervals()
>         }
>      }
>
> -   ralloc_free(this->virtual_grf_def);
> -   ralloc_free(this->virtual_grf_use);
> -   this->virtual_grf_def = def;
> -   this->virtual_grf_use = use;
> -
>      this->live_intervals_valid = true;
>   }
>

Simple enough and seems like a good idea.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>