[Mesa-dev] [PATCH 11/11] i965: Use pushed UBO data in the scalar backend.

[Matt Turner]

On Thu, Jul 6, 2017 at 5:22 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> This actually takes advantage of the newly pushed UBO data, avoiding
> pull loads.
>
> XXX: quote performance numbers
> ---
>  src/intel/compiler/brw_fs.cpp     | 35 ++++++++++++++++++++++++++++++++++-
>  src/intel/compiler/brw_fs.h       |  2 ++
>  src/intel/compiler/brw_fs_nir.cpp | 28 ++++++++++++++++++++++++++++
>  3 files changed, 64 insertions(+), 1 deletion(-)
>
> diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
> index 49e714f1c1f..68648eda64d 100644
> --- a/src/intel/compiler/brw_fs.cpp
> +++ b/src/intel/compiler/brw_fs.cpp
> @@ -1386,7 +1386,9 @@ fs_visitor::assign_curb_setup()
>     unsigned uniform_push_length = DIV_ROUND_UP(stage_prog_data->nr_params, 8);
>
>     unsigned ubo_push_length = 0;
> +   unsigned ubo_push_start[4];
>     for (int i = 0; i < 4; i++) {
> +      ubo_push_start[i] = 8 * (ubo_push_length + uniform_push_length);
>        ubo_push_length += stage_prog_data->ubo_ranges[i].length;
>     }
>
> @@ -1398,7 +1400,11 @@ fs_visitor::assign_curb_setup()
>          if (inst->src[i].file == UNIFORM) {
>              int uniform_nr = inst->src[i].nr + inst->src[i].offset / 4;
>              int constant_nr;
> -            if (uniform_nr >= 0 && uniform_nr < (int) uniforms) {
> +            if (inst->src[i].nr >= UBO_START) {
> +               /* constant_nr is in 32-bit units, the rest are in bytes */
> +               constant_nr = ubo_push_start[inst->src[i].nr - UBO_START] +
> +                             inst->src[i].offset / 4;
> +            } else if (uniform_nr >= 0 && uniform_nr < (int) uniforms) {
>                 constant_nr = push_constant_loc[uniform_nr];
>              } else {
>                 /* Section 5.11 of the OpenGL 4.1 spec says:
> @@ -2069,6 +2075,20 @@ fs_visitor::assign_constant_locations()
>     stage_prog_data->nr_params = num_push_constants;
>     stage_prog_data->nr_pull_params = num_pull_constants;
>
> +   /* Now that we know how many regular uniforms we'll push, reduce the
> +    * UBO push ranges so we don't exceed the 3DSTATE_CONSTANT limits.
> +    */
> +   unsigned push_length = DIV_ROUND_UP(stage_prog_data->nr_params, 8);
> +   for (int i = 0; i < 4; i++) {
> +      struct brw_ubo_range *range = &prog_data->ubo_ranges[i];
> +
> +      if (push_length + range->length > 64)
> +         range->length = 64 - push_length;
> +
> +      push_length += range->length;
> +   }
> +   assert(push_length <= 64);
> +
>     /* Up until now, the param[] array has been indexed by reg + offset
>      * of UNIFORM registers.  Move pull constants into pull_param[] and
>      * condense param[] to only contain the uniforms we chose to push.
> @@ -2103,6 +2123,19 @@ fs_visitor::get_pull_locs(const fs_reg &src,
>  {
>     assert(src.file == UNIFORM);
>
> +   if (src.nr >= UBO_START) {
> +      const struct brw_ubo_range *range =
> +         &prog_data->ubo_ranges[src.nr - UBO_START];
> +
> +      /* If this access is in our (reduced) range, use the push data. */
> +      if (src.offset / 32 < range->length && !getenv("PULL"))

If the environment variable is useful, make it part of INTEL_DEBUG?