[Mesa-dev] [PATCH] radv: use nir_opt_find_array_copies()

[Bas Nieuwenhuizen]

Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
On Thu, Oct 18, 2018 at 1:00 AM Timothy Arceri <tarceri at itsqueeze.com> wrote:
>
> Totals from affected shaders:
> SGPRS: 1112 -> 1112 (0.00 %)
> VGPRS: 1492 -> 1196 (-19.84 %)
> Spilled SGPRs: 0 -> 0 (0.00 %)
> Spilled VGPRs: 0 -> 0 (0.00 %)
> Private memory VGPRs: 0 -> 0 (0.00 %)
> Scratch size: 0 -> 0 (0.00 %) dwords per thread
> Code Size: 112172 -> 101316 (-9.68 %) bytes
> LDS: 0 -> 0 (0.00 %) blocks
> Max Waves: 93 -> 98 (5.38 %)
> Wait states: 0 -> 0 (0.00 %)
>
> All affected shaders are from "Batman: Arkham City" over DXVK.
>
> The pass detects that the temporary array created by DXVK for
> storing TCS inputs is a copy of the input arrays and allows
> us to avoid copying all of the input data and then indirecting
> on it with if-ladders, instead we just do indirect indexing.
> ---
>  src/amd/vulkan/radv_pipeline.c |  6 +++---
>  src/amd/vulkan/radv_shader.c   | 22 ++++++++++++++++++----
>  src/amd/vulkan/radv_shader.h   |  3 ++-
>  3 files changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
> index e1d665d0ac7..8d15a048bbf 100644
> --- a/src/amd/vulkan/radv_pipeline.c
> +++ b/src/amd/vulkan/radv_pipeline.c
> @@ -1808,13 +1808,13 @@ radv_link_shaders(struct radv_pipeline *pipeline, nir_shader **shaders)
>                                 ac_lower_indirect_derefs(ordered_shaders[i],
>                                                          pipeline->device->physical_device->rad_info.chip_class);
>                         }
> -                       radv_optimize_nir(ordered_shaders[i], false);
> +                       radv_optimize_nir(ordered_shaders[i], false, false);
>
>                         if (nir_lower_global_vars_to_local(ordered_shaders[i - 1])) {
>                                 ac_lower_indirect_derefs(ordered_shaders[i - 1],
>                                                          pipeline->device->physical_device->rad_info.chip_class);
>                         }
> -                       radv_optimize_nir(ordered_shaders[i - 1], false);
> +                       radv_optimize_nir(ordered_shaders[i - 1], false, false);
>                 }
>         }
>  }
> @@ -2073,7 +2073,7 @@ void radv_create_shaders(struct radv_pipeline *pipeline,
>
>                         if (!(flags & VK_PIPELINE_CREATE_DISABLE_OPTIMIZATION_BIT)) {
>                                 nir_lower_io_to_scalar_early(nir[i], mask);
> -                               radv_optimize_nir(nir[i], false);
> +                               radv_optimize_nir(nir[i], false, false);
>                         }
>                 }
>         }
> diff --git a/src/amd/vulkan/radv_shader.c b/src/amd/vulkan/radv_shader.c
> index 3b3422c8da6..52aa83d4a5a 100644
> --- a/src/amd/vulkan/radv_shader.c
> +++ b/src/amd/vulkan/radv_shader.c
> @@ -118,7 +118,8 @@ void radv_DestroyShaderModule(
>  }
>
>  void
> -radv_optimize_nir(struct nir_shader *shader, bool optimize_conservatively)
> +radv_optimize_nir(struct nir_shader *shader, bool optimize_conservatively,
> +                  bool allow_copies)
>  {
>          bool progress;
>
> @@ -128,6 +129,15 @@ radv_optimize_nir(struct nir_shader *shader, bool optimize_conservatively)
>                  NIR_PASS_V(shader, nir_lower_vars_to_ssa);
>                 NIR_PASS_V(shader, nir_lower_pack);
>
> +               if (allow_copies) {
> +                       /* Only run this pass in the first call to
> +                        * radv_optimize_nir.  Later calls assume that we've
> +                        * lowered away any copy_deref instructions and we
> +                        *  don't want to introduce any more.
> +                       */
> +                       NIR_PASS(progress, shader, nir_opt_find_array_copies);
> +               }
> +
>                 NIR_PASS(progress, shader, nir_opt_copy_prop_vars);
>                 NIR_PASS(progress, shader, nir_opt_dead_write_vars);
>
> @@ -306,7 +316,6 @@ radv_shader_compile_to_nir(struct radv_device *device,
>         }
>
>         nir_split_var_copies(nir);
> -       nir_lower_var_copies(nir);
>
>         nir_lower_global_vars_to_local(nir);
>         nir_remove_dead_variables(nir, nir_var_local);
> @@ -323,7 +332,12 @@ radv_shader_compile_to_nir(struct radv_device *device,
>         nir_lower_load_const_to_scalar(nir);
>
>         if (!(flags & VK_PIPELINE_CREATE_DISABLE_OPTIMIZATION_BIT))
> -               radv_optimize_nir(nir, false);
> +               radv_optimize_nir(nir, false, true);
> +
> +       /* We call nir_lower_var_copies() after the first radv_optimize_nir()
> +        * to remove any copies introduced by nir_opt_find_array_copies().
> +        */
> +       nir_lower_var_copies(nir);
>
>         /* Indirect lowering must be called after the radv_optimize_nir() loop
>          * has been called at least once. Otherwise indirect lowering can
> @@ -331,7 +345,7 @@ radv_shader_compile_to_nir(struct radv_device *device,
>          * considered too large for unrolling.
>          */
>         ac_lower_indirect_derefs(nir, device->physical_device->rad_info.chip_class);
> -       radv_optimize_nir(nir, flags & VK_PIPELINE_CREATE_DISABLE_OPTIMIZATION_BIT);
> +       radv_optimize_nir(nir, flags & VK_PIPELINE_CREATE_DISABLE_OPTIMIZATION_BIT, false);
>
>         return nir;
>  }
> diff --git a/src/amd/vulkan/radv_shader.h b/src/amd/vulkan/radv_shader.h
> index c490b69f52b..22423e5f99a 100644
> --- a/src/amd/vulkan/radv_shader.h
> +++ b/src/amd/vulkan/radv_shader.h
> @@ -298,7 +298,8 @@ struct radv_shader_slab {
>  };
>
>  void
> -radv_optimize_nir(struct nir_shader *shader, bool optimize_conservatively);
> +radv_optimize_nir(struct nir_shader *shader, bool optimize_conservatively,
> +                 bool allow_copies);
>
>  nir_shader *
>  radv_shader_compile_to_nir(struct radv_device *device,
> --
> 2.17.1
>
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