mesa/src/compiler/nir/nir_lower_uniforms_to_ubo.c

/*
 * Copyright 2017 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * on the rights to use, copy, modify, merge, publish, distribute, sub
 * license, and/or sell copies of the Software, and to permit persons to whom
 * the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * Remap load_uniform intrinsics to nir_load_ubo or nir_load_ubo_vec4 accesses
 * of UBO binding point 0. Simultaneously, remap existing UBO accesses by
 * increasing their binding point by 1.
 *
 * For PIPE_CAP_PACKED_UNIFORMS, dword_packed should be set to indicate that
 * nir_intrinsic_load_uniform is in increments of dwords instead of vec4s.
 *
 * If load_vec4 is set, then nir_intrinsic_load_ubo_vec4 will be generated
 * instead of nir_intrinsic_load_ubo, saving addressing math for hardawre
 * needing aligned vec4 loads in increments of vec4s (such as TGSI CONST file
 * loads).
 */

#include "nir.h"
#include "nir_builder.h"

struct nir_lower_uniforms_to_ubo_state {
   bool dword_packed;
   bool load_vec4;
};

static bool
nir_lower_uniforms_to_ubo_instr(nir_builder *b, nir_instr *instr, void *data)
{
   struct nir_lower_uniforms_to_ubo_state *state = data;

   if (instr->type != nir_instr_type_intrinsic)
      return false;

   nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);

   b->cursor = nir_before_instr(&intr->instr);

   /* Increase all UBO binding points by 1. */
   if (intr->intrinsic == nir_intrinsic_load_ubo &&
       !b->shader->info.first_ubo_is_default_ubo) {
      nir_def *old_idx = intr->src[0].ssa;
      nir_def *new_idx = nir_iadd_imm(b, old_idx, 1);
      nir_src_rewrite(&intr->src[0], new_idx);
      return true;
   }

   if (intr->intrinsic == nir_intrinsic_load_uniform) {
      nir_def *ubo_idx = nir_imm_int(b, 0);
      nir_def *uniform_offset = intr->src[0].ssa;

      assert(intr->def.bit_size >= 8);
      nir_def *load_result;
      if (state->load_vec4) {
         /* No asking us to generate load_vec4 when you've packed your uniforms
          * as dwords instead of vec4s.
          */
         assert(!state->dword_packed);
         load_result = nir_load_ubo_vec4(b, intr->num_components, intr->def.bit_size,
                                         ubo_idx, uniform_offset, .base = nir_intrinsic_base(intr));
      } else {
         /* For PIPE_CAP_PACKED_UNIFORMS, the uniforms are packed with the
          * base/offset in dword units instead of vec4 units.
          */
         int multiplier = state->dword_packed ? 4 : 16;
         load_result = nir_load_ubo(b, intr->num_components, intr->def.bit_size,
                                    ubo_idx,
                                    nir_iadd_imm(b, nir_imul_imm(b, uniform_offset, multiplier),
                                                 nir_intrinsic_base(intr) * multiplier));
         nir_intrinsic_instr *load = nir_instr_as_intrinsic(load_result->parent_instr);

         /* If it's const, set the alignment to our known constant offset.  If
          * not, set it to a pessimistic value based on the multiplier (or the
          * scalar size, for qword loads).
          *
          * We could potentially set up stricter alignments for indirects by
          * knowing what features are enabled in the APIs (see comment in
          * nir_lower_ubo_vec4.c)
          */
         if (nir_src_is_const(intr->src[0])) {
            nir_intrinsic_set_align(load, NIR_ALIGN_MUL_MAX,
                                    (nir_src_as_uint(intr->src[0]) +
                                     nir_intrinsic_base(intr) * multiplier) %
                                       NIR_ALIGN_MUL_MAX);
         } else {
            nir_intrinsic_set_align(load, MAX2(multiplier, intr->def.bit_size / 8), 0);
         }

         nir_intrinsic_set_range_base(load, nir_intrinsic_base(intr) * multiplier);
         nir_intrinsic_set_range(load, nir_intrinsic_range(intr) * multiplier);
      }
      nir_def_rewrite_uses(&intr->def, load_result);

      nir_instr_remove(&intr->instr);
      return true;
   }

   return false;
}

bool
nir_lower_uniforms_to_ubo(nir_shader *shader, bool dword_packed, bool load_vec4)
{
   bool progress = false;

   struct nir_lower_uniforms_to_ubo_state state = {
      .dword_packed = dword_packed,
      .load_vec4 = load_vec4,
   };

   progress = nir_shader_instructions_pass(shader,
                                           nir_lower_uniforms_to_ubo_instr,
                                           nir_metadata_block_index |
                                              nir_metadata_dominance,
                                           &state);

   if (progress) {
      if (!shader->info.first_ubo_is_default_ubo) {
         nir_foreach_variable_with_modes(var, shader, nir_var_mem_ubo) {
            var->data.binding++;
            if (var->data.driver_location != -1)
               var->data.driver_location++;
            /* only increment location for ubo arrays */
            if (glsl_without_array(var->type) == var->interface_type &&
                glsl_type_is_array(var->type))
               var->data.location++;
         }
      }
      shader->info.num_ubos++;

      if (shader->num_uniforms > 0) {
         const struct glsl_type *type = glsl_array_type(glsl_vec4_type(),
                                                        shader->num_uniforms, 16);
         nir_variable *ubo = nir_variable_create(shader, nir_var_mem_ubo, type,
                                                 "uniform_0");
         ubo->data.binding = 0;
         ubo->data.explicit_binding = 1;

         struct glsl_struct_field field = {
            .type = type,
            .name = "data",
            .location = -1,
         };
         ubo->interface_type =
            glsl_interface_type(&field, 1, GLSL_INTERFACE_PACKING_STD430,
                                false, "__ubo0_interface");
      }
   }

   shader->info.first_ubo_is_default_ubo = true;
   return progress;
}