mesa/src/compiler/nir/nir_lower_input_attachments.c

/*
 * Copyright © 2016 Intel Corporation
 *
 * 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
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 */

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

static nir_def *
load_frag_coord(nir_builder *b, nir_deref_instr *deref,
                const nir_input_attachment_options *options)
{
   if (options->use_fragcoord_sysval) {
      nir_def *frag_coord = nir_load_frag_coord(b);
      if (options->unscaled_input_attachment_ir3 ||
          options->unscaled_depth_stencil_ir3) {
         nir_variable *var = nir_deref_instr_get_variable(deref);
         unsigned base = var->data.index;
         nir_def *unscaled_frag_coord = nir_load_frag_coord_unscaled_ir3(b);
         if (deref->deref_type == nir_deref_type_array &&
             options->unscaled_input_attachment_ir3) {
            nir_def *unscaled =
               nir_i2b(b, nir_iand(b, nir_ishr(b, nir_imm_int(b, options->unscaled_input_attachment_ir3 >> base), deref->arr.index.ssa),
                                   nir_imm_int(b, 1)));
            frag_coord = nir_bcsel(b, unscaled, unscaled_frag_coord, frag_coord);
         } else {
            assert(deref->deref_type == nir_deref_type_var);
            bool unscaled = base == NIR_VARIABLE_NO_INDEX ? options->unscaled_depth_stencil_ir3 : ((options->unscaled_input_attachment_ir3 >> base) & 1);
            frag_coord = unscaled ? unscaled_frag_coord : frag_coord;
         }
      }
      return frag_coord;
   }

   nir_variable *pos = nir_get_variable_with_location(b->shader, nir_var_shader_in,
                                                      VARYING_SLOT_POS, glsl_vec4_type());

   /**
    * From Vulkan spec:
    *   "The OriginLowerLeft execution mode must not be used; fragment entry
    *    points must declare OriginUpperLeft."
    *
    * So at this point origin_upper_left should be true
    */
   assert(b->shader->info.fs.origin_upper_left == true);

   return nir_load_var(b, pos);
}

static nir_def *
load_layer_id(nir_builder *b, const nir_input_attachment_options *options)
{
   if (options->use_layer_id_sysval) {
      if (options->use_view_id_for_layer)
         return nir_load_view_index(b);
      else
         return nir_load_layer_id(b);
   }

   gl_varying_slot slot = options->use_view_id_for_layer ? VARYING_SLOT_VIEW_INDEX : VARYING_SLOT_LAYER;
   nir_variable *layer_id = nir_get_variable_with_location(b->shader, nir_var_shader_in,
                                                           slot, glsl_int_type());
   layer_id->data.interpolation = INTERP_MODE_FLAT;

   return nir_load_var(b, layer_id);
}

static bool
try_lower_input_load(nir_builder *b, nir_intrinsic_instr *load,
                     const nir_input_attachment_options *options)
{
   nir_deref_instr *deref = nir_src_as_deref(load->src[0]);
   assert(glsl_type_is_image(deref->type));

   enum glsl_sampler_dim image_dim = glsl_get_sampler_dim(deref->type);
   if (image_dim != GLSL_SAMPLER_DIM_SUBPASS &&
       image_dim != GLSL_SAMPLER_DIM_SUBPASS_MS)
      return false;

   const bool multisampled = (image_dim == GLSL_SAMPLER_DIM_SUBPASS_MS);

   b->cursor = nir_instr_remove(&load->instr);

   nir_def *frag_coord = load_frag_coord(b, deref, options);
   frag_coord = nir_f2i32(b, frag_coord);
   nir_def *offset = nir_trim_vector(b, load->src[1].ssa, 2);
   nir_def *pos = nir_iadd(b, frag_coord, offset);

   nir_def *layer = load_layer_id(b, options);
   nir_def *coord =
      nir_vec3(b, nir_channel(b, pos, 0), nir_channel(b, pos, 1), layer);

   nir_tex_instr *tex = nir_tex_instr_create(b->shader, 3 + multisampled);

   tex->op = nir_texop_txf;
   tex->sampler_dim = image_dim;

   tex->dest_type =
      nir_get_nir_type_for_glsl_base_type(glsl_get_sampler_result_type(deref->type));
   tex->is_array = true;
   tex->is_shadow = false;
   tex->is_sparse = load->intrinsic == nir_intrinsic_image_deref_sparse_load;

   tex->texture_index = 0;
   tex->sampler_index = 0;

   tex->src[0] = nir_tex_src_for_ssa(nir_tex_src_texture_deref,
                                     &deref->def);
   tex->src[1] = nir_tex_src_for_ssa(nir_tex_src_coord, coord);
   tex->coord_components = 3;

   tex->src[2] = nir_tex_src_for_ssa(nir_tex_src_lod, nir_imm_int(b, 0));

   if (image_dim == GLSL_SAMPLER_DIM_SUBPASS_MS) {
      tex->op = nir_texop_txf_ms;
      tex->src[3].src_type = nir_tex_src_ms_index;
      tex->src[3].src = load->src[2];
   }

   tex->texture_non_uniform = nir_intrinsic_access(load) & ACCESS_NON_UNIFORM;

   nir_def_init(&tex->instr, &tex->def, nir_tex_instr_dest_size(tex), 32);
   nir_builder_instr_insert(b, &tex->instr);

   if (tex->is_sparse) {
      unsigned load_result_size = load->def.num_components - 1;
      nir_component_mask_t load_result_mask = nir_component_mask(load_result_size);
      nir_def *res = nir_channels(
         b, &tex->def, load_result_mask | 0x10);

      nir_def_rewrite_uses(&load->def, res);
   } else {
      nir_def_rewrite_uses(&load->def,
                           &tex->def);
   }

   return true;
}

static bool
try_lower_input_texop(nir_builder *b, nir_tex_instr *tex,
                      const nir_input_attachment_options *options)
{
   const int texture_src_idx =
      nir_tex_instr_src_index(tex, nir_tex_src_texture_deref);
   if (texture_src_idx < 0)
      return false;

   nir_deref_instr *deref = nir_src_as_deref(tex->src[texture_src_idx].src);

   if (glsl_get_sampler_dim(deref->type) != GLSL_SAMPLER_DIM_SUBPASS_MS)
      return false;

   const int coord_src_idx = nir_tex_instr_src_index(tex, nir_tex_src_coord);
   assert(coord_src_idx >= 0);

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

   nir_def *frag_coord = load_frag_coord(b, deref, options);
   frag_coord = nir_f2i32(b, frag_coord);

   nir_def *offset = nir_trim_vector(b, tex->src[coord_src_idx].src.ssa, 2);
   nir_def *pos = nir_iadd(b, frag_coord, offset);

   nir_def *layer = load_layer_id(b, options);
   nir_def *coord = nir_vec3(b, nir_channel(b, pos, 0),
                             nir_channel(b, pos, 1), layer);

   tex->coord_components = 3;

   nir_src_rewrite(&tex->src[coord_src_idx].src, coord);

   return true;
}

static bool
lower_input_attachments_instr(nir_builder *b, nir_instr *instr, void *_data)
{
   const nir_input_attachment_options *options = _data;

   switch (instr->type) {
   case nir_instr_type_tex: {
      nir_tex_instr *tex = nir_instr_as_tex(instr);

      if (tex->op == nir_texop_fragment_mask_fetch_amd ||
          tex->op == nir_texop_fragment_fetch_amd)
         return try_lower_input_texop(b, tex, options);

      return false;
   }
   case nir_instr_type_intrinsic: {
      nir_intrinsic_instr *load = nir_instr_as_intrinsic(instr);

      if (load->intrinsic == nir_intrinsic_image_deref_load ||
          load->intrinsic == nir_intrinsic_image_deref_sparse_load)
         return try_lower_input_load(b, load, options);

      return false;
   }

   default:
      return false;
   }
}

bool
nir_lower_input_attachments(nir_shader *shader,
                            const nir_input_attachment_options *options)
{
   assert(shader->info.stage == MESA_SHADER_FRAGMENT);

   return nir_shader_instructions_pass(shader, lower_input_attachments_instr,
                                       nir_metadata_control_flow,
                                       (void *)options);
}