src/compiler/nir/nir_lower_input_attachments.c

   1 /*
   2  * Copyright © 2016 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #include "nir.h"
  25 #include "nir_builder.h"
  26
  27 static nir_ssa_def *
  28 load_frag_coord(nir_builder *b)
  29 {
  30    nir_foreach_variable(var, &b->shader->inputs) {
  31       if (var->data.location == VARYING_SLOT_POS)
  32          return nir_load_var(b, var);
  33    }
  34
  35    nir_variable *pos = nir_variable_create(b->shader, nir_var_shader_in,
  36                                            glsl_vec4_type(), NULL);
  37    pos->data.location = VARYING_SLOT_POS;
  38    /**
  39     * From Vulkan spec:
  40     *   "The OriginLowerLeft execution mode must not be used; fragment entry
  41     *    points must declare OriginUpperLeft."
  42     *
  43     * So at this point origin_upper_left should be true
  44     */
  45    assert(b->shader->info.fs.origin_upper_left == true);
  46
  47    return nir_load_var(b, pos);
  48 }
  49
  50 static bool
  51 try_lower_input_load(nir_function_impl *impl, nir_intrinsic_instr *load)
  52 {
  53    nir_deref_instr *deref = nir_src_as_deref(load->src[0]);
  54    assert(glsl_type_is_image(deref->type));
  55
  56    enum glsl_sampler_dim image_dim = glsl_get_sampler_dim(deref->type);
  57    if (image_dim != GLSL_SAMPLER_DIM_SUBPASS &&
  58        image_dim != GLSL_SAMPLER_DIM_SUBPASS_MS)
  59       return false;
  60
  61    const bool multisampled = (image_dim == GLSL_SAMPLER_DIM_SUBPASS_MS);
  62
  63    nir_builder b;
  64    nir_builder_init(&b, impl);
  65    b.cursor = nir_instr_remove(&load->instr);
  66
  67    nir_ssa_def *frag_coord = nir_f2i32(&b, load_frag_coord(&b));
  68    nir_ssa_def *offset = nir_ssa_for_src(&b, load->src[1], 2);
  69    nir_ssa_def *pos = nir_iadd(&b, frag_coord, offset);
  70
  71    nir_ssa_def *layer = nir_load_layer_id(&b);
  72    nir_ssa_def *coord =
  73       nir_vec3(&b, nir_channel(&b, pos, 0), nir_channel(&b, pos, 1), layer);
  74
  75    nir_tex_instr *tex = nir_tex_instr_create(b.shader, 3 + multisampled);
  76
  77    tex->op = nir_texop_txf;
  78    tex->sampler_dim = image_dim;
  79
  80    switch (glsl_get_sampler_result_type(deref->type)) {
  81    case GLSL_TYPE_FLOAT:
  82       tex->dest_type = nir_type_float;
  83       break;
  84    case GLSL_TYPE_INT:
  85       tex->dest_type = nir_type_int;
  86       break;
  87    case GLSL_TYPE_UINT:
  88       tex->dest_type = nir_type_uint;
  89       break;
  90    default:
  91       unreachable("Invalid image type");
  92    }
  93    tex->is_array = true;
  94    tex->is_shadow = false;
  95
  96    tex->texture_index = 0;
  97    tex->sampler_index = 0;
  98
  99    tex->src[0].src_type = nir_tex_src_texture_deref;
 100    tex->src[0].src = nir_src_for_ssa(&deref->dest.ssa);
 101
 102    tex->src[1].src_type = nir_tex_src_coord;
 103    tex->src[1].src = nir_src_for_ssa(coord);
 104    tex->coord_components = 3;
 105
 106    tex->src[2].src_type = nir_tex_src_lod;
 107    tex->src[2].src = nir_src_for_ssa(nir_imm_int(&b, 0));
 108
 109    if (image_dim == GLSL_SAMPLER_DIM_SUBPASS_MS) {
 110       tex->op = nir_texop_txf_ms;
 111       tex->src[3].src_type = nir_tex_src_ms_index;
 112       tex->src[3].src = load->src[2];
 113    }
 114
 115    nir_ssa_dest_init(&tex->instr, &tex->dest, 4, 32, NULL);
 116    nir_builder_instr_insert(&b, &tex->instr);
 117
 118    nir_ssa_def_rewrite_uses(&load->dest.ssa,
 119                             nir_src_for_ssa(&tex->dest.ssa));
 120
 121    return true;
 122 }
 123
 124 bool
 125 nir_lower_input_attachments(nir_shader *shader)
 126 {
 127    assert(shader->info.stage == MESA_SHADER_FRAGMENT);
 128    bool progress = false;
 129
 130    nir_foreach_function(function, shader) {
 131       if (!function->impl)
 132          continue;
 133
 134       nir_foreach_block(block, function->impl) {
 135          nir_foreach_instr_safe(instr, block) {
 136             if (instr->type != nir_instr_type_intrinsic)
 137                continue;
 138
 139             nir_intrinsic_instr *load = nir_instr_as_intrinsic(instr);
 140
 141             if (load->intrinsic != nir_intrinsic_image_deref_load)
 142                continue;
 143
 144             progress |= try_lower_input_load(function->impl, load);
 145          }
 146       }
 147    }
 148
 149    return progress;
 150 }