src/glsl/nir/nir_lower_tex_projector.c

   1 /*
   2  * Copyright © 2015 Broadcom
   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 /*
  25  * This lowering pass converts the coordinate division for texture projection
  26  * to be done in ALU instructions instead of asking the texture operation to
  27  * do so.
  28  */
  29
  30 #include "nir.h"
  31 #include "nir_builder.h"
  32
  33 static nir_ssa_def *
  34 channel(nir_builder *b, nir_ssa_def *def, int c)
  35 {
  36    return nir_swizzle(b, def, (unsigned[4]){c, c, c, c}, 1, false);
  37 }
  38
  39 static bool
  40 nir_lower_tex_projector_block(nir_block *block, void *void_state)
  41 {
  42    nir_builder *b = void_state;
  43
  44    nir_foreach_instr_safe(block, instr) {
  45       if (instr->type != nir_instr_type_tex)
  46          continue;
  47
  48       nir_tex_instr *tex = nir_instr_as_tex(instr);
  49       nir_builder_insert_before_instr(b, &tex->instr);
  50
  51       /* Find the projector in the srcs list, if present. */
  52       int proj_index;
  53       for (proj_index = 0; proj_index < tex->num_srcs; proj_index++) {
  54          if (tex->src[proj_index].src_type == nir_tex_src_projector)
  55             break;
  56       }
  57       if (proj_index == tex->num_srcs)
  58          continue;
  59       nir_ssa_def *inv_proj =
  60          nir_frcp(b, nir_ssa_for_src(b, tex->src[proj_index].src, 1));
  61
  62       /* Walk through the sources projecting the arguments. */
  63       for (int i = 0; i < tex->num_srcs; i++) {
  64          switch (tex->src[i].src_type) {
  65          case nir_tex_src_coord:
  66          case nir_tex_src_comparitor:
  67             break;
  68          default:
  69             continue;
  70          }
  71          nir_ssa_def *unprojected =
  72             nir_ssa_for_src(b, tex->src[i].src, nir_tex_instr_src_size(tex, i));
  73          nir_ssa_def *projected = nir_fmul(b, unprojected, inv_proj);
  74
  75          /* Array indices don't get projected, so make an new vector with the
  76           * coordinate's array index untouched.
  77           */
  78          if (tex->is_array && tex->src[i].src_type == nir_tex_src_coord) {
  79             switch (tex->coord_components) {
  80             case 4:
  81                projected = nir_vec4(b,
  82                                     channel(b, projected, 0),
  83                                     channel(b, projected, 1),
  84                                     channel(b, projected, 2),
  85                                     channel(b, unprojected, 3));
  86                break;
  87             case 3:
  88                projected = nir_vec3(b,
  89                                     channel(b, projected, 0),
  90                                     channel(b, projected, 1),
  91                                     channel(b, unprojected, 2));
  92                break;
  93             case 2:
  94                projected = nir_vec2(b,
  95                                     channel(b, projected, 0),
  96                                     channel(b, unprojected, 1));
  97                break;
  98             default:
  99                unreachable("bad texture coord count for array");
 100                break;
 101             }
 102          }
 103
 104          nir_instr_rewrite_src(&tex->instr,
 105                                &tex->src[i].src,
 106                                nir_src_for_ssa(projected));
 107       }
 108
 109       /* Now move the later tex sources down the array so that the projector
 110        * disappears.
 111        */
 112       nir_instr_rewrite_src(&tex->instr, &tex->src[proj_index].src,
 113                             NIR_SRC_INIT);
 114       for (int i = proj_index + 1; i < tex->num_srcs; i++) {
 115          tex->src[i-1].src_type = tex->src[i].src_type;
 116          nir_instr_move_src(&tex->instr, &tex->src[i-1].src, &tex->src[i].src);
 117       }
 118       tex->num_srcs--;
 119    }
 120
 121    return true;
 122 }
 123
 124 static void
 125 nir_lower_tex_projector_impl(nir_function_impl *impl)
 126 {
 127    nir_builder b;
 128    nir_builder_init(&b, impl);
 129
 130    nir_foreach_block(impl, nir_lower_tex_projector_block, &b);
 131
 132    nir_metadata_preserve(impl, nir_metadata_block_index |
 133                                nir_metadata_dominance);
 134 }
 135
 136 void
 137 nir_lower_tex_projector(nir_shader *shader)
 138 {
 139    nir_foreach_overload(shader, overload) {
 140       if (overload->impl)
 141          nir_lower_tex_projector_impl(overload->impl);
 142    }
 143 }