src/glsl/nir/nir_lower_tex.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 typedef struct {
  34    nir_builder b;
  35    const nir_lower_tex_options *options;
  36 } lower_tex_state;
  37
  38 static void
  39 project_src(nir_builder *b, nir_tex_instr *tex)
  40 {
  41    /* Find the projector in the srcs list, if present. */
  42    unsigned proj_index;
  43    for (proj_index = 0; proj_index < tex->num_srcs; proj_index++) {
  44       if (tex->src[proj_index].src_type == nir_tex_src_projector)
  45          break;
  46    }
  47    if (proj_index == tex->num_srcs)
  48       return;
  49
  50    b->cursor = nir_before_instr(&tex->instr);
  51
  52    nir_ssa_def *inv_proj =
  53       nir_frcp(b, nir_ssa_for_src(b, tex->src[proj_index].src, 1));
  54
  55    /* Walk through the sources projecting the arguments. */
  56    for (unsigned i = 0; i < tex->num_srcs; i++) {
  57       switch (tex->src[i].src_type) {
  58       case nir_tex_src_coord:
  59       case nir_tex_src_comparitor:
  60          break;
  61       default:
  62          continue;
  63       }
  64       nir_ssa_def *unprojected =
  65          nir_ssa_for_src(b, tex->src[i].src, nir_tex_instr_src_size(tex, i));
  66       nir_ssa_def *projected = nir_fmul(b, unprojected, inv_proj);
  67
  68       /* Array indices don't get projected, so make an new vector with the
  69        * coordinate's array index untouched.
  70        */
  71       if (tex->is_array && tex->src[i].src_type == nir_tex_src_coord) {
  72          switch (tex->coord_components) {
  73          case 4:
  74             projected = nir_vec4(b,
  75                                  nir_channel(b, projected, 0),
  76                                  nir_channel(b, projected, 1),
  77                                  nir_channel(b, projected, 2),
  78                                  nir_channel(b, unprojected, 3));
  79             break;
  80          case 3:
  81             projected = nir_vec3(b,
  82                                  nir_channel(b, projected, 0),
  83                                  nir_channel(b, projected, 1),
  84                                  nir_channel(b, unprojected, 2));
  85             break;
  86          case 2:
  87             projected = nir_vec2(b,
  88                                  nir_channel(b, projected, 0),
  89                                  nir_channel(b, unprojected, 1));
  90             break;
  91          default:
  92             unreachable("bad texture coord count for array");
  93             break;
  94          }
  95       }
  96
  97       nir_instr_rewrite_src(&tex->instr,
  98                             &tex->src[i].src,
  99                             nir_src_for_ssa(projected));
 100    }
 101
 102    /* Now move the later tex sources down the array so that the projector
 103     * disappears.
 104     */
 105    nir_instr_rewrite_src(&tex->instr, &tex->src[proj_index].src,
 106                          NIR_SRC_INIT);
 107    for (unsigned i = proj_index + 1; i < tex->num_srcs; i++) {
 108       tex->src[i-1].src_type = tex->src[i].src_type;
 109       nir_instr_move_src(&tex->instr, &tex->src[i-1].src, &tex->src[i].src);
 110    }
 111    tex->num_srcs--;
 112 }
 113
 114 static bool
 115 nir_lower_tex_block(nir_block *block, void *void_state)
 116 {
 117    lower_tex_state *state = void_state;
 118    nir_builder *b = &state->b;
 119
 120    nir_foreach_instr_safe(block, instr) {
 121       if (instr->type != nir_instr_type_tex)
 122          continue;
 123
 124       nir_tex_instr *tex = nir_instr_as_tex(instr);
 125       bool lower_txp = !!(state->options->lower_txp & (1 << tex->sampler_dim));
 126
 127       if (lower_txp)
 128          project_src(b, tex);
 129
 130    }
 131
 132    return true;
 133 }
 134
 135 static void
 136 nir_lower_tex_impl(nir_function_impl *impl, lower_tex_state *state)
 137 {
 138    nir_builder_init(&state->b, impl);
 139
 140    nir_foreach_block(impl, nir_lower_tex_block, state);
 141
 142    nir_metadata_preserve(impl, nir_metadata_block_index |
 143                                nir_metadata_dominance);
 144 }
 145
 146 void
 147 nir_lower_tex(nir_shader *shader, const nir_lower_tex_options *options)
 148 {
 149    lower_tex_state state;
 150    state.options = options;
 151    nir_foreach_overload(shader, overload) {
 152       if (overload->impl)
 153          nir_lower_tex_impl(overload->impl, &state);
 154    }
 155 }