src/compiler/nir/nir_lower_io_to_scalar.c

   1 /*
   2  * Copyright © 2016 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 #include "nir.h"
  25 #include "nir_builder.h"
  26
  27 /** @file nir_lower_io_to_scalar.c
  28  *
  29  * Replaces nir_load_input/nir_store_output operations with num_components !=
  30  * 1 with individual per-channel operations.
  31  */
  32
  33 static void
  34 lower_load_input_to_scalar(nir_builder *b, nir_intrinsic_instr *intr)
  35 {
  36    b->cursor = nir_before_instr(&intr->instr);
  37
  38    assert(intr->dest.is_ssa);
  39
  40    nir_ssa_def *loads[4];
  41
  42    for (unsigned i = 0; i < intr->num_components; i++) {
  43       nir_intrinsic_instr *chan_intr =
  44          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
  45       nir_ssa_dest_init(&chan_intr->instr, &chan_intr->dest,
  46                         1, intr->dest.ssa.bit_size, NULL);
  47       chan_intr->num_components = 1;
  48
  49       nir_intrinsic_set_base(chan_intr, nir_intrinsic_base(intr));
  50       nir_intrinsic_set_component(chan_intr, nir_intrinsic_component(intr) + i);
  51       /* offset */
  52       nir_src_copy(&chan_intr->src[0], &intr->src[0], chan_intr);
  53
  54       nir_builder_instr_insert(b, &chan_intr->instr);
  55
  56       loads[i] = &chan_intr->dest.ssa;
  57    }
  58
  59    nir_ssa_def_rewrite_uses(&intr->dest.ssa,
  60                             nir_src_for_ssa(nir_vec(b, loads,
  61                                                     intr->num_components)));
  62    nir_instr_remove(&intr->instr);
  63 }
  64
  65 static void
  66 lower_store_output_to_scalar(nir_builder *b, nir_intrinsic_instr *intr)
  67 {
  68    b->cursor = nir_before_instr(&intr->instr);
  69
  70    nir_ssa_def *value = nir_ssa_for_src(b, intr->src[0], intr->num_components);
  71
  72    for (unsigned i = 0; i < intr->num_components; i++) {
  73       if (!(nir_intrinsic_write_mask(intr) & (1 << i)))
  74          continue;
  75
  76       nir_intrinsic_instr *chan_intr =
  77          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
  78       chan_intr->num_components = 1;
  79
  80       nir_intrinsic_set_base(chan_intr, nir_intrinsic_base(intr));
  81       nir_intrinsic_set_write_mask(chan_intr, 0x1);
  82       nir_intrinsic_set_component(chan_intr, nir_intrinsic_component(intr) + i);
  83
  84       /* value */
  85       chan_intr->src[0] = nir_src_for_ssa(nir_channel(b, value, i));
  86       /* offset */
  87       nir_src_copy(&chan_intr->src[1], &intr->src[1], chan_intr);
  88
  89       nir_builder_instr_insert(b, &chan_intr->instr);
  90    }
  91
  92    nir_instr_remove(&intr->instr);
  93 }
  94
  95 void
  96 nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode mask)
  97 {
  98    nir_foreach_function(function, shader) {
  99       if (function->impl) {
 100          nir_builder b;
 101          nir_builder_init(&b, function->impl);
 102
 103          nir_foreach_block(block, function->impl) {
 104             nir_foreach_instr_safe(instr, block) {
 105                if (instr->type != nir_instr_type_intrinsic)
 106                   continue;
 107
 108                nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 109
 110                if (intr->num_components == 1)
 111                   continue;
 112
 113                switch (intr->intrinsic) {
 114                case nir_intrinsic_load_input:
 115                   if (mask & nir_var_shader_in)
 116                      lower_load_input_to_scalar(&b, intr);
 117                   break;
 118                case nir_intrinsic_store_output:
 119                   if (mask & nir_var_shader_out)
 120                      lower_store_output_to_scalar(&b, intr);
 121                   break;
 122                default:
 123                   break;
 124                }
 125             }
 126          }
 127       }
 128    }
 129 }
 130
 131 static nir_variable **
 132 get_channel_variables(struct hash_table *ht, nir_variable *var)
 133 {
 134    nir_variable **chan_vars;
 135    struct hash_entry *entry = _mesa_hash_table_search(ht, var);
 136    if (!entry) {
 137       chan_vars = (nir_variable **) calloc(4, sizeof(nir_variable *));
 138       _mesa_hash_table_insert(ht, var, chan_vars);
 139    } else {
 140       chan_vars = (nir_variable **) entry->data;
 141    }
 142
 143    return chan_vars;
 144 }
 145
 146 /*
 147  * This function differs from nir_deref_clone() in that it gets its type from
 148  * the parent deref rather than our source deref. This is useful when splitting
 149  * vectors because we want to use the scalar type of the new parent rather than
 150  * then the old vector type.
 151  */
 152 static nir_deref_array *
 153 clone_deref_array(const nir_deref_array *darr, nir_deref *parent)
 154 {
 155    nir_deref_array *ndarr = nir_deref_array_create(parent);
 156
 157    ndarr->deref.type = glsl_get_array_element(parent->type);
 158    if (darr->deref.child)
 159       ndarr->deref.child =
 160          &clone_deref_array(nir_deref_as_array(darr->deref.child),
 161                             &ndarr->deref)->deref;
 162
 163    ndarr->deref_array_type = darr->deref_array_type;
 164    ndarr->base_offset = darr->base_offset;
 165    if (ndarr->deref_array_type == nir_deref_array_type_indirect)
 166      nir_src_copy(&ndarr->indirect, &darr->indirect, parent);
 167
 168    return ndarr;
 169 }
 170
 171 static void
 172 lower_load_to_scalar_early(nir_builder *b, nir_intrinsic_instr *intr,
 173                            nir_variable *var, struct hash_table *split_inputs,
 174                            struct hash_table *split_outputs)
 175 {
 176    b->cursor = nir_before_instr(&intr->instr);
 177
 178    assert(intr->dest.is_ssa);
 179
 180    nir_ssa_def *loads[4];
 181
 182    nir_variable **chan_vars;
 183    if (var->data.mode == nir_var_shader_in) {
 184       chan_vars = get_channel_variables(split_inputs, var);
 185    } else {
 186       chan_vars = get_channel_variables(split_outputs, var);
 187    }
 188
 189    for (unsigned i = 0; i < intr->num_components; i++) {
 190       nir_variable *chan_var = chan_vars[var->data.location_frac + i];
 191       if (!chan_vars[var->data.location_frac + i]) {
 192          chan_var = nir_variable_clone(var, b->shader);
 193          chan_var->data.location_frac =  var->data.location_frac + i;
 194          chan_var->type = glsl_channel_type(chan_var->type);
 195
 196          chan_vars[var->data.location_frac + i] = chan_var;
 197
 198          nir_shader_add_variable(b->shader, chan_var);
 199       }
 200
 201       nir_intrinsic_instr *chan_intr =
 202          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
 203       nir_ssa_dest_init(&chan_intr->instr, &chan_intr->dest,
 204                         1, intr->dest.ssa.bit_size, NULL);
 205       chan_intr->num_components = 1;
 206       chan_intr->variables[0] = nir_deref_var_create(chan_intr, chan_var);
 207
 208       if (intr->variables[0]->deref.child) {
 209          chan_intr->variables[0]->deref.child =
 210             &clone_deref_array(nir_deref_as_array(intr->variables[0]->deref.child),
 211                                &chan_intr->variables[0]->deref)->deref;
 212       }
 213
 214       if (intr->intrinsic == nir_intrinsic_interp_var_at_offset ||
 215           intr->intrinsic == nir_intrinsic_interp_var_at_sample)
 216          nir_src_copy(chan_intr->src, intr->src, &chan_intr->instr);
 217
 218       nir_builder_instr_insert(b, &chan_intr->instr);
 219
 220       loads[i] = &chan_intr->dest.ssa;
 221    }
 222
 223    nir_ssa_def_rewrite_uses(&intr->dest.ssa,
 224                             nir_src_for_ssa(nir_vec(b, loads,
 225                                                     intr->num_components)));
 226
 227    /* Remove the old load intrinsic */
 228    nir_instr_remove(&intr->instr);
 229 }
 230
 231 static void
 232 lower_store_output_to_scalar_early(nir_builder *b, nir_intrinsic_instr *intr,
 233                                    nir_variable *var,
 234                                    struct hash_table *split_outputs)
 235 {
 236    b->cursor = nir_before_instr(&intr->instr);
 237
 238    nir_ssa_def *value = nir_ssa_for_src(b, intr->src[0], intr->num_components);
 239
 240    nir_variable **chan_vars = get_channel_variables(split_outputs, var);
 241    for (unsigned i = 0; i < intr->num_components; i++) {
 242       if (!(nir_intrinsic_write_mask(intr) & (1 << i)))
 243          continue;
 244
 245       nir_variable *chan_var = chan_vars[var->data.location_frac + i];
 246       if (!chan_vars[var->data.location_frac + i]) {
 247          chan_var = nir_variable_clone(var, b->shader);
 248          chan_var->data.location_frac =  var->data.location_frac + i;
 249          chan_var->type = glsl_channel_type(chan_var->type);
 250
 251          chan_vars[var->data.location_frac + i] = chan_var;
 252
 253          nir_shader_add_variable(b->shader, chan_var);
 254       }
 255
 256       nir_intrinsic_instr *chan_intr =
 257          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
 258       chan_intr->num_components = 1;
 259
 260       nir_intrinsic_set_write_mask(chan_intr, 0x1);
 261
 262       chan_intr->variables[0] = nir_deref_var_create(chan_intr, chan_var);
 263       chan_intr->src[0] = nir_src_for_ssa(nir_channel(b, value, i));
 264
 265       if (intr->variables[0]->deref.child) {
 266          chan_intr->variables[0]->deref.child =
 267             &clone_deref_array(nir_deref_as_array(intr->variables[0]->deref.child),
 268                                &chan_intr->variables[0]->deref)->deref;
 269       }
 270
 271       nir_builder_instr_insert(b, &chan_intr->instr);
 272    }
 273
 274    /* Remove the old store intrinsic */
 275    nir_instr_remove(&intr->instr);
 276 }
 277
 278 /*
 279  * This function is intended to be called earlier than nir_lower_io_to_scalar()
 280  * i.e. before nir_lower_io() is called.
 281  */
 282 void
 283 nir_lower_io_to_scalar_early(nir_shader *shader, nir_variable_mode mask)
 284 {
 285    struct hash_table *split_inputs =
 286       _mesa_hash_table_create(NULL, _mesa_hash_pointer,
 287                               _mesa_key_pointer_equal);
 288    struct hash_table *split_outputs =
 289       _mesa_hash_table_create(NULL, _mesa_hash_pointer,
 290                               _mesa_key_pointer_equal);
 291
 292    nir_assert_lowered_derefs(shader, nir_lower_load_store_derefs | nir_lower_interp_derefs);
 293
 294    nir_foreach_function(function, shader) {
 295       if (function->impl) {
 296          nir_builder b;
 297          nir_builder_init(&b, function->impl);
 298
 299          nir_foreach_block(block, function->impl) {
 300             nir_foreach_instr_safe(instr, block) {
 301                if (instr->type != nir_instr_type_intrinsic)
 302                   continue;
 303
 304                nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 305
 306                if (intr->num_components == 1)
 307                   continue;
 308
 309                if (intr->intrinsic != nir_intrinsic_load_var &&
 310                    intr->intrinsic != nir_intrinsic_store_var &&
 311                    intr->intrinsic != nir_intrinsic_interp_var_at_centroid &&
 312                    intr->intrinsic != nir_intrinsic_interp_var_at_sample &&
 313                    intr->intrinsic != nir_intrinsic_interp_var_at_offset)
 314                   continue;
 315
 316                nir_variable *var = intr->variables[0]->var;
 317                nir_variable_mode mode = var->data.mode;
 318
 319                /* TODO: add patch support */
 320                if (var->data.patch)
 321                   continue;
 322
 323                /* TODO: add doubles support */
 324                if (glsl_type_is_64bit(glsl_without_array(var->type)))
 325                   continue;
 326
 327                if (var->data.location < VARYING_SLOT_VAR0 &&
 328                    var->data.location >= 0)
 329                   continue;
 330
 331                /* Don't bother splitting if we can't opt away any unused
 332                 * components.
 333                 */
 334                if (var->data.always_active_io)
 335                   continue;
 336
 337               /* Skip types we cannot split */
 338               if (glsl_type_is_matrix(glsl_without_array(var->type)) ||
 339                   glsl_type_is_struct(glsl_without_array(var->type)))
 340                  continue;
 341
 342                switch (intr->intrinsic) {
 343                case nir_intrinsic_interp_var_at_centroid:
 344                case nir_intrinsic_interp_var_at_sample:
 345                case nir_intrinsic_interp_var_at_offset:
 346                case nir_intrinsic_load_var:
 347                   if ((mask & nir_var_shader_in && mode == nir_var_shader_in) ||
 348                       (mask & nir_var_shader_out && mode == nir_var_shader_out))
 349                      lower_load_to_scalar_early(&b, intr, var, split_inputs,
 350                                                 split_outputs);
 351                   break;
 352                case nir_intrinsic_store_var:
 353                   if (mask & nir_var_shader_out &&
 354                       mode == nir_var_shader_out)
 355                      lower_store_output_to_scalar_early(&b, intr, var,
 356                                                         split_outputs);
 357                   break;
 358                default:
 359                   break;
 360                }
 361             }
 362          }
 363       }
 364    }
 365
 366    /* Remove old input from the shaders inputs list */
 367    struct hash_entry *entry;
 368    hash_table_foreach(split_inputs, entry) {
 369       nir_variable *var = (nir_variable *) entry->key;
 370       exec_node_remove(&var->node);
 371
 372       free(entry->data);
 373    }
 374
 375    /* Remove old output from the shaders outputs list */
 376    hash_table_foreach(split_outputs, entry) {
 377       nir_variable *var = (nir_variable *) entry->key;
 378       exec_node_remove(&var->node);
 379
 380       free(entry->data);
 381    }
 382
 383    _mesa_hash_table_destroy(split_inputs, NULL);
 384    _mesa_hash_table_destroy(split_outputs, NULL);
 385 }