src/compiler/nir/nir_lower_io.c

   1 /*
   2  * Copyright © 2014 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  * Authors:
  24  *    Connor Abbott (cwabbott0@gmail.com)
  25  *    Jason Ekstrand (jason@jlekstrand.net)
  26  *
  27  */
  28
  29 /*
  30  * This lowering pass converts references to input/output variables with
  31  * loads/stores to actual input/output intrinsics.
  32  */
  33
  34 #include "nir.h"
  35 #include "nir_builder.h"
  36
  37 struct lower_io_state {
  38    nir_builder builder;
  39    int (*type_size)(const struct glsl_type *type);
  40    nir_variable_mode modes;
  41    nir_lower_io_options options;
  42 };
  43
  44 void
  45 nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
  46                          int (*type_size)(const struct glsl_type *))
  47 {
  48    unsigned location = 0;
  49
  50    nir_foreach_variable(var, var_list) {
  51       /*
  52        * UBOs have their own address spaces, so don't count them towards the
  53        * number of global uniforms
  54        */
  55       if ((var->data.mode == nir_var_uniform || var->data.mode == nir_var_shader_storage) &&
  56           var->interface_type != NULL)
  57          continue;
  58
  59       var->data.driver_location = location;
  60       location += type_size(var->type);
  61    }
  62
  63    *size = location;
  64 }
  65
  66 /**
  67  * Return true if the given variable is a per-vertex input/output array.
  68  * (such as geometry shader inputs).
  69  */
  70 bool
  71 nir_is_per_vertex_io(nir_variable *var, gl_shader_stage stage)
  72 {
  73    if (var->data.patch || !glsl_type_is_array(var->type))
  74       return false;
  75
  76    if (var->data.mode == nir_var_shader_in)
  77       return stage == MESA_SHADER_GEOMETRY ||
  78              stage == MESA_SHADER_TESS_CTRL ||
  79              stage == MESA_SHADER_TESS_EVAL;
  80
  81    if (var->data.mode == nir_var_shader_out)
  82       return stage == MESA_SHADER_TESS_CTRL;
  83
  84    return false;
  85 }
  86
  87 static nir_ssa_def *
  88 get_io_offset(nir_builder *b, nir_deref_var *deref,
  89               nir_ssa_def **vertex_index,
  90               int (*type_size)(const struct glsl_type *),
  91               unsigned *component)
  92 {
  93    nir_deref *tail = &deref->deref;
  94
  95    /* For per-vertex input arrays (i.e. geometry shader inputs), keep the
  96     * outermost array index separate.  Process the rest normally.
  97     */
  98    if (vertex_index != NULL) {
  99       tail = tail->child;
 100       nir_deref_array *deref_array = nir_deref_as_array(tail);
 101
 102       nir_ssa_def *vtx = nir_imm_int(b, deref_array->base_offset);
 103       if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
 104          vtx = nir_iadd(b, vtx, nir_ssa_for_src(b, deref_array->indirect, 1));
 105       }
 106       *vertex_index = vtx;
 107    }
 108
 109    if (deref->var->data.compact) {
 110       assert(tail->child->deref_type == nir_deref_type_array);
 111       assert(glsl_type_is_scalar(glsl_without_array(deref->var->type)));
 112       nir_deref_array *deref_array = nir_deref_as_array(tail->child);
 113       /* We always lower indirect dereferences for "compact" array vars. */
 114       assert(deref_array->deref_array_type == nir_deref_array_type_direct);
 115
 116       const unsigned total_offset = *component + deref_array->base_offset;
 117       const unsigned slot_offset = total_offset / 4;
 118       *component = total_offset % 4;
 119       return nir_imm_int(b, type_size(glsl_vec4_type()) * slot_offset);
 120    }
 121
 122    /* Just emit code and let constant-folding go to town */
 123    nir_ssa_def *offset = nir_imm_int(b, 0);
 124
 125    while (tail->child != NULL) {
 126       const struct glsl_type *parent_type = tail->type;
 127       tail = tail->child;
 128
 129       if (tail->deref_type == nir_deref_type_array) {
 130          nir_deref_array *deref_array = nir_deref_as_array(tail);
 131          unsigned size = type_size(tail->type);
 132
 133          offset = nir_iadd(b, offset,
 134                            nir_imm_int(b, size * deref_array->base_offset));
 135
 136          if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
 137             nir_ssa_def *mul =
 138                nir_imul(b, nir_imm_int(b, size),
 139                         nir_ssa_for_src(b, deref_array->indirect, 1));
 140
 141             offset = nir_iadd(b, offset, mul);
 142          }
 143       } else if (tail->deref_type == nir_deref_type_struct) {
 144          nir_deref_struct *deref_struct = nir_deref_as_struct(tail);
 145
 146          unsigned field_offset = 0;
 147          for (unsigned i = 0; i < deref_struct->index; i++) {
 148             field_offset += type_size(glsl_get_struct_field(parent_type, i));
 149          }
 150          offset = nir_iadd(b, offset, nir_imm_int(b, field_offset));
 151       }
 152    }
 153
 154    return offset;
 155 }
 156
 157 static nir_intrinsic_instr *
 158 lower_load(nir_intrinsic_instr *intrin, struct lower_io_state *state,
 159            nir_ssa_def *vertex_index, nir_ssa_def *offset,
 160            unsigned component)
 161 {
 162    const nir_shader *nir = state->builder.shader;
 163    nir_variable *var = intrin->variables[0]->var;
 164    nir_variable_mode mode = var->data.mode;
 165    nir_ssa_def *barycentric = NULL;
 166
 167    nir_intrinsic_op op;
 168    switch (mode) {
 169    case nir_var_shader_in:
 170       if (nir->stage == MESA_SHADER_FRAGMENT &&
 171           nir->options->use_interpolated_input_intrinsics &&
 172           var->data.interpolation != INTERP_MODE_FLAT) {
 173          assert(vertex_index == NULL);
 174
 175          nir_intrinsic_op bary_op;
 176          if (var->data.sample ||
 177              (state->options & nir_lower_io_force_sample_interpolation))
 178             bary_op = nir_intrinsic_load_barycentric_sample;
 179          else if (var->data.centroid)
 180             bary_op = nir_intrinsic_load_barycentric_centroid;
 181          else
 182             bary_op = nir_intrinsic_load_barycentric_pixel;
 183
 184          barycentric = nir_load_barycentric(&state->builder, bary_op,
 185                                             var->data.interpolation);
 186          op = nir_intrinsic_load_interpolated_input;
 187       } else {
 188          op = vertex_index ? nir_intrinsic_load_per_vertex_input :
 189                              nir_intrinsic_load_input;
 190       }
 191       break;
 192    case nir_var_shader_out:
 193       op = vertex_index ? nir_intrinsic_load_per_vertex_output :
 194                           nir_intrinsic_load_output;
 195       break;
 196    case nir_var_uniform:
 197       op = nir_intrinsic_load_uniform;
 198       break;
 199    case nir_var_shared:
 200       op = nir_intrinsic_load_shared;
 201       break;
 202    default:
 203       unreachable("Unknown variable mode");
 204    }
 205
 206    nir_intrinsic_instr *load =
 207       nir_intrinsic_instr_create(state->builder.shader, op);
 208    load->num_components = intrin->num_components;
 209
 210    nir_intrinsic_set_base(load, var->data.driver_location);
 211    if (mode == nir_var_shader_in || mode == nir_var_shader_out)
 212       nir_intrinsic_set_component(load, component);
 213
 214    if (load->intrinsic == nir_intrinsic_load_uniform)
 215       nir_intrinsic_set_range(load, state->type_size(var->type));
 216
 217    if (vertex_index) {
 218       load->src[0] = nir_src_for_ssa(vertex_index);
 219       load->src[1] = nir_src_for_ssa(offset);
 220    } else if (barycentric) {
 221       load->src[0] = nir_src_for_ssa(barycentric);
 222       load->src[1] = nir_src_for_ssa(offset);
 223    } else {
 224       load->src[0] = nir_src_for_ssa(offset);
 225    }
 226
 227    return load;
 228 }
 229
 230 static nir_intrinsic_instr *
 231 lower_store(nir_intrinsic_instr *intrin, struct lower_io_state *state,
 232             nir_ssa_def *vertex_index, nir_ssa_def *offset,
 233             unsigned component)
 234 {
 235    nir_variable *var = intrin->variables[0]->var;
 236    nir_variable_mode mode = var->data.mode;
 237
 238    nir_intrinsic_op op;
 239    if (mode == nir_var_shared) {
 240       op = nir_intrinsic_store_shared;
 241    } else {
 242       assert(mode == nir_var_shader_out);
 243       op = vertex_index ? nir_intrinsic_store_per_vertex_output :
 244                           nir_intrinsic_store_output;
 245    }
 246
 247    nir_intrinsic_instr *store =
 248       nir_intrinsic_instr_create(state->builder.shader, op);
 249    store->num_components = intrin->num_components;
 250
 251    nir_src_copy(&store->src[0], &intrin->src[0], store);
 252
 253    nir_intrinsic_set_base(store, var->data.driver_location);
 254
 255    if (mode == nir_var_shader_out)
 256       nir_intrinsic_set_component(store, component);
 257
 258    nir_intrinsic_set_write_mask(store, nir_intrinsic_write_mask(intrin));
 259
 260    if (vertex_index)
 261       store->src[1] = nir_src_for_ssa(vertex_index);
 262
 263    store->src[vertex_index ? 2 : 1] = nir_src_for_ssa(offset);
 264
 265    return store;
 266 }
 267
 268 static nir_intrinsic_instr *
 269 lower_atomic(nir_intrinsic_instr *intrin, struct lower_io_state *state,
 270              nir_ssa_def *offset)
 271 {
 272    nir_variable *var = intrin->variables[0]->var;
 273
 274    assert(var->data.mode == nir_var_shared);
 275
 276    nir_intrinsic_op op;
 277    switch (intrin->intrinsic) {
 278 #define OP(O) case nir_intrinsic_var_##O: op = nir_intrinsic_shared_##O; break;
 279    OP(atomic_exchange)
 280    OP(atomic_comp_swap)
 281    OP(atomic_add)
 282    OP(atomic_imin)
 283    OP(atomic_umin)
 284    OP(atomic_imax)
 285    OP(atomic_umax)
 286    OP(atomic_and)
 287    OP(atomic_or)
 288    OP(atomic_xor)
 289 #undef OP
 290    default:
 291       unreachable("Invalid atomic");
 292    }
 293
 294    nir_intrinsic_instr *atomic =
 295       nir_intrinsic_instr_create(state->builder.shader, op);
 296
 297    nir_intrinsic_set_base(atomic, var->data.driver_location);
 298
 299    atomic->src[0] = nir_src_for_ssa(offset);
 300    for (unsigned i = 0; i < nir_intrinsic_infos[intrin->intrinsic].num_srcs; i++) {
 301       nir_src_copy(&atomic->src[i+1], &intrin->src[i], atomic);
 302    }
 303
 304    return atomic;
 305 }
 306
 307 static nir_intrinsic_instr *
 308 lower_interpolate_at(nir_intrinsic_instr *intrin, struct lower_io_state *state,
 309                      nir_ssa_def *offset, unsigned component)
 310 {
 311    nir_variable *var = intrin->variables[0]->var;
 312
 313    assert(var->data.mode == nir_var_shader_in);
 314
 315    /* Ignore interpolateAt() for flat variables - flat is flat. */
 316    if (var->data.interpolation == INTERP_MODE_FLAT)
 317       return lower_load(intrin, state, NULL, offset, component);
 318
 319    nir_intrinsic_op bary_op;
 320    switch (intrin->intrinsic) {
 321    case nir_intrinsic_interp_var_at_centroid:
 322       bary_op = (state->options & nir_lower_io_force_sample_interpolation) ?
 323                 nir_intrinsic_load_barycentric_sample :
 324                 nir_intrinsic_load_barycentric_centroid;
 325       break;
 326    case nir_intrinsic_interp_var_at_sample:
 327       bary_op = nir_intrinsic_load_barycentric_at_sample;
 328       break;
 329    case nir_intrinsic_interp_var_at_offset:
 330       bary_op = nir_intrinsic_load_barycentric_at_offset;
 331       break;
 332    default:
 333       unreachable("Bogus interpolateAt() intrinsic.");
 334    }
 335
 336    nir_intrinsic_instr *bary_setup =
 337       nir_intrinsic_instr_create(state->builder.shader, bary_op);
 338
 339    nir_ssa_dest_init(&bary_setup->instr, &bary_setup->dest, 2, 32, NULL);
 340    nir_intrinsic_set_interp_mode(bary_setup, var->data.interpolation);
 341
 342    if (intrin->intrinsic != nir_intrinsic_interp_var_at_centroid)
 343       nir_src_copy(&bary_setup->src[0], &intrin->src[0], bary_setup);
 344
 345    nir_builder_instr_insert(&state->builder, &bary_setup->instr);
 346
 347    nir_intrinsic_instr *load =
 348       nir_intrinsic_instr_create(state->builder.shader,
 349                                  nir_intrinsic_load_interpolated_input);
 350    load->num_components = intrin->num_components;
 351
 352    nir_intrinsic_set_base(load, var->data.driver_location);
 353    nir_intrinsic_set_component(load, component);
 354
 355    load->src[0] = nir_src_for_ssa(&bary_setup->dest.ssa);
 356    load->src[1] = nir_src_for_ssa(offset);
 357
 358    return load;
 359 }
 360
 361 static bool
 362 nir_lower_io_block(nir_block *block,
 363                    struct lower_io_state *state)
 364 {
 365    nir_builder *b = &state->builder;
 366    const nir_shader_compiler_options *options = b->shader->options;
 367
 368    nir_foreach_instr_safe(instr, block) {
 369       if (instr->type != nir_instr_type_intrinsic)
 370          continue;
 371
 372       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
 373
 374       switch (intrin->intrinsic) {
 375       case nir_intrinsic_load_var:
 376       case nir_intrinsic_store_var:
 377       case nir_intrinsic_var_atomic_add:
 378       case nir_intrinsic_var_atomic_imin:
 379       case nir_intrinsic_var_atomic_umin:
 380       case nir_intrinsic_var_atomic_imax:
 381       case nir_intrinsic_var_atomic_umax:
 382       case nir_intrinsic_var_atomic_and:
 383       case nir_intrinsic_var_atomic_or:
 384       case nir_intrinsic_var_atomic_xor:
 385       case nir_intrinsic_var_atomic_exchange:
 386       case nir_intrinsic_var_atomic_comp_swap:
 387          /* We can lower the io for this nir instrinsic */
 388          break;
 389       case nir_intrinsic_interp_var_at_centroid:
 390       case nir_intrinsic_interp_var_at_sample:
 391       case nir_intrinsic_interp_var_at_offset:
 392          /* We can optionally lower these to load_interpolated_input */
 393          if (options->use_interpolated_input_intrinsics)
 394             break;
 395       default:
 396          /* We can't lower the io for this nir instrinsic, so skip it */
 397          continue;
 398       }
 399
 400       nir_variable *var = intrin->variables[0]->var;
 401       nir_variable_mode mode = var->data.mode;
 402
 403       if ((state->modes & mode) == 0)
 404          continue;
 405
 406       if (mode != nir_var_shader_in &&
 407           mode != nir_var_shader_out &&
 408           mode != nir_var_shared &&
 409           mode != nir_var_uniform)
 410          continue;
 411
 412       b->cursor = nir_before_instr(instr);
 413
 414       const bool per_vertex = nir_is_per_vertex_io(var, b->shader->stage);
 415
 416       nir_ssa_def *offset;
 417       nir_ssa_def *vertex_index = NULL;
 418       unsigned component_offset = var->data.location_frac;
 419
 420       offset = get_io_offset(b, intrin->variables[0],
 421                              per_vertex ? &vertex_index : NULL,
 422                              state->type_size, &component_offset);
 423
 424       nir_intrinsic_instr *replacement;
 425
 426       switch (intrin->intrinsic) {
 427       case nir_intrinsic_load_var:
 428          replacement = lower_load(intrin, state, vertex_index, offset,
 429                                   component_offset);
 430          break;
 431
 432       case nir_intrinsic_store_var:
 433          replacement = lower_store(intrin, state, vertex_index, offset,
 434                                    component_offset);
 435          break;
 436
 437       case nir_intrinsic_var_atomic_add:
 438       case nir_intrinsic_var_atomic_imin:
 439       case nir_intrinsic_var_atomic_umin:
 440       case nir_intrinsic_var_atomic_imax:
 441       case nir_intrinsic_var_atomic_umax:
 442       case nir_intrinsic_var_atomic_and:
 443       case nir_intrinsic_var_atomic_or:
 444       case nir_intrinsic_var_atomic_xor:
 445       case nir_intrinsic_var_atomic_exchange:
 446       case nir_intrinsic_var_atomic_comp_swap:
 447          assert(vertex_index == NULL);
 448          replacement = lower_atomic(intrin, state, offset);
 449          break;
 450
 451       case nir_intrinsic_interp_var_at_centroid:
 452       case nir_intrinsic_interp_var_at_sample:
 453       case nir_intrinsic_interp_var_at_offset:
 454          assert(vertex_index == NULL);
 455          replacement = lower_interpolate_at(intrin, state, offset,
 456                                             component_offset);
 457          break;
 458
 459       default:
 460          continue;
 461       }
 462
 463       if (nir_intrinsic_infos[intrin->intrinsic].has_dest) {
 464          if (intrin->dest.is_ssa) {
 465             nir_ssa_dest_init(&replacement->instr, &replacement->dest,
 466                               intrin->dest.ssa.num_components,
 467                               intrin->dest.ssa.bit_size, NULL);
 468             nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
 469                                      nir_src_for_ssa(&replacement->dest.ssa));
 470          } else {
 471             nir_dest_copy(&replacement->dest, &intrin->dest, &intrin->instr);
 472          }
 473       }
 474
 475       nir_instr_insert_before(&intrin->instr, &replacement->instr);
 476       nir_instr_remove(&intrin->instr);
 477    }
 478
 479    return true;
 480 }
 481
 482 static void
 483 nir_lower_io_impl(nir_function_impl *impl,
 484                   nir_variable_mode modes,
 485                   int (*type_size)(const struct glsl_type *),
 486                   nir_lower_io_options options)
 487 {
 488    struct lower_io_state state;
 489
 490    nir_builder_init(&state.builder, impl);
 491    state.modes = modes;
 492    state.type_size = type_size;
 493    state.options = options;
 494
 495    nir_foreach_block(block, impl) {
 496       nir_lower_io_block(block, &state);
 497    }
 498
 499    nir_metadata_preserve(impl, nir_metadata_block_index |
 500                                nir_metadata_dominance);
 501 }
 502
 503 void
 504 nir_lower_io(nir_shader *shader, nir_variable_mode modes,
 505              int (*type_size)(const struct glsl_type *),
 506              nir_lower_io_options options)
 507 {
 508    nir_foreach_function(function, shader) {
 509       if (function->impl) {
 510          nir_lower_io_impl(function->impl, modes, type_size, options);
 511       }
 512    }
 513 }
 514
 515 /**
 516  * Return the offset soruce for a load/store intrinsic.
 517  */
 518 nir_src *
 519 nir_get_io_offset_src(nir_intrinsic_instr *instr)
 520 {
 521    switch (instr->intrinsic) {
 522    case nir_intrinsic_load_input:
 523    case nir_intrinsic_load_output:
 524    case nir_intrinsic_load_uniform:
 525       return &instr->src[0];
 526    case nir_intrinsic_load_ubo:
 527    case nir_intrinsic_load_ssbo:
 528    case nir_intrinsic_load_per_vertex_input:
 529    case nir_intrinsic_load_per_vertex_output:
 530    case nir_intrinsic_load_interpolated_input:
 531    case nir_intrinsic_store_output:
 532       return &instr->src[1];
 533    case nir_intrinsic_store_ssbo:
 534    case nir_intrinsic_store_per_vertex_output:
 535       return &instr->src[2];
 536    default:
 537       return NULL;
 538    }
 539 }
 540
 541 /**
 542  * Return the vertex index source for a load/store per_vertex intrinsic.
 543  */
 544 nir_src *
 545 nir_get_io_vertex_index_src(nir_intrinsic_instr *instr)
 546 {
 547    switch (instr->intrinsic) {
 548    case nir_intrinsic_load_per_vertex_input:
 549    case nir_intrinsic_load_per_vertex_output:
 550       return &instr->src[0];
 551    case nir_intrinsic_store_per_vertex_output:
 552       return &instr->src[1];
 553    default:
 554       return NULL;
 555    }
 556 }