src/compiler/nir/nir_search.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  *    Jason Ekstrand (jason@jlekstrand.net)
  25  *
  26  */
  27
  28 #include <inttypes.h>
  29 #include "nir_search.h"
  30
  31 struct match_state {
  32    bool inexact_match;
  33    bool has_exact_alu;
  34    unsigned variables_seen;
  35    nir_alu_src variables[NIR_SEARCH_MAX_VARIABLES];
  36 };
  37
  38 static bool
  39 match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
  40                  unsigned num_components, const uint8_t *swizzle,
  41                  struct match_state *state);
  42
  43 static const uint8_t identity_swizzle[] = { 0, 1, 2, 3 };
  44
  45 static bool alu_instr_is_bool(nir_alu_instr *instr);
  46
  47 static bool
  48 src_is_bool(nir_src src)
  49 {
  50    if (!src.is_ssa)
  51       return false;
  52    if (src.ssa->parent_instr->type != nir_instr_type_alu)
  53       return false;
  54    return alu_instr_is_bool(nir_instr_as_alu(src.ssa->parent_instr));
  55 }
  56
  57 static bool
  58 alu_instr_is_bool(nir_alu_instr *instr)
  59 {
  60    switch (instr->op) {
  61    case nir_op_iand:
  62    case nir_op_ior:
  63    case nir_op_ixor:
  64       return src_is_bool(instr->src[0].src) && src_is_bool(instr->src[1].src);
  65    case nir_op_inot:
  66       return src_is_bool(instr->src[0].src);
  67    default:
  68       return (nir_alu_type_get_base_type(nir_op_infos[instr->op].output_type)
  69              == nir_type_bool);
  70    }
  71 }
  72
  73 static bool
  74 match_value(const nir_search_value *value, nir_alu_instr *instr, unsigned src,
  75             unsigned num_components, const uint8_t *swizzle,
  76             struct match_state *state)
  77 {
  78    uint8_t new_swizzle[4];
  79
  80    /* If the source is an explicitly sized source, then we need to reset
  81     * both the number of components and the swizzle.
  82     */
  83    if (nir_op_infos[instr->op].input_sizes[src] != 0) {
  84       num_components = nir_op_infos[instr->op].input_sizes[src];
  85       swizzle = identity_swizzle;
  86    }
  87
  88    for (unsigned i = 0; i < num_components; ++i)
  89       new_swizzle[i] = instr->src[src].swizzle[swizzle[i]];
  90
  91    switch (value->type) {
  92    case nir_search_value_expression:
  93       if (!instr->src[src].src.is_ssa)
  94          return false;
  95
  96       if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_alu)
  97          return false;
  98
  99       return match_expression(nir_search_value_as_expression(value),
 100                               nir_instr_as_alu(instr->src[src].src.ssa->parent_instr),
 101                               num_components, new_swizzle, state);
 102
 103    case nir_search_value_variable: {
 104       nir_search_variable *var = nir_search_value_as_variable(value);
 105       assert(var->variable < NIR_SEARCH_MAX_VARIABLES);
 106
 107       if (state->variables_seen & (1 << var->variable)) {
 108          if (!nir_srcs_equal(state->variables[var->variable].src,
 109                              instr->src[src].src))
 110             return false;
 111
 112          assert(!instr->src[src].abs && !instr->src[src].negate);
 113
 114          for (unsigned i = 0; i < num_components; ++i) {
 115             if (state->variables[var->variable].swizzle[i] != new_swizzle[i])
 116                return false;
 117          }
 118
 119          return true;
 120       } else {
 121          if (var->is_constant &&
 122              instr->src[src].src.ssa->parent_instr->type != nir_instr_type_load_const)
 123             return false;
 124
 125          if (var->type != nir_type_invalid) {
 126             if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_alu)
 127                return false;
 128
 129             nir_alu_instr *src_alu =
 130                nir_instr_as_alu(instr->src[src].src.ssa->parent_instr);
 131
 132             if (nir_alu_type_get_base_type(nir_op_infos[src_alu->op].output_type) !=
 133                 var->type &&
 134                 !(nir_alu_type_get_base_type(var->type) == nir_type_bool &&
 135                   alu_instr_is_bool(src_alu)))
 136                return false;
 137          }
 138
 139          state->variables_seen |= (1 << var->variable);
 140          state->variables[var->variable].src = instr->src[src].src;
 141          state->variables[var->variable].abs = false;
 142          state->variables[var->variable].negate = false;
 143
 144          for (unsigned i = 0; i < 4; ++i) {
 145             if (i < num_components)
 146                state->variables[var->variable].swizzle[i] = new_swizzle[i];
 147             else
 148                state->variables[var->variable].swizzle[i] = 0;
 149          }
 150
 151          return true;
 152       }
 153    }
 154
 155    case nir_search_value_constant: {
 156       nir_search_constant *const_val = nir_search_value_as_constant(value);
 157
 158       if (!instr->src[src].src.is_ssa)
 159          return false;
 160
 161       if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_load_const)
 162          return false;
 163
 164       nir_load_const_instr *load =
 165          nir_instr_as_load_const(instr->src[src].src.ssa->parent_instr);
 166
 167       switch (const_val->type) {
 168       case nir_type_float:
 169          for (unsigned i = 0; i < num_components; ++i) {
 170             double val;
 171             switch (load->def.bit_size) {
 172             case 32:
 173                val = load->value.f32[new_swizzle[i]];
 174                break;
 175             case 64:
 176                val = load->value.f64[new_swizzle[i]];
 177                break;
 178             default:
 179                unreachable("unknown bit size");
 180             }
 181
 182             if (val != const_val->data.d)
 183                return false;
 184          }
 185          return true;
 186
 187       case nir_type_int:
 188          for (unsigned i = 0; i < num_components; ++i) {
 189             int64_t val;
 190             switch (load->def.bit_size) {
 191             case 32:
 192                val = load->value.i32[new_swizzle[i]];
 193                break;
 194             case 64:
 195                val = load->value.i64[new_swizzle[i]];
 196                break;
 197             default:
 198                unreachable("unknown bit size");
 199             }
 200
 201             if (val != const_val->data.i)
 202                return false;
 203          }
 204          return true;
 205
 206       case nir_type_uint:
 207       case nir_type_bool32:
 208          for (unsigned i = 0; i < num_components; ++i) {
 209             uint64_t val;
 210             switch (load->def.bit_size) {
 211             case 32:
 212                val = load->value.u32[new_swizzle[i]];
 213                break;
 214             case 64:
 215                val = load->value.u64[new_swizzle[i]];
 216                break;
 217             default:
 218                unreachable("unknown bit size");
 219             }
 220
 221             if (val != const_val->data.u)
 222                return false;
 223          }
 224          return true;
 225
 226       default:
 227          unreachable("Invalid alu source type");
 228       }
 229    }
 230
 231    default:
 232       unreachable("Invalid search value type");
 233    }
 234 }
 235
 236 static bool
 237 match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
 238                  unsigned num_components, const uint8_t *swizzle,
 239                  struct match_state *state)
 240 {
 241    if (instr->op != expr->opcode)
 242       return false;
 243
 244    assert(instr->dest.dest.is_ssa);
 245
 246    state->inexact_match = expr->inexact || state->inexact_match;
 247    state->has_exact_alu = instr->exact || state->has_exact_alu;
 248    if (state->inexact_match && state->has_exact_alu)
 249       return false;
 250
 251    assert(!instr->dest.saturate);
 252    assert(nir_op_infos[instr->op].num_inputs > 0);
 253
 254    /* If we have an explicitly sized destination, we can only handle the
 255     * identity swizzle.  While dot(vec3(a, b, c).zxy) is a valid
 256     * expression, we don't have the information right now to propagate that
 257     * swizzle through.  We can only properly propagate swizzles if the
 258     * instruction is vectorized.
 259     */
 260    if (nir_op_infos[instr->op].output_size != 0) {
 261       for (unsigned i = 0; i < num_components; i++) {
 262          if (swizzle[i] != i)
 263             return false;
 264       }
 265    }
 266
 267    /* Stash off the current variables_seen bitmask.  This way we can
 268     * restore it prior to matching in the commutative case below.
 269     */
 270    unsigned variables_seen_stash = state->variables_seen;
 271
 272    bool matched = true;
 273    for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
 274       if (!match_value(expr->srcs[i], instr, i, num_components,
 275                        swizzle, state)) {
 276          matched = false;
 277          break;
 278       }
 279    }
 280
 281    if (matched)
 282       return true;
 283
 284    if (nir_op_infos[instr->op].algebraic_properties & NIR_OP_IS_COMMUTATIVE) {
 285       assert(nir_op_infos[instr->op].num_inputs == 2);
 286
 287       /* Restore the variables_seen bitmask.  If we don't do this, then we
 288        * could end up with an erroneous failure due to variables found in the
 289        * first match attempt above not matching those in the second.
 290        */
 291       state->variables_seen = variables_seen_stash;
 292
 293       if (!match_value(expr->srcs[0], instr, 1, num_components,
 294                        swizzle, state))
 295          return false;
 296
 297       return match_value(expr->srcs[1], instr, 0, num_components,
 298                          swizzle, state);
 299    } else {
 300       return false;
 301    }
 302 }
 303
 304 typedef struct bitsize_tree {
 305    unsigned num_srcs;
 306    struct bitsize_tree *srcs[4];
 307
 308    unsigned common_size;
 309    bool is_src_sized[4];
 310    bool is_dest_sized;
 311
 312    unsigned dest_size;
 313    unsigned src_size[4];
 314 } bitsize_tree;
 315
 316 static bitsize_tree *
 317 build_bitsize_tree(void *mem_ctx, struct match_state *state,
 318                    const nir_search_value *value)
 319 {
 320    bitsize_tree *tree = ralloc(mem_ctx, bitsize_tree);
 321
 322    switch (value->type) {
 323    case nir_search_value_expression: {
 324       nir_search_expression *expr = nir_search_value_as_expression(value);
 325       nir_op_info info = nir_op_infos[expr->opcode];
 326       tree->num_srcs = info.num_inputs;
 327       tree->common_size = 0;
 328       for (unsigned i = 0; i < info.num_inputs; i++) {
 329          tree->is_src_sized[i] = !!nir_alu_type_get_type_size(info.input_types[i]);
 330          if (tree->is_src_sized[i])
 331             tree->src_size[i] = nir_alu_type_get_type_size(info.input_types[i]);
 332          tree->srcs[i] = build_bitsize_tree(mem_ctx, state, expr->srcs[i]);
 333       }
 334       tree->is_dest_sized = !!nir_alu_type_get_type_size(info.output_type);
 335       if (tree->is_dest_sized)
 336          tree->dest_size = nir_alu_type_get_type_size(info.output_type);
 337       break;
 338    }
 339
 340    case nir_search_value_variable: {
 341       nir_search_variable *var = nir_search_value_as_variable(value);
 342       tree->num_srcs = 0;
 343       tree->is_dest_sized = true;
 344       tree->dest_size = nir_src_bit_size(state->variables[var->variable].src);
 345       break;
 346    }
 347
 348    case nir_search_value_constant: {
 349       tree->num_srcs = 0;
 350       tree->is_dest_sized = false;
 351       tree->common_size = 0;
 352       break;
 353    }
 354    }
 355
 356    return tree;
 357 }
 358
 359 static unsigned
 360 bitsize_tree_filter_up(bitsize_tree *tree)
 361 {
 362    for (unsigned i = 0; i < tree->num_srcs; i++) {
 363       unsigned src_size = bitsize_tree_filter_up(tree->srcs[i]);
 364       if (src_size == 0)
 365          continue;
 366
 367       if (tree->is_src_sized[i]) {
 368          assert(src_size == tree->src_size[i]);
 369       } else if (tree->common_size != 0) {
 370          assert(src_size == tree->common_size);
 371          tree->src_size[i] = src_size;
 372       } else {
 373          tree->common_size = src_size;
 374          tree->src_size[i] = src_size;
 375       }
 376    }
 377
 378    if (tree->num_srcs && tree->common_size) {
 379       if (tree->dest_size == 0)
 380          tree->dest_size = tree->common_size;
 381       else if (!tree->is_dest_sized)
 382          assert(tree->dest_size == tree->common_size);
 383
 384       for (unsigned i = 0; i < tree->num_srcs; i++) {
 385          if (!tree->src_size[i])
 386             tree->src_size[i] = tree->common_size;
 387       }
 388    }
 389
 390    return tree->dest_size;
 391 }
 392
 393 static void
 394 bitsize_tree_filter_down(bitsize_tree *tree, unsigned size)
 395 {
 396    if (tree->dest_size)
 397       assert(tree->dest_size == size);
 398    else
 399       tree->dest_size = size;
 400
 401    if (!tree->is_dest_sized) {
 402       if (tree->common_size)
 403          assert(tree->common_size == size);
 404       else
 405          tree->common_size = size;
 406    }
 407
 408    for (unsigned i = 0; i < tree->num_srcs; i++) {
 409       if (!tree->src_size[i]) {
 410          assert(tree->common_size);
 411          tree->src_size[i] = tree->common_size;
 412       }
 413       bitsize_tree_filter_down(tree->srcs[i], tree->src_size[i]);
 414    }
 415 }
 416
 417 static nir_alu_src
 418 construct_value(const nir_search_value *value,
 419                 unsigned num_components, bitsize_tree *bitsize,
 420                 struct match_state *state,
 421                 nir_instr *instr, void *mem_ctx)
 422 {
 423    switch (value->type) {
 424    case nir_search_value_expression: {
 425       const nir_search_expression *expr = nir_search_value_as_expression(value);
 426
 427       if (nir_op_infos[expr->opcode].output_size != 0)
 428          num_components = nir_op_infos[expr->opcode].output_size;
 429
 430       nir_alu_instr *alu = nir_alu_instr_create(mem_ctx, expr->opcode);
 431       nir_ssa_dest_init(&alu->instr, &alu->dest.dest, num_components,
 432                         bitsize->dest_size, NULL);
 433       alu->dest.write_mask = (1 << num_components) - 1;
 434       alu->dest.saturate = false;
 435
 436       /* We have no way of knowing what values in a given search expression
 437        * map to a particular replacement value.  Therefore, if the
 438        * expression we are replacing has any exact values, the entire
 439        * replacement should be exact.
 440        */
 441       alu->exact = state->has_exact_alu;
 442
 443       for (unsigned i = 0; i < nir_op_infos[expr->opcode].num_inputs; i++) {
 444          /* If the source is an explicitly sized source, then we need to reset
 445           * the number of components to match.
 446           */
 447          if (nir_op_infos[alu->op].input_sizes[i] != 0)
 448             num_components = nir_op_infos[alu->op].input_sizes[i];
 449
 450          alu->src[i] = construct_value(expr->srcs[i],
 451                                        num_components, bitsize->srcs[i],
 452                                        state, instr, mem_ctx);
 453       }
 454
 455       nir_instr_insert_before(instr, &alu->instr);
 456
 457       nir_alu_src val;
 458       val.src = nir_src_for_ssa(&alu->dest.dest.ssa);
 459       val.negate = false;
 460       val.abs = false,
 461       memcpy(val.swizzle, identity_swizzle, sizeof val.swizzle);
 462
 463       return val;
 464    }
 465
 466    case nir_search_value_variable: {
 467       const nir_search_variable *var = nir_search_value_as_variable(value);
 468       assert(state->variables_seen & (1 << var->variable));
 469
 470       nir_alu_src val = { NIR_SRC_INIT };
 471       nir_alu_src_copy(&val, &state->variables[var->variable], mem_ctx);
 472
 473       assert(!var->is_constant);
 474
 475       return val;
 476    }
 477
 478    case nir_search_value_constant: {
 479       const nir_search_constant *c = nir_search_value_as_constant(value);
 480       nir_load_const_instr *load =
 481          nir_load_const_instr_create(mem_ctx, 1, bitsize->dest_size);
 482
 483       switch (c->type) {
 484       case nir_type_float:
 485          load->def.name = ralloc_asprintf(load, "%f", c->data.d);
 486          switch (bitsize->dest_size) {
 487          case 32:
 488             load->value.f32[0] = c->data.d;
 489             break;
 490          case 64:
 491             load->value.f64[0] = c->data.d;
 492             break;
 493          default:
 494             unreachable("unknown bit size");
 495          }
 496          break;
 497
 498       case nir_type_int:
 499          load->def.name = ralloc_asprintf(load, "%" PRIi64, c->data.i);
 500          switch (bitsize->dest_size) {
 501          case 32:
 502             load->value.i32[0] = c->data.i;
 503             break;
 504          case 64:
 505             load->value.i64[0] = c->data.i;
 506             break;
 507          default:
 508             unreachable("unknown bit size");
 509          }
 510          break;
 511
 512       case nir_type_uint:
 513          load->def.name = ralloc_asprintf(load, "%" PRIu64, c->data.u);
 514          switch (bitsize->dest_size) {
 515          case 32:
 516             load->value.u32[0] = c->data.u;
 517             break;
 518          case 64:
 519             load->value.u64[0] = c->data.u;
 520             break;
 521          default:
 522             unreachable("unknown bit size");
 523          }
 524
 525       case nir_type_bool32:
 526          load->value.u32[0] = c->data.u;
 527          break;
 528       default:
 529          unreachable("Invalid alu source type");
 530       }
 531
 532       nir_instr_insert_before(instr, &load->instr);
 533
 534       nir_alu_src val;
 535       val.src = nir_src_for_ssa(&load->def);
 536       val.negate = false;
 537       val.abs = false,
 538       memset(val.swizzle, 0, sizeof val.swizzle);
 539
 540       return val;
 541    }
 542
 543    default:
 544       unreachable("Invalid search value type");
 545    }
 546 }
 547
 548 nir_alu_instr *
 549 nir_replace_instr(nir_alu_instr *instr, const nir_search_expression *search,
 550                   const nir_search_value *replace, void *mem_ctx)
 551 {
 552    uint8_t swizzle[4] = { 0, 0, 0, 0 };
 553
 554    for (unsigned i = 0; i < instr->dest.dest.ssa.num_components; ++i)
 555       swizzle[i] = i;
 556
 557    assert(instr->dest.dest.is_ssa);
 558
 559    struct match_state state;
 560    state.inexact_match = false;
 561    state.has_exact_alu = false;
 562    state.variables_seen = 0;
 563
 564    if (!match_expression(search, instr, instr->dest.dest.ssa.num_components,
 565                          swizzle, &state))
 566       return NULL;
 567
 568    void *bitsize_ctx = ralloc_context(NULL);
 569    bitsize_tree *tree = build_bitsize_tree(bitsize_ctx, &state, replace);
 570    bitsize_tree_filter_up(tree);
 571    bitsize_tree_filter_down(tree, instr->dest.dest.ssa.bit_size);
 572
 573    /* Inserting a mov may be unnecessary.  However, it's much easier to
 574     * simply let copy propagation clean this up than to try to go through
 575     * and rewrite swizzles ourselves.
 576     */
 577    nir_alu_instr *mov = nir_alu_instr_create(mem_ctx, nir_op_imov);
 578    mov->dest.write_mask = instr->dest.write_mask;
 579    nir_ssa_dest_init(&mov->instr, &mov->dest.dest,
 580                      instr->dest.dest.ssa.num_components,
 581                      instr->dest.dest.ssa.bit_size, NULL);
 582
 583    mov->src[0] = construct_value(replace,
 584                                  instr->dest.dest.ssa.num_components, tree,
 585                                  &state, &instr->instr, mem_ctx);
 586    nir_instr_insert_before(&instr->instr, &mov->instr);
 587
 588    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
 589                             nir_src_for_ssa(&mov->dest.dest.ssa));
 590
 591    /* We know this one has no more uses because we just rewrote them all,
 592     * so we can remove it.  The rest of the matched expression, however, we
 593     * don't know so much about.  We'll just let dead code clean them up.
 594     */
 595    nir_instr_remove(&instr->instr);
 596
 597    ralloc_free(bitsize_ctx);
 598
 599    return mov;
 600 }