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    /* If the value has a specific bit size and it doesn't match, bail */
  92    if (value->bit_size &&
  93        nir_src_bit_size(instr->src[src].src) != value->bit_size)
  94       return false;
  95
  96    switch (value->type) {
  97    case nir_search_value_expression:
  98       if (!instr->src[src].src.is_ssa)
  99          return false;
 100
 101       if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_alu)
 102          return false;
 103
 104       return match_expression(nir_search_value_as_expression(value),
 105                               nir_instr_as_alu(instr->src[src].src.ssa->parent_instr),
 106                               num_components, new_swizzle, state);
 107
 108    case nir_search_value_variable: {
 109       nir_search_variable *var = nir_search_value_as_variable(value);
 110       assert(var->variable < NIR_SEARCH_MAX_VARIABLES);
 111
 112       if (state->variables_seen & (1 << var->variable)) {
 113          if (!nir_srcs_equal(state->variables[var->variable].src,
 114                              instr->src[src].src))
 115             return false;
 116
 117          assert(!instr->src[src].abs && !instr->src[src].negate);
 118
 119          for (unsigned i = 0; i < num_components; ++i) {
 120             if (state->variables[var->variable].swizzle[i] != new_swizzle[i])
 121                return false;
 122          }
 123
 124          return true;
 125       } else {
 126          if (var->is_constant &&
 127              instr->src[src].src.ssa->parent_instr->type != nir_instr_type_load_const)
 128             return false;
 129
 130          if (var->type != nir_type_invalid) {
 131             if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_alu)
 132                return false;
 133
 134             nir_alu_instr *src_alu =
 135                nir_instr_as_alu(instr->src[src].src.ssa->parent_instr);
 136
 137             if (nir_alu_type_get_base_type(nir_op_infos[src_alu->op].output_type) !=
 138                 var->type &&
 139                 !(nir_alu_type_get_base_type(var->type) == nir_type_bool &&
 140                   alu_instr_is_bool(src_alu)))
 141                return false;
 142          }
 143
 144          state->variables_seen |= (1 << var->variable);
 145          state->variables[var->variable].src = instr->src[src].src;
 146          state->variables[var->variable].abs = false;
 147          state->variables[var->variable].negate = false;
 148
 149          for (unsigned i = 0; i < 4; ++i) {
 150             if (i < num_components)
 151                state->variables[var->variable].swizzle[i] = new_swizzle[i];
 152             else
 153                state->variables[var->variable].swizzle[i] = 0;
 154          }
 155
 156          return true;
 157       }
 158    }
 159
 160    case nir_search_value_constant: {
 161       nir_search_constant *const_val = nir_search_value_as_constant(value);
 162
 163       if (!instr->src[src].src.is_ssa)
 164          return false;
 165
 166       if (instr->src[src].src.ssa->parent_instr->type != nir_instr_type_load_const)
 167          return false;
 168
 169       nir_load_const_instr *load =
 170          nir_instr_as_load_const(instr->src[src].src.ssa->parent_instr);
 171
 172       switch (const_val->type) {
 173       case nir_type_float:
 174          for (unsigned i = 0; i < num_components; ++i) {
 175             double val;
 176             switch (load->def.bit_size) {
 177             case 32:
 178                val = load->value.f32[new_swizzle[i]];
 179                break;
 180             case 64:
 181                val = load->value.f64[new_swizzle[i]];
 182                break;
 183             default:
 184                unreachable("unknown bit size");
 185             }
 186
 187             if (val != const_val->data.d)
 188                return false;
 189          }
 190          return true;
 191
 192       case nir_type_int:
 193          for (unsigned i = 0; i < num_components; ++i) {
 194             int64_t val;
 195             switch (load->def.bit_size) {
 196             case 32:
 197                val = load->value.i32[new_swizzle[i]];
 198                break;
 199             case 64:
 200                val = load->value.i64[new_swizzle[i]];
 201                break;
 202             default:
 203                unreachable("unknown bit size");
 204             }
 205
 206             if (val != const_val->data.i)
 207                return false;
 208          }
 209          return true;
 210
 211       case nir_type_uint:
 212       case nir_type_bool32:
 213          for (unsigned i = 0; i < num_components; ++i) {
 214             uint64_t val;
 215             switch (load->def.bit_size) {
 216             case 32:
 217                val = load->value.u32[new_swizzle[i]];
 218                break;
 219             case 64:
 220                val = load->value.u64[new_swizzle[i]];
 221                break;
 222             default:
 223                unreachable("unknown bit size");
 224             }
 225
 226             if (val != const_val->data.u)
 227                return false;
 228          }
 229          return true;
 230
 231       default:
 232          unreachable("Invalid alu source type");
 233       }
 234    }
 235
 236    default:
 237       unreachable("Invalid search value type");
 238    }
 239 }
 240
 241 static bool
 242 match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
 243                  unsigned num_components, const uint8_t *swizzle,
 244                  struct match_state *state)
 245 {
 246    if (instr->op != expr->opcode)
 247       return false;
 248
 249    assert(instr->dest.dest.is_ssa);
 250
 251    if (expr->value.bit_size &&
 252        instr->dest.dest.ssa.bit_size != expr->value.bit_size)
 253       return false;
 254
 255    state->inexact_match = expr->inexact || state->inexact_match;
 256    state->has_exact_alu = instr->exact || state->has_exact_alu;
 257    if (state->inexact_match && state->has_exact_alu)
 258       return false;
 259
 260    assert(!instr->dest.saturate);
 261    assert(nir_op_infos[instr->op].num_inputs > 0);
 262
 263    /* If we have an explicitly sized destination, we can only handle the
 264     * identity swizzle.  While dot(vec3(a, b, c).zxy) is a valid
 265     * expression, we don't have the information right now to propagate that
 266     * swizzle through.  We can only properly propagate swizzles if the
 267     * instruction is vectorized.
 268     */
 269    if (nir_op_infos[instr->op].output_size != 0) {
 270       for (unsigned i = 0; i < num_components; i++) {
 271          if (swizzle[i] != i)
 272             return false;
 273       }
 274    }
 275
 276    /* Stash off the current variables_seen bitmask.  This way we can
 277     * restore it prior to matching in the commutative case below.
 278     */
 279    unsigned variables_seen_stash = state->variables_seen;
 280
 281    bool matched = true;
 282    for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
 283       if (!match_value(expr->srcs[i], instr, i, num_components,
 284                        swizzle, state)) {
 285          matched = false;
 286          break;
 287       }
 288    }
 289
 290    if (matched)
 291       return true;
 292
 293    if (nir_op_infos[instr->op].algebraic_properties & NIR_OP_IS_COMMUTATIVE) {
 294       assert(nir_op_infos[instr->op].num_inputs == 2);
 295
 296       /* Restore the variables_seen bitmask.  If we don't do this, then we
 297        * could end up with an erroneous failure due to variables found in the
 298        * first match attempt above not matching those in the second.
 299        */
 300       state->variables_seen = variables_seen_stash;
 301
 302       if (!match_value(expr->srcs[0], instr, 1, num_components,
 303                        swizzle, state))
 304          return false;
 305
 306       return match_value(expr->srcs[1], instr, 0, num_components,
 307                          swizzle, state);
 308    } else {
 309       return false;
 310    }
 311 }
 312
 313 typedef struct bitsize_tree {
 314    unsigned num_srcs;
 315    struct bitsize_tree *srcs[4];
 316
 317    unsigned common_size;
 318    bool is_src_sized[4];
 319    bool is_dest_sized;
 320
 321    unsigned dest_size;
 322    unsigned src_size[4];
 323 } bitsize_tree;
 324
 325 static bitsize_tree *
 326 build_bitsize_tree(void *mem_ctx, struct match_state *state,
 327                    const nir_search_value *value)
 328 {
 329    bitsize_tree *tree = ralloc(mem_ctx, bitsize_tree);
 330
 331    switch (value->type) {
 332    case nir_search_value_expression: {
 333       nir_search_expression *expr = nir_search_value_as_expression(value);
 334       nir_op_info info = nir_op_infos[expr->opcode];
 335       tree->num_srcs = info.num_inputs;
 336       tree->common_size = 0;
 337       for (unsigned i = 0; i < info.num_inputs; i++) {
 338          tree->is_src_sized[i] = !!nir_alu_type_get_type_size(info.input_types[i]);
 339          if (tree->is_src_sized[i])
 340             tree->src_size[i] = nir_alu_type_get_type_size(info.input_types[i]);
 341          tree->srcs[i] = build_bitsize_tree(mem_ctx, state, expr->srcs[i]);
 342       }
 343       tree->is_dest_sized = !!nir_alu_type_get_type_size(info.output_type);
 344       if (tree->is_dest_sized)
 345          tree->dest_size = nir_alu_type_get_type_size(info.output_type);
 346       break;
 347    }
 348
 349    case nir_search_value_variable: {
 350       nir_search_variable *var = nir_search_value_as_variable(value);
 351       tree->num_srcs = 0;
 352       tree->is_dest_sized = true;
 353       tree->dest_size = nir_src_bit_size(state->variables[var->variable].src);
 354       break;
 355    }
 356
 357    case nir_search_value_constant: {
 358       tree->num_srcs = 0;
 359       tree->is_dest_sized = false;
 360       tree->common_size = 0;
 361       break;
 362    }
 363    }
 364
 365    if (value->bit_size) {
 366       assert(!tree->is_dest_sized || tree->dest_size == value->bit_size);
 367       tree->common_size = value->bit_size;
 368    }
 369
 370    return tree;
 371 }
 372
 373 static unsigned
 374 bitsize_tree_filter_up(bitsize_tree *tree)
 375 {
 376    for (unsigned i = 0; i < tree->num_srcs; i++) {
 377       unsigned src_size = bitsize_tree_filter_up(tree->srcs[i]);
 378       if (src_size == 0)
 379          continue;
 380
 381       if (tree->is_src_sized[i]) {
 382          assert(src_size == tree->src_size[i]);
 383       } else if (tree->common_size != 0) {
 384          assert(src_size == tree->common_size);
 385          tree->src_size[i] = src_size;
 386       } else {
 387          tree->common_size = src_size;
 388          tree->src_size[i] = src_size;
 389       }
 390    }
 391
 392    if (tree->num_srcs && tree->common_size) {
 393       if (tree->dest_size == 0)
 394          tree->dest_size = tree->common_size;
 395       else if (!tree->is_dest_sized)
 396          assert(tree->dest_size == tree->common_size);
 397
 398       for (unsigned i = 0; i < tree->num_srcs; i++) {
 399          if (!tree->src_size[i])
 400             tree->src_size[i] = tree->common_size;
 401       }
 402    }
 403
 404    return tree->dest_size;
 405 }
 406
 407 static void
 408 bitsize_tree_filter_down(bitsize_tree *tree, unsigned size)
 409 {
 410    if (tree->dest_size)
 411       assert(tree->dest_size == size);
 412    else
 413       tree->dest_size = size;
 414
 415    if (!tree->is_dest_sized) {
 416       if (tree->common_size)
 417          assert(tree->common_size == size);
 418       else
 419          tree->common_size = size;
 420    }
 421
 422    for (unsigned i = 0; i < tree->num_srcs; i++) {
 423       if (!tree->src_size[i]) {
 424          assert(tree->common_size);
 425          tree->src_size[i] = tree->common_size;
 426       }
 427       bitsize_tree_filter_down(tree->srcs[i], tree->src_size[i]);
 428    }
 429 }
 430
 431 static nir_alu_src
 432 construct_value(const nir_search_value *value,
 433                 unsigned num_components, bitsize_tree *bitsize,
 434                 struct match_state *state,
 435                 nir_instr *instr, void *mem_ctx)
 436 {
 437    switch (value->type) {
 438    case nir_search_value_expression: {
 439       const nir_search_expression *expr = nir_search_value_as_expression(value);
 440
 441       if (nir_op_infos[expr->opcode].output_size != 0)
 442          num_components = nir_op_infos[expr->opcode].output_size;
 443
 444       nir_alu_instr *alu = nir_alu_instr_create(mem_ctx, expr->opcode);
 445       nir_ssa_dest_init(&alu->instr, &alu->dest.dest, num_components,
 446                         bitsize->dest_size, NULL);
 447       alu->dest.write_mask = (1 << num_components) - 1;
 448       alu->dest.saturate = false;
 449
 450       /* We have no way of knowing what values in a given search expression
 451        * map to a particular replacement value.  Therefore, if the
 452        * expression we are replacing has any exact values, the entire
 453        * replacement should be exact.
 454        */
 455       alu->exact = state->has_exact_alu;
 456
 457       for (unsigned i = 0; i < nir_op_infos[expr->opcode].num_inputs; i++) {
 458          /* If the source is an explicitly sized source, then we need to reset
 459           * the number of components to match.
 460           */
 461          if (nir_op_infos[alu->op].input_sizes[i] != 0)
 462             num_components = nir_op_infos[alu->op].input_sizes[i];
 463
 464          alu->src[i] = construct_value(expr->srcs[i],
 465                                        num_components, bitsize->srcs[i],
 466                                        state, instr, mem_ctx);
 467       }
 468
 469       nir_instr_insert_before(instr, &alu->instr);
 470
 471       nir_alu_src val;
 472       val.src = nir_src_for_ssa(&alu->dest.dest.ssa);
 473       val.negate = false;
 474       val.abs = false,
 475       memcpy(val.swizzle, identity_swizzle, sizeof val.swizzle);
 476
 477       return val;
 478    }
 479
 480    case nir_search_value_variable: {
 481       const nir_search_variable *var = nir_search_value_as_variable(value);
 482       assert(state->variables_seen & (1 << var->variable));
 483
 484       nir_alu_src val = { NIR_SRC_INIT };
 485       nir_alu_src_copy(&val, &state->variables[var->variable], mem_ctx);
 486
 487       assert(!var->is_constant);
 488
 489       return val;
 490    }
 491
 492    case nir_search_value_constant: {
 493       const nir_search_constant *c = nir_search_value_as_constant(value);
 494       nir_load_const_instr *load =
 495          nir_load_const_instr_create(mem_ctx, 1, bitsize->dest_size);
 496
 497       switch (c->type) {
 498       case nir_type_float:
 499          load->def.name = ralloc_asprintf(load, "%f", c->data.d);
 500          switch (bitsize->dest_size) {
 501          case 32:
 502             load->value.f32[0] = c->data.d;
 503             break;
 504          case 64:
 505             load->value.f64[0] = c->data.d;
 506             break;
 507          default:
 508             unreachable("unknown bit size");
 509          }
 510          break;
 511
 512       case nir_type_int:
 513          load->def.name = ralloc_asprintf(load, "%" PRIi64, c->data.i);
 514          switch (bitsize->dest_size) {
 515          case 32:
 516             load->value.i32[0] = c->data.i;
 517             break;
 518          case 64:
 519             load->value.i64[0] = c->data.i;
 520             break;
 521          default:
 522             unreachable("unknown bit size");
 523          }
 524          break;
 525
 526       case nir_type_uint:
 527          load->def.name = ralloc_asprintf(load, "%" PRIu64, c->data.u);
 528          switch (bitsize->dest_size) {
 529          case 32:
 530             load->value.u32[0] = c->data.u;
 531             break;
 532          case 64:
 533             load->value.u64[0] = c->data.u;
 534             break;
 535          default:
 536             unreachable("unknown bit size");
 537          }
 538          break;
 539
 540       case nir_type_bool32:
 541          load->value.u32[0] = c->data.u;
 542          break;
 543       default:
 544          unreachable("Invalid alu source type");
 545       }
 546
 547       nir_instr_insert_before(instr, &load->instr);
 548
 549       nir_alu_src val;
 550       val.src = nir_src_for_ssa(&load->def);
 551       val.negate = false;
 552       val.abs = false,
 553       memset(val.swizzle, 0, sizeof val.swizzle);
 554
 555       return val;
 556    }
 557
 558    default:
 559       unreachable("Invalid search value type");
 560    }
 561 }
 562
 563 nir_alu_instr *
 564 nir_replace_instr(nir_alu_instr *instr, const nir_search_expression *search,
 565                   const nir_search_value *replace, void *mem_ctx)
 566 {
 567    uint8_t swizzle[4] = { 0, 0, 0, 0 };
 568
 569    for (unsigned i = 0; i < instr->dest.dest.ssa.num_components; ++i)
 570       swizzle[i] = i;
 571
 572    assert(instr->dest.dest.is_ssa);
 573
 574    struct match_state state;
 575    state.inexact_match = false;
 576    state.has_exact_alu = false;
 577    state.variables_seen = 0;
 578
 579    if (!match_expression(search, instr, instr->dest.dest.ssa.num_components,
 580                          swizzle, &state))
 581       return NULL;
 582
 583    void *bitsize_ctx = ralloc_context(NULL);
 584    bitsize_tree *tree = build_bitsize_tree(bitsize_ctx, &state, replace);
 585    bitsize_tree_filter_up(tree);
 586    bitsize_tree_filter_down(tree, instr->dest.dest.ssa.bit_size);
 587
 588    /* Inserting a mov may be unnecessary.  However, it's much easier to
 589     * simply let copy propagation clean this up than to try to go through
 590     * and rewrite swizzles ourselves.
 591     */
 592    nir_alu_instr *mov = nir_alu_instr_create(mem_ctx, nir_op_imov);
 593    mov->dest.write_mask = instr->dest.write_mask;
 594    nir_ssa_dest_init(&mov->instr, &mov->dest.dest,
 595                      instr->dest.dest.ssa.num_components,
 596                      instr->dest.dest.ssa.bit_size, NULL);
 597
 598    mov->src[0] = construct_value(replace,
 599                                  instr->dest.dest.ssa.num_components, tree,
 600                                  &state, &instr->instr, mem_ctx);
 601    nir_instr_insert_before(&instr->instr, &mov->instr);
 602
 603    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
 604                             nir_src_for_ssa(&mov->dest.dest.ssa));
 605
 606    /* We know this one has no more uses because we just rewrote them all,
 607     * so we can remove it.  The rest of the matched expression, however, we
 608     * don't know so much about.  We'll just let dead code clean them up.
 609     */
 610    nir_instr_remove(&instr->instr);
 611
 612    ralloc_free(bitsize_ctx);
 613
 614    return mov;
 615 }