src/glsl/opt_algebraic.cpp

   1 /*
   2  * Copyright © 2010 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
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * \file opt_algebraic.cpp
  26  *
  27  * Takes advantage of association, commutivity, and other algebraic
  28  * properties to simplify expressions.
  29  */
  30
  31 #include "ir.h"
  32 #include "ir_visitor.h"
  33 #include "ir_rvalue_visitor.h"
  34 #include "ir_optimization.h"
  35 #include "ir_builder.h"
  36 #include "glsl_types.h"
  37
  38 using namespace ir_builder;
  39
  40 namespace {
  41
  42 /**
  43  * Visitor class for replacing expressions with ir_constant values.
  44  */
  45
  46 class ir_algebraic_visitor : public ir_rvalue_visitor {
  47 public:
  48    ir_algebraic_visitor(bool native_integers,
  49                         const struct gl_shader_compiler_options *options)
  50       : options(options)
  51    {
  52       this->progress = false;
  53       this->mem_ctx = NULL;
  54       this->native_integers = native_integers;
  55    }
  56
  57    virtual ~ir_algebraic_visitor()
  58    {
  59    }
  60
  61    ir_rvalue *handle_expression(ir_expression *ir);
  62    void handle_rvalue(ir_rvalue **rvalue);
  63    bool reassociate_constant(ir_expression *ir1,
  64                              int const_index,
  65                              ir_constant *constant,
  66                              ir_expression *ir2);
  67    void reassociate_operands(ir_expression *ir1,
  68                              int op1,
  69                              ir_expression *ir2,
  70                              int op2);
  71    ir_rvalue *swizzle_if_required(ir_expression *expr,
  72                                   ir_rvalue *operand);
  73
  74    const struct gl_shader_compiler_options *options;
  75    void *mem_ctx;
  76
  77    bool native_integers;
  78    bool progress;
  79 };
  80
  81 } /* unnamed namespace */
  82
  83 static inline bool
  84 is_vec_zero(ir_constant *ir)
  85 {
  86    return (ir == NULL) ? false : ir->is_zero();
  87 }
  88
  89 static inline bool
  90 is_vec_one(ir_constant *ir)
  91 {
  92    return (ir == NULL) ? false : ir->is_one();
  93 }
  94
  95 static inline bool
  96 is_vec_two(ir_constant *ir)
  97 {
  98    return (ir == NULL) ? false : ir->is_value(2.0, 2);
  99 }
 100
 101 static inline bool
 102 is_vec_negative_one(ir_constant *ir)
 103 {
 104    return (ir == NULL) ? false : ir->is_negative_one();
 105 }
 106
 107 static inline bool
 108 is_vec_basis(ir_constant *ir)
 109 {
 110    return (ir == NULL) ? false : ir->is_basis();
 111 }
 112
 113 static inline bool
 114 is_valid_vec_const(ir_constant *ir)
 115 {
 116    if (ir == NULL)
 117       return false;
 118
 119    if (!ir->type->is_scalar() && !ir->type->is_vector())
 120       return false;
 121
 122    return true;
 123 }
 124
 125 static inline bool
 126 is_less_than_one(ir_constant *ir)
 127 {
 128    if (!is_valid_vec_const(ir))
 129       return false;
 130
 131    unsigned component = 0;
 132    for (int c = 0; c < ir->type->vector_elements; c++) {
 133       if (ir->get_float_component(c) < 1.0f)
 134          component++;
 135    }
 136
 137    return (component == ir->type->vector_elements);
 138 }
 139
 140 static inline bool
 141 is_greater_than_zero(ir_constant *ir)
 142 {
 143    if (!is_valid_vec_const(ir))
 144       return false;
 145
 146    unsigned component = 0;
 147    for (int c = 0; c < ir->type->vector_elements; c++) {
 148       if (ir->get_float_component(c) > 0.0f)
 149          component++;
 150    }
 151
 152    return (component == ir->type->vector_elements);
 153 }
 154
 155 static void
 156 update_type(ir_expression *ir)
 157 {
 158    if (ir->operands[0]->type->is_vector())
 159       ir->type = ir->operands[0]->type;
 160    else
 161       ir->type = ir->operands[1]->type;
 162 }
 163
 164 /* Recognize (v.x + v.y) + (v.z + v.w) as dot(v, 1.0) */
 165 static ir_expression *
 166 try_replace_with_dot(ir_expression *expr0, ir_expression *expr1, void *mem_ctx)
 167 {
 168    if (expr0 && expr0->operation == ir_binop_add &&
 169        expr0->type->is_float() &&
 170        expr1 && expr1->operation == ir_binop_add &&
 171        expr1->type->is_float()) {
 172       ir_swizzle *x = expr0->operands[0]->as_swizzle();
 173       ir_swizzle *y = expr0->operands[1]->as_swizzle();
 174       ir_swizzle *z = expr1->operands[0]->as_swizzle();
 175       ir_swizzle *w = expr1->operands[1]->as_swizzle();
 176
 177       if (!x || x->mask.num_components != 1 ||
 178           !y || y->mask.num_components != 1 ||
 179           !z || z->mask.num_components != 1 ||
 180           !w || w->mask.num_components != 1) {
 181          return NULL;
 182       }
 183
 184       bool swiz_seen[4] = {false, false, false, false};
 185       swiz_seen[x->mask.x] = true;
 186       swiz_seen[y->mask.x] = true;
 187       swiz_seen[z->mask.x] = true;
 188       swiz_seen[w->mask.x] = true;
 189
 190       if (!swiz_seen[0] || !swiz_seen[1] ||
 191           !swiz_seen[2] || !swiz_seen[3]) {
 192          return NULL;
 193       }
 194
 195       if (x->val->equals(y->val) &&
 196           x->val->equals(z->val) &&
 197           x->val->equals(w->val)) {
 198          return dot(x->val, new(mem_ctx) ir_constant(1.0f, 4));
 199       }
 200    }
 201    return NULL;
 202 }
 203
 204 void
 205 ir_algebraic_visitor::reassociate_operands(ir_expression *ir1,
 206                                            int op1,
 207                                            ir_expression *ir2,
 208                                            int op2)
 209 {
 210    ir_rvalue *temp = ir2->operands[op2];
 211    ir2->operands[op2] = ir1->operands[op1];
 212    ir1->operands[op1] = temp;
 213
 214    /* Update the type of ir2.  The type of ir1 won't have changed --
 215     * base types matched, and at least one of the operands of the 2
 216     * binops is still a vector if any of them were.
 217     */
 218    update_type(ir2);
 219
 220    this->progress = true;
 221 }
 222
 223 /**
 224  * Reassociates a constant down a tree of adds or multiplies.
 225  *
 226  * Consider (2 * (a * (b * 0.5))).  We want to send up with a * b.
 227  */
 228 bool
 229 ir_algebraic_visitor::reassociate_constant(ir_expression *ir1, int const_index,
 230                                            ir_constant *constant,
 231                                            ir_expression *ir2)
 232 {
 233    if (!ir2 || ir1->operation != ir2->operation)
 234       return false;
 235
 236    /* Don't want to even think about matrices. */
 237    if (ir1->operands[0]->type->is_matrix() ||
 238        ir1->operands[1]->type->is_matrix() ||
 239        ir2->operands[0]->type->is_matrix() ||
 240        ir2->operands[1]->type->is_matrix())
 241       return false;
 242
 243    ir_constant *ir2_const[2];
 244    ir2_const[0] = ir2->operands[0]->constant_expression_value();
 245    ir2_const[1] = ir2->operands[1]->constant_expression_value();
 246
 247    if (ir2_const[0] && ir2_const[1])
 248       return false;
 249
 250    if (ir2_const[0]) {
 251       reassociate_operands(ir1, const_index, ir2, 1);
 252       return true;
 253    } else if (ir2_const[1]) {
 254       reassociate_operands(ir1, const_index, ir2, 0);
 255       return true;
 256    }
 257
 258    if (reassociate_constant(ir1, const_index, constant,
 259                             ir2->operands[0]->as_expression())) {
 260       update_type(ir2);
 261       return true;
 262    }
 263
 264    if (reassociate_constant(ir1, const_index, constant,
 265                             ir2->operands[1]->as_expression())) {
 266       update_type(ir2);
 267       return true;
 268    }
 269
 270    return false;
 271 }
 272
 273 /* When eliminating an expression and just returning one of its operands,
 274  * we may need to swizzle that operand out to a vector if the expression was
 275  * vector type.
 276  */
 277 ir_rvalue *
 278 ir_algebraic_visitor::swizzle_if_required(ir_expression *expr,
 279                                           ir_rvalue *operand)
 280 {
 281    if (expr->type->is_vector() && operand->type->is_scalar()) {
 282       return new(mem_ctx) ir_swizzle(operand, 0, 0, 0, 0,
 283                                      expr->type->vector_elements);
 284    } else
 285       return operand;
 286 }
 287
 288 ir_rvalue *
 289 ir_algebraic_visitor::handle_expression(ir_expression *ir)
 290 {
 291    ir_constant *op_const[4] = {NULL, NULL, NULL, NULL};
 292    ir_expression *op_expr[4] = {NULL, NULL, NULL, NULL};
 293    unsigned int i;
 294
 295    assert(ir->get_num_operands() <= 4);
 296    for (i = 0; i < ir->get_num_operands(); i++) {
 297       if (ir->operands[i]->type->is_matrix())
 298          return ir;
 299
 300       op_const[i] = ir->operands[i]->constant_expression_value();
 301       op_expr[i] = ir->operands[i]->as_expression();
 302    }
 303
 304    if (this->mem_ctx == NULL)
 305       this->mem_ctx = ralloc_parent(ir);
 306
 307    switch (ir->operation) {
 308    case ir_unop_bit_not:
 309       if (op_expr[0] && op_expr[0]->operation == ir_unop_bit_not)
 310          return op_expr[0]->operands[0];
 311       break;
 312
 313    case ir_unop_abs:
 314       if (op_expr[0] == NULL)
 315          break;
 316
 317       switch (op_expr[0]->operation) {
 318       case ir_unop_abs:
 319       case ir_unop_neg:
 320          return abs(op_expr[0]->operands[0]);
 321       default:
 322          break;
 323       }
 324       break;
 325
 326    case ir_unop_neg:
 327       if (op_expr[0] == NULL)
 328          break;
 329
 330       if (op_expr[0]->operation == ir_unop_neg) {
 331          return op_expr[0]->operands[0];
 332       }
 333       break;
 334
 335    case ir_unop_exp:
 336       if (op_expr[0] == NULL)
 337          break;
 338
 339       if (op_expr[0]->operation == ir_unop_log) {
 340          return op_expr[0]->operands[0];
 341       }
 342       break;
 343
 344    case ir_unop_log:
 345       if (op_expr[0] == NULL)
 346          break;
 347
 348       if (op_expr[0]->operation == ir_unop_exp) {
 349          return op_expr[0]->operands[0];
 350       }
 351       break;
 352
 353    case ir_unop_exp2:
 354       if (op_expr[0] == NULL)
 355          break;
 356
 357       if (op_expr[0]->operation == ir_unop_log2) {
 358          return op_expr[0]->operands[0];
 359       }
 360       break;
 361
 362    case ir_unop_log2:
 363       if (op_expr[0] == NULL)
 364          break;
 365
 366       if (op_expr[0]->operation == ir_unop_exp2) {
 367          return op_expr[0]->operands[0];
 368       }
 369       break;
 370
 371    case ir_unop_logic_not: {
 372       enum ir_expression_operation new_op = ir_unop_logic_not;
 373
 374       if (op_expr[0] == NULL)
 375          break;
 376
 377       switch (op_expr[0]->operation) {
 378       case ir_binop_less:    new_op = ir_binop_gequal;  break;
 379       case ir_binop_greater: new_op = ir_binop_lequal;  break;
 380       case ir_binop_lequal:  new_op = ir_binop_greater; break;
 381       case ir_binop_gequal:  new_op = ir_binop_less;    break;
 382       case ir_binop_equal:   new_op = ir_binop_nequal;  break;
 383       case ir_binop_nequal:  new_op = ir_binop_equal;   break;
 384       case ir_binop_all_equal:   new_op = ir_binop_any_nequal;  break;
 385       case ir_binop_any_nequal:  new_op = ir_binop_all_equal;   break;
 386
 387       default:
 388          /* The default case handler is here to silence a warning from GCC.
 389           */
 390          break;
 391       }
 392
 393       if (new_op != ir_unop_logic_not) {
 394          return new(mem_ctx) ir_expression(new_op,
 395                                            ir->type,
 396                                            op_expr[0]->operands[0],
 397                                            op_expr[0]->operands[1]);
 398       }
 399
 400       break;
 401    }
 402
 403    case ir_binop_add:
 404       if (is_vec_zero(op_const[0]))
 405          return ir->operands[1];
 406       if (is_vec_zero(op_const[1]))
 407          return ir->operands[0];
 408
 409       /* Reassociate addition of constants so that we can do constant
 410        * folding.
 411        */
 412       if (op_const[0] && !op_const[1])
 413          reassociate_constant(ir, 0, op_const[0], op_expr[1]);
 414       if (op_const[1] && !op_const[0])
 415          reassociate_constant(ir, 1, op_const[1], op_expr[0]);
 416
 417       /* Recognize (v.x + v.y) + (v.z + v.w) as dot(v, 1.0) */
 418       if (options->OptimizeForAOS) {
 419          ir_expression *expr = try_replace_with_dot(op_expr[0], op_expr[1],
 420                                                     mem_ctx);
 421          if (expr)
 422             return expr;
 423       }
 424
 425       /* Replace (-x + y) * a + x and commutative variations with lrp(x, y, a).
 426        *
 427        * (-x + y) * a + x
 428        * (x * -a) + (y * a) + x
 429        * x + (x * -a) + (y * a)
 430        * x * (1 - a) + y * a
 431        * lrp(x, y, a)
 432        */
 433       for (int mul_pos = 0; mul_pos < 2; mul_pos++) {
 434          ir_expression *mul = op_expr[mul_pos];
 435
 436          if (!mul || mul->operation != ir_binop_mul)
 437             continue;
 438
 439          /* Multiply found on one of the operands. Now check for an
 440           * inner addition operation.
 441           */
 442          for (int inner_add_pos = 0; inner_add_pos < 2; inner_add_pos++) {
 443             ir_expression *inner_add =
 444                mul->operands[inner_add_pos]->as_expression();
 445
 446             if (!inner_add || inner_add->operation != ir_binop_add)
 447                continue;
 448
 449             /* Inner addition found on one of the operands. Now check for
 450              * one of the operands of the inner addition to be the negative
 451              * of x_operand.
 452              */
 453             for (int neg_pos = 0; neg_pos < 2; neg_pos++) {
 454                ir_expression *neg =
 455                   inner_add->operands[neg_pos]->as_expression();
 456
 457                if (!neg || neg->operation != ir_unop_neg)
 458                   continue;
 459
 460                ir_rvalue *x_operand = ir->operands[1 - mul_pos];
 461
 462                if (!neg->operands[0]->equals(x_operand))
 463                   continue;
 464
 465                ir_rvalue *y_operand = inner_add->operands[1 - neg_pos];
 466                ir_rvalue *a_operand = mul->operands[1 - inner_add_pos];
 467
 468                if (x_operand->type != y_operand->type ||
 469                    x_operand->type != a_operand->type)
 470                   continue;
 471
 472                return lrp(x_operand, y_operand, a_operand);
 473             }
 474          }
 475       }
 476
 477       break;
 478
 479    case ir_binop_sub:
 480       if (is_vec_zero(op_const[0]))
 481          return neg(ir->operands[1]);
 482       if (is_vec_zero(op_const[1]))
 483          return ir->operands[0];
 484       break;
 485
 486    case ir_binop_mul:
 487       if (is_vec_one(op_const[0]))
 488          return ir->operands[1];
 489       if (is_vec_one(op_const[1]))
 490          return ir->operands[0];
 491
 492       if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1]))
 493          return ir_constant::zero(ir, ir->type);
 494
 495       if (is_vec_negative_one(op_const[0]))
 496          return neg(ir->operands[1]);
 497       if (is_vec_negative_one(op_const[1]))
 498          return neg(ir->operands[0]);
 499
 500
 501       /* Reassociate multiplication of constants so that we can do
 502        * constant folding.
 503        */
 504       if (op_const[0] && !op_const[1])
 505          reassociate_constant(ir, 0, op_const[0], op_expr[1]);
 506       if (op_const[1] && !op_const[0])
 507          reassociate_constant(ir, 1, op_const[1], op_expr[0]);
 508
 509       break;
 510
 511    case ir_binop_div:
 512       if (is_vec_one(op_const[0]) && ir->type->base_type == GLSL_TYPE_FLOAT) {
 513          return new(mem_ctx) ir_expression(ir_unop_rcp,
 514                                            ir->operands[1]->type,
 515                                            ir->operands[1],
 516                                            NULL);
 517       }
 518       if (is_vec_one(op_const[1]))
 519          return ir->operands[0];
 520       break;
 521
 522    case ir_binop_dot:
 523       if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1]))
 524          return ir_constant::zero(mem_ctx, ir->type);
 525
 526       if (is_vec_basis(op_const[0])) {
 527          unsigned component = 0;
 528          for (unsigned c = 0; c < op_const[0]->type->vector_elements; c++) {
 529             if (op_const[0]->value.f[c] == 1.0)
 530                component = c;
 531          }
 532          return new(mem_ctx) ir_swizzle(ir->operands[1], component, 0, 0, 0, 1);
 533       }
 534       if (is_vec_basis(op_const[1])) {
 535          unsigned component = 0;
 536          for (unsigned c = 0; c < op_const[1]->type->vector_elements; c++) {
 537             if (op_const[1]->value.f[c] == 1.0)
 538                component = c;
 539          }
 540          return new(mem_ctx) ir_swizzle(ir->operands[0], component, 0, 0, 0, 1);
 541       }
 542       break;
 543
 544    case ir_binop_less:
 545    case ir_binop_lequal:
 546    case ir_binop_greater:
 547    case ir_binop_gequal:
 548    case ir_binop_equal:
 549    case ir_binop_nequal:
 550       for (int add_pos = 0; add_pos < 2; add_pos++) {
 551          ir_expression *add = op_expr[add_pos];
 552
 553          if (!add || add->operation != ir_binop_add)
 554             continue;
 555
 556          ir_constant *zero = op_const[1 - add_pos];
 557          if (!is_vec_zero(zero))
 558             continue;
 559
 560          return new(mem_ctx) ir_expression(ir->operation,
 561                                            add->operands[0],
 562                                            neg(add->operands[1]));
 563       }
 564       break;
 565
 566    case ir_binop_rshift:
 567    case ir_binop_lshift:
 568       /* 0 >> x == 0 */
 569       if (is_vec_zero(op_const[0]))
 570          return ir->operands[0];
 571       /* x >> 0 == x */
 572       if (is_vec_zero(op_const[1]))
 573          return ir->operands[0];
 574       break;
 575
 576    case ir_binop_logic_and:
 577       if (is_vec_one(op_const[0])) {
 578          return ir->operands[1];
 579       } else if (is_vec_one(op_const[1])) {
 580          return ir->operands[0];
 581       } else if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1])) {
 582          return ir_constant::zero(mem_ctx, ir->type);
 583       } else if (op_expr[0] && op_expr[0]->operation == ir_unop_logic_not &&
 584                  op_expr[1] && op_expr[1]->operation == ir_unop_logic_not) {
 585          /* De Morgan's Law:
 586           *    (not A) and (not B) === not (A or B)
 587           */
 588          return logic_not(logic_or(op_expr[0]->operands[0],
 589                                    op_expr[1]->operands[0]));
 590       } else if (ir->operands[0]->equals(ir->operands[1])) {
 591          /* (a && a) == a */
 592          return ir->operands[0];
 593       }
 594       break;
 595
 596    case ir_binop_logic_xor:
 597       if (is_vec_zero(op_const[0])) {
 598          return ir->operands[1];
 599       } else if (is_vec_zero(op_const[1])) {
 600          return ir->operands[0];
 601       } else if (is_vec_one(op_const[0])) {
 602          return logic_not(ir->operands[1]);
 603       } else if (is_vec_one(op_const[1])) {
 604          return logic_not(ir->operands[0]);
 605       } else if (ir->operands[0]->equals(ir->operands[1])) {
 606          /* (a ^^ a) == false */
 607          return ir_constant::zero(mem_ctx, ir->type);
 608       }
 609       break;
 610
 611    case ir_binop_logic_or:
 612       if (is_vec_zero(op_const[0])) {
 613          return ir->operands[1];
 614       } else if (is_vec_zero(op_const[1])) {
 615          return ir->operands[0];
 616       } else if (is_vec_one(op_const[0]) || is_vec_one(op_const[1])) {
 617          ir_constant_data data;
 618
 619          for (unsigned i = 0; i < 16; i++)
 620             data.b[i] = true;
 621
 622          return new(mem_ctx) ir_constant(ir->type, &data);
 623       } else if (op_expr[0] && op_expr[0]->operation == ir_unop_logic_not &&
 624                  op_expr[1] && op_expr[1]->operation == ir_unop_logic_not) {
 625          /* De Morgan's Law:
 626           *    (not A) or (not B) === not (A and B)
 627           */
 628          return logic_not(logic_and(op_expr[0]->operands[0],
 629                                     op_expr[1]->operands[0]));
 630       } else if (ir->operands[0]->equals(ir->operands[1])) {
 631          /* (a || a) == a */
 632          return ir->operands[0];
 633       }
 634       break;
 635
 636    case ir_binop_pow:
 637       /* 1^x == 1 */
 638       if (is_vec_one(op_const[0]))
 639          return op_const[0];
 640
 641       /* x^1 == x */
 642       if (is_vec_one(op_const[1]))
 643          return ir->operands[0];
 644
 645       /* pow(2,x) == exp2(x) */
 646       if (is_vec_two(op_const[0]))
 647          return expr(ir_unop_exp2, ir->operands[1]);
 648
 649       if (is_vec_two(op_const[1])) {
 650          ir_variable *x = new(ir) ir_variable(ir->operands[1]->type, "x",
 651                                               ir_var_temporary);
 652          base_ir->insert_before(x);
 653          base_ir->insert_before(assign(x, ir->operands[0]));
 654          return mul(x, x);
 655       }
 656
 657       break;
 658
 659    case ir_binop_min:
 660    case ir_binop_max:
 661       if (ir->type->base_type != GLSL_TYPE_FLOAT)
 662          break;
 663
 664       /* Replace min(max) operations and its commutative combinations with
 665        * a saturate operation
 666        */
 667       for (int op = 0; op < 2; op++) {
 668          ir_expression *minmax = op_expr[op];
 669          ir_constant *outer_const = op_const[1 - op];
 670          ir_expression_operation op_cond = (ir->operation == ir_binop_max) ?
 671             ir_binop_min : ir_binop_max;
 672
 673          if (!minmax || !outer_const || (minmax->operation != op_cond))
 674             continue;
 675
 676          /* Found a min(max) combination. Now try to see if its operands
 677           * meet our conditions that we can do just a single saturate operation
 678           */
 679          for (int minmax_op = 0; minmax_op < 2; minmax_op++) {
 680             ir_rvalue *inner_val_a = minmax->operands[minmax_op];
 681             ir_rvalue *inner_val_b = minmax->operands[1 - minmax_op];
 682
 683             if (!inner_val_a || !inner_val_b)
 684                continue;
 685
 686             /* Found a {min|max} ({max|min} (x, 0.0), 1.0) operation and its variations */
 687             if ((outer_const->is_one() && inner_val_a->is_zero()) ||
 688                 (inner_val_a->is_one() && outer_const->is_zero()))
 689                return saturate(inner_val_b);
 690
 691             /* Found a {min|max} ({max|min} (x, 0.0), b) where b < 1.0
 692              * and its variations
 693              */
 694             if (is_less_than_one(outer_const) && inner_val_b->is_zero())
 695                return expr(ir_binop_min, saturate(inner_val_a), outer_const);
 696
 697             if (!inner_val_b->as_constant())
 698                continue;
 699
 700             if (is_less_than_one(inner_val_b->as_constant()) && outer_const->is_zero())
 701                return expr(ir_binop_min, saturate(inner_val_a), inner_val_b);
 702
 703             /* Found a {min|max} ({max|min} (x, b), 1.0), where b > 0.0
 704              * and its variations
 705              */
 706             if (outer_const->is_one() && is_greater_than_zero(inner_val_b->as_constant()))
 707                return expr(ir_binop_max, saturate(inner_val_a), inner_val_b);
 708             if (inner_val_b->as_constant()->is_one() && is_greater_than_zero(outer_const))
 709                return expr(ir_binop_max, saturate(inner_val_a), outer_const);
 710          }
 711       }
 712
 713       break;
 714
 715    case ir_unop_rcp:
 716       if (op_expr[0] && op_expr[0]->operation == ir_unop_rcp)
 717          return op_expr[0]->operands[0];
 718
 719       /* While ir_to_mesa.cpp will lower sqrt(x) to rcp(rsq(x)), it does so at
 720        * its IR level, so we can always apply this transformation.
 721        */
 722       if (op_expr[0] && op_expr[0]->operation == ir_unop_rsq)
 723          return sqrt(op_expr[0]->operands[0]);
 724
 725       /* As far as we know, all backends are OK with rsq. */
 726       if (op_expr[0] && op_expr[0]->operation == ir_unop_sqrt) {
 727          return rsq(op_expr[0]->operands[0]);
 728       }
 729
 730       break;
 731
 732    case ir_triop_fma:
 733       /* Operands are op0 * op1 + op2. */
 734       if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1])) {
 735          return ir->operands[2];
 736       } else if (is_vec_zero(op_const[2])) {
 737          return mul(ir->operands[0], ir->operands[1]);
 738       } else if (is_vec_one(op_const[0])) {
 739          return add(ir->operands[1], ir->operands[2]);
 740       } else if (is_vec_one(op_const[1])) {
 741          return add(ir->operands[0], ir->operands[2]);
 742       }
 743       break;
 744
 745    case ir_triop_lrp:
 746       /* Operands are (x, y, a). */
 747       if (is_vec_zero(op_const[2])) {
 748          return ir->operands[0];
 749       } else if (is_vec_one(op_const[2])) {
 750          return ir->operands[1];
 751       } else if (ir->operands[0]->equals(ir->operands[1])) {
 752          return ir->operands[0];
 753       } else if (is_vec_zero(op_const[0])) {
 754          return mul(ir->operands[1], ir->operands[2]);
 755       } else if (is_vec_zero(op_const[1])) {
 756          unsigned op2_components = ir->operands[2]->type->vector_elements;
 757          ir_constant *one = new(mem_ctx) ir_constant(1.0f, op2_components);
 758          return mul(ir->operands[0], add(one, neg(ir->operands[2])));
 759       }
 760       break;
 761
 762    case ir_triop_csel:
 763       if (is_vec_one(op_const[0]))
 764          return ir->operands[1];
 765       if (is_vec_zero(op_const[0]))
 766          return ir->operands[2];
 767       break;
 768
 769    default:
 770       break;
 771    }
 772
 773    return ir;
 774 }
 775
 776 void
 777 ir_algebraic_visitor::handle_rvalue(ir_rvalue **rvalue)
 778 {
 779    if (!*rvalue)
 780       return;
 781
 782    ir_expression *expr = (*rvalue)->as_expression();
 783    if (!expr || expr->operation == ir_quadop_vector)
 784       return;
 785
 786    ir_rvalue *new_rvalue = handle_expression(expr);
 787    if (new_rvalue == *rvalue)
 788       return;
 789
 790    /* If the expr used to be some vec OP scalar returning a vector, and the
 791     * optimization gave us back a scalar, we still need to turn it into a
 792     * vector.
 793     */
 794    *rvalue = swizzle_if_required(expr, new_rvalue);
 795
 796    this->progress = true;
 797 }
 798
 799 bool
 800 do_algebraic(exec_list *instructions, bool native_integers,
 801              const struct gl_shader_compiler_options *options)
 802 {
 803    ir_algebraic_visitor v(native_integers, options);
 804
 805    visit_list_elements(&v, instructions);
 806
 807    return v.progress;
 808 }