simplify.c

   1 /*
   2  * Simplify - do instruction simplification before CSE
   3  *
   4  * Copyright (C) 2004 Linus Torvalds
   5  */
   6
   7 #include <assert.h>
   8
   9 #include "parse.h"
  10 #include "expression.h"
  11 #include "linearize.h"
  12 #include "flow.h"
  13
  14 /* Find the trivial parent for a phi-source */
  15 static struct basic_block *phi_parent(struct basic_block *source, pseudo_t pseudo)
  16 {
  17         /* Can't go upwards if the pseudo is defined in the bb it came from.. */
  18         if (pseudo->type == PSEUDO_REG) {
  19                 struct instruction *def = pseudo->def;
  20                 if (def->bb == source)
  21                         return source;
  22         }
  23         if (bb_list_size(source->children) != 1 || bb_list_size(source->parents) != 1)
  24                 return source;
  25         return first_basic_block(source->parents);
  26 }
  27
  28 static void clear_phi(struct instruction *insn)
  29 {
  30         pseudo_t phi;
  31
  32         insn->bb = NULL;
  33         FOR_EACH_PTR(insn->phi_list, phi) {
  34                 *THIS_ADDRESS(phi) = VOID;
  35         } END_FOR_EACH_PTR(phi);
  36 }
  37
  38 static int if_convert_phi(struct instruction *insn)
  39 {
  40         pseudo_t array[3];
  41         struct basic_block *parents[3];
  42         struct basic_block *bb, *bb1, *bb2, *source;
  43         struct instruction *br;
  44         pseudo_t p1, p2;
  45
  46         bb = insn->bb;
  47         if (linearize_ptr_list((struct ptr_list *)insn->phi_list, (void **)array, 3) != 2)
  48                 return 0;
  49         if (linearize_ptr_list((struct ptr_list *)bb->parents, (void **)parents, 3) != 2)
  50                 return 0;
  51         p1 = array[0]->def->src1;
  52         bb1 = array[0]->def->bb;
  53         p2 = array[1]->def->src1;
  54         bb2 = array[1]->def->bb;
  55
  56         /* Only try the simple "direct parents" case */
  57         if ((bb1 != parents[0] || bb2 != parents[1]) &&
  58             (bb1 != parents[1] || bb2 != parents[0]))
  59                 return 0;
  60
  61         /*
  62          * See if we can find a common source for this..
  63          */
  64         source = phi_parent(bb1, p1);
  65         if (source != phi_parent(bb2, p2))
  66                 return 0;
  67
  68         /*
  69          * Cool. We now know that 'source' is the exclusive
  70          * parent of both phi-nodes, so the exit at the
  71          * end of it fully determines which one it is, and
  72          * we can turn it into a select.
  73          *
  74          * HOWEVER, right now we only handle regular
  75          * conditional branches. No multijumps or computed
  76          * stuff. Verify that here.
  77          */
  78         br = last_instruction(source->insns);
  79         if (!br || br->opcode != OP_BR)
  80                 return 0;
  81
  82         assert(br->cond);
  83         assert(br->bb_false);
  84
  85         /*
  86          * We're in business. Match up true/false with p1/p2.
  87          */
  88         if (br->bb_true == bb2 || br->bb_false == bb1) {
  89                 pseudo_t p = p1;
  90                 p1 = p2;
  91                 p2 = p;
  92         }
  93
  94         /*
  95          * OK, we can now replace that last
  96          *
  97          *      br cond, a, b
  98          *
  99          * with the sequence
 100          *
 101          *      setcc cond
 102          *      select pseudo, p1, p2
 103          *      br cond, a, b
 104          *
 105          * and remove the phi-node. If it then
 106          * turns out that 'a' or 'b' is entirely
 107          * empty (common case), and now no longer
 108          * a phi-source, we'll be able to simplify
 109          * the conditional branch too.
 110          */
 111         insert_select(source, br, insn, p1, p2);
 112         clear_phi(insn);
 113         return REPEAT_CSE;
 114 }
 115
 116 static int clean_up_phi(struct instruction *insn)
 117 {
 118         pseudo_t phi;
 119         struct instruction *last;
 120         int same;
 121
 122         last = NULL;
 123         same = 1;
 124         FOR_EACH_PTR(insn->phi_list, phi) {
 125                 struct instruction *def;
 126                 if (phi == VOID)
 127                         continue;
 128                 def = phi->def;
 129                 if (def->src1 == VOID || !def->bb)
 130                         continue;
 131                 if (last) {
 132                         if (last->src1 != def->src1)
 133                                 same = 0;
 134                         continue;
 135                 }
 136                 last = def;
 137         } END_FOR_EACH_PTR(phi);
 138
 139         if (same) {
 140                 pseudo_t pseudo = last ? last->src1 : VOID;
 141                 convert_instruction_target(insn, pseudo);
 142                 clear_phi(insn);
 143                 return REPEAT_CSE;
 144         }
 145
 146         return if_convert_phi(insn);
 147 }
 148
 149 static int delete_pseudo_user_list_entry(struct pseudo_user_list **list, pseudo_t *entry, int count)
 150 {
 151         struct pseudo_user *pu;
 152
 153         FOR_EACH_PTR(*list, pu) {
 154                 if (pu->userp == entry) {
 155                         DELETE_CURRENT_PTR(pu);
 156                         if (!--count)
 157                                 goto out;
 158                 }
 159         } END_FOR_EACH_PTR(pu);
 160         assert(count <= 0);
 161 out:
 162         pack_ptr_list((struct ptr_list **)list);
 163         return count;
 164 }
 165
 166 static inline void remove_usage(pseudo_t p, pseudo_t *usep)
 167 {
 168         if (has_use_list(p)) {
 169                 delete_pseudo_user_list_entry(&p->users, usep, 1);
 170                 if (!p->users)
 171                         kill_instruction(p->def);
 172         }
 173 }
 174
 175 void kill_use(pseudo_t *usep)
 176 {
 177         if (usep) {
 178                 pseudo_t p = *usep;
 179                 *usep = VOID;
 180                 remove_usage(p, usep);
 181         }
 182 }
 183
 184 void kill_instruction(struct instruction *insn)
 185 {
 186         if (!insn || !insn->bb)
 187                 return;
 188
 189         switch (insn->opcode) {
 190         case OP_BINARY ... OP_BINCMP_END:
 191                 insn->bb = NULL;
 192                 kill_use(&insn->src1);
 193                 kill_use(&insn->src2);
 194                 repeat_phase |= REPEAT_CSE;
 195                 return;
 196
 197         case OP_NOT: case OP_NEG:
 198                 insn->bb = NULL;
 199                 kill_use(&insn->src1);
 200                 repeat_phase |= REPEAT_CSE;
 201                 return;
 202
 203         case OP_PHI:
 204                 insn->bb = NULL;
 205                 repeat_phase |= REPEAT_CSE;
 206                 return;
 207
 208         case OP_SYMADDR:
 209                 insn->bb = NULL;
 210                 repeat_phase |= REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 211                 return;
 212
 213         case OP_RANGE:
 214                 insn->bb = NULL;
 215                 repeat_phase |= REPEAT_CSE;
 216                 kill_use(&insn->src1);
 217                 kill_use(&insn->src2);
 218                 kill_use(&insn->src3);
 219                 return;
 220         case OP_BR:
 221                 insn->bb = NULL;
 222                 repeat_phase |= REPEAT_CSE;
 223                 if (insn->cond)
 224                         kill_use(&insn->cond);
 225                 return;
 226         }
 227 }
 228
 229 /*
 230  * Kill trivially dead instructions
 231  */
 232 static int dead_insn(struct instruction *insn, pseudo_t *src1, pseudo_t *src2, pseudo_t *src3)
 233 {
 234         struct pseudo_user *pu;
 235         FOR_EACH_PTR(insn->target->users, pu) {
 236                 if (*pu->userp != VOID)
 237                         return 0;
 238         } END_FOR_EACH_PTR(pu);
 239
 240         insn->bb = NULL;
 241         kill_use(src1);
 242         kill_use(src2);
 243         kill_use(src3);
 244         return REPEAT_CSE;
 245 }
 246
 247 static inline int constant(pseudo_t pseudo)
 248 {
 249         return pseudo->type == PSEUDO_VAL;
 250 }
 251
 252 static int replace_with_pseudo(struct instruction *insn, pseudo_t pseudo)
 253 {
 254         convert_instruction_target(insn, pseudo);
 255         insn->bb = NULL;
 256         return REPEAT_CSE;
 257 }
 258
 259 static int simplify_constant_rightside(struct instruction *insn)
 260 {
 261         long long value = insn->src2->value;
 262
 263         switch (insn->opcode) {
 264         case OP_SUB:
 265                 if (value) {
 266                         insn->opcode = OP_ADD;
 267                         insn->src2 = value_pseudo(-value);
 268                         return REPEAT_CSE;
 269                 }
 270         /* Fall through */
 271         case OP_ADD:
 272         case OP_OR: case OP_XOR:
 273         case OP_OR_BOOL:
 274         case OP_SHL:
 275         case OP_LSR: case OP_ASR:
 276                 if (!value)
 277                         return replace_with_pseudo(insn, insn->src1);
 278                 return 0;
 279
 280         case OP_MULU: case OP_MULS:
 281         case OP_AND_BOOL:
 282                 if (value == 1)
 283                         return replace_with_pseudo(insn, insn->src1);
 284         /* Fall through */
 285         case OP_AND:
 286                 if (!value)
 287                         return replace_with_pseudo(insn, insn->src2);
 288                 return 0;
 289         }
 290         return 0;
 291 }
 292
 293 static int simplify_constant_leftside(struct instruction *insn)
 294 {
 295         long long value = insn->src1->value;
 296
 297         switch (insn->opcode) {
 298         case OP_ADD: case OP_OR: case OP_XOR:
 299                 if (!value)
 300                         return replace_with_pseudo(insn, insn->src2);
 301                 return 0;
 302
 303         case OP_SHL:
 304         case OP_LSR: case OP_ASR:
 305         case OP_AND:
 306         case OP_MULU: case OP_MULS:
 307                 if (!value)
 308                         return replace_with_pseudo(insn, insn->src1);
 309                 return 0;
 310         }
 311         return 0;
 312 }
 313
 314 static int simplify_constant_binop(struct instruction *insn)
 315 {
 316         /* FIXME! Verify signs and sizes!! */
 317         long long left = insn->src1->value;
 318         long long right = insn->src2->value;
 319         unsigned long long ul, ur;
 320         long long res, mask, bits;
 321
 322         mask = 1ULL << (insn->size-1);
 323         bits = mask | (mask-1);
 324
 325         if (left & mask)
 326                 left |= ~bits;
 327         if (right & mask)
 328                 right |= ~bits;
 329         ul = left & bits;
 330         ur = right & bits;
 331
 332         switch (insn->opcode) {
 333         case OP_ADD:
 334                 res = left + right;
 335                 break;
 336         case OP_SUB:
 337                 res = left - right;
 338                 break;
 339         case OP_MULU:
 340                 res = ul * ur;
 341                 break;
 342         case OP_MULS:
 343                 res = left * right;
 344                 break;
 345         case OP_DIVU:
 346                 if (!ur)
 347                         return 0;
 348                 res = ul / ur;
 349                 break;
 350         case OP_DIVS:
 351                 if (!right)
 352                         return 0;
 353                 res = left / right;
 354                 break;
 355         case OP_MODU:
 356                 if (!ur)
 357                         return 0;
 358                 res = ul % ur;
 359                 break;
 360         case OP_MODS:
 361                 if (!right)
 362                         return 0;
 363                 res = left % right;
 364                 break;
 365         case OP_SHL:
 366                 res = left << right;
 367                 break;
 368         case OP_LSR:
 369                 res = ul >> ur;
 370                 break;
 371         case OP_ASR:
 372                 res = left >> right;
 373                 break;
 374        /* Logical */
 375         case OP_AND:
 376                 res = left & right;
 377                 break;
 378         case OP_OR:
 379                 res = left | right;
 380                 break;
 381         case OP_XOR:
 382                 res = left ^ right;
 383                 break;
 384         case OP_AND_BOOL:
 385                 res = left && right;
 386                 break;
 387         case OP_OR_BOOL:
 388                 res = left || right;
 389                 break;
 390
 391         /* Binary comparison */
 392         case OP_SET_EQ:
 393                 res = left == right;
 394                 break;
 395         case OP_SET_NE:
 396                 res = left != right;
 397                 break;
 398         case OP_SET_LE:
 399                 res = left <= right;
 400                 break;
 401         case OP_SET_GE:
 402                 res = left >= right;
 403                 break;
 404         case OP_SET_LT:
 405                 res = left < right;
 406                 break;
 407         case OP_SET_GT:
 408                 res = left > right;
 409                 break;
 410         case OP_SET_B:
 411                 res = ul < ur;
 412                 break;
 413         case OP_SET_A:
 414                 res = ul > ur;
 415                 break;
 416         case OP_SET_BE:
 417                 res = ul <= ur;
 418                 break;
 419         case OP_SET_AE:
 420                 res = ul >= ur;
 421                 break;
 422         default:
 423                 return 0;
 424         }
 425         res &= bits;
 426
 427         replace_with_pseudo(insn, value_pseudo(res));
 428         return REPEAT_CSE;
 429 }
 430
 431 static int simplify_binop(struct instruction *insn)
 432 {
 433         if (dead_insn(insn, &insn->src1, &insn->src2, NULL))
 434                 return REPEAT_CSE;
 435         if (constant(insn->src1)) {
 436                 if (constant(insn->src2))
 437                         return simplify_constant_binop(insn);
 438                 return simplify_constant_leftside(insn);
 439         }
 440         if (constant(insn->src2))
 441                 return simplify_constant_rightside(insn);
 442         return 0;
 443 }
 444
 445 static void switch_pseudo(struct instruction *insn1, pseudo_t *pp1, struct instruction *insn2, pseudo_t *pp2)
 446 {
 447         pseudo_t p1 = *pp1, p2 = *pp2;
 448
 449         use_pseudo(insn1, p2, pp1);
 450         use_pseudo(insn2, p1, pp2);
 451         remove_usage(p1, pp1);
 452         remove_usage(p2, pp2);
 453 }
 454
 455 static int canonical_order(pseudo_t p1, pseudo_t p2)
 456 {
 457         /* symbol/constants on the right */
 458         if (p1->type == PSEUDO_VAL)
 459                 return p2->type == PSEUDO_VAL;
 460
 461         if (p1->type == PSEUDO_SYM)
 462                 return p2->type == PSEUDO_SYM || p2->type == PSEUDO_VAL;
 463
 464         return 1;
 465 }
 466
 467 static int simplify_commutative_binop(struct instruction *insn)
 468 {
 469         if (!canonical_order(insn->src1, insn->src2)) {
 470                 switch_pseudo(insn, &insn->src1, insn, &insn->src2);
 471                 return REPEAT_CSE;
 472         }
 473         return 0;
 474 }
 475
 476 static inline int simple_pseudo(pseudo_t pseudo)
 477 {
 478         return pseudo->type == PSEUDO_VAL || pseudo->type == PSEUDO_SYM;
 479 }
 480
 481 static int simplify_associative_binop(struct instruction *insn)
 482 {
 483         struct instruction *def;
 484         pseudo_t pseudo = insn->src1;
 485
 486         if (!simple_pseudo(insn->src2))
 487                 return 0;
 488         if (pseudo->type != PSEUDO_REG)
 489                 return 0;
 490         def = pseudo->def;
 491         if (def == insn)
 492                 return 0;
 493         if (def->opcode != insn->opcode)
 494                 return 0;
 495         if (!simple_pseudo(def->src2))
 496                 return 0;
 497         if (ptr_list_size((struct ptr_list *)def->target->users) != 1)
 498                 return 0;
 499         switch_pseudo(def, &def->src1, insn, &insn->src2);
 500         return REPEAT_CSE;
 501 }
 502
 503 static int simplify_constant_unop(struct instruction *insn)
 504 {
 505         long long val = insn->src1->value;
 506         long long res, mask;
 507
 508         switch (insn->opcode) {
 509         case OP_NOT:
 510                 res = ~val;
 511                 break;
 512         case OP_NEG:
 513                 res = -val;
 514                 break;
 515         default:
 516                 return 0;
 517         }
 518         mask = 1ULL << (insn->size-1);
 519         res &= mask | (mask-1);
 520
 521         replace_with_pseudo(insn, value_pseudo(res));
 522         return REPEAT_CSE;
 523 }
 524
 525 static int simplify_unop(struct instruction *insn)
 526 {
 527         if (dead_insn(insn, &insn->src1, NULL, NULL))
 528                 return REPEAT_CSE;
 529         if (constant(insn->src1))
 530                 return simplify_constant_unop(insn);
 531         return 0;
 532 }
 533
 534 static int simplify_one_memop(struct instruction *insn, pseudo_t orig)
 535 {
 536         pseudo_t addr = insn->src;
 537         pseudo_t new, off;
 538
 539         if (addr->type == PSEUDO_REG) {
 540                 struct instruction *def = addr->def;
 541                 if (def->opcode == OP_SYMADDR && def->src) {
 542                         kill_use(&insn->src);
 543                         use_pseudo(insn, def->src, &insn->src);
 544                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 545                 }
 546                 if (def->opcode == OP_ADD) {
 547                         new = def->src1;
 548                         off = def->src2;
 549                         if (constant(off))
 550                                 goto offset;
 551                         new = off;
 552                         off = def->src1;
 553                         if (constant(off))
 554                                 goto offset;
 555                         return 0;
 556                 }
 557         }
 558         return 0;
 559
 560 offset:
 561         /* Invalid code */
 562         if (new == orig) {
 563                 if (new == VOID)
 564                         return 0;
 565                 new = VOID;
 566                 warning(insn->pos, "crazy programmer");
 567         }
 568         insn->offset += off->value;
 569         use_pseudo(insn, new, &insn->src);
 570         remove_usage(addr, &insn->src);
 571         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 572 }
 573
 574 /*
 575  * We walk the whole chain of adds/subs backwards. That's not
 576  * only more efficient, but it allows us to find loops.
 577  */
 578 static int simplify_memop(struct instruction *insn)
 579 {
 580         int one, ret = 0;
 581         pseudo_t orig = insn->src;
 582
 583         do {
 584                 one = simplify_one_memop(insn, orig);
 585                 ret |= one;
 586         } while (one);
 587         return ret;
 588 }
 589
 590 static long long get_cast_value(long long val, int old_size, int new_size, int sign)
 591 {
 592         long long mask;
 593
 594         if (sign && new_size > old_size) {
 595                 mask = 1 << (old_size-1);
 596                 if (val & mask)
 597                         val |= ~(mask | (mask-1));
 598         }
 599         mask = 1 << (new_size-1);
 600         return val & (mask | (mask-1));
 601 }
 602
 603 static int simplify_cast(struct instruction *insn)
 604 {
 605         struct symbol *orig_type;
 606         int orig_size, size;
 607         pseudo_t src;
 608
 609         if (dead_insn(insn, &insn->src, NULL, NULL))
 610                 return REPEAT_CSE;
 611
 612         orig_type = insn->orig_type;
 613         if (!orig_type)
 614                 return 0;
 615         orig_size = orig_type->bit_size;
 616         size = insn->size;
 617         src = insn->src;
 618
 619         /* A cast of a constant? */
 620         if (constant(src)) {
 621                 int sign = orig_type->ctype.modifiers & MOD_SIGNED;
 622                 long long val = get_cast_value(src->value, orig_size, size, sign);
 623                 src = value_pseudo(val);
 624                 goto simplify;
 625         }
 626
 627         /* A cast of a "and" might be a no-op.. */
 628         if (src->type == PSEUDO_REG) {
 629                 struct instruction *def = src->def;
 630                 if (def->opcode == OP_AND && def->size >= size) {
 631                         pseudo_t val = def->src2;
 632                         if (val->type == PSEUDO_VAL) {
 633                                 unsigned long long value = val->value;
 634                                 if (!(value >> (size-1)))
 635                                         goto simplify;
 636                         }
 637                 }
 638         }
 639
 640         if (size == orig_size) {
 641                 int op = (orig_type->ctype.modifiers & MOD_SIGNED) ? OP_SCAST : OP_CAST;
 642                 if (insn->opcode == op)
 643                         goto simplify;
 644         }
 645
 646         return 0;
 647
 648 simplify:
 649         return replace_with_pseudo(insn, src);
 650 }
 651
 652 static int simplify_select(struct instruction *insn)
 653 {
 654         pseudo_t cond, src1, src2;
 655
 656         if (dead_insn(insn, &insn->src1, &insn->src2, &insn->src3))
 657                 return REPEAT_CSE;
 658
 659         cond = insn->src1;
 660         src1 = insn->src2;
 661         src2 = insn->src3;
 662         if (constant(cond) || src1 == src2) {
 663                 pseudo_t *kill, take;
 664                 kill_use(&insn->src1);
 665                 take = cond->value ? src1 : src2;
 666                 kill = cond->value ? &insn->src3 : &insn->src2;
 667                 kill_use(kill);
 668                 replace_with_pseudo(insn, take);
 669                 return REPEAT_CSE;
 670         }
 671         if (constant(src1) && constant(src2)) {
 672                 long long val1 = src1->value;
 673                 long long val2 = src2->value;
 674
 675                 /* The pair 0/1 is special - replace with SETNE/SETEQ */
 676                 if ((val1 | val2) == 1) {
 677                         int opcode = OP_SET_EQ;
 678                         if (val1) {
 679                                 src1 = src2;
 680                                 opcode = OP_SET_NE;
 681                         }
 682                         insn->opcode = opcode;
 683                         /* insn->src1 is already cond */
 684                         insn->src2 = src1; /* Zero */
 685                         return REPEAT_CSE;
 686                 }
 687         }
 688         return 0;
 689 }
 690
 691 static int is_in_range(pseudo_t src, long long low, long long high)
 692 {
 693         long long value;
 694
 695         switch (src->type) {
 696         case PSEUDO_VAL:
 697                 value = src->value;
 698                 return value >= low && value <= high;
 699         default:
 700                 return 0;
 701         }
 702 }
 703
 704 static int simplify_range(struct instruction *insn)
 705 {
 706         pseudo_t src1, src2, src3;
 707
 708         src1 = insn->src1;
 709         src2 = insn->src2;
 710         src3 = insn->src3;
 711         if (src2->type != PSEUDO_VAL || src3->type != PSEUDO_VAL)
 712                 return 0;
 713         if (is_in_range(src1, src2->value, src3->value)) {
 714                 kill_instruction(insn);
 715                 return REPEAT_CSE;
 716         }
 717         return 0;
 718 }
 719
 720 /*
 721  * Simplify "set_ne/eq $0 + br"
 722  */
 723 static int simplify_cond_branch(struct instruction *br, pseudo_t cond, struct instruction *def, pseudo_t *pp)
 724 {
 725         use_pseudo(br, *pp, &br->cond);
 726         remove_usage(cond, &br->cond);
 727         if (def->opcode == OP_SET_EQ) {
 728                 struct basic_block *true = br->bb_true;
 729                 struct basic_block *false = br->bb_false;
 730                 br->bb_false = true;
 731                 br->bb_true = false;
 732         }
 733         return REPEAT_CSE;
 734 }
 735
 736 static int simplify_branch(struct instruction *insn)
 737 {
 738         pseudo_t cond = insn->cond;
 739
 740         if (!cond)
 741                 return 0;
 742
 743         /* Constant conditional */
 744         if (constant(cond)) {
 745                 insert_branch(insn->bb, insn, cond->value ? insn->bb_true : insn->bb_false);
 746                 return REPEAT_CSE;
 747         }
 748
 749         /* Same target? */
 750         if (insn->bb_true == insn->bb_false) {
 751                 struct basic_block *bb = insn->bb;
 752                 struct basic_block *target = insn->bb_false;
 753                 remove_bb_from_list(&target->parents, bb, 1);
 754                 remove_bb_from_list(&bb->children, target, 1);
 755                 insn->bb_false = NULL;
 756                 kill_use(&insn->cond);
 757                 insn->cond = NULL;
 758                 return REPEAT_CSE;
 759         }
 760
 761         /* Conditional on a SETNE $0 or SETEQ $0 */
 762         if (cond->type == PSEUDO_REG) {
 763                 struct instruction *def = cond->def;
 764
 765                 if (def->opcode == OP_SET_NE || def->opcode == OP_SET_EQ) {
 766                         if (constant(def->src1) && !def->src1->value)
 767                                 return simplify_cond_branch(insn, cond, def, &def->src2);
 768                         if (constant(def->src2) && !def->src2->value)
 769                                 return simplify_cond_branch(insn, cond, def, &def->src1);
 770                 }
 771                 if (def->opcode == OP_SEL) {
 772                         if (constant(def->src2) && constant(def->src3)) {
 773                                 long long val1 = def->src2->value;
 774                                 long long val2 = def->src3->value;
 775                                 if (!val1 && !val2) {
 776                                         insert_branch(insn->bb, insn, insn->bb_false);
 777                                         return REPEAT_CSE;
 778                                 }
 779                                 if (val1 && val2) {
 780                                         insert_branch(insn->bb, insn, insn->bb_true);
 781                                         return REPEAT_CSE;
 782                                 }
 783                                 if (val2) {
 784                                         struct basic_block *true = insn->bb_true;
 785                                         struct basic_block *false = insn->bb_false;
 786                                         insn->bb_false = true;
 787                                         insn->bb_true = false;
 788                                 }
 789                                 use_pseudo(insn, def->src1, &insn->cond);
 790                                 remove_usage(cond, &insn->cond);
 791                                 return REPEAT_CSE;
 792                         }
 793                 }
 794                 if (def->opcode == OP_CAST || def->opcode == OP_SCAST) {
 795                         int orig_size = def->orig_type ? def->orig_type->bit_size : 0;
 796                         if (def->size > orig_size) {
 797                                 use_pseudo(insn, def->src, &insn->cond);
 798                                 remove_usage(cond, &insn->cond);
 799                                 return REPEAT_CSE;
 800                         }
 801                 }
 802         }
 803         return 0;
 804 }
 805
 806 static int simplify_switch(struct instruction *insn)
 807 {
 808         pseudo_t cond = insn->cond;
 809         long long val;
 810         struct multijmp *jmp;
 811
 812         if (!constant(cond))
 813                 return 0;
 814         val = insn->cond->value;
 815
 816         FOR_EACH_PTR(insn->multijmp_list, jmp) {
 817                 /* Default case */
 818                 if (jmp->begin > jmp->end)
 819                         goto found;
 820                 if (val >= jmp->begin && val <= jmp->end)
 821                         goto found;
 822         } END_FOR_EACH_PTR(jmp);
 823         warning(insn->pos, "Impossible case statement");
 824         return 0;
 825
 826 found:
 827         insert_branch(insn->bb, insn, jmp->target);
 828         return REPEAT_CSE;
 829 }
 830
 831 int simplify_instruction(struct instruction *insn)
 832 {
 833         if (!insn->bb)
 834                 return 0;
 835         switch (insn->opcode) {
 836         case OP_ADD: case OP_MULS:
 837         case OP_AND: case OP_OR: case OP_XOR:
 838         case OP_AND_BOOL: case OP_OR_BOOL:
 839                 if (simplify_binop(insn))
 840                         return REPEAT_CSE;
 841                 if (simplify_commutative_binop(insn))
 842                         return REPEAT_CSE;
 843                 return simplify_associative_binop(insn);
 844
 845         case OP_MULU:
 846         case OP_SET_EQ: case OP_SET_NE:
 847                 if (simplify_binop(insn))
 848                         return REPEAT_CSE;
 849                 return simplify_commutative_binop(insn);
 850
 851         case OP_SUB:
 852         case OP_DIVU: case OP_DIVS:
 853         case OP_MODU: case OP_MODS:
 854         case OP_SHL:
 855         case OP_LSR: case OP_ASR:
 856         case OP_SET_LE: case OP_SET_GE:
 857         case OP_SET_LT: case OP_SET_GT:
 858         case OP_SET_B:  case OP_SET_A:
 859         case OP_SET_BE: case OP_SET_AE:
 860                 return simplify_binop(insn);
 861
 862         case OP_NOT: case OP_NEG:
 863                 return simplify_unop(insn);
 864         case OP_LOAD: case OP_STORE:
 865                 return simplify_memop(insn);
 866         case OP_SYMADDR:
 867                 if (dead_insn(insn, NULL, NULL, NULL))
 868                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 869                 return replace_with_pseudo(insn, insn->symbol);
 870         case OP_CAST:
 871         case OP_SCAST:
 872         case OP_FPCAST:
 873         case OP_PTRCAST:
 874                 return simplify_cast(insn);
 875         case OP_PHI:
 876                 if (dead_insn(insn, NULL, NULL, NULL)) {
 877                         clear_phi(insn);
 878                         return REPEAT_CSE;
 879                 }
 880                 return clean_up_phi(insn);
 881         case OP_PHISOURCE:
 882                 if (dead_insn(insn, &insn->phi_src, NULL, NULL))
 883                         return REPEAT_CSE;
 884                 break;
 885         case OP_SEL:
 886                 return simplify_select(insn);
 887         case OP_BR:
 888                 return simplify_branch(insn);
 889         case OP_SWITCH:
 890                 return simplify_switch(insn);
 891         case OP_RANGE:
 892                 return simplify_range(insn);
 893         }
 894         return 0;
 895 }