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 #include "symbol.h"
  14
  15 /* Find the trivial parent for a phi-source */
  16 static struct basic_block *phi_parent(struct basic_block *source, pseudo_t pseudo)
  17 {
  18         /* Can't go upwards if the pseudo is defined in the bb it came from.. */
  19         if (pseudo->type == PSEUDO_REG) {
  20                 struct instruction *def = pseudo->def;
  21                 if (def->bb == source)
  22                         return source;
  23         }
  24         if (bb_list_size(source->children) != 1 || bb_list_size(source->parents) != 1)
  25                 return source;
  26         return first_basic_block(source->parents);
  27 }
  28
  29 static void clear_phi(struct instruction *insn)
  30 {
  31         pseudo_t phi;
  32
  33         insn->bb = NULL;
  34         FOR_EACH_PTR(insn->phi_list, phi) {
  35                 *THIS_ADDRESS(phi) = VOID;
  36         } END_FOR_EACH_PTR(phi);
  37 }
  38
  39 static int if_convert_phi(struct instruction *insn)
  40 {
  41         pseudo_t array[3];
  42         struct basic_block *parents[3];
  43         struct basic_block *bb, *bb1, *bb2, *source;
  44         struct instruction *br;
  45         pseudo_t p1, p2;
  46
  47         bb = insn->bb;
  48         if (linearize_ptr_list((struct ptr_list *)insn->phi_list, (void **)array, 3) != 2)
  49                 return 0;
  50         if (linearize_ptr_list((struct ptr_list *)bb->parents, (void **)parents, 3) != 2)
  51                 return 0;
  52         p1 = array[0]->def->src1;
  53         bb1 = array[0]->def->bb;
  54         p2 = array[1]->def->src1;
  55         bb2 = array[1]->def->bb;
  56
  57         /* Only try the simple "direct parents" case */
  58         if ((bb1 != parents[0] || bb2 != parents[1]) &&
  59             (bb1 != parents[1] || bb2 != parents[0]))
  60                 return 0;
  61
  62         /*
  63          * See if we can find a common source for this..
  64          */
  65         source = phi_parent(bb1, p1);
  66         if (source != phi_parent(bb2, p2))
  67                 return 0;
  68
  69         /*
  70          * Cool. We now know that 'source' is the exclusive
  71          * parent of both phi-nodes, so the exit at the
  72          * end of it fully determines which one it is, and
  73          * we can turn it into a select.
  74          *
  75          * HOWEVER, right now we only handle regular
  76          * conditional branches. No multijumps or computed
  77          * stuff. Verify that here.
  78          */
  79         br = last_instruction(source->insns);
  80         if (!br || br->opcode != OP_BR)
  81                 return 0;
  82
  83         assert(br->cond);
  84         assert(br->bb_false);
  85
  86         /*
  87          * We're in business. Match up true/false with p1/p2.
  88          */
  89         if (br->bb_true == bb2 || br->bb_false == bb1) {
  90                 pseudo_t p = p1;
  91                 p1 = p2;
  92                 p2 = p;
  93         }
  94
  95         /*
  96          * OK, we can now replace that last
  97          *
  98          *      br cond, a, b
  99          *
 100          * with the sequence
 101          *
 102          *      setcc cond
 103          *      select pseudo, p1, p2
 104          *      br cond, a, b
 105          *
 106          * and remove the phi-node. If it then
 107          * turns out that 'a' or 'b' is entirely
 108          * empty (common case), and now no longer
 109          * a phi-source, we'll be able to simplify
 110          * the conditional branch too.
 111          */
 112         insert_select(source, br, insn, p1, p2);
 113         clear_phi(insn);
 114         return REPEAT_CSE;
 115 }
 116
 117 static int clean_up_phi(struct instruction *insn)
 118 {
 119         pseudo_t phi;
 120         struct instruction *last;
 121         int same;
 122
 123         last = NULL;
 124         same = 1;
 125         FOR_EACH_PTR(insn->phi_list, phi) {
 126                 struct instruction *def;
 127                 if (phi == VOID)
 128                         continue;
 129                 def = phi->def;
 130                 if (def->src1 == VOID || !def->bb)
 131                         continue;
 132                 if (last) {
 133                         if (last->src1 != def->src1)
 134                                 same = 0;
 135                         continue;
 136                 }
 137                 last = def;
 138         } END_FOR_EACH_PTR(phi);
 139
 140         if (same) {
 141                 pseudo_t pseudo = last ? last->src1 : VOID;
 142                 convert_instruction_target(insn, pseudo);
 143                 clear_phi(insn);
 144                 return REPEAT_CSE;
 145         }
 146
 147         return if_convert_phi(insn);
 148 }
 149
 150 static int delete_pseudo_user_list_entry(struct pseudo_user_list **list, pseudo_t *entry, int count)
 151 {
 152         struct pseudo_user *pu;
 153
 154         FOR_EACH_PTR(*list, pu) {
 155                 if (pu->userp == entry) {
 156                         DELETE_CURRENT_PTR(pu);
 157                         if (!--count)
 158                                 goto out;
 159                 }
 160         } END_FOR_EACH_PTR(pu);
 161         assert(count <= 0);
 162 out:
 163         pack_ptr_list((struct ptr_list **)list);
 164         return count;
 165 }
 166
 167 static inline void remove_usage(pseudo_t p, pseudo_t *usep)
 168 {
 169         if (has_use_list(p)) {
 170                 delete_pseudo_user_list_entry(&p->users, usep, 1);
 171                 if (!p->users)
 172                         kill_instruction(p->def);
 173         }
 174 }
 175
 176 void kill_use(pseudo_t *usep)
 177 {
 178         if (usep) {
 179                 pseudo_t p = *usep;
 180                 *usep = VOID;
 181                 remove_usage(p, usep);
 182         }
 183 }
 184
 185 void kill_instruction(struct instruction *insn)
 186 {
 187         if (!insn || !insn->bb)
 188                 return;
 189
 190         switch (insn->opcode) {
 191         case OP_SEL:
 192         case OP_RANGE:
 193                 kill_use(&insn->src3);
 194                 /* fall through */
 195
 196         case OP_BINARY ... OP_BINCMP_END:
 197                 kill_use(&insn->src2);
 198                 /* fall through */
 199
 200         case OP_CAST:
 201         case OP_SCAST:
 202         case OP_FPCAST:
 203         case OP_PTRCAST:
 204         case OP_SETVAL:
 205         case OP_NOT: case OP_NEG:
 206                 kill_use(&insn->src1);
 207                 break;
 208
 209         case OP_PHI:
 210                 clear_phi(insn);
 211                 break;
 212
 213         case OP_SYMADDR:
 214                 repeat_phase |= REPEAT_SYMBOL_CLEANUP;
 215                 break;
 216
 217         case OP_BR:
 218                 if (!insn->bb_true || !insn->bb_false)
 219                         break;
 220                 /* fall through */
 221
 222         case OP_COMPUTEDGOTO:
 223                 kill_use(&insn->cond);
 224                 break;
 225
 226         case OP_ENTRY:
 227         default:
 228                 /* ignore */
 229                 return;
 230         }
 231
 232         insn->bb = NULL;
 233         repeat_phase |= REPEAT_CSE;
 234         return;
 235 }
 236
 237 /*
 238  * Kill trivially dead instructions
 239  */
 240 static int dead_insn(struct instruction *insn, pseudo_t *src1, pseudo_t *src2, pseudo_t *src3)
 241 {
 242         struct pseudo_user *pu;
 243         FOR_EACH_PTR(insn->target->users, pu) {
 244                 if (*pu->userp != VOID)
 245                         return 0;
 246         } END_FOR_EACH_PTR(pu);
 247
 248         insn->bb = NULL;
 249         kill_use(src1);
 250         kill_use(src2);
 251         kill_use(src3);
 252         return REPEAT_CSE;
 253 }
 254
 255 static inline int constant(pseudo_t pseudo)
 256 {
 257         return pseudo->type == PSEUDO_VAL;
 258 }
 259
 260 static int replace_with_pseudo(struct instruction *insn, pseudo_t pseudo)
 261 {
 262         convert_instruction_target(insn, pseudo);
 263
 264         switch (insn->opcode) {
 265         case OP_SEL:
 266         case OP_RANGE:
 267                 kill_use(&insn->src3);
 268         case OP_BINARY ... OP_BINCMP_END:
 269                 kill_use(&insn->src2);
 270         case OP_NOT:
 271         case OP_NEG:
 272         case OP_SYMADDR:
 273         case OP_CAST:
 274         case OP_SCAST:
 275         case OP_FPCAST:
 276         case OP_PTRCAST:
 277                 kill_use(&insn->src1);
 278                 break;
 279
 280         default:
 281                 assert(0);
 282         }
 283         insn->bb = NULL;
 284         return REPEAT_CSE;
 285 }
 286
 287 static unsigned int value_size(long long value)
 288 {
 289         value >>= 8;
 290         if (!value)
 291                 return 8;
 292         value >>= 8;
 293         if (!value)
 294                 return 16;
 295         value >>= 16;
 296         if (!value)
 297                 return 32;
 298         return 64;
 299 }
 300
 301 /*
 302  * Try to determine the maximum size of bits in a pseudo.
 303  *
 304  * Right now this only follow casts and constant values, but we
 305  * could look at things like logical 'and' instructions etc.
 306  */
 307 static unsigned int operand_size(struct instruction *insn, pseudo_t pseudo)
 308 {
 309         unsigned int size = insn->size;
 310
 311         if (pseudo->type == PSEUDO_REG) {
 312                 struct instruction *src = pseudo->def;
 313                 if (src && src->opcode == OP_CAST && src->orig_type) {
 314                         unsigned int orig_size = src->orig_type->bit_size;
 315                         if (orig_size < size)
 316                                 size = orig_size;
 317                 }
 318         }
 319         if (pseudo->type == PSEUDO_VAL) {
 320                 unsigned int orig_size = value_size(pseudo->value);
 321                 if (orig_size < size)
 322                         size = orig_size;
 323         }
 324         return size;
 325 }
 326
 327 static int simplify_asr(struct instruction *insn, pseudo_t pseudo, long long value)
 328 {
 329         unsigned int size = operand_size(insn, pseudo);
 330
 331         if (value >= size) {
 332                 warning(insn->pos, "right shift by bigger than source value");
 333                 return replace_with_pseudo(insn, value_pseudo(0));
 334         }
 335         if (!value)
 336                 return replace_with_pseudo(insn, pseudo);
 337         return 0;
 338 }
 339
 340 static int simplify_mul_div(struct instruction *insn, long long value)
 341 {
 342         unsigned long long sbit = 1ULL << (insn->size - 1);
 343         unsigned long long bits = sbit | (sbit - 1);
 344
 345         if (value == 1)
 346                 return replace_with_pseudo(insn, insn->src1);
 347
 348         switch (insn->opcode) {
 349         case OP_MULS:
 350         case OP_MULU:
 351                 if (value == 0)
 352                         return replace_with_pseudo(insn, insn->src2);
 353         /* Fall through */
 354         case OP_DIVS:
 355                 if (!(value & sbit))    // positive
 356                         break;
 357
 358                 value |= ~bits;
 359                 if (value == -1) {
 360                         insn->opcode = OP_NEG;
 361                         return REPEAT_CSE;
 362                 }
 363         }
 364
 365         return 0;
 366 }
 367
 368 static int simplify_constant_rightside(struct instruction *insn)
 369 {
 370         long long value = insn->src2->value;
 371
 372         switch (insn->opcode) {
 373         case OP_SUB:
 374                 if (value) {
 375                         insn->opcode = OP_ADD;
 376                         insn->src2 = value_pseudo(-value);
 377                         return REPEAT_CSE;
 378                 }
 379         /* Fall through */
 380         case OP_ADD:
 381         case OP_OR: case OP_XOR:
 382         case OP_OR_BOOL:
 383         case OP_SHL:
 384         case OP_LSR:
 385                 if (!value)
 386                         return replace_with_pseudo(insn, insn->src1);
 387                 return 0;
 388         case OP_ASR:
 389                 return simplify_asr(insn, insn->src1, value);
 390
 391         case OP_DIVU: case OP_DIVS:
 392         case OP_MULU: case OP_MULS:
 393                 return simplify_mul_div(insn, value);
 394
 395         case OP_AND_BOOL:
 396                 if (value == 1)
 397                         return replace_with_pseudo(insn, insn->src1);
 398         /* Fall through */
 399         case OP_AND:
 400                 if (!value)
 401                         return replace_with_pseudo(insn, insn->src2);
 402                 return 0;
 403         }
 404         return 0;
 405 }
 406
 407 static int simplify_constant_leftside(struct instruction *insn)
 408 {
 409         long long value = insn->src1->value;
 410
 411         switch (insn->opcode) {
 412         case OP_ADD: case OP_OR: case OP_XOR:
 413                 if (!value)
 414                         return replace_with_pseudo(insn, insn->src2);
 415                 return 0;
 416
 417         case OP_SHL:
 418         case OP_LSR: case OP_ASR:
 419         case OP_AND:
 420         case OP_MULU: case OP_MULS:
 421                 if (!value)
 422                         return replace_with_pseudo(insn, insn->src1);
 423                 return 0;
 424         }
 425         return 0;
 426 }
 427
 428 static int simplify_constant_binop(struct instruction *insn)
 429 {
 430         /* FIXME! Verify signs and sizes!! */
 431         long long left = insn->src1->value;
 432         long long right = insn->src2->value;
 433         unsigned long long ul, ur;
 434         long long res, mask, bits;
 435
 436         mask = 1ULL << (insn->size-1);
 437         bits = mask | (mask-1);
 438
 439         if (left & mask)
 440                 left |= ~bits;
 441         if (right & mask)
 442                 right |= ~bits;
 443         ul = left & bits;
 444         ur = right & bits;
 445
 446         switch (insn->opcode) {
 447         case OP_ADD:
 448                 res = left + right;
 449                 break;
 450         case OP_SUB:
 451                 res = left - right;
 452                 break;
 453         case OP_MULU:
 454                 res = ul * ur;
 455                 break;
 456         case OP_MULS:
 457                 res = left * right;
 458                 break;
 459         case OP_DIVU:
 460                 if (!ur)
 461                         return 0;
 462                 res = ul / ur;
 463                 break;
 464         case OP_DIVS:
 465                 if (!right)
 466                         return 0;
 467                 if (left == mask && right == -1)
 468                         return 0;
 469                 res = left / right;
 470                 break;
 471         case OP_MODU:
 472                 if (!ur)
 473                         return 0;
 474                 res = ul % ur;
 475                 break;
 476         case OP_MODS:
 477                 if (!right)
 478                         return 0;
 479                 if (left == mask && right == -1)
 480                         return 0;
 481                 res = left % right;
 482                 break;
 483         case OP_SHL:
 484                 res = left << right;
 485                 break;
 486         case OP_LSR:
 487                 res = ul >> ur;
 488                 break;
 489         case OP_ASR:
 490                 res = left >> right;
 491                 break;
 492        /* Logical */
 493         case OP_AND:
 494                 res = left & right;
 495                 break;
 496         case OP_OR:
 497                 res = left | right;
 498                 break;
 499         case OP_XOR:
 500                 res = left ^ right;
 501                 break;
 502         case OP_AND_BOOL:
 503                 res = left && right;
 504                 break;
 505         case OP_OR_BOOL:
 506                 res = left || right;
 507                 break;
 508
 509         /* Binary comparison */
 510         case OP_SET_EQ:
 511                 res = left == right;
 512                 break;
 513         case OP_SET_NE:
 514                 res = left != right;
 515                 break;
 516         case OP_SET_LE:
 517                 res = left <= right;
 518                 break;
 519         case OP_SET_GE:
 520                 res = left >= right;
 521                 break;
 522         case OP_SET_LT:
 523                 res = left < right;
 524                 break;
 525         case OP_SET_GT:
 526                 res = left > right;
 527                 break;
 528         case OP_SET_B:
 529                 res = ul < ur;
 530                 break;
 531         case OP_SET_A:
 532                 res = ul > ur;
 533                 break;
 534         case OP_SET_BE:
 535                 res = ul <= ur;
 536                 break;
 537         case OP_SET_AE:
 538                 res = ul >= ur;
 539                 break;
 540         default:
 541                 return 0;
 542         }
 543         res &= bits;
 544
 545         replace_with_pseudo(insn, value_pseudo(res));
 546         return REPEAT_CSE;
 547 }
 548
 549 static int simplify_binop(struct instruction *insn)
 550 {
 551         if (dead_insn(insn, &insn->src1, &insn->src2, NULL))
 552                 return REPEAT_CSE;
 553         if (constant(insn->src1)) {
 554                 if (constant(insn->src2))
 555                         return simplify_constant_binop(insn);
 556                 return simplify_constant_leftside(insn);
 557         }
 558         if (constant(insn->src2))
 559                 return simplify_constant_rightside(insn);
 560         return 0;
 561 }
 562
 563 static void switch_pseudo(struct instruction *insn1, pseudo_t *pp1, struct instruction *insn2, pseudo_t *pp2)
 564 {
 565         pseudo_t p1 = *pp1, p2 = *pp2;
 566
 567         use_pseudo(insn1, p2, pp1);
 568         use_pseudo(insn2, p1, pp2);
 569         remove_usage(p1, pp1);
 570         remove_usage(p2, pp2);
 571 }
 572
 573 static int canonical_order(pseudo_t p1, pseudo_t p2)
 574 {
 575         /* symbol/constants on the right */
 576         if (p1->type == PSEUDO_VAL)
 577                 return p2->type == PSEUDO_VAL;
 578
 579         if (p1->type == PSEUDO_SYM)
 580                 return p2->type == PSEUDO_SYM || p2->type == PSEUDO_VAL;
 581
 582         return 1;
 583 }
 584
 585 static int simplify_commutative_binop(struct instruction *insn)
 586 {
 587         if (!canonical_order(insn->src1, insn->src2)) {
 588                 switch_pseudo(insn, &insn->src1, insn, &insn->src2);
 589                 return REPEAT_CSE;
 590         }
 591         return 0;
 592 }
 593
 594 static inline int simple_pseudo(pseudo_t pseudo)
 595 {
 596         return pseudo->type == PSEUDO_VAL || pseudo->type == PSEUDO_SYM;
 597 }
 598
 599 static int simplify_associative_binop(struct instruction *insn)
 600 {
 601         struct instruction *def;
 602         pseudo_t pseudo = insn->src1;
 603
 604         if (!simple_pseudo(insn->src2))
 605                 return 0;
 606         if (pseudo->type != PSEUDO_REG)
 607                 return 0;
 608         def = pseudo->def;
 609         if (def == insn)
 610                 return 0;
 611         if (def->opcode != insn->opcode)
 612                 return 0;
 613         if (!simple_pseudo(def->src2))
 614                 return 0;
 615         if (ptr_list_size((struct ptr_list *)def->target->users) != 1)
 616                 return 0;
 617         switch_pseudo(def, &def->src1, insn, &insn->src2);
 618         return REPEAT_CSE;
 619 }
 620
 621 static int simplify_constant_unop(struct instruction *insn)
 622 {
 623         long long val = insn->src1->value;
 624         long long res, mask;
 625
 626         switch (insn->opcode) {
 627         case OP_NOT:
 628                 res = ~val;
 629                 break;
 630         case OP_NEG:
 631                 res = -val;
 632                 break;
 633         default:
 634                 return 0;
 635         }
 636         mask = 1ULL << (insn->size-1);
 637         res &= mask | (mask-1);
 638
 639         replace_with_pseudo(insn, value_pseudo(res));
 640         return REPEAT_CSE;
 641 }
 642
 643 static int simplify_unop(struct instruction *insn)
 644 {
 645         if (dead_insn(insn, &insn->src1, NULL, NULL))
 646                 return REPEAT_CSE;
 647         if (constant(insn->src1))
 648                 return simplify_constant_unop(insn);
 649         return 0;
 650 }
 651
 652 static int simplify_one_memop(struct instruction *insn, pseudo_t orig)
 653 {
 654         pseudo_t addr = insn->src;
 655         pseudo_t new, off;
 656
 657         if (addr->type == PSEUDO_REG) {
 658                 struct instruction *def = addr->def;
 659                 if (def->opcode == OP_SYMADDR && def->src) {
 660                         kill_use(&insn->src);
 661                         use_pseudo(insn, def->src, &insn->src);
 662                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 663                 }
 664                 if (def->opcode == OP_ADD) {
 665                         new = def->src1;
 666                         off = def->src2;
 667                         if (constant(off))
 668                                 goto offset;
 669                         new = off;
 670                         off = def->src1;
 671                         if (constant(off))
 672                                 goto offset;
 673                         return 0;
 674                 }
 675         }
 676         return 0;
 677
 678 offset:
 679         /* Invalid code */
 680         if (new == orig) {
 681                 if (new == VOID)
 682                         return 0;
 683                 new = VOID;
 684                 warning(insn->pos, "crazy programmer");
 685         }
 686         insn->offset += off->value;
 687         use_pseudo(insn, new, &insn->src);
 688         remove_usage(addr, &insn->src);
 689         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 690 }
 691
 692 /*
 693  * We walk the whole chain of adds/subs backwards. That's not
 694  * only more efficient, but it allows us to find loops.
 695  */
 696 static int simplify_memop(struct instruction *insn)
 697 {
 698         int one, ret = 0;
 699         pseudo_t orig = insn->src;
 700
 701         do {
 702                 one = simplify_one_memop(insn, orig);
 703                 ret |= one;
 704         } while (one);
 705         return ret;
 706 }
 707
 708 static long long get_cast_value(long long val, int old_size, int new_size, int sign)
 709 {
 710         long long mask;
 711
 712         if (sign && new_size > old_size) {
 713                 mask = 1 << (old_size-1);
 714                 if (val & mask)
 715                         val |= ~(mask | (mask-1));
 716         }
 717         mask = 1 << (new_size-1);
 718         return val & (mask | (mask-1));
 719 }
 720
 721 static int simplify_cast(struct instruction *insn)
 722 {
 723         struct symbol *orig_type;
 724         int orig_size, size;
 725         pseudo_t src;
 726
 727         if (dead_insn(insn, &insn->src, NULL, NULL))
 728                 return REPEAT_CSE;
 729
 730         orig_type = insn->orig_type;
 731         if (!orig_type)
 732                 return 0;
 733
 734         /* Keep casts with pointer on either side (not only case of OP_PTRCAST) */
 735         if (is_ptr_type(orig_type) || is_ptr_type(insn->type))
 736                 return 0;
 737
 738         orig_size = orig_type->bit_size;
 739         size = insn->size;
 740         src = insn->src;
 741
 742         /* A cast of a constant? */
 743         if (constant(src)) {
 744                 int sign = orig_type->ctype.modifiers & MOD_SIGNED;
 745                 long long val = get_cast_value(src->value, orig_size, size, sign);
 746                 src = value_pseudo(val);
 747                 goto simplify;
 748         }
 749
 750         /* A cast of a "and" might be a no-op.. */
 751         if (src->type == PSEUDO_REG) {
 752                 struct instruction *def = src->def;
 753                 if (def->opcode == OP_AND && def->size >= size) {
 754                         pseudo_t val = def->src2;
 755                         if (val->type == PSEUDO_VAL) {
 756                                 unsigned long long value = val->value;
 757                                 if (!(value >> (size-1)))
 758                                         goto simplify;
 759                         }
 760                 }
 761         }
 762
 763         if (size == orig_size) {
 764                 int op = (orig_type->ctype.modifiers & MOD_SIGNED) ? OP_SCAST : OP_CAST;
 765                 if (insn->opcode == op)
 766                         goto simplify;
 767         }
 768
 769         return 0;
 770
 771 simplify:
 772         return replace_with_pseudo(insn, src);
 773 }
 774
 775 static int simplify_select(struct instruction *insn)
 776 {
 777         pseudo_t cond, src1, src2;
 778
 779         if (dead_insn(insn, &insn->src1, &insn->src2, &insn->src3))
 780                 return REPEAT_CSE;
 781
 782         cond = insn->src1;
 783         src1 = insn->src2;
 784         src2 = insn->src3;
 785         if (constant(cond) || src1 == src2) {
 786                 pseudo_t *kill, take;
 787                 kill_use(&insn->src1);
 788                 take = cond->value ? src1 : src2;
 789                 kill = cond->value ? &insn->src3 : &insn->src2;
 790                 kill_use(kill);
 791                 replace_with_pseudo(insn, take);
 792                 return REPEAT_CSE;
 793         }
 794         if (constant(src1) && constant(src2)) {
 795                 long long val1 = src1->value;
 796                 long long val2 = src2->value;
 797
 798                 /* The pair 0/1 is special - replace with SETNE/SETEQ */
 799                 if ((val1 | val2) == 1) {
 800                         int opcode = OP_SET_EQ;
 801                         if (val1) {
 802                                 src1 = src2;
 803                                 opcode = OP_SET_NE;
 804                         }
 805                         insn->opcode = opcode;
 806                         /* insn->src1 is already cond */
 807                         insn->src2 = src1; /* Zero */
 808                         return REPEAT_CSE;
 809                 }
 810         }
 811         return 0;
 812 }
 813
 814 static int is_in_range(pseudo_t src, long long low, long long high)
 815 {
 816         long long value;
 817
 818         switch (src->type) {
 819         case PSEUDO_VAL:
 820                 value = src->value;
 821                 return value >= low && value <= high;
 822         default:
 823                 return 0;
 824         }
 825 }
 826
 827 static int simplify_range(struct instruction *insn)
 828 {
 829         pseudo_t src1, src2, src3;
 830
 831         src1 = insn->src1;
 832         src2 = insn->src2;
 833         src3 = insn->src3;
 834         if (src2->type != PSEUDO_VAL || src3->type != PSEUDO_VAL)
 835                 return 0;
 836         if (is_in_range(src1, src2->value, src3->value)) {
 837                 kill_instruction(insn);
 838                 return REPEAT_CSE;
 839         }
 840         return 0;
 841 }
 842
 843 /*
 844  * Simplify "set_ne/eq $0 + br"
 845  */
 846 static int simplify_cond_branch(struct instruction *br, pseudo_t cond, struct instruction *def, pseudo_t *pp)
 847 {
 848         use_pseudo(br, *pp, &br->cond);
 849         remove_usage(cond, &br->cond);
 850         if (def->opcode == OP_SET_EQ) {
 851                 struct basic_block *true = br->bb_true;
 852                 struct basic_block *false = br->bb_false;
 853                 br->bb_false = true;
 854                 br->bb_true = false;
 855         }
 856         return REPEAT_CSE;
 857 }
 858
 859 static int simplify_branch(struct instruction *insn)
 860 {
 861         pseudo_t cond = insn->cond;
 862
 863         if (!cond)
 864                 return 0;
 865
 866         /* Constant conditional */
 867         if (constant(cond)) {
 868                 insert_branch(insn->bb, insn, cond->value ? insn->bb_true : insn->bb_false);
 869                 return REPEAT_CSE;
 870         }
 871
 872         /* Same target? */
 873         if (insn->bb_true == insn->bb_false) {
 874                 struct basic_block *bb = insn->bb;
 875                 struct basic_block *target = insn->bb_false;
 876                 remove_bb_from_list(&target->parents, bb, 1);
 877                 remove_bb_from_list(&bb->children, target, 1);
 878                 insn->bb_false = NULL;
 879                 kill_use(&insn->cond);
 880                 insn->cond = NULL;
 881                 return REPEAT_CSE;
 882         }
 883
 884         /* Conditional on a SETNE $0 or SETEQ $0 */
 885         if (cond->type == PSEUDO_REG) {
 886                 struct instruction *def = cond->def;
 887
 888                 if (def->opcode == OP_SET_NE || def->opcode == OP_SET_EQ) {
 889                         if (constant(def->src1) && !def->src1->value)
 890                                 return simplify_cond_branch(insn, cond, def, &def->src2);
 891                         if (constant(def->src2) && !def->src2->value)
 892                                 return simplify_cond_branch(insn, cond, def, &def->src1);
 893                 }
 894                 if (def->opcode == OP_SEL) {
 895                         if (constant(def->src2) && constant(def->src3)) {
 896                                 long long val1 = def->src2->value;
 897                                 long long val2 = def->src3->value;
 898                                 if (!val1 && !val2) {
 899                                         insert_branch(insn->bb, insn, insn->bb_false);
 900                                         return REPEAT_CSE;
 901                                 }
 902                                 if (val1 && val2) {
 903                                         insert_branch(insn->bb, insn, insn->bb_true);
 904                                         return REPEAT_CSE;
 905                                 }
 906                                 if (val2) {
 907                                         struct basic_block *true = insn->bb_true;
 908                                         struct basic_block *false = insn->bb_false;
 909                                         insn->bb_false = true;
 910                                         insn->bb_true = false;
 911                                 }
 912                                 use_pseudo(insn, def->src1, &insn->cond);
 913                                 remove_usage(cond, &insn->cond);
 914                                 return REPEAT_CSE;
 915                         }
 916                 }
 917                 if (def->opcode == OP_CAST || def->opcode == OP_SCAST) {
 918                         int orig_size = def->orig_type ? def->orig_type->bit_size : 0;
 919                         if (def->size > orig_size) {
 920                                 use_pseudo(insn, def->src, &insn->cond);
 921                                 remove_usage(cond, &insn->cond);
 922                                 return REPEAT_CSE;
 923                         }
 924                 }
 925         }
 926         return 0;
 927 }
 928
 929 static int simplify_switch(struct instruction *insn)
 930 {
 931         pseudo_t cond = insn->cond;
 932         long long val;
 933         struct multijmp *jmp;
 934
 935         if (!constant(cond))
 936                 return 0;
 937         val = insn->cond->value;
 938
 939         FOR_EACH_PTR(insn->multijmp_list, jmp) {
 940                 /* Default case */
 941                 if (jmp->begin > jmp->end)
 942                         goto found;
 943                 if (val >= jmp->begin && val <= jmp->end)
 944                         goto found;
 945         } END_FOR_EACH_PTR(jmp);
 946         warning(insn->pos, "Impossible case statement");
 947         return 0;
 948
 949 found:
 950         insert_branch(insn->bb, insn, jmp->target);
 951         return REPEAT_CSE;
 952 }
 953
 954 int simplify_instruction(struct instruction *insn)
 955 {
 956         if (!insn->bb)
 957                 return 0;
 958         switch (insn->opcode) {
 959         case OP_ADD: case OP_MULS:
 960         case OP_AND: case OP_OR: case OP_XOR:
 961         case OP_AND_BOOL: case OP_OR_BOOL:
 962                 if (simplify_binop(insn))
 963                         return REPEAT_CSE;
 964                 if (simplify_commutative_binop(insn))
 965                         return REPEAT_CSE;
 966                 return simplify_associative_binop(insn);
 967
 968         case OP_MULU:
 969         case OP_SET_EQ: case OP_SET_NE:
 970                 if (simplify_binop(insn))
 971                         return REPEAT_CSE;
 972                 return simplify_commutative_binop(insn);
 973
 974         case OP_SUB:
 975         case OP_DIVU: case OP_DIVS:
 976         case OP_MODU: case OP_MODS:
 977         case OP_SHL:
 978         case OP_LSR: case OP_ASR:
 979         case OP_SET_LE: case OP_SET_GE:
 980         case OP_SET_LT: case OP_SET_GT:
 981         case OP_SET_B:  case OP_SET_A:
 982         case OP_SET_BE: case OP_SET_AE:
 983                 return simplify_binop(insn);
 984
 985         case OP_NOT: case OP_NEG:
 986                 return simplify_unop(insn);
 987         case OP_LOAD: case OP_STORE:
 988                 return simplify_memop(insn);
 989         case OP_SYMADDR:
 990                 if (dead_insn(insn, NULL, NULL, NULL))
 991                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 992                 return replace_with_pseudo(insn, insn->symbol);
 993         case OP_CAST:
 994         case OP_SCAST:
 995         case OP_FPCAST:
 996         case OP_PTRCAST:
 997                 return simplify_cast(insn);
 998         case OP_PHI:
 999                 if (dead_insn(insn, NULL, NULL, NULL)) {
1000                         clear_phi(insn);
1001                         return REPEAT_CSE;
1002                 }
1003                 return clean_up_phi(insn);
1004         case OP_PHISOURCE:
1005                 if (dead_insn(insn, &insn->phi_src, NULL, NULL))
1006                         return REPEAT_CSE;
1007                 break;
1008         case OP_SEL:
1009                 return simplify_select(insn);
1010         case OP_BR:
1011                 return simplify_branch(insn);
1012         case OP_SWITCH:
1013                 return simplify_switch(insn);
1014         case OP_RANGE:
1015                 return simplify_range(insn);
1016         }
1017         return 0;
1018 }