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         if (value == 1)
 343                 return replace_with_pseudo(insn, insn->src1);
 344
 345         switch (insn->opcode) {
 346         case OP_MULS:
 347         case OP_MULU:
 348                 if (value == 0)
 349                         return replace_with_pseudo(insn, insn->src2);
 350         }
 351
 352         return 0;
 353 }
 354
 355 static int simplify_constant_rightside(struct instruction *insn)
 356 {
 357         long long value = insn->src2->value;
 358
 359         switch (insn->opcode) {
 360         case OP_SUB:
 361                 if (value) {
 362                         insn->opcode = OP_ADD;
 363                         insn->src2 = value_pseudo(-value);
 364                         return REPEAT_CSE;
 365                 }
 366         /* Fall through */
 367         case OP_ADD:
 368         case OP_OR: case OP_XOR:
 369         case OP_OR_BOOL:
 370         case OP_SHL:
 371         case OP_LSR:
 372                 if (!value)
 373                         return replace_with_pseudo(insn, insn->src1);
 374                 return 0;
 375         case OP_ASR:
 376                 return simplify_asr(insn, insn->src1, value);
 377
 378         case OP_DIVU: case OP_DIVS:
 379         case OP_MULU: case OP_MULS:
 380                 return simplify_mul_div(insn, value);
 381
 382         case OP_AND_BOOL:
 383                 if (value == 1)
 384                         return replace_with_pseudo(insn, insn->src1);
 385         /* Fall through */
 386         case OP_AND:
 387                 if (!value)
 388                         return replace_with_pseudo(insn, insn->src2);
 389                 return 0;
 390         }
 391         return 0;
 392 }
 393
 394 static int simplify_constant_leftside(struct instruction *insn)
 395 {
 396         long long value = insn->src1->value;
 397
 398         switch (insn->opcode) {
 399         case OP_ADD: case OP_OR: case OP_XOR:
 400                 if (!value)
 401                         return replace_with_pseudo(insn, insn->src2);
 402                 return 0;
 403
 404         case OP_SHL:
 405         case OP_LSR: case OP_ASR:
 406         case OP_AND:
 407         case OP_MULU: case OP_MULS:
 408                 if (!value)
 409                         return replace_with_pseudo(insn, insn->src1);
 410                 return 0;
 411         }
 412         return 0;
 413 }
 414
 415 static int simplify_constant_binop(struct instruction *insn)
 416 {
 417         /* FIXME! Verify signs and sizes!! */
 418         long long left = insn->src1->value;
 419         long long right = insn->src2->value;
 420         unsigned long long ul, ur;
 421         long long res, mask, bits;
 422
 423         mask = 1ULL << (insn->size-1);
 424         bits = mask | (mask-1);
 425
 426         if (left & mask)
 427                 left |= ~bits;
 428         if (right & mask)
 429                 right |= ~bits;
 430         ul = left & bits;
 431         ur = right & bits;
 432
 433         switch (insn->opcode) {
 434         case OP_ADD:
 435                 res = left + right;
 436                 break;
 437         case OP_SUB:
 438                 res = left - right;
 439                 break;
 440         case OP_MULU:
 441                 res = ul * ur;
 442                 break;
 443         case OP_MULS:
 444                 res = left * right;
 445                 break;
 446         case OP_DIVU:
 447                 if (!ur)
 448                         return 0;
 449                 res = ul / ur;
 450                 break;
 451         case OP_DIVS:
 452                 if (!right)
 453                         return 0;
 454                 if (left == mask && right == -1)
 455                         return 0;
 456                 res = left / right;
 457                 break;
 458         case OP_MODU:
 459                 if (!ur)
 460                         return 0;
 461                 res = ul % ur;
 462                 break;
 463         case OP_MODS:
 464                 if (!right)
 465                         return 0;
 466                 if (left == mask && right == -1)
 467                         return 0;
 468                 res = left % right;
 469                 break;
 470         case OP_SHL:
 471                 res = left << right;
 472                 break;
 473         case OP_LSR:
 474                 res = ul >> ur;
 475                 break;
 476         case OP_ASR:
 477                 res = left >> right;
 478                 break;
 479        /* Logical */
 480         case OP_AND:
 481                 res = left & right;
 482                 break;
 483         case OP_OR:
 484                 res = left | right;
 485                 break;
 486         case OP_XOR:
 487                 res = left ^ right;
 488                 break;
 489         case OP_AND_BOOL:
 490                 res = left && right;
 491                 break;
 492         case OP_OR_BOOL:
 493                 res = left || right;
 494                 break;
 495
 496         /* Binary comparison */
 497         case OP_SET_EQ:
 498                 res = left == right;
 499                 break;
 500         case OP_SET_NE:
 501                 res = left != right;
 502                 break;
 503         case OP_SET_LE:
 504                 res = left <= right;
 505                 break;
 506         case OP_SET_GE:
 507                 res = left >= right;
 508                 break;
 509         case OP_SET_LT:
 510                 res = left < right;
 511                 break;
 512         case OP_SET_GT:
 513                 res = left > right;
 514                 break;
 515         case OP_SET_B:
 516                 res = ul < ur;
 517                 break;
 518         case OP_SET_A:
 519                 res = ul > ur;
 520                 break;
 521         case OP_SET_BE:
 522                 res = ul <= ur;
 523                 break;
 524         case OP_SET_AE:
 525                 res = ul >= ur;
 526                 break;
 527         default:
 528                 return 0;
 529         }
 530         res &= bits;
 531
 532         replace_with_pseudo(insn, value_pseudo(res));
 533         return REPEAT_CSE;
 534 }
 535
 536 static int simplify_binop(struct instruction *insn)
 537 {
 538         if (dead_insn(insn, &insn->src1, &insn->src2, NULL))
 539                 return REPEAT_CSE;
 540         if (constant(insn->src1)) {
 541                 if (constant(insn->src2))
 542                         return simplify_constant_binop(insn);
 543                 return simplify_constant_leftside(insn);
 544         }
 545         if (constant(insn->src2))
 546                 return simplify_constant_rightside(insn);
 547         return 0;
 548 }
 549
 550 static void switch_pseudo(struct instruction *insn1, pseudo_t *pp1, struct instruction *insn2, pseudo_t *pp2)
 551 {
 552         pseudo_t p1 = *pp1, p2 = *pp2;
 553
 554         use_pseudo(insn1, p2, pp1);
 555         use_pseudo(insn2, p1, pp2);
 556         remove_usage(p1, pp1);
 557         remove_usage(p2, pp2);
 558 }
 559
 560 static int canonical_order(pseudo_t p1, pseudo_t p2)
 561 {
 562         /* symbol/constants on the right */
 563         if (p1->type == PSEUDO_VAL)
 564                 return p2->type == PSEUDO_VAL;
 565
 566         if (p1->type == PSEUDO_SYM)
 567                 return p2->type == PSEUDO_SYM || p2->type == PSEUDO_VAL;
 568
 569         return 1;
 570 }
 571
 572 static int simplify_commutative_binop(struct instruction *insn)
 573 {
 574         if (!canonical_order(insn->src1, insn->src2)) {
 575                 switch_pseudo(insn, &insn->src1, insn, &insn->src2);
 576                 return REPEAT_CSE;
 577         }
 578         return 0;
 579 }
 580
 581 static inline int simple_pseudo(pseudo_t pseudo)
 582 {
 583         return pseudo->type == PSEUDO_VAL || pseudo->type == PSEUDO_SYM;
 584 }
 585
 586 static int simplify_associative_binop(struct instruction *insn)
 587 {
 588         struct instruction *def;
 589         pseudo_t pseudo = insn->src1;
 590
 591         if (!simple_pseudo(insn->src2))
 592                 return 0;
 593         if (pseudo->type != PSEUDO_REG)
 594                 return 0;
 595         def = pseudo->def;
 596         if (def == insn)
 597                 return 0;
 598         if (def->opcode != insn->opcode)
 599                 return 0;
 600         if (!simple_pseudo(def->src2))
 601                 return 0;
 602         if (ptr_list_size((struct ptr_list *)def->target->users) != 1)
 603                 return 0;
 604         switch_pseudo(def, &def->src1, insn, &insn->src2);
 605         return REPEAT_CSE;
 606 }
 607
 608 static int simplify_constant_unop(struct instruction *insn)
 609 {
 610         long long val = insn->src1->value;
 611         long long res, mask;
 612
 613         switch (insn->opcode) {
 614         case OP_NOT:
 615                 res = ~val;
 616                 break;
 617         case OP_NEG:
 618                 res = -val;
 619                 break;
 620         default:
 621                 return 0;
 622         }
 623         mask = 1ULL << (insn->size-1);
 624         res &= mask | (mask-1);
 625
 626         replace_with_pseudo(insn, value_pseudo(res));
 627         return REPEAT_CSE;
 628 }
 629
 630 static int simplify_unop(struct instruction *insn)
 631 {
 632         if (dead_insn(insn, &insn->src1, NULL, NULL))
 633                 return REPEAT_CSE;
 634         if (constant(insn->src1))
 635                 return simplify_constant_unop(insn);
 636         return 0;
 637 }
 638
 639 static int simplify_one_memop(struct instruction *insn, pseudo_t orig)
 640 {
 641         pseudo_t addr = insn->src;
 642         pseudo_t new, off;
 643
 644         if (addr->type == PSEUDO_REG) {
 645                 struct instruction *def = addr->def;
 646                 if (def->opcode == OP_SYMADDR && def->src) {
 647                         kill_use(&insn->src);
 648                         use_pseudo(insn, def->src, &insn->src);
 649                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 650                 }
 651                 if (def->opcode == OP_ADD) {
 652                         new = def->src1;
 653                         off = def->src2;
 654                         if (constant(off))
 655                                 goto offset;
 656                         new = off;
 657                         off = def->src1;
 658                         if (constant(off))
 659                                 goto offset;
 660                         return 0;
 661                 }
 662         }
 663         return 0;
 664
 665 offset:
 666         /* Invalid code */
 667         if (new == orig) {
 668                 if (new == VOID)
 669                         return 0;
 670                 new = VOID;
 671                 warning(insn->pos, "crazy programmer");
 672         }
 673         insn->offset += off->value;
 674         use_pseudo(insn, new, &insn->src);
 675         remove_usage(addr, &insn->src);
 676         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 677 }
 678
 679 /*
 680  * We walk the whole chain of adds/subs backwards. That's not
 681  * only more efficient, but it allows us to find loops.
 682  */
 683 static int simplify_memop(struct instruction *insn)
 684 {
 685         int one, ret = 0;
 686         pseudo_t orig = insn->src;
 687
 688         do {
 689                 one = simplify_one_memop(insn, orig);
 690                 ret |= one;
 691         } while (one);
 692         return ret;
 693 }
 694
 695 static long long get_cast_value(long long val, int old_size, int new_size, int sign)
 696 {
 697         long long mask;
 698
 699         if (sign && new_size > old_size) {
 700                 mask = 1 << (old_size-1);
 701                 if (val & mask)
 702                         val |= ~(mask | (mask-1));
 703         }
 704         mask = 1 << (new_size-1);
 705         return val & (mask | (mask-1));
 706 }
 707
 708 static int simplify_cast(struct instruction *insn)
 709 {
 710         struct symbol *orig_type;
 711         int orig_size, size;
 712         pseudo_t src;
 713
 714         if (dead_insn(insn, &insn->src, NULL, NULL))
 715                 return REPEAT_CSE;
 716
 717         orig_type = insn->orig_type;
 718         if (!orig_type)
 719                 return 0;
 720
 721         /* Keep casts with pointer on either side (not only case of OP_PTRCAST) */
 722         if (is_ptr_type(orig_type) || is_ptr_type(insn->type))
 723                 return 0;
 724
 725         orig_size = orig_type->bit_size;
 726         size = insn->size;
 727         src = insn->src;
 728
 729         /* A cast of a constant? */
 730         if (constant(src)) {
 731                 int sign = orig_type->ctype.modifiers & MOD_SIGNED;
 732                 long long val = get_cast_value(src->value, orig_size, size, sign);
 733                 src = value_pseudo(val);
 734                 goto simplify;
 735         }
 736
 737         /* A cast of a "and" might be a no-op.. */
 738         if (src->type == PSEUDO_REG) {
 739                 struct instruction *def = src->def;
 740                 if (def->opcode == OP_AND && def->size >= size) {
 741                         pseudo_t val = def->src2;
 742                         if (val->type == PSEUDO_VAL) {
 743                                 unsigned long long value = val->value;
 744                                 if (!(value >> (size-1)))
 745                                         goto simplify;
 746                         }
 747                 }
 748         }
 749
 750         if (size == orig_size) {
 751                 int op = (orig_type->ctype.modifiers & MOD_SIGNED) ? OP_SCAST : OP_CAST;
 752                 if (insn->opcode == op)
 753                         goto simplify;
 754         }
 755
 756         return 0;
 757
 758 simplify:
 759         return replace_with_pseudo(insn, src);
 760 }
 761
 762 static int simplify_select(struct instruction *insn)
 763 {
 764         pseudo_t cond, src1, src2;
 765
 766         if (dead_insn(insn, &insn->src1, &insn->src2, &insn->src3))
 767                 return REPEAT_CSE;
 768
 769         cond = insn->src1;
 770         src1 = insn->src2;
 771         src2 = insn->src3;
 772         if (constant(cond) || src1 == src2) {
 773                 pseudo_t *kill, take;
 774                 kill_use(&insn->src1);
 775                 take = cond->value ? src1 : src2;
 776                 kill = cond->value ? &insn->src3 : &insn->src2;
 777                 kill_use(kill);
 778                 replace_with_pseudo(insn, take);
 779                 return REPEAT_CSE;
 780         }
 781         if (constant(src1) && constant(src2)) {
 782                 long long val1 = src1->value;
 783                 long long val2 = src2->value;
 784
 785                 /* The pair 0/1 is special - replace with SETNE/SETEQ */
 786                 if ((val1 | val2) == 1) {
 787                         int opcode = OP_SET_EQ;
 788                         if (val1) {
 789                                 src1 = src2;
 790                                 opcode = OP_SET_NE;
 791                         }
 792                         insn->opcode = opcode;
 793                         /* insn->src1 is already cond */
 794                         insn->src2 = src1; /* Zero */
 795                         return REPEAT_CSE;
 796                 }
 797         }
 798         return 0;
 799 }
 800
 801 static int is_in_range(pseudo_t src, long long low, long long high)
 802 {
 803         long long value;
 804
 805         switch (src->type) {
 806         case PSEUDO_VAL:
 807                 value = src->value;
 808                 return value >= low && value <= high;
 809         default:
 810                 return 0;
 811         }
 812 }
 813
 814 static int simplify_range(struct instruction *insn)
 815 {
 816         pseudo_t src1, src2, src3;
 817
 818         src1 = insn->src1;
 819         src2 = insn->src2;
 820         src3 = insn->src3;
 821         if (src2->type != PSEUDO_VAL || src3->type != PSEUDO_VAL)
 822                 return 0;
 823         if (is_in_range(src1, src2->value, src3->value)) {
 824                 kill_instruction(insn);
 825                 return REPEAT_CSE;
 826         }
 827         return 0;
 828 }
 829
 830 /*
 831  * Simplify "set_ne/eq $0 + br"
 832  */
 833 static int simplify_cond_branch(struct instruction *br, pseudo_t cond, struct instruction *def, pseudo_t *pp)
 834 {
 835         use_pseudo(br, *pp, &br->cond);
 836         remove_usage(cond, &br->cond);
 837         if (def->opcode == OP_SET_EQ) {
 838                 struct basic_block *true = br->bb_true;
 839                 struct basic_block *false = br->bb_false;
 840                 br->bb_false = true;
 841                 br->bb_true = false;
 842         }
 843         return REPEAT_CSE;
 844 }
 845
 846 static int simplify_branch(struct instruction *insn)
 847 {
 848         pseudo_t cond = insn->cond;
 849
 850         if (!cond)
 851                 return 0;
 852
 853         /* Constant conditional */
 854         if (constant(cond)) {
 855                 insert_branch(insn->bb, insn, cond->value ? insn->bb_true : insn->bb_false);
 856                 return REPEAT_CSE;
 857         }
 858
 859         /* Same target? */
 860         if (insn->bb_true == insn->bb_false) {
 861                 struct basic_block *bb = insn->bb;
 862                 struct basic_block *target = insn->bb_false;
 863                 remove_bb_from_list(&target->parents, bb, 1);
 864                 remove_bb_from_list(&bb->children, target, 1);
 865                 insn->bb_false = NULL;
 866                 kill_use(&insn->cond);
 867                 insn->cond = NULL;
 868                 return REPEAT_CSE;
 869         }
 870
 871         /* Conditional on a SETNE $0 or SETEQ $0 */
 872         if (cond->type == PSEUDO_REG) {
 873                 struct instruction *def = cond->def;
 874
 875                 if (def->opcode == OP_SET_NE || def->opcode == OP_SET_EQ) {
 876                         if (constant(def->src1) && !def->src1->value)
 877                                 return simplify_cond_branch(insn, cond, def, &def->src2);
 878                         if (constant(def->src2) && !def->src2->value)
 879                                 return simplify_cond_branch(insn, cond, def, &def->src1);
 880                 }
 881                 if (def->opcode == OP_SEL) {
 882                         if (constant(def->src2) && constant(def->src3)) {
 883                                 long long val1 = def->src2->value;
 884                                 long long val2 = def->src3->value;
 885                                 if (!val1 && !val2) {
 886                                         insert_branch(insn->bb, insn, insn->bb_false);
 887                                         return REPEAT_CSE;
 888                                 }
 889                                 if (val1 && val2) {
 890                                         insert_branch(insn->bb, insn, insn->bb_true);
 891                                         return REPEAT_CSE;
 892                                 }
 893                                 if (val2) {
 894                                         struct basic_block *true = insn->bb_true;
 895                                         struct basic_block *false = insn->bb_false;
 896                                         insn->bb_false = true;
 897                                         insn->bb_true = false;
 898                                 }
 899                                 use_pseudo(insn, def->src1, &insn->cond);
 900                                 remove_usage(cond, &insn->cond);
 901                                 return REPEAT_CSE;
 902                         }
 903                 }
 904                 if (def->opcode == OP_CAST || def->opcode == OP_SCAST) {
 905                         int orig_size = def->orig_type ? def->orig_type->bit_size : 0;
 906                         if (def->size > orig_size) {
 907                                 use_pseudo(insn, def->src, &insn->cond);
 908                                 remove_usage(cond, &insn->cond);
 909                                 return REPEAT_CSE;
 910                         }
 911                 }
 912         }
 913         return 0;
 914 }
 915
 916 static int simplify_switch(struct instruction *insn)
 917 {
 918         pseudo_t cond = insn->cond;
 919         long long val;
 920         struct multijmp *jmp;
 921
 922         if (!constant(cond))
 923                 return 0;
 924         val = insn->cond->value;
 925
 926         FOR_EACH_PTR(insn->multijmp_list, jmp) {
 927                 /* Default case */
 928                 if (jmp->begin > jmp->end)
 929                         goto found;
 930                 if (val >= jmp->begin && val <= jmp->end)
 931                         goto found;
 932         } END_FOR_EACH_PTR(jmp);
 933         warning(insn->pos, "Impossible case statement");
 934         return 0;
 935
 936 found:
 937         insert_branch(insn->bb, insn, jmp->target);
 938         return REPEAT_CSE;
 939 }
 940
 941 int simplify_instruction(struct instruction *insn)
 942 {
 943         if (!insn->bb)
 944                 return 0;
 945         switch (insn->opcode) {
 946         case OP_ADD: case OP_MULS:
 947         case OP_AND: case OP_OR: case OP_XOR:
 948         case OP_AND_BOOL: case OP_OR_BOOL:
 949                 if (simplify_binop(insn))
 950                         return REPEAT_CSE;
 951                 if (simplify_commutative_binop(insn))
 952                         return REPEAT_CSE;
 953                 return simplify_associative_binop(insn);
 954
 955         case OP_MULU:
 956         case OP_SET_EQ: case OP_SET_NE:
 957                 if (simplify_binop(insn))
 958                         return REPEAT_CSE;
 959                 return simplify_commutative_binop(insn);
 960
 961         case OP_SUB:
 962         case OP_DIVU: case OP_DIVS:
 963         case OP_MODU: case OP_MODS:
 964         case OP_SHL:
 965         case OP_LSR: case OP_ASR:
 966         case OP_SET_LE: case OP_SET_GE:
 967         case OP_SET_LT: case OP_SET_GT:
 968         case OP_SET_B:  case OP_SET_A:
 969         case OP_SET_BE: case OP_SET_AE:
 970                 return simplify_binop(insn);
 971
 972         case OP_NOT: case OP_NEG:
 973                 return simplify_unop(insn);
 974         case OP_LOAD: case OP_STORE:
 975                 return simplify_memop(insn);
 976         case OP_SYMADDR:
 977                 if (dead_insn(insn, NULL, NULL, NULL))
 978                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 979                 return replace_with_pseudo(insn, insn->symbol);
 980         case OP_CAST:
 981         case OP_SCAST:
 982         case OP_FPCAST:
 983         case OP_PTRCAST:
 984                 return simplify_cast(insn);
 985         case OP_PHI:
 986                 if (dead_insn(insn, NULL, NULL, NULL)) {
 987                         clear_phi(insn);
 988                         return REPEAT_CSE;
 989                 }
 990                 return clean_up_phi(insn);
 991         case OP_PHISOURCE:
 992                 if (dead_insn(insn, &insn->phi_src, NULL, NULL))
 993                         return REPEAT_CSE;
 994                 break;
 995         case OP_SEL:
 996                 return simplify_select(insn);
 997         case OP_BR:
 998                 return simplify_branch(insn);
 999         case OP_SWITCH:
1000                 return simplify_switch(insn);
1001         case OP_RANGE:
1002                 return simplify_range(insn);
1003         }
1004         return 0;
1005 }