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