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_NOT: case OP_NEG:
 205                 kill_use(&insn->src1);
 206                 break;
 207
 208         case OP_PHI:
 209                 clear_phi(insn);
 210                 break;
 211
 212         case OP_SYMADDR:
 213                 repeat_phase |= REPEAT_SYMBOL_CLEANUP;
 214                 break;
 215
 216         case OP_BR:
 217                 if (!insn->bb_true || !insn->bb_false)
 218                         break;
 219                 /* fall through */
 220
 221         case OP_COMPUTEDGOTO:
 222                 kill_use(&insn->cond);
 223                 break;
 224
 225         case OP_ENTRY:
 226         default:
 227                 /* ignore */
 228                 return;
 229         }
 230
 231         insn->bb = NULL;
 232         repeat_phase |= REPEAT_CSE;
 233         return;
 234 }
 235
 236 /*
 237  * Kill trivially dead instructions
 238  */
 239 static int dead_insn(struct instruction *insn, pseudo_t *src1, pseudo_t *src2, pseudo_t *src3)
 240 {
 241         struct pseudo_user *pu;
 242         FOR_EACH_PTR(insn->target->users, pu) {
 243                 if (*pu->userp != VOID)
 244                         return 0;
 245         } END_FOR_EACH_PTR(pu);
 246
 247         insn->bb = NULL;
 248         kill_use(src1);
 249         kill_use(src2);
 250         kill_use(src3);
 251         return REPEAT_CSE;
 252 }
 253
 254 static inline int constant(pseudo_t pseudo)
 255 {
 256         return pseudo->type == PSEUDO_VAL;
 257 }
 258
 259 static int replace_with_pseudo(struct instruction *insn, pseudo_t pseudo)
 260 {
 261         convert_instruction_target(insn, pseudo);
 262
 263         switch (insn->opcode) {
 264         case OP_SEL:
 265         case OP_RANGE:
 266                 kill_use(&insn->src3);
 267         case OP_BINARY ... OP_BINCMP_END:
 268                 kill_use(&insn->src2);
 269         case OP_NOT:
 270         case OP_NEG:
 271         case OP_SYMADDR:
 272         case OP_CAST:
 273         case OP_SCAST:
 274         case OP_FPCAST:
 275         case OP_PTRCAST:
 276                 kill_use(&insn->src1);
 277                 break;
 278
 279         default:
 280                 assert(0);
 281         }
 282         insn->bb = NULL;
 283         return REPEAT_CSE;
 284 }
 285
 286 static unsigned int value_size(long long value)
 287 {
 288         value >>= 8;
 289         if (!value)
 290                 return 8;
 291         value >>= 8;
 292         if (!value)
 293                 return 16;
 294         value >>= 16;
 295         if (!value)
 296                 return 32;
 297         return 64;
 298 }
 299
 300 /*
 301  * Try to determine the maximum size of bits in a pseudo.
 302  *
 303  * Right now this only follow casts and constant values, but we
 304  * could look at things like logical 'and' instructions etc.
 305  */
 306 static unsigned int operand_size(struct instruction *insn, pseudo_t pseudo)
 307 {
 308         unsigned int size = insn->size;
 309
 310         if (pseudo->type == PSEUDO_REG) {
 311                 struct instruction *src = pseudo->def;
 312                 if (src && src->opcode == OP_CAST && src->orig_type) {
 313                         unsigned int orig_size = src->orig_type->bit_size;
 314                         if (orig_size < size)
 315                                 size = orig_size;
 316                 }
 317         }
 318         if (pseudo->type == PSEUDO_VAL) {
 319                 unsigned int orig_size = value_size(pseudo->value);
 320                 if (orig_size < size)
 321                         size = orig_size;
 322         }
 323         return size;
 324 }
 325
 326 static int simplify_asr(struct instruction *insn, pseudo_t pseudo, long long value)
 327 {
 328         unsigned int size = operand_size(insn, pseudo);
 329
 330         if (value >= size) {
 331                 warning(insn->pos, "right shift by bigger than source value");
 332                 return replace_with_pseudo(insn, value_pseudo(0));
 333         }
 334         if (!value)
 335                 return replace_with_pseudo(insn, pseudo);
 336         return 0;
 337 }
 338
 339 static int simplify_constant_rightside(struct instruction *insn)
 340 {
 341         long long value = insn->src2->value;
 342
 343         switch (insn->opcode) {
 344         case OP_SUB:
 345                 if (value) {
 346                         insn->opcode = OP_ADD;
 347                         insn->src2 = value_pseudo(-value);
 348                         return REPEAT_CSE;
 349                 }
 350         /* Fall through */
 351         case OP_ADD:
 352         case OP_OR: case OP_XOR:
 353         case OP_OR_BOOL:
 354         case OP_SHL:
 355         case OP_LSR:
 356                 if (!value)
 357                         return replace_with_pseudo(insn, insn->src1);
 358                 return 0;
 359         case OP_ASR:
 360                 return simplify_asr(insn, insn->src1, value);
 361
 362         case OP_MULU: case OP_MULS:
 363         case OP_AND_BOOL:
 364                 if (value == 1)
 365                         return replace_with_pseudo(insn, insn->src1);
 366         /* Fall through */
 367         case OP_AND:
 368                 if (!value)
 369                         return replace_with_pseudo(insn, insn->src2);
 370                 return 0;
 371         }
 372         return 0;
 373 }
 374
 375 static int simplify_constant_leftside(struct instruction *insn)
 376 {
 377         long long value = insn->src1->value;
 378
 379         switch (insn->opcode) {
 380         case OP_ADD: case OP_OR: case OP_XOR:
 381                 if (!value)
 382                         return replace_with_pseudo(insn, insn->src2);
 383                 return 0;
 384
 385         case OP_SHL:
 386         case OP_LSR: case OP_ASR:
 387         case OP_AND:
 388         case OP_MULU: case OP_MULS:
 389                 if (!value)
 390                         return replace_with_pseudo(insn, insn->src1);
 391                 return 0;
 392         }
 393         return 0;
 394 }
 395
 396 static int simplify_constant_binop(struct instruction *insn)
 397 {
 398         /* FIXME! Verify signs and sizes!! */
 399         long long left = insn->src1->value;
 400         long long right = insn->src2->value;
 401         unsigned long long ul, ur;
 402         long long res, mask, bits;
 403
 404         mask = 1ULL << (insn->size-1);
 405         bits = mask | (mask-1);
 406
 407         if (left & mask)
 408                 left |= ~bits;
 409         if (right & mask)
 410                 right |= ~bits;
 411         ul = left & bits;
 412         ur = right & bits;
 413
 414         switch (insn->opcode) {
 415         case OP_ADD:
 416                 res = left + right;
 417                 break;
 418         case OP_SUB:
 419                 res = left - right;
 420                 break;
 421         case OP_MULU:
 422                 res = ul * ur;
 423                 break;
 424         case OP_MULS:
 425                 res = left * right;
 426                 break;
 427         case OP_DIVU:
 428                 if (!ur)
 429                         return 0;
 430                 res = ul / ur;
 431                 break;
 432         case OP_DIVS:
 433                 if (!right)
 434                         return 0;
 435                 if (left == mask && right == -1)
 436                         return 0;
 437                 res = left / right;
 438                 break;
 439         case OP_MODU:
 440                 if (!ur)
 441                         return 0;
 442                 res = ul % ur;
 443                 break;
 444         case OP_MODS:
 445                 if (!right)
 446                         return 0;
 447                 if (left == mask && right == -1)
 448                         return 0;
 449                 res = left % right;
 450                 break;
 451         case OP_SHL:
 452                 res = left << right;
 453                 break;
 454         case OP_LSR:
 455                 res = ul >> ur;
 456                 break;
 457         case OP_ASR:
 458                 res = left >> right;
 459                 break;
 460        /* Logical */
 461         case OP_AND:
 462                 res = left & right;
 463                 break;
 464         case OP_OR:
 465                 res = left | right;
 466                 break;
 467         case OP_XOR:
 468                 res = left ^ right;
 469                 break;
 470         case OP_AND_BOOL:
 471                 res = left && right;
 472                 break;
 473         case OP_OR_BOOL:
 474                 res = left || right;
 475                 break;
 476
 477         /* Binary comparison */
 478         case OP_SET_EQ:
 479                 res = left == right;
 480                 break;
 481         case OP_SET_NE:
 482                 res = left != right;
 483                 break;
 484         case OP_SET_LE:
 485                 res = left <= right;
 486                 break;
 487         case OP_SET_GE:
 488                 res = left >= right;
 489                 break;
 490         case OP_SET_LT:
 491                 res = left < right;
 492                 break;
 493         case OP_SET_GT:
 494                 res = left > right;
 495                 break;
 496         case OP_SET_B:
 497                 res = ul < ur;
 498                 break;
 499         case OP_SET_A:
 500                 res = ul > ur;
 501                 break;
 502         case OP_SET_BE:
 503                 res = ul <= ur;
 504                 break;
 505         case OP_SET_AE:
 506                 res = ul >= ur;
 507                 break;
 508         default:
 509                 return 0;
 510         }
 511         res &= bits;
 512
 513         replace_with_pseudo(insn, value_pseudo(res));
 514         return REPEAT_CSE;
 515 }
 516
 517 static int simplify_binop(struct instruction *insn)
 518 {
 519         if (dead_insn(insn, &insn->src1, &insn->src2, NULL))
 520                 return REPEAT_CSE;
 521         if (constant(insn->src1)) {
 522                 if (constant(insn->src2))
 523                         return simplify_constant_binop(insn);
 524                 return simplify_constant_leftside(insn);
 525         }
 526         if (constant(insn->src2))
 527                 return simplify_constant_rightside(insn);
 528         return 0;
 529 }
 530
 531 static void switch_pseudo(struct instruction *insn1, pseudo_t *pp1, struct instruction *insn2, pseudo_t *pp2)
 532 {
 533         pseudo_t p1 = *pp1, p2 = *pp2;
 534
 535         use_pseudo(insn1, p2, pp1);
 536         use_pseudo(insn2, p1, pp2);
 537         remove_usage(p1, pp1);
 538         remove_usage(p2, pp2);
 539 }
 540
 541 static int canonical_order(pseudo_t p1, pseudo_t p2)
 542 {
 543         /* symbol/constants on the right */
 544         if (p1->type == PSEUDO_VAL)
 545                 return p2->type == PSEUDO_VAL;
 546
 547         if (p1->type == PSEUDO_SYM)
 548                 return p2->type == PSEUDO_SYM || p2->type == PSEUDO_VAL;
 549
 550         return 1;
 551 }
 552
 553 static int simplify_commutative_binop(struct instruction *insn)
 554 {
 555         if (!canonical_order(insn->src1, insn->src2)) {
 556                 switch_pseudo(insn, &insn->src1, insn, &insn->src2);
 557                 return REPEAT_CSE;
 558         }
 559         return 0;
 560 }
 561
 562 static inline int simple_pseudo(pseudo_t pseudo)
 563 {
 564         return pseudo->type == PSEUDO_VAL || pseudo->type == PSEUDO_SYM;
 565 }
 566
 567 static int simplify_associative_binop(struct instruction *insn)
 568 {
 569         struct instruction *def;
 570         pseudo_t pseudo = insn->src1;
 571
 572         if (!simple_pseudo(insn->src2))
 573                 return 0;
 574         if (pseudo->type != PSEUDO_REG)
 575                 return 0;
 576         def = pseudo->def;
 577         if (def == insn)
 578                 return 0;
 579         if (def->opcode != insn->opcode)
 580                 return 0;
 581         if (!simple_pseudo(def->src2))
 582                 return 0;
 583         if (ptr_list_size((struct ptr_list *)def->target->users) != 1)
 584                 return 0;
 585         switch_pseudo(def, &def->src1, insn, &insn->src2);
 586         return REPEAT_CSE;
 587 }
 588
 589 static int simplify_constant_unop(struct instruction *insn)
 590 {
 591         long long val = insn->src1->value;
 592         long long res, mask;
 593
 594         switch (insn->opcode) {
 595         case OP_NOT:
 596                 res = ~val;
 597                 break;
 598         case OP_NEG:
 599                 res = -val;
 600                 break;
 601         default:
 602                 return 0;
 603         }
 604         mask = 1ULL << (insn->size-1);
 605         res &= mask | (mask-1);
 606
 607         replace_with_pseudo(insn, value_pseudo(res));
 608         return REPEAT_CSE;
 609 }
 610
 611 static int simplify_unop(struct instruction *insn)
 612 {
 613         if (dead_insn(insn, &insn->src1, NULL, NULL))
 614                 return REPEAT_CSE;
 615         if (constant(insn->src1))
 616                 return simplify_constant_unop(insn);
 617         return 0;
 618 }
 619
 620 static int simplify_one_memop(struct instruction *insn, pseudo_t orig)
 621 {
 622         pseudo_t addr = insn->src;
 623         pseudo_t new, off;
 624
 625         if (addr->type == PSEUDO_REG) {
 626                 struct instruction *def = addr->def;
 627                 if (def->opcode == OP_SYMADDR && def->src) {
 628                         kill_use(&insn->src);
 629                         use_pseudo(insn, def->src, &insn->src);
 630                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 631                 }
 632                 if (def->opcode == OP_ADD) {
 633                         new = def->src1;
 634                         off = def->src2;
 635                         if (constant(off))
 636                                 goto offset;
 637                         new = off;
 638                         off = def->src1;
 639                         if (constant(off))
 640                                 goto offset;
 641                         return 0;
 642                 }
 643         }
 644         return 0;
 645
 646 offset:
 647         /* Invalid code */
 648         if (new == orig) {
 649                 if (new == VOID)
 650                         return 0;
 651                 new = VOID;
 652                 warning(insn->pos, "crazy programmer");
 653         }
 654         insn->offset += off->value;
 655         use_pseudo(insn, new, &insn->src);
 656         remove_usage(addr, &insn->src);
 657         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 658 }
 659
 660 /*
 661  * We walk the whole chain of adds/subs backwards. That's not
 662  * only more efficient, but it allows us to find loops.
 663  */
 664 static int simplify_memop(struct instruction *insn)
 665 {
 666         int one, ret = 0;
 667         pseudo_t orig = insn->src;
 668
 669         do {
 670                 one = simplify_one_memop(insn, orig);
 671                 ret |= one;
 672         } while (one);
 673         return ret;
 674 }
 675
 676 static long long get_cast_value(long long val, int old_size, int new_size, int sign)
 677 {
 678         long long mask;
 679
 680         if (sign && new_size > old_size) {
 681                 mask = 1 << (old_size-1);
 682                 if (val & mask)
 683                         val |= ~(mask | (mask-1));
 684         }
 685         mask = 1 << (new_size-1);
 686         return val & (mask | (mask-1));
 687 }
 688
 689 static int simplify_cast(struct instruction *insn)
 690 {
 691         struct symbol *orig_type;
 692         int orig_size, size;
 693         pseudo_t src;
 694
 695         if (dead_insn(insn, &insn->src, NULL, NULL))
 696                 return REPEAT_CSE;
 697
 698         orig_type = insn->orig_type;
 699         if (!orig_type)
 700                 return 0;
 701
 702         /* Keep casts with pointer on either side (not only case of OP_PTRCAST) */
 703         if (is_ptr_type(orig_type) || is_ptr_type(insn->type))
 704                 return 0;
 705
 706         orig_size = orig_type->bit_size;
 707         size = insn->size;
 708         src = insn->src;
 709
 710         /* A cast of a constant? */
 711         if (constant(src)) {
 712                 int sign = orig_type->ctype.modifiers & MOD_SIGNED;
 713                 long long val = get_cast_value(src->value, orig_size, size, sign);
 714                 src = value_pseudo(val);
 715                 goto simplify;
 716         }
 717
 718         /* A cast of a "and" might be a no-op.. */
 719         if (src->type == PSEUDO_REG) {
 720                 struct instruction *def = src->def;
 721                 if (def->opcode == OP_AND && def->size >= size) {
 722                         pseudo_t val = def->src2;
 723                         if (val->type == PSEUDO_VAL) {
 724                                 unsigned long long value = val->value;
 725                                 if (!(value >> (size-1)))
 726                                         goto simplify;
 727                         }
 728                 }
 729         }
 730
 731         if (size == orig_size) {
 732                 int op = (orig_type->ctype.modifiers & MOD_SIGNED) ? OP_SCAST : OP_CAST;
 733                 if (insn->opcode == op)
 734                         goto simplify;
 735         }
 736
 737         return 0;
 738
 739 simplify:
 740         return replace_with_pseudo(insn, src);
 741 }
 742
 743 static int simplify_select(struct instruction *insn)
 744 {
 745         pseudo_t cond, src1, src2;
 746
 747         if (dead_insn(insn, &insn->src1, &insn->src2, &insn->src3))
 748                 return REPEAT_CSE;
 749
 750         cond = insn->src1;
 751         src1 = insn->src2;
 752         src2 = insn->src3;
 753         if (constant(cond) || src1 == src2) {
 754                 pseudo_t *kill, take;
 755                 kill_use(&insn->src1);
 756                 take = cond->value ? src1 : src2;
 757                 kill = cond->value ? &insn->src3 : &insn->src2;
 758                 kill_use(kill);
 759                 replace_with_pseudo(insn, take);
 760                 return REPEAT_CSE;
 761         }
 762         if (constant(src1) && constant(src2)) {
 763                 long long val1 = src1->value;
 764                 long long val2 = src2->value;
 765
 766                 /* The pair 0/1 is special - replace with SETNE/SETEQ */
 767                 if ((val1 | val2) == 1) {
 768                         int opcode = OP_SET_EQ;
 769                         if (val1) {
 770                                 src1 = src2;
 771                                 opcode = OP_SET_NE;
 772                         }
 773                         insn->opcode = opcode;
 774                         /* insn->src1 is already cond */
 775                         insn->src2 = src1; /* Zero */
 776                         return REPEAT_CSE;
 777                 }
 778         }
 779         return 0;
 780 }
 781
 782 static int is_in_range(pseudo_t src, long long low, long long high)
 783 {
 784         long long value;
 785
 786         switch (src->type) {
 787         case PSEUDO_VAL:
 788                 value = src->value;
 789                 return value >= low && value <= high;
 790         default:
 791                 return 0;
 792         }
 793 }
 794
 795 static int simplify_range(struct instruction *insn)
 796 {
 797         pseudo_t src1, src2, src3;
 798
 799         src1 = insn->src1;
 800         src2 = insn->src2;
 801         src3 = insn->src3;
 802         if (src2->type != PSEUDO_VAL || src3->type != PSEUDO_VAL)
 803                 return 0;
 804         if (is_in_range(src1, src2->value, src3->value)) {
 805                 kill_instruction(insn);
 806                 return REPEAT_CSE;
 807         }
 808         return 0;
 809 }
 810
 811 /*
 812  * Simplify "set_ne/eq $0 + br"
 813  */
 814 static int simplify_cond_branch(struct instruction *br, pseudo_t cond, struct instruction *def, pseudo_t *pp)
 815 {
 816         use_pseudo(br, *pp, &br->cond);
 817         remove_usage(cond, &br->cond);
 818         if (def->opcode == OP_SET_EQ) {
 819                 struct basic_block *true = br->bb_true;
 820                 struct basic_block *false = br->bb_false;
 821                 br->bb_false = true;
 822                 br->bb_true = false;
 823         }
 824         return REPEAT_CSE;
 825 }
 826
 827 static int simplify_branch(struct instruction *insn)
 828 {
 829         pseudo_t cond = insn->cond;
 830
 831         if (!cond)
 832                 return 0;
 833
 834         /* Constant conditional */
 835         if (constant(cond)) {
 836                 insert_branch(insn->bb, insn, cond->value ? insn->bb_true : insn->bb_false);
 837                 return REPEAT_CSE;
 838         }
 839
 840         /* Same target? */
 841         if (insn->bb_true == insn->bb_false) {
 842                 struct basic_block *bb = insn->bb;
 843                 struct basic_block *target = insn->bb_false;
 844                 remove_bb_from_list(&target->parents, bb, 1);
 845                 remove_bb_from_list(&bb->children, target, 1);
 846                 insn->bb_false = NULL;
 847                 kill_use(&insn->cond);
 848                 insn->cond = NULL;
 849                 return REPEAT_CSE;
 850         }
 851
 852         /* Conditional on a SETNE $0 or SETEQ $0 */
 853         if (cond->type == PSEUDO_REG) {
 854                 struct instruction *def = cond->def;
 855
 856                 if (def->opcode == OP_SET_NE || def->opcode == OP_SET_EQ) {
 857                         if (constant(def->src1) && !def->src1->value)
 858                                 return simplify_cond_branch(insn, cond, def, &def->src2);
 859                         if (constant(def->src2) && !def->src2->value)
 860                                 return simplify_cond_branch(insn, cond, def, &def->src1);
 861                 }
 862                 if (def->opcode == OP_SEL) {
 863                         if (constant(def->src2) && constant(def->src3)) {
 864                                 long long val1 = def->src2->value;
 865                                 long long val2 = def->src3->value;
 866                                 if (!val1 && !val2) {
 867                                         insert_branch(insn->bb, insn, insn->bb_false);
 868                                         return REPEAT_CSE;
 869                                 }
 870                                 if (val1 && val2) {
 871                                         insert_branch(insn->bb, insn, insn->bb_true);
 872                                         return REPEAT_CSE;
 873                                 }
 874                                 if (val2) {
 875                                         struct basic_block *true = insn->bb_true;
 876                                         struct basic_block *false = insn->bb_false;
 877                                         insn->bb_false = true;
 878                                         insn->bb_true = false;
 879                                 }
 880                                 use_pseudo(insn, def->src1, &insn->cond);
 881                                 remove_usage(cond, &insn->cond);
 882                                 return REPEAT_CSE;
 883                         }
 884                 }
 885                 if (def->opcode == OP_CAST || def->opcode == OP_SCAST) {
 886                         int orig_size = def->orig_type ? def->orig_type->bit_size : 0;
 887                         if (def->size > orig_size) {
 888                                 use_pseudo(insn, def->src, &insn->cond);
 889                                 remove_usage(cond, &insn->cond);
 890                                 return REPEAT_CSE;
 891                         }
 892                 }
 893         }
 894         return 0;
 895 }
 896
 897 static int simplify_switch(struct instruction *insn)
 898 {
 899         pseudo_t cond = insn->cond;
 900         long long val;
 901         struct multijmp *jmp;
 902
 903         if (!constant(cond))
 904                 return 0;
 905         val = insn->cond->value;
 906
 907         FOR_EACH_PTR(insn->multijmp_list, jmp) {
 908                 /* Default case */
 909                 if (jmp->begin > jmp->end)
 910                         goto found;
 911                 if (val >= jmp->begin && val <= jmp->end)
 912                         goto found;
 913         } END_FOR_EACH_PTR(jmp);
 914         warning(insn->pos, "Impossible case statement");
 915         return 0;
 916
 917 found:
 918         insert_branch(insn->bb, insn, jmp->target);
 919         return REPEAT_CSE;
 920 }
 921
 922 int simplify_instruction(struct instruction *insn)
 923 {
 924         if (!insn->bb)
 925                 return 0;
 926         switch (insn->opcode) {
 927         case OP_ADD: case OP_MULS:
 928         case OP_AND: case OP_OR: case OP_XOR:
 929         case OP_AND_BOOL: case OP_OR_BOOL:
 930                 if (simplify_binop(insn))
 931                         return REPEAT_CSE;
 932                 if (simplify_commutative_binop(insn))
 933                         return REPEAT_CSE;
 934                 return simplify_associative_binop(insn);
 935
 936         case OP_MULU:
 937         case OP_SET_EQ: case OP_SET_NE:
 938                 if (simplify_binop(insn))
 939                         return REPEAT_CSE;
 940                 return simplify_commutative_binop(insn);
 941
 942         case OP_SUB:
 943         case OP_DIVU: case OP_DIVS:
 944         case OP_MODU: case OP_MODS:
 945         case OP_SHL:
 946         case OP_LSR: case OP_ASR:
 947         case OP_SET_LE: case OP_SET_GE:
 948         case OP_SET_LT: case OP_SET_GT:
 949         case OP_SET_B:  case OP_SET_A:
 950         case OP_SET_BE: case OP_SET_AE:
 951                 return simplify_binop(insn);
 952
 953         case OP_NOT: case OP_NEG:
 954                 return simplify_unop(insn);
 955         case OP_LOAD: case OP_STORE:
 956                 return simplify_memop(insn);
 957         case OP_SYMADDR:
 958                 if (dead_insn(insn, NULL, NULL, NULL))
 959                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 960                 return replace_with_pseudo(insn, insn->symbol);
 961         case OP_CAST:
 962         case OP_SCAST:
 963         case OP_FPCAST:
 964         case OP_PTRCAST:
 965                 return simplify_cast(insn);
 966         case OP_PHI:
 967                 if (dead_insn(insn, NULL, NULL, NULL)) {
 968                         clear_phi(insn);
 969                         return REPEAT_CSE;
 970                 }
 971                 return clean_up_phi(insn);
 972         case OP_PHISOURCE:
 973                 if (dead_insn(insn, &insn->phi_src, NULL, NULL))
 974                         return REPEAT_CSE;
 975                 break;
 976         case OP_SEL:
 977                 return simplify_select(insn);
 978         case OP_BR:
 979                 return simplify_branch(insn);
 980         case OP_SWITCH:
 981                 return simplify_switch(insn);
 982         case OP_RANGE:
 983                 return simplify_range(insn);
 984         }
 985         return 0;
 986 }