simplify.c

   1 /*
   2  * Simplify - do instruction simplification before CSE
   3  *
   4  * Copyright (C) 2004 Linus Torvalds
   5  */
   6
   7 #include <assert.h>
   8
   9 #include "parse.h"
  10 #include "expression.h"
  11 #include "linearize.h"
  12 #include "flow.h"
  13 #include "symbol.h"
  14
  15 /* Find the trivial parent for a phi-source */
  16 static struct basic_block *phi_parent(struct basic_block *source, pseudo_t pseudo)
  17 {
  18         /* Can't go upwards if the pseudo is defined in the bb it came from.. */
  19         if (pseudo->type == PSEUDO_REG) {
  20                 struct instruction *def = pseudo->def;
  21                 if (def->bb == source)
  22                         return source;
  23         }
  24         if (bb_list_size(source->children) != 1 || bb_list_size(source->parents) != 1)
  25                 return source;
  26         return first_basic_block(source->parents);
  27 }
  28
  29 static void clear_phi(struct instruction *insn)
  30 {
  31         pseudo_t phi;
  32
  33         insn->bb = NULL;
  34         FOR_EACH_PTR(insn->phi_list, phi) {
  35                 *THIS_ADDRESS(phi) = VOID;
  36         } END_FOR_EACH_PTR(phi);
  37 }
  38
  39 static int if_convert_phi(struct instruction *insn)
  40 {
  41         pseudo_t array[3];
  42         struct basic_block *parents[3];
  43         struct basic_block *bb, *bb1, *bb2, *source;
  44         struct instruction *br;
  45         pseudo_t p1, p2;
  46
  47         bb = insn->bb;
  48         if (linearize_ptr_list((struct ptr_list *)insn->phi_list, (void **)array, 3) != 2)
  49                 return 0;
  50         if (linearize_ptr_list((struct ptr_list *)bb->parents, (void **)parents, 3) != 2)
  51                 return 0;
  52         p1 = array[0]->def->src1;
  53         bb1 = array[0]->def->bb;
  54         p2 = array[1]->def->src1;
  55         bb2 = array[1]->def->bb;
  56
  57         /* Only try the simple "direct parents" case */
  58         if ((bb1 != parents[0] || bb2 != parents[1]) &&
  59             (bb1 != parents[1] || bb2 != parents[0]))
  60                 return 0;
  61
  62         /*
  63          * See if we can find a common source for this..
  64          */
  65         source = phi_parent(bb1, p1);
  66         if (source != phi_parent(bb2, p2))
  67                 return 0;
  68
  69         /*
  70          * Cool. We now know that 'source' is the exclusive
  71          * parent of both phi-nodes, so the exit at the
  72          * end of it fully determines which one it is, and
  73          * we can turn it into a select.
  74          *
  75          * HOWEVER, right now we only handle regular
  76          * conditional branches. No multijumps or computed
  77          * stuff. Verify that here.
  78          */
  79         br = last_instruction(source->insns);
  80         if (!br || br->opcode != OP_BR)
  81                 return 0;
  82
  83         assert(br->cond);
  84         assert(br->bb_false);
  85
  86         /*
  87          * We're in business. Match up true/false with p1/p2.
  88          */
  89         if (br->bb_true == bb2 || br->bb_false == bb1) {
  90                 pseudo_t p = p1;
  91                 p1 = p2;
  92                 p2 = p;
  93         }
  94
  95         /*
  96          * OK, we can now replace that last
  97          *
  98          *      br cond, a, b
  99          *
 100          * with the sequence
 101          *
 102          *      setcc cond
 103          *      select pseudo, p1, p2
 104          *      br cond, a, b
 105          *
 106          * and remove the phi-node. If it then
 107          * turns out that 'a' or 'b' is entirely
 108          * empty (common case), and now no longer
 109          * a phi-source, we'll be able to simplify
 110          * the conditional branch too.
 111          */
 112         insert_select(source, br, insn, p1, p2);
 113         clear_phi(insn);
 114         return REPEAT_CSE;
 115 }
 116
 117 static int clean_up_phi(struct instruction *insn)
 118 {
 119         pseudo_t phi;
 120         struct instruction *last;
 121         int same;
 122
 123         last = NULL;
 124         same = 1;
 125         FOR_EACH_PTR(insn->phi_list, phi) {
 126                 struct instruction *def;
 127                 if (phi == VOID)
 128                         continue;
 129                 def = phi->def;
 130                 if (def->src1 == VOID || !def->bb)
 131                         continue;
 132                 if (last) {
 133                         if (last->src1 != def->src1)
 134                                 same = 0;
 135                         continue;
 136                 }
 137                 last = def;
 138         } END_FOR_EACH_PTR(phi);
 139
 140         if (same) {
 141                 pseudo_t pseudo = last ? last->src1 : VOID;
 142                 convert_instruction_target(insn, pseudo);
 143                 clear_phi(insn);
 144                 return REPEAT_CSE;
 145         }
 146
 147         return if_convert_phi(insn);
 148 }
 149
 150 static int delete_pseudo_user_list_entry(struct pseudo_user_list **list, pseudo_t *entry, int count)
 151 {
 152         struct pseudo_user *pu;
 153
 154         FOR_EACH_PTR(*list, pu) {
 155                 if (pu->userp == entry) {
 156                         DELETE_CURRENT_PTR(pu);
 157                         if (!--count)
 158                                 goto out;
 159                 }
 160         } END_FOR_EACH_PTR(pu);
 161         assert(count <= 0);
 162 out:
 163         pack_ptr_list((struct ptr_list **)list);
 164         return count;
 165 }
 166
 167 static inline void remove_usage(pseudo_t p, pseudo_t *usep)
 168 {
 169         if (has_use_list(p)) {
 170                 delete_pseudo_user_list_entry(&p->users, usep, 1);
 171                 if (!p->users)
 172                         kill_instruction(p->def);
 173         }
 174 }
 175
 176 void kill_use(pseudo_t *usep)
 177 {
 178         if (usep) {
 179                 pseudo_t p = *usep;
 180                 *usep = VOID;
 181                 remove_usage(p, usep);
 182         }
 183 }
 184
 185 void kill_instruction(struct instruction *insn)
 186 {
 187         if (!insn || !insn->bb)
 188                 return;
 189
 190         switch (insn->opcode) {
 191         case OP_SEL:
 192         case OP_RANGE:
 193                 kill_use(&insn->src3);
 194                 /* fall through */
 195
 196         case OP_BINARY ... OP_BINCMP_END:
 197                 kill_use(&insn->src2);
 198                 /* fall through */
 199
 200         case OP_CAST:
 201         case OP_SCAST:
 202         case OP_FPCAST:
 203         case OP_PTRCAST:
 204         case OP_SETVAL:
 205         case OP_NOT: case OP_NEG:
 206                 kill_use(&insn->src1);
 207                 break;
 208
 209         case OP_PHI:
 210                 clear_phi(insn);
 211                 break;
 212
 213         case OP_SYMADDR:
 214                 repeat_phase |= REPEAT_SYMBOL_CLEANUP;
 215                 break;
 216
 217         case OP_BR:
 218                 if (!insn->bb_true || !insn->bb_false)
 219                         break;
 220                 /* fall through */
 221
 222         case OP_COMPUTEDGOTO:
 223                 kill_use(&insn->cond);
 224                 break;
 225
 226         case OP_ENTRY:
 227         default:
 228                 /* ignore */
 229                 return;
 230         }
 231
 232         insn->bb = NULL;
 233         repeat_phase |= REPEAT_CSE;
 234         return;
 235 }
 236
 237 /*
 238  * Kill trivially dead instructions
 239  */
 240 static int dead_insn(struct instruction *insn, pseudo_t *src1, pseudo_t *src2, pseudo_t *src3)
 241 {
 242         struct pseudo_user *pu;
 243         FOR_EACH_PTR(insn->target->users, pu) {
 244                 if (*pu->userp != VOID)
 245                         return 0;
 246         } END_FOR_EACH_PTR(pu);
 247
 248         insn->bb = NULL;
 249         kill_use(src1);
 250         kill_use(src2);
 251         kill_use(src3);
 252         return REPEAT_CSE;
 253 }
 254
 255 static inline int constant(pseudo_t pseudo)
 256 {
 257         return pseudo->type == PSEUDO_VAL;
 258 }
 259
 260 static int replace_with_pseudo(struct instruction *insn, pseudo_t pseudo)
 261 {
 262         convert_instruction_target(insn, pseudo);
 263
 264         switch (insn->opcode) {
 265         case OP_SEL:
 266         case OP_RANGE:
 267                 kill_use(&insn->src3);
 268         case OP_BINARY ... OP_BINCMP_END:
 269                 kill_use(&insn->src2);
 270         case OP_NOT:
 271         case OP_NEG:
 272         case OP_SYMADDR:
 273         case OP_CAST:
 274         case OP_SCAST:
 275         case OP_FPCAST:
 276         case OP_PTRCAST:
 277                 kill_use(&insn->src1);
 278                 break;
 279
 280         default:
 281                 assert(0);
 282         }
 283         insn->bb = NULL;
 284         return REPEAT_CSE;
 285 }
 286
 287 static unsigned int value_size(long long value)
 288 {
 289         value >>= 8;
 290         if (!value)
 291                 return 8;
 292         value >>= 8;
 293         if (!value)
 294                 return 16;
 295         value >>= 16;
 296         if (!value)
 297                 return 32;
 298         return 64;
 299 }
 300
 301 /*
 302  * Try to determine the maximum size of bits in a pseudo.
 303  *
 304  * Right now this only follow casts and constant values, but we
 305  * could look at things like logical 'and' instructions etc.
 306  */
 307 static unsigned int operand_size(struct instruction *insn, pseudo_t pseudo)
 308 {
 309         unsigned int size = insn->size;
 310
 311         if (pseudo->type == PSEUDO_REG) {
 312                 struct instruction *src = pseudo->def;
 313                 if (src && src->opcode == OP_CAST && src->orig_type) {
 314                         unsigned int orig_size = src->orig_type->bit_size;
 315                         if (orig_size < size)
 316                                 size = orig_size;
 317                 }
 318         }
 319         if (pseudo->type == PSEUDO_VAL) {
 320                 unsigned int orig_size = value_size(pseudo->value);
 321                 if (orig_size < size)
 322                         size = orig_size;
 323         }
 324         return size;
 325 }
 326
 327 static int simplify_asr(struct instruction *insn, pseudo_t pseudo, long long value)
 328 {
 329         unsigned int size = operand_size(insn, pseudo);
 330
 331         if (value >= size) {
 332                 warning(insn->pos, "right shift by bigger than source value");
 333                 return replace_with_pseudo(insn, value_pseudo(0));
 334         }
 335         if (!value)
 336                 return replace_with_pseudo(insn, pseudo);
 337         return 0;
 338 }
 339
 340 static int simplify_mul_div(struct instruction *insn, long long value)
 341 {
 342         unsigned long long sbit = 1ULL << (insn->size - 1);
 343         unsigned long long bits = sbit | (sbit - 1);
 344
 345         if (value == 1)
 346                 return replace_with_pseudo(insn, insn->src1);
 347
 348         switch (insn->opcode) {
 349         case OP_MULS:
 350         case OP_MULU:
 351                 if (value == 0)
 352                         return replace_with_pseudo(insn, insn->src2);
 353         /* Fall through */
 354         case OP_DIVS:
 355                 if (!(value & sbit))    // positive
 356                         break;
 357
 358                 value |= ~bits;
 359                 if (value == -1) {
 360                         insn->opcode = OP_NEG;
 361                         return REPEAT_CSE;
 362                 }
 363         }
 364
 365         return 0;
 366 }
 367
 368 static int simplify_constant_rightside(struct instruction *insn)
 369 {
 370         long long value = insn->src2->value;
 371
 372         switch (insn->opcode) {
 373         case OP_OR_BOOL:
 374                 if (value == 1)
 375                         return replace_with_pseudo(insn, insn->src2);
 376                 goto case_neutral_zero;
 377
 378         case OP_SUB:
 379                 if (value) {
 380                         insn->opcode = OP_ADD;
 381                         insn->src2 = value_pseudo(-value);
 382                         return REPEAT_CSE;
 383                 }
 384         /* Fall through */
 385         case OP_ADD:
 386         case OP_OR: case OP_XOR:
 387         case OP_SHL:
 388         case OP_LSR:
 389         case_neutral_zero:
 390                 if (!value)
 391                         return replace_with_pseudo(insn, insn->src1);
 392                 return 0;
 393         case OP_ASR:
 394                 return simplify_asr(insn, insn->src1, value);
 395
 396         case OP_MODU: case OP_MODS:
 397                 if (value == 1)
 398                         return replace_with_pseudo(insn, value_pseudo(0));
 399                 return 0;
 400
 401         case OP_DIVU: case OP_DIVS:
 402         case OP_MULU: case OP_MULS:
 403                 return simplify_mul_div(insn, value);
 404
 405         case OP_AND_BOOL:
 406                 if (value == 1)
 407                         return replace_with_pseudo(insn, insn->src1);
 408         /* Fall through */
 409         case OP_AND:
 410                 if (!value)
 411                         return replace_with_pseudo(insn, insn->src2);
 412                 return 0;
 413         }
 414         return 0;
 415 }
 416
 417 static int simplify_constant_leftside(struct instruction *insn)
 418 {
 419         long long value = insn->src1->value;
 420
 421         switch (insn->opcode) {
 422         case OP_ADD: case OP_OR: case OP_XOR:
 423                 if (!value)
 424                         return replace_with_pseudo(insn, insn->src2);
 425                 return 0;
 426
 427         case OP_SHL:
 428         case OP_LSR: case OP_ASR:
 429         case OP_AND:
 430         case OP_MULU: case OP_MULS:
 431                 if (!value)
 432                         return replace_with_pseudo(insn, insn->src1);
 433                 return 0;
 434         }
 435         return 0;
 436 }
 437
 438 static int simplify_constant_binop(struct instruction *insn)
 439 {
 440         /* FIXME! Verify signs and sizes!! */
 441         long long left = insn->src1->value;
 442         long long right = insn->src2->value;
 443         unsigned long long ul, ur;
 444         long long res, mask, bits;
 445
 446         mask = 1ULL << (insn->size-1);
 447         bits = mask | (mask-1);
 448
 449         if (left & mask)
 450                 left |= ~bits;
 451         if (right & mask)
 452                 right |= ~bits;
 453         ul = left & bits;
 454         ur = right & bits;
 455
 456         switch (insn->opcode) {
 457         case OP_ADD:
 458                 res = left + right;
 459                 break;
 460         case OP_SUB:
 461                 res = left - right;
 462                 break;
 463         case OP_MULU:
 464                 res = ul * ur;
 465                 break;
 466         case OP_MULS:
 467                 res = left * right;
 468                 break;
 469         case OP_DIVU:
 470                 if (!ur)
 471                         return 0;
 472                 res = ul / ur;
 473                 break;
 474         case OP_DIVS:
 475                 if (!right)
 476                         return 0;
 477                 if (left == mask && right == -1)
 478                         return 0;
 479                 res = left / right;
 480                 break;
 481         case OP_MODU:
 482                 if (!ur)
 483                         return 0;
 484                 res = ul % ur;
 485                 break;
 486         case OP_MODS:
 487                 if (!right)
 488                         return 0;
 489                 if (left == mask && right == -1)
 490                         return 0;
 491                 res = left % right;
 492                 break;
 493         case OP_SHL:
 494                 res = left << right;
 495                 break;
 496         case OP_LSR:
 497                 res = ul >> ur;
 498                 break;
 499         case OP_ASR:
 500                 res = left >> right;
 501                 break;
 502        /* Logical */
 503         case OP_AND:
 504                 res = left & right;
 505                 break;
 506         case OP_OR:
 507                 res = left | right;
 508                 break;
 509         case OP_XOR:
 510                 res = left ^ right;
 511                 break;
 512         case OP_AND_BOOL:
 513                 res = left && right;
 514                 break;
 515         case OP_OR_BOOL:
 516                 res = left || right;
 517                 break;
 518
 519         /* Binary comparison */
 520         case OP_SET_EQ:
 521                 res = left == right;
 522                 break;
 523         case OP_SET_NE:
 524                 res = left != right;
 525                 break;
 526         case OP_SET_LE:
 527                 res = left <= right;
 528                 break;
 529         case OP_SET_GE:
 530                 res = left >= right;
 531                 break;
 532         case OP_SET_LT:
 533                 res = left < right;
 534                 break;
 535         case OP_SET_GT:
 536                 res = left > right;
 537                 break;
 538         case OP_SET_B:
 539                 res = ul < ur;
 540                 break;
 541         case OP_SET_A:
 542                 res = ul > ur;
 543                 break;
 544         case OP_SET_BE:
 545                 res = ul <= ur;
 546                 break;
 547         case OP_SET_AE:
 548                 res = ul >= ur;
 549                 break;
 550         default:
 551                 return 0;
 552         }
 553         res &= bits;
 554
 555         replace_with_pseudo(insn, value_pseudo(res));
 556         return REPEAT_CSE;
 557 }
 558
 559 static int simplify_binop_same_args(struct instruction *insn, pseudo_t arg)
 560 {
 561         switch (insn->opcode) {
 562         case OP_SET_NE:
 563         case OP_SET_LT: case OP_SET_GT:
 564         case OP_SET_B:  case OP_SET_A:
 565         case OP_SUB:
 566         case OP_XOR:
 567                 return replace_with_pseudo(insn, value_pseudo(0));
 568
 569         case OP_SET_EQ:
 570         case OP_SET_LE: case OP_SET_GE:
 571         case OP_SET_BE: case OP_SET_AE:
 572                 return replace_with_pseudo(insn, value_pseudo(1));
 573
 574         case OP_AND:
 575         case OP_OR:
 576                 return replace_with_pseudo(insn, arg);
 577
 578         case OP_AND_BOOL:
 579         case OP_OR_BOOL:
 580                 // simplification is correct only if the operands
 581                 // have already been compared against zero which
 582                 // is not enforced.
 583                 break;
 584
 585         default:
 586                 break;
 587         }
 588
 589         return 0;
 590 }
 591
 592 static int simplify_binop(struct instruction *insn)
 593 {
 594         if (dead_insn(insn, &insn->src1, &insn->src2, NULL))
 595                 return REPEAT_CSE;
 596         if (constant(insn->src1)) {
 597                 if (constant(insn->src2))
 598                         return simplify_constant_binop(insn);
 599                 return simplify_constant_leftside(insn);
 600         }
 601         if (constant(insn->src2))
 602                 return simplify_constant_rightside(insn);
 603         if (insn->src1 == insn->src2)
 604                 return simplify_binop_same_args(insn, insn->src1);
 605         return 0;
 606 }
 607
 608 static void switch_pseudo(struct instruction *insn1, pseudo_t *pp1, struct instruction *insn2, pseudo_t *pp2)
 609 {
 610         pseudo_t p1 = *pp1, p2 = *pp2;
 611
 612         use_pseudo(insn1, p2, pp1);
 613         use_pseudo(insn2, p1, pp2);
 614         remove_usage(p1, pp1);
 615         remove_usage(p2, pp2);
 616 }
 617
 618 static int canonical_order(pseudo_t p1, pseudo_t p2)
 619 {
 620         /* symbol/constants on the right */
 621         if (p1->type == PSEUDO_VAL)
 622                 return p2->type == PSEUDO_VAL;
 623
 624         if (p1->type == PSEUDO_SYM)
 625                 return p2->type == PSEUDO_SYM || p2->type == PSEUDO_VAL;
 626
 627         return 1;
 628 }
 629
 630 static int simplify_commutative_binop(struct instruction *insn)
 631 {
 632         if (!canonical_order(insn->src1, insn->src2)) {
 633                 switch_pseudo(insn, &insn->src1, insn, &insn->src2);
 634                 return REPEAT_CSE;
 635         }
 636         return 0;
 637 }
 638
 639 static inline int simple_pseudo(pseudo_t pseudo)
 640 {
 641         return pseudo->type == PSEUDO_VAL || pseudo->type == PSEUDO_SYM;
 642 }
 643
 644 static int simplify_associative_binop(struct instruction *insn)
 645 {
 646         struct instruction *def;
 647         pseudo_t pseudo = insn->src1;
 648
 649         if (!simple_pseudo(insn->src2))
 650                 return 0;
 651         if (pseudo->type != PSEUDO_REG)
 652                 return 0;
 653         def = pseudo->def;
 654         if (def == insn)
 655                 return 0;
 656         if (def->opcode != insn->opcode)
 657                 return 0;
 658         if (!simple_pseudo(def->src2))
 659                 return 0;
 660         if (ptr_list_size((struct ptr_list *)def->target->users) != 1)
 661                 return 0;
 662         switch_pseudo(def, &def->src1, insn, &insn->src2);
 663         return REPEAT_CSE;
 664 }
 665
 666 static int simplify_constant_unop(struct instruction *insn)
 667 {
 668         long long val = insn->src1->value;
 669         long long res, mask;
 670
 671         switch (insn->opcode) {
 672         case OP_NOT:
 673                 res = ~val;
 674                 break;
 675         case OP_NEG:
 676                 res = -val;
 677                 break;
 678         default:
 679                 return 0;
 680         }
 681         mask = 1ULL << (insn->size-1);
 682         res &= mask | (mask-1);
 683
 684         replace_with_pseudo(insn, value_pseudo(res));
 685         return REPEAT_CSE;
 686 }
 687
 688 static int simplify_unop(struct instruction *insn)
 689 {
 690         if (dead_insn(insn, &insn->src1, NULL, NULL))
 691                 return REPEAT_CSE;
 692         if (constant(insn->src1))
 693                 return simplify_constant_unop(insn);
 694
 695         switch (insn->opcode) {
 696                 struct instruction *def;
 697
 698         case OP_NOT:
 699                 def = insn->src->def;
 700                 if (def && def->opcode == OP_NOT)
 701                         return replace_with_pseudo(insn, def->src);
 702                 break;
 703         case OP_NEG:
 704                 def = insn->src->def;
 705                 if (def && def->opcode == OP_NEG)
 706                         return replace_with_pseudo(insn, def->src);
 707                 break;
 708         default:
 709                 return 0;
 710         }
 711         return 0;
 712 }
 713
 714 static int simplify_one_memop(struct instruction *insn, pseudo_t orig)
 715 {
 716         pseudo_t addr = insn->src;
 717         pseudo_t new, off;
 718
 719         if (addr->type == PSEUDO_REG) {
 720                 struct instruction *def = addr->def;
 721                 if (def->opcode == OP_SYMADDR && def->src) {
 722                         kill_use(&insn->src);
 723                         use_pseudo(insn, def->src, &insn->src);
 724                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 725                 }
 726                 if (def->opcode == OP_ADD) {
 727                         new = def->src1;
 728                         off = def->src2;
 729                         if (constant(off))
 730                                 goto offset;
 731                         new = off;
 732                         off = def->src1;
 733                         if (constant(off))
 734                                 goto offset;
 735                         return 0;
 736                 }
 737         }
 738         return 0;
 739
 740 offset:
 741         /* Invalid code */
 742         if (new == orig) {
 743                 if (new == VOID)
 744                         return 0;
 745                 new = VOID;
 746                 warning(insn->pos, "crazy programmer");
 747         }
 748         insn->offset += off->value;
 749         use_pseudo(insn, new, &insn->src);
 750         remove_usage(addr, &insn->src);
 751         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 752 }
 753
 754 /*
 755  * We walk the whole chain of adds/subs backwards. That's not
 756  * only more efficient, but it allows us to find loops.
 757  */
 758 static int simplify_memop(struct instruction *insn)
 759 {
 760         int one, ret = 0;
 761         pseudo_t orig = insn->src;
 762
 763         do {
 764                 one = simplify_one_memop(insn, orig);
 765                 ret |= one;
 766         } while (one);
 767         return ret;
 768 }
 769
 770 static long long get_cast_value(long long val, int old_size, int new_size, int sign)
 771 {
 772         long long mask;
 773
 774         if (sign && new_size > old_size) {
 775                 mask = 1 << (old_size-1);
 776                 if (val & mask)
 777                         val |= ~(mask | (mask-1));
 778         }
 779         mask = 1 << (new_size-1);
 780         return val & (mask | (mask-1));
 781 }
 782
 783 static int simplify_cast(struct instruction *insn)
 784 {
 785         struct symbol *orig_type;
 786         int orig_size, size;
 787         pseudo_t src;
 788
 789         if (dead_insn(insn, &insn->src, NULL, NULL))
 790                 return REPEAT_CSE;
 791
 792         orig_type = insn->orig_type;
 793         if (!orig_type)
 794                 return 0;
 795
 796         /* Keep casts with pointer on either side (not only case of OP_PTRCAST) */
 797         if (is_ptr_type(orig_type) || is_ptr_type(insn->type))
 798                 return 0;
 799
 800         orig_size = orig_type->bit_size;
 801         size = insn->size;
 802         src = insn->src;
 803
 804         /* A cast of a constant? */
 805         if (constant(src)) {
 806                 int sign = orig_type->ctype.modifiers & MOD_SIGNED;
 807                 long long val = get_cast_value(src->value, orig_size, size, sign);
 808                 src = value_pseudo(val);
 809                 goto simplify;
 810         }
 811
 812         /* A cast of a "and" might be a no-op.. */
 813         if (src->type == PSEUDO_REG) {
 814                 struct instruction *def = src->def;
 815                 if (def->opcode == OP_AND && def->size >= size) {
 816                         pseudo_t val = def->src2;
 817                         if (val->type == PSEUDO_VAL) {
 818                                 unsigned long long value = val->value;
 819                                 if (!(value >> (size-1)))
 820                                         goto simplify;
 821                         }
 822                 }
 823         }
 824
 825         if (size == orig_size) {
 826                 int op = (orig_type->ctype.modifiers & MOD_SIGNED) ? OP_SCAST : OP_CAST;
 827                 if (insn->opcode == op)
 828                         goto simplify;
 829         }
 830
 831         return 0;
 832
 833 simplify:
 834         return replace_with_pseudo(insn, src);
 835 }
 836
 837 static int simplify_select(struct instruction *insn)
 838 {
 839         pseudo_t cond, src1, src2;
 840
 841         if (dead_insn(insn, &insn->src1, &insn->src2, &insn->src3))
 842                 return REPEAT_CSE;
 843
 844         cond = insn->src1;
 845         src1 = insn->src2;
 846         src2 = insn->src3;
 847         if (constant(cond) || src1 == src2) {
 848                 pseudo_t *kill, take;
 849                 kill_use(&insn->src1);
 850                 take = cond->value ? src1 : src2;
 851                 kill = cond->value ? &insn->src3 : &insn->src2;
 852                 kill_use(kill);
 853                 replace_with_pseudo(insn, take);
 854                 return REPEAT_CSE;
 855         }
 856         if (constant(src1) && constant(src2)) {
 857                 long long val1 = src1->value;
 858                 long long val2 = src2->value;
 859
 860                 /* The pair 0/1 is special - replace with SETNE/SETEQ */
 861                 if ((val1 | val2) == 1) {
 862                         int opcode = OP_SET_EQ;
 863                         if (val1) {
 864                                 src1 = src2;
 865                                 opcode = OP_SET_NE;
 866                         }
 867                         insn->opcode = opcode;
 868                         /* insn->src1 is already cond */
 869                         insn->src2 = src1; /* Zero */
 870                         return REPEAT_CSE;
 871                 }
 872         }
 873         return 0;
 874 }
 875
 876 static int is_in_range(pseudo_t src, long long low, long long high)
 877 {
 878         long long value;
 879
 880         switch (src->type) {
 881         case PSEUDO_VAL:
 882                 value = src->value;
 883                 return value >= low && value <= high;
 884         default:
 885                 return 0;
 886         }
 887 }
 888
 889 static int simplify_range(struct instruction *insn)
 890 {
 891         pseudo_t src1, src2, src3;
 892
 893         src1 = insn->src1;
 894         src2 = insn->src2;
 895         src3 = insn->src3;
 896         if (src2->type != PSEUDO_VAL || src3->type != PSEUDO_VAL)
 897                 return 0;
 898         if (is_in_range(src1, src2->value, src3->value)) {
 899                 kill_instruction(insn);
 900                 return REPEAT_CSE;
 901         }
 902         return 0;
 903 }
 904
 905 /*
 906  * Simplify "set_ne/eq $0 + br"
 907  */
 908 static int simplify_cond_branch(struct instruction *br, pseudo_t cond, struct instruction *def, pseudo_t *pp)
 909 {
 910         use_pseudo(br, *pp, &br->cond);
 911         remove_usage(cond, &br->cond);
 912         if (def->opcode == OP_SET_EQ) {
 913                 struct basic_block *true = br->bb_true;
 914                 struct basic_block *false = br->bb_false;
 915                 br->bb_false = true;
 916                 br->bb_true = false;
 917         }
 918         return REPEAT_CSE;
 919 }
 920
 921 static int simplify_branch(struct instruction *insn)
 922 {
 923         pseudo_t cond = insn->cond;
 924
 925         if (!cond)
 926                 return 0;
 927
 928         /* Constant conditional */
 929         if (constant(cond)) {
 930                 insert_branch(insn->bb, insn, cond->value ? insn->bb_true : insn->bb_false);
 931                 return REPEAT_CSE;
 932         }
 933
 934         /* Same target? */
 935         if (insn->bb_true == insn->bb_false) {
 936                 struct basic_block *bb = insn->bb;
 937                 struct basic_block *target = insn->bb_false;
 938                 remove_bb_from_list(&target->parents, bb, 1);
 939                 remove_bb_from_list(&bb->children, target, 1);
 940                 insn->bb_false = NULL;
 941                 kill_use(&insn->cond);
 942                 insn->cond = NULL;
 943                 return REPEAT_CSE;
 944         }
 945
 946         /* Conditional on a SETNE $0 or SETEQ $0 */
 947         if (cond->type == PSEUDO_REG) {
 948                 struct instruction *def = cond->def;
 949
 950                 if (def->opcode == OP_SET_NE || def->opcode == OP_SET_EQ) {
 951                         if (constant(def->src1) && !def->src1->value)
 952                                 return simplify_cond_branch(insn, cond, def, &def->src2);
 953                         if (constant(def->src2) && !def->src2->value)
 954                                 return simplify_cond_branch(insn, cond, def, &def->src1);
 955                 }
 956                 if (def->opcode == OP_SEL) {
 957                         if (constant(def->src2) && constant(def->src3)) {
 958                                 long long val1 = def->src2->value;
 959                                 long long val2 = def->src3->value;
 960                                 if (!val1 && !val2) {
 961                                         insert_branch(insn->bb, insn, insn->bb_false);
 962                                         return REPEAT_CSE;
 963                                 }
 964                                 if (val1 && val2) {
 965                                         insert_branch(insn->bb, insn, insn->bb_true);
 966                                         return REPEAT_CSE;
 967                                 }
 968                                 if (val2) {
 969                                         struct basic_block *true = insn->bb_true;
 970                                         struct basic_block *false = insn->bb_false;
 971                                         insn->bb_false = true;
 972                                         insn->bb_true = false;
 973                                 }
 974                                 use_pseudo(insn, def->src1, &insn->cond);
 975                                 remove_usage(cond, &insn->cond);
 976                                 return REPEAT_CSE;
 977                         }
 978                 }
 979                 if (def->opcode == OP_CAST || def->opcode == OP_SCAST) {
 980                         int orig_size = def->orig_type ? def->orig_type->bit_size : 0;
 981                         if (def->size > orig_size) {
 982                                 use_pseudo(insn, def->src, &insn->cond);
 983                                 remove_usage(cond, &insn->cond);
 984                                 return REPEAT_CSE;
 985                         }
 986                 }
 987         }
 988         return 0;
 989 }
 990
 991 static int simplify_switch(struct instruction *insn)
 992 {
 993         pseudo_t cond = insn->cond;
 994         long long val;
 995         struct multijmp *jmp;
 996
 997         if (!constant(cond))
 998                 return 0;
 999         val = insn->cond->value;
1000
1001         FOR_EACH_PTR(insn->multijmp_list, jmp) {
1002                 /* Default case */
1003                 if (jmp->begin > jmp->end)
1004                         goto found;
1005                 if (val >= jmp->begin && val <= jmp->end)
1006                         goto found;
1007         } END_FOR_EACH_PTR(jmp);
1008         warning(insn->pos, "Impossible case statement");
1009         return 0;
1010
1011 found:
1012         insert_branch(insn->bb, insn, jmp->target);
1013         return REPEAT_CSE;
1014 }
1015
1016 int simplify_instruction(struct instruction *insn)
1017 {
1018         if (!insn->bb)
1019                 return 0;
1020         switch (insn->opcode) {
1021         case OP_ADD: case OP_MULS:
1022         case OP_AND: case OP_OR: case OP_XOR:
1023         case OP_AND_BOOL: case OP_OR_BOOL:
1024                 if (simplify_binop(insn))
1025                         return REPEAT_CSE;
1026                 if (simplify_commutative_binop(insn))
1027                         return REPEAT_CSE;
1028                 return simplify_associative_binop(insn);
1029
1030         case OP_MULU:
1031         case OP_SET_EQ: case OP_SET_NE:
1032                 if (simplify_binop(insn))
1033                         return REPEAT_CSE;
1034                 return simplify_commutative_binop(insn);
1035
1036         case OP_SUB:
1037         case OP_DIVU: case OP_DIVS:
1038         case OP_MODU: case OP_MODS:
1039         case OP_SHL:
1040         case OP_LSR: case OP_ASR:
1041         case OP_SET_LE: case OP_SET_GE:
1042         case OP_SET_LT: case OP_SET_GT:
1043         case OP_SET_B:  case OP_SET_A:
1044         case OP_SET_BE: case OP_SET_AE:
1045                 return simplify_binop(insn);
1046
1047         case OP_NOT: case OP_NEG:
1048                 return simplify_unop(insn);
1049         case OP_LOAD: case OP_STORE:
1050                 return simplify_memop(insn);
1051         case OP_SYMADDR:
1052                 if (dead_insn(insn, NULL, NULL, NULL))
1053                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
1054                 return replace_with_pseudo(insn, insn->symbol);
1055         case OP_CAST:
1056         case OP_SCAST:
1057         case OP_FPCAST:
1058         case OP_PTRCAST:
1059                 return simplify_cast(insn);
1060         case OP_PHI:
1061                 if (dead_insn(insn, NULL, NULL, NULL)) {
1062                         clear_phi(insn);
1063                         return REPEAT_CSE;
1064                 }
1065                 return clean_up_phi(insn);
1066         case OP_PHISOURCE:
1067                 if (dead_insn(insn, &insn->phi_src, NULL, NULL))
1068                         return REPEAT_CSE;
1069                 break;
1070         case OP_SEL:
1071                 return simplify_select(insn);
1072         case OP_BR:
1073                 return simplify_branch(insn);
1074         case OP_SWITCH:
1075                 return simplify_switch(insn);
1076         case OP_RANGE:
1077                 return simplify_range(insn);
1078         }
1079         return 0;
1080 }