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_BINARY ... OP_BINCMP_END:
 192                 insn->bb = NULL;
 193                 kill_use(&insn->src1);
 194                 kill_use(&insn->src2);
 195                 repeat_phase |= REPEAT_CSE;
 196                 return;
 197
 198         case OP_NOT: case OP_NEG:
 199                 insn->bb = NULL;
 200                 kill_use(&insn->src1);
 201                 repeat_phase |= REPEAT_CSE;
 202                 return;
 203
 204         case OP_PHI:
 205                 insn->bb = NULL;
 206                 repeat_phase |= REPEAT_CSE;
 207                 return;
 208
 209         case OP_SYMADDR:
 210                 insn->bb = NULL;
 211                 repeat_phase |= REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 212                 return;
 213
 214         case OP_RANGE:
 215                 insn->bb = NULL;
 216                 repeat_phase |= REPEAT_CSE;
 217                 kill_use(&insn->src1);
 218                 kill_use(&insn->src2);
 219                 kill_use(&insn->src3);
 220                 return;
 221         case OP_BR:
 222                 insn->bb = NULL;
 223                 repeat_phase |= REPEAT_CSE;
 224                 if (insn->cond)
 225                         kill_use(&insn->cond);
 226                 return;
 227         }
 228 }
 229
 230 /*
 231  * Kill trivially dead instructions
 232  */
 233 static int dead_insn(struct instruction *insn, pseudo_t *src1, pseudo_t *src2, pseudo_t *src3)
 234 {
 235         struct pseudo_user *pu;
 236         FOR_EACH_PTR(insn->target->users, pu) {
 237                 if (*pu->userp != VOID)
 238                         return 0;
 239         } END_FOR_EACH_PTR(pu);
 240
 241         insn->bb = NULL;
 242         kill_use(src1);
 243         kill_use(src2);
 244         kill_use(src3);
 245         return REPEAT_CSE;
 246 }
 247
 248 static inline int constant(pseudo_t pseudo)
 249 {
 250         return pseudo->type == PSEUDO_VAL;
 251 }
 252
 253 static int replace_with_pseudo(struct instruction *insn, pseudo_t pseudo)
 254 {
 255         convert_instruction_target(insn, pseudo);
 256         insn->bb = NULL;
 257         return REPEAT_CSE;
 258 }
 259
 260 static unsigned int value_size(long long value)
 261 {
 262         value >>= 8;
 263         if (!value)
 264                 return 8;
 265         value >>= 8;
 266         if (!value)
 267                 return 16;
 268         value >>= 16;
 269         if (!value)
 270                 return 32;
 271         return 64;
 272 }
 273
 274 /*
 275  * Try to determine the maximum size of bits in a pseudo.
 276  *
 277  * Right now this only follow casts and constant values, but we
 278  * could look at things like logical 'and' instructions etc.
 279  */
 280 static unsigned int operand_size(struct instruction *insn, pseudo_t pseudo)
 281 {
 282         unsigned int size = insn->size;
 283
 284         if (pseudo->type == PSEUDO_REG) {
 285                 struct instruction *src = pseudo->def;
 286                 if (src && src->opcode == OP_CAST && src->orig_type) {
 287                         unsigned int orig_size = src->orig_type->bit_size;
 288                         if (orig_size < size)
 289                                 size = orig_size;
 290                 }
 291         }
 292         if (pseudo->type == PSEUDO_VAL) {
 293                 unsigned int orig_size = value_size(pseudo->value);
 294                 if (orig_size < size)
 295                         size = orig_size;
 296         }
 297         return size;
 298 }
 299
 300 static int simplify_asr(struct instruction *insn, pseudo_t pseudo, long long value)
 301 {
 302         unsigned int size = operand_size(insn, pseudo);
 303
 304         if (value >= size) {
 305                 warning(insn->pos, "right shift by bigger than source value");
 306                 return replace_with_pseudo(insn, value_pseudo(0));
 307         }
 308         if (!value)
 309                 return replace_with_pseudo(insn, pseudo);
 310         return 0;
 311 }
 312
 313 static int simplify_constant_rightside(struct instruction *insn)
 314 {
 315         long long value = insn->src2->value;
 316
 317         switch (insn->opcode) {
 318         case OP_SUB:
 319                 if (value) {
 320                         insn->opcode = OP_ADD;
 321                         insn->src2 = value_pseudo(-value);
 322                         return REPEAT_CSE;
 323                 }
 324         /* Fall through */
 325         case OP_ADD:
 326         case OP_OR: case OP_XOR:
 327         case OP_OR_BOOL:
 328         case OP_SHL:
 329         case OP_LSR:
 330                 if (!value)
 331                         return replace_with_pseudo(insn, insn->src1);
 332                 return 0;
 333         case OP_ASR:
 334                 return simplify_asr(insn, insn->src1, value);
 335
 336         case OP_MULU: case OP_MULS:
 337         case OP_AND_BOOL:
 338                 if (value == 1)
 339                         return replace_with_pseudo(insn, insn->src1);
 340         /* Fall through */
 341         case OP_AND:
 342                 if (!value)
 343                         return replace_with_pseudo(insn, insn->src2);
 344                 return 0;
 345         }
 346         return 0;
 347 }
 348
 349 static int simplify_constant_leftside(struct instruction *insn)
 350 {
 351         long long value = insn->src1->value;
 352
 353         switch (insn->opcode) {
 354         case OP_ADD: case OP_OR: case OP_XOR:
 355                 if (!value)
 356                         return replace_with_pseudo(insn, insn->src2);
 357                 return 0;
 358
 359         case OP_SHL:
 360         case OP_LSR: case OP_ASR:
 361         case OP_AND:
 362         case OP_MULU: case OP_MULS:
 363                 if (!value)
 364                         return replace_with_pseudo(insn, insn->src1);
 365                 return 0;
 366         }
 367         return 0;
 368 }
 369
 370 static int simplify_constant_binop(struct instruction *insn)
 371 {
 372         /* FIXME! Verify signs and sizes!! */
 373         long long left = insn->src1->value;
 374         long long right = insn->src2->value;
 375         unsigned long long ul, ur;
 376         long long res, mask, bits;
 377
 378         mask = 1ULL << (insn->size-1);
 379         bits = mask | (mask-1);
 380
 381         if (left & mask)
 382                 left |= ~bits;
 383         if (right & mask)
 384                 right |= ~bits;
 385         ul = left & bits;
 386         ur = right & bits;
 387
 388         switch (insn->opcode) {
 389         case OP_ADD:
 390                 res = left + right;
 391                 break;
 392         case OP_SUB:
 393                 res = left - right;
 394                 break;
 395         case OP_MULU:
 396                 res = ul * ur;
 397                 break;
 398         case OP_MULS:
 399                 res = left * right;
 400                 break;
 401         case OP_DIVU:
 402                 if (!ur)
 403                         return 0;
 404                 res = ul / ur;
 405                 break;
 406         case OP_DIVS:
 407                 if (!right)
 408                         return 0;
 409                 res = left / right;
 410                 break;
 411         case OP_MODU:
 412                 if (!ur)
 413                         return 0;
 414                 res = ul % ur;
 415                 break;
 416         case OP_MODS:
 417                 if (!right)
 418                         return 0;
 419                 res = left % right;
 420                 break;
 421         case OP_SHL:
 422                 res = left << right;
 423                 break;
 424         case OP_LSR:
 425                 res = ul >> ur;
 426                 break;
 427         case OP_ASR:
 428                 res = left >> right;
 429                 break;
 430        /* Logical */
 431         case OP_AND:
 432                 res = left & right;
 433                 break;
 434         case OP_OR:
 435                 res = left | right;
 436                 break;
 437         case OP_XOR:
 438                 res = left ^ right;
 439                 break;
 440         case OP_AND_BOOL:
 441                 res = left && right;
 442                 break;
 443         case OP_OR_BOOL:
 444                 res = left || right;
 445                 break;
 446
 447         /* Binary comparison */
 448         case OP_SET_EQ:
 449                 res = left == right;
 450                 break;
 451         case OP_SET_NE:
 452                 res = left != right;
 453                 break;
 454         case OP_SET_LE:
 455                 res = left <= right;
 456                 break;
 457         case OP_SET_GE:
 458                 res = left >= right;
 459                 break;
 460         case OP_SET_LT:
 461                 res = left < right;
 462                 break;
 463         case OP_SET_GT:
 464                 res = left > right;
 465                 break;
 466         case OP_SET_B:
 467                 res = ul < ur;
 468                 break;
 469         case OP_SET_A:
 470                 res = ul > ur;
 471                 break;
 472         case OP_SET_BE:
 473                 res = ul <= ur;
 474                 break;
 475         case OP_SET_AE:
 476                 res = ul >= ur;
 477                 break;
 478         default:
 479                 return 0;
 480         }
 481         res &= bits;
 482
 483         replace_with_pseudo(insn, value_pseudo(res));
 484         return REPEAT_CSE;
 485 }
 486
 487 static int simplify_binop(struct instruction *insn)
 488 {
 489         if (dead_insn(insn, &insn->src1, &insn->src2, NULL))
 490                 return REPEAT_CSE;
 491         if (constant(insn->src1)) {
 492                 if (constant(insn->src2))
 493                         return simplify_constant_binop(insn);
 494                 return simplify_constant_leftside(insn);
 495         }
 496         if (constant(insn->src2))
 497                 return simplify_constant_rightside(insn);
 498         return 0;
 499 }
 500
 501 static void switch_pseudo(struct instruction *insn1, pseudo_t *pp1, struct instruction *insn2, pseudo_t *pp2)
 502 {
 503         pseudo_t p1 = *pp1, p2 = *pp2;
 504
 505         use_pseudo(insn1, p2, pp1);
 506         use_pseudo(insn2, p1, pp2);
 507         remove_usage(p1, pp1);
 508         remove_usage(p2, pp2);
 509 }
 510
 511 static int canonical_order(pseudo_t p1, pseudo_t p2)
 512 {
 513         /* symbol/constants on the right */
 514         if (p1->type == PSEUDO_VAL)
 515                 return p2->type == PSEUDO_VAL;
 516
 517         if (p1->type == PSEUDO_SYM)
 518                 return p2->type == PSEUDO_SYM || p2->type == PSEUDO_VAL;
 519
 520         return 1;
 521 }
 522
 523 static int simplify_commutative_binop(struct instruction *insn)
 524 {
 525         if (!canonical_order(insn->src1, insn->src2)) {
 526                 switch_pseudo(insn, &insn->src1, insn, &insn->src2);
 527                 return REPEAT_CSE;
 528         }
 529         return 0;
 530 }
 531
 532 static inline int simple_pseudo(pseudo_t pseudo)
 533 {
 534         return pseudo->type == PSEUDO_VAL || pseudo->type == PSEUDO_SYM;
 535 }
 536
 537 static int simplify_associative_binop(struct instruction *insn)
 538 {
 539         struct instruction *def;
 540         pseudo_t pseudo = insn->src1;
 541
 542         if (!simple_pseudo(insn->src2))
 543                 return 0;
 544         if (pseudo->type != PSEUDO_REG)
 545                 return 0;
 546         def = pseudo->def;
 547         if (def == insn)
 548                 return 0;
 549         if (def->opcode != insn->opcode)
 550                 return 0;
 551         if (!simple_pseudo(def->src2))
 552                 return 0;
 553         if (ptr_list_size((struct ptr_list *)def->target->users) != 1)
 554                 return 0;
 555         switch_pseudo(def, &def->src1, insn, &insn->src2);
 556         return REPEAT_CSE;
 557 }
 558
 559 static int simplify_constant_unop(struct instruction *insn)
 560 {
 561         long long val = insn->src1->value;
 562         long long res, mask;
 563
 564         switch (insn->opcode) {
 565         case OP_NOT:
 566                 res = ~val;
 567                 break;
 568         case OP_NEG:
 569                 res = -val;
 570                 break;
 571         default:
 572                 return 0;
 573         }
 574         mask = 1ULL << (insn->size-1);
 575         res &= mask | (mask-1);
 576
 577         replace_with_pseudo(insn, value_pseudo(res));
 578         return REPEAT_CSE;
 579 }
 580
 581 static int simplify_unop(struct instruction *insn)
 582 {
 583         if (dead_insn(insn, &insn->src1, NULL, NULL))
 584                 return REPEAT_CSE;
 585         if (constant(insn->src1))
 586                 return simplify_constant_unop(insn);
 587         return 0;
 588 }
 589
 590 static int simplify_one_memop(struct instruction *insn, pseudo_t orig)
 591 {
 592         pseudo_t addr = insn->src;
 593         pseudo_t new, off;
 594
 595         if (addr->type == PSEUDO_REG) {
 596                 struct instruction *def = addr->def;
 597                 if (def->opcode == OP_SYMADDR && def->src) {
 598                         kill_use(&insn->src);
 599                         use_pseudo(insn, def->src, &insn->src);
 600                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 601                 }
 602                 if (def->opcode == OP_ADD) {
 603                         new = def->src1;
 604                         off = def->src2;
 605                         if (constant(off))
 606                                 goto offset;
 607                         new = off;
 608                         off = def->src1;
 609                         if (constant(off))
 610                                 goto offset;
 611                         return 0;
 612                 }
 613         }
 614         return 0;
 615
 616 offset:
 617         /* Invalid code */
 618         if (new == orig) {
 619                 if (new == VOID)
 620                         return 0;
 621                 new = VOID;
 622                 warning(insn->pos, "crazy programmer");
 623         }
 624         insn->offset += off->value;
 625         use_pseudo(insn, new, &insn->src);
 626         remove_usage(addr, &insn->src);
 627         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 628 }
 629
 630 /*
 631  * We walk the whole chain of adds/subs backwards. That's not
 632  * only more efficient, but it allows us to find loops.
 633  */
 634 static int simplify_memop(struct instruction *insn)
 635 {
 636         int one, ret = 0;
 637         pseudo_t orig = insn->src;
 638
 639         do {
 640                 one = simplify_one_memop(insn, orig);
 641                 ret |= one;
 642         } while (one);
 643         return ret;
 644 }
 645
 646 static long long get_cast_value(long long val, int old_size, int new_size, int sign)
 647 {
 648         long long mask;
 649
 650         if (sign && new_size > old_size) {
 651                 mask = 1 << (old_size-1);
 652                 if (val & mask)
 653                         val |= ~(mask | (mask-1));
 654         }
 655         mask = 1 << (new_size-1);
 656         return val & (mask | (mask-1));
 657 }
 658
 659 static int simplify_cast(struct instruction *insn)
 660 {
 661         struct symbol *orig_type;
 662         int orig_size, size;
 663         pseudo_t src;
 664
 665         if (dead_insn(insn, &insn->src, NULL, NULL))
 666                 return REPEAT_CSE;
 667
 668         orig_type = insn->orig_type;
 669         if (!orig_type)
 670                 return 0;
 671
 672         /* Keep casts with pointer on either side (not only case of OP_PTRCAST) */
 673         if (is_ptr_type(orig_type) || is_ptr_type(insn->type))
 674                 return 0;
 675
 676         orig_size = orig_type->bit_size;
 677         size = insn->size;
 678         src = insn->src;
 679
 680         /* A cast of a constant? */
 681         if (constant(src)) {
 682                 int sign = orig_type->ctype.modifiers & MOD_SIGNED;
 683                 long long val = get_cast_value(src->value, orig_size, size, sign);
 684                 src = value_pseudo(val);
 685                 goto simplify;
 686         }
 687
 688         /* A cast of a "and" might be a no-op.. */
 689         if (src->type == PSEUDO_REG) {
 690                 struct instruction *def = src->def;
 691                 if (def->opcode == OP_AND && def->size >= size) {
 692                         pseudo_t val = def->src2;
 693                         if (val->type == PSEUDO_VAL) {
 694                                 unsigned long long value = val->value;
 695                                 if (!(value >> (size-1)))
 696                                         goto simplify;
 697                         }
 698                 }
 699         }
 700
 701         if (size == orig_size) {
 702                 int op = (orig_type->ctype.modifiers & MOD_SIGNED) ? OP_SCAST : OP_CAST;
 703                 if (insn->opcode == op)
 704                         goto simplify;
 705         }
 706
 707         return 0;
 708
 709 simplify:
 710         return replace_with_pseudo(insn, src);
 711 }
 712
 713 static int simplify_select(struct instruction *insn)
 714 {
 715         pseudo_t cond, src1, src2;
 716
 717         if (dead_insn(insn, &insn->src1, &insn->src2, &insn->src3))
 718                 return REPEAT_CSE;
 719
 720         cond = insn->src1;
 721         src1 = insn->src2;
 722         src2 = insn->src3;
 723         if (constant(cond) || src1 == src2) {
 724                 pseudo_t *kill, take;
 725                 kill_use(&insn->src1);
 726                 take = cond->value ? src1 : src2;
 727                 kill = cond->value ? &insn->src3 : &insn->src2;
 728                 kill_use(kill);
 729                 replace_with_pseudo(insn, take);
 730                 return REPEAT_CSE;
 731         }
 732         if (constant(src1) && constant(src2)) {
 733                 long long val1 = src1->value;
 734                 long long val2 = src2->value;
 735
 736                 /* The pair 0/1 is special - replace with SETNE/SETEQ */
 737                 if ((val1 | val2) == 1) {
 738                         int opcode = OP_SET_EQ;
 739                         if (val1) {
 740                                 src1 = src2;
 741                                 opcode = OP_SET_NE;
 742                         }
 743                         insn->opcode = opcode;
 744                         /* insn->src1 is already cond */
 745                         insn->src2 = src1; /* Zero */
 746                         return REPEAT_CSE;
 747                 }
 748         }
 749         return 0;
 750 }
 751
 752 static int is_in_range(pseudo_t src, long long low, long long high)
 753 {
 754         long long value;
 755
 756         switch (src->type) {
 757         case PSEUDO_VAL:
 758                 value = src->value;
 759                 return value >= low && value <= high;
 760         default:
 761                 return 0;
 762         }
 763 }
 764
 765 static int simplify_range(struct instruction *insn)
 766 {
 767         pseudo_t src1, src2, src3;
 768
 769         src1 = insn->src1;
 770         src2 = insn->src2;
 771         src3 = insn->src3;
 772         if (src2->type != PSEUDO_VAL || src3->type != PSEUDO_VAL)
 773                 return 0;
 774         if (is_in_range(src1, src2->value, src3->value)) {
 775                 kill_instruction(insn);
 776                 return REPEAT_CSE;
 777         }
 778         return 0;
 779 }
 780
 781 /*
 782  * Simplify "set_ne/eq $0 + br"
 783  */
 784 static int simplify_cond_branch(struct instruction *br, pseudo_t cond, struct instruction *def, pseudo_t *pp)
 785 {
 786         use_pseudo(br, *pp, &br->cond);
 787         remove_usage(cond, &br->cond);
 788         if (def->opcode == OP_SET_EQ) {
 789                 struct basic_block *true = br->bb_true;
 790                 struct basic_block *false = br->bb_false;
 791                 br->bb_false = true;
 792                 br->bb_true = false;
 793         }
 794         return REPEAT_CSE;
 795 }
 796
 797 static int simplify_branch(struct instruction *insn)
 798 {
 799         pseudo_t cond = insn->cond;
 800
 801         if (!cond)
 802                 return 0;
 803
 804         /* Constant conditional */
 805         if (constant(cond)) {
 806                 insert_branch(insn->bb, insn, cond->value ? insn->bb_true : insn->bb_false);
 807                 return REPEAT_CSE;
 808         }
 809
 810         /* Same target? */
 811         if (insn->bb_true == insn->bb_false) {
 812                 struct basic_block *bb = insn->bb;
 813                 struct basic_block *target = insn->bb_false;
 814                 remove_bb_from_list(&target->parents, bb, 1);
 815                 remove_bb_from_list(&bb->children, target, 1);
 816                 insn->bb_false = NULL;
 817                 kill_use(&insn->cond);
 818                 insn->cond = NULL;
 819                 return REPEAT_CSE;
 820         }
 821
 822         /* Conditional on a SETNE $0 or SETEQ $0 */
 823         if (cond->type == PSEUDO_REG) {
 824                 struct instruction *def = cond->def;
 825
 826                 if (def->opcode == OP_SET_NE || def->opcode == OP_SET_EQ) {
 827                         if (constant(def->src1) && !def->src1->value)
 828                                 return simplify_cond_branch(insn, cond, def, &def->src2);
 829                         if (constant(def->src2) && !def->src2->value)
 830                                 return simplify_cond_branch(insn, cond, def, &def->src1);
 831                 }
 832                 if (def->opcode == OP_SEL) {
 833                         if (constant(def->src2) && constant(def->src3)) {
 834                                 long long val1 = def->src2->value;
 835                                 long long val2 = def->src3->value;
 836                                 if (!val1 && !val2) {
 837                                         insert_branch(insn->bb, insn, insn->bb_false);
 838                                         return REPEAT_CSE;
 839                                 }
 840                                 if (val1 && val2) {
 841                                         insert_branch(insn->bb, insn, insn->bb_true);
 842                                         return REPEAT_CSE;
 843                                 }
 844                                 if (val2) {
 845                                         struct basic_block *true = insn->bb_true;
 846                                         struct basic_block *false = insn->bb_false;
 847                                         insn->bb_false = true;
 848                                         insn->bb_true = false;
 849                                 }
 850                                 use_pseudo(insn, def->src1, &insn->cond);
 851                                 remove_usage(cond, &insn->cond);
 852                                 return REPEAT_CSE;
 853                         }
 854                 }
 855                 if (def->opcode == OP_CAST || def->opcode == OP_SCAST) {
 856                         int orig_size = def->orig_type ? def->orig_type->bit_size : 0;
 857                         if (def->size > orig_size) {
 858                                 use_pseudo(insn, def->src, &insn->cond);
 859                                 remove_usage(cond, &insn->cond);
 860                                 return REPEAT_CSE;
 861                         }
 862                 }
 863         }
 864         return 0;
 865 }
 866
 867 static int simplify_switch(struct instruction *insn)
 868 {
 869         pseudo_t cond = insn->cond;
 870         long long val;
 871         struct multijmp *jmp;
 872
 873         if (!constant(cond))
 874                 return 0;
 875         val = insn->cond->value;
 876
 877         FOR_EACH_PTR(insn->multijmp_list, jmp) {
 878                 /* Default case */
 879                 if (jmp->begin > jmp->end)
 880                         goto found;
 881                 if (val >= jmp->begin && val <= jmp->end)
 882                         goto found;
 883         } END_FOR_EACH_PTR(jmp);
 884         warning(insn->pos, "Impossible case statement");
 885         return 0;
 886
 887 found:
 888         insert_branch(insn->bb, insn, jmp->target);
 889         return REPEAT_CSE;
 890 }
 891
 892 int simplify_instruction(struct instruction *insn)
 893 {
 894         if (!insn->bb)
 895                 return 0;
 896         switch (insn->opcode) {
 897         case OP_ADD: case OP_MULS:
 898         case OP_AND: case OP_OR: case OP_XOR:
 899         case OP_AND_BOOL: case OP_OR_BOOL:
 900                 if (simplify_binop(insn))
 901                         return REPEAT_CSE;
 902                 if (simplify_commutative_binop(insn))
 903                         return REPEAT_CSE;
 904                 return simplify_associative_binop(insn);
 905
 906         case OP_MULU:
 907         case OP_SET_EQ: case OP_SET_NE:
 908                 if (simplify_binop(insn))
 909                         return REPEAT_CSE;
 910                 return simplify_commutative_binop(insn);
 911
 912         case OP_SUB:
 913         case OP_DIVU: case OP_DIVS:
 914         case OP_MODU: case OP_MODS:
 915         case OP_SHL:
 916         case OP_LSR: case OP_ASR:
 917         case OP_SET_LE: case OP_SET_GE:
 918         case OP_SET_LT: case OP_SET_GT:
 919         case OP_SET_B:  case OP_SET_A:
 920         case OP_SET_BE: case OP_SET_AE:
 921                 return simplify_binop(insn);
 922
 923         case OP_NOT: case OP_NEG:
 924                 return simplify_unop(insn);
 925         case OP_LOAD: case OP_STORE:
 926                 return simplify_memop(insn);
 927         case OP_SYMADDR:
 928                 if (dead_insn(insn, NULL, NULL, NULL))
 929                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 930                 return replace_with_pseudo(insn, insn->symbol);
 931         case OP_CAST:
 932         case OP_SCAST:
 933         case OP_FPCAST:
 934         case OP_PTRCAST:
 935                 return simplify_cast(insn);
 936         case OP_PHI:
 937                 if (dead_insn(insn, NULL, NULL, NULL)) {
 938                         clear_phi(insn);
 939                         return REPEAT_CSE;
 940                 }
 941                 return clean_up_phi(insn);
 942         case OP_PHISOURCE:
 943                 if (dead_insn(insn, &insn->phi_src, NULL, NULL))
 944                         return REPEAT_CSE;
 945                 break;
 946         case OP_SEL:
 947                 return simplify_select(insn);
 948         case OP_BR:
 949                 return simplify_branch(insn);
 950         case OP_SWITCH:
 951                 return simplify_switch(insn);
 952         case OP_RANGE:
 953                 return simplify_range(insn);
 954         }
 955         return 0;
 956 }