tcg/optimize.c

   1 /*
   2  * Optimizations for Tiny Code Generator for QEMU
   3  *
   4  * Copyright (c) 2010 Samsung Electronics.
   5  * Contributed by Kirill Batuzov <batuzovk@ispras.ru>
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "config.h"
  27
  28 #include <stdlib.h>
  29 #include <stdio.h>
  30
  31 #include "qemu-common.h"
  32 #include "tcg-op.h"
  33
  34 #define CASE_OP_32_64(x)                        \
  35         glue(glue(case INDEX_op_, x), _i32):    \
  36         glue(glue(case INDEX_op_, x), _i64)
  37
  38 typedef enum {
  39     TCG_TEMP_UNDEF = 0,
  40     TCG_TEMP_CONST,
  41     TCG_TEMP_COPY,
  42 } tcg_temp_state;
  43
  44 struct tcg_temp_info {
  45     tcg_temp_state state;
  46     uint16_t prev_copy;
  47     uint16_t next_copy;
  48     tcg_target_ulong val;
  49     tcg_target_ulong mask;
  50 };
  51
  52 static struct tcg_temp_info temps[TCG_MAX_TEMPS];
  53
  54 /* Reset TEMP's state to TCG_TEMP_UNDEF.  If TEMP only had one copy, remove
  55    the copy flag from the left temp.  */
  56 static void reset_temp(TCGArg temp)
  57 {
  58     if (temps[temp].state == TCG_TEMP_COPY) {
  59         if (temps[temp].prev_copy == temps[temp].next_copy) {
  60             temps[temps[temp].next_copy].state = TCG_TEMP_UNDEF;
  61         } else {
  62             temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
  63             temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
  64         }
  65     }
  66     temps[temp].state = TCG_TEMP_UNDEF;
  67     temps[temp].mask = -1;
  68 }
  69
  70 static TCGOp *insert_op_before(TCGContext *s, TCGOp *old_op,
  71                                 TCGOpcode opc, int nargs)
  72 {
  73     int oi = s->gen_next_op_idx;
  74     int pi = s->gen_next_parm_idx;
  75     int prev = old_op->prev;
  76     int next = old_op - s->gen_op_buf;
  77     TCGOp *new_op;
  78
  79     tcg_debug_assert(oi < OPC_BUF_SIZE);
  80     tcg_debug_assert(pi + nargs <= OPPARAM_BUF_SIZE);
  81     s->gen_next_op_idx = oi + 1;
  82     s->gen_next_parm_idx = pi + nargs;
  83
  84     new_op = &s->gen_op_buf[oi];
  85     *new_op = (TCGOp){
  86         .opc = opc,
  87         .args = pi,
  88         .prev = prev,
  89         .next = next
  90     };
  91     if (prev >= 0) {
  92         s->gen_op_buf[prev].next = oi;
  93     } else {
  94         s->gen_first_op_idx = oi;
  95     }
  96     old_op->prev = oi;
  97
  98     return new_op;
  99 }
 100
 101 /* Reset all temporaries, given that there are NB_TEMPS of them.  */
 102 static void reset_all_temps(int nb_temps)
 103 {
 104     int i;
 105     for (i = 0; i < nb_temps; i++) {
 106         temps[i].state = TCG_TEMP_UNDEF;
 107         temps[i].mask = -1;
 108     }
 109 }
 110
 111 static int op_bits(TCGOpcode op)
 112 {
 113     const TCGOpDef *def = &tcg_op_defs[op];
 114     return def->flags & TCG_OPF_64BIT ? 64 : 32;
 115 }
 116
 117 static TCGOpcode op_to_mov(TCGOpcode op)
 118 {
 119     switch (op_bits(op)) {
 120     case 32:
 121         return INDEX_op_mov_i32;
 122     case 64:
 123         return INDEX_op_mov_i64;
 124     default:
 125         fprintf(stderr, "op_to_mov: unexpected return value of "
 126                 "function op_bits.\n");
 127         tcg_abort();
 128     }
 129 }
 130
 131 static TCGOpcode op_to_movi(TCGOpcode op)
 132 {
 133     switch (op_bits(op)) {
 134     case 32:
 135         return INDEX_op_movi_i32;
 136     case 64:
 137         return INDEX_op_movi_i64;
 138     default:
 139         fprintf(stderr, "op_to_movi: unexpected return value of "
 140                 "function op_bits.\n");
 141         tcg_abort();
 142     }
 143 }
 144
 145 static TCGArg find_better_copy(TCGContext *s, TCGArg temp)
 146 {
 147     TCGArg i;
 148
 149     /* If this is already a global, we can't do better. */
 150     if (temp < s->nb_globals) {
 151         return temp;
 152     }
 153
 154     /* Search for a global first. */
 155     for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
 156         if (i < s->nb_globals) {
 157             return i;
 158         }
 159     }
 160
 161     /* If it is a temp, search for a temp local. */
 162     if (!s->temps[temp].temp_local) {
 163         for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
 164             if (s->temps[i].temp_local) {
 165                 return i;
 166             }
 167         }
 168     }
 169
 170     /* Failure to find a better representation, return the same temp. */
 171     return temp;
 172 }
 173
 174 static bool temps_are_copies(TCGArg arg1, TCGArg arg2)
 175 {
 176     TCGArg i;
 177
 178     if (arg1 == arg2) {
 179         return true;
 180     }
 181
 182     if (temps[arg1].state != TCG_TEMP_COPY
 183         || temps[arg2].state != TCG_TEMP_COPY) {
 184         return false;
 185     }
 186
 187     for (i = temps[arg1].next_copy ; i != arg1 ; i = temps[i].next_copy) {
 188         if (i == arg2) {
 189             return true;
 190         }
 191     }
 192
 193     return false;
 194 }
 195
 196 static void tcg_opt_gen_mov(TCGContext *s, TCGOp *op, TCGArg *args,
 197                             TCGOpcode old_op, TCGArg dst, TCGArg src)
 198 {
 199     TCGOpcode new_op = op_to_mov(old_op);
 200     tcg_target_ulong mask;
 201
 202     op->opc = new_op;
 203
 204     reset_temp(dst);
 205     mask = temps[src].mask;
 206     if (TCG_TARGET_REG_BITS > 32 && new_op == INDEX_op_mov_i32) {
 207         /* High bits of the destination are now garbage.  */
 208         mask |= ~0xffffffffull;
 209     }
 210     temps[dst].mask = mask;
 211
 212     assert(temps[src].state != TCG_TEMP_CONST);
 213
 214     if (s->temps[src].type == s->temps[dst].type) {
 215         if (temps[src].state != TCG_TEMP_COPY) {
 216             temps[src].state = TCG_TEMP_COPY;
 217             temps[src].next_copy = src;
 218             temps[src].prev_copy = src;
 219         }
 220         temps[dst].state = TCG_TEMP_COPY;
 221         temps[dst].next_copy = temps[src].next_copy;
 222         temps[dst].prev_copy = src;
 223         temps[temps[dst].next_copy].prev_copy = dst;
 224         temps[src].next_copy = dst;
 225     }
 226
 227     args[0] = dst;
 228     args[1] = src;
 229 }
 230
 231 static void tcg_opt_gen_movi(TCGContext *s, TCGOp *op, TCGArg *args,
 232                              TCGOpcode old_op, TCGArg dst, TCGArg val)
 233 {
 234     TCGOpcode new_op = op_to_movi(old_op);
 235     tcg_target_ulong mask;
 236
 237     op->opc = new_op;
 238
 239     reset_temp(dst);
 240     temps[dst].state = TCG_TEMP_CONST;
 241     temps[dst].val = val;
 242     mask = val;
 243     if (TCG_TARGET_REG_BITS > 32 && new_op == INDEX_op_mov_i32) {
 244         /* High bits of the destination are now garbage.  */
 245         mask |= ~0xffffffffull;
 246     }
 247     temps[dst].mask = mask;
 248
 249     args[0] = dst;
 250     args[1] = val;
 251 }
 252
 253 static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
 254 {
 255     uint64_t l64, h64;
 256
 257     switch (op) {
 258     CASE_OP_32_64(add):
 259         return x + y;
 260
 261     CASE_OP_32_64(sub):
 262         return x - y;
 263
 264     CASE_OP_32_64(mul):
 265         return x * y;
 266
 267     CASE_OP_32_64(and):
 268         return x & y;
 269
 270     CASE_OP_32_64(or):
 271         return x | y;
 272
 273     CASE_OP_32_64(xor):
 274         return x ^ y;
 275
 276     case INDEX_op_shl_i32:
 277         return (uint32_t)x << (y & 31);
 278
 279     case INDEX_op_shl_i64:
 280         return (uint64_t)x << (y & 63);
 281
 282     case INDEX_op_shr_i32:
 283         return (uint32_t)x >> (y & 31);
 284
 285     case INDEX_op_trunc_shr_i32:
 286     case INDEX_op_shr_i64:
 287         return (uint64_t)x >> (y & 63);
 288
 289     case INDEX_op_sar_i32:
 290         return (int32_t)x >> (y & 31);
 291
 292     case INDEX_op_sar_i64:
 293         return (int64_t)x >> (y & 63);
 294
 295     case INDEX_op_rotr_i32:
 296         return ror32(x, y & 31);
 297
 298     case INDEX_op_rotr_i64:
 299         return ror64(x, y & 63);
 300
 301     case INDEX_op_rotl_i32:
 302         return rol32(x, y & 31);
 303
 304     case INDEX_op_rotl_i64:
 305         return rol64(x, y & 63);
 306
 307     CASE_OP_32_64(not):
 308         return ~x;
 309
 310     CASE_OP_32_64(neg):
 311         return -x;
 312
 313     CASE_OP_32_64(andc):
 314         return x & ~y;
 315
 316     CASE_OP_32_64(orc):
 317         return x | ~y;
 318
 319     CASE_OP_32_64(eqv):
 320         return ~(x ^ y);
 321
 322     CASE_OP_32_64(nand):
 323         return ~(x & y);
 324
 325     CASE_OP_32_64(nor):
 326         return ~(x | y);
 327
 328     CASE_OP_32_64(ext8s):
 329         return (int8_t)x;
 330
 331     CASE_OP_32_64(ext16s):
 332         return (int16_t)x;
 333
 334     CASE_OP_32_64(ext8u):
 335         return (uint8_t)x;
 336
 337     CASE_OP_32_64(ext16u):
 338         return (uint16_t)x;
 339
 340     case INDEX_op_ext32s_i64:
 341         return (int32_t)x;
 342
 343     case INDEX_op_ext32u_i64:
 344         return (uint32_t)x;
 345
 346     case INDEX_op_muluh_i32:
 347         return ((uint64_t)(uint32_t)x * (uint32_t)y) >> 32;
 348     case INDEX_op_mulsh_i32:
 349         return ((int64_t)(int32_t)x * (int32_t)y) >> 32;
 350
 351     case INDEX_op_muluh_i64:
 352         mulu64(&l64, &h64, x, y);
 353         return h64;
 354     case INDEX_op_mulsh_i64:
 355         muls64(&l64, &h64, x, y);
 356         return h64;
 357
 358     case INDEX_op_div_i32:
 359         /* Avoid crashing on divide by zero, otherwise undefined.  */
 360         return (int32_t)x / ((int32_t)y ? : 1);
 361     case INDEX_op_divu_i32:
 362         return (uint32_t)x / ((uint32_t)y ? : 1);
 363     case INDEX_op_div_i64:
 364         return (int64_t)x / ((int64_t)y ? : 1);
 365     case INDEX_op_divu_i64:
 366         return (uint64_t)x / ((uint64_t)y ? : 1);
 367
 368     case INDEX_op_rem_i32:
 369         return (int32_t)x % ((int32_t)y ? : 1);
 370     case INDEX_op_remu_i32:
 371         return (uint32_t)x % ((uint32_t)y ? : 1);
 372     case INDEX_op_rem_i64:
 373         return (int64_t)x % ((int64_t)y ? : 1);
 374     case INDEX_op_remu_i64:
 375         return (uint64_t)x % ((uint64_t)y ? : 1);
 376
 377     default:
 378         fprintf(stderr,
 379                 "Unrecognized operation %d in do_constant_folding.\n", op);
 380         tcg_abort();
 381     }
 382 }
 383
 384 static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
 385 {
 386     TCGArg res = do_constant_folding_2(op, x, y);
 387     if (op_bits(op) == 32) {
 388         res &= 0xffffffff;
 389     }
 390     return res;
 391 }
 392
 393 static bool do_constant_folding_cond_32(uint32_t x, uint32_t y, TCGCond c)
 394 {
 395     switch (c) {
 396     case TCG_COND_EQ:
 397         return x == y;
 398     case TCG_COND_NE:
 399         return x != y;
 400     case TCG_COND_LT:
 401         return (int32_t)x < (int32_t)y;
 402     case TCG_COND_GE:
 403         return (int32_t)x >= (int32_t)y;
 404     case TCG_COND_LE:
 405         return (int32_t)x <= (int32_t)y;
 406     case TCG_COND_GT:
 407         return (int32_t)x > (int32_t)y;
 408     case TCG_COND_LTU:
 409         return x < y;
 410     case TCG_COND_GEU:
 411         return x >= y;
 412     case TCG_COND_LEU:
 413         return x <= y;
 414     case TCG_COND_GTU:
 415         return x > y;
 416     default:
 417         tcg_abort();
 418     }
 419 }
 420
 421 static bool do_constant_folding_cond_64(uint64_t x, uint64_t y, TCGCond c)
 422 {
 423     switch (c) {
 424     case TCG_COND_EQ:
 425         return x == y;
 426     case TCG_COND_NE:
 427         return x != y;
 428     case TCG_COND_LT:
 429         return (int64_t)x < (int64_t)y;
 430     case TCG_COND_GE:
 431         return (int64_t)x >= (int64_t)y;
 432     case TCG_COND_LE:
 433         return (int64_t)x <= (int64_t)y;
 434     case TCG_COND_GT:
 435         return (int64_t)x > (int64_t)y;
 436     case TCG_COND_LTU:
 437         return x < y;
 438     case TCG_COND_GEU:
 439         return x >= y;
 440     case TCG_COND_LEU:
 441         return x <= y;
 442     case TCG_COND_GTU:
 443         return x > y;
 444     default:
 445         tcg_abort();
 446     }
 447 }
 448
 449 static bool do_constant_folding_cond_eq(TCGCond c)
 450 {
 451     switch (c) {
 452     case TCG_COND_GT:
 453     case TCG_COND_LTU:
 454     case TCG_COND_LT:
 455     case TCG_COND_GTU:
 456     case TCG_COND_NE:
 457         return 0;
 458     case TCG_COND_GE:
 459     case TCG_COND_GEU:
 460     case TCG_COND_LE:
 461     case TCG_COND_LEU:
 462     case TCG_COND_EQ:
 463         return 1;
 464     default:
 465         tcg_abort();
 466     }
 467 }
 468
 469 /* Return 2 if the condition can't be simplified, and the result
 470    of the condition (0 or 1) if it can */
 471 static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
 472                                        TCGArg y, TCGCond c)
 473 {
 474     if (temps[x].state == TCG_TEMP_CONST && temps[y].state == TCG_TEMP_CONST) {
 475         switch (op_bits(op)) {
 476         case 32:
 477             return do_constant_folding_cond_32(temps[x].val, temps[y].val, c);
 478         case 64:
 479             return do_constant_folding_cond_64(temps[x].val, temps[y].val, c);
 480         default:
 481             tcg_abort();
 482         }
 483     } else if (temps_are_copies(x, y)) {
 484         return do_constant_folding_cond_eq(c);
 485     } else if (temps[y].state == TCG_TEMP_CONST && temps[y].val == 0) {
 486         switch (c) {
 487         case TCG_COND_LTU:
 488             return 0;
 489         case TCG_COND_GEU:
 490             return 1;
 491         default:
 492             return 2;
 493         }
 494     } else {
 495         return 2;
 496     }
 497 }
 498
 499 /* Return 2 if the condition can't be simplified, and the result
 500    of the condition (0 or 1) if it can */
 501 static TCGArg do_constant_folding_cond2(TCGArg *p1, TCGArg *p2, TCGCond c)
 502 {
 503     TCGArg al = p1[0], ah = p1[1];
 504     TCGArg bl = p2[0], bh = p2[1];
 505
 506     if (temps[bl].state == TCG_TEMP_CONST
 507         && temps[bh].state == TCG_TEMP_CONST) {
 508         uint64_t b = ((uint64_t)temps[bh].val << 32) | (uint32_t)temps[bl].val;
 509
 510         if (temps[al].state == TCG_TEMP_CONST
 511             && temps[ah].state == TCG_TEMP_CONST) {
 512             uint64_t a;
 513             a = ((uint64_t)temps[ah].val << 32) | (uint32_t)temps[al].val;
 514             return do_constant_folding_cond_64(a, b, c);
 515         }
 516         if (b == 0) {
 517             switch (c) {
 518             case TCG_COND_LTU:
 519                 return 0;
 520             case TCG_COND_GEU:
 521                 return 1;
 522             default:
 523                 break;
 524             }
 525         }
 526     }
 527     if (temps_are_copies(al, bl) && temps_are_copies(ah, bh)) {
 528         return do_constant_folding_cond_eq(c);
 529     }
 530     return 2;
 531 }
 532
 533 static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2)
 534 {
 535     TCGArg a1 = *p1, a2 = *p2;
 536     int sum = 0;
 537     sum += temps[a1].state == TCG_TEMP_CONST;
 538     sum -= temps[a2].state == TCG_TEMP_CONST;
 539
 540     /* Prefer the constant in second argument, and then the form
 541        op a, a, b, which is better handled on non-RISC hosts. */
 542     if (sum > 0 || (sum == 0 && dest == a2)) {
 543         *p1 = a2;
 544         *p2 = a1;
 545         return true;
 546     }
 547     return false;
 548 }
 549
 550 static bool swap_commutative2(TCGArg *p1, TCGArg *p2)
 551 {
 552     int sum = 0;
 553     sum += temps[p1[0]].state == TCG_TEMP_CONST;
 554     sum += temps[p1[1]].state == TCG_TEMP_CONST;
 555     sum -= temps[p2[0]].state == TCG_TEMP_CONST;
 556     sum -= temps[p2[1]].state == TCG_TEMP_CONST;
 557     if (sum > 0) {
 558         TCGArg t;
 559         t = p1[0], p1[0] = p2[0], p2[0] = t;
 560         t = p1[1], p1[1] = p2[1], p2[1] = t;
 561         return true;
 562     }
 563     return false;
 564 }
 565
 566 /* Propagate constants and copies, fold constant expressions. */
 567 static void tcg_constant_folding(TCGContext *s)
 568 {
 569     int oi, oi_next, nb_temps, nb_globals;
 570
 571     /* Array VALS has an element for each temp.
 572        If this temp holds a constant then its value is kept in VALS' element.
 573        If this temp is a copy of other ones then the other copies are
 574        available through the doubly linked circular list. */
 575
 576     nb_temps = s->nb_temps;
 577     nb_globals = s->nb_globals;
 578     reset_all_temps(nb_temps);
 579
 580     for (oi = s->gen_first_op_idx; oi >= 0; oi = oi_next) {
 581         tcg_target_ulong mask, partmask, affected;
 582         int nb_oargs, nb_iargs, i;
 583         TCGArg tmp;
 584
 585         TCGOp * const op = &s->gen_op_buf[oi];
 586         TCGArg * const args = &s->gen_opparam_buf[op->args];
 587         TCGOpcode opc = op->opc;
 588         const TCGOpDef *def = &tcg_op_defs[opc];
 589
 590         oi_next = op->next;
 591         if (opc == INDEX_op_call) {
 592             nb_oargs = op->callo;
 593             nb_iargs = op->calli;
 594         } else {
 595             nb_oargs = def->nb_oargs;
 596             nb_iargs = def->nb_iargs;
 597         }
 598
 599         /* Do copy propagation */
 600         for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
 601             if (temps[args[i]].state == TCG_TEMP_COPY) {
 602                 args[i] = find_better_copy(s, args[i]);
 603             }
 604         }
 605
 606         /* For commutative operations make constant second argument */
 607         switch (opc) {
 608         CASE_OP_32_64(add):
 609         CASE_OP_32_64(mul):
 610         CASE_OP_32_64(and):
 611         CASE_OP_32_64(or):
 612         CASE_OP_32_64(xor):
 613         CASE_OP_32_64(eqv):
 614         CASE_OP_32_64(nand):
 615         CASE_OP_32_64(nor):
 616         CASE_OP_32_64(muluh):
 617         CASE_OP_32_64(mulsh):
 618             swap_commutative(args[0], &args[1], &args[2]);
 619             break;
 620         CASE_OP_32_64(brcond):
 621             if (swap_commutative(-1, &args[0], &args[1])) {
 622                 args[2] = tcg_swap_cond(args[2]);
 623             }
 624             break;
 625         CASE_OP_32_64(setcond):
 626             if (swap_commutative(args[0], &args[1], &args[2])) {
 627                 args[3] = tcg_swap_cond(args[3]);
 628             }
 629             break;
 630         CASE_OP_32_64(movcond):
 631             if (swap_commutative(-1, &args[1], &args[2])) {
 632                 args[5] = tcg_swap_cond(args[5]);
 633             }
 634             /* For movcond, we canonicalize the "false" input reg to match
 635                the destination reg so that the tcg backend can implement
 636                a "move if true" operation.  */
 637             if (swap_commutative(args[0], &args[4], &args[3])) {
 638                 args[5] = tcg_invert_cond(args[5]);
 639             }
 640             break;
 641         CASE_OP_32_64(add2):
 642             swap_commutative(args[0], &args[2], &args[4]);
 643             swap_commutative(args[1], &args[3], &args[5]);
 644             break;
 645         CASE_OP_32_64(mulu2):
 646         CASE_OP_32_64(muls2):
 647             swap_commutative(args[0], &args[2], &args[3]);
 648             break;
 649         case INDEX_op_brcond2_i32:
 650             if (swap_commutative2(&args[0], &args[2])) {
 651                 args[4] = tcg_swap_cond(args[4]);
 652             }
 653             break;
 654         case INDEX_op_setcond2_i32:
 655             if (swap_commutative2(&args[1], &args[3])) {
 656                 args[5] = tcg_swap_cond(args[5]);
 657             }
 658             break;
 659         default:
 660             break;
 661         }
 662
 663         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0",
 664            and "sub r, 0, a => neg r, a" case.  */
 665         switch (opc) {
 666         CASE_OP_32_64(shl):
 667         CASE_OP_32_64(shr):
 668         CASE_OP_32_64(sar):
 669         CASE_OP_32_64(rotl):
 670         CASE_OP_32_64(rotr):
 671             if (temps[args[1]].state == TCG_TEMP_CONST
 672                 && temps[args[1]].val == 0) {
 673                 tcg_opt_gen_movi(s, op, args, opc, args[0], 0);
 674                 continue;
 675             }
 676             break;
 677         CASE_OP_32_64(sub):
 678             {
 679                 TCGOpcode neg_op;
 680                 bool have_neg;
 681
 682                 if (temps[args[2]].state == TCG_TEMP_CONST) {
 683                     /* Proceed with possible constant folding. */
 684                     break;
 685                 }
 686                 if (opc == INDEX_op_sub_i32) {
 687                     neg_op = INDEX_op_neg_i32;
 688                     have_neg = TCG_TARGET_HAS_neg_i32;
 689                 } else {
 690                     neg_op = INDEX_op_neg_i64;
 691                     have_neg = TCG_TARGET_HAS_neg_i64;
 692                 }
 693                 if (!have_neg) {
 694                     break;
 695                 }
 696                 if (temps[args[1]].state == TCG_TEMP_CONST
 697                     && temps[args[1]].val == 0) {
 698                     op->opc = neg_op;
 699                     reset_temp(args[0]);
 700                     args[1] = args[2];
 701                     continue;
 702                 }
 703             }
 704             break;
 705         CASE_OP_32_64(xor):
 706         CASE_OP_32_64(nand):
 707             if (temps[args[1]].state != TCG_TEMP_CONST
 708                 && temps[args[2]].state == TCG_TEMP_CONST
 709                 && temps[args[2]].val == -1) {
 710                 i = 1;
 711                 goto try_not;
 712             }
 713             break;
 714         CASE_OP_32_64(nor):
 715             if (temps[args[1]].state != TCG_TEMP_CONST
 716                 && temps[args[2]].state == TCG_TEMP_CONST
 717                 && temps[args[2]].val == 0) {
 718                 i = 1;
 719                 goto try_not;
 720             }
 721             break;
 722         CASE_OP_32_64(andc):
 723             if (temps[args[2]].state != TCG_TEMP_CONST
 724                 && temps[args[1]].state == TCG_TEMP_CONST
 725                 && temps[args[1]].val == -1) {
 726                 i = 2;
 727                 goto try_not;
 728             }
 729             break;
 730         CASE_OP_32_64(orc):
 731         CASE_OP_32_64(eqv):
 732             if (temps[args[2]].state != TCG_TEMP_CONST
 733                 && temps[args[1]].state == TCG_TEMP_CONST
 734                 && temps[args[1]].val == 0) {
 735                 i = 2;
 736                 goto try_not;
 737             }
 738             break;
 739         try_not:
 740             {
 741                 TCGOpcode not_op;
 742                 bool have_not;
 743
 744                 if (def->flags & TCG_OPF_64BIT) {
 745                     not_op = INDEX_op_not_i64;
 746                     have_not = TCG_TARGET_HAS_not_i64;
 747                 } else {
 748                     not_op = INDEX_op_not_i32;
 749                     have_not = TCG_TARGET_HAS_not_i32;
 750                 }
 751                 if (!have_not) {
 752                     break;
 753                 }
 754                 op->opc = not_op;
 755                 reset_temp(args[0]);
 756                 args[1] = args[i];
 757                 continue;
 758             }
 759         default:
 760             break;
 761         }
 762
 763         /* Simplify expression for "op r, a, const => mov r, a" cases */
 764         switch (opc) {
 765         CASE_OP_32_64(add):
 766         CASE_OP_32_64(sub):
 767         CASE_OP_32_64(shl):
 768         CASE_OP_32_64(shr):
 769         CASE_OP_32_64(sar):
 770         CASE_OP_32_64(rotl):
 771         CASE_OP_32_64(rotr):
 772         CASE_OP_32_64(or):
 773         CASE_OP_32_64(xor):
 774         CASE_OP_32_64(andc):
 775             if (temps[args[1]].state != TCG_TEMP_CONST
 776                 && temps[args[2]].state == TCG_TEMP_CONST
 777                 && temps[args[2]].val == 0) {
 778                 goto do_mov3;
 779             }
 780             break;
 781         CASE_OP_32_64(and):
 782         CASE_OP_32_64(orc):
 783         CASE_OP_32_64(eqv):
 784             if (temps[args[1]].state != TCG_TEMP_CONST
 785                 && temps[args[2]].state == TCG_TEMP_CONST
 786                 && temps[args[2]].val == -1) {
 787                 goto do_mov3;
 788             }
 789             break;
 790         do_mov3:
 791             if (temps_are_copies(args[0], args[1])) {
 792                 tcg_op_remove(s, op);
 793             } else {
 794                 tcg_opt_gen_mov(s, op, args, opc, args[0], args[1]);
 795             }
 796             continue;
 797         default:
 798             break;
 799         }
 800
 801         /* Simplify using known-zero bits. Currently only ops with a single
 802            output argument is supported. */
 803         mask = -1;
 804         affected = -1;
 805         switch (opc) {
 806         CASE_OP_32_64(ext8s):
 807             if ((temps[args[1]].mask & 0x80) != 0) {
 808                 break;
 809             }
 810         CASE_OP_32_64(ext8u):
 811             mask = 0xff;
 812             goto and_const;
 813         CASE_OP_32_64(ext16s):
 814             if ((temps[args[1]].mask & 0x8000) != 0) {
 815                 break;
 816             }
 817         CASE_OP_32_64(ext16u):
 818             mask = 0xffff;
 819             goto and_const;
 820         case INDEX_op_ext32s_i64:
 821             if ((temps[args[1]].mask & 0x80000000) != 0) {
 822                 break;
 823             }
 824         case INDEX_op_ext32u_i64:
 825             mask = 0xffffffffU;
 826             goto and_const;
 827
 828         CASE_OP_32_64(and):
 829             mask = temps[args[2]].mask;
 830             if (temps[args[2]].state == TCG_TEMP_CONST) {
 831         and_const:
 832                 affected = temps[args[1]].mask & ~mask;
 833             }
 834             mask = temps[args[1]].mask & mask;
 835             break;
 836
 837         CASE_OP_32_64(andc):
 838             /* Known-zeros does not imply known-ones.  Therefore unless
 839                args[2] is constant, we can't infer anything from it.  */
 840             if (temps[args[2]].state == TCG_TEMP_CONST) {
 841                 mask = ~temps[args[2]].mask;
 842                 goto and_const;
 843             }
 844             /* But we certainly know nothing outside args[1] may be set. */
 845             mask = temps[args[1]].mask;
 846             break;
 847
 848         case INDEX_op_sar_i32:
 849             if (temps[args[2]].state == TCG_TEMP_CONST) {
 850                 tmp = temps[args[2]].val & 31;
 851                 mask = (int32_t)temps[args[1]].mask >> tmp;
 852             }
 853             break;
 854         case INDEX_op_sar_i64:
 855             if (temps[args[2]].state == TCG_TEMP_CONST) {
 856                 tmp = temps[args[2]].val & 63;
 857                 mask = (int64_t)temps[args[1]].mask >> tmp;
 858             }
 859             break;
 860
 861         case INDEX_op_shr_i32:
 862             if (temps[args[2]].state == TCG_TEMP_CONST) {
 863                 tmp = temps[args[2]].val & 31;
 864                 mask = (uint32_t)temps[args[1]].mask >> tmp;
 865             }
 866             break;
 867         case INDEX_op_shr_i64:
 868             if (temps[args[2]].state == TCG_TEMP_CONST) {
 869                 tmp = temps[args[2]].val & 63;
 870                 mask = (uint64_t)temps[args[1]].mask >> tmp;
 871             }
 872             break;
 873
 874         case INDEX_op_trunc_shr_i32:
 875             mask = (uint64_t)temps[args[1]].mask >> args[2];
 876             break;
 877
 878         CASE_OP_32_64(shl):
 879             if (temps[args[2]].state == TCG_TEMP_CONST) {
 880                 tmp = temps[args[2]].val & (TCG_TARGET_REG_BITS - 1);
 881                 mask = temps[args[1]].mask << tmp;
 882             }
 883             break;
 884
 885         CASE_OP_32_64(neg):
 886             /* Set to 1 all bits to the left of the rightmost.  */
 887             mask = -(temps[args[1]].mask & -temps[args[1]].mask);
 888             break;
 889
 890         CASE_OP_32_64(deposit):
 891             mask = deposit64(temps[args[1]].mask, args[3], args[4],
 892                              temps[args[2]].mask);
 893             break;
 894
 895         CASE_OP_32_64(or):
 896         CASE_OP_32_64(xor):
 897             mask = temps[args[1]].mask | temps[args[2]].mask;
 898             break;
 899
 900         CASE_OP_32_64(setcond):
 901         case INDEX_op_setcond2_i32:
 902             mask = 1;
 903             break;
 904
 905         CASE_OP_32_64(movcond):
 906             mask = temps[args[3]].mask | temps[args[4]].mask;
 907             break;
 908
 909         CASE_OP_32_64(ld8u):
 910             mask = 0xff;
 911             break;
 912         CASE_OP_32_64(ld16u):
 913             mask = 0xffff;
 914             break;
 915         case INDEX_op_ld32u_i64:
 916             mask = 0xffffffffu;
 917             break;
 918
 919         CASE_OP_32_64(qemu_ld):
 920             {
 921                 TCGMemOp mop = args[nb_oargs + nb_iargs];
 922                 if (!(mop & MO_SIGN)) {
 923                     mask = (2ULL << ((8 << (mop & MO_SIZE)) - 1)) - 1;
 924                 }
 925             }
 926             break;
 927
 928         default:
 929             break;
 930         }
 931
 932         /* 32-bit ops generate 32-bit results.  For the result is zero test
 933            below, we can ignore high bits, but for further optimizations we
 934            need to record that the high bits contain garbage.  */
 935         partmask = mask;
 936         if (!(def->flags & TCG_OPF_64BIT)) {
 937             mask |= ~(tcg_target_ulong)0xffffffffu;
 938             partmask &= 0xffffffffu;
 939             affected &= 0xffffffffu;
 940         }
 941
 942         if (partmask == 0) {
 943             assert(nb_oargs == 1);
 944             tcg_opt_gen_movi(s, op, args, opc, args[0], 0);
 945             continue;
 946         }
 947         if (affected == 0) {
 948             assert(nb_oargs == 1);
 949             if (temps_are_copies(args[0], args[1])) {
 950                 tcg_op_remove(s, op);
 951             } else if (temps[args[1]].state != TCG_TEMP_CONST) {
 952                 tcg_opt_gen_mov(s, op, args, opc, args[0], args[1]);
 953             } else {
 954                 tcg_opt_gen_movi(s, op, args, opc,
 955                                  args[0], temps[args[1]].val);
 956             }
 957             continue;
 958         }
 959
 960         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 961         switch (opc) {
 962         CASE_OP_32_64(and):
 963         CASE_OP_32_64(mul):
 964         CASE_OP_32_64(muluh):
 965         CASE_OP_32_64(mulsh):
 966             if ((temps[args[2]].state == TCG_TEMP_CONST
 967                 && temps[args[2]].val == 0)) {
 968                 tcg_opt_gen_movi(s, op, args, opc, args[0], 0);
 969                 continue;
 970             }
 971             break;
 972         default:
 973             break;
 974         }
 975
 976         /* Simplify expression for "op r, a, a => mov r, a" cases */
 977         switch (opc) {
 978         CASE_OP_32_64(or):
 979         CASE_OP_32_64(and):
 980             if (temps_are_copies(args[1], args[2])) {
 981                 if (temps_are_copies(args[0], args[1])) {
 982                     tcg_op_remove(s, op);
 983                 } else {
 984                     tcg_opt_gen_mov(s, op, args, opc, args[0], args[1]);
 985                 }
 986                 continue;
 987             }
 988             break;
 989         default:
 990             break;
 991         }
 992
 993         /* Simplify expression for "op r, a, a => movi r, 0" cases */
 994         switch (opc) {
 995         CASE_OP_32_64(andc):
 996         CASE_OP_32_64(sub):
 997         CASE_OP_32_64(xor):
 998             if (temps_are_copies(args[1], args[2])) {
 999                 tcg_opt_gen_movi(s, op, args, opc, args[0], 0);
1000                 continue;
1001             }
1002             break;
1003         default:
1004             break;
1005         }
1006
1007         /* Propagate constants through copy operations and do constant
1008            folding.  Constants will be substituted to arguments by register
1009            allocator where needed and possible.  Also detect copies. */
1010         switch (opc) {
1011         CASE_OP_32_64(mov):
1012             if (temps_are_copies(args[0], args[1])) {
1013                 tcg_op_remove(s, op);
1014                 break;
1015             }
1016             if (temps[args[1]].state != TCG_TEMP_CONST) {
1017                 tcg_opt_gen_mov(s, op, args, opc, args[0], args[1]);
1018                 break;
1019             }
1020             /* Source argument is constant.  Rewrite the operation and
1021                let movi case handle it. */
1022             args[1] = temps[args[1]].val;
1023             /* fallthrough */
1024         CASE_OP_32_64(movi):
1025             tcg_opt_gen_movi(s, op, args, opc, args[0], args[1]);
1026             break;
1027
1028         CASE_OP_32_64(not):
1029         CASE_OP_32_64(neg):
1030         CASE_OP_32_64(ext8s):
1031         CASE_OP_32_64(ext8u):
1032         CASE_OP_32_64(ext16s):
1033         CASE_OP_32_64(ext16u):
1034         case INDEX_op_ext32s_i64:
1035         case INDEX_op_ext32u_i64:
1036             if (temps[args[1]].state == TCG_TEMP_CONST) {
1037                 tmp = do_constant_folding(opc, temps[args[1]].val, 0);
1038                 tcg_opt_gen_movi(s, op, args, opc, args[0], tmp);
1039                 break;
1040             }
1041             goto do_default;
1042
1043         case INDEX_op_trunc_shr_i32:
1044             if (temps[args[1]].state == TCG_TEMP_CONST) {
1045                 tmp = do_constant_folding(opc, temps[args[1]].val, args[2]);
1046                 tcg_opt_gen_movi(s, op, args, opc, args[0], tmp);
1047                 break;
1048             }
1049             goto do_default;
1050
1051         CASE_OP_32_64(add):
1052         CASE_OP_32_64(sub):
1053         CASE_OP_32_64(mul):
1054         CASE_OP_32_64(or):
1055         CASE_OP_32_64(and):
1056         CASE_OP_32_64(xor):
1057         CASE_OP_32_64(shl):
1058         CASE_OP_32_64(shr):
1059         CASE_OP_32_64(sar):
1060         CASE_OP_32_64(rotl):
1061         CASE_OP_32_64(rotr):
1062         CASE_OP_32_64(andc):
1063         CASE_OP_32_64(orc):
1064         CASE_OP_32_64(eqv):
1065         CASE_OP_32_64(nand):
1066         CASE_OP_32_64(nor):
1067         CASE_OP_32_64(muluh):
1068         CASE_OP_32_64(mulsh):
1069         CASE_OP_32_64(div):
1070         CASE_OP_32_64(divu):
1071         CASE_OP_32_64(rem):
1072         CASE_OP_32_64(remu):
1073             if (temps[args[1]].state == TCG_TEMP_CONST
1074                 && temps[args[2]].state == TCG_TEMP_CONST) {
1075                 tmp = do_constant_folding(opc, temps[args[1]].val,
1076                                           temps[args[2]].val);
1077                 tcg_opt_gen_movi(s, op, args, opc, args[0], tmp);
1078                 break;
1079             }
1080             goto do_default;
1081
1082         CASE_OP_32_64(deposit):
1083             if (temps[args[1]].state == TCG_TEMP_CONST
1084                 && temps[args[2]].state == TCG_TEMP_CONST) {
1085                 tmp = deposit64(temps[args[1]].val, args[3], args[4],
1086                                 temps[args[2]].val);
1087                 tcg_opt_gen_movi(s, op, args, opc, args[0], tmp);
1088                 break;
1089             }
1090             goto do_default;
1091
1092         CASE_OP_32_64(setcond):
1093             tmp = do_constant_folding_cond(opc, args[1], args[2], args[3]);
1094             if (tmp != 2) {
1095                 tcg_opt_gen_movi(s, op, args, opc, args[0], tmp);
1096                 break;
1097             }
1098             goto do_default;
1099
1100         CASE_OP_32_64(brcond):
1101             tmp = do_constant_folding_cond(opc, args[0], args[1], args[2]);
1102             if (tmp != 2) {
1103                 if (tmp) {
1104                     reset_all_temps(nb_temps);
1105                     op->opc = INDEX_op_br;
1106                     args[0] = args[3];
1107                 } else {
1108                     tcg_op_remove(s, op);
1109                 }
1110                 break;
1111             }
1112             goto do_default;
1113
1114         CASE_OP_32_64(movcond):
1115             tmp = do_constant_folding_cond(opc, args[1], args[2], args[5]);
1116             if (tmp != 2) {
1117                 if (temps_are_copies(args[0], args[4-tmp])) {
1118                     tcg_op_remove(s, op);
1119                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
1120                     tcg_opt_gen_movi(s, op, args, opc,
1121                                      args[0], temps[args[4-tmp]].val);
1122                 } else {
1123                     tcg_opt_gen_mov(s, op, args, opc, args[0], args[4-tmp]);
1124                 }
1125                 break;
1126             }
1127             goto do_default;
1128
1129         case INDEX_op_add2_i32:
1130         case INDEX_op_sub2_i32:
1131             if (temps[args[2]].state == TCG_TEMP_CONST
1132                 && temps[args[3]].state == TCG_TEMP_CONST
1133                 && temps[args[4]].state == TCG_TEMP_CONST
1134                 && temps[args[5]].state == TCG_TEMP_CONST) {
1135                 uint32_t al = temps[args[2]].val;
1136                 uint32_t ah = temps[args[3]].val;
1137                 uint32_t bl = temps[args[4]].val;
1138                 uint32_t bh = temps[args[5]].val;
1139                 uint64_t a = ((uint64_t)ah << 32) | al;
1140                 uint64_t b = ((uint64_t)bh << 32) | bl;
1141                 TCGArg rl, rh;
1142                 TCGOp *op2 = insert_op_before(s, op, INDEX_op_movi_i32, 2);
1143                 TCGArg *args2 = &s->gen_opparam_buf[op2->args];
1144
1145                 if (opc == INDEX_op_add2_i32) {
1146                     a += b;
1147                 } else {
1148                     a -= b;
1149                 }
1150
1151                 rl = args[0];
1152                 rh = args[1];
1153                 tcg_opt_gen_movi(s, op, args, opc, rl, (uint32_t)a);
1154                 tcg_opt_gen_movi(s, op2, args2, opc, rh, (uint32_t)(a >> 32));
1155
1156                 /* We've done all we need to do with the movi.  Skip it.  */
1157                 oi_next = op2->next;
1158                 break;
1159             }
1160             goto do_default;
1161
1162         case INDEX_op_mulu2_i32:
1163             if (temps[args[2]].state == TCG_TEMP_CONST
1164                 && temps[args[3]].state == TCG_TEMP_CONST) {
1165                 uint32_t a = temps[args[2]].val;
1166                 uint32_t b = temps[args[3]].val;
1167                 uint64_t r = (uint64_t)a * b;
1168                 TCGArg rl, rh;
1169                 TCGOp *op2 = insert_op_before(s, op, INDEX_op_movi_i32, 2);
1170                 TCGArg *args2 = &s->gen_opparam_buf[op2->args];
1171
1172                 rl = args[0];
1173                 rh = args[1];
1174                 tcg_opt_gen_movi(s, op, args, opc, rl, (uint32_t)r);
1175                 tcg_opt_gen_movi(s, op2, args2, opc, rh, (uint32_t)(r >> 32));
1176
1177                 /* We've done all we need to do with the movi.  Skip it.  */
1178                 oi_next = op2->next;
1179                 break;
1180             }
1181             goto do_default;
1182
1183         case INDEX_op_brcond2_i32:
1184             tmp = do_constant_folding_cond2(&args[0], &args[2], args[4]);
1185             if (tmp != 2) {
1186                 if (tmp) {
1187             do_brcond_true:
1188                     reset_all_temps(nb_temps);
1189                     op->opc = INDEX_op_br;
1190                     args[0] = args[5];
1191                 } else {
1192             do_brcond_false:
1193                     tcg_op_remove(s, op);
1194                 }
1195             } else if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
1196                        && temps[args[2]].state == TCG_TEMP_CONST
1197                        && temps[args[3]].state == TCG_TEMP_CONST
1198                        && temps[args[2]].val == 0
1199                        && temps[args[3]].val == 0) {
1200                 /* Simplify LT/GE comparisons vs zero to a single compare
1201                    vs the high word of the input.  */
1202             do_brcond_high:
1203                 reset_all_temps(nb_temps);
1204                 op->opc = INDEX_op_brcond_i32;
1205                 args[0] = args[1];
1206                 args[1] = args[3];
1207                 args[2] = args[4];
1208                 args[3] = args[5];
1209             } else if (args[4] == TCG_COND_EQ) {
1210                 /* Simplify EQ comparisons where one of the pairs
1211                    can be simplified.  */
1212                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1213                                                args[0], args[2], TCG_COND_EQ);
1214                 if (tmp == 0) {
1215                     goto do_brcond_false;
1216                 } else if (tmp == 1) {
1217                     goto do_brcond_high;
1218                 }
1219                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1220                                                args[1], args[3], TCG_COND_EQ);
1221                 if (tmp == 0) {
1222                     goto do_brcond_false;
1223                 } else if (tmp != 1) {
1224                     goto do_default;
1225                 }
1226             do_brcond_low:
1227                 reset_all_temps(nb_temps);
1228                 op->opc = INDEX_op_brcond_i32;
1229                 args[1] = args[2];
1230                 args[2] = args[4];
1231                 args[3] = args[5];
1232             } else if (args[4] == TCG_COND_NE) {
1233                 /* Simplify NE comparisons where one of the pairs
1234                    can be simplified.  */
1235                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1236                                                args[0], args[2], TCG_COND_NE);
1237                 if (tmp == 0) {
1238                     goto do_brcond_high;
1239                 } else if (tmp == 1) {
1240                     goto do_brcond_true;
1241                 }
1242                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1243                                                args[1], args[3], TCG_COND_NE);
1244                 if (tmp == 0) {
1245                     goto do_brcond_low;
1246                 } else if (tmp == 1) {
1247                     goto do_brcond_true;
1248                 }
1249                 goto do_default;
1250             } else {
1251                 goto do_default;
1252             }
1253             break;
1254
1255         case INDEX_op_setcond2_i32:
1256             tmp = do_constant_folding_cond2(&args[1], &args[3], args[5]);
1257             if (tmp != 2) {
1258             do_setcond_const:
1259                 tcg_opt_gen_movi(s, op, args, opc, args[0], tmp);
1260             } else if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
1261                        && temps[args[3]].state == TCG_TEMP_CONST
1262                        && temps[args[4]].state == TCG_TEMP_CONST
1263                        && temps[args[3]].val == 0
1264                        && temps[args[4]].val == 0) {
1265                 /* Simplify LT/GE comparisons vs zero to a single compare
1266                    vs the high word of the input.  */
1267             do_setcond_high:
1268                 reset_temp(args[0]);
1269                 temps[args[0]].mask = 1;
1270                 op->opc = INDEX_op_setcond_i32;
1271                 args[1] = args[2];
1272                 args[2] = args[4];
1273                 args[3] = args[5];
1274             } else if (args[5] == TCG_COND_EQ) {
1275                 /* Simplify EQ comparisons where one of the pairs
1276                    can be simplified.  */
1277                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1278                                                args[1], args[3], TCG_COND_EQ);
1279                 if (tmp == 0) {
1280                     goto do_setcond_const;
1281                 } else if (tmp == 1) {
1282                     goto do_setcond_high;
1283                 }
1284                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1285                                                args[2], args[4], TCG_COND_EQ);
1286                 if (tmp == 0) {
1287                     goto do_setcond_high;
1288                 } else if (tmp != 1) {
1289                     goto do_default;
1290                 }
1291             do_setcond_low:
1292                 reset_temp(args[0]);
1293                 temps[args[0]].mask = 1;
1294                 op->opc = INDEX_op_setcond_i32;
1295                 args[2] = args[3];
1296                 args[3] = args[5];
1297             } else if (args[5] == TCG_COND_NE) {
1298                 /* Simplify NE comparisons where one of the pairs
1299                    can be simplified.  */
1300                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1301                                                args[1], args[3], TCG_COND_NE);
1302                 if (tmp == 0) {
1303                     goto do_setcond_high;
1304                 } else if (tmp == 1) {
1305                     goto do_setcond_const;
1306                 }
1307                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1308                                                args[2], args[4], TCG_COND_NE);
1309                 if (tmp == 0) {
1310                     goto do_setcond_low;
1311                 } else if (tmp == 1) {
1312                     goto do_setcond_const;
1313                 }
1314                 goto do_default;
1315             } else {
1316                 goto do_default;
1317             }
1318             break;
1319
1320         case INDEX_op_call:
1321             if (!(args[nb_oargs + nb_iargs + 1]
1322                   & (TCG_CALL_NO_READ_GLOBALS | TCG_CALL_NO_WRITE_GLOBALS))) {
1323                 for (i = 0; i < nb_globals; i++) {
1324                     reset_temp(i);
1325                 }
1326             }
1327             goto do_reset_output;
1328
1329         default:
1330         do_default:
1331             /* Default case: we know nothing about operation (or were unable
1332                to compute the operation result) so no propagation is done.
1333                We trash everything if the operation is the end of a basic
1334                block, otherwise we only trash the output args.  "mask" is
1335                the non-zero bits mask for the first output arg.  */
1336             if (def->flags & TCG_OPF_BB_END) {
1337                 reset_all_temps(nb_temps);
1338             } else {
1339         do_reset_output:
1340                 for (i = 0; i < nb_oargs; i++) {
1341                     reset_temp(args[i]);
1342                     /* Save the corresponding known-zero bits mask for the
1343                        first output argument (only one supported so far). */
1344                     if (i == 0) {
1345                         temps[args[i]].mask = mask;
1346                     }
1347                 }
1348             }
1349             break;
1350         }
1351     }
1352 }
1353
1354 void tcg_optimize(TCGContext *s)
1355 {
1356     tcg_constant_folding(s);
1357 }