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