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 /* Reset all temporaries, given that there are NB_TEMPS of them.  */
  71 static void reset_all_temps(int nb_temps)
  72 {
  73     int i;
  74     for (i = 0; i < nb_temps; i++) {
  75         temps[i].state = TCG_TEMP_UNDEF;
  76         temps[i].mask = -1;
  77     }
  78 }
  79
  80 static int op_bits(TCGOpcode op)
  81 {
  82     const TCGOpDef *def = &tcg_op_defs[op];
  83     return def->flags & TCG_OPF_64BIT ? 64 : 32;
  84 }
  85
  86 static TCGOpcode op_to_mov(TCGOpcode op)
  87 {
  88     switch (op_bits(op)) {
  89     case 32:
  90         return INDEX_op_mov_i32;
  91     case 64:
  92         return INDEX_op_mov_i64;
  93     default:
  94         fprintf(stderr, "op_to_mov: unexpected return value of "
  95                 "function op_bits.\n");
  96         tcg_abort();
  97     }
  98 }
  99
 100 static TCGOpcode op_to_movi(TCGOpcode op)
 101 {
 102     switch (op_bits(op)) {
 103     case 32:
 104         return INDEX_op_movi_i32;
 105     case 64:
 106         return INDEX_op_movi_i64;
 107     default:
 108         fprintf(stderr, "op_to_movi: unexpected return value of "
 109                 "function op_bits.\n");
 110         tcg_abort();
 111     }
 112 }
 113
 114 static TCGArg find_better_copy(TCGContext *s, TCGArg temp)
 115 {
 116     TCGArg i;
 117
 118     /* If this is already a global, we can't do better. */
 119     if (temp < s->nb_globals) {
 120         return temp;
 121     }
 122
 123     /* Search for a global first. */
 124     for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
 125         if (i < s->nb_globals) {
 126             return i;
 127         }
 128     }
 129
 130     /* If it is a temp, search for a temp local. */
 131     if (!s->temps[temp].temp_local) {
 132         for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
 133             if (s->temps[i].temp_local) {
 134                 return i;
 135             }
 136         }
 137     }
 138
 139     /* Failure to find a better representation, return the same temp. */
 140     return temp;
 141 }
 142
 143 static bool temps_are_copies(TCGArg arg1, TCGArg arg2)
 144 {
 145     TCGArg i;
 146
 147     if (arg1 == arg2) {
 148         return true;
 149     }
 150
 151     if (temps[arg1].state != TCG_TEMP_COPY
 152         || temps[arg2].state != TCG_TEMP_COPY) {
 153         return false;
 154     }
 155
 156     for (i = temps[arg1].next_copy ; i != arg1 ; i = temps[i].next_copy) {
 157         if (i == arg2) {
 158             return true;
 159         }
 160     }
 161
 162     return false;
 163 }
 164
 165 static void tcg_opt_gen_mov(TCGContext *s, int op_index, TCGArg *gen_args,
 166                             TCGOpcode old_op, TCGArg dst, TCGArg src)
 167 {
 168     TCGOpcode new_op = op_to_mov(old_op);
 169     tcg_target_ulong mask;
 170
 171     s->gen_opc_buf[op_index] = new_op;
 172
 173     reset_temp(dst);
 174     mask = temps[src].mask;
 175     if (TCG_TARGET_REG_BITS > 32 && new_op == INDEX_op_mov_i32) {
 176         /* High bits of the destination are now garbage.  */
 177         mask |= ~0xffffffffull;
 178     }
 179     temps[dst].mask = mask;
 180
 181     assert(temps[src].state != TCG_TEMP_CONST);
 182
 183     if (s->temps[src].type == s->temps[dst].type) {
 184         if (temps[src].state != TCG_TEMP_COPY) {
 185             temps[src].state = TCG_TEMP_COPY;
 186             temps[src].next_copy = src;
 187             temps[src].prev_copy = src;
 188         }
 189         temps[dst].state = TCG_TEMP_COPY;
 190         temps[dst].next_copy = temps[src].next_copy;
 191         temps[dst].prev_copy = src;
 192         temps[temps[dst].next_copy].prev_copy = dst;
 193         temps[src].next_copy = dst;
 194     }
 195
 196     gen_args[0] = dst;
 197     gen_args[1] = src;
 198 }
 199
 200 static void tcg_opt_gen_movi(TCGContext *s, int op_index, TCGArg *gen_args,
 201                              TCGOpcode old_op, TCGArg dst, TCGArg val)
 202 {
 203     TCGOpcode new_op = op_to_movi(old_op);
 204     tcg_target_ulong mask;
 205
 206     s->gen_opc_buf[op_index] = new_op;
 207
 208     reset_temp(dst);
 209     temps[dst].state = TCG_TEMP_CONST;
 210     temps[dst].val = val;
 211     mask = val;
 212     if (TCG_TARGET_REG_BITS > 32 && new_op == INDEX_op_mov_i32) {
 213         /* High bits of the destination are now garbage.  */
 214         mask |= ~0xffffffffull;
 215     }
 216     temps[dst].mask = mask;
 217
 218     gen_args[0] = dst;
 219     gen_args[1] = val;
 220 }
 221
 222 static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
 223 {
 224     uint64_t l64, h64;
 225
 226     switch (op) {
 227     CASE_OP_32_64(add):
 228         return x + y;
 229
 230     CASE_OP_32_64(sub):
 231         return x - y;
 232
 233     CASE_OP_32_64(mul):
 234         return x * y;
 235
 236     CASE_OP_32_64(and):
 237         return x & y;
 238
 239     CASE_OP_32_64(or):
 240         return x | y;
 241
 242     CASE_OP_32_64(xor):
 243         return x ^ y;
 244
 245     case INDEX_op_shl_i32:
 246         return (uint32_t)x << (y & 31);
 247
 248     case INDEX_op_shl_i64:
 249         return (uint64_t)x << (y & 63);
 250
 251     case INDEX_op_shr_i32:
 252         return (uint32_t)x >> (y & 31);
 253
 254     case INDEX_op_trunc_shr_i32:
 255     case INDEX_op_shr_i64:
 256         return (uint64_t)x >> (y & 63);
 257
 258     case INDEX_op_sar_i32:
 259         return (int32_t)x >> (y & 31);
 260
 261     case INDEX_op_sar_i64:
 262         return (int64_t)x >> (y & 63);
 263
 264     case INDEX_op_rotr_i32:
 265         return ror32(x, y & 31);
 266
 267     case INDEX_op_rotr_i64:
 268         return ror64(x, y & 63);
 269
 270     case INDEX_op_rotl_i32:
 271         return rol32(x, y & 31);
 272
 273     case INDEX_op_rotl_i64:
 274         return rol64(x, y & 63);
 275
 276     CASE_OP_32_64(not):
 277         return ~x;
 278
 279     CASE_OP_32_64(neg):
 280         return -x;
 281
 282     CASE_OP_32_64(andc):
 283         return x & ~y;
 284
 285     CASE_OP_32_64(orc):
 286         return x | ~y;
 287
 288     CASE_OP_32_64(eqv):
 289         return ~(x ^ y);
 290
 291     CASE_OP_32_64(nand):
 292         return ~(x & y);
 293
 294     CASE_OP_32_64(nor):
 295         return ~(x | y);
 296
 297     CASE_OP_32_64(ext8s):
 298         return (int8_t)x;
 299
 300     CASE_OP_32_64(ext16s):
 301         return (int16_t)x;
 302
 303     CASE_OP_32_64(ext8u):
 304         return (uint8_t)x;
 305
 306     CASE_OP_32_64(ext16u):
 307         return (uint16_t)x;
 308
 309     case INDEX_op_ext32s_i64:
 310         return (int32_t)x;
 311
 312     case INDEX_op_ext32u_i64:
 313         return (uint32_t)x;
 314
 315     case INDEX_op_muluh_i32:
 316         return ((uint64_t)(uint32_t)x * (uint32_t)y) >> 32;
 317     case INDEX_op_mulsh_i32:
 318         return ((int64_t)(int32_t)x * (int32_t)y) >> 32;
 319
 320     case INDEX_op_muluh_i64:
 321         mulu64(&l64, &h64, x, y);
 322         return h64;
 323     case INDEX_op_mulsh_i64:
 324         muls64(&l64, &h64, x, y);
 325         return h64;
 326
 327     case INDEX_op_div_i32:
 328         /* Avoid crashing on divide by zero, otherwise undefined.  */
 329         return (int32_t)x / ((int32_t)y ? : 1);
 330     case INDEX_op_divu_i32:
 331         return (uint32_t)x / ((uint32_t)y ? : 1);
 332     case INDEX_op_div_i64:
 333         return (int64_t)x / ((int64_t)y ? : 1);
 334     case INDEX_op_divu_i64:
 335         return (uint64_t)x / ((uint64_t)y ? : 1);
 336
 337     case INDEX_op_rem_i32:
 338         return (int32_t)x % ((int32_t)y ? : 1);
 339     case INDEX_op_remu_i32:
 340         return (uint32_t)x % ((uint32_t)y ? : 1);
 341     case INDEX_op_rem_i64:
 342         return (int64_t)x % ((int64_t)y ? : 1);
 343     case INDEX_op_remu_i64:
 344         return (uint64_t)x % ((uint64_t)y ? : 1);
 345
 346     default:
 347         fprintf(stderr,
 348                 "Unrecognized operation %d in do_constant_folding.\n", op);
 349         tcg_abort();
 350     }
 351 }
 352
 353 static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
 354 {
 355     TCGArg res = do_constant_folding_2(op, x, y);
 356     if (op_bits(op) == 32) {
 357         res &= 0xffffffff;
 358     }
 359     return res;
 360 }
 361
 362 static bool do_constant_folding_cond_32(uint32_t x, uint32_t y, TCGCond c)
 363 {
 364     switch (c) {
 365     case TCG_COND_EQ:
 366         return x == y;
 367     case TCG_COND_NE:
 368         return x != y;
 369     case TCG_COND_LT:
 370         return (int32_t)x < (int32_t)y;
 371     case TCG_COND_GE:
 372         return (int32_t)x >= (int32_t)y;
 373     case TCG_COND_LE:
 374         return (int32_t)x <= (int32_t)y;
 375     case TCG_COND_GT:
 376         return (int32_t)x > (int32_t)y;
 377     case TCG_COND_LTU:
 378         return x < y;
 379     case TCG_COND_GEU:
 380         return x >= y;
 381     case TCG_COND_LEU:
 382         return x <= y;
 383     case TCG_COND_GTU:
 384         return x > y;
 385     default:
 386         tcg_abort();
 387     }
 388 }
 389
 390 static bool do_constant_folding_cond_64(uint64_t x, uint64_t y, TCGCond c)
 391 {
 392     switch (c) {
 393     case TCG_COND_EQ:
 394         return x == y;
 395     case TCG_COND_NE:
 396         return x != y;
 397     case TCG_COND_LT:
 398         return (int64_t)x < (int64_t)y;
 399     case TCG_COND_GE:
 400         return (int64_t)x >= (int64_t)y;
 401     case TCG_COND_LE:
 402         return (int64_t)x <= (int64_t)y;
 403     case TCG_COND_GT:
 404         return (int64_t)x > (int64_t)y;
 405     case TCG_COND_LTU:
 406         return x < y;
 407     case TCG_COND_GEU:
 408         return x >= y;
 409     case TCG_COND_LEU:
 410         return x <= y;
 411     case TCG_COND_GTU:
 412         return x > y;
 413     default:
 414         tcg_abort();
 415     }
 416 }
 417
 418 static bool do_constant_folding_cond_eq(TCGCond c)
 419 {
 420     switch (c) {
 421     case TCG_COND_GT:
 422     case TCG_COND_LTU:
 423     case TCG_COND_LT:
 424     case TCG_COND_GTU:
 425     case TCG_COND_NE:
 426         return 0;
 427     case TCG_COND_GE:
 428     case TCG_COND_GEU:
 429     case TCG_COND_LE:
 430     case TCG_COND_LEU:
 431     case TCG_COND_EQ:
 432         return 1;
 433     default:
 434         tcg_abort();
 435     }
 436 }
 437
 438 /* Return 2 if the condition can't be simplified, and the result
 439    of the condition (0 or 1) if it can */
 440 static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
 441                                        TCGArg y, TCGCond c)
 442 {
 443     if (temps[x].state == TCG_TEMP_CONST && temps[y].state == TCG_TEMP_CONST) {
 444         switch (op_bits(op)) {
 445         case 32:
 446             return do_constant_folding_cond_32(temps[x].val, temps[y].val, c);
 447         case 64:
 448             return do_constant_folding_cond_64(temps[x].val, temps[y].val, c);
 449         default:
 450             tcg_abort();
 451         }
 452     } else if (temps_are_copies(x, y)) {
 453         return do_constant_folding_cond_eq(c);
 454     } else if (temps[y].state == TCG_TEMP_CONST && temps[y].val == 0) {
 455         switch (c) {
 456         case TCG_COND_LTU:
 457             return 0;
 458         case TCG_COND_GEU:
 459             return 1;
 460         default:
 461             return 2;
 462         }
 463     } else {
 464         return 2;
 465     }
 466 }
 467
 468 /* Return 2 if the condition can't be simplified, and the result
 469    of the condition (0 or 1) if it can */
 470 static TCGArg do_constant_folding_cond2(TCGArg *p1, TCGArg *p2, TCGCond c)
 471 {
 472     TCGArg al = p1[0], ah = p1[1];
 473     TCGArg bl = p2[0], bh = p2[1];
 474
 475     if (temps[bl].state == TCG_TEMP_CONST
 476         && temps[bh].state == TCG_TEMP_CONST) {
 477         uint64_t b = ((uint64_t)temps[bh].val << 32) | (uint32_t)temps[bl].val;
 478
 479         if (temps[al].state == TCG_TEMP_CONST
 480             && temps[ah].state == TCG_TEMP_CONST) {
 481             uint64_t a;
 482             a = ((uint64_t)temps[ah].val << 32) | (uint32_t)temps[al].val;
 483             return do_constant_folding_cond_64(a, b, c);
 484         }
 485         if (b == 0) {
 486             switch (c) {
 487             case TCG_COND_LTU:
 488                 return 0;
 489             case TCG_COND_GEU:
 490                 return 1;
 491             default:
 492                 break;
 493             }
 494         }
 495     }
 496     if (temps_are_copies(al, bl) && temps_are_copies(ah, bh)) {
 497         return do_constant_folding_cond_eq(c);
 498     }
 499     return 2;
 500 }
 501
 502 static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2)
 503 {
 504     TCGArg a1 = *p1, a2 = *p2;
 505     int sum = 0;
 506     sum += temps[a1].state == TCG_TEMP_CONST;
 507     sum -= temps[a2].state == TCG_TEMP_CONST;
 508
 509     /* Prefer the constant in second argument, and then the form
 510        op a, a, b, which is better handled on non-RISC hosts. */
 511     if (sum > 0 || (sum == 0 && dest == a2)) {
 512         *p1 = a2;
 513         *p2 = a1;
 514         return true;
 515     }
 516     return false;
 517 }
 518
 519 static bool swap_commutative2(TCGArg *p1, TCGArg *p2)
 520 {
 521     int sum = 0;
 522     sum += temps[p1[0]].state == TCG_TEMP_CONST;
 523     sum += temps[p1[1]].state == TCG_TEMP_CONST;
 524     sum -= temps[p2[0]].state == TCG_TEMP_CONST;
 525     sum -= temps[p2[1]].state == TCG_TEMP_CONST;
 526     if (sum > 0) {
 527         TCGArg t;
 528         t = p1[0], p1[0] = p2[0], p2[0] = t;
 529         t = p1[1], p1[1] = p2[1], p2[1] = t;
 530         return true;
 531     }
 532     return false;
 533 }
 534
 535 /* Propagate constants and copies, fold constant expressions. */
 536 static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
 537                                     TCGArg *args, TCGOpDef *tcg_op_defs)
 538 {
 539     int nb_ops, op_index, nb_temps, nb_globals;
 540     TCGArg *gen_args;
 541
 542     /* Array VALS has an element for each temp.
 543        If this temp holds a constant then its value is kept in VALS' element.
 544        If this temp is a copy of other ones then the other copies are
 545        available through the doubly linked circular list. */
 546
 547     nb_temps = s->nb_temps;
 548     nb_globals = s->nb_globals;
 549     reset_all_temps(nb_temps);
 550
 551     nb_ops = tcg_opc_ptr - s->gen_opc_buf;
 552     gen_args = args;
 553     for (op_index = 0; op_index < nb_ops; op_index++) {
 554         TCGOpcode op = s->gen_opc_buf[op_index];
 555         const TCGOpDef *def = &tcg_op_defs[op];
 556         tcg_target_ulong mask, partmask, affected;
 557         int nb_oargs, nb_iargs, nb_args, i;
 558         TCGArg tmp;
 559
 560         if (op == INDEX_op_call) {
 561             *gen_args++ = tmp = *args++;
 562             nb_oargs = tmp >> 16;
 563             nb_iargs = tmp & 0xffff;
 564             nb_args = nb_oargs + nb_iargs + def->nb_cargs;
 565         } else {
 566             nb_oargs = def->nb_oargs;
 567             nb_iargs = def->nb_iargs;
 568             nb_args = def->nb_args;
 569         }
 570
 571         /* Do copy propagation */
 572         for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
 573             if (temps[args[i]].state == TCG_TEMP_COPY) {
 574                 args[i] = find_better_copy(s, args[i]);
 575             }
 576         }
 577
 578         /* For commutative operations make constant second argument */
 579         switch (op) {
 580         CASE_OP_32_64(add):
 581         CASE_OP_32_64(mul):
 582         CASE_OP_32_64(and):
 583         CASE_OP_32_64(or):
 584         CASE_OP_32_64(xor):
 585         CASE_OP_32_64(eqv):
 586         CASE_OP_32_64(nand):
 587         CASE_OP_32_64(nor):
 588         CASE_OP_32_64(muluh):
 589         CASE_OP_32_64(mulsh):
 590             swap_commutative(args[0], &args[1], &args[2]);
 591             break;
 592         CASE_OP_32_64(brcond):
 593             if (swap_commutative(-1, &args[0], &args[1])) {
 594                 args[2] = tcg_swap_cond(args[2]);
 595             }
 596             break;
 597         CASE_OP_32_64(setcond):
 598             if (swap_commutative(args[0], &args[1], &args[2])) {
 599                 args[3] = tcg_swap_cond(args[3]);
 600             }
 601             break;
 602         CASE_OP_32_64(movcond):
 603             if (swap_commutative(-1, &args[1], &args[2])) {
 604                 args[5] = tcg_swap_cond(args[5]);
 605             }
 606             /* For movcond, we canonicalize the "false" input reg to match
 607                the destination reg so that the tcg backend can implement
 608                a "move if true" operation.  */
 609             if (swap_commutative(args[0], &args[4], &args[3])) {
 610                 args[5] = tcg_invert_cond(args[5]);
 611             }
 612             break;
 613         CASE_OP_32_64(add2):
 614             swap_commutative(args[0], &args[2], &args[4]);
 615             swap_commutative(args[1], &args[3], &args[5]);
 616             break;
 617         CASE_OP_32_64(mulu2):
 618         CASE_OP_32_64(muls2):
 619             swap_commutative(args[0], &args[2], &args[3]);
 620             break;
 621         case INDEX_op_brcond2_i32:
 622             if (swap_commutative2(&args[0], &args[2])) {
 623                 args[4] = tcg_swap_cond(args[4]);
 624             }
 625             break;
 626         case INDEX_op_setcond2_i32:
 627             if (swap_commutative2(&args[1], &args[3])) {
 628                 args[5] = tcg_swap_cond(args[5]);
 629             }
 630             break;
 631         default:
 632             break;
 633         }
 634
 635         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0",
 636            and "sub r, 0, a => neg r, a" case.  */
 637         switch (op) {
 638         CASE_OP_32_64(shl):
 639         CASE_OP_32_64(shr):
 640         CASE_OP_32_64(sar):
 641         CASE_OP_32_64(rotl):
 642         CASE_OP_32_64(rotr):
 643             if (temps[args[1]].state == TCG_TEMP_CONST
 644                 && temps[args[1]].val == 0) {
 645                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], 0);
 646                 args += 3;
 647                 gen_args += 2;
 648                 continue;
 649             }
 650             break;
 651         CASE_OP_32_64(sub):
 652             {
 653                 TCGOpcode neg_op;
 654                 bool have_neg;
 655
 656                 if (temps[args[2]].state == TCG_TEMP_CONST) {
 657                     /* Proceed with possible constant folding. */
 658                     break;
 659                 }
 660                 if (op == INDEX_op_sub_i32) {
 661                     neg_op = INDEX_op_neg_i32;
 662                     have_neg = TCG_TARGET_HAS_neg_i32;
 663                 } else {
 664                     neg_op = INDEX_op_neg_i64;
 665                     have_neg = TCG_TARGET_HAS_neg_i64;
 666                 }
 667                 if (!have_neg) {
 668                     break;
 669                 }
 670                 if (temps[args[1]].state == TCG_TEMP_CONST
 671                     && temps[args[1]].val == 0) {
 672                     s->gen_opc_buf[op_index] = neg_op;
 673                     reset_temp(args[0]);
 674                     gen_args[0] = args[0];
 675                     gen_args[1] = args[2];
 676                     args += 3;
 677                     gen_args += 2;
 678                     continue;
 679                 }
 680             }
 681             break;
 682         CASE_OP_32_64(xor):
 683         CASE_OP_32_64(nand):
 684             if (temps[args[1]].state != TCG_TEMP_CONST
 685                 && temps[args[2]].state == TCG_TEMP_CONST
 686                 && temps[args[2]].val == -1) {
 687                 i = 1;
 688                 goto try_not;
 689             }
 690             break;
 691         CASE_OP_32_64(nor):
 692             if (temps[args[1]].state != TCG_TEMP_CONST
 693                 && temps[args[2]].state == TCG_TEMP_CONST
 694                 && temps[args[2]].val == 0) {
 695                 i = 1;
 696                 goto try_not;
 697             }
 698             break;
 699         CASE_OP_32_64(andc):
 700             if (temps[args[2]].state != TCG_TEMP_CONST
 701                 && temps[args[1]].state == TCG_TEMP_CONST
 702                 && temps[args[1]].val == -1) {
 703                 i = 2;
 704                 goto try_not;
 705             }
 706             break;
 707         CASE_OP_32_64(orc):
 708         CASE_OP_32_64(eqv):
 709             if (temps[args[2]].state != TCG_TEMP_CONST
 710                 && temps[args[1]].state == TCG_TEMP_CONST
 711                 && temps[args[1]].val == 0) {
 712                 i = 2;
 713                 goto try_not;
 714             }
 715             break;
 716         try_not:
 717             {
 718                 TCGOpcode not_op;
 719                 bool have_not;
 720
 721                 if (def->flags & TCG_OPF_64BIT) {
 722                     not_op = INDEX_op_not_i64;
 723                     have_not = TCG_TARGET_HAS_not_i64;
 724                 } else {
 725                     not_op = INDEX_op_not_i32;
 726                     have_not = TCG_TARGET_HAS_not_i32;
 727                 }
 728                 if (!have_not) {
 729                     break;
 730                 }
 731                 s->gen_opc_buf[op_index] = not_op;
 732                 reset_temp(args[0]);
 733                 gen_args[0] = args[0];
 734                 gen_args[1] = args[i];
 735                 args += 3;
 736                 gen_args += 2;
 737                 continue;
 738             }
 739         default:
 740             break;
 741         }
 742
 743         /* Simplify expression for "op r, a, const => mov r, a" cases */
 744         switch (op) {
 745         CASE_OP_32_64(add):
 746         CASE_OP_32_64(sub):
 747         CASE_OP_32_64(shl):
 748         CASE_OP_32_64(shr):
 749         CASE_OP_32_64(sar):
 750         CASE_OP_32_64(rotl):
 751         CASE_OP_32_64(rotr):
 752         CASE_OP_32_64(or):
 753         CASE_OP_32_64(xor):
 754         CASE_OP_32_64(andc):
 755             if (temps[args[1]].state != TCG_TEMP_CONST
 756                 && temps[args[2]].state == TCG_TEMP_CONST
 757                 && temps[args[2]].val == 0) {
 758                 goto do_mov3;
 759             }
 760             break;
 761         CASE_OP_32_64(and):
 762         CASE_OP_32_64(orc):
 763         CASE_OP_32_64(eqv):
 764             if (temps[args[1]].state != TCG_TEMP_CONST
 765                 && temps[args[2]].state == TCG_TEMP_CONST
 766                 && temps[args[2]].val == -1) {
 767                 goto do_mov3;
 768             }
 769             break;
 770         do_mov3:
 771             if (temps_are_copies(args[0], args[1])) {
 772                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 773             } else {
 774                 tcg_opt_gen_mov(s, op_index, gen_args, op, args[0], args[1]);
 775                 gen_args += 2;
 776             }
 777             args += 3;
 778             continue;
 779         default:
 780             break;
 781         }
 782
 783         /* Simplify using known-zero bits. Currently only ops with a single
 784            output argument is supported. */
 785         mask = -1;
 786         affected = -1;
 787         switch (op) {
 788         CASE_OP_32_64(ext8s):
 789             if ((temps[args[1]].mask & 0x80) != 0) {
 790                 break;
 791             }
 792         CASE_OP_32_64(ext8u):
 793             mask = 0xff;
 794             goto and_const;
 795         CASE_OP_32_64(ext16s):
 796             if ((temps[args[1]].mask & 0x8000) != 0) {
 797                 break;
 798             }
 799         CASE_OP_32_64(ext16u):
 800             mask = 0xffff;
 801             goto and_const;
 802         case INDEX_op_ext32s_i64:
 803             if ((temps[args[1]].mask & 0x80000000) != 0) {
 804                 break;
 805             }
 806         case INDEX_op_ext32u_i64:
 807             mask = 0xffffffffU;
 808             goto and_const;
 809
 810         CASE_OP_32_64(and):
 811             mask = temps[args[2]].mask;
 812             if (temps[args[2]].state == TCG_TEMP_CONST) {
 813         and_const:
 814                 affected = temps[args[1]].mask & ~mask;
 815             }
 816             mask = temps[args[1]].mask & mask;
 817             break;
 818
 819         CASE_OP_32_64(andc):
 820             /* Known-zeros does not imply known-ones.  Therefore unless
 821                args[2] is constant, we can't infer anything from it.  */
 822             if (temps[args[2]].state == TCG_TEMP_CONST) {
 823                 mask = ~temps[args[2]].mask;
 824                 goto and_const;
 825             }
 826             /* But we certainly know nothing outside args[1] may be set. */
 827             mask = temps[args[1]].mask;
 828             break;
 829
 830         case INDEX_op_sar_i32:
 831             if (temps[args[2]].state == TCG_TEMP_CONST) {
 832                 tmp = temps[args[2]].val & 31;
 833                 mask = (int32_t)temps[args[1]].mask >> tmp;
 834             }
 835             break;
 836         case INDEX_op_sar_i64:
 837             if (temps[args[2]].state == TCG_TEMP_CONST) {
 838                 tmp = temps[args[2]].val & 63;
 839                 mask = (int64_t)temps[args[1]].mask >> tmp;
 840             }
 841             break;
 842
 843         case INDEX_op_shr_i32:
 844             if (temps[args[2]].state == TCG_TEMP_CONST) {
 845                 tmp = temps[args[2]].val & 31;
 846                 mask = (uint32_t)temps[args[1]].mask >> tmp;
 847             }
 848             break;
 849         case INDEX_op_shr_i64:
 850             if (temps[args[2]].state == TCG_TEMP_CONST) {
 851                 tmp = temps[args[2]].val & 63;
 852                 mask = (uint64_t)temps[args[1]].mask >> tmp;
 853             }
 854             break;
 855
 856         case INDEX_op_trunc_shr_i32:
 857             mask = (uint64_t)temps[args[1]].mask >> args[2];
 858             break;
 859
 860         CASE_OP_32_64(shl):
 861             if (temps[args[2]].state == TCG_TEMP_CONST) {
 862                 tmp = temps[args[2]].val & (TCG_TARGET_REG_BITS - 1);
 863                 mask = temps[args[1]].mask << tmp;
 864             }
 865             break;
 866
 867         CASE_OP_32_64(neg):
 868             /* Set to 1 all bits to the left of the rightmost.  */
 869             mask = -(temps[args[1]].mask & -temps[args[1]].mask);
 870             break;
 871
 872         CASE_OP_32_64(deposit):
 873             mask = deposit64(temps[args[1]].mask, args[3], args[4],
 874                              temps[args[2]].mask);
 875             break;
 876
 877         CASE_OP_32_64(or):
 878         CASE_OP_32_64(xor):
 879             mask = temps[args[1]].mask | temps[args[2]].mask;
 880             break;
 881
 882         CASE_OP_32_64(setcond):
 883         case INDEX_op_setcond2_i32:
 884             mask = 1;
 885             break;
 886
 887         CASE_OP_32_64(movcond):
 888             mask = temps[args[3]].mask | temps[args[4]].mask;
 889             break;
 890
 891         CASE_OP_32_64(ld8u):
 892             mask = 0xff;
 893             break;
 894         CASE_OP_32_64(ld16u):
 895             mask = 0xffff;
 896             break;
 897         case INDEX_op_ld32u_i64:
 898             mask = 0xffffffffu;
 899             break;
 900
 901         CASE_OP_32_64(qemu_ld):
 902             {
 903                 TCGMemOp mop = args[nb_oargs + nb_iargs];
 904                 if (!(mop & MO_SIGN)) {
 905                     mask = (2ULL << ((8 << (mop & MO_SIZE)) - 1)) - 1;
 906                 }
 907             }
 908             break;
 909
 910         default:
 911             break;
 912         }
 913
 914         /* 32-bit ops (non 64-bit ops and non load/store ops) generate
 915            32-bit results.  For the result is zero test below, we can
 916            ignore high bits, but for further optimizations we need to
 917            record that the high bits contain garbage.  */
 918         partmask = mask;
 919         if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_64BIT))) {
 920             mask |= ~(tcg_target_ulong)0xffffffffu;
 921             partmask &= 0xffffffffu;
 922             affected &= 0xffffffffu;
 923         }
 924
 925         if (partmask == 0) {
 926             assert(nb_oargs == 1);
 927             tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], 0);
 928             args += nb_args;
 929             gen_args += 2;
 930             continue;
 931         }
 932         if (affected == 0) {
 933             assert(nb_oargs == 1);
 934             if (temps_are_copies(args[0], args[1])) {
 935                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 936             } else if (temps[args[1]].state != TCG_TEMP_CONST) {
 937                 tcg_opt_gen_mov(s, op_index, gen_args, op, args[0], args[1]);
 938                 gen_args += 2;
 939             } else {
 940                 tcg_opt_gen_movi(s, op_index, gen_args, op,
 941                                  args[0], temps[args[1]].val);
 942                 gen_args += 2;
 943             }
 944             args += nb_args;
 945             continue;
 946         }
 947
 948         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 949         switch (op) {
 950         CASE_OP_32_64(and):
 951         CASE_OP_32_64(mul):
 952         CASE_OP_32_64(muluh):
 953         CASE_OP_32_64(mulsh):
 954             if ((temps[args[2]].state == TCG_TEMP_CONST
 955                 && temps[args[2]].val == 0)) {
 956                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], 0);
 957                 args += 3;
 958                 gen_args += 2;
 959                 continue;
 960             }
 961             break;
 962         default:
 963             break;
 964         }
 965
 966         /* Simplify expression for "op r, a, a => mov r, a" cases */
 967         switch (op) {
 968         CASE_OP_32_64(or):
 969         CASE_OP_32_64(and):
 970             if (temps_are_copies(args[1], args[2])) {
 971                 if (temps_are_copies(args[0], args[1])) {
 972                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 973                 } else {
 974                     tcg_opt_gen_mov(s, op_index, gen_args, op,
 975                                     args[0], args[1]);
 976                     gen_args += 2;
 977                 }
 978                 args += 3;
 979                 continue;
 980             }
 981             break;
 982         default:
 983             break;
 984         }
 985
 986         /* Simplify expression for "op r, a, a => movi r, 0" cases */
 987         switch (op) {
 988         CASE_OP_32_64(andc):
 989         CASE_OP_32_64(sub):
 990         CASE_OP_32_64(xor):
 991             if (temps_are_copies(args[1], args[2])) {
 992                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], 0);
 993                 gen_args += 2;
 994                 args += 3;
 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 (op) {
1006         CASE_OP_32_64(mov):
1007             if (temps_are_copies(args[0], args[1])) {
1008                 args += 2;
1009                 s->gen_opc_buf[op_index] = INDEX_op_nop;
1010                 break;
1011             }
1012             if (temps[args[1]].state != TCG_TEMP_CONST) {
1013                 tcg_opt_gen_mov(s, op_index, gen_args, op, args[0], args[1]);
1014                 gen_args += 2;
1015                 args += 2;
1016                 break;
1017             }
1018             /* Source argument is constant.  Rewrite the operation and
1019                let movi case handle it. */
1020             args[1] = temps[args[1]].val;
1021             /* fallthrough */
1022         CASE_OP_32_64(movi):
1023             tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], args[1]);
1024             gen_args += 2;
1025             args += 2;
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(op, temps[args[1]].val, 0);
1038                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], tmp);
1039                 gen_args += 2;
1040                 args += 2;
1041                 break;
1042             }
1043             goto do_default;
1044
1045         case INDEX_op_trunc_shr_i32:
1046             if (temps[args[1]].state == TCG_TEMP_CONST) {
1047                 tmp = do_constant_folding(op, temps[args[1]].val, args[2]);
1048                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], tmp);
1049                 gen_args += 2;
1050                 args += 3;
1051                 break;
1052             }
1053             goto do_default;
1054
1055         CASE_OP_32_64(add):
1056         CASE_OP_32_64(sub):
1057         CASE_OP_32_64(mul):
1058         CASE_OP_32_64(or):
1059         CASE_OP_32_64(and):
1060         CASE_OP_32_64(xor):
1061         CASE_OP_32_64(shl):
1062         CASE_OP_32_64(shr):
1063         CASE_OP_32_64(sar):
1064         CASE_OP_32_64(rotl):
1065         CASE_OP_32_64(rotr):
1066         CASE_OP_32_64(andc):
1067         CASE_OP_32_64(orc):
1068         CASE_OP_32_64(eqv):
1069         CASE_OP_32_64(nand):
1070         CASE_OP_32_64(nor):
1071         CASE_OP_32_64(muluh):
1072         CASE_OP_32_64(mulsh):
1073         CASE_OP_32_64(div):
1074         CASE_OP_32_64(divu):
1075         CASE_OP_32_64(rem):
1076         CASE_OP_32_64(remu):
1077             if (temps[args[1]].state == TCG_TEMP_CONST
1078                 && temps[args[2]].state == TCG_TEMP_CONST) {
1079                 tmp = do_constant_folding(op, temps[args[1]].val,
1080                                           temps[args[2]].val);
1081                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], tmp);
1082                 gen_args += 2;
1083                 args += 3;
1084                 break;
1085             }
1086             goto do_default;
1087
1088         CASE_OP_32_64(deposit):
1089             if (temps[args[1]].state == TCG_TEMP_CONST
1090                 && temps[args[2]].state == TCG_TEMP_CONST) {
1091                 tmp = deposit64(temps[args[1]].val, args[3], args[4],
1092                                 temps[args[2]].val);
1093                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], tmp);
1094                 gen_args += 2;
1095                 args += 5;
1096                 break;
1097             }
1098             goto do_default;
1099
1100         CASE_OP_32_64(setcond):
1101             tmp = do_constant_folding_cond(op, args[1], args[2], args[3]);
1102             if (tmp != 2) {
1103                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], tmp);
1104                 gen_args += 2;
1105                 args += 4;
1106                 break;
1107             }
1108             goto do_default;
1109
1110         CASE_OP_32_64(brcond):
1111             tmp = do_constant_folding_cond(op, args[0], args[1], args[2]);
1112             if (tmp != 2) {
1113                 if (tmp) {
1114                     reset_all_temps(nb_temps);
1115                     s->gen_opc_buf[op_index] = INDEX_op_br;
1116                     gen_args[0] = args[3];
1117                     gen_args += 1;
1118                 } else {
1119                     s->gen_opc_buf[op_index] = INDEX_op_nop;
1120                 }
1121                 args += 4;
1122                 break;
1123             }
1124             goto do_default;
1125
1126         CASE_OP_32_64(movcond):
1127             tmp = do_constant_folding_cond(op, args[1], args[2], args[5]);
1128             if (tmp != 2) {
1129                 if (temps_are_copies(args[0], args[4-tmp])) {
1130                     s->gen_opc_buf[op_index] = INDEX_op_nop;
1131                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
1132                     tcg_opt_gen_movi(s, op_index, gen_args, op,
1133                                      args[0], temps[args[4-tmp]].val);
1134                     gen_args += 2;
1135                 } else {
1136                     tcg_opt_gen_mov(s, op_index, gen_args, op,
1137                                     args[0], args[4-tmp]);
1138                     gen_args += 2;
1139                 }
1140                 args += 6;
1141                 break;
1142             }
1143             goto do_default;
1144
1145         case INDEX_op_add2_i32:
1146         case INDEX_op_sub2_i32:
1147             if (temps[args[2]].state == TCG_TEMP_CONST
1148                 && temps[args[3]].state == TCG_TEMP_CONST
1149                 && temps[args[4]].state == TCG_TEMP_CONST
1150                 && temps[args[5]].state == TCG_TEMP_CONST) {
1151                 uint32_t al = temps[args[2]].val;
1152                 uint32_t ah = temps[args[3]].val;
1153                 uint32_t bl = temps[args[4]].val;
1154                 uint32_t bh = temps[args[5]].val;
1155                 uint64_t a = ((uint64_t)ah << 32) | al;
1156                 uint64_t b = ((uint64_t)bh << 32) | bl;
1157                 TCGArg rl, rh;
1158
1159                 if (op == INDEX_op_add2_i32) {
1160                     a += b;
1161                 } else {
1162                     a -= b;
1163                 }
1164
1165                 /* We emit the extra nop when we emit the add2/sub2.  */
1166                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
1167
1168                 rl = args[0];
1169                 rh = args[1];
1170                 tcg_opt_gen_movi(s, op_index, &gen_args[0],
1171                                  op, rl, (uint32_t)a);
1172                 tcg_opt_gen_movi(s, ++op_index, &gen_args[2],
1173                                  op, rh, (uint32_t)(a >> 32));
1174                 gen_args += 4;
1175                 args += 6;
1176                 break;
1177             }
1178             goto do_default;
1179
1180         case INDEX_op_mulu2_i32:
1181             if (temps[args[2]].state == TCG_TEMP_CONST
1182                 && temps[args[3]].state == TCG_TEMP_CONST) {
1183                 uint32_t a = temps[args[2]].val;
1184                 uint32_t b = temps[args[3]].val;
1185                 uint64_t r = (uint64_t)a * b;
1186                 TCGArg rl, rh;
1187
1188                 /* We emit the extra nop when we emit the mulu2.  */
1189                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
1190
1191                 rl = args[0];
1192                 rh = args[1];
1193                 tcg_opt_gen_movi(s, op_index, &gen_args[0],
1194                                  op, rl, (uint32_t)r);
1195                 tcg_opt_gen_movi(s, ++op_index, &gen_args[2],
1196                                  op, rh, (uint32_t)(r >> 32));
1197                 gen_args += 4;
1198                 args += 4;
1199                 break;
1200             }
1201             goto do_default;
1202
1203         case INDEX_op_brcond2_i32:
1204             tmp = do_constant_folding_cond2(&args[0], &args[2], args[4]);
1205             if (tmp != 2) {
1206                 if (tmp) {
1207             do_brcond_true:
1208                     reset_all_temps(nb_temps);
1209                     s->gen_opc_buf[op_index] = INDEX_op_br;
1210                     gen_args[0] = args[5];
1211                     gen_args += 1;
1212                 } else {
1213             do_brcond_false:
1214                     s->gen_opc_buf[op_index] = INDEX_op_nop;
1215                 }
1216             } else if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
1217                        && temps[args[2]].state == TCG_TEMP_CONST
1218                        && temps[args[3]].state == TCG_TEMP_CONST
1219                        && temps[args[2]].val == 0
1220                        && temps[args[3]].val == 0) {
1221                 /* Simplify LT/GE comparisons vs zero to a single compare
1222                    vs the high word of the input.  */
1223             do_brcond_high:
1224                 reset_all_temps(nb_temps);
1225                 s->gen_opc_buf[op_index] = INDEX_op_brcond_i32;
1226                 gen_args[0] = args[1];
1227                 gen_args[1] = args[3];
1228                 gen_args[2] = args[4];
1229                 gen_args[3] = args[5];
1230                 gen_args += 4;
1231             } else if (args[4] == TCG_COND_EQ) {
1232                 /* Simplify EQ comparisons where one of the pairs
1233                    can be simplified.  */
1234                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1235                                                args[0], args[2], TCG_COND_EQ);
1236                 if (tmp == 0) {
1237                     goto do_brcond_false;
1238                 } else if (tmp == 1) {
1239                     goto do_brcond_high;
1240                 }
1241                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1242                                                args[1], args[3], TCG_COND_EQ);
1243                 if (tmp == 0) {
1244                     goto do_brcond_false;
1245                 } else if (tmp != 1) {
1246                     goto do_default;
1247                 }
1248             do_brcond_low:
1249                 reset_all_temps(nb_temps);
1250                 s->gen_opc_buf[op_index] = INDEX_op_brcond_i32;
1251                 gen_args[0] = args[0];
1252                 gen_args[1] = args[2];
1253                 gen_args[2] = args[4];
1254                 gen_args[3] = args[5];
1255                 gen_args += 4;
1256             } else if (args[4] == TCG_COND_NE) {
1257                 /* Simplify NE comparisons where one of the pairs
1258                    can be simplified.  */
1259                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1260                                                args[0], args[2], TCG_COND_NE);
1261                 if (tmp == 0) {
1262                     goto do_brcond_high;
1263                 } else if (tmp == 1) {
1264                     goto do_brcond_true;
1265                 }
1266                 tmp = do_constant_folding_cond(INDEX_op_brcond_i32,
1267                                                args[1], args[3], TCG_COND_NE);
1268                 if (tmp == 0) {
1269                     goto do_brcond_low;
1270                 } else if (tmp == 1) {
1271                     goto do_brcond_true;
1272                 }
1273                 goto do_default;
1274             } else {
1275                 goto do_default;
1276             }
1277             args += 6;
1278             break;
1279
1280         case INDEX_op_setcond2_i32:
1281             tmp = do_constant_folding_cond2(&args[1], &args[3], args[5]);
1282             if (tmp != 2) {
1283             do_setcond_const:
1284                 tcg_opt_gen_movi(s, op_index, gen_args, op, args[0], tmp);
1285                 gen_args += 2;
1286             } else if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
1287                        && temps[args[3]].state == TCG_TEMP_CONST
1288                        && temps[args[4]].state == TCG_TEMP_CONST
1289                        && temps[args[3]].val == 0
1290                        && temps[args[4]].val == 0) {
1291                 /* Simplify LT/GE comparisons vs zero to a single compare
1292                    vs the high word of the input.  */
1293             do_setcond_high:
1294                 s->gen_opc_buf[op_index] = INDEX_op_setcond_i32;
1295                 reset_temp(args[0]);
1296                 temps[args[0]].mask = 1;
1297                 gen_args[0] = args[0];
1298                 gen_args[1] = args[2];
1299                 gen_args[2] = args[4];
1300                 gen_args[3] = args[5];
1301                 gen_args += 4;
1302             } else if (args[5] == TCG_COND_EQ) {
1303                 /* Simplify EQ comparisons where one of the pairs
1304                    can be simplified.  */
1305                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1306                                                args[1], args[3], TCG_COND_EQ);
1307                 if (tmp == 0) {
1308                     goto do_setcond_const;
1309                 } else if (tmp == 1) {
1310                     goto do_setcond_high;
1311                 }
1312                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1313                                                args[2], args[4], TCG_COND_EQ);
1314                 if (tmp == 0) {
1315                     goto do_setcond_high;
1316                 } else if (tmp != 1) {
1317                     goto do_default;
1318                 }
1319             do_setcond_low:
1320                 reset_temp(args[0]);
1321                 temps[args[0]].mask = 1;
1322                 s->gen_opc_buf[op_index] = INDEX_op_setcond_i32;
1323                 gen_args[0] = args[0];
1324                 gen_args[1] = args[1];
1325                 gen_args[2] = args[3];
1326                 gen_args[3] = args[5];
1327                 gen_args += 4;
1328             } else if (args[5] == TCG_COND_NE) {
1329                 /* Simplify NE comparisons where one of the pairs
1330                    can be simplified.  */
1331                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1332                                                args[1], args[3], TCG_COND_NE);
1333                 if (tmp == 0) {
1334                     goto do_setcond_high;
1335                 } else if (tmp == 1) {
1336                     goto do_setcond_const;
1337                 }
1338                 tmp = do_constant_folding_cond(INDEX_op_setcond_i32,
1339                                                args[2], args[4], TCG_COND_NE);
1340                 if (tmp == 0) {
1341                     goto do_setcond_low;
1342                 } else if (tmp == 1) {
1343                     goto do_setcond_const;
1344                 }
1345                 goto do_default;
1346             } else {
1347                 goto do_default;
1348             }
1349             args += 6;
1350             break;
1351
1352         case INDEX_op_call:
1353             if (!(args[nb_oargs + nb_iargs + 1]
1354                   & (TCG_CALL_NO_READ_GLOBALS | TCG_CALL_NO_WRITE_GLOBALS))) {
1355                 for (i = 0; i < nb_globals; i++) {
1356                     reset_temp(i);
1357                 }
1358             }
1359             goto do_reset_output;
1360
1361         default:
1362         do_default:
1363             /* Default case: we know nothing about operation (or were unable
1364                to compute the operation result) so no propagation is done.
1365                We trash everything if the operation is the end of a basic
1366                block, otherwise we only trash the output args.  "mask" is
1367                the non-zero bits mask for the first output arg.  */
1368             if (def->flags & TCG_OPF_BB_END) {
1369                 reset_all_temps(nb_temps);
1370             } else {
1371         do_reset_output:
1372                 for (i = 0; i < nb_oargs; i++) {
1373                     reset_temp(args[i]);
1374                     /* Save the corresponding known-zero bits mask for the
1375                        first output argument (only one supported so far). */
1376                     if (i == 0) {
1377                         temps[args[i]].mask = mask;
1378                     }
1379                 }
1380             }
1381             for (i = 0; i < nb_args; i++) {
1382                 gen_args[i] = args[i];
1383             }
1384             args += nb_args;
1385             gen_args += nb_args;
1386             break;
1387         }
1388     }
1389
1390     return gen_args;
1391 }
1392
1393 TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
1394         TCGArg *args, TCGOpDef *tcg_op_defs)
1395 {
1396     TCGArg *res;
1397     res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
1398     return res;
1399 }