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_HAS_COPY,
  43     TCG_TEMP_ANY
  44 } tcg_temp_state;
  45
  46 struct tcg_temp_info {
  47     tcg_temp_state state;
  48     uint16_t prev_copy;
  49     uint16_t next_copy;
  50     tcg_target_ulong val;
  51 };
  52
  53 static struct tcg_temp_info temps[TCG_MAX_TEMPS];
  54
  55 /* Reset TEMP's state to TCG_TEMP_ANY.  If TEMP was a representative of some
  56    class of equivalent temp's, a new representative should be chosen in this
  57    class. */
  58 static void reset_temp(TCGArg temp, int nb_temps, int nb_globals)
  59 {
  60     int i;
  61     TCGArg new_base = (TCGArg)-1;
  62     if (temps[temp].state == TCG_TEMP_HAS_COPY) {
  63         for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
  64             if (i >= nb_globals) {
  65                 temps[i].state = TCG_TEMP_HAS_COPY;
  66                 new_base = i;
  67                 break;
  68             }
  69         }
  70         for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
  71             if (new_base == (TCGArg)-1) {
  72                 temps[i].state = TCG_TEMP_ANY;
  73             } else {
  74                 temps[i].val = new_base;
  75             }
  76         }
  77         temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
  78         temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
  79     } else if (temps[temp].state == TCG_TEMP_COPY) {
  80         temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
  81         temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
  82         new_base = temps[temp].val;
  83     }
  84     temps[temp].state = TCG_TEMP_ANY;
  85     if (new_base != (TCGArg)-1 && temps[new_base].next_copy == new_base) {
  86         temps[new_base].state = TCG_TEMP_ANY;
  87     }
  88 }
  89
  90 static int op_bits(TCGOpcode op)
  91 {
  92     const TCGOpDef *def = &tcg_op_defs[op];
  93     return def->flags & TCG_OPF_64BIT ? 64 : 32;
  94 }
  95
  96 static TCGOpcode op_to_movi(TCGOpcode op)
  97 {
  98     switch (op_bits(op)) {
  99     case 32:
 100         return INDEX_op_movi_i32;
 101     case 64:
 102         return INDEX_op_movi_i64;
 103     default:
 104         fprintf(stderr, "op_to_movi: unexpected return value of "
 105                 "function op_bits.\n");
 106         tcg_abort();
 107     }
 108 }
 109
 110 static void tcg_opt_gen_mov(TCGArg *gen_args, TCGArg dst, TCGArg src,
 111                             int nb_temps, int nb_globals)
 112 {
 113         reset_temp(dst, nb_temps, nb_globals);
 114         assert(temps[src].state != TCG_TEMP_COPY);
 115         if (src >= nb_globals) {
 116             assert(temps[src].state != TCG_TEMP_CONST);
 117             if (temps[src].state != TCG_TEMP_HAS_COPY) {
 118                 temps[src].state = TCG_TEMP_HAS_COPY;
 119                 temps[src].next_copy = src;
 120                 temps[src].prev_copy = src;
 121             }
 122             temps[dst].state = TCG_TEMP_COPY;
 123             temps[dst].val = src;
 124             temps[dst].next_copy = temps[src].next_copy;
 125             temps[dst].prev_copy = src;
 126             temps[temps[dst].next_copy].prev_copy = dst;
 127             temps[src].next_copy = dst;
 128         }
 129         gen_args[0] = dst;
 130         gen_args[1] = src;
 131 }
 132
 133 static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val,
 134                              int nb_temps, int nb_globals)
 135 {
 136         reset_temp(dst, nb_temps, nb_globals);
 137         temps[dst].state = TCG_TEMP_CONST;
 138         temps[dst].val = val;
 139         gen_args[0] = dst;
 140         gen_args[1] = val;
 141 }
 142
 143 static TCGOpcode op_to_mov(TCGOpcode op)
 144 {
 145     switch (op_bits(op)) {
 146     case 32:
 147         return INDEX_op_mov_i32;
 148     case 64:
 149         return INDEX_op_mov_i64;
 150     default:
 151         fprintf(stderr, "op_to_mov: unexpected return value of "
 152                 "function op_bits.\n");
 153         tcg_abort();
 154     }
 155 }
 156
 157 static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
 158 {
 159     switch (op) {
 160     CASE_OP_32_64(add):
 161         return x + y;
 162
 163     CASE_OP_32_64(sub):
 164         return x - y;
 165
 166     CASE_OP_32_64(mul):
 167         return x * y;
 168
 169     CASE_OP_32_64(and):
 170         return x & y;
 171
 172     CASE_OP_32_64(or):
 173         return x | y;
 174
 175     CASE_OP_32_64(xor):
 176         return x ^ y;
 177
 178     case INDEX_op_shl_i32:
 179         return (uint32_t)x << (uint32_t)y;
 180
 181     case INDEX_op_shl_i64:
 182         return (uint64_t)x << (uint64_t)y;
 183
 184     case INDEX_op_shr_i32:
 185         return (uint32_t)x >> (uint32_t)y;
 186
 187     case INDEX_op_shr_i64:
 188         return (uint64_t)x >> (uint64_t)y;
 189
 190     case INDEX_op_sar_i32:
 191         return (int32_t)x >> (int32_t)y;
 192
 193     case INDEX_op_sar_i64:
 194         return (int64_t)x >> (int64_t)y;
 195
 196     case INDEX_op_rotr_i32:
 197         x = ((uint32_t)x << (32 - y)) | ((uint32_t)x >> y);
 198         return x;
 199
 200     case INDEX_op_rotr_i64:
 201         x = ((uint64_t)x << (64 - y)) | ((uint64_t)x >> y);
 202         return x;
 203
 204     case INDEX_op_rotl_i32:
 205         x = ((uint32_t)x << y) | ((uint32_t)x >> (32 - y));
 206         return x;
 207
 208     case INDEX_op_rotl_i64:
 209         x = ((uint64_t)x << y) | ((uint64_t)x >> (64 - y));
 210         return x;
 211
 212     CASE_OP_32_64(not):
 213         return ~x;
 214
 215     CASE_OP_32_64(neg):
 216         return -x;
 217
 218     CASE_OP_32_64(andc):
 219         return x & ~y;
 220
 221     CASE_OP_32_64(orc):
 222         return x | ~y;
 223
 224     CASE_OP_32_64(eqv):
 225         return ~(x ^ y);
 226
 227     CASE_OP_32_64(nand):
 228         return ~(x & y);
 229
 230     CASE_OP_32_64(nor):
 231         return ~(x | y);
 232
 233     CASE_OP_32_64(ext8s):
 234         return (int8_t)x;
 235
 236     CASE_OP_32_64(ext16s):
 237         return (int16_t)x;
 238
 239     CASE_OP_32_64(ext8u):
 240         return (uint8_t)x;
 241
 242     CASE_OP_32_64(ext16u):
 243         return (uint16_t)x;
 244
 245     case INDEX_op_ext32s_i64:
 246         return (int32_t)x;
 247
 248     case INDEX_op_ext32u_i64:
 249         return (uint32_t)x;
 250
 251     default:
 252         fprintf(stderr,
 253                 "Unrecognized operation %d in do_constant_folding.\n", op);
 254         tcg_abort();
 255     }
 256 }
 257
 258 static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
 259 {
 260     TCGArg res = do_constant_folding_2(op, x, y);
 261     if (op_bits(op) == 32) {
 262         res &= 0xffffffff;
 263     }
 264     return res;
 265 }
 266
 267 static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
 268                                        TCGArg y, TCGCond c)
 269 {
 270     switch (op_bits(op)) {
 271     case 32:
 272         switch (c) {
 273         case TCG_COND_EQ:
 274             return (uint32_t)x == (uint32_t)y;
 275         case TCG_COND_NE:
 276             return (uint32_t)x != (uint32_t)y;
 277         case TCG_COND_LT:
 278             return (int32_t)x < (int32_t)y;
 279         case TCG_COND_GE:
 280             return (int32_t)x >= (int32_t)y;
 281         case TCG_COND_LE:
 282             return (int32_t)x <= (int32_t)y;
 283         case TCG_COND_GT:
 284             return (int32_t)x > (int32_t)y;
 285         case TCG_COND_LTU:
 286             return (uint32_t)x < (uint32_t)y;
 287         case TCG_COND_GEU:
 288             return (uint32_t)x >= (uint32_t)y;
 289         case TCG_COND_LEU:
 290             return (uint32_t)x <= (uint32_t)y;
 291         case TCG_COND_GTU:
 292             return (uint32_t)x > (uint32_t)y;
 293         }
 294         break;
 295     case 64:
 296         switch (c) {
 297         case TCG_COND_EQ:
 298             return (uint64_t)x == (uint64_t)y;
 299         case TCG_COND_NE:
 300             return (uint64_t)x != (uint64_t)y;
 301         case TCG_COND_LT:
 302             return (int64_t)x < (int64_t)y;
 303         case TCG_COND_GE:
 304             return (int64_t)x >= (int64_t)y;
 305         case TCG_COND_LE:
 306             return (int64_t)x <= (int64_t)y;
 307         case TCG_COND_GT:
 308             return (int64_t)x > (int64_t)y;
 309         case TCG_COND_LTU:
 310             return (uint64_t)x < (uint64_t)y;
 311         case TCG_COND_GEU:
 312             return (uint64_t)x >= (uint64_t)y;
 313         case TCG_COND_LEU:
 314             return (uint64_t)x <= (uint64_t)y;
 315         case TCG_COND_GTU:
 316             return (uint64_t)x > (uint64_t)y;
 317         }
 318         break;
 319     }
 320
 321     fprintf(stderr,
 322             "Unrecognized bitness %d or condition %d in "
 323             "do_constant_folding_cond.\n", op_bits(op), c);
 324     tcg_abort();
 325 }
 326
 327
 328 /* Propagate constants and copies, fold constant expressions. */
 329 static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
 330                                     TCGArg *args, TCGOpDef *tcg_op_defs)
 331 {
 332     int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;
 333     TCGOpcode op;
 334     const TCGOpDef *def;
 335     TCGArg *gen_args;
 336     TCGArg tmp;
 337     /* Array VALS has an element for each temp.
 338        If this temp holds a constant then its value is kept in VALS' element.
 339        If this temp is a copy of other ones then this equivalence class'
 340        representative is kept in VALS' element.
 341        If this temp is neither copy nor constant then corresponding VALS'
 342        element is unused. */
 343
 344     nb_temps = s->nb_temps;
 345     nb_globals = s->nb_globals;
 346     memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 347
 348     nb_ops = tcg_opc_ptr - gen_opc_buf;
 349     gen_args = args;
 350     for (op_index = 0; op_index < nb_ops; op_index++) {
 351         op = gen_opc_buf[op_index];
 352         def = &tcg_op_defs[op];
 353         /* Do copy propagation */
 354         if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) {
 355             assert(op != INDEX_op_call);
 356             for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
 357                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 358                     args[i] = temps[args[i]].val;
 359                 }
 360             }
 361         }
 362
 363         /* For commutative operations make constant second argument */
 364         switch (op) {
 365         CASE_OP_32_64(add):
 366         CASE_OP_32_64(mul):
 367         CASE_OP_32_64(and):
 368         CASE_OP_32_64(or):
 369         CASE_OP_32_64(xor):
 370         CASE_OP_32_64(eqv):
 371         CASE_OP_32_64(nand):
 372         CASE_OP_32_64(nor):
 373             if (temps[args[1]].state == TCG_TEMP_CONST) {
 374                 tmp = args[1];
 375                 args[1] = args[2];
 376                 args[2] = tmp;
 377             }
 378             break;
 379         CASE_OP_32_64(brcond):
 380             if (temps[args[0]].state == TCG_TEMP_CONST
 381                 && temps[args[1]].state != TCG_TEMP_CONST) {
 382                 tmp = args[0];
 383                 args[0] = args[1];
 384                 args[1] = tmp;
 385                 args[2] = tcg_swap_cond(args[2]);
 386             }
 387             break;
 388         CASE_OP_32_64(setcond):
 389             if (temps[args[1]].state == TCG_TEMP_CONST
 390                 && temps[args[2]].state != TCG_TEMP_CONST) {
 391                 tmp = args[1];
 392                 args[1] = args[2];
 393                 args[2] = tmp;
 394                 args[3] = tcg_swap_cond(args[3]);
 395             }
 396             break;
 397         default:
 398             break;
 399         }
 400
 401         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0" */
 402         switch (op) {
 403         CASE_OP_32_64(shl):
 404         CASE_OP_32_64(shr):
 405         CASE_OP_32_64(sar):
 406         CASE_OP_32_64(rotl):
 407         CASE_OP_32_64(rotr):
 408             if (temps[args[1]].state == TCG_TEMP_CONST
 409                 && temps[args[1]].val == 0) {
 410                 gen_opc_buf[op_index] = op_to_movi(op);
 411                 tcg_opt_gen_movi(gen_args, args[0], 0, nb_temps, nb_globals);
 412                 args += 3;
 413                 gen_args += 2;
 414                 continue;
 415             }
 416             break;
 417         default:
 418             break;
 419         }
 420
 421         /* Simplify expression for "op r, a, 0 => mov r, a" cases */
 422         switch (op) {
 423         CASE_OP_32_64(add):
 424         CASE_OP_32_64(sub):
 425         CASE_OP_32_64(shl):
 426         CASE_OP_32_64(shr):
 427         CASE_OP_32_64(sar):
 428         CASE_OP_32_64(rotl):
 429         CASE_OP_32_64(rotr):
 430         CASE_OP_32_64(or):
 431         CASE_OP_32_64(xor):
 432             if (temps[args[1]].state == TCG_TEMP_CONST) {
 433                 /* Proceed with possible constant folding. */
 434                 break;
 435             }
 436             if (temps[args[2]].state == TCG_TEMP_CONST
 437                 && temps[args[2]].val == 0) {
 438                 if ((temps[args[0]].state == TCG_TEMP_COPY
 439                     && temps[args[0]].val == args[1])
 440                     || args[0] == args[1]) {
 441                     gen_opc_buf[op_index] = INDEX_op_nop;
 442                 } else {
 443                     gen_opc_buf[op_index] = op_to_mov(op);
 444                     tcg_opt_gen_mov(gen_args, args[0], args[1],
 445                                     nb_temps, nb_globals);
 446                     gen_args += 2;
 447                 }
 448                 args += 3;
 449                 continue;
 450             }
 451             break;
 452         default:
 453             break;
 454         }
 455
 456         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 457         switch (op) {
 458         CASE_OP_32_64(and):
 459         CASE_OP_32_64(mul):
 460             if ((temps[args[2]].state == TCG_TEMP_CONST
 461                 && temps[args[2]].val == 0)) {
 462                 gen_opc_buf[op_index] = op_to_movi(op);
 463                 tcg_opt_gen_movi(gen_args, args[0], 0, nb_temps, nb_globals);
 464                 args += 3;
 465                 gen_args += 2;
 466                 continue;
 467             }
 468             break;
 469         default:
 470             break;
 471         }
 472
 473         /* Simplify expression for "op r, a, a => mov r, a" cases */
 474         switch (op) {
 475         CASE_OP_32_64(or):
 476         CASE_OP_32_64(and):
 477             if (args[1] == args[2]) {
 478                 if (args[1] == args[0]) {
 479                     gen_opc_buf[op_index] = INDEX_op_nop;
 480                 } else {
 481                     gen_opc_buf[op_index] = op_to_mov(op);
 482                     tcg_opt_gen_mov(gen_args, args[0], args[1], nb_temps,
 483                                     nb_globals);
 484                     gen_args += 2;
 485                 }
 486                 args += 3;
 487                 continue;
 488             }
 489             break;
 490         default:
 491             break;
 492         }
 493
 494         /* Propagate constants through copy operations and do constant
 495            folding.  Constants will be substituted to arguments by register
 496            allocator where needed and possible.  Also detect copies. */
 497         switch (op) {
 498         CASE_OP_32_64(mov):
 499             if ((temps[args[1]].state == TCG_TEMP_COPY
 500                 && temps[args[1]].val == args[0])
 501                 || args[0] == args[1]) {
 502                 args += 2;
 503                 gen_opc_buf[op_index] = INDEX_op_nop;
 504                 break;
 505             }
 506             if (temps[args[1]].state != TCG_TEMP_CONST) {
 507                 tcg_opt_gen_mov(gen_args, args[0], args[1],
 508                                 nb_temps, nb_globals);
 509                 gen_args += 2;
 510                 args += 2;
 511                 break;
 512             }
 513             /* Source argument is constant.  Rewrite the operation and
 514                let movi case handle it. */
 515             op = op_to_movi(op);
 516             gen_opc_buf[op_index] = op;
 517             args[1] = temps[args[1]].val;
 518             /* fallthrough */
 519         CASE_OP_32_64(movi):
 520             tcg_opt_gen_movi(gen_args, args[0], args[1], nb_temps, nb_globals);
 521             gen_args += 2;
 522             args += 2;
 523             break;
 524         CASE_OP_32_64(not):
 525         CASE_OP_32_64(neg):
 526         CASE_OP_32_64(ext8s):
 527         CASE_OP_32_64(ext8u):
 528         CASE_OP_32_64(ext16s):
 529         CASE_OP_32_64(ext16u):
 530         case INDEX_op_ext32s_i64:
 531         case INDEX_op_ext32u_i64:
 532             if (temps[args[1]].state == TCG_TEMP_CONST) {
 533                 gen_opc_buf[op_index] = op_to_movi(op);
 534                 tmp = do_constant_folding(op, temps[args[1]].val, 0);
 535                 tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
 536             } else {
 537                 reset_temp(args[0], nb_temps, nb_globals);
 538                 gen_args[0] = args[0];
 539                 gen_args[1] = args[1];
 540             }
 541             gen_args += 2;
 542             args += 2;
 543             break;
 544         CASE_OP_32_64(add):
 545         CASE_OP_32_64(sub):
 546         CASE_OP_32_64(mul):
 547         CASE_OP_32_64(or):
 548         CASE_OP_32_64(and):
 549         CASE_OP_32_64(xor):
 550         CASE_OP_32_64(shl):
 551         CASE_OP_32_64(shr):
 552         CASE_OP_32_64(sar):
 553         CASE_OP_32_64(rotl):
 554         CASE_OP_32_64(rotr):
 555         CASE_OP_32_64(andc):
 556         CASE_OP_32_64(orc):
 557         CASE_OP_32_64(eqv):
 558         CASE_OP_32_64(nand):
 559         CASE_OP_32_64(nor):
 560             if (temps[args[1]].state == TCG_TEMP_CONST
 561                 && temps[args[2]].state == TCG_TEMP_CONST) {
 562                 gen_opc_buf[op_index] = op_to_movi(op);
 563                 tmp = do_constant_folding(op, temps[args[1]].val,
 564                                           temps[args[2]].val);
 565                 tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
 566                 gen_args += 2;
 567             } else {
 568                 reset_temp(args[0], nb_temps, nb_globals);
 569                 gen_args[0] = args[0];
 570                 gen_args[1] = args[1];
 571                 gen_args[2] = args[2];
 572                 gen_args += 3;
 573             }
 574             args += 3;
 575             break;
 576         CASE_OP_32_64(setcond):
 577             if (temps[args[1]].state == TCG_TEMP_CONST
 578                 && temps[args[2]].state == TCG_TEMP_CONST) {
 579                 gen_opc_buf[op_index] = op_to_movi(op);
 580                 tmp = do_constant_folding_cond(op, temps[args[1]].val,
 581                                                temps[args[2]].val, args[3]);
 582                 tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
 583                 gen_args += 2;
 584             } else {
 585                 reset_temp(args[0], nb_temps, nb_globals);
 586                 gen_args[0] = args[0];
 587                 gen_args[1] = args[1];
 588                 gen_args[2] = args[2];
 589                 gen_args[3] = args[3];
 590                 gen_args += 4;
 591             }
 592             args += 4;
 593             break;
 594         CASE_OP_32_64(brcond):
 595             if (temps[args[0]].state == TCG_TEMP_CONST
 596                 && temps[args[1]].state == TCG_TEMP_CONST) {
 597                 if (do_constant_folding_cond(op, temps[args[0]].val,
 598                                              temps[args[1]].val, args[2])) {
 599                     memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 600                     gen_opc_buf[op_index] = INDEX_op_br;
 601                     gen_args[0] = args[3];
 602                     gen_args += 1;
 603                 } else {
 604                     gen_opc_buf[op_index] = INDEX_op_nop;
 605                 }
 606             } else {
 607                 memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 608                 reset_temp(args[0], nb_temps, nb_globals);
 609                 gen_args[0] = args[0];
 610                 gen_args[1] = args[1];
 611                 gen_args[2] = args[2];
 612                 gen_args[3] = args[3];
 613                 gen_args += 4;
 614             }
 615             args += 4;
 616             break;
 617         case INDEX_op_call:
 618             nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
 619             if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) {
 620                 for (i = 0; i < nb_globals; i++) {
 621                     reset_temp(i, nb_temps, nb_globals);
 622                 }
 623             }
 624             for (i = 0; i < (args[0] >> 16); i++) {
 625                 reset_temp(args[i + 1], nb_temps, nb_globals);
 626             }
 627             i = nb_call_args + 3;
 628             while (i) {
 629                 *gen_args = *args;
 630                 args++;
 631                 gen_args++;
 632                 i--;
 633             }
 634             break;
 635         case INDEX_op_set_label:
 636         case INDEX_op_jmp:
 637         case INDEX_op_br:
 638             memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 639             for (i = 0; i < def->nb_args; i++) {
 640                 *gen_args = *args;
 641                 args++;
 642                 gen_args++;
 643             }
 644             break;
 645         default:
 646             /* Default case: we do know nothing about operation so no
 647                propagation is done.  We only trash output args.  */
 648             for (i = 0; i < def->nb_oargs; i++) {
 649                 reset_temp(args[i], nb_temps, nb_globals);
 650             }
 651             for (i = 0; i < def->nb_args; i++) {
 652                 gen_args[i] = args[i];
 653             }
 654             args += def->nb_args;
 655             gen_args += def->nb_args;
 656             break;
 657         }
 658     }
 659
 660     return gen_args;
 661 }
 662
 663 TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
 664         TCGArg *args, TCGOpDef *tcg_op_defs)
 665 {
 666     TCGArg *res;
 667     res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
 668     return res;
 669 }