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_state;
  44
  45 struct tcg_temp_info {
  46     tcg_temp_state state;
  47     uint16_t prev_copy;
  48     uint16_t next_copy;
  49     tcg_target_ulong val;
  50 };
  51
  52 static struct tcg_temp_info temps[TCG_MAX_TEMPS];
  53
  54 /* Reset TEMP's state to TCG_TEMP_UNDEF.  If TEMP was a representative of some
  55    class of equivalent temp's, a new representative should be chosen in this
  56    class. */
  57 static void reset_temp(TCGArg temp, int nb_temps, int nb_globals)
  58 {
  59     int i;
  60     TCGArg new_base = (TCGArg)-1;
  61     if (temps[temp].state == TCG_TEMP_HAS_COPY) {
  62         for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
  63             if (i >= nb_globals) {
  64                 temps[i].state = TCG_TEMP_HAS_COPY;
  65                 new_base = i;
  66                 break;
  67             }
  68         }
  69         for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
  70             if (new_base == (TCGArg)-1) {
  71                 temps[i].state = TCG_TEMP_UNDEF;
  72             } else {
  73                 temps[i].val = new_base;
  74             }
  75         }
  76         temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
  77         temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
  78     } else if (temps[temp].state == TCG_TEMP_COPY) {
  79         temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
  80         temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
  81         new_base = temps[temp].val;
  82     }
  83     temps[temp].state = TCG_TEMP_UNDEF;
  84     if (new_base != (TCGArg)-1 && temps[new_base].next_copy == new_base) {
  85         temps[new_base].state = TCG_TEMP_UNDEF;
  86     }
  87 }
  88
  89 static int op_bits(TCGOpcode op)
  90 {
  91     const TCGOpDef *def = &tcg_op_defs[op];
  92     return def->flags & TCG_OPF_64BIT ? 64 : 32;
  93 }
  94
  95 static TCGOpcode op_to_movi(TCGOpcode op)
  96 {
  97     switch (op_bits(op)) {
  98     case 32:
  99         return INDEX_op_movi_i32;
 100     case 64:
 101         return INDEX_op_movi_i64;
 102     default:
 103         fprintf(stderr, "op_to_movi: unexpected return value of "
 104                 "function op_bits.\n");
 105         tcg_abort();
 106     }
 107 }
 108
 109 static void tcg_opt_gen_mov(TCGContext *s, TCGArg *gen_args,
 110                             TCGArg dst, TCGArg src)
 111 {
 112         reset_temp(dst, s->nb_temps, s->nb_globals);
 113         assert(temps[src].state != TCG_TEMP_COPY);
 114         /* Only consider temps with the same type (width) as copies. */
 115         if (src >= s->nb_globals && s->temps[dst].type == s->temps[src].type) {
 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     TCGCond cond;
 338
 339     /* Array VALS has an element for each temp.
 340        If this temp holds a constant then its value is kept in VALS' element.
 341        If this temp is a copy of other ones then this equivalence class'
 342        representative is kept in VALS' element.
 343        If this temp is neither copy nor constant then corresponding VALS'
 344        element is unused. */
 345
 346     nb_temps = s->nb_temps;
 347     nb_globals = s->nb_globals;
 348     memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 349
 350     nb_ops = tcg_opc_ptr - gen_opc_buf;
 351     gen_args = args;
 352     for (op_index = 0; op_index < nb_ops; op_index++) {
 353         op = gen_opc_buf[op_index];
 354         def = &tcg_op_defs[op];
 355         /* Do copy propagation */
 356         if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) {
 357             assert(op != INDEX_op_call);
 358             for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
 359                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 360                     args[i] = temps[args[i]].val;
 361                 }
 362             }
 363         }
 364
 365         /* For commutative operations make constant second argument */
 366         switch (op) {
 367         CASE_OP_32_64(add):
 368         CASE_OP_32_64(mul):
 369         CASE_OP_32_64(and):
 370         CASE_OP_32_64(or):
 371         CASE_OP_32_64(xor):
 372         CASE_OP_32_64(eqv):
 373         CASE_OP_32_64(nand):
 374         CASE_OP_32_64(nor):
 375             if (temps[args[1]].state == TCG_TEMP_CONST) {
 376                 tmp = args[1];
 377                 args[1] = args[2];
 378                 args[2] = tmp;
 379             }
 380             break;
 381         CASE_OP_32_64(brcond):
 382             if (temps[args[0]].state == TCG_TEMP_CONST
 383                 && temps[args[1]].state != TCG_TEMP_CONST) {
 384                 tmp = args[0];
 385                 args[0] = args[1];
 386                 args[1] = tmp;
 387                 args[2] = tcg_swap_cond(args[2]);
 388             }
 389             break;
 390         CASE_OP_32_64(setcond):
 391             if (temps[args[1]].state == TCG_TEMP_CONST
 392                 && temps[args[2]].state != TCG_TEMP_CONST) {
 393                 tmp = args[1];
 394                 args[1] = args[2];
 395                 args[2] = tmp;
 396                 args[3] = tcg_swap_cond(args[3]);
 397             }
 398             break;
 399         CASE_OP_32_64(movcond):
 400             cond = args[5];
 401             if (temps[args[1]].state == TCG_TEMP_CONST
 402                 && temps[args[2]].state != TCG_TEMP_CONST) {
 403                 tmp = args[1];
 404                 args[1] = args[2];
 405                 args[2] = tmp;
 406                 cond = tcg_swap_cond(cond);
 407             }
 408             /* For movcond, we canonicalize the "false" input reg to match
 409                the destination reg so that the tcg backend can implement
 410                a "move if true" operation.  */
 411             if (args[0] == args[3]) {
 412                 tmp = args[3];
 413                 args[3] = args[4];
 414                 args[4] = tmp;
 415                 cond = tcg_invert_cond(cond);
 416             }
 417             args[5] = cond;
 418         default:
 419             break;
 420         }
 421
 422         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0" */
 423         switch (op) {
 424         CASE_OP_32_64(shl):
 425         CASE_OP_32_64(shr):
 426         CASE_OP_32_64(sar):
 427         CASE_OP_32_64(rotl):
 428         CASE_OP_32_64(rotr):
 429             if (temps[args[1]].state == TCG_TEMP_CONST
 430                 && temps[args[1]].val == 0) {
 431                 gen_opc_buf[op_index] = op_to_movi(op);
 432                 tcg_opt_gen_movi(gen_args, args[0], 0, nb_temps, nb_globals);
 433                 args += 3;
 434                 gen_args += 2;
 435                 continue;
 436             }
 437             break;
 438         default:
 439             break;
 440         }
 441
 442         /* Simplify expression for "op r, a, 0 => mov r, a" cases */
 443         switch (op) {
 444         CASE_OP_32_64(add):
 445         CASE_OP_32_64(sub):
 446         CASE_OP_32_64(shl):
 447         CASE_OP_32_64(shr):
 448         CASE_OP_32_64(sar):
 449         CASE_OP_32_64(rotl):
 450         CASE_OP_32_64(rotr):
 451         CASE_OP_32_64(or):
 452         CASE_OP_32_64(xor):
 453             if (temps[args[1]].state == TCG_TEMP_CONST) {
 454                 /* Proceed with possible constant folding. */
 455                 break;
 456             }
 457             if (temps[args[2]].state == TCG_TEMP_CONST
 458                 && temps[args[2]].val == 0) {
 459                 if ((temps[args[0]].state == TCG_TEMP_COPY
 460                     && temps[args[0]].val == args[1])
 461                     || args[0] == args[1]) {
 462                     gen_opc_buf[op_index] = INDEX_op_nop;
 463                 } else {
 464                     gen_opc_buf[op_index] = op_to_mov(op);
 465                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 466                     gen_args += 2;
 467                 }
 468                 args += 3;
 469                 continue;
 470             }
 471             break;
 472         default:
 473             break;
 474         }
 475
 476         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 477         switch (op) {
 478         CASE_OP_32_64(and):
 479         CASE_OP_32_64(mul):
 480             if ((temps[args[2]].state == TCG_TEMP_CONST
 481                 && temps[args[2]].val == 0)) {
 482                 gen_opc_buf[op_index] = op_to_movi(op);
 483                 tcg_opt_gen_movi(gen_args, args[0], 0, nb_temps, nb_globals);
 484                 args += 3;
 485                 gen_args += 2;
 486                 continue;
 487             }
 488             break;
 489         default:
 490             break;
 491         }
 492
 493         /* Simplify expression for "op r, a, a => mov r, a" cases */
 494         switch (op) {
 495         CASE_OP_32_64(or):
 496         CASE_OP_32_64(and):
 497             if (args[1] == args[2]) {
 498                 if (args[1] == args[0]) {
 499                     gen_opc_buf[op_index] = INDEX_op_nop;
 500                 } else {
 501                     gen_opc_buf[op_index] = op_to_mov(op);
 502                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 503                     gen_args += 2;
 504                 }
 505                 args += 3;
 506                 continue;
 507             }
 508             break;
 509         default:
 510             break;
 511         }
 512
 513         /* Propagate constants through copy operations and do constant
 514            folding.  Constants will be substituted to arguments by register
 515            allocator where needed and possible.  Also detect copies. */
 516         switch (op) {
 517         CASE_OP_32_64(mov):
 518             if ((temps[args[1]].state == TCG_TEMP_COPY
 519                 && temps[args[1]].val == args[0])
 520                 || args[0] == args[1]) {
 521                 args += 2;
 522                 gen_opc_buf[op_index] = INDEX_op_nop;
 523                 break;
 524             }
 525             if (temps[args[1]].state != TCG_TEMP_CONST) {
 526                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 527                 gen_args += 2;
 528                 args += 2;
 529                 break;
 530             }
 531             /* Source argument is constant.  Rewrite the operation and
 532                let movi case handle it. */
 533             op = op_to_movi(op);
 534             gen_opc_buf[op_index] = op;
 535             args[1] = temps[args[1]].val;
 536             /* fallthrough */
 537         CASE_OP_32_64(movi):
 538             tcg_opt_gen_movi(gen_args, args[0], args[1], nb_temps, nb_globals);
 539             gen_args += 2;
 540             args += 2;
 541             break;
 542         CASE_OP_32_64(not):
 543         CASE_OP_32_64(neg):
 544         CASE_OP_32_64(ext8s):
 545         CASE_OP_32_64(ext8u):
 546         CASE_OP_32_64(ext16s):
 547         CASE_OP_32_64(ext16u):
 548         case INDEX_op_ext32s_i64:
 549         case INDEX_op_ext32u_i64:
 550             if (temps[args[1]].state == TCG_TEMP_CONST) {
 551                 gen_opc_buf[op_index] = op_to_movi(op);
 552                 tmp = do_constant_folding(op, temps[args[1]].val, 0);
 553                 tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
 554             } else {
 555                 reset_temp(args[0], nb_temps, nb_globals);
 556                 gen_args[0] = args[0];
 557                 gen_args[1] = args[1];
 558             }
 559             gen_args += 2;
 560             args += 2;
 561             break;
 562         CASE_OP_32_64(add):
 563         CASE_OP_32_64(sub):
 564         CASE_OP_32_64(mul):
 565         CASE_OP_32_64(or):
 566         CASE_OP_32_64(and):
 567         CASE_OP_32_64(xor):
 568         CASE_OP_32_64(shl):
 569         CASE_OP_32_64(shr):
 570         CASE_OP_32_64(sar):
 571         CASE_OP_32_64(rotl):
 572         CASE_OP_32_64(rotr):
 573         CASE_OP_32_64(andc):
 574         CASE_OP_32_64(orc):
 575         CASE_OP_32_64(eqv):
 576         CASE_OP_32_64(nand):
 577         CASE_OP_32_64(nor):
 578             if (temps[args[1]].state == TCG_TEMP_CONST
 579                 && temps[args[2]].state == TCG_TEMP_CONST) {
 580                 gen_opc_buf[op_index] = op_to_movi(op);
 581                 tmp = do_constant_folding(op, temps[args[1]].val,
 582                                           temps[args[2]].val);
 583                 tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
 584                 gen_args += 2;
 585             } else {
 586                 reset_temp(args[0], nb_temps, nb_globals);
 587                 gen_args[0] = args[0];
 588                 gen_args[1] = args[1];
 589                 gen_args[2] = args[2];
 590                 gen_args += 3;
 591             }
 592             args += 3;
 593             break;
 594         CASE_OP_32_64(setcond):
 595             if (temps[args[1]].state == TCG_TEMP_CONST
 596                 && temps[args[2]].state == TCG_TEMP_CONST) {
 597                 gen_opc_buf[op_index] = op_to_movi(op);
 598                 tmp = do_constant_folding_cond(op, temps[args[1]].val,
 599                                                temps[args[2]].val, args[3]);
 600                 tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
 601                 gen_args += 2;
 602             } else {
 603                 reset_temp(args[0], nb_temps, nb_globals);
 604                 gen_args[0] = args[0];
 605                 gen_args[1] = args[1];
 606                 gen_args[2] = args[2];
 607                 gen_args[3] = args[3];
 608                 gen_args += 4;
 609             }
 610             args += 4;
 611             break;
 612         CASE_OP_32_64(brcond):
 613             if (temps[args[0]].state == TCG_TEMP_CONST
 614                 && temps[args[1]].state == TCG_TEMP_CONST) {
 615                 if (do_constant_folding_cond(op, temps[args[0]].val,
 616                                              temps[args[1]].val, args[2])) {
 617                     memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 618                     gen_opc_buf[op_index] = INDEX_op_br;
 619                     gen_args[0] = args[3];
 620                     gen_args += 1;
 621                 } else {
 622                     gen_opc_buf[op_index] = INDEX_op_nop;
 623                 }
 624             } else {
 625                 memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 626                 reset_temp(args[0], nb_temps, nb_globals);
 627                 gen_args[0] = args[0];
 628                 gen_args[1] = args[1];
 629                 gen_args[2] = args[2];
 630                 gen_args[3] = args[3];
 631                 gen_args += 4;
 632             }
 633             args += 4;
 634             break;
 635         CASE_OP_32_64(movcond):
 636             if (temps[args[1]].state == TCG_TEMP_CONST
 637                 && temps[args[2]].state == TCG_TEMP_CONST) {
 638                 tmp = do_constant_folding_cond(op, temps[args[1]].val,
 639                                                temps[args[2]].val, args[5]);
 640                 if (args[0] == args[4-tmp]
 641                     || (temps[args[4-tmp]].state == TCG_TEMP_COPY
 642                         && temps[args[4-tmp]].val == args[0])) {
 643                     gen_opc_buf[op_index] = INDEX_op_nop;
 644                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
 645                     gen_opc_buf[op_index] = op_to_movi(op);
 646                     tcg_opt_gen_movi(gen_args, args[0], temps[args[4-tmp]].val,
 647                                      nb_temps, nb_globals);
 648                     gen_args += 2;
 649                 } else {
 650                     gen_opc_buf[op_index] = op_to_mov(op);
 651                     tcg_opt_gen_mov(gen_args, args[0], args[4-tmp],
 652                                     nb_temps, nb_globals);
 653                     gen_args += 2;
 654                 }
 655             } else {
 656                 reset_temp(args[0], nb_temps, nb_globals);
 657                 gen_args[0] = args[0];
 658                 gen_args[1] = args[1];
 659                 gen_args[2] = args[2];
 660                 gen_args[3] = args[3];
 661                 gen_args[4] = args[4];
 662                 gen_args[5] = args[5];
 663                 gen_args += 6;
 664             }
 665             args += 6;
 666             break;
 667         case INDEX_op_call:
 668             nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
 669             if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) {
 670                 for (i = 0; i < nb_globals; i++) {
 671                     reset_temp(i, nb_temps, nb_globals);
 672                 }
 673             }
 674             for (i = 0; i < (args[0] >> 16); i++) {
 675                 reset_temp(args[i + 1], nb_temps, nb_globals);
 676             }
 677             i = nb_call_args + 3;
 678             while (i) {
 679                 *gen_args = *args;
 680                 args++;
 681                 gen_args++;
 682                 i--;
 683             }
 684             break;
 685         default:
 686             /* Default case: we do know nothing about operation so no
 687                propagation is done.  We trash everything if the operation
 688                is the end of a basic block, otherwise we only trash the
 689                output args.  */
 690             if (def->flags & TCG_OPF_BB_END) {
 691                 memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 692             } else {
 693                 for (i = 0; i < def->nb_oargs; i++) {
 694                     reset_temp(args[i], nb_temps, nb_globals);
 695                 }
 696             }
 697             for (i = 0; i < def->nb_args; i++) {
 698                 gen_args[i] = args[i];
 699             }
 700             args += def->nb_args;
 701             gen_args += def->nb_args;
 702             break;
 703         }
 704     }
 705
 706     return gen_args;
 707 }
 708
 709 TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
 710         TCGArg *args, TCGOpDef *tcg_op_defs)
 711 {
 712     TCGArg *res;
 713     res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
 714     return res;
 715 }