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 };
  50
  51 static struct tcg_temp_info temps[TCG_MAX_TEMPS];
  52
  53 /* Reset TEMP's state to TCG_TEMP_UNDEF.  If TEMP only had one copy, remove
  54    the copy flag from the left temp.  */
  55 static void reset_temp(TCGArg temp)
  56 {
  57     if (temps[temp].state == TCG_TEMP_COPY) {
  58         if (temps[temp].prev_copy == temps[temp].next_copy) {
  59             temps[temps[temp].next_copy].state = TCG_TEMP_UNDEF;
  60         } else {
  61             temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
  62             temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
  63         }
  64     }
  65     temps[temp].state = TCG_TEMP_UNDEF;
  66 }
  67
  68 static int op_bits(TCGOpcode op)
  69 {
  70     const TCGOpDef *def = &tcg_op_defs[op];
  71     return def->flags & TCG_OPF_64BIT ? 64 : 32;
  72 }
  73
  74 static TCGOpcode op_to_movi(TCGOpcode op)
  75 {
  76     switch (op_bits(op)) {
  77     case 32:
  78         return INDEX_op_movi_i32;
  79     case 64:
  80         return INDEX_op_movi_i64;
  81     default:
  82         fprintf(stderr, "op_to_movi: unexpected return value of "
  83                 "function op_bits.\n");
  84         tcg_abort();
  85     }
  86 }
  87
  88 static TCGArg find_better_copy(TCGContext *s, TCGArg temp)
  89 {
  90     TCGArg i;
  91
  92     /* If this is already a global, we can't do better. */
  93     if (temp < s->nb_globals) {
  94         return temp;
  95     }
  96
  97     /* Search for a global first. */
  98     for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
  99         if (i < s->nb_globals) {
 100             return i;
 101         }
 102     }
 103
 104     /* If it is a temp, search for a temp local. */
 105     if (!s->temps[temp].temp_local) {
 106         for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
 107             if (s->temps[i].temp_local) {
 108                 return i;
 109             }
 110         }
 111     }
 112
 113     /* Failure to find a better representation, return the same temp. */
 114     return temp;
 115 }
 116
 117 static bool temps_are_copies(TCGArg arg1, TCGArg arg2)
 118 {
 119     TCGArg i;
 120
 121     if (arg1 == arg2) {
 122         return true;
 123     }
 124
 125     if (temps[arg1].state != TCG_TEMP_COPY
 126         || temps[arg2].state != TCG_TEMP_COPY) {
 127         return false;
 128     }
 129
 130     for (i = temps[arg1].next_copy ; i != arg1 ; i = temps[i].next_copy) {
 131         if (i == arg2) {
 132             return true;
 133         }
 134     }
 135
 136     return false;
 137 }
 138
 139 static void tcg_opt_gen_mov(TCGContext *s, TCGArg *gen_args,
 140                             TCGArg dst, TCGArg src)
 141 {
 142         reset_temp(dst);
 143         assert(temps[src].state != TCG_TEMP_CONST);
 144
 145         if (s->temps[src].type == s->temps[dst].type) {
 146             if (temps[src].state != TCG_TEMP_COPY) {
 147                 temps[src].state = TCG_TEMP_COPY;
 148                 temps[src].next_copy = src;
 149                 temps[src].prev_copy = src;
 150             }
 151             temps[dst].state = TCG_TEMP_COPY;
 152             temps[dst].next_copy = temps[src].next_copy;
 153             temps[dst].prev_copy = src;
 154             temps[temps[dst].next_copy].prev_copy = dst;
 155             temps[src].next_copy = dst;
 156         }
 157
 158         gen_args[0] = dst;
 159         gen_args[1] = src;
 160 }
 161
 162 static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val)
 163 {
 164         reset_temp(dst);
 165         temps[dst].state = TCG_TEMP_CONST;
 166         temps[dst].val = val;
 167         gen_args[0] = dst;
 168         gen_args[1] = val;
 169 }
 170
 171 static TCGOpcode op_to_mov(TCGOpcode op)
 172 {
 173     switch (op_bits(op)) {
 174     case 32:
 175         return INDEX_op_mov_i32;
 176     case 64:
 177         return INDEX_op_mov_i64;
 178     default:
 179         fprintf(stderr, "op_to_mov: unexpected return value of "
 180                 "function op_bits.\n");
 181         tcg_abort();
 182     }
 183 }
 184
 185 static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
 186 {
 187     switch (op) {
 188     CASE_OP_32_64(add):
 189         return x + y;
 190
 191     CASE_OP_32_64(sub):
 192         return x - y;
 193
 194     CASE_OP_32_64(mul):
 195         return x * y;
 196
 197     CASE_OP_32_64(and):
 198         return x & y;
 199
 200     CASE_OP_32_64(or):
 201         return x | y;
 202
 203     CASE_OP_32_64(xor):
 204         return x ^ y;
 205
 206     case INDEX_op_shl_i32:
 207         return (uint32_t)x << (uint32_t)y;
 208
 209     case INDEX_op_shl_i64:
 210         return (uint64_t)x << (uint64_t)y;
 211
 212     case INDEX_op_shr_i32:
 213         return (uint32_t)x >> (uint32_t)y;
 214
 215     case INDEX_op_shr_i64:
 216         return (uint64_t)x >> (uint64_t)y;
 217
 218     case INDEX_op_sar_i32:
 219         return (int32_t)x >> (int32_t)y;
 220
 221     case INDEX_op_sar_i64:
 222         return (int64_t)x >> (int64_t)y;
 223
 224     case INDEX_op_rotr_i32:
 225         x = ((uint32_t)x << (32 - y)) | ((uint32_t)x >> y);
 226         return x;
 227
 228     case INDEX_op_rotr_i64:
 229         x = ((uint64_t)x << (64 - y)) | ((uint64_t)x >> y);
 230         return x;
 231
 232     case INDEX_op_rotl_i32:
 233         x = ((uint32_t)x << y) | ((uint32_t)x >> (32 - y));
 234         return x;
 235
 236     case INDEX_op_rotl_i64:
 237         x = ((uint64_t)x << y) | ((uint64_t)x >> (64 - y));
 238         return x;
 239
 240     CASE_OP_32_64(not):
 241         return ~x;
 242
 243     CASE_OP_32_64(neg):
 244         return -x;
 245
 246     CASE_OP_32_64(andc):
 247         return x & ~y;
 248
 249     CASE_OP_32_64(orc):
 250         return x | ~y;
 251
 252     CASE_OP_32_64(eqv):
 253         return ~(x ^ y);
 254
 255     CASE_OP_32_64(nand):
 256         return ~(x & y);
 257
 258     CASE_OP_32_64(nor):
 259         return ~(x | y);
 260
 261     CASE_OP_32_64(ext8s):
 262         return (int8_t)x;
 263
 264     CASE_OP_32_64(ext16s):
 265         return (int16_t)x;
 266
 267     CASE_OP_32_64(ext8u):
 268         return (uint8_t)x;
 269
 270     CASE_OP_32_64(ext16u):
 271         return (uint16_t)x;
 272
 273     case INDEX_op_ext32s_i64:
 274         return (int32_t)x;
 275
 276     case INDEX_op_ext32u_i64:
 277         return (uint32_t)x;
 278
 279     default:
 280         fprintf(stderr,
 281                 "Unrecognized operation %d in do_constant_folding.\n", op);
 282         tcg_abort();
 283     }
 284 }
 285
 286 static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
 287 {
 288     TCGArg res = do_constant_folding_2(op, x, y);
 289     if (op_bits(op) == 32) {
 290         res &= 0xffffffff;
 291     }
 292     return res;
 293 }
 294
 295 static bool do_constant_folding_cond_32(uint32_t x, uint32_t y, TCGCond c)
 296 {
 297     switch (c) {
 298     case TCG_COND_EQ:
 299         return x == y;
 300     case TCG_COND_NE:
 301         return x != y;
 302     case TCG_COND_LT:
 303         return (int32_t)x < (int32_t)y;
 304     case TCG_COND_GE:
 305         return (int32_t)x >= (int32_t)y;
 306     case TCG_COND_LE:
 307         return (int32_t)x <= (int32_t)y;
 308     case TCG_COND_GT:
 309         return (int32_t)x > (int32_t)y;
 310     case TCG_COND_LTU:
 311         return x < y;
 312     case TCG_COND_GEU:
 313         return x >= y;
 314     case TCG_COND_LEU:
 315         return x <= y;
 316     case TCG_COND_GTU:
 317         return x > y;
 318     default:
 319         tcg_abort();
 320     }
 321 }
 322
 323 static bool do_constant_folding_cond_64(uint64_t x, uint64_t y, TCGCond c)
 324 {
 325     switch (c) {
 326     case TCG_COND_EQ:
 327         return x == y;
 328     case TCG_COND_NE:
 329         return x != y;
 330     case TCG_COND_LT:
 331         return (int64_t)x < (int64_t)y;
 332     case TCG_COND_GE:
 333         return (int64_t)x >= (int64_t)y;
 334     case TCG_COND_LE:
 335         return (int64_t)x <= (int64_t)y;
 336     case TCG_COND_GT:
 337         return (int64_t)x > (int64_t)y;
 338     case TCG_COND_LTU:
 339         return x < y;
 340     case TCG_COND_GEU:
 341         return x >= y;
 342     case TCG_COND_LEU:
 343         return x <= y;
 344     case TCG_COND_GTU:
 345         return x > y;
 346     default:
 347         tcg_abort();
 348     }
 349 }
 350
 351 static bool do_constant_folding_cond_eq(TCGCond c)
 352 {
 353     switch (c) {
 354     case TCG_COND_GT:
 355     case TCG_COND_LTU:
 356     case TCG_COND_LT:
 357     case TCG_COND_GTU:
 358     case TCG_COND_NE:
 359         return 0;
 360     case TCG_COND_GE:
 361     case TCG_COND_GEU:
 362     case TCG_COND_LE:
 363     case TCG_COND_LEU:
 364     case TCG_COND_EQ:
 365         return 1;
 366     default:
 367         tcg_abort();
 368     }
 369 }
 370
 371 /* Return 2 if the condition can't be simplified, and the result
 372    of the condition (0 or 1) if it can */
 373 static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
 374                                        TCGArg y, TCGCond c)
 375 {
 376     if (temps[x].state == TCG_TEMP_CONST && temps[y].state == TCG_TEMP_CONST) {
 377         switch (op_bits(op)) {
 378         case 32:
 379             return do_constant_folding_cond_32(temps[x].val, temps[y].val, c);
 380         case 64:
 381             return do_constant_folding_cond_64(temps[x].val, temps[y].val, c);
 382         default:
 383             tcg_abort();
 384         }
 385     } else if (temps_are_copies(x, y)) {
 386         return do_constant_folding_cond_eq(c);
 387     } else if (temps[y].state == TCG_TEMP_CONST && temps[y].val == 0) {
 388         switch (c) {
 389         case TCG_COND_LTU:
 390             return 0;
 391         case TCG_COND_GEU:
 392             return 1;
 393         default:
 394             return 2;
 395         }
 396     } else {
 397         return 2;
 398     }
 399 }
 400
 401 /* Return 2 if the condition can't be simplified, and the result
 402    of the condition (0 or 1) if it can */
 403 static TCGArg do_constant_folding_cond2(TCGArg *p1, TCGArg *p2, TCGCond c)
 404 {
 405     TCGArg al = p1[0], ah = p1[1];
 406     TCGArg bl = p2[0], bh = p2[1];
 407
 408     if (temps[bl].state == TCG_TEMP_CONST
 409         && temps[bh].state == TCG_TEMP_CONST) {
 410         uint64_t b = ((uint64_t)temps[bh].val << 32) | (uint32_t)temps[bl].val;
 411
 412         if (temps[al].state == TCG_TEMP_CONST
 413             && temps[ah].state == TCG_TEMP_CONST) {
 414             uint64_t a;
 415             a = ((uint64_t)temps[ah].val << 32) | (uint32_t)temps[al].val;
 416             return do_constant_folding_cond_64(a, b, c);
 417         }
 418         if (b == 0) {
 419             switch (c) {
 420             case TCG_COND_LTU:
 421                 return 0;
 422             case TCG_COND_GEU:
 423                 return 1;
 424             default:
 425                 break;
 426             }
 427         }
 428     }
 429     if (temps_are_copies(al, bl) && temps_are_copies(ah, bh)) {
 430         return do_constant_folding_cond_eq(c);
 431     }
 432     return 2;
 433 }
 434
 435 static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2)
 436 {
 437     TCGArg a1 = *p1, a2 = *p2;
 438     int sum = 0;
 439     sum += temps[a1].state == TCG_TEMP_CONST;
 440     sum -= temps[a2].state == TCG_TEMP_CONST;
 441
 442     /* Prefer the constant in second argument, and then the form
 443        op a, a, b, which is better handled on non-RISC hosts. */
 444     if (sum > 0 || (sum == 0 && dest == a2)) {
 445         *p1 = a2;
 446         *p2 = a1;
 447         return true;
 448     }
 449     return false;
 450 }
 451
 452 static bool swap_commutative2(TCGArg *p1, TCGArg *p2)
 453 {
 454     int sum = 0;
 455     sum += temps[p1[0]].state == TCG_TEMP_CONST;
 456     sum += temps[p1[1]].state == TCG_TEMP_CONST;
 457     sum -= temps[p2[0]].state == TCG_TEMP_CONST;
 458     sum -= temps[p2[1]].state == TCG_TEMP_CONST;
 459     if (sum > 0) {
 460         TCGArg t;
 461         t = p1[0], p1[0] = p2[0], p2[0] = t;
 462         t = p1[1], p1[1] = p2[1], p2[1] = t;
 463         return true;
 464     }
 465     return false;
 466 }
 467
 468 /* Propagate constants and copies, fold constant expressions. */
 469 static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
 470                                     TCGArg *args, TCGOpDef *tcg_op_defs)
 471 {
 472     int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;
 473     TCGOpcode op;
 474     const TCGOpDef *def;
 475     TCGArg *gen_args;
 476     TCGArg tmp;
 477
 478     /* Array VALS has an element for each temp.
 479        If this temp holds a constant then its value is kept in VALS' element.
 480        If this temp is a copy of other ones then the other copies are
 481        available through the doubly linked circular list. */
 482
 483     nb_temps = s->nb_temps;
 484     nb_globals = s->nb_globals;
 485     memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 486
 487     nb_ops = tcg_opc_ptr - gen_opc_buf;
 488     gen_args = args;
 489     for (op_index = 0; op_index < nb_ops; op_index++) {
 490         op = gen_opc_buf[op_index];
 491         def = &tcg_op_defs[op];
 492         /* Do copy propagation */
 493         if (op == INDEX_op_call) {
 494             int nb_oargs = args[0] >> 16;
 495             int nb_iargs = args[0] & 0xffff;
 496             for (i = nb_oargs + 1; i < nb_oargs + nb_iargs + 1; i++) {
 497                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 498                     args[i] = find_better_copy(s, args[i]);
 499                 }
 500             }
 501         } else {
 502             for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
 503                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 504                     args[i] = find_better_copy(s, args[i]);
 505                 }
 506             }
 507         }
 508
 509         /* For commutative operations make constant second argument */
 510         switch (op) {
 511         CASE_OP_32_64(add):
 512         CASE_OP_32_64(mul):
 513         CASE_OP_32_64(and):
 514         CASE_OP_32_64(or):
 515         CASE_OP_32_64(xor):
 516         CASE_OP_32_64(eqv):
 517         CASE_OP_32_64(nand):
 518         CASE_OP_32_64(nor):
 519             swap_commutative(args[0], &args[1], &args[2]);
 520             break;
 521         CASE_OP_32_64(brcond):
 522             if (swap_commutative(-1, &args[0], &args[1])) {
 523                 args[2] = tcg_swap_cond(args[2]);
 524             }
 525             break;
 526         CASE_OP_32_64(setcond):
 527             if (swap_commutative(args[0], &args[1], &args[2])) {
 528                 args[3] = tcg_swap_cond(args[3]);
 529             }
 530             break;
 531         CASE_OP_32_64(movcond):
 532             if (swap_commutative(-1, &args[1], &args[2])) {
 533                 args[5] = tcg_swap_cond(args[5]);
 534             }
 535             /* For movcond, we canonicalize the "false" input reg to match
 536                the destination reg so that the tcg backend can implement
 537                a "move if true" operation.  */
 538             if (swap_commutative(args[0], &args[4], &args[3])) {
 539                 args[5] = tcg_invert_cond(args[5]);
 540             }
 541             break;
 542         case INDEX_op_add2_i32:
 543             swap_commutative(args[0], &args[2], &args[4]);
 544             swap_commutative(args[1], &args[3], &args[5]);
 545             break;
 546         case INDEX_op_brcond2_i32:
 547             if (swap_commutative2(&args[0], &args[2])) {
 548                 args[4] = tcg_swap_cond(args[4]);
 549             }
 550             break;
 551         case INDEX_op_setcond2_i32:
 552             if (swap_commutative2(&args[1], &args[3])) {
 553                 args[5] = tcg_swap_cond(args[5]);
 554             }
 555             break;
 556         default:
 557             break;
 558         }
 559
 560         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0" */
 561         switch (op) {
 562         CASE_OP_32_64(shl):
 563         CASE_OP_32_64(shr):
 564         CASE_OP_32_64(sar):
 565         CASE_OP_32_64(rotl):
 566         CASE_OP_32_64(rotr):
 567             if (temps[args[1]].state == TCG_TEMP_CONST
 568                 && temps[args[1]].val == 0) {
 569                 gen_opc_buf[op_index] = op_to_movi(op);
 570                 tcg_opt_gen_movi(gen_args, args[0], 0);
 571                 args += 3;
 572                 gen_args += 2;
 573                 continue;
 574             }
 575             break;
 576         default:
 577             break;
 578         }
 579
 580         /* Simplify expression for "op r, a, 0 => mov r, a" cases */
 581         switch (op) {
 582         CASE_OP_32_64(add):
 583         CASE_OP_32_64(sub):
 584         CASE_OP_32_64(shl):
 585         CASE_OP_32_64(shr):
 586         CASE_OP_32_64(sar):
 587         CASE_OP_32_64(rotl):
 588         CASE_OP_32_64(rotr):
 589         CASE_OP_32_64(or):
 590         CASE_OP_32_64(xor):
 591             if (temps[args[1]].state == TCG_TEMP_CONST) {
 592                 /* Proceed with possible constant folding. */
 593                 break;
 594             }
 595             if (temps[args[2]].state == TCG_TEMP_CONST
 596                 && temps[args[2]].val == 0) {
 597                 if (temps_are_copies(args[0], args[1])) {
 598                     gen_opc_buf[op_index] = INDEX_op_nop;
 599                 } else {
 600                     gen_opc_buf[op_index] = op_to_mov(op);
 601                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 602                     gen_args += 2;
 603                 }
 604                 args += 3;
 605                 continue;
 606             }
 607             break;
 608         default:
 609             break;
 610         }
 611
 612         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 613         switch (op) {
 614         CASE_OP_32_64(and):
 615         CASE_OP_32_64(mul):
 616             if ((temps[args[2]].state == TCG_TEMP_CONST
 617                 && temps[args[2]].val == 0)) {
 618                 gen_opc_buf[op_index] = op_to_movi(op);
 619                 tcg_opt_gen_movi(gen_args, args[0], 0);
 620                 args += 3;
 621                 gen_args += 2;
 622                 continue;
 623             }
 624             break;
 625         default:
 626             break;
 627         }
 628
 629         /* Simplify expression for "op r, a, a => mov r, a" cases */
 630         switch (op) {
 631         CASE_OP_32_64(or):
 632         CASE_OP_32_64(and):
 633             if (temps_are_copies(args[1], args[2])) {
 634                 if (temps_are_copies(args[0], args[1])) {
 635                     gen_opc_buf[op_index] = INDEX_op_nop;
 636                 } else {
 637                     gen_opc_buf[op_index] = op_to_mov(op);
 638                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 639                     gen_args += 2;
 640                 }
 641                 args += 3;
 642                 continue;
 643             }
 644             break;
 645         default:
 646             break;
 647         }
 648
 649         /* Simplify expression for "op r, a, a => movi r, 0" cases */
 650         switch (op) {
 651         CASE_OP_32_64(sub):
 652         CASE_OP_32_64(xor):
 653             if (temps_are_copies(args[1], args[2])) {
 654                 gen_opc_buf[op_index] = op_to_movi(op);
 655                 tcg_opt_gen_movi(gen_args, args[0], 0);
 656                 gen_args += 2;
 657                 args += 3;
 658                 continue;
 659             }
 660             break;
 661         default:
 662             break;
 663         }
 664
 665         /* Propagate constants through copy operations and do constant
 666            folding.  Constants will be substituted to arguments by register
 667            allocator where needed and possible.  Also detect copies. */
 668         switch (op) {
 669         CASE_OP_32_64(mov):
 670             if (temps_are_copies(args[0], args[1])) {
 671                 args += 2;
 672                 gen_opc_buf[op_index] = INDEX_op_nop;
 673                 break;
 674             }
 675             if (temps[args[1]].state != TCG_TEMP_CONST) {
 676                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 677                 gen_args += 2;
 678                 args += 2;
 679                 break;
 680             }
 681             /* Source argument is constant.  Rewrite the operation and
 682                let movi case handle it. */
 683             op = op_to_movi(op);
 684             gen_opc_buf[op_index] = op;
 685             args[1] = temps[args[1]].val;
 686             /* fallthrough */
 687         CASE_OP_32_64(movi):
 688             tcg_opt_gen_movi(gen_args, args[0], args[1]);
 689             gen_args += 2;
 690             args += 2;
 691             break;
 692
 693         CASE_OP_32_64(not):
 694         CASE_OP_32_64(neg):
 695         CASE_OP_32_64(ext8s):
 696         CASE_OP_32_64(ext8u):
 697         CASE_OP_32_64(ext16s):
 698         CASE_OP_32_64(ext16u):
 699         case INDEX_op_ext32s_i64:
 700         case INDEX_op_ext32u_i64:
 701             if (temps[args[1]].state == TCG_TEMP_CONST) {
 702                 gen_opc_buf[op_index] = op_to_movi(op);
 703                 tmp = do_constant_folding(op, temps[args[1]].val, 0);
 704                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 705                 gen_args += 2;
 706                 args += 2;
 707                 break;
 708             }
 709             goto do_default;
 710
 711         CASE_OP_32_64(add):
 712         CASE_OP_32_64(sub):
 713         CASE_OP_32_64(mul):
 714         CASE_OP_32_64(or):
 715         CASE_OP_32_64(and):
 716         CASE_OP_32_64(xor):
 717         CASE_OP_32_64(shl):
 718         CASE_OP_32_64(shr):
 719         CASE_OP_32_64(sar):
 720         CASE_OP_32_64(rotl):
 721         CASE_OP_32_64(rotr):
 722         CASE_OP_32_64(andc):
 723         CASE_OP_32_64(orc):
 724         CASE_OP_32_64(eqv):
 725         CASE_OP_32_64(nand):
 726         CASE_OP_32_64(nor):
 727             if (temps[args[1]].state == TCG_TEMP_CONST
 728                 && temps[args[2]].state == TCG_TEMP_CONST) {
 729                 gen_opc_buf[op_index] = op_to_movi(op);
 730                 tmp = do_constant_folding(op, temps[args[1]].val,
 731                                           temps[args[2]].val);
 732                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 733                 gen_args += 2;
 734                 args += 3;
 735                 break;
 736             }
 737             goto do_default;
 738
 739         CASE_OP_32_64(deposit):
 740             if (temps[args[1]].state == TCG_TEMP_CONST
 741                 && temps[args[2]].state == TCG_TEMP_CONST) {
 742                 gen_opc_buf[op_index] = op_to_movi(op);
 743                 tmp = ((1ull << args[4]) - 1);
 744                 tmp = (temps[args[1]].val & ~(tmp << args[3]))
 745                       | ((temps[args[2]].val & tmp) << args[3]);
 746                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 747                 gen_args += 2;
 748                 args += 5;
 749                 break;
 750             }
 751             goto do_default;
 752
 753         CASE_OP_32_64(setcond):
 754             tmp = do_constant_folding_cond(op, args[1], args[2], args[3]);
 755             if (tmp != 2) {
 756                 gen_opc_buf[op_index] = op_to_movi(op);
 757                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 758                 gen_args += 2;
 759                 args += 4;
 760                 break;
 761             }
 762             goto do_default;
 763
 764         CASE_OP_32_64(brcond):
 765             tmp = do_constant_folding_cond(op, args[0], args[1], args[2]);
 766             if (tmp != 2) {
 767                 if (tmp) {
 768                     memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 769                     gen_opc_buf[op_index] = INDEX_op_br;
 770                     gen_args[0] = args[3];
 771                     gen_args += 1;
 772                 } else {
 773                     gen_opc_buf[op_index] = INDEX_op_nop;
 774                 }
 775                 args += 4;
 776                 break;
 777             }
 778             goto do_default;
 779
 780         CASE_OP_32_64(movcond):
 781             tmp = do_constant_folding_cond(op, args[1], args[2], args[5]);
 782             if (tmp != 2) {
 783                 if (temps_are_copies(args[0], args[4-tmp])) {
 784                     gen_opc_buf[op_index] = INDEX_op_nop;
 785                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
 786                     gen_opc_buf[op_index] = op_to_movi(op);
 787                     tcg_opt_gen_movi(gen_args, args[0], temps[args[4-tmp]].val);
 788                     gen_args += 2;
 789                 } else {
 790                     gen_opc_buf[op_index] = op_to_mov(op);
 791                     tcg_opt_gen_mov(s, gen_args, args[0], args[4-tmp]);
 792                     gen_args += 2;
 793                 }
 794                 args += 6;
 795                 break;
 796             }
 797             goto do_default;
 798
 799         case INDEX_op_brcond2_i32:
 800             tmp = do_constant_folding_cond2(&args[0], &args[2], args[4]);
 801             if (tmp != 2) {
 802                 if (tmp) {
 803                     memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 804                     gen_opc_buf[op_index] = INDEX_op_br;
 805                     gen_args[0] = args[5];
 806                     gen_args += 1;
 807                 } else {
 808                     gen_opc_buf[op_index] = INDEX_op_nop;
 809                 }
 810             } else if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
 811                        && temps[args[2]].state == TCG_TEMP_CONST
 812                        && temps[args[3]].state == TCG_TEMP_CONST
 813                        && temps[args[2]].val == 0
 814                        && temps[args[3]].val == 0) {
 815                 /* Simplify LT/GE comparisons vs zero to a single compare
 816                    vs the high word of the input.  */
 817                 memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 818                 gen_opc_buf[op_index] = INDEX_op_brcond_i32;
 819                 gen_args[0] = args[1];
 820                 gen_args[1] = args[3];
 821                 gen_args[2] = args[4];
 822                 gen_args[3] = args[5];
 823                 gen_args += 4;
 824             } else {
 825                 goto do_default;
 826             }
 827             args += 6;
 828             break;
 829
 830         case INDEX_op_setcond2_i32:
 831             tmp = do_constant_folding_cond2(&args[1], &args[3], args[5]);
 832             if (tmp != 2) {
 833                 gen_opc_buf[op_index] = INDEX_op_movi_i32;
 834                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 835                 gen_args += 2;
 836             } else if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
 837                        && temps[args[3]].state == TCG_TEMP_CONST
 838                        && temps[args[4]].state == TCG_TEMP_CONST
 839                        && temps[args[3]].val == 0
 840                        && temps[args[4]].val == 0) {
 841                 /* Simplify LT/GE comparisons vs zero to a single compare
 842                    vs the high word of the input.  */
 843                 gen_opc_buf[op_index] = INDEX_op_setcond_i32;
 844                 gen_args[0] = args[0];
 845                 gen_args[1] = args[2];
 846                 gen_args[2] = args[4];
 847                 gen_args[3] = args[5];
 848                 gen_args += 4;
 849             } else {
 850                 goto do_default;
 851             }
 852             args += 6;
 853             break;
 854
 855         case INDEX_op_call:
 856             nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
 857             if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) {
 858                 for (i = 0; i < nb_globals; i++) {
 859                     reset_temp(i);
 860                 }
 861             }
 862             for (i = 0; i < (args[0] >> 16); i++) {
 863                 reset_temp(args[i + 1]);
 864             }
 865             i = nb_call_args + 3;
 866             while (i) {
 867                 *gen_args = *args;
 868                 args++;
 869                 gen_args++;
 870                 i--;
 871             }
 872             break;
 873
 874         default:
 875         do_default:
 876             /* Default case: we know nothing about operation (or were unable
 877                to compute the operation result) so no propagation is done.
 878                We trash everything if the operation is the end of a basic
 879                block, otherwise we only trash the output args.  */
 880             if (def->flags & TCG_OPF_BB_END) {
 881                 memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
 882             } else {
 883                 for (i = 0; i < def->nb_oargs; i++) {
 884                     reset_temp(args[i]);
 885                 }
 886             }
 887             for (i = 0; i < def->nb_args; i++) {
 888                 gen_args[i] = args[i];
 889             }
 890             args += def->nb_args;
 891             gen_args += def->nb_args;
 892             break;
 893         }
 894     }
 895
 896     return gen_args;
 897 }
 898
 899 TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
 900         TCGArg *args, TCGOpDef *tcg_op_defs)
 901 {
 902     TCGArg *res;
 903     res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
 904     return res;
 905 }