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_movi(TCGOpcode op)
  87 {
  88     switch (op_bits(op)) {
  89     case 32:
  90         return INDEX_op_movi_i32;
  91     case 64:
  92         return INDEX_op_movi_i64;
  93     default:
  94         fprintf(stderr, "op_to_movi: unexpected return value of "
  95                 "function op_bits.\n");
  96         tcg_abort();
  97     }
  98 }
  99
 100 static TCGArg find_better_copy(TCGContext *s, TCGArg temp)
 101 {
 102     TCGArg i;
 103
 104     /* If this is already a global, we can't do better. */
 105     if (temp < s->nb_globals) {
 106         return temp;
 107     }
 108
 109     /* Search for a global first. */
 110     for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
 111         if (i < s->nb_globals) {
 112             return i;
 113         }
 114     }
 115
 116     /* If it is a temp, search for a temp local. */
 117     if (!s->temps[temp].temp_local) {
 118         for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {
 119             if (s->temps[i].temp_local) {
 120                 return i;
 121             }
 122         }
 123     }
 124
 125     /* Failure to find a better representation, return the same temp. */
 126     return temp;
 127 }
 128
 129 static bool temps_are_copies(TCGArg arg1, TCGArg arg2)
 130 {
 131     TCGArg i;
 132
 133     if (arg1 == arg2) {
 134         return true;
 135     }
 136
 137     if (temps[arg1].state != TCG_TEMP_COPY
 138         || temps[arg2].state != TCG_TEMP_COPY) {
 139         return false;
 140     }
 141
 142     for (i = temps[arg1].next_copy ; i != arg1 ; i = temps[i].next_copy) {
 143         if (i == arg2) {
 144             return true;
 145         }
 146     }
 147
 148     return false;
 149 }
 150
 151 static void tcg_opt_gen_mov(TCGContext *s, TCGArg *gen_args,
 152                             TCGArg dst, TCGArg src)
 153 {
 154     reset_temp(dst);
 155     temps[dst].mask = temps[src].mask;
 156     assert(temps[src].state != TCG_TEMP_CONST);
 157
 158     if (s->temps[src].type == s->temps[dst].type) {
 159         if (temps[src].state != TCG_TEMP_COPY) {
 160             temps[src].state = TCG_TEMP_COPY;
 161             temps[src].next_copy = src;
 162             temps[src].prev_copy = src;
 163         }
 164         temps[dst].state = TCG_TEMP_COPY;
 165         temps[dst].next_copy = temps[src].next_copy;
 166         temps[dst].prev_copy = src;
 167         temps[temps[dst].next_copy].prev_copy = dst;
 168         temps[src].next_copy = dst;
 169     }
 170
 171     gen_args[0] = dst;
 172     gen_args[1] = src;
 173 }
 174
 175 static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val)
 176 {
 177     reset_temp(dst);
 178     temps[dst].state = TCG_TEMP_CONST;
 179     temps[dst].val = val;
 180     temps[dst].mask = val;
 181     gen_args[0] = dst;
 182     gen_args[1] = val;
 183 }
 184
 185 static TCGOpcode op_to_mov(TCGOpcode op)
 186 {
 187     switch (op_bits(op)) {
 188     case 32:
 189         return INDEX_op_mov_i32;
 190     case 64:
 191         return INDEX_op_mov_i64;
 192     default:
 193         fprintf(stderr, "op_to_mov: unexpected return value of "
 194                 "function op_bits.\n");
 195         tcg_abort();
 196     }
 197 }
 198
 199 static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
 200 {
 201     switch (op) {
 202     CASE_OP_32_64(add):
 203         return x + y;
 204
 205     CASE_OP_32_64(sub):
 206         return x - y;
 207
 208     CASE_OP_32_64(mul):
 209         return x * y;
 210
 211     CASE_OP_32_64(and):
 212         return x & y;
 213
 214     CASE_OP_32_64(or):
 215         return x | y;
 216
 217     CASE_OP_32_64(xor):
 218         return x ^ y;
 219
 220     case INDEX_op_shl_i32:
 221         return (uint32_t)x << (uint32_t)y;
 222
 223     case INDEX_op_shl_i64:
 224         return (uint64_t)x << (uint64_t)y;
 225
 226     case INDEX_op_shr_i32:
 227         return (uint32_t)x >> (uint32_t)y;
 228
 229     case INDEX_op_shr_i64:
 230         return (uint64_t)x >> (uint64_t)y;
 231
 232     case INDEX_op_sar_i32:
 233         return (int32_t)x >> (int32_t)y;
 234
 235     case INDEX_op_sar_i64:
 236         return (int64_t)x >> (int64_t)y;
 237
 238     case INDEX_op_rotr_i32:
 239         x = ((uint32_t)x << (32 - y)) | ((uint32_t)x >> y);
 240         return x;
 241
 242     case INDEX_op_rotr_i64:
 243         x = ((uint64_t)x << (64 - y)) | ((uint64_t)x >> y);
 244         return x;
 245
 246     case INDEX_op_rotl_i32:
 247         x = ((uint32_t)x << y) | ((uint32_t)x >> (32 - y));
 248         return x;
 249
 250     case INDEX_op_rotl_i64:
 251         x = ((uint64_t)x << y) | ((uint64_t)x >> (64 - y));
 252         return x;
 253
 254     CASE_OP_32_64(not):
 255         return ~x;
 256
 257     CASE_OP_32_64(neg):
 258         return -x;
 259
 260     CASE_OP_32_64(andc):
 261         return x & ~y;
 262
 263     CASE_OP_32_64(orc):
 264         return x | ~y;
 265
 266     CASE_OP_32_64(eqv):
 267         return ~(x ^ y);
 268
 269     CASE_OP_32_64(nand):
 270         return ~(x & y);
 271
 272     CASE_OP_32_64(nor):
 273         return ~(x | y);
 274
 275     CASE_OP_32_64(ext8s):
 276         return (int8_t)x;
 277
 278     CASE_OP_32_64(ext16s):
 279         return (int16_t)x;
 280
 281     CASE_OP_32_64(ext8u):
 282         return (uint8_t)x;
 283
 284     CASE_OP_32_64(ext16u):
 285         return (uint16_t)x;
 286
 287     case INDEX_op_ext32s_i64:
 288         return (int32_t)x;
 289
 290     case INDEX_op_ext32u_i64:
 291         return (uint32_t)x;
 292
 293     default:
 294         fprintf(stderr,
 295                 "Unrecognized operation %d in do_constant_folding.\n", op);
 296         tcg_abort();
 297     }
 298 }
 299
 300 static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
 301 {
 302     TCGArg res = do_constant_folding_2(op, x, y);
 303     if (op_bits(op) == 32) {
 304         res &= 0xffffffff;
 305     }
 306     return res;
 307 }
 308
 309 static bool do_constant_folding_cond_32(uint32_t x, uint32_t y, TCGCond c)
 310 {
 311     switch (c) {
 312     case TCG_COND_EQ:
 313         return x == y;
 314     case TCG_COND_NE:
 315         return x != y;
 316     case TCG_COND_LT:
 317         return (int32_t)x < (int32_t)y;
 318     case TCG_COND_GE:
 319         return (int32_t)x >= (int32_t)y;
 320     case TCG_COND_LE:
 321         return (int32_t)x <= (int32_t)y;
 322     case TCG_COND_GT:
 323         return (int32_t)x > (int32_t)y;
 324     case TCG_COND_LTU:
 325         return x < y;
 326     case TCG_COND_GEU:
 327         return x >= y;
 328     case TCG_COND_LEU:
 329         return x <= y;
 330     case TCG_COND_GTU:
 331         return x > y;
 332     default:
 333         tcg_abort();
 334     }
 335 }
 336
 337 static bool do_constant_folding_cond_64(uint64_t x, uint64_t y, TCGCond c)
 338 {
 339     switch (c) {
 340     case TCG_COND_EQ:
 341         return x == y;
 342     case TCG_COND_NE:
 343         return x != y;
 344     case TCG_COND_LT:
 345         return (int64_t)x < (int64_t)y;
 346     case TCG_COND_GE:
 347         return (int64_t)x >= (int64_t)y;
 348     case TCG_COND_LE:
 349         return (int64_t)x <= (int64_t)y;
 350     case TCG_COND_GT:
 351         return (int64_t)x > (int64_t)y;
 352     case TCG_COND_LTU:
 353         return x < y;
 354     case TCG_COND_GEU:
 355         return x >= y;
 356     case TCG_COND_LEU:
 357         return x <= y;
 358     case TCG_COND_GTU:
 359         return x > y;
 360     default:
 361         tcg_abort();
 362     }
 363 }
 364
 365 static bool do_constant_folding_cond_eq(TCGCond c)
 366 {
 367     switch (c) {
 368     case TCG_COND_GT:
 369     case TCG_COND_LTU:
 370     case TCG_COND_LT:
 371     case TCG_COND_GTU:
 372     case TCG_COND_NE:
 373         return 0;
 374     case TCG_COND_GE:
 375     case TCG_COND_GEU:
 376     case TCG_COND_LE:
 377     case TCG_COND_LEU:
 378     case TCG_COND_EQ:
 379         return 1;
 380     default:
 381         tcg_abort();
 382     }
 383 }
 384
 385 /* Return 2 if the condition can't be simplified, and the result
 386    of the condition (0 or 1) if it can */
 387 static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
 388                                        TCGArg y, TCGCond c)
 389 {
 390     if (temps[x].state == TCG_TEMP_CONST && temps[y].state == TCG_TEMP_CONST) {
 391         switch (op_bits(op)) {
 392         case 32:
 393             return do_constant_folding_cond_32(temps[x].val, temps[y].val, c);
 394         case 64:
 395             return do_constant_folding_cond_64(temps[x].val, temps[y].val, c);
 396         default:
 397             tcg_abort();
 398         }
 399     } else if (temps_are_copies(x, y)) {
 400         return do_constant_folding_cond_eq(c);
 401     } else if (temps[y].state == TCG_TEMP_CONST && temps[y].val == 0) {
 402         switch (c) {
 403         case TCG_COND_LTU:
 404             return 0;
 405         case TCG_COND_GEU:
 406             return 1;
 407         default:
 408             return 2;
 409         }
 410     } else {
 411         return 2;
 412     }
 413 }
 414
 415 /* Return 2 if the condition can't be simplified, and the result
 416    of the condition (0 or 1) if it can */
 417 static TCGArg do_constant_folding_cond2(TCGArg *p1, TCGArg *p2, TCGCond c)
 418 {
 419     TCGArg al = p1[0], ah = p1[1];
 420     TCGArg bl = p2[0], bh = p2[1];
 421
 422     if (temps[bl].state == TCG_TEMP_CONST
 423         && temps[bh].state == TCG_TEMP_CONST) {
 424         uint64_t b = ((uint64_t)temps[bh].val << 32) | (uint32_t)temps[bl].val;
 425
 426         if (temps[al].state == TCG_TEMP_CONST
 427             && temps[ah].state == TCG_TEMP_CONST) {
 428             uint64_t a;
 429             a = ((uint64_t)temps[ah].val << 32) | (uint32_t)temps[al].val;
 430             return do_constant_folding_cond_64(a, b, c);
 431         }
 432         if (b == 0) {
 433             switch (c) {
 434             case TCG_COND_LTU:
 435                 return 0;
 436             case TCG_COND_GEU:
 437                 return 1;
 438             default:
 439                 break;
 440             }
 441         }
 442     }
 443     if (temps_are_copies(al, bl) && temps_are_copies(ah, bh)) {
 444         return do_constant_folding_cond_eq(c);
 445     }
 446     return 2;
 447 }
 448
 449 static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2)
 450 {
 451     TCGArg a1 = *p1, a2 = *p2;
 452     int sum = 0;
 453     sum += temps[a1].state == TCG_TEMP_CONST;
 454     sum -= temps[a2].state == TCG_TEMP_CONST;
 455
 456     /* Prefer the constant in second argument, and then the form
 457        op a, a, b, which is better handled on non-RISC hosts. */
 458     if (sum > 0 || (sum == 0 && dest == a2)) {
 459         *p1 = a2;
 460         *p2 = a1;
 461         return true;
 462     }
 463     return false;
 464 }
 465
 466 static bool swap_commutative2(TCGArg *p1, TCGArg *p2)
 467 {
 468     int sum = 0;
 469     sum += temps[p1[0]].state == TCG_TEMP_CONST;
 470     sum += temps[p1[1]].state == TCG_TEMP_CONST;
 471     sum -= temps[p2[0]].state == TCG_TEMP_CONST;
 472     sum -= temps[p2[1]].state == TCG_TEMP_CONST;
 473     if (sum > 0) {
 474         TCGArg t;
 475         t = p1[0], p1[0] = p2[0], p2[0] = t;
 476         t = p1[1], p1[1] = p2[1], p2[1] = t;
 477         return true;
 478     }
 479     return false;
 480 }
 481
 482 /* Propagate constants and copies, fold constant expressions. */
 483 static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
 484                                     TCGArg *args, TCGOpDef *tcg_op_defs)
 485 {
 486     int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;
 487     tcg_target_ulong mask, affected;
 488     TCGOpcode op;
 489     const TCGOpDef *def;
 490     TCGArg *gen_args;
 491     TCGArg tmp;
 492
 493     /* Array VALS has an element for each temp.
 494        If this temp holds a constant then its value is kept in VALS' element.
 495        If this temp is a copy of other ones then the other copies are
 496        available through the doubly linked circular list. */
 497
 498     nb_temps = s->nb_temps;
 499     nb_globals = s->nb_globals;
 500     reset_all_temps(nb_temps);
 501
 502     nb_ops = tcg_opc_ptr - s->gen_opc_buf;
 503     gen_args = args;
 504     for (op_index = 0; op_index < nb_ops; op_index++) {
 505         op = s->gen_opc_buf[op_index];
 506         def = &tcg_op_defs[op];
 507         /* Do copy propagation */
 508         if (op == INDEX_op_call) {
 509             int nb_oargs = args[0] >> 16;
 510             int nb_iargs = args[0] & 0xffff;
 511             for (i = nb_oargs + 1; i < nb_oargs + nb_iargs + 1; i++) {
 512                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 513                     args[i] = find_better_copy(s, args[i]);
 514                 }
 515             }
 516         } else {
 517             for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
 518                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 519                     args[i] = find_better_copy(s, args[i]);
 520                 }
 521             }
 522         }
 523
 524         /* For commutative operations make constant second argument */
 525         switch (op) {
 526         CASE_OP_32_64(add):
 527         CASE_OP_32_64(mul):
 528         CASE_OP_32_64(and):
 529         CASE_OP_32_64(or):
 530         CASE_OP_32_64(xor):
 531         CASE_OP_32_64(eqv):
 532         CASE_OP_32_64(nand):
 533         CASE_OP_32_64(nor):
 534             swap_commutative(args[0], &args[1], &args[2]);
 535             break;
 536         CASE_OP_32_64(brcond):
 537             if (swap_commutative(-1, &args[0], &args[1])) {
 538                 args[2] = tcg_swap_cond(args[2]);
 539             }
 540             break;
 541         CASE_OP_32_64(setcond):
 542             if (swap_commutative(args[0], &args[1], &args[2])) {
 543                 args[3] = tcg_swap_cond(args[3]);
 544             }
 545             break;
 546         CASE_OP_32_64(movcond):
 547             if (swap_commutative(-1, &args[1], &args[2])) {
 548                 args[5] = tcg_swap_cond(args[5]);
 549             }
 550             /* For movcond, we canonicalize the "false" input reg to match
 551                the destination reg so that the tcg backend can implement
 552                a "move if true" operation.  */
 553             if (swap_commutative(args[0], &args[4], &args[3])) {
 554                 args[5] = tcg_invert_cond(args[5]);
 555             }
 556             break;
 557         CASE_OP_32_64(add2):
 558             swap_commutative(args[0], &args[2], &args[4]);
 559             swap_commutative(args[1], &args[3], &args[5]);
 560             break;
 561         CASE_OP_32_64(mulu2):
 562         CASE_OP_32_64(muls2):
 563             swap_commutative(args[0], &args[2], &args[3]);
 564             break;
 565         case INDEX_op_brcond2_i32:
 566             if (swap_commutative2(&args[0], &args[2])) {
 567                 args[4] = tcg_swap_cond(args[4]);
 568             }
 569             break;
 570         case INDEX_op_setcond2_i32:
 571             if (swap_commutative2(&args[1], &args[3])) {
 572                 args[5] = tcg_swap_cond(args[5]);
 573             }
 574             break;
 575         default:
 576             break;
 577         }
 578
 579         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0" */
 580         switch (op) {
 581         CASE_OP_32_64(shl):
 582         CASE_OP_32_64(shr):
 583         CASE_OP_32_64(sar):
 584         CASE_OP_32_64(rotl):
 585         CASE_OP_32_64(rotr):
 586             if (temps[args[1]].state == TCG_TEMP_CONST
 587                 && temps[args[1]].val == 0) {
 588                 s->gen_opc_buf[op_index] = op_to_movi(op);
 589                 tcg_opt_gen_movi(gen_args, args[0], 0);
 590                 args += 3;
 591                 gen_args += 2;
 592                 continue;
 593             }
 594             break;
 595         default:
 596             break;
 597         }
 598
 599         /* Simplify expression for "op r, a, 0 => mov r, a" cases */
 600         switch (op) {
 601         CASE_OP_32_64(add):
 602         CASE_OP_32_64(sub):
 603         CASE_OP_32_64(shl):
 604         CASE_OP_32_64(shr):
 605         CASE_OP_32_64(sar):
 606         CASE_OP_32_64(rotl):
 607         CASE_OP_32_64(rotr):
 608         CASE_OP_32_64(or):
 609         CASE_OP_32_64(xor):
 610             if (temps[args[1]].state == TCG_TEMP_CONST) {
 611                 /* Proceed with possible constant folding. */
 612                 break;
 613             }
 614             if (temps[args[2]].state == TCG_TEMP_CONST
 615                 && temps[args[2]].val == 0) {
 616                 if (temps_are_copies(args[0], args[1])) {
 617                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 618                 } else {
 619                     s->gen_opc_buf[op_index] = op_to_mov(op);
 620                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 621                     gen_args += 2;
 622                 }
 623                 args += 3;
 624                 continue;
 625             }
 626             break;
 627         default:
 628             break;
 629         }
 630
 631         /* Simplify using known-zero bits */
 632         mask = -1;
 633         affected = -1;
 634         switch (op) {
 635         CASE_OP_32_64(ext8s):
 636             if ((temps[args[1]].mask & 0x80) != 0) {
 637                 break;
 638             }
 639         CASE_OP_32_64(ext8u):
 640             mask = 0xff;
 641             goto and_const;
 642         CASE_OP_32_64(ext16s):
 643             if ((temps[args[1]].mask & 0x8000) != 0) {
 644                 break;
 645             }
 646         CASE_OP_32_64(ext16u):
 647             mask = 0xffff;
 648             goto and_const;
 649         case INDEX_op_ext32s_i64:
 650             if ((temps[args[1]].mask & 0x80000000) != 0) {
 651                 break;
 652             }
 653         case INDEX_op_ext32u_i64:
 654             mask = 0xffffffffU;
 655             goto and_const;
 656
 657         CASE_OP_32_64(and):
 658             mask = temps[args[2]].mask;
 659             if (temps[args[2]].state == TCG_TEMP_CONST) {
 660         and_const:
 661                 affected = temps[args[1]].mask & ~mask;
 662             }
 663             mask = temps[args[1]].mask & mask;
 664             break;
 665
 666         CASE_OP_32_64(sar):
 667             if (temps[args[2]].state == TCG_TEMP_CONST) {
 668                 mask = ((tcg_target_long)temps[args[1]].mask
 669                         >> temps[args[2]].val);
 670             }
 671             break;
 672
 673         CASE_OP_32_64(shr):
 674             if (temps[args[2]].state == TCG_TEMP_CONST) {
 675                 mask = temps[args[1]].mask >> temps[args[2]].val;
 676             }
 677             break;
 678
 679         CASE_OP_32_64(shl):
 680             if (temps[args[2]].state == TCG_TEMP_CONST) {
 681                 mask = temps[args[1]].mask << temps[args[2]].val;
 682             }
 683             break;
 684
 685         CASE_OP_32_64(neg):
 686             /* Set to 1 all bits to the left of the rightmost.  */
 687             mask = -(temps[args[1]].mask & -temps[args[1]].mask);
 688             break;
 689
 690         CASE_OP_32_64(deposit):
 691             tmp = ((1ull << args[4]) - 1);
 692             mask = ((temps[args[1]].mask & ~(tmp << args[3]))
 693                     | ((temps[args[2]].mask & tmp) << args[3]));
 694             break;
 695
 696         CASE_OP_32_64(or):
 697         CASE_OP_32_64(xor):
 698             mask = temps[args[1]].mask | temps[args[2]].mask;
 699             break;
 700
 701         CASE_OP_32_64(setcond):
 702             mask = 1;
 703             break;
 704
 705         CASE_OP_32_64(movcond):
 706             mask = temps[args[3]].mask | temps[args[4]].mask;
 707             break;
 708
 709         default:
 710             break;
 711         }
 712
 713         if (mask == 0) {
 714             assert(def->nb_oargs == 1);
 715             s->gen_opc_buf[op_index] = op_to_movi(op);
 716             tcg_opt_gen_movi(gen_args, args[0], 0);
 717             args += def->nb_oargs + def->nb_iargs + def->nb_cargs;
 718             gen_args += 2;
 719             continue;
 720         }
 721         if (affected == 0) {
 722             assert(def->nb_oargs == 1);
 723             if (temps_are_copies(args[0], args[1])) {
 724                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 725             } else if (temps[args[1]].state != TCG_TEMP_CONST) {
 726                 s->gen_opc_buf[op_index] = op_to_mov(op);
 727                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 728                 gen_args += 2;
 729             } else {
 730                 s->gen_opc_buf[op_index] = op_to_movi(op);
 731                 tcg_opt_gen_movi(gen_args, args[0], temps[args[1]].val);
 732                 gen_args += 2;
 733             }
 734             args += def->nb_iargs + 1;
 735             continue;
 736         }
 737
 738         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 739         switch (op) {
 740         CASE_OP_32_64(and):
 741         CASE_OP_32_64(mul):
 742             if ((temps[args[2]].state == TCG_TEMP_CONST
 743                 && temps[args[2]].val == 0)) {
 744                 s->gen_opc_buf[op_index] = op_to_movi(op);
 745                 tcg_opt_gen_movi(gen_args, args[0], 0);
 746                 args += 3;
 747                 gen_args += 2;
 748                 continue;
 749             }
 750             break;
 751         default:
 752             break;
 753         }
 754
 755         /* Simplify expression for "op r, a, a => mov r, a" cases */
 756         switch (op) {
 757         CASE_OP_32_64(or):
 758         CASE_OP_32_64(and):
 759             if (temps_are_copies(args[1], args[2])) {
 760                 if (temps_are_copies(args[0], args[1])) {
 761                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 762                 } else {
 763                     s->gen_opc_buf[op_index] = op_to_mov(op);
 764                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 765                     gen_args += 2;
 766                 }
 767                 args += 3;
 768                 continue;
 769             }
 770             break;
 771         default:
 772             break;
 773         }
 774
 775         /* Simplify expression for "op r, a, a => movi r, 0" cases */
 776         switch (op) {
 777         CASE_OP_32_64(sub):
 778         CASE_OP_32_64(xor):
 779             if (temps_are_copies(args[1], args[2])) {
 780                 s->gen_opc_buf[op_index] = op_to_movi(op);
 781                 tcg_opt_gen_movi(gen_args, args[0], 0);
 782                 gen_args += 2;
 783                 args += 3;
 784                 continue;
 785             }
 786             break;
 787         default:
 788             break;
 789         }
 790
 791         /* Propagate constants through copy operations and do constant
 792            folding.  Constants will be substituted to arguments by register
 793            allocator where needed and possible.  Also detect copies. */
 794         switch (op) {
 795         CASE_OP_32_64(mov):
 796             if (temps_are_copies(args[0], args[1])) {
 797                 args += 2;
 798                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 799                 break;
 800             }
 801             if (temps[args[1]].state != TCG_TEMP_CONST) {
 802                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 803                 gen_args += 2;
 804                 args += 2;
 805                 break;
 806             }
 807             /* Source argument is constant.  Rewrite the operation and
 808                let movi case handle it. */
 809             op = op_to_movi(op);
 810             s->gen_opc_buf[op_index] = op;
 811             args[1] = temps[args[1]].val;
 812             /* fallthrough */
 813         CASE_OP_32_64(movi):
 814             tcg_opt_gen_movi(gen_args, args[0], args[1]);
 815             gen_args += 2;
 816             args += 2;
 817             break;
 818
 819         CASE_OP_32_64(not):
 820         CASE_OP_32_64(neg):
 821         CASE_OP_32_64(ext8s):
 822         CASE_OP_32_64(ext8u):
 823         CASE_OP_32_64(ext16s):
 824         CASE_OP_32_64(ext16u):
 825         case INDEX_op_ext32s_i64:
 826         case INDEX_op_ext32u_i64:
 827             if (temps[args[1]].state == TCG_TEMP_CONST) {
 828                 s->gen_opc_buf[op_index] = op_to_movi(op);
 829                 tmp = do_constant_folding(op, temps[args[1]].val, 0);
 830                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 831                 gen_args += 2;
 832                 args += 2;
 833                 break;
 834             }
 835             goto do_default;
 836
 837         CASE_OP_32_64(add):
 838         CASE_OP_32_64(sub):
 839         CASE_OP_32_64(mul):
 840         CASE_OP_32_64(or):
 841         CASE_OP_32_64(and):
 842         CASE_OP_32_64(xor):
 843         CASE_OP_32_64(shl):
 844         CASE_OP_32_64(shr):
 845         CASE_OP_32_64(sar):
 846         CASE_OP_32_64(rotl):
 847         CASE_OP_32_64(rotr):
 848         CASE_OP_32_64(andc):
 849         CASE_OP_32_64(orc):
 850         CASE_OP_32_64(eqv):
 851         CASE_OP_32_64(nand):
 852         CASE_OP_32_64(nor):
 853             if (temps[args[1]].state == TCG_TEMP_CONST
 854                 && temps[args[2]].state == TCG_TEMP_CONST) {
 855                 s->gen_opc_buf[op_index] = op_to_movi(op);
 856                 tmp = do_constant_folding(op, temps[args[1]].val,
 857                                           temps[args[2]].val);
 858                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 859                 gen_args += 2;
 860                 args += 3;
 861                 break;
 862             }
 863             goto do_default;
 864
 865         CASE_OP_32_64(deposit):
 866             if (temps[args[1]].state == TCG_TEMP_CONST
 867                 && temps[args[2]].state == TCG_TEMP_CONST) {
 868                 s->gen_opc_buf[op_index] = op_to_movi(op);
 869                 tmp = ((1ull << args[4]) - 1);
 870                 tmp = (temps[args[1]].val & ~(tmp << args[3]))
 871                       | ((temps[args[2]].val & tmp) << args[3]);
 872                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 873                 gen_args += 2;
 874                 args += 5;
 875                 break;
 876             }
 877             goto do_default;
 878
 879         CASE_OP_32_64(setcond):
 880             tmp = do_constant_folding_cond(op, args[1], args[2], args[3]);
 881             if (tmp != 2) {
 882                 s->gen_opc_buf[op_index] = op_to_movi(op);
 883                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 884                 gen_args += 2;
 885                 args += 4;
 886                 break;
 887             }
 888             goto do_default;
 889
 890         CASE_OP_32_64(brcond):
 891             tmp = do_constant_folding_cond(op, args[0], args[1], args[2]);
 892             if (tmp != 2) {
 893                 if (tmp) {
 894                     reset_all_temps(nb_temps);
 895                     s->gen_opc_buf[op_index] = INDEX_op_br;
 896                     gen_args[0] = args[3];
 897                     gen_args += 1;
 898                 } else {
 899                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 900                 }
 901                 args += 4;
 902                 break;
 903             }
 904             goto do_default;
 905
 906         CASE_OP_32_64(movcond):
 907             tmp = do_constant_folding_cond(op, args[1], args[2], args[5]);
 908             if (tmp != 2) {
 909                 if (temps_are_copies(args[0], args[4-tmp])) {
 910                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 911                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
 912                     s->gen_opc_buf[op_index] = op_to_movi(op);
 913                     tcg_opt_gen_movi(gen_args, args[0], temps[args[4-tmp]].val);
 914                     gen_args += 2;
 915                 } else {
 916                     s->gen_opc_buf[op_index] = op_to_mov(op);
 917                     tcg_opt_gen_mov(s, gen_args, args[0], args[4-tmp]);
 918                     gen_args += 2;
 919                 }
 920                 args += 6;
 921                 break;
 922             }
 923             goto do_default;
 924
 925         case INDEX_op_add2_i32:
 926         case INDEX_op_sub2_i32:
 927             if (temps[args[2]].state == TCG_TEMP_CONST
 928                 && temps[args[3]].state == TCG_TEMP_CONST
 929                 && temps[args[4]].state == TCG_TEMP_CONST
 930                 && temps[args[5]].state == TCG_TEMP_CONST) {
 931                 uint32_t al = temps[args[2]].val;
 932                 uint32_t ah = temps[args[3]].val;
 933                 uint32_t bl = temps[args[4]].val;
 934                 uint32_t bh = temps[args[5]].val;
 935                 uint64_t a = ((uint64_t)ah << 32) | al;
 936                 uint64_t b = ((uint64_t)bh << 32) | bl;
 937                 TCGArg rl, rh;
 938
 939                 if (op == INDEX_op_add2_i32) {
 940                     a += b;
 941                 } else {
 942                     a -= b;
 943                 }
 944
 945                 /* We emit the extra nop when we emit the add2/sub2.  */
 946                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
 947
 948                 rl = args[0];
 949                 rh = args[1];
 950                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
 951                 s->gen_opc_buf[++op_index] = INDEX_op_movi_i32;
 952                 tcg_opt_gen_movi(&gen_args[0], rl, (uint32_t)a);
 953                 tcg_opt_gen_movi(&gen_args[2], rh, (uint32_t)(a >> 32));
 954                 gen_args += 4;
 955                 args += 6;
 956                 break;
 957             }
 958             goto do_default;
 959
 960         case INDEX_op_mulu2_i32:
 961             if (temps[args[2]].state == TCG_TEMP_CONST
 962                 && temps[args[3]].state == TCG_TEMP_CONST) {
 963                 uint32_t a = temps[args[2]].val;
 964                 uint32_t b = temps[args[3]].val;
 965                 uint64_t r = (uint64_t)a * b;
 966                 TCGArg rl, rh;
 967
 968                 /* We emit the extra nop when we emit the mulu2.  */
 969                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
 970
 971                 rl = args[0];
 972                 rh = args[1];
 973                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
 974                 s->gen_opc_buf[++op_index] = INDEX_op_movi_i32;
 975                 tcg_opt_gen_movi(&gen_args[0], rl, (uint32_t)r);
 976                 tcg_opt_gen_movi(&gen_args[2], rh, (uint32_t)(r >> 32));
 977                 gen_args += 4;
 978                 args += 4;
 979                 break;
 980             }
 981             goto do_default;
 982
 983         case INDEX_op_brcond2_i32:
 984             tmp = do_constant_folding_cond2(&args[0], &args[2], args[4]);
 985             if (tmp != 2) {
 986                 if (tmp) {
 987                     reset_all_temps(nb_temps);
 988                     s->gen_opc_buf[op_index] = INDEX_op_br;
 989                     gen_args[0] = args[5];
 990                     gen_args += 1;
 991                 } else {
 992                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 993                 }
 994             } else if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
 995                        && temps[args[2]].state == TCG_TEMP_CONST
 996                        && temps[args[3]].state == TCG_TEMP_CONST
 997                        && temps[args[2]].val == 0
 998                        && temps[args[3]].val == 0) {
 999                 /* Simplify LT/GE comparisons vs zero to a single compare
1000                    vs the high word of the input.  */
1001                 reset_all_temps(nb_temps);
1002                 s->gen_opc_buf[op_index] = INDEX_op_brcond_i32;
1003                 gen_args[0] = args[1];
1004                 gen_args[1] = args[3];
1005                 gen_args[2] = args[4];
1006                 gen_args[3] = args[5];
1007                 gen_args += 4;
1008             } else {
1009                 goto do_default;
1010             }
1011             args += 6;
1012             break;
1013
1014         case INDEX_op_setcond2_i32:
1015             tmp = do_constant_folding_cond2(&args[1], &args[3], args[5]);
1016             if (tmp != 2) {
1017                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
1018                 tcg_opt_gen_movi(gen_args, args[0], tmp);
1019                 gen_args += 2;
1020             } else if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
1021                        && temps[args[3]].state == TCG_TEMP_CONST
1022                        && temps[args[4]].state == TCG_TEMP_CONST
1023                        && temps[args[3]].val == 0
1024                        && temps[args[4]].val == 0) {
1025                 /* Simplify LT/GE comparisons vs zero to a single compare
1026                    vs the high word of the input.  */
1027                 s->gen_opc_buf[op_index] = INDEX_op_setcond_i32;
1028                 gen_args[0] = args[0];
1029                 gen_args[1] = args[2];
1030                 gen_args[2] = args[4];
1031                 gen_args[3] = args[5];
1032                 gen_args += 4;
1033             } else {
1034                 goto do_default;
1035             }
1036             args += 6;
1037             break;
1038
1039         case INDEX_op_call:
1040             nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
1041             if (!(args[nb_call_args + 1] & (TCG_CALL_NO_READ_GLOBALS |
1042                                             TCG_CALL_NO_WRITE_GLOBALS))) {
1043                 for (i = 0; i < nb_globals; i++) {
1044                     reset_temp(i);
1045                 }
1046             }
1047             for (i = 0; i < (args[0] >> 16); i++) {
1048                 reset_temp(args[i + 1]);
1049             }
1050             i = nb_call_args + 3;
1051             while (i) {
1052                 *gen_args = *args;
1053                 args++;
1054                 gen_args++;
1055                 i--;
1056             }
1057             break;
1058
1059         default:
1060         do_default:
1061             /* Default case: we know nothing about operation (or were unable
1062                to compute the operation result) so no propagation is done.
1063                We trash everything if the operation is the end of a basic
1064                block, otherwise we only trash the output args.  "mask" is
1065                the non-zero bits mask for the first output arg.  */
1066             if (def->flags & TCG_OPF_BB_END) {
1067                 reset_all_temps(nb_temps);
1068             } else {
1069                 for (i = 0; i < def->nb_oargs; i++) {
1070                     reset_temp(args[i]);
1071                 }
1072             }
1073             for (i = 0; i < def->nb_args; i++) {
1074                 gen_args[i] = args[i];
1075             }
1076             args += def->nb_args;
1077             gen_args += def->nb_args;
1078             break;
1079         }
1080     }
1081
1082     return gen_args;
1083 }
1084
1085 TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
1086         TCGArg *args, TCGOpDef *tcg_op_defs)
1087 {
1088     TCGArg *res;
1089     res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
1090     return res;
1091 }