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     uint64_t l64, h64;
 202
 203     switch (op) {
 204     CASE_OP_32_64(add):
 205         return x + y;
 206
 207     CASE_OP_32_64(sub):
 208         return x - y;
 209
 210     CASE_OP_32_64(mul):
 211         return x * y;
 212
 213     CASE_OP_32_64(and):
 214         return x & y;
 215
 216     CASE_OP_32_64(or):
 217         return x | y;
 218
 219     CASE_OP_32_64(xor):
 220         return x ^ y;
 221
 222     case INDEX_op_shl_i32:
 223         return (uint32_t)x << (uint32_t)y;
 224
 225     case INDEX_op_shl_i64:
 226         return (uint64_t)x << (uint64_t)y;
 227
 228     case INDEX_op_shr_i32:
 229         return (uint32_t)x >> (uint32_t)y;
 230
 231     case INDEX_op_shr_i64:
 232         return (uint64_t)x >> (uint64_t)y;
 233
 234     case INDEX_op_sar_i32:
 235         return (int32_t)x >> (int32_t)y;
 236
 237     case INDEX_op_sar_i64:
 238         return (int64_t)x >> (int64_t)y;
 239
 240     case INDEX_op_rotr_i32:
 241         x = ((uint32_t)x << (32 - y)) | ((uint32_t)x >> y);
 242         return x;
 243
 244     case INDEX_op_rotr_i64:
 245         x = ((uint64_t)x << (64 - y)) | ((uint64_t)x >> y);
 246         return x;
 247
 248     case INDEX_op_rotl_i32:
 249         x = ((uint32_t)x << y) | ((uint32_t)x >> (32 - y));
 250         return x;
 251
 252     case INDEX_op_rotl_i64:
 253         x = ((uint64_t)x << y) | ((uint64_t)x >> (64 - y));
 254         return x;
 255
 256     CASE_OP_32_64(not):
 257         return ~x;
 258
 259     CASE_OP_32_64(neg):
 260         return -x;
 261
 262     CASE_OP_32_64(andc):
 263         return x & ~y;
 264
 265     CASE_OP_32_64(orc):
 266         return x | ~y;
 267
 268     CASE_OP_32_64(eqv):
 269         return ~(x ^ y);
 270
 271     CASE_OP_32_64(nand):
 272         return ~(x & y);
 273
 274     CASE_OP_32_64(nor):
 275         return ~(x | y);
 276
 277     CASE_OP_32_64(ext8s):
 278         return (int8_t)x;
 279
 280     CASE_OP_32_64(ext16s):
 281         return (int16_t)x;
 282
 283     CASE_OP_32_64(ext8u):
 284         return (uint8_t)x;
 285
 286     CASE_OP_32_64(ext16u):
 287         return (uint16_t)x;
 288
 289     case INDEX_op_ext32s_i64:
 290         return (int32_t)x;
 291
 292     case INDEX_op_ext32u_i64:
 293         return (uint32_t)x;
 294
 295     case INDEX_op_muluh_i32:
 296         return ((uint64_t)(uint32_t)x * (uint32_t)y) >> 32;
 297     case INDEX_op_mulsh_i32:
 298         return ((int64_t)(int32_t)x * (int32_t)y) >> 32;
 299
 300     case INDEX_op_muluh_i64:
 301         mulu64(&l64, &h64, x, y);
 302         return h64;
 303     case INDEX_op_mulsh_i64:
 304         muls64(&l64, &h64, x, y);
 305         return h64;
 306
 307     case INDEX_op_div_i32:
 308         /* Avoid crashing on divide by zero, otherwise undefined.  */
 309         return (int32_t)x / ((int32_t)y ? : 1);
 310     case INDEX_op_divu_i32:
 311         return (uint32_t)x / ((uint32_t)y ? : 1);
 312     case INDEX_op_div_i64:
 313         return (int64_t)x / ((int64_t)y ? : 1);
 314     case INDEX_op_divu_i64:
 315         return (uint64_t)x / ((uint64_t)y ? : 1);
 316
 317     case INDEX_op_rem_i32:
 318         return (int32_t)x % ((int32_t)y ? : 1);
 319     case INDEX_op_remu_i32:
 320         return (uint32_t)x % ((uint32_t)y ? : 1);
 321     case INDEX_op_rem_i64:
 322         return (int64_t)x % ((int64_t)y ? : 1);
 323     case INDEX_op_remu_i64:
 324         return (uint64_t)x % ((uint64_t)y ? : 1);
 325
 326     default:
 327         fprintf(stderr,
 328                 "Unrecognized operation %d in do_constant_folding.\n", op);
 329         tcg_abort();
 330     }
 331 }
 332
 333 static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
 334 {
 335     TCGArg res = do_constant_folding_2(op, x, y);
 336     if (op_bits(op) == 32) {
 337         res &= 0xffffffff;
 338     }
 339     return res;
 340 }
 341
 342 static bool do_constant_folding_cond_32(uint32_t x, uint32_t y, TCGCond c)
 343 {
 344     switch (c) {
 345     case TCG_COND_EQ:
 346         return x == y;
 347     case TCG_COND_NE:
 348         return x != y;
 349     case TCG_COND_LT:
 350         return (int32_t)x < (int32_t)y;
 351     case TCG_COND_GE:
 352         return (int32_t)x >= (int32_t)y;
 353     case TCG_COND_LE:
 354         return (int32_t)x <= (int32_t)y;
 355     case TCG_COND_GT:
 356         return (int32_t)x > (int32_t)y;
 357     case TCG_COND_LTU:
 358         return x < y;
 359     case TCG_COND_GEU:
 360         return x >= y;
 361     case TCG_COND_LEU:
 362         return x <= y;
 363     case TCG_COND_GTU:
 364         return x > y;
 365     default:
 366         tcg_abort();
 367     }
 368 }
 369
 370 static bool do_constant_folding_cond_64(uint64_t x, uint64_t y, TCGCond c)
 371 {
 372     switch (c) {
 373     case TCG_COND_EQ:
 374         return x == y;
 375     case TCG_COND_NE:
 376         return x != y;
 377     case TCG_COND_LT:
 378         return (int64_t)x < (int64_t)y;
 379     case TCG_COND_GE:
 380         return (int64_t)x >= (int64_t)y;
 381     case TCG_COND_LE:
 382         return (int64_t)x <= (int64_t)y;
 383     case TCG_COND_GT:
 384         return (int64_t)x > (int64_t)y;
 385     case TCG_COND_LTU:
 386         return x < y;
 387     case TCG_COND_GEU:
 388         return x >= y;
 389     case TCG_COND_LEU:
 390         return x <= y;
 391     case TCG_COND_GTU:
 392         return x > y;
 393     default:
 394         tcg_abort();
 395     }
 396 }
 397
 398 static bool do_constant_folding_cond_eq(TCGCond c)
 399 {
 400     switch (c) {
 401     case TCG_COND_GT:
 402     case TCG_COND_LTU:
 403     case TCG_COND_LT:
 404     case TCG_COND_GTU:
 405     case TCG_COND_NE:
 406         return 0;
 407     case TCG_COND_GE:
 408     case TCG_COND_GEU:
 409     case TCG_COND_LE:
 410     case TCG_COND_LEU:
 411     case TCG_COND_EQ:
 412         return 1;
 413     default:
 414         tcg_abort();
 415     }
 416 }
 417
 418 /* Return 2 if the condition can't be simplified, and the result
 419    of the condition (0 or 1) if it can */
 420 static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
 421                                        TCGArg y, TCGCond c)
 422 {
 423     if (temps[x].state == TCG_TEMP_CONST && temps[y].state == TCG_TEMP_CONST) {
 424         switch (op_bits(op)) {
 425         case 32:
 426             return do_constant_folding_cond_32(temps[x].val, temps[y].val, c);
 427         case 64:
 428             return do_constant_folding_cond_64(temps[x].val, temps[y].val, c);
 429         default:
 430             tcg_abort();
 431         }
 432     } else if (temps_are_copies(x, y)) {
 433         return do_constant_folding_cond_eq(c);
 434     } else if (temps[y].state == TCG_TEMP_CONST && temps[y].val == 0) {
 435         switch (c) {
 436         case TCG_COND_LTU:
 437             return 0;
 438         case TCG_COND_GEU:
 439             return 1;
 440         default:
 441             return 2;
 442         }
 443     } else {
 444         return 2;
 445     }
 446 }
 447
 448 /* Return 2 if the condition can't be simplified, and the result
 449    of the condition (0 or 1) if it can */
 450 static TCGArg do_constant_folding_cond2(TCGArg *p1, TCGArg *p2, TCGCond c)
 451 {
 452     TCGArg al = p1[0], ah = p1[1];
 453     TCGArg bl = p2[0], bh = p2[1];
 454
 455     if (temps[bl].state == TCG_TEMP_CONST
 456         && temps[bh].state == TCG_TEMP_CONST) {
 457         uint64_t b = ((uint64_t)temps[bh].val << 32) | (uint32_t)temps[bl].val;
 458
 459         if (temps[al].state == TCG_TEMP_CONST
 460             && temps[ah].state == TCG_TEMP_CONST) {
 461             uint64_t a;
 462             a = ((uint64_t)temps[ah].val << 32) | (uint32_t)temps[al].val;
 463             return do_constant_folding_cond_64(a, b, c);
 464         }
 465         if (b == 0) {
 466             switch (c) {
 467             case TCG_COND_LTU:
 468                 return 0;
 469             case TCG_COND_GEU:
 470                 return 1;
 471             default:
 472                 break;
 473             }
 474         }
 475     }
 476     if (temps_are_copies(al, bl) && temps_are_copies(ah, bh)) {
 477         return do_constant_folding_cond_eq(c);
 478     }
 479     return 2;
 480 }
 481
 482 static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2)
 483 {
 484     TCGArg a1 = *p1, a2 = *p2;
 485     int sum = 0;
 486     sum += temps[a1].state == TCG_TEMP_CONST;
 487     sum -= temps[a2].state == TCG_TEMP_CONST;
 488
 489     /* Prefer the constant in second argument, and then the form
 490        op a, a, b, which is better handled on non-RISC hosts. */
 491     if (sum > 0 || (sum == 0 && dest == a2)) {
 492         *p1 = a2;
 493         *p2 = a1;
 494         return true;
 495     }
 496     return false;
 497 }
 498
 499 static bool swap_commutative2(TCGArg *p1, TCGArg *p2)
 500 {
 501     int sum = 0;
 502     sum += temps[p1[0]].state == TCG_TEMP_CONST;
 503     sum += temps[p1[1]].state == TCG_TEMP_CONST;
 504     sum -= temps[p2[0]].state == TCG_TEMP_CONST;
 505     sum -= temps[p2[1]].state == TCG_TEMP_CONST;
 506     if (sum > 0) {
 507         TCGArg t;
 508         t = p1[0], p1[0] = p2[0], p2[0] = t;
 509         t = p1[1], p1[1] = p2[1], p2[1] = t;
 510         return true;
 511     }
 512     return false;
 513 }
 514
 515 /* Propagate constants and copies, fold constant expressions. */
 516 static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
 517                                     TCGArg *args, TCGOpDef *tcg_op_defs)
 518 {
 519     int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;
 520     tcg_target_ulong mask, affected;
 521     TCGOpcode op;
 522     const TCGOpDef *def;
 523     TCGArg *gen_args;
 524     TCGArg tmp;
 525
 526     /* Array VALS has an element for each temp.
 527        If this temp holds a constant then its value is kept in VALS' element.
 528        If this temp is a copy of other ones then the other copies are
 529        available through the doubly linked circular list. */
 530
 531     nb_temps = s->nb_temps;
 532     nb_globals = s->nb_globals;
 533     reset_all_temps(nb_temps);
 534
 535     nb_ops = tcg_opc_ptr - s->gen_opc_buf;
 536     gen_args = args;
 537     for (op_index = 0; op_index < nb_ops; op_index++) {
 538         op = s->gen_opc_buf[op_index];
 539         def = &tcg_op_defs[op];
 540         /* Do copy propagation */
 541         if (op == INDEX_op_call) {
 542             int nb_oargs = args[0] >> 16;
 543             int nb_iargs = args[0] & 0xffff;
 544             for (i = nb_oargs + 1; i < nb_oargs + nb_iargs + 1; i++) {
 545                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 546                     args[i] = find_better_copy(s, args[i]);
 547                 }
 548             }
 549         } else {
 550             for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
 551                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 552                     args[i] = find_better_copy(s, args[i]);
 553                 }
 554             }
 555         }
 556
 557         /* For commutative operations make constant second argument */
 558         switch (op) {
 559         CASE_OP_32_64(add):
 560         CASE_OP_32_64(mul):
 561         CASE_OP_32_64(and):
 562         CASE_OP_32_64(or):
 563         CASE_OP_32_64(xor):
 564         CASE_OP_32_64(eqv):
 565         CASE_OP_32_64(nand):
 566         CASE_OP_32_64(nor):
 567         CASE_OP_32_64(muluh):
 568         CASE_OP_32_64(mulsh):
 569             swap_commutative(args[0], &args[1], &args[2]);
 570             break;
 571         CASE_OP_32_64(brcond):
 572             if (swap_commutative(-1, &args[0], &args[1])) {
 573                 args[2] = tcg_swap_cond(args[2]);
 574             }
 575             break;
 576         CASE_OP_32_64(setcond):
 577             if (swap_commutative(args[0], &args[1], &args[2])) {
 578                 args[3] = tcg_swap_cond(args[3]);
 579             }
 580             break;
 581         CASE_OP_32_64(movcond):
 582             if (swap_commutative(-1, &args[1], &args[2])) {
 583                 args[5] = tcg_swap_cond(args[5]);
 584             }
 585             /* For movcond, we canonicalize the "false" input reg to match
 586                the destination reg so that the tcg backend can implement
 587                a "move if true" operation.  */
 588             if (swap_commutative(args[0], &args[4], &args[3])) {
 589                 args[5] = tcg_invert_cond(args[5]);
 590             }
 591             break;
 592         CASE_OP_32_64(add2):
 593             swap_commutative(args[0], &args[2], &args[4]);
 594             swap_commutative(args[1], &args[3], &args[5]);
 595             break;
 596         CASE_OP_32_64(mulu2):
 597         CASE_OP_32_64(muls2):
 598             swap_commutative(args[0], &args[2], &args[3]);
 599             break;
 600         case INDEX_op_brcond2_i32:
 601             if (swap_commutative2(&args[0], &args[2])) {
 602                 args[4] = tcg_swap_cond(args[4]);
 603             }
 604             break;
 605         case INDEX_op_setcond2_i32:
 606             if (swap_commutative2(&args[1], &args[3])) {
 607                 args[5] = tcg_swap_cond(args[5]);
 608             }
 609             break;
 610         default:
 611             break;
 612         }
 613
 614         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0",
 615            and "sub r, 0, a => neg r, a" case.  */
 616         switch (op) {
 617         CASE_OP_32_64(shl):
 618         CASE_OP_32_64(shr):
 619         CASE_OP_32_64(sar):
 620         CASE_OP_32_64(rotl):
 621         CASE_OP_32_64(rotr):
 622             if (temps[args[1]].state == TCG_TEMP_CONST
 623                 && temps[args[1]].val == 0) {
 624                 s->gen_opc_buf[op_index] = op_to_movi(op);
 625                 tcg_opt_gen_movi(gen_args, args[0], 0);
 626                 args += 3;
 627                 gen_args += 2;
 628                 continue;
 629             }
 630             break;
 631         CASE_OP_32_64(sub):
 632             {
 633                 TCGOpcode neg_op;
 634                 bool have_neg;
 635
 636                 if (temps[args[2]].state == TCG_TEMP_CONST) {
 637                     /* Proceed with possible constant folding. */
 638                     break;
 639                 }
 640                 if (op == INDEX_op_sub_i32) {
 641                     neg_op = INDEX_op_neg_i32;
 642                     have_neg = TCG_TARGET_HAS_neg_i32;
 643                 } else {
 644                     neg_op = INDEX_op_neg_i64;
 645                     have_neg = TCG_TARGET_HAS_neg_i64;
 646                 }
 647                 if (!have_neg) {
 648                     break;
 649                 }
 650                 if (temps[args[1]].state == TCG_TEMP_CONST
 651                     && temps[args[1]].val == 0) {
 652                     s->gen_opc_buf[op_index] = neg_op;
 653                     reset_temp(args[0]);
 654                     gen_args[0] = args[0];
 655                     gen_args[1] = args[2];
 656                     args += 3;
 657                     gen_args += 2;
 658                     continue;
 659                 }
 660             }
 661             break;
 662         default:
 663             break;
 664         }
 665
 666         /* Simplify expression for "op r, a, 0 => mov r, a" cases */
 667         switch (op) {
 668         CASE_OP_32_64(add):
 669         CASE_OP_32_64(sub):
 670         CASE_OP_32_64(shl):
 671         CASE_OP_32_64(shr):
 672         CASE_OP_32_64(sar):
 673         CASE_OP_32_64(rotl):
 674         CASE_OP_32_64(rotr):
 675         CASE_OP_32_64(or):
 676         CASE_OP_32_64(xor):
 677             if (temps[args[1]].state == TCG_TEMP_CONST) {
 678                 /* Proceed with possible constant folding. */
 679                 break;
 680             }
 681             if (temps[args[2]].state == TCG_TEMP_CONST
 682                 && temps[args[2]].val == 0) {
 683                 if (temps_are_copies(args[0], args[1])) {
 684                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 685                 } else {
 686                     s->gen_opc_buf[op_index] = op_to_mov(op);
 687                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 688                     gen_args += 2;
 689                 }
 690                 args += 3;
 691                 continue;
 692             }
 693             break;
 694         default:
 695             break;
 696         }
 697
 698         /* Simplify using known-zero bits */
 699         mask = -1;
 700         affected = -1;
 701         switch (op) {
 702         CASE_OP_32_64(ext8s):
 703             if ((temps[args[1]].mask & 0x80) != 0) {
 704                 break;
 705             }
 706         CASE_OP_32_64(ext8u):
 707             mask = 0xff;
 708             goto and_const;
 709         CASE_OP_32_64(ext16s):
 710             if ((temps[args[1]].mask & 0x8000) != 0) {
 711                 break;
 712             }
 713         CASE_OP_32_64(ext16u):
 714             mask = 0xffff;
 715             goto and_const;
 716         case INDEX_op_ext32s_i64:
 717             if ((temps[args[1]].mask & 0x80000000) != 0) {
 718                 break;
 719             }
 720         case INDEX_op_ext32u_i64:
 721             mask = 0xffffffffU;
 722             goto and_const;
 723
 724         CASE_OP_32_64(and):
 725             mask = temps[args[2]].mask;
 726             if (temps[args[2]].state == TCG_TEMP_CONST) {
 727         and_const:
 728                 affected = temps[args[1]].mask & ~mask;
 729             }
 730             mask = temps[args[1]].mask & mask;
 731             break;
 732
 733         CASE_OP_32_64(sar):
 734             if (temps[args[2]].state == TCG_TEMP_CONST) {
 735                 mask = ((tcg_target_long)temps[args[1]].mask
 736                         >> temps[args[2]].val);
 737             }
 738             break;
 739
 740         CASE_OP_32_64(shr):
 741             if (temps[args[2]].state == TCG_TEMP_CONST) {
 742                 mask = temps[args[1]].mask >> temps[args[2]].val;
 743             }
 744             break;
 745
 746         CASE_OP_32_64(shl):
 747             if (temps[args[2]].state == TCG_TEMP_CONST) {
 748                 mask = temps[args[1]].mask << temps[args[2]].val;
 749             }
 750             break;
 751
 752         CASE_OP_32_64(neg):
 753             /* Set to 1 all bits to the left of the rightmost.  */
 754             mask = -(temps[args[1]].mask & -temps[args[1]].mask);
 755             break;
 756
 757         CASE_OP_32_64(deposit):
 758             tmp = ((1ull << args[4]) - 1);
 759             mask = ((temps[args[1]].mask & ~(tmp << args[3]))
 760                     | ((temps[args[2]].mask & tmp) << args[3]));
 761             break;
 762
 763         CASE_OP_32_64(or):
 764         CASE_OP_32_64(xor):
 765             mask = temps[args[1]].mask | temps[args[2]].mask;
 766             break;
 767
 768         CASE_OP_32_64(setcond):
 769             mask = 1;
 770             break;
 771
 772         CASE_OP_32_64(movcond):
 773             mask = temps[args[3]].mask | temps[args[4]].mask;
 774             break;
 775
 776         default:
 777             break;
 778         }
 779
 780         if (mask == 0) {
 781             assert(def->nb_oargs == 1);
 782             s->gen_opc_buf[op_index] = op_to_movi(op);
 783             tcg_opt_gen_movi(gen_args, args[0], 0);
 784             args += def->nb_oargs + def->nb_iargs + def->nb_cargs;
 785             gen_args += 2;
 786             continue;
 787         }
 788         if (affected == 0) {
 789             assert(def->nb_oargs == 1);
 790             if (temps_are_copies(args[0], args[1])) {
 791                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 792             } else if (temps[args[1]].state != TCG_TEMP_CONST) {
 793                 s->gen_opc_buf[op_index] = op_to_mov(op);
 794                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 795                 gen_args += 2;
 796             } else {
 797                 s->gen_opc_buf[op_index] = op_to_movi(op);
 798                 tcg_opt_gen_movi(gen_args, args[0], temps[args[1]].val);
 799                 gen_args += 2;
 800             }
 801             args += def->nb_iargs + 1;
 802             continue;
 803         }
 804
 805         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 806         switch (op) {
 807         CASE_OP_32_64(and):
 808         CASE_OP_32_64(mul):
 809         CASE_OP_32_64(muluh):
 810         CASE_OP_32_64(mulsh):
 811             if ((temps[args[2]].state == TCG_TEMP_CONST
 812                 && temps[args[2]].val == 0)) {
 813                 s->gen_opc_buf[op_index] = op_to_movi(op);
 814                 tcg_opt_gen_movi(gen_args, args[0], 0);
 815                 args += 3;
 816                 gen_args += 2;
 817                 continue;
 818             }
 819             break;
 820         default:
 821             break;
 822         }
 823
 824         /* Simplify expression for "op r, a, a => mov r, a" cases */
 825         switch (op) {
 826         CASE_OP_32_64(or):
 827         CASE_OP_32_64(and):
 828             if (temps_are_copies(args[1], args[2])) {
 829                 if (temps_are_copies(args[0], args[1])) {
 830                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 831                 } else {
 832                     s->gen_opc_buf[op_index] = op_to_mov(op);
 833                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 834                     gen_args += 2;
 835                 }
 836                 args += 3;
 837                 continue;
 838             }
 839             break;
 840         default:
 841             break;
 842         }
 843
 844         /* Simplify expression for "op r, a, a => movi r, 0" cases */
 845         switch (op) {
 846         CASE_OP_32_64(sub):
 847         CASE_OP_32_64(xor):
 848             if (temps_are_copies(args[1], args[2])) {
 849                 s->gen_opc_buf[op_index] = op_to_movi(op);
 850                 tcg_opt_gen_movi(gen_args, args[0], 0);
 851                 gen_args += 2;
 852                 args += 3;
 853                 continue;
 854             }
 855             break;
 856         default:
 857             break;
 858         }
 859
 860         /* Propagate constants through copy operations and do constant
 861            folding.  Constants will be substituted to arguments by register
 862            allocator where needed and possible.  Also detect copies. */
 863         switch (op) {
 864         CASE_OP_32_64(mov):
 865             if (temps_are_copies(args[0], args[1])) {
 866                 args += 2;
 867                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 868                 break;
 869             }
 870             if (temps[args[1]].state != TCG_TEMP_CONST) {
 871                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 872                 gen_args += 2;
 873                 args += 2;
 874                 break;
 875             }
 876             /* Source argument is constant.  Rewrite the operation and
 877                let movi case handle it. */
 878             op = op_to_movi(op);
 879             s->gen_opc_buf[op_index] = op;
 880             args[1] = temps[args[1]].val;
 881             /* fallthrough */
 882         CASE_OP_32_64(movi):
 883             tcg_opt_gen_movi(gen_args, args[0], args[1]);
 884             gen_args += 2;
 885             args += 2;
 886             break;
 887
 888         CASE_OP_32_64(not):
 889         CASE_OP_32_64(neg):
 890         CASE_OP_32_64(ext8s):
 891         CASE_OP_32_64(ext8u):
 892         CASE_OP_32_64(ext16s):
 893         CASE_OP_32_64(ext16u):
 894         case INDEX_op_ext32s_i64:
 895         case INDEX_op_ext32u_i64:
 896             if (temps[args[1]].state == TCG_TEMP_CONST) {
 897                 s->gen_opc_buf[op_index] = op_to_movi(op);
 898                 tmp = do_constant_folding(op, temps[args[1]].val, 0);
 899                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 900                 gen_args += 2;
 901                 args += 2;
 902                 break;
 903             }
 904             goto do_default;
 905
 906         CASE_OP_32_64(add):
 907         CASE_OP_32_64(sub):
 908         CASE_OP_32_64(mul):
 909         CASE_OP_32_64(or):
 910         CASE_OP_32_64(and):
 911         CASE_OP_32_64(xor):
 912         CASE_OP_32_64(shl):
 913         CASE_OP_32_64(shr):
 914         CASE_OP_32_64(sar):
 915         CASE_OP_32_64(rotl):
 916         CASE_OP_32_64(rotr):
 917         CASE_OP_32_64(andc):
 918         CASE_OP_32_64(orc):
 919         CASE_OP_32_64(eqv):
 920         CASE_OP_32_64(nand):
 921         CASE_OP_32_64(nor):
 922         CASE_OP_32_64(muluh):
 923         CASE_OP_32_64(mulsh):
 924         CASE_OP_32_64(div):
 925         CASE_OP_32_64(divu):
 926         CASE_OP_32_64(rem):
 927         CASE_OP_32_64(remu):
 928             if (temps[args[1]].state == TCG_TEMP_CONST
 929                 && temps[args[2]].state == TCG_TEMP_CONST) {
 930                 s->gen_opc_buf[op_index] = op_to_movi(op);
 931                 tmp = do_constant_folding(op, temps[args[1]].val,
 932                                           temps[args[2]].val);
 933                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 934                 gen_args += 2;
 935                 args += 3;
 936                 break;
 937             }
 938             goto do_default;
 939
 940         CASE_OP_32_64(deposit):
 941             if (temps[args[1]].state == TCG_TEMP_CONST
 942                 && temps[args[2]].state == TCG_TEMP_CONST) {
 943                 s->gen_opc_buf[op_index] = op_to_movi(op);
 944                 tmp = ((1ull << args[4]) - 1);
 945                 tmp = (temps[args[1]].val & ~(tmp << args[3]))
 946                       | ((temps[args[2]].val & tmp) << args[3]);
 947                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 948                 gen_args += 2;
 949                 args += 5;
 950                 break;
 951             }
 952             goto do_default;
 953
 954         CASE_OP_32_64(setcond):
 955             tmp = do_constant_folding_cond(op, args[1], args[2], args[3]);
 956             if (tmp != 2) {
 957                 s->gen_opc_buf[op_index] = op_to_movi(op);
 958                 tcg_opt_gen_movi(gen_args, args[0], tmp);
 959                 gen_args += 2;
 960                 args += 4;
 961                 break;
 962             }
 963             goto do_default;
 964
 965         CASE_OP_32_64(brcond):
 966             tmp = do_constant_folding_cond(op, args[0], args[1], args[2]);
 967             if (tmp != 2) {
 968                 if (tmp) {
 969                     reset_all_temps(nb_temps);
 970                     s->gen_opc_buf[op_index] = INDEX_op_br;
 971                     gen_args[0] = args[3];
 972                     gen_args += 1;
 973                 } else {
 974                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 975                 }
 976                 args += 4;
 977                 break;
 978             }
 979             goto do_default;
 980
 981         CASE_OP_32_64(movcond):
 982             tmp = do_constant_folding_cond(op, args[1], args[2], args[5]);
 983             if (tmp != 2) {
 984                 if (temps_are_copies(args[0], args[4-tmp])) {
 985                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 986                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
 987                     s->gen_opc_buf[op_index] = op_to_movi(op);
 988                     tcg_opt_gen_movi(gen_args, args[0], temps[args[4-tmp]].val);
 989                     gen_args += 2;
 990                 } else {
 991                     s->gen_opc_buf[op_index] = op_to_mov(op);
 992                     tcg_opt_gen_mov(s, gen_args, args[0], args[4-tmp]);
 993                     gen_args += 2;
 994                 }
 995                 args += 6;
 996                 break;
 997             }
 998             goto do_default;
 999
1000         case INDEX_op_add2_i32:
1001         case INDEX_op_sub2_i32:
1002             if (temps[args[2]].state == TCG_TEMP_CONST
1003                 && temps[args[3]].state == TCG_TEMP_CONST
1004                 && temps[args[4]].state == TCG_TEMP_CONST
1005                 && temps[args[5]].state == TCG_TEMP_CONST) {
1006                 uint32_t al = temps[args[2]].val;
1007                 uint32_t ah = temps[args[3]].val;
1008                 uint32_t bl = temps[args[4]].val;
1009                 uint32_t bh = temps[args[5]].val;
1010                 uint64_t a = ((uint64_t)ah << 32) | al;
1011                 uint64_t b = ((uint64_t)bh << 32) | bl;
1012                 TCGArg rl, rh;
1013
1014                 if (op == INDEX_op_add2_i32) {
1015                     a += b;
1016                 } else {
1017                     a -= b;
1018                 }
1019
1020                 /* We emit the extra nop when we emit the add2/sub2.  */
1021                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
1022
1023                 rl = args[0];
1024                 rh = args[1];
1025                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
1026                 s->gen_opc_buf[++op_index] = INDEX_op_movi_i32;
1027                 tcg_opt_gen_movi(&gen_args[0], rl, (uint32_t)a);
1028                 tcg_opt_gen_movi(&gen_args[2], rh, (uint32_t)(a >> 32));
1029                 gen_args += 4;
1030                 args += 6;
1031                 break;
1032             }
1033             goto do_default;
1034
1035         case INDEX_op_mulu2_i32:
1036             if (temps[args[2]].state == TCG_TEMP_CONST
1037                 && temps[args[3]].state == TCG_TEMP_CONST) {
1038                 uint32_t a = temps[args[2]].val;
1039                 uint32_t b = temps[args[3]].val;
1040                 uint64_t r = (uint64_t)a * b;
1041                 TCGArg rl, rh;
1042
1043                 /* We emit the extra nop when we emit the mulu2.  */
1044                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
1045
1046                 rl = args[0];
1047                 rh = args[1];
1048                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
1049                 s->gen_opc_buf[++op_index] = INDEX_op_movi_i32;
1050                 tcg_opt_gen_movi(&gen_args[0], rl, (uint32_t)r);
1051                 tcg_opt_gen_movi(&gen_args[2], rh, (uint32_t)(r >> 32));
1052                 gen_args += 4;
1053                 args += 4;
1054                 break;
1055             }
1056             goto do_default;
1057
1058         case INDEX_op_brcond2_i32:
1059             tmp = do_constant_folding_cond2(&args[0], &args[2], args[4]);
1060             if (tmp != 2) {
1061                 if (tmp) {
1062                     reset_all_temps(nb_temps);
1063                     s->gen_opc_buf[op_index] = INDEX_op_br;
1064                     gen_args[0] = args[5];
1065                     gen_args += 1;
1066                 } else {
1067                     s->gen_opc_buf[op_index] = INDEX_op_nop;
1068                 }
1069             } else if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
1070                        && temps[args[2]].state == TCG_TEMP_CONST
1071                        && temps[args[3]].state == TCG_TEMP_CONST
1072                        && temps[args[2]].val == 0
1073                        && temps[args[3]].val == 0) {
1074                 /* Simplify LT/GE comparisons vs zero to a single compare
1075                    vs the high word of the input.  */
1076                 reset_all_temps(nb_temps);
1077                 s->gen_opc_buf[op_index] = INDEX_op_brcond_i32;
1078                 gen_args[0] = args[1];
1079                 gen_args[1] = args[3];
1080                 gen_args[2] = args[4];
1081                 gen_args[3] = args[5];
1082                 gen_args += 4;
1083             } else {
1084                 goto do_default;
1085             }
1086             args += 6;
1087             break;
1088
1089         case INDEX_op_setcond2_i32:
1090             tmp = do_constant_folding_cond2(&args[1], &args[3], args[5]);
1091             if (tmp != 2) {
1092                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
1093                 tcg_opt_gen_movi(gen_args, args[0], tmp);
1094                 gen_args += 2;
1095             } else if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
1096                        && temps[args[3]].state == TCG_TEMP_CONST
1097                        && temps[args[4]].state == TCG_TEMP_CONST
1098                        && temps[args[3]].val == 0
1099                        && temps[args[4]].val == 0) {
1100                 /* Simplify LT/GE comparisons vs zero to a single compare
1101                    vs the high word of the input.  */
1102                 s->gen_opc_buf[op_index] = INDEX_op_setcond_i32;
1103                 reset_temp(args[0]);
1104                 gen_args[0] = args[0];
1105                 gen_args[1] = args[2];
1106                 gen_args[2] = args[4];
1107                 gen_args[3] = args[5];
1108                 gen_args += 4;
1109             } else {
1110                 goto do_default;
1111             }
1112             args += 6;
1113             break;
1114
1115         case INDEX_op_call:
1116             nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
1117             if (!(args[nb_call_args + 1] & (TCG_CALL_NO_READ_GLOBALS |
1118                                             TCG_CALL_NO_WRITE_GLOBALS))) {
1119                 for (i = 0; i < nb_globals; i++) {
1120                     reset_temp(i);
1121                 }
1122             }
1123             for (i = 0; i < (args[0] >> 16); i++) {
1124                 reset_temp(args[i + 1]);
1125             }
1126             i = nb_call_args + 3;
1127             while (i) {
1128                 *gen_args = *args;
1129                 args++;
1130                 gen_args++;
1131                 i--;
1132             }
1133             break;
1134
1135         default:
1136         do_default:
1137             /* Default case: we know nothing about operation (or were unable
1138                to compute the operation result) so no propagation is done.
1139                We trash everything if the operation is the end of a basic
1140                block, otherwise we only trash the output args.  "mask" is
1141                the non-zero bits mask for the first output arg.  */
1142             if (def->flags & TCG_OPF_BB_END) {
1143                 reset_all_temps(nb_temps);
1144             } else {
1145                 for (i = 0; i < def->nb_oargs; i++) {
1146                     reset_temp(args[i]);
1147                 }
1148             }
1149             for (i = 0; i < def->nb_args; i++) {
1150                 gen_args[i] = args[i];
1151             }
1152             args += def->nb_args;
1153             gen_args += def->nb_args;
1154             break;
1155         }
1156     }
1157
1158     return gen_args;
1159 }
1160
1161 TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
1162         TCGArg *args, TCGOpDef *tcg_op_defs)
1163 {
1164     TCGArg *res;
1165     res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
1166     return res;
1167 }