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         return ror32(x, y);
 242
 243     case INDEX_op_rotr_i64:
 244         return ror64(x, y);
 245
 246     case INDEX_op_rotl_i32:
 247         return rol32(x, y);
 248
 249     case INDEX_op_rotl_i64:
 250         return rol64(x, y);
 251
 252     CASE_OP_32_64(not):
 253         return ~x;
 254
 255     CASE_OP_32_64(neg):
 256         return -x;
 257
 258     CASE_OP_32_64(andc):
 259         return x & ~y;
 260
 261     CASE_OP_32_64(orc):
 262         return x | ~y;
 263
 264     CASE_OP_32_64(eqv):
 265         return ~(x ^ y);
 266
 267     CASE_OP_32_64(nand):
 268         return ~(x & y);
 269
 270     CASE_OP_32_64(nor):
 271         return ~(x | y);
 272
 273     CASE_OP_32_64(ext8s):
 274         return (int8_t)x;
 275
 276     CASE_OP_32_64(ext16s):
 277         return (int16_t)x;
 278
 279     CASE_OP_32_64(ext8u):
 280         return (uint8_t)x;
 281
 282     CASE_OP_32_64(ext16u):
 283         return (uint16_t)x;
 284
 285     case INDEX_op_ext32s_i64:
 286         return (int32_t)x;
 287
 288     case INDEX_op_ext32u_i64:
 289         return (uint32_t)x;
 290
 291     case INDEX_op_muluh_i32:
 292         return ((uint64_t)(uint32_t)x * (uint32_t)y) >> 32;
 293     case INDEX_op_mulsh_i32:
 294         return ((int64_t)(int32_t)x * (int32_t)y) >> 32;
 295
 296     case INDEX_op_muluh_i64:
 297         mulu64(&l64, &h64, x, y);
 298         return h64;
 299     case INDEX_op_mulsh_i64:
 300         muls64(&l64, &h64, x, y);
 301         return h64;
 302
 303     case INDEX_op_div_i32:
 304         /* Avoid crashing on divide by zero, otherwise undefined.  */
 305         return (int32_t)x / ((int32_t)y ? : 1);
 306     case INDEX_op_divu_i32:
 307         return (uint32_t)x / ((uint32_t)y ? : 1);
 308     case INDEX_op_div_i64:
 309         return (int64_t)x / ((int64_t)y ? : 1);
 310     case INDEX_op_divu_i64:
 311         return (uint64_t)x / ((uint64_t)y ? : 1);
 312
 313     case INDEX_op_rem_i32:
 314         return (int32_t)x % ((int32_t)y ? : 1);
 315     case INDEX_op_remu_i32:
 316         return (uint32_t)x % ((uint32_t)y ? : 1);
 317     case INDEX_op_rem_i64:
 318         return (int64_t)x % ((int64_t)y ? : 1);
 319     case INDEX_op_remu_i64:
 320         return (uint64_t)x % ((uint64_t)y ? : 1);
 321
 322     default:
 323         fprintf(stderr,
 324                 "Unrecognized operation %d in do_constant_folding.\n", op);
 325         tcg_abort();
 326     }
 327 }
 328
 329 static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
 330 {
 331     TCGArg res = do_constant_folding_2(op, x, y);
 332     if (op_bits(op) == 32) {
 333         res &= 0xffffffff;
 334     }
 335     return res;
 336 }
 337
 338 static bool do_constant_folding_cond_32(uint32_t x, uint32_t y, TCGCond c)
 339 {
 340     switch (c) {
 341     case TCG_COND_EQ:
 342         return x == y;
 343     case TCG_COND_NE:
 344         return x != y;
 345     case TCG_COND_LT:
 346         return (int32_t)x < (int32_t)y;
 347     case TCG_COND_GE:
 348         return (int32_t)x >= (int32_t)y;
 349     case TCG_COND_LE:
 350         return (int32_t)x <= (int32_t)y;
 351     case TCG_COND_GT:
 352         return (int32_t)x > (int32_t)y;
 353     case TCG_COND_LTU:
 354         return x < y;
 355     case TCG_COND_GEU:
 356         return x >= y;
 357     case TCG_COND_LEU:
 358         return x <= y;
 359     case TCG_COND_GTU:
 360         return x > y;
 361     default:
 362         tcg_abort();
 363     }
 364 }
 365
 366 static bool do_constant_folding_cond_64(uint64_t x, uint64_t y, TCGCond c)
 367 {
 368     switch (c) {
 369     case TCG_COND_EQ:
 370         return x == y;
 371     case TCG_COND_NE:
 372         return x != y;
 373     case TCG_COND_LT:
 374         return (int64_t)x < (int64_t)y;
 375     case TCG_COND_GE:
 376         return (int64_t)x >= (int64_t)y;
 377     case TCG_COND_LE:
 378         return (int64_t)x <= (int64_t)y;
 379     case TCG_COND_GT:
 380         return (int64_t)x > (int64_t)y;
 381     case TCG_COND_LTU:
 382         return x < y;
 383     case TCG_COND_GEU:
 384         return x >= y;
 385     case TCG_COND_LEU:
 386         return x <= y;
 387     case TCG_COND_GTU:
 388         return x > y;
 389     default:
 390         tcg_abort();
 391     }
 392 }
 393
 394 static bool do_constant_folding_cond_eq(TCGCond c)
 395 {
 396     switch (c) {
 397     case TCG_COND_GT:
 398     case TCG_COND_LTU:
 399     case TCG_COND_LT:
 400     case TCG_COND_GTU:
 401     case TCG_COND_NE:
 402         return 0;
 403     case TCG_COND_GE:
 404     case TCG_COND_GEU:
 405     case TCG_COND_LE:
 406     case TCG_COND_LEU:
 407     case TCG_COND_EQ:
 408         return 1;
 409     default:
 410         tcg_abort();
 411     }
 412 }
 413
 414 /* Return 2 if the condition can't be simplified, and the result
 415    of the condition (0 or 1) if it can */
 416 static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
 417                                        TCGArg y, TCGCond c)
 418 {
 419     if (temps[x].state == TCG_TEMP_CONST && temps[y].state == TCG_TEMP_CONST) {
 420         switch (op_bits(op)) {
 421         case 32:
 422             return do_constant_folding_cond_32(temps[x].val, temps[y].val, c);
 423         case 64:
 424             return do_constant_folding_cond_64(temps[x].val, temps[y].val, c);
 425         default:
 426             tcg_abort();
 427         }
 428     } else if (temps_are_copies(x, y)) {
 429         return do_constant_folding_cond_eq(c);
 430     } else if (temps[y].state == TCG_TEMP_CONST && temps[y].val == 0) {
 431         switch (c) {
 432         case TCG_COND_LTU:
 433             return 0;
 434         case TCG_COND_GEU:
 435             return 1;
 436         default:
 437             return 2;
 438         }
 439     } else {
 440         return 2;
 441     }
 442 }
 443
 444 /* Return 2 if the condition can't be simplified, and the result
 445    of the condition (0 or 1) if it can */
 446 static TCGArg do_constant_folding_cond2(TCGArg *p1, TCGArg *p2, TCGCond c)
 447 {
 448     TCGArg al = p1[0], ah = p1[1];
 449     TCGArg bl = p2[0], bh = p2[1];
 450
 451     if (temps[bl].state == TCG_TEMP_CONST
 452         && temps[bh].state == TCG_TEMP_CONST) {
 453         uint64_t b = ((uint64_t)temps[bh].val << 32) | (uint32_t)temps[bl].val;
 454
 455         if (temps[al].state == TCG_TEMP_CONST
 456             && temps[ah].state == TCG_TEMP_CONST) {
 457             uint64_t a;
 458             a = ((uint64_t)temps[ah].val << 32) | (uint32_t)temps[al].val;
 459             return do_constant_folding_cond_64(a, b, c);
 460         }
 461         if (b == 0) {
 462             switch (c) {
 463             case TCG_COND_LTU:
 464                 return 0;
 465             case TCG_COND_GEU:
 466                 return 1;
 467             default:
 468                 break;
 469             }
 470         }
 471     }
 472     if (temps_are_copies(al, bl) && temps_are_copies(ah, bh)) {
 473         return do_constant_folding_cond_eq(c);
 474     }
 475     return 2;
 476 }
 477
 478 static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2)
 479 {
 480     TCGArg a1 = *p1, a2 = *p2;
 481     int sum = 0;
 482     sum += temps[a1].state == TCG_TEMP_CONST;
 483     sum -= temps[a2].state == TCG_TEMP_CONST;
 484
 485     /* Prefer the constant in second argument, and then the form
 486        op a, a, b, which is better handled on non-RISC hosts. */
 487     if (sum > 0 || (sum == 0 && dest == a2)) {
 488         *p1 = a2;
 489         *p2 = a1;
 490         return true;
 491     }
 492     return false;
 493 }
 494
 495 static bool swap_commutative2(TCGArg *p1, TCGArg *p2)
 496 {
 497     int sum = 0;
 498     sum += temps[p1[0]].state == TCG_TEMP_CONST;
 499     sum += temps[p1[1]].state == TCG_TEMP_CONST;
 500     sum -= temps[p2[0]].state == TCG_TEMP_CONST;
 501     sum -= temps[p2[1]].state == TCG_TEMP_CONST;
 502     if (sum > 0) {
 503         TCGArg t;
 504         t = p1[0], p1[0] = p2[0], p2[0] = t;
 505         t = p1[1], p1[1] = p2[1], p2[1] = t;
 506         return true;
 507     }
 508     return false;
 509 }
 510
 511 /* Propagate constants and copies, fold constant expressions. */
 512 static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
 513                                     TCGArg *args, TCGOpDef *tcg_op_defs)
 514 {
 515     int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;
 516     tcg_target_ulong mask, affected;
 517     TCGOpcode op;
 518     const TCGOpDef *def;
 519     TCGArg *gen_args;
 520     TCGArg tmp;
 521
 522     /* Array VALS has an element for each temp.
 523        If this temp holds a constant then its value is kept in VALS' element.
 524        If this temp is a copy of other ones then the other copies are
 525        available through the doubly linked circular list. */
 526
 527     nb_temps = s->nb_temps;
 528     nb_globals = s->nb_globals;
 529     reset_all_temps(nb_temps);
 530
 531     nb_ops = tcg_opc_ptr - s->gen_opc_buf;
 532     gen_args = args;
 533     for (op_index = 0; op_index < nb_ops; op_index++) {
 534         op = s->gen_opc_buf[op_index];
 535         def = &tcg_op_defs[op];
 536         /* Do copy propagation */
 537         if (op == INDEX_op_call) {
 538             int nb_oargs = args[0] >> 16;
 539             int nb_iargs = args[0] & 0xffff;
 540             for (i = nb_oargs + 1; i < nb_oargs + nb_iargs + 1; i++) {
 541                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 542                     args[i] = find_better_copy(s, args[i]);
 543                 }
 544             }
 545         } else {
 546             for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
 547                 if (temps[args[i]].state == TCG_TEMP_COPY) {
 548                     args[i] = find_better_copy(s, args[i]);
 549                 }
 550             }
 551         }
 552
 553         /* For commutative operations make constant second argument */
 554         switch (op) {
 555         CASE_OP_32_64(add):
 556         CASE_OP_32_64(mul):
 557         CASE_OP_32_64(and):
 558         CASE_OP_32_64(or):
 559         CASE_OP_32_64(xor):
 560         CASE_OP_32_64(eqv):
 561         CASE_OP_32_64(nand):
 562         CASE_OP_32_64(nor):
 563         CASE_OP_32_64(muluh):
 564         CASE_OP_32_64(mulsh):
 565             swap_commutative(args[0], &args[1], &args[2]);
 566             break;
 567         CASE_OP_32_64(brcond):
 568             if (swap_commutative(-1, &args[0], &args[1])) {
 569                 args[2] = tcg_swap_cond(args[2]);
 570             }
 571             break;
 572         CASE_OP_32_64(setcond):
 573             if (swap_commutative(args[0], &args[1], &args[2])) {
 574                 args[3] = tcg_swap_cond(args[3]);
 575             }
 576             break;
 577         CASE_OP_32_64(movcond):
 578             if (swap_commutative(-1, &args[1], &args[2])) {
 579                 args[5] = tcg_swap_cond(args[5]);
 580             }
 581             /* For movcond, we canonicalize the "false" input reg to match
 582                the destination reg so that the tcg backend can implement
 583                a "move if true" operation.  */
 584             if (swap_commutative(args[0], &args[4], &args[3])) {
 585                 args[5] = tcg_invert_cond(args[5]);
 586             }
 587             break;
 588         CASE_OP_32_64(add2):
 589             swap_commutative(args[0], &args[2], &args[4]);
 590             swap_commutative(args[1], &args[3], &args[5]);
 591             break;
 592         CASE_OP_32_64(mulu2):
 593         CASE_OP_32_64(muls2):
 594             swap_commutative(args[0], &args[2], &args[3]);
 595             break;
 596         case INDEX_op_brcond2_i32:
 597             if (swap_commutative2(&args[0], &args[2])) {
 598                 args[4] = tcg_swap_cond(args[4]);
 599             }
 600             break;
 601         case INDEX_op_setcond2_i32:
 602             if (swap_commutative2(&args[1], &args[3])) {
 603                 args[5] = tcg_swap_cond(args[5]);
 604             }
 605             break;
 606         default:
 607             break;
 608         }
 609
 610         /* Simplify expressions for "shift/rot r, 0, a => movi r, 0",
 611            and "sub r, 0, a => neg r, a" case.  */
 612         switch (op) {
 613         CASE_OP_32_64(shl):
 614         CASE_OP_32_64(shr):
 615         CASE_OP_32_64(sar):
 616         CASE_OP_32_64(rotl):
 617         CASE_OP_32_64(rotr):
 618             if (temps[args[1]].state == TCG_TEMP_CONST
 619                 && temps[args[1]].val == 0) {
 620                 s->gen_opc_buf[op_index] = op_to_movi(op);
 621                 tcg_opt_gen_movi(gen_args, args[0], 0);
 622                 args += 3;
 623                 gen_args += 2;
 624                 continue;
 625             }
 626             break;
 627         CASE_OP_32_64(sub):
 628             {
 629                 TCGOpcode neg_op;
 630                 bool have_neg;
 631
 632                 if (temps[args[2]].state == TCG_TEMP_CONST) {
 633                     /* Proceed with possible constant folding. */
 634                     break;
 635                 }
 636                 if (op == INDEX_op_sub_i32) {
 637                     neg_op = INDEX_op_neg_i32;
 638                     have_neg = TCG_TARGET_HAS_neg_i32;
 639                 } else {
 640                     neg_op = INDEX_op_neg_i64;
 641                     have_neg = TCG_TARGET_HAS_neg_i64;
 642                 }
 643                 if (!have_neg) {
 644                     break;
 645                 }
 646                 if (temps[args[1]].state == TCG_TEMP_CONST
 647                     && temps[args[1]].val == 0) {
 648                     s->gen_opc_buf[op_index] = neg_op;
 649                     reset_temp(args[0]);
 650                     gen_args[0] = args[0];
 651                     gen_args[1] = args[2];
 652                     args += 3;
 653                     gen_args += 2;
 654                     continue;
 655                 }
 656             }
 657             break;
 658         CASE_OP_32_64(xor):
 659         CASE_OP_32_64(nand):
 660             if (temps[args[1]].state != TCG_TEMP_CONST
 661                 && temps[args[2]].state == TCG_TEMP_CONST
 662                 && temps[args[2]].val == -1) {
 663                 i = 1;
 664                 goto try_not;
 665             }
 666             break;
 667         CASE_OP_32_64(nor):
 668             if (temps[args[1]].state != TCG_TEMP_CONST
 669                 && temps[args[2]].state == TCG_TEMP_CONST
 670                 && temps[args[2]].val == 0) {
 671                 i = 1;
 672                 goto try_not;
 673             }
 674             break;
 675         CASE_OP_32_64(andc):
 676             if (temps[args[2]].state != TCG_TEMP_CONST
 677                 && temps[args[1]].state == TCG_TEMP_CONST
 678                 && temps[args[1]].val == -1) {
 679                 i = 2;
 680                 goto try_not;
 681             }
 682             break;
 683         CASE_OP_32_64(orc):
 684         CASE_OP_32_64(eqv):
 685             if (temps[args[2]].state != TCG_TEMP_CONST
 686                 && temps[args[1]].state == TCG_TEMP_CONST
 687                 && temps[args[1]].val == 0) {
 688                 i = 2;
 689                 goto try_not;
 690             }
 691             break;
 692         try_not:
 693             {
 694                 TCGOpcode not_op;
 695                 bool have_not;
 696
 697                 if (def->flags & TCG_OPF_64BIT) {
 698                     not_op = INDEX_op_not_i64;
 699                     have_not = TCG_TARGET_HAS_not_i64;
 700                 } else {
 701                     not_op = INDEX_op_not_i32;
 702                     have_not = TCG_TARGET_HAS_not_i32;
 703                 }
 704                 if (!have_not) {
 705                     break;
 706                 }
 707                 s->gen_opc_buf[op_index] = not_op;
 708                 reset_temp(args[0]);
 709                 gen_args[0] = args[0];
 710                 gen_args[1] = args[i];
 711                 args += 3;
 712                 gen_args += 2;
 713                 continue;
 714             }
 715         default:
 716             break;
 717         }
 718
 719         /* Simplify expression for "op r, a, const => mov r, a" cases */
 720         switch (op) {
 721         CASE_OP_32_64(add):
 722         CASE_OP_32_64(sub):
 723         CASE_OP_32_64(shl):
 724         CASE_OP_32_64(shr):
 725         CASE_OP_32_64(sar):
 726         CASE_OP_32_64(rotl):
 727         CASE_OP_32_64(rotr):
 728         CASE_OP_32_64(or):
 729         CASE_OP_32_64(xor):
 730         CASE_OP_32_64(andc):
 731             if (temps[args[1]].state != TCG_TEMP_CONST
 732                 && temps[args[2]].state == TCG_TEMP_CONST
 733                 && temps[args[2]].val == 0) {
 734                 goto do_mov3;
 735             }
 736             break;
 737         CASE_OP_32_64(and):
 738         CASE_OP_32_64(orc):
 739         CASE_OP_32_64(eqv):
 740             if (temps[args[1]].state != TCG_TEMP_CONST
 741                 && temps[args[2]].state == TCG_TEMP_CONST
 742                 && temps[args[2]].val == -1) {
 743                 goto do_mov3;
 744             }
 745             break;
 746         do_mov3:
 747             if (temps_are_copies(args[0], args[1])) {
 748                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 749             } else {
 750                 s->gen_opc_buf[op_index] = op_to_mov(op);
 751                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 752                 gen_args += 2;
 753             }
 754             args += 3;
 755             continue;
 756         default:
 757             break;
 758         }
 759
 760         /* Simplify using known-zero bits. Currently only ops with a single
 761            output argument is supported. */
 762         mask = -1;
 763         affected = -1;
 764         switch (op) {
 765         CASE_OP_32_64(ext8s):
 766             if ((temps[args[1]].mask & 0x80) != 0) {
 767                 break;
 768             }
 769         CASE_OP_32_64(ext8u):
 770             mask = 0xff;
 771             goto and_const;
 772         CASE_OP_32_64(ext16s):
 773             if ((temps[args[1]].mask & 0x8000) != 0) {
 774                 break;
 775             }
 776         CASE_OP_32_64(ext16u):
 777             mask = 0xffff;
 778             goto and_const;
 779         case INDEX_op_ext32s_i64:
 780             if ((temps[args[1]].mask & 0x80000000) != 0) {
 781                 break;
 782             }
 783         case INDEX_op_ext32u_i64:
 784             mask = 0xffffffffU;
 785             goto and_const;
 786
 787         CASE_OP_32_64(and):
 788             mask = temps[args[2]].mask;
 789             if (temps[args[2]].state == TCG_TEMP_CONST) {
 790         and_const:
 791                 affected = temps[args[1]].mask & ~mask;
 792             }
 793             mask = temps[args[1]].mask & mask;
 794             break;
 795
 796         CASE_OP_32_64(andc):
 797             /* Known-zeros does not imply known-ones.  Therefore unless
 798                args[2] is constant, we can't infer anything from it.  */
 799             if (temps[args[2]].state == TCG_TEMP_CONST) {
 800                 mask = ~temps[args[2]].mask;
 801                 goto and_const;
 802             }
 803             /* But we certainly know nothing outside args[1] may be set. */
 804             mask = temps[args[1]].mask;
 805             break;
 806
 807         case INDEX_op_sar_i32:
 808             if (temps[args[2]].state == TCG_TEMP_CONST) {
 809                 mask = (int32_t)temps[args[1]].mask >> temps[args[2]].val;
 810             }
 811             break;
 812         case INDEX_op_sar_i64:
 813             if (temps[args[2]].state == TCG_TEMP_CONST) {
 814                 mask = (int64_t)temps[args[1]].mask >> temps[args[2]].val;
 815             }
 816             break;
 817
 818         case INDEX_op_shr_i32:
 819             if (temps[args[2]].state == TCG_TEMP_CONST) {
 820                 mask = (uint32_t)temps[args[1]].mask >> temps[args[2]].val;
 821             }
 822             break;
 823         case INDEX_op_shr_i64:
 824             if (temps[args[2]].state == TCG_TEMP_CONST) {
 825                 mask = (uint64_t)temps[args[1]].mask >> temps[args[2]].val;
 826             }
 827             break;
 828
 829         CASE_OP_32_64(shl):
 830             if (temps[args[2]].state == TCG_TEMP_CONST) {
 831                 mask = temps[args[1]].mask << temps[args[2]].val;
 832             }
 833             break;
 834
 835         CASE_OP_32_64(neg):
 836             /* Set to 1 all bits to the left of the rightmost.  */
 837             mask = -(temps[args[1]].mask & -temps[args[1]].mask);
 838             break;
 839
 840         CASE_OP_32_64(deposit):
 841             tmp = ((1ull << args[4]) - 1);
 842             mask = ((temps[args[1]].mask & ~(tmp << args[3]))
 843                     | ((temps[args[2]].mask & tmp) << args[3]));
 844             break;
 845
 846         CASE_OP_32_64(or):
 847         CASE_OP_32_64(xor):
 848             mask = temps[args[1]].mask | temps[args[2]].mask;
 849             break;
 850
 851         CASE_OP_32_64(setcond):
 852             mask = 1;
 853             break;
 854
 855         CASE_OP_32_64(movcond):
 856             mask = temps[args[3]].mask | temps[args[4]].mask;
 857             break;
 858
 859         CASE_OP_32_64(ld8u):
 860         case INDEX_op_qemu_ld8u:
 861             mask = 0xff;
 862             break;
 863         CASE_OP_32_64(ld16u):
 864         case INDEX_op_qemu_ld16u:
 865             mask = 0xffff;
 866             break;
 867         case INDEX_op_ld32u_i64:
 868 #if TCG_TARGET_REG_BITS == 64
 869         case INDEX_op_qemu_ld32u:
 870 #endif
 871             mask = 0xffffffffu;
 872             break;
 873
 874         CASE_OP_32_64(qemu_ld):
 875             {
 876                 TCGMemOp mop = args[def->nb_oargs + def->nb_iargs];
 877                 if (!(mop & MO_SIGN)) {
 878                     mask = (2ULL << ((8 << (mop & MO_SIZE)) - 1)) - 1;
 879                 }
 880             }
 881             break;
 882
 883         default:
 884             break;
 885         }
 886
 887         /* 32-bit ops (non 64-bit ops and non load/store ops) generate 32-bit
 888            results */
 889         if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_64BIT))) {
 890             mask &= 0xffffffffu;
 891         }
 892
 893         if (mask == 0) {
 894             assert(def->nb_oargs == 1);
 895             s->gen_opc_buf[op_index] = op_to_movi(op);
 896             tcg_opt_gen_movi(gen_args, args[0], 0);
 897             args += def->nb_oargs + def->nb_iargs + def->nb_cargs;
 898             gen_args += 2;
 899             continue;
 900         }
 901         if (affected == 0) {
 902             assert(def->nb_oargs == 1);
 903             if (temps_are_copies(args[0], args[1])) {
 904                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 905             } else if (temps[args[1]].state != TCG_TEMP_CONST) {
 906                 s->gen_opc_buf[op_index] = op_to_mov(op);
 907                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 908                 gen_args += 2;
 909             } else {
 910                 s->gen_opc_buf[op_index] = op_to_movi(op);
 911                 tcg_opt_gen_movi(gen_args, args[0], temps[args[1]].val);
 912                 gen_args += 2;
 913             }
 914             args += def->nb_iargs + 1;
 915             continue;
 916         }
 917
 918         /* Simplify expression for "op r, a, 0 => movi r, 0" cases */
 919         switch (op) {
 920         CASE_OP_32_64(and):
 921         CASE_OP_32_64(mul):
 922         CASE_OP_32_64(muluh):
 923         CASE_OP_32_64(mulsh):
 924             if ((temps[args[2]].state == TCG_TEMP_CONST
 925                 && temps[args[2]].val == 0)) {
 926                 s->gen_opc_buf[op_index] = op_to_movi(op);
 927                 tcg_opt_gen_movi(gen_args, args[0], 0);
 928                 args += 3;
 929                 gen_args += 2;
 930                 continue;
 931             }
 932             break;
 933         default:
 934             break;
 935         }
 936
 937         /* Simplify expression for "op r, a, a => mov r, a" cases */
 938         switch (op) {
 939         CASE_OP_32_64(or):
 940         CASE_OP_32_64(and):
 941             if (temps_are_copies(args[1], args[2])) {
 942                 if (temps_are_copies(args[0], args[1])) {
 943                     s->gen_opc_buf[op_index] = INDEX_op_nop;
 944                 } else {
 945                     s->gen_opc_buf[op_index] = op_to_mov(op);
 946                     tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 947                     gen_args += 2;
 948                 }
 949                 args += 3;
 950                 continue;
 951             }
 952             break;
 953         default:
 954             break;
 955         }
 956
 957         /* Simplify expression for "op r, a, a => movi r, 0" cases */
 958         switch (op) {
 959         CASE_OP_32_64(andc):
 960         CASE_OP_32_64(sub):
 961         CASE_OP_32_64(xor):
 962             if (temps_are_copies(args[1], args[2])) {
 963                 s->gen_opc_buf[op_index] = op_to_movi(op);
 964                 tcg_opt_gen_movi(gen_args, args[0], 0);
 965                 gen_args += 2;
 966                 args += 3;
 967                 continue;
 968             }
 969             break;
 970         default:
 971             break;
 972         }
 973
 974         /* Propagate constants through copy operations and do constant
 975            folding.  Constants will be substituted to arguments by register
 976            allocator where needed and possible.  Also detect copies. */
 977         switch (op) {
 978         CASE_OP_32_64(mov):
 979             if (temps_are_copies(args[0], args[1])) {
 980                 args += 2;
 981                 s->gen_opc_buf[op_index] = INDEX_op_nop;
 982                 break;
 983             }
 984             if (temps[args[1]].state != TCG_TEMP_CONST) {
 985                 tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
 986                 gen_args += 2;
 987                 args += 2;
 988                 break;
 989             }
 990             /* Source argument is constant.  Rewrite the operation and
 991                let movi case handle it. */
 992             op = op_to_movi(op);
 993             s->gen_opc_buf[op_index] = op;
 994             args[1] = temps[args[1]].val;
 995             /* fallthrough */
 996         CASE_OP_32_64(movi):
 997             tcg_opt_gen_movi(gen_args, args[0], args[1]);
 998             gen_args += 2;
 999             args += 2;
1000             break;
1001
1002         CASE_OP_32_64(not):
1003         CASE_OP_32_64(neg):
1004         CASE_OP_32_64(ext8s):
1005         CASE_OP_32_64(ext8u):
1006         CASE_OP_32_64(ext16s):
1007         CASE_OP_32_64(ext16u):
1008         case INDEX_op_ext32s_i64:
1009         case INDEX_op_ext32u_i64:
1010             if (temps[args[1]].state == TCG_TEMP_CONST) {
1011                 s->gen_opc_buf[op_index] = op_to_movi(op);
1012                 tmp = do_constant_folding(op, temps[args[1]].val, 0);
1013                 tcg_opt_gen_movi(gen_args, args[0], tmp);
1014                 gen_args += 2;
1015                 args += 2;
1016                 break;
1017             }
1018             goto do_default;
1019
1020         CASE_OP_32_64(add):
1021         CASE_OP_32_64(sub):
1022         CASE_OP_32_64(mul):
1023         CASE_OP_32_64(or):
1024         CASE_OP_32_64(and):
1025         CASE_OP_32_64(xor):
1026         CASE_OP_32_64(shl):
1027         CASE_OP_32_64(shr):
1028         CASE_OP_32_64(sar):
1029         CASE_OP_32_64(rotl):
1030         CASE_OP_32_64(rotr):
1031         CASE_OP_32_64(andc):
1032         CASE_OP_32_64(orc):
1033         CASE_OP_32_64(eqv):
1034         CASE_OP_32_64(nand):
1035         CASE_OP_32_64(nor):
1036         CASE_OP_32_64(muluh):
1037         CASE_OP_32_64(mulsh):
1038         CASE_OP_32_64(div):
1039         CASE_OP_32_64(divu):
1040         CASE_OP_32_64(rem):
1041         CASE_OP_32_64(remu):
1042             if (temps[args[1]].state == TCG_TEMP_CONST
1043                 && temps[args[2]].state == TCG_TEMP_CONST) {
1044                 s->gen_opc_buf[op_index] = op_to_movi(op);
1045                 tmp = do_constant_folding(op, temps[args[1]].val,
1046                                           temps[args[2]].val);
1047                 tcg_opt_gen_movi(gen_args, args[0], tmp);
1048                 gen_args += 2;
1049                 args += 3;
1050                 break;
1051             }
1052             goto do_default;
1053
1054         CASE_OP_32_64(deposit):
1055             if (temps[args[1]].state == TCG_TEMP_CONST
1056                 && temps[args[2]].state == TCG_TEMP_CONST) {
1057                 s->gen_opc_buf[op_index] = op_to_movi(op);
1058                 tmp = ((1ull << args[4]) - 1);
1059                 tmp = (temps[args[1]].val & ~(tmp << args[3]))
1060                       | ((temps[args[2]].val & tmp) << args[3]);
1061                 tcg_opt_gen_movi(gen_args, args[0], tmp);
1062                 gen_args += 2;
1063                 args += 5;
1064                 break;
1065             }
1066             goto do_default;
1067
1068         CASE_OP_32_64(setcond):
1069             tmp = do_constant_folding_cond(op, args[1], args[2], args[3]);
1070             if (tmp != 2) {
1071                 s->gen_opc_buf[op_index] = op_to_movi(op);
1072                 tcg_opt_gen_movi(gen_args, args[0], tmp);
1073                 gen_args += 2;
1074                 args += 4;
1075                 break;
1076             }
1077             goto do_default;
1078
1079         CASE_OP_32_64(brcond):
1080             tmp = do_constant_folding_cond(op, args[0], args[1], args[2]);
1081             if (tmp != 2) {
1082                 if (tmp) {
1083                     reset_all_temps(nb_temps);
1084                     s->gen_opc_buf[op_index] = INDEX_op_br;
1085                     gen_args[0] = args[3];
1086                     gen_args += 1;
1087                 } else {
1088                     s->gen_opc_buf[op_index] = INDEX_op_nop;
1089                 }
1090                 args += 4;
1091                 break;
1092             }
1093             goto do_default;
1094
1095         CASE_OP_32_64(movcond):
1096             tmp = do_constant_folding_cond(op, args[1], args[2], args[5]);
1097             if (tmp != 2) {
1098                 if (temps_are_copies(args[0], args[4-tmp])) {
1099                     s->gen_opc_buf[op_index] = INDEX_op_nop;
1100                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
1101                     s->gen_opc_buf[op_index] = op_to_movi(op);
1102                     tcg_opt_gen_movi(gen_args, args[0], temps[args[4-tmp]].val);
1103                     gen_args += 2;
1104                 } else {
1105                     s->gen_opc_buf[op_index] = op_to_mov(op);
1106                     tcg_opt_gen_mov(s, gen_args, args[0], args[4-tmp]);
1107                     gen_args += 2;
1108                 }
1109                 args += 6;
1110                 break;
1111             }
1112             goto do_default;
1113
1114         case INDEX_op_add2_i32:
1115         case INDEX_op_sub2_i32:
1116             if (temps[args[2]].state == TCG_TEMP_CONST
1117                 && temps[args[3]].state == TCG_TEMP_CONST
1118                 && temps[args[4]].state == TCG_TEMP_CONST
1119                 && temps[args[5]].state == TCG_TEMP_CONST) {
1120                 uint32_t al = temps[args[2]].val;
1121                 uint32_t ah = temps[args[3]].val;
1122                 uint32_t bl = temps[args[4]].val;
1123                 uint32_t bh = temps[args[5]].val;
1124                 uint64_t a = ((uint64_t)ah << 32) | al;
1125                 uint64_t b = ((uint64_t)bh << 32) | bl;
1126                 TCGArg rl, rh;
1127
1128                 if (op == INDEX_op_add2_i32) {
1129                     a += b;
1130                 } else {
1131                     a -= b;
1132                 }
1133
1134                 /* We emit the extra nop when we emit the add2/sub2.  */
1135                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
1136
1137                 rl = args[0];
1138                 rh = args[1];
1139                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
1140                 s->gen_opc_buf[++op_index] = INDEX_op_movi_i32;
1141                 tcg_opt_gen_movi(&gen_args[0], rl, (uint32_t)a);
1142                 tcg_opt_gen_movi(&gen_args[2], rh, (uint32_t)(a >> 32));
1143                 gen_args += 4;
1144                 args += 6;
1145                 break;
1146             }
1147             goto do_default;
1148
1149         case INDEX_op_mulu2_i32:
1150             if (temps[args[2]].state == TCG_TEMP_CONST
1151                 && temps[args[3]].state == TCG_TEMP_CONST) {
1152                 uint32_t a = temps[args[2]].val;
1153                 uint32_t b = temps[args[3]].val;
1154                 uint64_t r = (uint64_t)a * b;
1155                 TCGArg rl, rh;
1156
1157                 /* We emit the extra nop when we emit the mulu2.  */
1158                 assert(s->gen_opc_buf[op_index + 1] == INDEX_op_nop);
1159
1160                 rl = args[0];
1161                 rh = args[1];
1162                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
1163                 s->gen_opc_buf[++op_index] = INDEX_op_movi_i32;
1164                 tcg_opt_gen_movi(&gen_args[0], rl, (uint32_t)r);
1165                 tcg_opt_gen_movi(&gen_args[2], rh, (uint32_t)(r >> 32));
1166                 gen_args += 4;
1167                 args += 4;
1168                 break;
1169             }
1170             goto do_default;
1171
1172         case INDEX_op_brcond2_i32:
1173             tmp = do_constant_folding_cond2(&args[0], &args[2], args[4]);
1174             if (tmp != 2) {
1175                 if (tmp) {
1176                     reset_all_temps(nb_temps);
1177                     s->gen_opc_buf[op_index] = INDEX_op_br;
1178                     gen_args[0] = args[5];
1179                     gen_args += 1;
1180                 } else {
1181                     s->gen_opc_buf[op_index] = INDEX_op_nop;
1182                 }
1183             } else if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
1184                        && temps[args[2]].state == TCG_TEMP_CONST
1185                        && temps[args[3]].state == TCG_TEMP_CONST
1186                        && temps[args[2]].val == 0
1187                        && temps[args[3]].val == 0) {
1188                 /* Simplify LT/GE comparisons vs zero to a single compare
1189                    vs the high word of the input.  */
1190                 reset_all_temps(nb_temps);
1191                 s->gen_opc_buf[op_index] = INDEX_op_brcond_i32;
1192                 gen_args[0] = args[1];
1193                 gen_args[1] = args[3];
1194                 gen_args[2] = args[4];
1195                 gen_args[3] = args[5];
1196                 gen_args += 4;
1197             } else {
1198                 goto do_default;
1199             }
1200             args += 6;
1201             break;
1202
1203         case INDEX_op_setcond2_i32:
1204             tmp = do_constant_folding_cond2(&args[1], &args[3], args[5]);
1205             if (tmp != 2) {
1206                 s->gen_opc_buf[op_index] = INDEX_op_movi_i32;
1207                 tcg_opt_gen_movi(gen_args, args[0], tmp);
1208                 gen_args += 2;
1209             } else if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
1210                        && temps[args[3]].state == TCG_TEMP_CONST
1211                        && temps[args[4]].state == TCG_TEMP_CONST
1212                        && temps[args[3]].val == 0
1213                        && temps[args[4]].val == 0) {
1214                 /* Simplify LT/GE comparisons vs zero to a single compare
1215                    vs the high word of the input.  */
1216                 s->gen_opc_buf[op_index] = INDEX_op_setcond_i32;
1217                 reset_temp(args[0]);
1218                 gen_args[0] = args[0];
1219                 gen_args[1] = args[2];
1220                 gen_args[2] = args[4];
1221                 gen_args[3] = args[5];
1222                 gen_args += 4;
1223             } else {
1224                 goto do_default;
1225             }
1226             args += 6;
1227             break;
1228
1229         case INDEX_op_call:
1230             nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
1231             if (!(args[nb_call_args + 1] & (TCG_CALL_NO_READ_GLOBALS |
1232                                             TCG_CALL_NO_WRITE_GLOBALS))) {
1233                 for (i = 0; i < nb_globals; i++) {
1234                     reset_temp(i);
1235                 }
1236             }
1237             for (i = 0; i < (args[0] >> 16); i++) {
1238                 reset_temp(args[i + 1]);
1239             }
1240             i = nb_call_args + 3;
1241             while (i) {
1242                 *gen_args = *args;
1243                 args++;
1244                 gen_args++;
1245                 i--;
1246             }
1247             break;
1248
1249         default:
1250         do_default:
1251             /* Default case: we know nothing about operation (or were unable
1252                to compute the operation result) so no propagation is done.
1253                We trash everything if the operation is the end of a basic
1254                block, otherwise we only trash the output args.  "mask" is
1255                the non-zero bits mask for the first output arg.  */
1256             if (def->flags & TCG_OPF_BB_END) {
1257                 reset_all_temps(nb_temps);
1258             } else {
1259                 for (i = 0; i < def->nb_oargs; i++) {
1260                     reset_temp(args[i]);
1261                     /* Save the corresponding known-zero bits mask for the
1262                        first output argument (only one supported so far). */
1263                     if (i == 0) {
1264                         temps[args[i]].mask = mask;
1265                     }
1266                 }
1267             }
1268             for (i = 0; i < def->nb_args; i++) {
1269                 gen_args[i] = args[i];
1270             }
1271             args += def->nb_args;
1272             gen_args += def->nb_args;
1273             break;
1274         }
1275     }
1276
1277     return gen_args;
1278 }
1279
1280 TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
1281         TCGArg *args, TCGOpDef *tcg_op_defs)
1282 {
1283     TCGArg *res;
1284     res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
1285     return res;
1286 }