src/lcode.c

   1 /*
   2 ** $Id: lcode.c,v 2.25 2006/03/21 19:28:49 roberto Exp $
   3 ** Code generator for Lua
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stdlib.h>
   9
  10 #define lcode_c
  11 #define LUA_CORE
  12
  13 #include "lua.h"
  14
  15 #include "lcode.h"
  16 #include "ldebug.h"
  17 #include "ldo.h"
  18 #include "lgc.h"
  19 #include "llex.h"
  20 #include "lmem.h"
  21 #include "lobject.h"
  22 #include "lopcodes.h"
  23 #include "lparser.h"
  24 #include "ltable.h"
  25
  26
  27 #define hasjumps(e)     ((e)->t != (e)->f)
  28
  29
  30 static int isnumeral(expdesc *e) {
  31   return (e->k == VKNUM && e->t == NO_JUMP && e->f == NO_JUMP);
  32 }
  33
  34
  35 void luaK_nil (FuncState *fs, int from, int n) {
  36   Instruction *previous;
  37   if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
  38     if (fs->pc == 0)  /* function start? */
  39       return;  /* positions are already clean */
  40     if (GET_OPCODE(*(previous = &fs->f->code[fs->pc-1])) == OP_LOADNIL) {
  41       int pfrom = GETARG_A(*previous);
  42       int pto = GETARG_B(*previous);
  43       if (pfrom <= from && from <= pto+1) {  /* can connect both? */
  44         if (from+n-1 > pto)
  45           SETARG_B(*previous, from+n-1);
  46         return;
  47       }
  48     }
  49   }
  50   luaK_codeABC(fs, OP_LOADNIL, from, from+n-1, 0);  /* else no optimization */
  51 }
  52
  53
  54 int luaK_jump (FuncState *fs) {
  55   int jpc = fs->jpc;  /* save list of jumps to here */
  56   int j;
  57   fs->jpc = NO_JUMP;
  58   j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
  59   luaK_concat(fs, &j, jpc);  /* keep them on hold */
  60   return j;
  61 }
  62
  63
  64 void luaK_ret (FuncState *fs, int first, int nret) {
  65   luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
  66 }
  67
  68
  69 static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
  70   luaK_codeABC(fs, op, A, B, C);
  71   return luaK_jump(fs);
  72 }
  73
  74
  75 static void fixjump (FuncState *fs, int pc, int dest) {
  76   Instruction *jmp = &fs->f->code[pc];
  77   int offset = dest-(pc+1);
  78   lua_assert(dest != NO_JUMP);
  79   if (abs(offset) > MAXARG_sBx)
  80     luaX_syntaxerror(fs->ls, "control structure too long");
  81   SETARG_sBx(*jmp, offset);
  82 }
  83
  84
  85 /*
  86 ** returns current `pc' and marks it as a jump target (to avoid wrong
  87 ** optimizations with consecutive instructions not in the same basic block).
  88 */
  89 int luaK_getlabel (FuncState *fs) {
  90   fs->lasttarget = fs->pc;
  91   return fs->pc;
  92 }
  93
  94
  95 static int getjump (FuncState *fs, int pc) {
  96   int offset = GETARG_sBx(fs->f->code[pc]);
  97   if (offset == NO_JUMP)  /* point to itself represents end of list */
  98     return NO_JUMP;  /* end of list */
  99   else
 100     return (pc+1)+offset;  /* turn offset into absolute position */
 101 }
 102
 103
 104 static Instruction *getjumpcontrol (FuncState *fs, int pc) {
 105   Instruction *pi = &fs->f->code[pc];
 106   if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
 107     return pi-1;
 108   else
 109     return pi;
 110 }
 111
 112
 113 /*
 114 ** check whether list has any jump that do not produce a value
 115 ** (or produce an inverted value)
 116 */
 117 static int need_value (FuncState *fs, int list) {
 118   for (; list != NO_JUMP; list = getjump(fs, list)) {
 119     Instruction i = *getjumpcontrol(fs, list);
 120     if (GET_OPCODE(i) != OP_TESTSET) return 1;
 121   }
 122   return 0;  /* not found */
 123 }
 124
 125
 126 static int patchtestreg (FuncState *fs, int node, int reg) {
 127   Instruction *i = getjumpcontrol(fs, node);
 128   if (GET_OPCODE(*i) != OP_TESTSET)
 129     return 0;  /* cannot patch other instructions */
 130   if (reg != NO_REG && reg != GETARG_B(*i))
 131     SETARG_A(*i, reg);
 132   else  /* no register to put value or register already has the value */
 133     *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
 134
 135   return 1;
 136 }
 137
 138
 139 static void removevalues (FuncState *fs, int list) {
 140   for (; list != NO_JUMP; list = getjump(fs, list))
 141       patchtestreg(fs, list, NO_REG);
 142 }
 143
 144
 145 static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
 146                           int dtarget) {
 147   while (list != NO_JUMP) {
 148     int next = getjump(fs, list);
 149     if (patchtestreg(fs, list, reg))
 150       fixjump(fs, list, vtarget);
 151     else
 152       fixjump(fs, list, dtarget);  /* jump to default target */
 153     list = next;
 154   }
 155 }
 156
 157
 158 static void dischargejpc (FuncState *fs) {
 159   patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
 160   fs->jpc = NO_JUMP;
 161 }
 162
 163
 164 void luaK_patchlist (FuncState *fs, int list, int target) {
 165   if (target == fs->pc)
 166     luaK_patchtohere(fs, list);
 167   else {
 168     lua_assert(target < fs->pc);
 169     patchlistaux(fs, list, target, NO_REG, target);
 170   }
 171 }
 172
 173
 174 void luaK_patchtohere (FuncState *fs, int list) {
 175   luaK_getlabel(fs);
 176   luaK_concat(fs, &fs->jpc, list);
 177 }
 178
 179
 180 void luaK_concat (FuncState *fs, int *l1, int l2) {
 181   if (l2 == NO_JUMP) return;
 182   else if (*l1 == NO_JUMP)
 183     *l1 = l2;
 184   else {
 185     int list = *l1;
 186     int next;
 187     while ((next = getjump(fs, list)) != NO_JUMP)  /* find last element */
 188       list = next;
 189     fixjump(fs, list, l2);
 190   }
 191 }
 192
 193
 194 void luaK_checkstack (FuncState *fs, int n) {
 195   int newstack = fs->freereg + n;
 196   if (newstack > fs->f->maxstacksize) {
 197     if (newstack >= MAXSTACK)
 198       luaX_syntaxerror(fs->ls, "function or expression too complex");
 199     fs->f->maxstacksize = cast_byte(newstack);
 200   }
 201 }
 202
 203
 204 void luaK_reserveregs (FuncState *fs, int n) {
 205   luaK_checkstack(fs, n);
 206   fs->freereg += n;
 207 }
 208
 209
 210 static void freereg (FuncState *fs, int reg) {
 211   if (!ISK(reg) && reg >= fs->nactvar) {
 212     fs->freereg--;
 213     lua_assert(reg == fs->freereg);
 214   }
 215 }
 216
 217
 218 static void freeexp (FuncState *fs, expdesc *e) {
 219   if (e->k == VNONRELOC)
 220     freereg(fs, e->u.s.info);
 221 }
 222
 223
 224 static int addk (FuncState *fs, TValue *k, TValue *v) {
 225   lua_State *L = fs->L;
 226   TValue *idx = luaH_set(L, fs->h, k);
 227   Proto *f = fs->f;
 228   int oldsize = f->sizek;
 229   if (ttisnumber(idx)) {
 230     lua_assert(luaO_rawequalObj(&fs->f->k[cast_int(nvalue(idx))], v));
 231     return cast_int(nvalue(idx));
 232   }
 233   else {  /* constant not found; create a new entry */
 234     setnvalue(idx, cast_num(fs->nk));
 235     luaM_growvector(L, f->k, fs->nk, f->sizek, TValue,
 236                     MAXARG_Bx, "constant table overflow");
 237     while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
 238     setobj(L, &f->k[fs->nk], v);
 239     luaC_barrier(L, f, v);
 240     return fs->nk++;
 241   }
 242 }
 243
 244
 245 int luaK_stringK (FuncState *fs, TString *s) {
 246   TValue o;
 247   setsvalue(fs->L, &o, s);
 248   return addk(fs, &o, &o);
 249 }
 250
 251
 252 int luaK_numberK (FuncState *fs, lua_Number r) {
 253   TValue o;
 254   setnvalue(&o, r);
 255   return addk(fs, &o, &o);
 256 }
 257
 258
 259 static int boolK (FuncState *fs, int b) {
 260   TValue o;
 261   setbvalue(&o, b);
 262   return addk(fs, &o, &o);
 263 }
 264
 265
 266 static int nilK (FuncState *fs) {
 267   TValue k, v;
 268   setnilvalue(&v);
 269   /* cannot use nil as key; instead use table itself to represent nil */
 270   sethvalue(fs->L, &k, fs->h);
 271   return addk(fs, &k, &v);
 272 }
 273
 274
 275 void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
 276   if (e->k == VCALL) {  /* expression is an open function call? */
 277     SETARG_C(getcode(fs, e), nresults+1);
 278   }
 279   else if (e->k == VVARARG) {
 280     SETARG_B(getcode(fs, e), nresults+1);
 281     SETARG_A(getcode(fs, e), fs->freereg);
 282     luaK_reserveregs(fs, 1);
 283   }
 284 }
 285
 286
 287 void luaK_setoneret (FuncState *fs, expdesc *e) {
 288   if (e->k == VCALL) {  /* expression is an open function call? */
 289     e->k = VNONRELOC;
 290     e->u.s.info = GETARG_A(getcode(fs, e));
 291   }
 292   else if (e->k == VVARARG) {
 293     SETARG_B(getcode(fs, e), 2);
 294     e->k = VRELOCABLE;  /* can relocate its simple result */
 295   }
 296 }
 297
 298
 299 void luaK_dischargevars (FuncState *fs, expdesc *e) {
 300   switch (e->k) {
 301     case VLOCAL: {
 302       e->k = VNONRELOC;
 303       break;
 304     }
 305     case VUPVAL: {
 306       e->u.s.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.s.info, 0);
 307       e->k = VRELOCABLE;
 308       break;
 309     }
 310     case VGLOBAL: {
 311       e->u.s.info = luaK_codeABx(fs, OP_GETGLOBAL, 0, e->u.s.info);
 312       e->k = VRELOCABLE;
 313       break;
 314     }
 315     case VINDEXED: {
 316       freereg(fs, e->u.s.aux);
 317       freereg(fs, e->u.s.info);
 318       e->u.s.info = luaK_codeABC(fs, OP_GETTABLE, 0, e->u.s.info, e->u.s.aux);
 319       e->k = VRELOCABLE;
 320       break;
 321     }
 322     case VVARARG:
 323     case VCALL: {
 324       luaK_setoneret(fs, e);
 325       break;
 326     }
 327     default: break;  /* there is one value available (somewhere) */
 328   }
 329 }
 330
 331
 332 static int code_label (FuncState *fs, int A, int b, int jump) {
 333   luaK_getlabel(fs);  /* those instructions may be jump targets */
 334   return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
 335 }
 336
 337
 338 static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
 339   luaK_dischargevars(fs, e);
 340   switch (e->k) {
 341     case VNIL: {
 342       luaK_nil(fs, reg, 1);
 343       break;
 344     }
 345     case VFALSE:  case VTRUE: {
 346       luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
 347       break;
 348     }
 349     case VK: {
 350       luaK_codeABx(fs, OP_LOADK, reg, e->u.s.info);
 351       break;
 352     }
 353     case VKNUM: {
 354       luaK_codeABx(fs, OP_LOADK, reg, luaK_numberK(fs, e->u.nval));
 355       break;
 356     }
 357     case VRELOCABLE: {
 358       Instruction *pc = &getcode(fs, e);
 359       SETARG_A(*pc, reg);
 360       break;
 361     }
 362     case VNONRELOC: {
 363       if (reg != e->u.s.info)
 364         luaK_codeABC(fs, OP_MOVE, reg, e->u.s.info, 0);
 365       break;
 366     }
 367     default: {
 368       lua_assert(e->k == VVOID || e->k == VJMP);
 369       return;  /* nothing to do... */
 370     }
 371   }
 372   e->u.s.info = reg;
 373   e->k = VNONRELOC;
 374 }
 375
 376
 377 static void discharge2anyreg (FuncState *fs, expdesc *e) {
 378   if (e->k != VNONRELOC) {
 379     luaK_reserveregs(fs, 1);
 380     discharge2reg(fs, e, fs->freereg-1);
 381   }
 382 }
 383
 384
 385 static void exp2reg (FuncState *fs, expdesc *e, int reg) {
 386   discharge2reg(fs, e, reg);
 387   if (e->k == VJMP)
 388     luaK_concat(fs, &e->t, e->u.s.info);  /* put this jump in `t' list */
 389   if (hasjumps(e)) {
 390     int final;  /* position after whole expression */
 391     int p_f = NO_JUMP;  /* position of an eventual LOAD false */
 392     int p_t = NO_JUMP;  /* position of an eventual LOAD true */
 393     if (need_value(fs, e->t) || need_value(fs, e->f)) {
 394       int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
 395       p_f = code_label(fs, reg, 0, 1);
 396       p_t = code_label(fs, reg, 1, 0);
 397       luaK_patchtohere(fs, fj);
 398     }
 399     final = luaK_getlabel(fs);
 400     patchlistaux(fs, e->f, final, reg, p_f);
 401     patchlistaux(fs, e->t, final, reg, p_t);
 402   }
 403   e->f = e->t = NO_JUMP;
 404   e->u.s.info = reg;
 405   e->k = VNONRELOC;
 406 }
 407
 408
 409 void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
 410   luaK_dischargevars(fs, e);
 411   freeexp(fs, e);
 412   luaK_reserveregs(fs, 1);
 413   exp2reg(fs, e, fs->freereg - 1);
 414 }
 415
 416
 417 int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
 418   luaK_dischargevars(fs, e);
 419   if (e->k == VNONRELOC) {
 420     if (!hasjumps(e)) return e->u.s.info;  /* exp is already in a register */
 421     if (e->u.s.info >= fs->nactvar) {  /* reg. is not a local? */
 422       exp2reg(fs, e, e->u.s.info);  /* put value on it */
 423       return e->u.s.info;
 424     }
 425   }
 426   luaK_exp2nextreg(fs, e);  /* default */
 427   return e->u.s.info;
 428 }
 429
 430
 431 void luaK_exp2val (FuncState *fs, expdesc *e) {
 432   if (hasjumps(e))
 433     luaK_exp2anyreg(fs, e);
 434   else
 435     luaK_dischargevars(fs, e);
 436 }
 437
 438
 439 int luaK_exp2RK (FuncState *fs, expdesc *e) {
 440   luaK_exp2val(fs, e);
 441   switch (e->k) {
 442     case VKNUM:
 443     case VTRUE:
 444     case VFALSE:
 445     case VNIL: {
 446       if (fs->nk <= MAXINDEXRK) {  /* constant fit in RK operand? */
 447         e->u.s.info = (e->k == VNIL)  ? nilK(fs) :
 448                       (e->k == VKNUM) ? luaK_numberK(fs, e->u.nval) :
 449                                         boolK(fs, (e->k == VTRUE));
 450         e->k = VK;
 451         return RKASK(e->u.s.info);
 452       }
 453       else break;
 454     }
 455     case VK: {
 456       if (e->u.s.info <= MAXINDEXRK)  /* constant fit in argC? */
 457         return RKASK(e->u.s.info);
 458       else break;
 459     }
 460     default: break;
 461   }
 462   /* not a constant in the right range: put it in a register */
 463   return luaK_exp2anyreg(fs, e);
 464 }
 465
 466
 467 void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
 468   switch (var->k) {
 469     case VLOCAL: {
 470       freeexp(fs, ex);
 471       exp2reg(fs, ex, var->u.s.info);
 472       return;
 473     }
 474     case VUPVAL: {
 475       int e = luaK_exp2anyreg(fs, ex);
 476       luaK_codeABC(fs, OP_SETUPVAL, e, var->u.s.info, 0);
 477       break;
 478     }
 479     case VGLOBAL: {
 480       int e = luaK_exp2anyreg(fs, ex);
 481       luaK_codeABx(fs, OP_SETGLOBAL, e, var->u.s.info);
 482       break;
 483     }
 484     case VINDEXED: {
 485       int e = luaK_exp2RK(fs, ex);
 486       luaK_codeABC(fs, OP_SETTABLE, var->u.s.info, var->u.s.aux, e);
 487       break;
 488     }
 489     default: {
 490       lua_assert(0);  /* invalid var kind to store */
 491       break;
 492     }
 493   }
 494   freeexp(fs, ex);
 495 }
 496
 497
 498 void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
 499   int func;
 500   luaK_exp2anyreg(fs, e);
 501   freeexp(fs, e);
 502   func = fs->freereg;
 503   luaK_reserveregs(fs, 2);
 504   luaK_codeABC(fs, OP_SELF, func, e->u.s.info, luaK_exp2RK(fs, key));
 505   freeexp(fs, key);
 506   e->u.s.info = func;
 507   e->k = VNONRELOC;
 508 }
 509
 510
 511 static void invertjump (FuncState *fs, expdesc *e) {
 512   Instruction *pc = getjumpcontrol(fs, e->u.s.info);
 513   lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
 514                                            GET_OPCODE(*pc) != OP_TEST);
 515   SETARG_A(*pc, !(GETARG_A(*pc)));
 516 }
 517
 518
 519 static int jumponcond (FuncState *fs, expdesc *e, int cond) {
 520   if (e->k == VRELOCABLE) {
 521     Instruction ie = getcode(fs, e);
 522     if (GET_OPCODE(ie) == OP_NOT) {
 523       fs->pc--;  /* remove previous OP_NOT */
 524       return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
 525     }
 526     /* else go through */
 527   }
 528   discharge2anyreg(fs, e);
 529   freeexp(fs, e);
 530   return condjump(fs, OP_TESTSET, NO_REG, e->u.s.info, cond);
 531 }
 532
 533
 534 void luaK_goiftrue (FuncState *fs, expdesc *e) {
 535   int pc;  /* pc of last jump */
 536   luaK_dischargevars(fs, e);
 537   switch (e->k) {
 538     case VK: case VKNUM: case VTRUE: {
 539       pc = NO_JUMP;  /* always true; do nothing */
 540       break;
 541     }
 542     case VFALSE: {
 543       pc = luaK_jump(fs);  /* always jump */
 544       break;
 545     }
 546     case VJMP: {
 547       invertjump(fs, e);
 548       pc = e->u.s.info;
 549       break;
 550     }
 551     default: {
 552       pc = jumponcond(fs, e, 0);
 553       break;
 554     }
 555   }
 556   luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
 557   luaK_patchtohere(fs, e->t);
 558   e->t = NO_JUMP;
 559 }
 560
 561
 562 static void luaK_goiffalse (FuncState *fs, expdesc *e) {
 563   int pc;  /* pc of last jump */
 564   luaK_dischargevars(fs, e);
 565   switch (e->k) {
 566     case VNIL: case VFALSE: {
 567       pc = NO_JUMP;  /* always false; do nothing */
 568       break;
 569     }
 570     case VTRUE: {
 571       pc = luaK_jump(fs);  /* always jump */
 572       break;
 573     }
 574     case VJMP: {
 575       pc = e->u.s.info;
 576       break;
 577     }
 578     default: {
 579       pc = jumponcond(fs, e, 1);
 580       break;
 581     }
 582   }
 583   luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
 584   luaK_patchtohere(fs, e->f);
 585   e->f = NO_JUMP;
 586 }
 587
 588
 589 static void codenot (FuncState *fs, expdesc *e) {
 590   luaK_dischargevars(fs, e);
 591   switch (e->k) {
 592     case VNIL: case VFALSE: {
 593       e->k = VTRUE;
 594       break;
 595     }
 596     case VK: case VKNUM: case VTRUE: {
 597       e->k = VFALSE;
 598       break;
 599     }
 600     case VJMP: {
 601       invertjump(fs, e);
 602       break;
 603     }
 604     case VRELOCABLE:
 605     case VNONRELOC: {
 606       discharge2anyreg(fs, e);
 607       freeexp(fs, e);
 608       e->u.s.info = luaK_codeABC(fs, OP_NOT, 0, e->u.s.info, 0);
 609       e->k = VRELOCABLE;
 610       break;
 611     }
 612     default: {
 613       lua_assert(0);  /* cannot happen */
 614       break;
 615     }
 616   }
 617   /* interchange true and false lists */
 618   { int temp = e->f; e->f = e->t; e->t = temp; }
 619   removevalues(fs, e->f);
 620   removevalues(fs, e->t);
 621 }
 622
 623
 624 void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
 625   t->u.s.aux = luaK_exp2RK(fs, k);
 626   t->k = VINDEXED;
 627 }
 628
 629
 630 static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
 631   lua_Number v1, v2, r;
 632   if (!isnumeral(e1) || !isnumeral(e2)) return 0;
 633   v1 = e1->u.nval;
 634   v2 = e2->u.nval;
 635   switch (op) {
 636     case OP_ADD: r = luai_numadd(v1, v2); break;
 637     case OP_SUB: r = luai_numsub(v1, v2); break;
 638     case OP_MUL: r = luai_nummul(v1, v2); break;
 639     case OP_DIV:
 640       if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
 641       r = luai_numdiv(v1, v2); break;
 642     case OP_MOD:
 643       if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
 644       r = luai_nummod(v1, v2); break;
 645     case OP_POW: r = luai_numpow(v1, v2); break;
 646     case OP_UNM: r = luai_numunm(v1); break;
 647     case OP_LEN: return 0;  /* no constant folding for 'len' */
 648     default: lua_assert(0); r = 0; break;
 649   }
 650   if (luai_numisnan(r)) return 0;  /* do not attempt to produce NaN */
 651   e1->u.nval = r;
 652   return 1;
 653 }
 654
 655
 656 static void codearith (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2) {
 657   if (constfolding(op, e1, e2))
 658     return;
 659   else {
 660     int o1 = luaK_exp2RK(fs, e1);
 661     int o2 = (op != OP_UNM && op != OP_LEN) ? luaK_exp2RK(fs, e2) : 0;
 662     freeexp(fs, e2);
 663     freeexp(fs, e1);
 664     e1->u.s.info = luaK_codeABC(fs, op, 0, o1, o2);
 665     e1->k = VRELOCABLE;
 666   }
 667 }
 668
 669
 670 static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
 671                                                           expdesc *e2) {
 672   int o1 = luaK_exp2RK(fs, e1);
 673   int o2 = luaK_exp2RK(fs, e2);
 674   freeexp(fs, e2);
 675   freeexp(fs, e1);
 676   if (cond == 0 && op != OP_EQ) {
 677     int temp;  /* exchange args to replace by `<' or `<=' */
 678     temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
 679     cond = 1;
 680   }
 681   e1->u.s.info = condjump(fs, op, cond, o1, o2);
 682   e1->k = VJMP;
 683 }
 684
 685
 686 void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e) {
 687   expdesc e2;
 688   e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
 689   switch (op) {
 690     case OPR_MINUS: {
 691       if (e->k == VK)
 692         luaK_exp2anyreg(fs, e);  /* cannot operate on non-numeric constants */
 693       codearith(fs, OP_UNM, e, &e2);
 694       break;
 695     }
 696     case OPR_NOT: codenot(fs, e); break;
 697     case OPR_LEN: {
 698       luaK_exp2anyreg(fs, e);  /* cannot operate on constants */
 699       codearith(fs, OP_LEN, e, &e2);
 700       break;
 701     }
 702     default: lua_assert(0);
 703   }
 704 }
 705
 706
 707 void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
 708   switch (op) {
 709     case OPR_AND: {
 710       luaK_goiftrue(fs, v);
 711       break;
 712     }
 713     case OPR_OR: {
 714       luaK_goiffalse(fs, v);
 715       break;
 716     }
 717     case OPR_CONCAT: {
 718       luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
 719       break;
 720     }
 721     default: {
 722       if (!isnumeral(v)) luaK_exp2RK(fs, v);
 723       break;
 724     }
 725   }
 726 }
 727
 728
 729 void luaK_posfix (FuncState *fs, BinOpr op, expdesc *e1, expdesc *e2) {
 730   switch (op) {
 731     case OPR_AND: {
 732       lua_assert(e1->t == NO_JUMP);  /* list must be closed */
 733       luaK_dischargevars(fs, e2);
 734       luaK_concat(fs, &e2->f, e1->f);
 735       *e1 = *e2;
 736       break;
 737     }
 738     case OPR_OR: {
 739       lua_assert(e1->f == NO_JUMP);  /* list must be closed */
 740       luaK_dischargevars(fs, e2);
 741       luaK_concat(fs, &e2->t, e1->t);
 742       *e1 = *e2;
 743       break;
 744     }
 745     case OPR_CONCAT: {
 746       luaK_exp2val(fs, e2);
 747       if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
 748         lua_assert(e1->u.s.info == GETARG_B(getcode(fs, e2))-1);
 749         freeexp(fs, e1);
 750         SETARG_B(getcode(fs, e2), e1->u.s.info);
 751         e1->k = VRELOCABLE; e1->u.s.info = e2->u.s.info;
 752       }
 753       else {
 754         luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
 755         codearith(fs, OP_CONCAT, e1, e2);
 756       }
 757       break;
 758     }
 759     case OPR_ADD: codearith(fs, OP_ADD, e1, e2); break;
 760     case OPR_SUB: codearith(fs, OP_SUB, e1, e2); break;
 761     case OPR_MUL: codearith(fs, OP_MUL, e1, e2); break;
 762     case OPR_DIV: codearith(fs, OP_DIV, e1, e2); break;
 763     case OPR_MOD: codearith(fs, OP_MOD, e1, e2); break;
 764     case OPR_POW: codearith(fs, OP_POW, e1, e2); break;
 765     case OPR_EQ: codecomp(fs, OP_EQ, 1, e1, e2); break;
 766     case OPR_NE: codecomp(fs, OP_EQ, 0, e1, e2); break;
 767     case OPR_LT: codecomp(fs, OP_LT, 1, e1, e2); break;
 768     case OPR_LE: codecomp(fs, OP_LE, 1, e1, e2); break;
 769     case OPR_GT: codecomp(fs, OP_LT, 0, e1, e2); break;
 770     case OPR_GE: codecomp(fs, OP_LE, 0, e1, e2); break;
 771     default: lua_assert(0);
 772   }
 773 }
 774
 775
 776 void luaK_fixline (FuncState *fs, int line) {
 777   fs->f->lineinfo[fs->pc - 1] = line;
 778 }
 779
 780
 781 static int luaK_code (FuncState *fs, Instruction i, int line) {
 782   Proto *f = fs->f;
 783   dischargejpc(fs);  /* `pc' will change */
 784   /* put new instruction in code array */
 785   luaM_growvector(fs->L, f->code, fs->pc, f->sizecode, Instruction,
 786                   MAX_INT, "code size overflow");
 787   f->code[fs->pc] = i;
 788   /* save corresponding line information */
 789   luaM_growvector(fs->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
 790                   MAX_INT, "code size overflow");
 791   f->lineinfo[fs->pc] = line;
 792   return fs->pc++;
 793 }
 794
 795
 796 int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
 797   lua_assert(getOpMode(o) == iABC);
 798   lua_assert(getBMode(o) != OpArgN || b == 0);
 799   lua_assert(getCMode(o) != OpArgN || c == 0);
 800   return luaK_code(fs, CREATE_ABC(o, a, b, c), fs->ls->lastline);
 801 }
 802
 803
 804 int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
 805   lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
 806   lua_assert(getCMode(o) == OpArgN);
 807   return luaK_code(fs, CREATE_ABx(o, a, bc), fs->ls->lastline);
 808 }
 809
 810
 811 void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
 812   int c =  (nelems - 1)/LFIELDS_PER_FLUSH + 1;
 813   int b = (tostore == LUA_MULTRET) ? 0 : tostore;
 814   lua_assert(tostore != 0);
 815   if (c <= MAXARG_C)
 816     luaK_codeABC(fs, OP_SETLIST, base, b, c);
 817   else {
 818     luaK_codeABC(fs, OP_SETLIST, base, b, 0);
 819     luaK_code(fs, cast(Instruction, c), fs->ls->lastline);
 820   }
 821   fs->freereg = base + 1;  /* free registers with list values */
 822 }
 823