lua/lcode.c

   1 /*
   2 ** $Id: lcode.c,v 2.25.1.3 2007/12/28 15:32:23 roberto Exp $
   3 ** Code generator for Lua
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #if 0
   8 #include <stdlib.h>
   9 #endif
  10
  11 #define lcode_c
  12 #define LUA_CORE
  13
  14 #include "lua.h"
  15
  16 #include "lcode.h"
  17 #include "ldebug.h"
  18 #include "ldo.h"
  19 #include "lgc.h"
  20 #include "llex.h"
  21 #include "lmem.h"
  22 #include "lobject.h"
  23 #include "lopcodes.h"
  24 #include "lparser.h"
  25 #include "ltable.h"
  26
  27
  28 #define hasjumps(e)     ((e)->t != (e)->f)
  29
  30
  31 static int isnumeral(expdesc *e) {
  32   return (e->k == VKNUM && e->t == NO_JUMP && e->f == NO_JUMP);
  33 }
  34
  35
  36 void luaK_nil (FuncState *fs, int from, int n) {
  37   Instruction *previous;
  38   if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
  39     if (fs->pc == 0) {  /* function start? */
  40       if (from >= fs->nactvar)
  41         return;  /* positions are already clean */
  42     }
  43     else {
  44       previous = &fs->f->code[fs->pc-1];
  45       if (GET_OPCODE(*previous) == OP_LOADNIL) {
  46         int pfrom = GETARG_A(*previous);
  47         int pto = GETARG_B(*previous);
  48         if (pfrom <= from && from <= pto+1) {  /* can connect both? */
  49           if (from+n-1 > pto)
  50             SETARG_B(*previous, from+n-1);
  51           return;
  52         }
  53       }
  54     }
  55   }
  56   luaK_codeABC(fs, OP_LOADNIL, from, from+n-1, 0);  /* else no optimization */
  57 }
  58
  59
  60 int luaK_jump (FuncState *fs) {
  61   int jpc = fs->jpc;  /* save list of jumps to here */
  62   int j;
  63   fs->jpc = NO_JUMP;
  64   j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
  65   luaK_concat(fs, &j, jpc);  /* keep them on hold */
  66   return j;
  67 }
  68
  69
  70 void luaK_ret (FuncState *fs, int first, int nret) {
  71   luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
  72 }
  73
  74
  75 static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
  76   luaK_codeABC(fs, op, A, B, C);
  77   return luaK_jump(fs);
  78 }
  79
  80
  81 static void fixjump (FuncState *fs, int pc, int dest) {
  82   Instruction *jmp = &fs->f->code[pc];
  83   int offset = dest-(pc+1);
  84   lua_assert(dest != NO_JUMP);
  85   if (abs(offset) > MAXARG_sBx)
  86     luaX_syntaxerror(fs->ls, "control structure too long");
  87   SETARG_sBx(*jmp, offset);
  88 }
  89
  90
  91 /*
  92 ** returns current `pc' and marks it as a jump target (to avoid wrong
  93 ** optimizations with consecutive instructions not in the same basic block).
  94 */
  95 int luaK_getlabel (FuncState *fs) {
  96   fs->lasttarget = fs->pc;
  97   return fs->pc;
  98 }
  99
 100
 101 static int getjump (FuncState *fs, int pc) {
 102   int offset = GETARG_sBx(fs->f->code[pc]);
 103   if (offset == NO_JUMP)  /* point to itself represents end of list */
 104     return NO_JUMP;  /* end of list */
 105   else
 106     return (pc+1)+offset;  /* turn offset into absolute position */
 107 }
 108
 109
 110 static Instruction *getjumpcontrol (FuncState *fs, int pc) {
 111   Instruction *pi = &fs->f->code[pc];
 112   if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
 113     return pi-1;
 114   else
 115     return pi;
 116 }
 117
 118
 119 /*
 120 ** check whether list has any jump that do not produce a value
 121 ** (or produce an inverted value)
 122 */
 123 static int need_value (FuncState *fs, int list) {
 124   for (; list != NO_JUMP; list = getjump(fs, list)) {
 125     Instruction i = *getjumpcontrol(fs, list);
 126     if (GET_OPCODE(i) != OP_TESTSET) return 1;
 127   }
 128   return 0;  /* not found */
 129 }
 130
 131
 132 static int patchtestreg (FuncState *fs, int node, int reg) {
 133   Instruction *i = getjumpcontrol(fs, node);
 134   if (GET_OPCODE(*i) != OP_TESTSET)
 135     return 0;  /* cannot patch other instructions */
 136   if (reg != NO_REG && reg != GETARG_B(*i))
 137     SETARG_A(*i, reg);
 138   else  /* no register to put value or register already has the value */
 139     *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
 140
 141   return 1;
 142 }
 143
 144
 145 static void removevalues (FuncState *fs, int list) {
 146   for (; list != NO_JUMP; list = getjump(fs, list))
 147       patchtestreg(fs, list, NO_REG);
 148 }
 149
 150
 151 static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
 152                           int dtarget) {
 153   while (list != NO_JUMP) {
 154     int next = getjump(fs, list);
 155     if (patchtestreg(fs, list, reg))
 156       fixjump(fs, list, vtarget);
 157     else
 158       fixjump(fs, list, dtarget);  /* jump to default target */
 159     list = next;
 160   }
 161 }
 162
 163
 164 static void dischargejpc (FuncState *fs) {
 165   patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
 166   fs->jpc = NO_JUMP;
 167 }
 168
 169
 170 void luaK_patchlist (FuncState *fs, int list, int target) {
 171   if (target == fs->pc)
 172     luaK_patchtohere(fs, list);
 173   else {
 174     lua_assert(target < fs->pc);
 175     patchlistaux(fs, list, target, NO_REG, target);
 176   }
 177 }
 178
 179
 180 void luaK_patchtohere (FuncState *fs, int list) {
 181   luaK_getlabel(fs);
 182   luaK_concat(fs, &fs->jpc, list);
 183 }
 184
 185
 186 void luaK_concat (FuncState *fs, int *l1, int l2) {
 187   if (l2 == NO_JUMP) return;
 188   else if (*l1 == NO_JUMP)
 189     *l1 = l2;
 190   else {
 191     int list = *l1;
 192     int next;
 193     while ((next = getjump(fs, list)) != NO_JUMP)  /* find last element */
 194       list = next;
 195     fixjump(fs, list, l2);
 196   }
 197 }
 198
 199
 200 void luaK_checkstack (FuncState *fs, int n) {
 201   int newstack = fs->freereg + n;
 202   if (newstack > fs->f->maxstacksize) {
 203     if (newstack >= MAXSTACK)
 204       luaX_syntaxerror(fs->ls, "function or expression too complex");
 205     fs->f->maxstacksize = cast_byte(newstack);
 206   }
 207 }
 208
 209
 210 void luaK_reserveregs (FuncState *fs, int n) {
 211   luaK_checkstack(fs, n);
 212   fs->freereg += n;
 213 }
 214
 215
 216 static void freereg (FuncState *fs, int reg) {
 217   if (!ISK(reg) && reg >= fs->nactvar) {
 218     fs->freereg--;
 219     lua_assert(reg == fs->freereg);
 220   }
 221 }
 222
 223
 224 static void freeexp (FuncState *fs, expdesc *e) {
 225   if (e->k == VNONRELOC)
 226     freereg(fs, e->u.s.info);
 227 }
 228
 229
 230 static int addk (FuncState *fs, TValue *k, TValue *v) {
 231   lua_State *L = fs->L;
 232   TValue *idx = luaH_set(L, fs->h, k);
 233   Proto *f = fs->f;
 234   int oldsize = f->sizek;
 235   if (ttisnumber(idx)) {
 236     lua_assert(luaO_rawequalObj(&fs->f->k[cast_int(nvalue(idx))], v));
 237     return cast_int(nvalue(idx));
 238   }
 239   else {  /* constant not found; create a new entry */
 240     setnvalue(idx, cast_num(fs->nk));
 241     luaM_growvector(L, f->k, fs->nk, f->sizek, TValue,
 242                     MAXARG_Bx, "constant table overflow");
 243     while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
 244     setobj(L, &f->k[fs->nk], v);
 245     luaC_barrier(L, f, v);
 246     return fs->nk++;
 247   }
 248 }
 249
 250
 251 int luaK_stringK (FuncState *fs, TString *s) {
 252   TValue o;
 253   setsvalue(fs->L, &o, s);
 254   return addk(fs, &o, &o);
 255 }
 256
 257
 258 int luaK_numberK (FuncState *fs, lua_Number r) {
 259   TValue o;
 260   setnvalue(&o, r);
 261   return addk(fs, &o, &o);
 262 }
 263
 264
 265 static int boolK (FuncState *fs, int b) {
 266   TValue o;
 267   setbvalue(&o, b);
 268   return addk(fs, &o, &o);
 269 }
 270
 271
 272 static int nilK (FuncState *fs) {
 273   TValue k, v;
 274   setnilvalue(&v);
 275   /* cannot use nil as key; instead use table itself to represent nil */
 276   sethvalue(fs->L, &k, fs->h);
 277   return addk(fs, &k, &v);
 278 }
 279
 280
 281 void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
 282   if (e->k == VCALL) {  /* expression is an open function call? */
 283     SETARG_C(getcode(fs, e), nresults+1);
 284   }
 285   else if (e->k == VVARARG) {
 286     SETARG_B(getcode(fs, e), nresults+1);
 287     SETARG_A(getcode(fs, e), fs->freereg);
 288     luaK_reserveregs(fs, 1);
 289   }
 290 }
 291
 292
 293 void luaK_setoneret (FuncState *fs, expdesc *e) {
 294   if (e->k == VCALL) {  /* expression is an open function call? */
 295     e->k = VNONRELOC;
 296     e->u.s.info = GETARG_A(getcode(fs, e));
 297   }
 298   else if (e->k == VVARARG) {
 299     SETARG_B(getcode(fs, e), 2);
 300     e->k = VRELOCABLE;  /* can relocate its simple result */
 301   }
 302 }
 303
 304
 305 void luaK_dischargevars (FuncState *fs, expdesc *e) {
 306   switch (e->k) {
 307     case VLOCAL: {
 308       e->k = VNONRELOC;
 309       break;
 310     }
 311     case VUPVAL: {
 312       e->u.s.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.s.info, 0);
 313       e->k = VRELOCABLE;
 314       break;
 315     }
 316     case VGLOBAL: {
 317       e->u.s.info = luaK_codeABx(fs, OP_GETGLOBAL, 0, e->u.s.info);
 318       e->k = VRELOCABLE;
 319       break;
 320     }
 321     case VINDEXED: {
 322       freereg(fs, e->u.s.aux);
 323       freereg(fs, e->u.s.info);
 324       e->u.s.info = luaK_codeABC(fs, OP_GETTABLE, 0, e->u.s.info, e->u.s.aux);
 325       e->k = VRELOCABLE;
 326       break;
 327     }
 328     case VVARARG:
 329     case VCALL: {
 330       luaK_setoneret(fs, e);
 331       break;
 332     }
 333     default: break;  /* there is one value available (somewhere) */
 334   }
 335 }
 336
 337
 338 static int code_label (FuncState *fs, int A, int b, int jump) {
 339   luaK_getlabel(fs);  /* those instructions may be jump targets */
 340   return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
 341 }
 342
 343
 344 static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
 345   luaK_dischargevars(fs, e);
 346   switch (e->k) {
 347     case VNIL: {
 348       luaK_nil(fs, reg, 1);
 349       break;
 350     }
 351     case VFALSE:  case VTRUE: {
 352       luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
 353       break;
 354     }
 355     case VK: {
 356       luaK_codeABx(fs, OP_LOADK, reg, e->u.s.info);
 357       break;
 358     }
 359     case VKNUM: {
 360       luaK_codeABx(fs, OP_LOADK, reg, luaK_numberK(fs, e->u.nval));
 361       break;
 362     }
 363     case VRELOCABLE: {
 364       Instruction *pc = &getcode(fs, e);
 365       SETARG_A(*pc, reg);
 366       break;
 367     }
 368     case VNONRELOC: {
 369       if (reg != e->u.s.info)
 370         luaK_codeABC(fs, OP_MOVE, reg, e->u.s.info, 0);
 371       break;
 372     }
 373     default: {
 374       lua_assert(e->k == VVOID || e->k == VJMP);
 375       return;  /* nothing to do... */
 376     }
 377   }
 378   e->u.s.info = reg;
 379   e->k = VNONRELOC;
 380 }
 381
 382
 383 static void discharge2anyreg (FuncState *fs, expdesc *e) {
 384   if (e->k != VNONRELOC) {
 385     luaK_reserveregs(fs, 1);
 386     discharge2reg(fs, e, fs->freereg-1);
 387   }
 388 }
 389
 390
 391 static void exp2reg (FuncState *fs, expdesc *e, int reg) {
 392   discharge2reg(fs, e, reg);
 393   if (e->k == VJMP)
 394     luaK_concat(fs, &e->t, e->u.s.info);  /* put this jump in `t' list */
 395   if (hasjumps(e)) {
 396     int final;  /* position after whole expression */
 397     int p_f = NO_JUMP;  /* position of an eventual LOAD false */
 398     int p_t = NO_JUMP;  /* position of an eventual LOAD true */
 399     if (need_value(fs, e->t) || need_value(fs, e->f)) {
 400       int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
 401       p_f = code_label(fs, reg, 0, 1);
 402       p_t = code_label(fs, reg, 1, 0);
 403       luaK_patchtohere(fs, fj);
 404     }
 405     final = luaK_getlabel(fs);
 406     patchlistaux(fs, e->f, final, reg, p_f);
 407     patchlistaux(fs, e->t, final, reg, p_t);
 408   }
 409   e->f = e->t = NO_JUMP;
 410   e->u.s.info = reg;
 411   e->k = VNONRELOC;
 412 }
 413
 414
 415 void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
 416   luaK_dischargevars(fs, e);
 417   freeexp(fs, e);
 418   luaK_reserveregs(fs, 1);
 419   exp2reg(fs, e, fs->freereg - 1);
 420 }
 421
 422
 423 int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
 424   luaK_dischargevars(fs, e);
 425   if (e->k == VNONRELOC) {
 426     if (!hasjumps(e)) return e->u.s.info;  /* exp is already in a register */
 427     if (e->u.s.info >= fs->nactvar) {  /* reg. is not a local? */
 428       exp2reg(fs, e, e->u.s.info);  /* put value on it */
 429       return e->u.s.info;
 430     }
 431   }
 432   luaK_exp2nextreg(fs, e);  /* default */
 433   return e->u.s.info;
 434 }
 435
 436
 437 void luaK_exp2val (FuncState *fs, expdesc *e) {
 438   if (hasjumps(e))
 439     luaK_exp2anyreg(fs, e);
 440   else
 441     luaK_dischargevars(fs, e);
 442 }
 443
 444
 445 int luaK_exp2RK (FuncState *fs, expdesc *e) {
 446   luaK_exp2val(fs, e);
 447   switch (e->k) {
 448     case VKNUM:
 449     case VTRUE:
 450     case VFALSE:
 451     case VNIL: {
 452       if (fs->nk <= MAXINDEXRK) {  /* constant fit in RK operand? */
 453         e->u.s.info = (e->k == VNIL)  ? nilK(fs) :
 454                       (e->k == VKNUM) ? luaK_numberK(fs, e->u.nval) :
 455                                         boolK(fs, (e->k == VTRUE));
 456         e->k = VK;
 457         return RKASK(e->u.s.info);
 458       }
 459       else break;
 460     }
 461     case VK: {
 462       if (e->u.s.info <= MAXINDEXRK)  /* constant fit in argC? */
 463         return RKASK(e->u.s.info);
 464       else break;
 465     }
 466     default: break;
 467   }
 468   /* not a constant in the right range: put it in a register */
 469   return luaK_exp2anyreg(fs, e);
 470 }
 471
 472
 473 void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
 474   switch (var->k) {
 475     case VLOCAL: {
 476       freeexp(fs, ex);
 477       exp2reg(fs, ex, var->u.s.info);
 478       return;
 479     }
 480     case VUPVAL: {
 481       int e = luaK_exp2anyreg(fs, ex);
 482       luaK_codeABC(fs, OP_SETUPVAL, e, var->u.s.info, 0);
 483       break;
 484     }
 485     case VGLOBAL: {
 486       int e = luaK_exp2anyreg(fs, ex);
 487       luaK_codeABx(fs, OP_SETGLOBAL, e, var->u.s.info);
 488       break;
 489     }
 490     case VINDEXED: {
 491       int e = luaK_exp2RK(fs, ex);
 492       luaK_codeABC(fs, OP_SETTABLE, var->u.s.info, var->u.s.aux, e);
 493       break;
 494     }
 495     default: {
 496       lua_assert(0);  /* invalid var kind to store */
 497       break;
 498     }
 499   }
 500   freeexp(fs, ex);
 501 }
 502
 503
 504 void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
 505   int func;
 506   luaK_exp2anyreg(fs, e);
 507   freeexp(fs, e);
 508   func = fs->freereg;
 509   luaK_reserveregs(fs, 2);
 510   luaK_codeABC(fs, OP_SELF, func, e->u.s.info, luaK_exp2RK(fs, key));
 511   freeexp(fs, key);
 512   e->u.s.info = func;
 513   e->k = VNONRELOC;
 514 }
 515
 516
 517 static void invertjump (FuncState *fs, expdesc *e) {
 518   Instruction *pc = getjumpcontrol(fs, e->u.s.info);
 519   lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
 520                                            GET_OPCODE(*pc) != OP_TEST);
 521   SETARG_A(*pc, !(GETARG_A(*pc)));
 522 }
 523
 524
 525 static int jumponcond (FuncState *fs, expdesc *e, int cond) {
 526   if (e->k == VRELOCABLE) {
 527     Instruction ie = getcode(fs, e);
 528     if (GET_OPCODE(ie) == OP_NOT) {
 529       fs->pc--;  /* remove previous OP_NOT */
 530       return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
 531     }
 532     /* else go through */
 533   }
 534   discharge2anyreg(fs, e);
 535   freeexp(fs, e);
 536   return condjump(fs, OP_TESTSET, NO_REG, e->u.s.info, cond);
 537 }
 538
 539
 540 void luaK_goiftrue (FuncState *fs, expdesc *e) {
 541   int pc;  /* pc of last jump */
 542   luaK_dischargevars(fs, e);
 543   switch (e->k) {
 544     case VK: case VKNUM: case VTRUE: {
 545       pc = NO_JUMP;  /* always true; do nothing */
 546       break;
 547     }
 548     case VFALSE: {
 549       pc = luaK_jump(fs);  /* always jump */
 550       break;
 551     }
 552     case VJMP: {
 553       invertjump(fs, e);
 554       pc = e->u.s.info;
 555       break;
 556     }
 557     default: {
 558       pc = jumponcond(fs, e, 0);
 559       break;
 560     }
 561   }
 562   luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
 563   luaK_patchtohere(fs, e->t);
 564   e->t = NO_JUMP;
 565 }
 566
 567
 568 static void luaK_goiffalse (FuncState *fs, expdesc *e) {
 569   int pc;  /* pc of last jump */
 570   luaK_dischargevars(fs, e);
 571   switch (e->k) {
 572     case VNIL: case VFALSE: {
 573       pc = NO_JUMP;  /* always false; do nothing */
 574       break;
 575     }
 576     case VTRUE: {
 577       pc = luaK_jump(fs);  /* always jump */
 578       break;
 579     }
 580     case VJMP: {
 581       pc = e->u.s.info;
 582       break;
 583     }
 584     default: {
 585       pc = jumponcond(fs, e, 1);
 586       break;
 587     }
 588   }
 589   luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
 590   luaK_patchtohere(fs, e->f);
 591   e->f = NO_JUMP;
 592 }
 593
 594
 595 static void codenot (FuncState *fs, expdesc *e) {
 596   luaK_dischargevars(fs, e);
 597   switch (e->k) {
 598     case VNIL: case VFALSE: {
 599       e->k = VTRUE;
 600       break;
 601     }
 602     case VK: case VKNUM: case VTRUE: {
 603       e->k = VFALSE;
 604       break;
 605     }
 606     case VJMP: {
 607       invertjump(fs, e);
 608       break;
 609     }
 610     case VRELOCABLE:
 611     case VNONRELOC: {
 612       discharge2anyreg(fs, e);
 613       freeexp(fs, e);
 614       e->u.s.info = luaK_codeABC(fs, OP_NOT, 0, e->u.s.info, 0);
 615       e->k = VRELOCABLE;
 616       break;
 617     }
 618     default: {
 619       lua_assert(0);  /* cannot happen */
 620       break;
 621     }
 622   }
 623   /* interchange true and false lists */
 624   { int temp = e->f; e->f = e->t; e->t = temp; }
 625   removevalues(fs, e->f);
 626   removevalues(fs, e->t);
 627 }
 628
 629
 630 void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
 631   t->u.s.aux = luaK_exp2RK(fs, k);
 632   t->k = VINDEXED;
 633 }
 634
 635
 636 static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
 637   lua_Number v1, v2, r;
 638   if (!isnumeral(e1) || !isnumeral(e2)) return 0;
 639   v1 = e1->u.nval;
 640   v2 = e2->u.nval;
 641   switch (op) {
 642     case OP_ADD: r = luai_numadd(v1, v2); break;
 643     case OP_SUB: r = luai_numsub(v1, v2); break;
 644     case OP_MUL: r = luai_nummul(v1, v2); break;
 645     case OP_DIV:
 646       if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
 647       r = luai_numdiv(v1, v2); break;
 648     case OP_MOD:
 649       if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
 650       r = luai_nummod(v1, v2); break;
 651     case OP_POW: r = luai_numpow(v1, v2); break;
 652     case OP_UNM: r = luai_numunm(v1); break;
 653     case OP_LEN: return 0;  /* no constant folding for 'len' */
 654     default: lua_assert(0); r = 0; break;
 655   }
 656   if (luai_numisnan(r)) return 0;  /* do not attempt to produce NaN */
 657   e1->u.nval = r;
 658   return 1;
 659 }
 660
 661
 662 static void codearith (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2) {
 663   if (constfolding(op, e1, e2))
 664     return;
 665   else {
 666     int o2 = (op != OP_UNM && op != OP_LEN) ? luaK_exp2RK(fs, e2) : 0;
 667     int o1 = luaK_exp2RK(fs, e1);
 668     if (o1 > o2) {
 669       freeexp(fs, e1);
 670       freeexp(fs, e2);
 671     }
 672     else {
 673       freeexp(fs, e2);
 674       freeexp(fs, e1);
 675     }
 676     e1->u.s.info = luaK_codeABC(fs, op, 0, o1, o2);
 677     e1->k = VRELOCABLE;
 678   }
 679 }
 680
 681
 682 static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
 683                                                           expdesc *e2) {
 684   int o1 = luaK_exp2RK(fs, e1);
 685   int o2 = luaK_exp2RK(fs, e2);
 686   freeexp(fs, e2);
 687   freeexp(fs, e1);
 688   if (cond == 0 && op != OP_EQ) {
 689     int temp;  /* exchange args to replace by `<' or `<=' */
 690     temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
 691     cond = 1;
 692   }
 693   e1->u.s.info = condjump(fs, op, cond, o1, o2);
 694   e1->k = VJMP;
 695 }
 696
 697
 698 void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e) {
 699   expdesc e2;
 700   e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
 701   switch (op) {
 702     case OPR_MINUS: {
 703       if (!isnumeral(e))
 704         luaK_exp2anyreg(fs, e);  /* cannot operate on non-numeric constants */
 705       codearith(fs, OP_UNM, e, &e2);
 706       break;
 707     }
 708     case OPR_NOT: codenot(fs, e); break;
 709     case OPR_LEN: {
 710       luaK_exp2anyreg(fs, e);  /* cannot operate on constants */
 711       codearith(fs, OP_LEN, e, &e2);
 712       break;
 713     }
 714     default: lua_assert(0);
 715   }
 716 }
 717
 718
 719 void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
 720   switch (op) {
 721     case OPR_AND: {
 722       luaK_goiftrue(fs, v);
 723       break;
 724     }
 725     case OPR_OR: {
 726       luaK_goiffalse(fs, v);
 727       break;
 728     }
 729     case OPR_CONCAT: {
 730       luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
 731       break;
 732     }
 733     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
 734     case OPR_MOD: case OPR_POW: {
 735       if (!isnumeral(v)) luaK_exp2RK(fs, v);
 736       break;
 737     }
 738     default: {
 739       luaK_exp2RK(fs, v);
 740       break;
 741     }
 742   }
 743 }
 744
 745
 746 void luaK_posfix (FuncState *fs, BinOpr op, expdesc *e1, expdesc *e2) {
 747   switch (op) {
 748     case OPR_AND: {
 749       lua_assert(e1->t == NO_JUMP);  /* list must be closed */
 750       luaK_dischargevars(fs, e2);
 751       luaK_concat(fs, &e2->f, e1->f);
 752 #if 0
 753       *e1 = *e2;
 754 #else
 755       memcpy (e1, e2, sizeof (*e1));
 756 #endif
 757       break;
 758     }
 759     case OPR_OR: {
 760       lua_assert(e1->f == NO_JUMP);  /* list must be closed */
 761       luaK_dischargevars(fs, e2);
 762       luaK_concat(fs, &e2->t, e1->t);
 763 #if 0
 764       *e1 = *e2;
 765 #else
 766       memcpy (e1, e2, sizeof (*e1));
 767 #endif
 768       break;
 769     }
 770     case OPR_CONCAT: {
 771       luaK_exp2val(fs, e2);
 772       if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
 773         lua_assert(e1->u.s.info == GETARG_B(getcode(fs, e2))-1);
 774         freeexp(fs, e1);
 775         SETARG_B(getcode(fs, e2), e1->u.s.info);
 776         e1->k = VRELOCABLE; e1->u.s.info = e2->u.s.info;
 777       }
 778       else {
 779         luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
 780         codearith(fs, OP_CONCAT, e1, e2);
 781       }
 782       break;
 783     }
 784     case OPR_ADD: codearith(fs, OP_ADD, e1, e2); break;
 785     case OPR_SUB: codearith(fs, OP_SUB, e1, e2); break;
 786     case OPR_MUL: codearith(fs, OP_MUL, e1, e2); break;
 787     case OPR_DIV: codearith(fs, OP_DIV, e1, e2); break;
 788     case OPR_MOD: codearith(fs, OP_MOD, e1, e2); break;
 789     case OPR_POW: codearith(fs, OP_POW, e1, e2); break;
 790     case OPR_EQ: codecomp(fs, OP_EQ, 1, e1, e2); break;
 791     case OPR_NE: codecomp(fs, OP_EQ, 0, e1, e2); break;
 792     case OPR_LT: codecomp(fs, OP_LT, 1, e1, e2); break;
 793     case OPR_LE: codecomp(fs, OP_LE, 1, e1, e2); break;
 794     case OPR_GT: codecomp(fs, OP_LT, 0, e1, e2); break;
 795     case OPR_GE: codecomp(fs, OP_LE, 0, e1, e2); break;
 796     default: lua_assert(0);
 797   }
 798 }
 799
 800
 801 void luaK_fixline (FuncState *fs, int line) {
 802   fs->f->lineinfo[fs->pc - 1] = line;
 803 }
 804
 805
 806 static int luaK_code (FuncState *fs, Instruction i, int line) {
 807   Proto *f = fs->f;
 808   dischargejpc(fs);  /* `pc' will change */
 809   /* put new instruction in code array */
 810   luaM_growvector(fs->L, f->code, fs->pc, f->sizecode, Instruction,
 811                   MAX_INT, "code size overflow");
 812   f->code[fs->pc] = i;
 813   /* save corresponding line information */
 814   luaM_growvector(fs->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
 815                   MAX_INT, "code size overflow");
 816   f->lineinfo[fs->pc] = line;
 817   return fs->pc++;
 818 }
 819
 820
 821 int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
 822   lua_assert(getOpMode(o) == iABC);
 823   lua_assert(getBMode(o) != OpArgN || b == 0);
 824   lua_assert(getCMode(o) != OpArgN || c == 0);
 825   return luaK_code(fs, CREATE_ABC(o, a, b, c), fs->ls->lastline);
 826 }
 827
 828
 829 int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
 830   lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
 831   lua_assert(getCMode(o) == OpArgN);
 832   return luaK_code(fs, CREATE_ABx(o, a, bc), fs->ls->lastline);
 833 }
 834
 835
 836 void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
 837   int c;
 838   int b = (tostore == LUA_MULTRET) ? 0 : tostore;
 839   if (nelems == 0)
 840     c = 1;
 841   else
 842     c = ((unsigned) nelems + LFIELDS_PER_FLUSH - 1)/LFIELDS_PER_FLUSH;
 843   lua_assert(tostore != 0);
 844   if (c <= MAXARG_C)
 845     luaK_codeABC(fs, OP_SETLIST, base, b, c);
 846   else {
 847     luaK_codeABC(fs, OP_SETLIST, base, b, 0);
 848     luaK_code(fs, cast(Instruction, c), fs->ls->lastline);
 849   }
 850   fs->freereg = base + 1;  /* free registers with list values */
 851 }
 852