cvs.zerfleddert.de Git - proxmark3-svn/blob - liblua/lcode.c

   1 /*
   2 ** $Id: lcode.c,v 2.62 2012/08/16 17:34:28 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 "lstring.h"
  25 #include "ltable.h"
  26 #include "lvm.h"
  27
  28
  29 #define hasjumps(e)     ((e)->t != (e)->f)
  30
  31
  32 static int isnumeral(expdesc *e) {
  33   return (e->k == VKNUM && e->t == NO_JUMP && e->f == NO_JUMP);
  34 }
  35
  36
  37 void luaK_nil (FuncState *fs, int from, int n) {
  38   Instruction *previous;
  39   int l = from + n - 1;  /* last register to set nil */
  40   if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
  41     previous = &fs->f->code[fs->pc-1];
  42     if (GET_OPCODE(*previous) == OP_LOADNIL) {
  43       int pfrom = GETARG_A(*previous);
  44       int pl = pfrom + GETARG_B(*previous);
  45       if ((pfrom <= from && from <= pl + 1) ||
  46           (from <= pfrom && pfrom <= l + 1)) {  /* can connect both? */
  47         if (pfrom < from) from = pfrom;  /* from = min(from, pfrom) */
  48         if (pl > l) l = pl;  /* l = max(l, pl) */
  49         SETARG_A(*previous, from);
  50         SETARG_B(*previous, l - from);
  51         return;
  52       }
  53     }  /* else go through */
  54   }
  55   luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0);  /* else no optimization */
  56 }
  57
  58
  59 int luaK_jump (FuncState *fs) {
  60   int jpc = fs->jpc;  /* save list of jumps to here */
  61   int j;
  62   fs->jpc = NO_JUMP;
  63   j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
  64   luaK_concat(fs, &j, jpc);  /* keep them on hold */
  65   return j;
  66 }
  67
  68
  69 void luaK_ret (FuncState *fs, int first, int nret) {
  70   luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
  71 }
  72
  73
  74 static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
  75   luaK_codeABC(fs, op, A, B, C);
  76   return luaK_jump(fs);
  77 }
  78
  79
  80 static void fixjump (FuncState *fs, int pc, int dest) {
  81   Instruction *jmp = &fs->f->code[pc];
  82   int offset = dest-(pc+1);
  83   lua_assert(dest != NO_JUMP);
  84   if (abs(offset) > MAXARG_sBx)
  85     luaX_syntaxerror(fs->ls, "control structure too long");
  86   SETARG_sBx(*jmp, offset);
  87 }
  88
  89
  90 /*
  91 ** returns current `pc' and marks it as a jump target (to avoid wrong
  92 ** optimizations with consecutive instructions not in the same basic block).
  93 */
  94 int luaK_getlabel (FuncState *fs) {
  95   fs->lasttarget = fs->pc;
  96   return fs->pc;
  97 }
  98
  99
 100 static int getjump (FuncState *fs, int pc) {
 101   int offset = GETARG_sBx(fs->f->code[pc]);
 102   if (offset == NO_JUMP)  /* point to itself represents end of list */
 103     return NO_JUMP;  /* end of list */
 104   else
 105     return (pc+1)+offset;  /* turn offset into absolute position */
 106 }
 107
 108
 109 static Instruction *getjumpcontrol (FuncState *fs, int pc) {
 110   Instruction *pi = &fs->f->code[pc];
 111   if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
 112     return pi-1;
 113   else
 114     return pi;
 115 }
 116
 117
 118 /*
 119 ** check whether list has any jump that do not produce a value
 120 ** (or produce an inverted value)
 121 */
 122 static int need_value (FuncState *fs, int list) {
 123   for (; list != NO_JUMP; list = getjump(fs, list)) {
 124     Instruction i = *getjumpcontrol(fs, list);
 125     if (GET_OPCODE(i) != OP_TESTSET) return 1;
 126   }
 127   return 0;  /* not found */
 128 }
 129
 130
 131 static int patchtestreg (FuncState *fs, int node, int reg) {
 132   Instruction *i = getjumpcontrol(fs, node);
 133   if (GET_OPCODE(*i) != OP_TESTSET)
 134     return 0;  /* cannot patch other instructions */
 135   if (reg != NO_REG && reg != GETARG_B(*i))
 136     SETARG_A(*i, reg);
 137   else  /* no register to put value or register already has the value */
 138     *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
 139
 140   return 1;
 141 }
 142
 143
 144 static void removevalues (FuncState *fs, int list) {
 145   for (; list != NO_JUMP; list = getjump(fs, list))
 146       patchtestreg(fs, list, NO_REG);
 147 }
 148
 149
 150 static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
 151                           int dtarget) {
 152   while (list != NO_JUMP) {
 153     int next = getjump(fs, list);
 154     if (patchtestreg(fs, list, reg))
 155       fixjump(fs, list, vtarget);
 156     else
 157       fixjump(fs, list, dtarget);  /* jump to default target */
 158     list = next;
 159   }
 160 }
 161
 162
 163 static void dischargejpc (FuncState *fs) {
 164   patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
 165   fs->jpc = NO_JUMP;
 166 }
 167
 168
 169 void luaK_patchlist (FuncState *fs, int list, int target) {
 170   if (target == fs->pc)
 171     luaK_patchtohere(fs, list);
 172   else {
 173     lua_assert(target < fs->pc);
 174     patchlistaux(fs, list, target, NO_REG, target);
 175   }
 176 }
 177
 178
 179 LUAI_FUNC void luaK_patchclose (FuncState *fs, int list, int level) {
 180   level++;  /* argument is +1 to reserve 0 as non-op */
 181   while (list != NO_JUMP) {
 182     int next = getjump(fs, list);
 183     lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP &&
 184                 (GETARG_A(fs->f->code[list]) == 0 ||
 185                  GETARG_A(fs->f->code[list]) >= level));
 186     SETARG_A(fs->f->code[list], level);
 187     list = next;
 188   }
 189 }
 190
 191
 192 void luaK_patchtohere (FuncState *fs, int list) {
 193   luaK_getlabel(fs);
 194   luaK_concat(fs, &fs->jpc, list);
 195 }
 196
 197
 198 void luaK_concat (FuncState *fs, int *l1, int l2) {
 199   if (l2 == NO_JUMP) return;
 200   else if (*l1 == NO_JUMP)
 201     *l1 = l2;
 202   else {
 203     int list = *l1;
 204     int next;
 205     while ((next = getjump(fs, list)) != NO_JUMP)  /* find last element */
 206       list = next;
 207     fixjump(fs, list, l2);
 208   }
 209 }
 210
 211
 212 static int luaK_code (FuncState *fs, Instruction i) {
 213   Proto *f = fs->f;
 214   dischargejpc(fs);  /* `pc' will change */
 215   /* put new instruction in code array */
 216   luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,
 217                   MAX_INT, "opcodes");
 218   f->code[fs->pc] = i;
 219   /* save corresponding line information */
 220   luaM_growvector(fs->ls->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
 221                   MAX_INT, "opcodes");
 222   f->lineinfo[fs->pc] = fs->ls->lastline;
 223   return fs->pc++;
 224 }
 225
 226
 227 int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
 228   lua_assert(getOpMode(o) == iABC);
 229   lua_assert(getBMode(o) != OpArgN || b == 0);
 230   lua_assert(getCMode(o) != OpArgN || c == 0);
 231   lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);
 232   return luaK_code(fs, CREATE_ABC(o, a, b, c));
 233 }
 234
 235
 236 int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
 237   lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
 238   lua_assert(getCMode(o) == OpArgN);
 239   lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
 240   return luaK_code(fs, CREATE_ABx(o, a, bc));
 241 }
 242
 243
 244 static int codeextraarg (FuncState *fs, int a) {
 245   lua_assert(a <= MAXARG_Ax);
 246   return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a));
 247 }
 248
 249
 250 int luaK_codek (FuncState *fs, int reg, int k) {
 251   if (k <= MAXARG_Bx)
 252     return luaK_codeABx(fs, OP_LOADK, reg, k);
 253   else {
 254     int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);
 255     codeextraarg(fs, k);
 256     return p;
 257   }
 258 }
 259
 260
 261 void luaK_checkstack (FuncState *fs, int n) {
 262   int newstack = fs->freereg + n;
 263   if (newstack > fs->f->maxstacksize) {
 264     if (newstack >= MAXSTACK)
 265       luaX_syntaxerror(fs->ls, "function or expression too complex");
 266     fs->f->maxstacksize = cast_byte(newstack);
 267   }
 268 }
 269
 270
 271 void luaK_reserveregs (FuncState *fs, int n) {
 272   luaK_checkstack(fs, n);
 273   fs->freereg += n;
 274 }
 275
 276
 277 static void freereg (FuncState *fs, int reg) {
 278   if (!ISK(reg) && reg >= fs->nactvar) {
 279     fs->freereg--;
 280     lua_assert(reg == fs->freereg);
 281   }
 282 }
 283
 284
 285 static void freeexp (FuncState *fs, expdesc *e) {
 286   if (e->k == VNONRELOC)
 287     freereg(fs, e->u.info);
 288 }
 289
 290
 291 static int addk (FuncState *fs, TValue *key, TValue *v) {
 292   lua_State *L = fs->ls->L;
 293   TValue *idx = luaH_set(L, fs->h, key);
 294   Proto *f = fs->f;
 295   int k, oldsize;
 296   if (ttisnumber(idx)) {
 297     lua_Number n = nvalue(idx);
 298     lua_number2int(k, n);
 299     if (luaV_rawequalobj(&f->k[k], v))
 300       return k;
 301     /* else may be a collision (e.g., between 0.0 and "\0\0\0\0\0\0\0\0");
 302        go through and create a new entry for this value */
 303   }
 304   /* constant not found; create a new entry */
 305   oldsize = f->sizek;
 306   k = fs->nk;
 307   /* numerical value does not need GC barrier;
 308      table has no metatable, so it does not need to invalidate cache */
 309   setnvalue(idx, cast_num(k));
 310   luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");
 311   while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
 312   setobj(L, &f->k[k], v);
 313   fs->nk++;
 314   luaC_barrier(L, f, v);
 315   return k;
 316 }
 317
 318
 319 int luaK_stringK (FuncState *fs, TString *s) {
 320   TValue o;
 321   setsvalue(fs->ls->L, &o, s);
 322   return addk(fs, &o, &o);
 323 }
 324
 325
 326 int luaK_numberK (FuncState *fs, lua_Number r) {
 327   int n;
 328   lua_State *L = fs->ls->L;
 329   TValue o;
 330   setnvalue(&o, r);
 331   if (r == 0 || luai_numisnan(NULL, r)) {  /* handle -0 and NaN */
 332     /* use raw representation as key to avoid numeric problems */
 333     setsvalue(L, L->top++, luaS_newlstr(L, (char *)&r, sizeof(r)));
 334     n = addk(fs, L->top - 1, &o);
 335     L->top--;
 336   }
 337   else
 338     n = addk(fs, &o, &o);  /* regular case */
 339   return n;
 340 }
 341
 342
 343 static int boolK (FuncState *fs, int b) {
 344   TValue o;
 345   setbvalue(&o, b);
 346   return addk(fs, &o, &o);
 347 }
 348
 349
 350 static int nilK (FuncState *fs) {
 351   TValue k, v;
 352   setnilvalue(&v);
 353   /* cannot use nil as key; instead use table itself to represent nil */
 354   sethvalue(fs->ls->L, &k, fs->h);
 355   return addk(fs, &k, &v);
 356 }
 357
 358
 359 void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
 360   if (e->k == VCALL) {  /* expression is an open function call? */
 361     SETARG_C(getcode(fs, e), nresults+1);
 362   }
 363   else if (e->k == VVARARG) {
 364     SETARG_B(getcode(fs, e), nresults+1);
 365     SETARG_A(getcode(fs, e), fs->freereg);
 366     luaK_reserveregs(fs, 1);
 367   }
 368 }
 369
 370
 371 void luaK_setoneret (FuncState *fs, expdesc *e) {
 372   if (e->k == VCALL) {  /* expression is an open function call? */
 373     e->k = VNONRELOC;
 374     e->u.info = GETARG_A(getcode(fs, e));
 375   }
 376   else if (e->k == VVARARG) {
 377     SETARG_B(getcode(fs, e), 2);
 378     e->k = VRELOCABLE;  /* can relocate its simple result */
 379   }
 380 }
 381
 382
 383 void luaK_dischargevars (FuncState *fs, expdesc *e) {
 384   switch (e->k) {
 385     case VLOCAL: {
 386       e->k = VNONRELOC;
 387       break;
 388     }
 389     case VUPVAL: {
 390       e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
 391       e->k = VRELOCABLE;
 392       break;
 393     }
 394     case VINDEXED: {
 395       OpCode op = OP_GETTABUP;  /* assume 't' is in an upvalue */
 396       freereg(fs, e->u.ind.idx);
 397       if (e->u.ind.vt == VLOCAL) {  /* 't' is in a register? */
 398         freereg(fs, e->u.ind.t);
 399         op = OP_GETTABLE;
 400       }
 401       e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx);
 402       e->k = VRELOCABLE;
 403       break;
 404     }
 405     case VVARARG:
 406     case VCALL: {
 407       luaK_setoneret(fs, e);
 408       break;
 409     }
 410     default: break;  /* there is one value available (somewhere) */
 411   }
 412 }
 413
 414
 415 static int code_label (FuncState *fs, int A, int b, int jump) {
 416   luaK_getlabel(fs);  /* those instructions may be jump targets */
 417   return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
 418 }
 419
 420
 421 static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
 422   luaK_dischargevars(fs, e);
 423   switch (e->k) {
 424     case VNIL: {
 425       luaK_nil(fs, reg, 1);
 426       break;
 427     }
 428     case VFALSE: case VTRUE: {
 429       luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
 430       break;
 431     }
 432     case VK: {
 433       luaK_codek(fs, reg, e->u.info);
 434       break;
 435     }
 436     case VKNUM: {
 437       luaK_codek(fs, reg, luaK_numberK(fs, e->u.nval));
 438       break;
 439     }
 440     case VRELOCABLE: {
 441       Instruction *pc = &getcode(fs, e);
 442       SETARG_A(*pc, reg);
 443       break;
 444     }
 445     case VNONRELOC: {
 446       if (reg != e->u.info)
 447         luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
 448       break;
 449     }
 450     default: {
 451       lua_assert(e->k == VVOID || e->k == VJMP);
 452       return;  /* nothing to do... */
 453     }
 454   }
 455   e->u.info = reg;
 456   e->k = VNONRELOC;
 457 }
 458
 459
 460 static void discharge2anyreg (FuncState *fs, expdesc *e) {
 461   if (e->k != VNONRELOC) {
 462     luaK_reserveregs(fs, 1);
 463     discharge2reg(fs, e, fs->freereg-1);
 464   }
 465 }
 466
 467
 468 static void exp2reg (FuncState *fs, expdesc *e, int reg) {
 469   discharge2reg(fs, e, reg);
 470   if (e->k == VJMP)
 471     luaK_concat(fs, &e->t, e->u.info);  /* put this jump in `t' list */
 472   if (hasjumps(e)) {
 473     int final;  /* position after whole expression */
 474     int p_f = NO_JUMP;  /* position of an eventual LOAD false */
 475     int p_t = NO_JUMP;  /* position of an eventual LOAD true */
 476     if (need_value(fs, e->t) || need_value(fs, e->f)) {
 477       int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
 478       p_f = code_label(fs, reg, 0, 1);
 479       p_t = code_label(fs, reg, 1, 0);
 480       luaK_patchtohere(fs, fj);
 481     }
 482     final = luaK_getlabel(fs);
 483     patchlistaux(fs, e->f, final, reg, p_f);
 484     patchlistaux(fs, e->t, final, reg, p_t);
 485   }
 486   e->f = e->t = NO_JUMP;
 487   e->u.info = reg;
 488   e->k = VNONRELOC;
 489 }
 490
 491
 492 void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
 493   luaK_dischargevars(fs, e);
 494   freeexp(fs, e);
 495   luaK_reserveregs(fs, 1);
 496   exp2reg(fs, e, fs->freereg - 1);
 497 }
 498
 499
 500 int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
 501   luaK_dischargevars(fs, e);
 502   if (e->k == VNONRELOC) {
 503     if (!hasjumps(e)) return e->u.info;  /* exp is already in a register */
 504     if (e->u.info >= fs->nactvar) {  /* reg. is not a local? */
 505       exp2reg(fs, e, e->u.info);  /* put value on it */
 506       return e->u.info;
 507     }
 508   }
 509   luaK_exp2nextreg(fs, e);  /* default */
 510   return e->u.info;
 511 }
 512
 513
 514 void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
 515   if (e->k != VUPVAL || hasjumps(e))
 516     luaK_exp2anyreg(fs, e);
 517 }
 518
 519
 520 void luaK_exp2val (FuncState *fs, expdesc *e) {
 521   if (hasjumps(e))
 522     luaK_exp2anyreg(fs, e);
 523   else
 524     luaK_dischargevars(fs, e);
 525 }
 526
 527
 528 int luaK_exp2RK (FuncState *fs, expdesc *e) {
 529   luaK_exp2val(fs, e);
 530   switch (e->k) {
 531     case VTRUE:
 532     case VFALSE:
 533     case VNIL: {
 534       if (fs->nk <= MAXINDEXRK) {  /* constant fits in RK operand? */
 535         e->u.info = (e->k == VNIL) ? nilK(fs) : boolK(fs, (e->k == VTRUE));
 536         e->k = VK;
 537         return RKASK(e->u.info);
 538       }
 539       else break;
 540     }
 541     case VKNUM: {
 542       e->u.info = luaK_numberK(fs, e->u.nval);
 543       e->k = VK;
 544       /* go through */
 545     }
 546     case VK: {
 547       if (e->u.info <= MAXINDEXRK)  /* constant fits in argC? */
 548         return RKASK(e->u.info);
 549       else break;
 550     }
 551     default: break;
 552   }
 553   /* not a constant in the right range: put it in a register */
 554   return luaK_exp2anyreg(fs, e);
 555 }
 556
 557
 558 void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
 559   switch (var->k) {
 560     case VLOCAL: {
 561       freeexp(fs, ex);
 562       exp2reg(fs, ex, var->u.info);
 563       return;
 564     }
 565     case VUPVAL: {
 566       int e = luaK_exp2anyreg(fs, ex);
 567       luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
 568       break;
 569     }
 570     case VINDEXED: {
 571       OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;
 572       int e = luaK_exp2RK(fs, ex);
 573       luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e);
 574       break;
 575     }
 576     default: {
 577       lua_assert(0);  /* invalid var kind to store */
 578       break;
 579     }
 580   }
 581   freeexp(fs, ex);
 582 }
 583
 584
 585 void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
 586   int ereg;
 587   luaK_exp2anyreg(fs, e);
 588   ereg = e->u.info;  /* register where 'e' was placed */
 589   freeexp(fs, e);
 590   e->u.info = fs->freereg;  /* base register for op_self */
 591   e->k = VNONRELOC;
 592   luaK_reserveregs(fs, 2);  /* function and 'self' produced by op_self */
 593   luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));
 594   freeexp(fs, key);
 595 }
 596
 597
 598 static void invertjump (FuncState *fs, expdesc *e) {
 599   Instruction *pc = getjumpcontrol(fs, e->u.info);
 600   lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
 601                                            GET_OPCODE(*pc) != OP_TEST);
 602   SETARG_A(*pc, !(GETARG_A(*pc)));
 603 }
 604
 605
 606 static int jumponcond (FuncState *fs, expdesc *e, int cond) {
 607   if (e->k == VRELOCABLE) {
 608     Instruction ie = getcode(fs, e);
 609     if (GET_OPCODE(ie) == OP_NOT) {
 610       fs->pc--;  /* remove previous OP_NOT */
 611       return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
 612     }
 613     /* else go through */
 614   }
 615   discharge2anyreg(fs, e);
 616   freeexp(fs, e);
 617   return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond);
 618 }
 619
 620
 621 void luaK_goiftrue (FuncState *fs, expdesc *e) {
 622   int pc;  /* pc of last jump */
 623   luaK_dischargevars(fs, e);
 624   switch (e->k) {
 625     case VJMP: {
 626       invertjump(fs, e);
 627       pc = e->u.info;
 628       break;
 629     }
 630     case VK: case VKNUM: case VTRUE: {
 631       pc = NO_JUMP;  /* always true; do nothing */
 632       break;
 633     }
 634     default: {
 635       pc = jumponcond(fs, e, 0);
 636       break;
 637     }
 638   }
 639   luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
 640   luaK_patchtohere(fs, e->t);
 641   e->t = NO_JUMP;
 642 }
 643
 644
 645 void luaK_goiffalse (FuncState *fs, expdesc *e) {
 646   int pc;  /* pc of last jump */
 647   luaK_dischargevars(fs, e);
 648   switch (e->k) {
 649     case VJMP: {
 650       pc = e->u.info;
 651       break;
 652     }
 653     case VNIL: case VFALSE: {
 654       pc = NO_JUMP;  /* always false; do nothing */
 655       break;
 656     }
 657     default: {
 658       pc = jumponcond(fs, e, 1);
 659       break;
 660     }
 661   }
 662   luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
 663   luaK_patchtohere(fs, e->f);
 664   e->f = NO_JUMP;
 665 }
 666
 667
 668 static void codenot (FuncState *fs, expdesc *e) {
 669   luaK_dischargevars(fs, e);
 670   switch (e->k) {
 671     case VNIL: case VFALSE: {
 672       e->k = VTRUE;
 673       break;
 674     }
 675     case VK: case VKNUM: case VTRUE: {
 676       e->k = VFALSE;
 677       break;
 678     }
 679     case VJMP: {
 680       invertjump(fs, e);
 681       break;
 682     }
 683     case VRELOCABLE:
 684     case VNONRELOC: {
 685       discharge2anyreg(fs, e);
 686       freeexp(fs, e);
 687       e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0);
 688       e->k = VRELOCABLE;
 689       break;
 690     }
 691     default: {
 692       lua_assert(0);  /* cannot happen */
 693       break;
 694     }
 695   }
 696   /* interchange true and false lists */
 697   { int temp = e->f; e->f = e->t; e->t = temp; }
 698   removevalues(fs, e->f);
 699   removevalues(fs, e->t);
 700 }
 701
 702
 703 void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
 704   lua_assert(!hasjumps(t));
 705   t->u.ind.t = t->u.info;
 706   t->u.ind.idx = luaK_exp2RK(fs, k);
 707   t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL
 708                                  : check_exp(vkisinreg(t->k), VLOCAL);
 709   t->k = VINDEXED;
 710 }
 711
 712
 713 static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
 714   lua_Number r;
 715   if (!isnumeral(e1) || !isnumeral(e2)) return 0;
 716   if ((op == OP_DIV || op == OP_MOD) && e2->u.nval == 0)
 717     return 0;  /* do not attempt to divide by 0 */
 718   r = luaO_arith(op - OP_ADD + LUA_OPADD, e1->u.nval, e2->u.nval);
 719   e1->u.nval = r;
 720   return 1;
 721 }
 722
 723
 724 static void codearith (FuncState *fs, OpCode op,
 725                        expdesc *e1, expdesc *e2, int line) {
 726   if (constfolding(op, e1, e2))
 727     return;
 728   else {
 729     int o2 = (op != OP_UNM && op != OP_LEN) ? luaK_exp2RK(fs, e2) : 0;
 730     int o1 = luaK_exp2RK(fs, e1);
 731     if (o1 > o2) {
 732       freeexp(fs, e1);
 733       freeexp(fs, e2);
 734     }
 735     else {
 736       freeexp(fs, e2);
 737       freeexp(fs, e1);
 738     }
 739     e1->u.info = luaK_codeABC(fs, op, 0, o1, o2);
 740     e1->k = VRELOCABLE;
 741     luaK_fixline(fs, line);
 742   }
 743 }
 744
 745
 746 static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
 747                                                           expdesc *e2) {
 748   int o1 = luaK_exp2RK(fs, e1);
 749   int o2 = luaK_exp2RK(fs, e2);
 750   freeexp(fs, e2);
 751   freeexp(fs, e1);
 752   if (cond == 0 && op != OP_EQ) {
 753     int temp;  /* exchange args to replace by `<' or `<=' */
 754     temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
 755     cond = 1;
 756   }
 757   e1->u.info = condjump(fs, op, cond, o1, o2);
 758   e1->k = VJMP;
 759 }
 760
 761
 762 void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) {
 763   expdesc e2;
 764   e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
 765   switch (op) {
 766     case OPR_MINUS: {
 767       if (isnumeral(e))  /* minus constant? */
 768         e->u.nval = luai_numunm(NULL, e->u.nval);  /* fold it */
 769       else {
 770         luaK_exp2anyreg(fs, e);
 771         codearith(fs, OP_UNM, e, &e2, line);
 772       }
 773       break;
 774     }
 775     case OPR_NOT: codenot(fs, e); break;
 776     case OPR_LEN: {
 777       luaK_exp2anyreg(fs, e);  /* cannot operate on constants */
 778       codearith(fs, OP_LEN, e, &e2, line);
 779       break;
 780     }
 781     default: lua_assert(0);
 782   }
 783 }
 784
 785
 786 void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
 787   switch (op) {
 788     case OPR_AND: {
 789       luaK_goiftrue(fs, v);
 790       break;
 791     }
 792     case OPR_OR: {
 793       luaK_goiffalse(fs, v);
 794       break;
 795     }
 796     case OPR_CONCAT: {
 797       luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
 798       break;
 799     }
 800     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
 801     case OPR_MOD: case OPR_POW: {
 802       if (!isnumeral(v)) luaK_exp2RK(fs, v);
 803       break;
 804     }
 805     default: {
 806       luaK_exp2RK(fs, v);
 807       break;
 808     }
 809   }
 810 }
 811
 812
 813 void luaK_posfix (FuncState *fs, BinOpr op,
 814                   expdesc *e1, expdesc *e2, int line) {
 815   switch (op) {
 816     case OPR_AND: {
 817       lua_assert(e1->t == NO_JUMP);  /* list must be closed */
 818       luaK_dischargevars(fs, e2);
 819       luaK_concat(fs, &e2->f, e1->f);
 820       *e1 = *e2;
 821       break;
 822     }
 823     case OPR_OR: {
 824       lua_assert(e1->f == NO_JUMP);  /* list must be closed */
 825       luaK_dischargevars(fs, e2);
 826       luaK_concat(fs, &e2->t, e1->t);
 827       *e1 = *e2;
 828       break;
 829     }
 830     case OPR_CONCAT: {
 831       luaK_exp2val(fs, e2);
 832       if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
 833         lua_assert(e1->u.info == GETARG_B(getcode(fs, e2))-1);
 834         freeexp(fs, e1);
 835         SETARG_B(getcode(fs, e2), e1->u.info);
 836         e1->k = VRELOCABLE; e1->u.info = e2->u.info;
 837       }
 838       else {
 839         luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
 840         codearith(fs, OP_CONCAT, e1, e2, line);
 841       }
 842       break;
 843     }
 844     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
 845     case OPR_MOD: case OPR_POW: {
 846       codearith(fs, cast(OpCode, op - OPR_ADD + OP_ADD), e1, e2, line);
 847       break;
 848     }
 849     case OPR_EQ: case OPR_LT: case OPR_LE: {
 850       codecomp(fs, cast(OpCode, op - OPR_EQ + OP_EQ), 1, e1, e2);
 851       break;
 852     }
 853     case OPR_NE: case OPR_GT: case OPR_GE: {
 854       codecomp(fs, cast(OpCode, op - OPR_NE + OP_EQ), 0, e1, e2);
 855       break;
 856     }
 857     default: lua_assert(0);
 858   }
 859 }
 860
 861
 862 void luaK_fixline (FuncState *fs, int line) {
 863   fs->f->lineinfo[fs->pc - 1] = line;
 864 }
 865
 866
 867 void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
 868   int c =  (nelems - 1)/LFIELDS_PER_FLUSH + 1;
 869   int b = (tostore == LUA_MULTRET) ? 0 : tostore;
 870   lua_assert(tostore != 0);
 871   if (c <= MAXARG_C)
 872     luaK_codeABC(fs, OP_SETLIST, base, b, c);
 873   else if (c <= MAXARG_Ax) {
 874     luaK_codeABC(fs, OP_SETLIST, base, b, 0);
 875     codeextraarg(fs, c);
 876   }
 877   else
 878     luaX_syntaxerror(fs->ls, "constructor too long");
 879   fs->freereg = base + 1;  /* free registers with list values */
 880 }
 881