lvm.c

   1 /*
   2 ** $Id: lvm.c,v 2.63.1.3 2007/12/28 15:32:23 roberto Exp $
   3 ** Lua virtual machine
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #if 0
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #endif
  12
  13 #define lvm_c
  14 #define LUA_CORE
  15
  16 #include "lua.h"
  17
  18 #include "ldebug.h"
  19 #include "ldo.h"
  20 #include "lfunc.h"
  21 #include "lgc.h"
  22 #include "lobject.h"
  23 #include "lopcodes.h"
  24 #include "lstate.h"
  25 #include "lstring.h"
  26 #include "ltable.h"
  27 #include "ltm.h"
  28 #include "lvm.h"
  29
  30
  31
  32 /* limit for table tag-method chains (to avoid loops) */
  33 #define MAXTAGLOOP      100
  34
  35
  36 const TValue *luaV_tonumber (const TValue *obj, TValue *n) {
  37   lua_Number num;
  38   if (ttisnumber(obj)) return obj;
  39   if (ttisstring(obj) && luaO_str2d(svalue(obj), &num)) {
  40     setnvalue(n, num);
  41     return n;
  42   }
  43   else
  44     return NULL;
  45 }
  46
  47
  48 int luaV_tostring (lua_State *L, StkId obj) {
  49   if (!ttisnumber(obj))
  50     return 0;
  51   else {
  52     char s[LUAI_MAXNUMBER2STR];
  53     lua_Number n = nvalue(obj);
  54     lua_number2str(s, n);
  55     setsvalue2s(L, obj, luaS_new(L, s));
  56     return 1;
  57   }
  58 }
  59
  60
  61 static void traceexec (lua_State *L, const Instruction *pc) {
  62   lu_byte mask = L->hookmask;
  63   const Instruction *oldpc = L->savedpc;
  64   L->savedpc = pc;
  65   if ((mask & LUA_MASKCOUNT) && L->hookcount == 0) {
  66     resethookcount(L);
  67     luaD_callhook(L, LUA_HOOKCOUNT, -1);
  68   }
  69   if (mask & LUA_MASKLINE) {
  70     Proto *p = ci_func(L->ci)->l.p;
  71     int npc = pcRel(pc, p);
  72     int newline = getline(p, npc);
  73     /* call linehook when enter a new function, when jump back (loop),
  74        or when enter a new line */
  75     if (npc == 0 || pc <= oldpc || newline != getline(p, pcRel(oldpc, p)))
  76       luaD_callhook(L, LUA_HOOKLINE, newline);
  77   }
  78 }
  79
  80
  81 static void callTMres (lua_State *L, StkId res, const TValue *f,
  82                         const TValue *p1, const TValue *p2) {
  83   ptrdiff_t result = savestack(L, res);
  84   setobj2s(L, L->top, f);  /* push function */
  85   setobj2s(L, L->top+1, p1);  /* 1st argument */
  86   setobj2s(L, L->top+2, p2);  /* 2nd argument */
  87   luaD_checkstack(L, 3);
  88   L->top += 3;
  89   luaD_call(L, L->top - 3, 1);
  90   res = restorestack(L, result);
  91   L->top--;
  92   setobjs2s(L, res, L->top);
  93 }
  94
  95
  96
  97 static void callTM (lua_State *L, const TValue *f, const TValue *p1,
  98                     const TValue *p2, const TValue *p3) {
  99   setobj2s(L, L->top, f);  /* push function */
 100   setobj2s(L, L->top+1, p1);  /* 1st argument */
 101   setobj2s(L, L->top+2, p2);  /* 2nd argument */
 102   setobj2s(L, L->top+3, p3);  /* 3th argument */
 103   luaD_checkstack(L, 4);
 104   L->top += 4;
 105   luaD_call(L, L->top - 4, 0);
 106 }
 107
 108
 109 void luaV_gettable (lua_State *L, const TValue *t, TValue *key, StkId val) {
 110   int loop;
 111   for (loop = 0; loop < MAXTAGLOOP; loop++) {
 112     const TValue *tm;
 113     if (ttistable(t)) {  /* `t' is a table? */
 114       Table *h = hvalue(t);
 115       const TValue *res = luaH_get(h, key); /* do a primitive get */
 116       if (!ttisnil(res) ||  /* result is no nil? */
 117           (tm = fasttm(L, h->metatable, TM_INDEX)) == NULL) { /* or no TM? */
 118         setobj2s(L, val, res);
 119         return;
 120       }
 121       /* else will try the tag method */
 122     }
 123     else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_INDEX)))
 124       luaG_typeerror(L, t, "index");
 125     if (ttisfunction(tm)) {
 126       callTMres(L, val, tm, t, key);
 127       return;
 128     }
 129     t = tm;  /* else repeat with `tm' */
 130   }
 131   luaG_runerror(L, "loop in gettable");
 132 }
 133
 134
 135 void luaV_settable (lua_State *L, const TValue *t, TValue *key, StkId val) {
 136   int loop;
 137   for (loop = 0; loop < MAXTAGLOOP; loop++) {
 138     const TValue *tm;
 139     if (ttistable(t)) {  /* `t' is a table? */
 140       Table *h = hvalue(t);
 141       TValue *oldval = luaH_set(L, h, key); /* do a primitive set */
 142       if (!ttisnil(oldval) ||  /* result is no nil? */
 143           (tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL) { /* or no TM? */
 144         setobj2t(L, oldval, val);
 145         luaC_barriert(L, h, val);
 146         return;
 147       }
 148       /* else will try the tag method */
 149     }
 150     else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
 151       luaG_typeerror(L, t, "index");
 152     if (ttisfunction(tm)) {
 153       callTM(L, tm, t, key, val);
 154       return;
 155     }
 156     t = tm;  /* else repeat with `tm' */
 157   }
 158   luaG_runerror(L, "loop in settable");
 159 }
 160
 161
 162 static int call_binTM (lua_State *L, const TValue *p1, const TValue *p2,
 163                        StkId res, TMS event) {
 164   const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */
 165   if (ttisnil(tm))
 166     tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
 167   if (ttisnil(tm)) return 0;
 168   callTMres(L, res, tm, p1, p2);
 169   return 1;
 170 }
 171
 172
 173 static const TValue *get_compTM (lua_State *L, Table *mt1, Table *mt2,
 174                                   TMS event) {
 175   const TValue *tm1 = fasttm(L, mt1, event);
 176   const TValue *tm2;
 177   if (tm1 == NULL) return NULL;  /* no metamethod */
 178   if (mt1 == mt2) return tm1;  /* same metatables => same metamethods */
 179   tm2 = fasttm(L, mt2, event);
 180   if (tm2 == NULL) return NULL;  /* no metamethod */
 181   if (luaO_rawequalObj(tm1, tm2))  /* same metamethods? */
 182     return tm1;
 183   return NULL;
 184 }
 185
 186
 187 static int call_orderTM (lua_State *L, const TValue *p1, const TValue *p2,
 188                          TMS event) {
 189   const TValue *tm1 = luaT_gettmbyobj(L, p1, event);
 190   const TValue *tm2;
 191   if (ttisnil(tm1)) return -1;  /* no metamethod? */
 192   tm2 = luaT_gettmbyobj(L, p2, event);
 193   if (!luaO_rawequalObj(tm1, tm2))  /* different metamethods? */
 194     return -1;
 195   callTMres(L, L->top, tm1, p1, p2);
 196   return !l_isfalse(L->top);
 197 }
 198
 199
 200 static int l_strcmp (const TString *ls, const TString *rs) {
 201   const char *l = getstr(ls);
 202   size_t ll = ls->tsv.len;
 203   const char *r = getstr(rs);
 204   size_t lr = rs->tsv.len;
 205   for (;;) {
 206     int temp = strcoll(l, r);
 207     if (temp != 0) return temp;
 208     else {  /* strings are equal up to a `\0' */
 209       size_t len = strlen(l);  /* index of first `\0' in both strings */
 210       if (len == lr)  /* r is finished? */
 211         return (len == ll) ? 0 : 1;
 212       else if (len == ll)  /* l is finished? */
 213         return -1;  /* l is smaller than r (because r is not finished) */
 214       /* both strings longer than `len'; go on comparing (after the `\0') */
 215       len++;
 216       l += len; ll -= len; r += len; lr -= len;
 217     }
 218   }
 219 }
 220
 221
 222 int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
 223   int res;
 224   if (ttype(l) != ttype(r))
 225     return luaG_ordererror(L, l, r);
 226   else if (ttisnumber(l))
 227     return luai_numlt(nvalue(l), nvalue(r));
 228   else if (ttisstring(l))
 229     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) < 0;
 230   else if ((res = call_orderTM(L, l, r, TM_LT)) != -1)
 231     return res;
 232   return luaG_ordererror(L, l, r);
 233 }
 234
 235
 236 static int lessequal (lua_State *L, const TValue *l, const TValue *r) {
 237   int res;
 238   if (ttype(l) != ttype(r))
 239     return luaG_ordererror(L, l, r);
 240   else if (ttisnumber(l))
 241     return luai_numle(nvalue(l), nvalue(r));
 242   else if (ttisstring(l))
 243     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) <= 0;
 244   else if ((res = call_orderTM(L, l, r, TM_LE)) != -1)  /* first try `le' */
 245     return res;
 246   else if ((res = call_orderTM(L, r, l, TM_LT)) != -1)  /* else try `lt' */
 247     return !res;
 248   return luaG_ordererror(L, l, r);
 249 }
 250
 251
 252 int luaV_equalval (lua_State *L, const TValue *t1, const TValue *t2) {
 253   const TValue *tm;
 254   lua_assert(ttype(t1) == ttype(t2));
 255   switch (ttype(t1)) {
 256     case LUA_TNIL: return 1;
 257     case LUA_TNUMBER: return luai_numeq(nvalue(t1), nvalue(t2));
 258     case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */
 259     case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
 260     case LUA_TUSERDATA: {
 261       if (uvalue(t1) == uvalue(t2)) return 1;
 262       tm = get_compTM(L, uvalue(t1)->metatable, uvalue(t2)->metatable,
 263                          TM_EQ);
 264       break;  /* will try TM */
 265     }
 266     case LUA_TTABLE: {
 267       if (hvalue(t1) == hvalue(t2)) return 1;
 268       tm = get_compTM(L, hvalue(t1)->metatable, hvalue(t2)->metatable, TM_EQ);
 269       break;  /* will try TM */
 270     }
 271     default: return gcvalue(t1) == gcvalue(t2);
 272   }
 273   if (tm == NULL) return 0;  /* no TM? */
 274   callTMres(L, L->top, tm, t1, t2);  /* call TM */
 275   return !l_isfalse(L->top);
 276 }
 277
 278
 279 void luaV_concat (lua_State *L, int total, int last) {
 280   do {
 281     StkId top = L->base + last + 1;
 282     int n = 2;  /* number of elements handled in this pass (at least 2) */
 283     if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
 284       if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
 285         luaG_concaterror(L, top-2, top-1);
 286     } else if (tsvalue(top-1)->len == 0)  /* second op is empty? */
 287       (void)tostring(L, top - 2);  /* result is first op (as string) */
 288     else {
 289       /* at least two string values; get as many as possible */
 290       size_t tl = tsvalue(top-1)->len;
 291       char *buffer;
 292       int i;
 293       /* collect total length */
 294       for (n = 1; n < total && tostring(L, top-n-1); n++) {
 295         size_t l = tsvalue(top-n-1)->len;
 296         if (l >= MAX_SIZET - tl) luaG_runerror(L, "string length overflow");
 297         tl += l;
 298       }
 299       buffer = luaZ_openspace(L, &G(L)->buff, tl);
 300       tl = 0;
 301       for (i=n; i>0; i--) {  /* concat all strings */
 302         size_t l = tsvalue(top-i)->len;
 303         memcpy(buffer+tl, svalue(top-i), l);
 304         tl += l;
 305       }
 306       setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
 307     }
 308     total -= n-1;  /* got `n' strings to create 1 new */
 309     last -= n-1;
 310   } while (total > 1);  /* repeat until only 1 result left */
 311 }
 312
 313
 314 static void Arith (lua_State *L, StkId ra, const TValue *rb,
 315                    const TValue *rc, TMS op) {
 316   TValue tempb, tempc;
 317   const TValue *b, *c;
 318   if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
 319       (c = luaV_tonumber(rc, &tempc)) != NULL) {
 320     lua_Number nb = nvalue(b), nc = nvalue(c);
 321     switch (op) {
 322       case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;
 323       case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;
 324       case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;
 325       case TM_DIV: setnvalue(ra, luai_numdiv(nb, nc)); break;
 326       case TM_MOD: setnvalue(ra, luai_nummod(nb, nc)); break;
 327       case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;
 328       case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;
 329       default: lua_assert(0); break;
 330     }
 331   }
 332   else if (!call_binTM(L, rb, rc, ra, op))
 333     luaG_aritherror(L, rb, rc);
 334 }
 335
 336
 337
 338 /*
 339 ** some macros for common tasks in `luaV_execute'
 340 */
 341
 342 #define runtime_check(L, c)     { if (!(c)) break; }
 343
 344 #define RA(i)   (base+GETARG_A(i))
 345 /* to be used after possible stack reallocation */
 346 #define RB(i)   check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
 347 #define RC(i)   check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
 348 #define RKB(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
 349         ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
 350 #define RKC(i)  check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
 351         ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
 352 #define KBx(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, k+GETARG_Bx(i))
 353
 354
 355 #define dojump(L,pc,i)  {(pc) += (i); luai_threadyield(L);}
 356
 357
 358 #define Protect(x)      { L->savedpc = pc; {x;}; base = L->base; }
 359
 360
 361 #define arith_op(op,tm) { \
 362         TValue *rb = RKB(i); \
 363         TValue *rc = RKC(i); \
 364         if (ttisnumber(rb) && ttisnumber(rc)) { \
 365           lua_Number nb = nvalue(rb), nc = nvalue(rc); \
 366           setnvalue(ra, op(nb, nc)); \
 367         } \
 368         else \
 369           Protect(Arith(L, ra, rb, rc, tm)); \
 370       }
 371
 372
 373
 374 void luaV_execute (lua_State *L, int nexeccalls) {
 375   LClosure *cl;
 376   StkId base;
 377   TValue *k;
 378   const Instruction *pc;
 379  reentry:  /* entry point */
 380   lua_assert(isLua(L->ci));
 381   pc = L->savedpc;
 382   cl = &clvalue(L->ci->func)->l;
 383   base = L->base;
 384   k = cl->p->k;
 385   /* main loop of interpreter */
 386   for (;;) {
 387     const Instruction i = *pc++;
 388     StkId ra;
 389     if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&
 390         (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {
 391       traceexec(L, pc);
 392       if (L->status == LUA_YIELD) {  /* did hook yield? */
 393         L->savedpc = pc - 1;
 394         return;
 395       }
 396       base = L->base;
 397     }
 398     /* warning!! several calls may realloc the stack and invalidate `ra' */
 399     ra = RA(i);
 400     lua_assert(base == L->base && L->base == L->ci->base);
 401     lua_assert(base <= L->top && L->top <= L->stack + L->stacksize);
 402     lua_assert(L->top == L->ci->top || luaG_checkopenop(i));
 403     switch (GET_OPCODE(i)) {
 404       case OP_MOVE: {
 405         setobjs2s(L, ra, RB(i));
 406         continue;
 407       }
 408       case OP_LOADK: {
 409         setobj2s(L, ra, KBx(i));
 410         continue;
 411       }
 412       case OP_LOADBOOL: {
 413         setbvalue(ra, GETARG_B(i));
 414         if (GETARG_C(i)) pc++;  /* skip next instruction (if C) */
 415         continue;
 416       }
 417       case OP_LOADNIL: {
 418         TValue *rb = RB(i);
 419         do {
 420           setnilvalue(rb--);
 421         } while (rb >= ra);
 422         continue;
 423       }
 424       case OP_GETUPVAL: {
 425         int b = GETARG_B(i);
 426         setobj2s(L, ra, cl->upvals[b]->v);
 427         continue;
 428       }
 429       case OP_GETGLOBAL: {
 430         TValue g;
 431         TValue *rb = KBx(i);
 432         sethvalue(L, &g, cl->env);
 433         lua_assert(ttisstring(rb));
 434         Protect(luaV_gettable(L, &g, rb, ra));
 435         continue;
 436       }
 437       case OP_GETTABLE: {
 438         Protect(luaV_gettable(L, RB(i), RKC(i), ra));
 439         continue;
 440       }
 441       case OP_SETGLOBAL: {
 442         TValue g;
 443         sethvalue(L, &g, cl->env);
 444         lua_assert(ttisstring(KBx(i)));
 445         Protect(luaV_settable(L, &g, KBx(i), ra));
 446         continue;
 447       }
 448       case OP_SETUPVAL: {
 449         UpVal *uv = cl->upvals[GETARG_B(i)];
 450         setobj(L, uv->v, ra);
 451         luaC_barrier(L, uv, ra);
 452         continue;
 453       }
 454       case OP_SETTABLE: {
 455         Protect(luaV_settable(L, ra, RKB(i), RKC(i)));
 456         continue;
 457       }
 458       case OP_NEWTABLE: {
 459         int b = GETARG_B(i);
 460         int c = GETARG_C(i);
 461         sethvalue(L, ra, luaH_new(L, luaO_fb2int(b), luaO_fb2int(c)));
 462         Protect(luaC_checkGC(L));
 463         continue;
 464       }
 465       case OP_SELF: {
 466         StkId rb = RB(i);
 467         setobjs2s(L, ra+1, rb);
 468         Protect(luaV_gettable(L, rb, RKC(i), ra));
 469         continue;
 470       }
 471       case OP_ADD: {
 472         arith_op(luai_numadd, TM_ADD);
 473         continue;
 474       }
 475       case OP_SUB: {
 476         arith_op(luai_numsub, TM_SUB);
 477         continue;
 478       }
 479       case OP_MUL: {
 480         arith_op(luai_nummul, TM_MUL);
 481         continue;
 482       }
 483       case OP_DIV: {
 484         arith_op(luai_numdiv, TM_DIV);
 485         continue;
 486       }
 487       case OP_MOD: {
 488         arith_op(luai_nummod, TM_MOD);
 489         continue;
 490       }
 491       case OP_POW: {
 492         arith_op(luai_numpow, TM_POW);
 493         continue;
 494       }
 495       case OP_UNM: {
 496         TValue *rb = RB(i);
 497         if (ttisnumber(rb)) {
 498           lua_Number nb = nvalue(rb);
 499           setnvalue(ra, luai_numunm(nb));
 500         }
 501         else {
 502           Protect(Arith(L, ra, rb, rb, TM_UNM));
 503         }
 504         continue;
 505       }
 506       case OP_NOT: {
 507         int res = l_isfalse(RB(i));  /* next assignment may change this value */
 508         setbvalue(ra, res);
 509         continue;
 510       }
 511       case OP_LEN: {
 512         const TValue *rb = RB(i);
 513         switch (ttype(rb)) {
 514           case LUA_TTABLE: {
 515             setnvalue(ra, cast_num(luaH_getn(hvalue(rb))));
 516             break;
 517           }
 518           case LUA_TSTRING: {
 519             setnvalue(ra, cast_num(tsvalue(rb)->len));
 520             break;
 521           }
 522           default: {  /* try metamethod */
 523             Protect(
 524               if (!call_binTM(L, rb, luaO_nilobject, ra, TM_LEN))
 525                 luaG_typeerror(L, rb, "get length of");
 526             )
 527           }
 528         }
 529         continue;
 530       }
 531       case OP_CONCAT: {
 532         int b = GETARG_B(i);
 533         int c = GETARG_C(i);
 534         Protect(luaV_concat(L, c-b+1, c); luaC_checkGC(L));
 535         setobjs2s(L, RA(i), base+b);
 536         continue;
 537       }
 538       case OP_JMP: {
 539         dojump(L, pc, GETARG_sBx(i));
 540         continue;
 541       }
 542       case OP_EQ: {
 543         TValue *rb = RKB(i);
 544         TValue *rc = RKC(i);
 545         Protect(
 546           if (equalobj(L, rb, rc) == GETARG_A(i))
 547             dojump(L, pc, GETARG_sBx(*pc));
 548         )
 549         pc++;
 550         continue;
 551       }
 552       case OP_LT: {
 553         Protect(
 554           if (luaV_lessthan(L, RKB(i), RKC(i)) == GETARG_A(i))
 555             dojump(L, pc, GETARG_sBx(*pc));
 556         )
 557         pc++;
 558         continue;
 559       }
 560       case OP_LE: {
 561         Protect(
 562           if (lessequal(L, RKB(i), RKC(i)) == GETARG_A(i))
 563             dojump(L, pc, GETARG_sBx(*pc));
 564         )
 565         pc++;
 566         continue;
 567       }
 568       case OP_TEST: {
 569         if (l_isfalse(ra) != GETARG_C(i))
 570           dojump(L, pc, GETARG_sBx(*pc));
 571         pc++;
 572         continue;
 573       }
 574       case OP_TESTSET: {
 575         TValue *rb = RB(i);
 576         if (l_isfalse(rb) != GETARG_C(i)) {
 577           setobjs2s(L, ra, rb);
 578           dojump(L, pc, GETARG_sBx(*pc));
 579         }
 580         pc++;
 581         continue;
 582       }
 583       case OP_CALL: {
 584         int b = GETARG_B(i);
 585         int nresults = GETARG_C(i) - 1;
 586         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 587         L->savedpc = pc;
 588         switch (luaD_precall(L, ra, nresults)) {
 589           case PCRLUA: {
 590             nexeccalls++;
 591             goto reentry;  /* restart luaV_execute over new Lua function */
 592           }
 593           case PCRC: {
 594             /* it was a C function (`precall' called it); adjust results */
 595             if (nresults >= 0) L->top = L->ci->top;
 596             base = L->base;
 597             continue;
 598           }
 599           default: {
 600             return;  /* yield */
 601           }
 602         }
 603       }
 604       case OP_TAILCALL: {
 605         int b = GETARG_B(i);
 606         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 607         L->savedpc = pc;
 608         lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
 609         switch (luaD_precall(L, ra, LUA_MULTRET)) {
 610           case PCRLUA: {
 611             /* tail call: put new frame in place of previous one */
 612             CallInfo *ci = L->ci - 1;  /* previous frame */
 613             int aux;
 614             StkId func = ci->func;
 615             StkId pfunc = (ci+1)->func;  /* previous function index */
 616             if (L->openupval) luaF_close(L, ci->base);
 617             L->base = ci->base = ci->func + ((ci+1)->base - pfunc);
 618             for (aux = 0; pfunc+aux < L->top; aux++)  /* move frame down */
 619               setobjs2s(L, func+aux, pfunc+aux);
 620             ci->top = L->top = func+aux;  /* correct top */
 621             lua_assert(L->top == L->base + clvalue(func)->l.p->maxstacksize);
 622             ci->savedpc = L->savedpc;
 623             ci->tailcalls++;  /* one more call lost */
 624             L->ci--;  /* remove new frame */
 625             goto reentry;
 626           }
 627           case PCRC: {  /* it was a C function (`precall' called it) */
 628             base = L->base;
 629             continue;
 630           }
 631           default: {
 632             return;  /* yield */
 633           }
 634         }
 635       }
 636       case OP_RETURN: {
 637         int b = GETARG_B(i);
 638         if (b != 0) L->top = ra+b-1;
 639         if (L->openupval) luaF_close(L, base);
 640         L->savedpc = pc;
 641         b = luaD_poscall(L, ra);
 642         if (--nexeccalls == 0)  /* was previous function running `here'? */
 643           return;  /* no: return */
 644         else {  /* yes: continue its execution */
 645           if (b) L->top = L->ci->top;
 646           lua_assert(isLua(L->ci));
 647           lua_assert(GET_OPCODE(*((L->ci)->savedpc - 1)) == OP_CALL);
 648           goto reentry;
 649         }
 650       }
 651       case OP_FORLOOP: {
 652         lua_Number step = nvalue(ra+2);
 653         lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */
 654         lua_Number limit = nvalue(ra+1);
 655         if (luai_numlt(0, step) ? luai_numle(idx, limit)
 656                                 : luai_numle(limit, idx)) {
 657           dojump(L, pc, GETARG_sBx(i));  /* jump back */
 658           setnvalue(ra, idx);  /* update internal index... */
 659           setnvalue(ra+3, idx);  /* ...and external index */
 660         }
 661         continue;
 662       }
 663       case OP_FORPREP: {
 664         const TValue *init = ra;
 665         const TValue *plimit = ra+1;
 666         const TValue *pstep = ra+2;
 667         L->savedpc = pc;  /* next steps may throw errors */
 668         if (!tonumber(init, ra))
 669           luaG_runerror(L, LUA_QL("for") " initial value must be a number");
 670         else if (!tonumber(plimit, ra+1))
 671           luaG_runerror(L, LUA_QL("for") " limit must be a number");
 672         else if (!tonumber(pstep, ra+2))
 673           luaG_runerror(L, LUA_QL("for") " step must be a number");
 674         setnvalue(ra, luai_numsub(nvalue(ra), nvalue(pstep)));
 675         dojump(L, pc, GETARG_sBx(i));
 676         continue;
 677       }
 678       case OP_TFORLOOP: {
 679         StkId cb = ra + 3;  /* call base */
 680         setobjs2s(L, cb+2, ra+2);
 681         setobjs2s(L, cb+1, ra+1);
 682         setobjs2s(L, cb, ra);
 683         L->top = cb+3;  /* func. + 2 args (state and index) */
 684         Protect(luaD_call(L, cb, GETARG_C(i)));
 685         L->top = L->ci->top;
 686         cb = RA(i) + 3;  /* previous call may change the stack */
 687         if (!ttisnil(cb)) {  /* continue loop? */
 688           setobjs2s(L, cb-1, cb);  /* save control variable */
 689           dojump(L, pc, GETARG_sBx(*pc));  /* jump back */
 690         }
 691         pc++;
 692         continue;
 693       }
 694       case OP_SETLIST: {
 695         int n = GETARG_B(i);
 696         int c = GETARG_C(i);
 697         int last;
 698         Table *h;
 699         if (n == 0) {
 700           n = cast_int(L->top - ra) - 1;
 701           L->top = L->ci->top;
 702         }
 703         if (c == 0) c = cast_int(*pc++);
 704         runtime_check(L, ttistable(ra));
 705         h = hvalue(ra);
 706         last = ((c-1)*LFIELDS_PER_FLUSH) + n;
 707         if (last > h->sizearray)  /* needs more space? */
 708           luaH_resizearray(L, h, last);  /* pre-alloc it at once */
 709         for (; n > 0; n--) {
 710           TValue *val = ra+n;
 711           setobj2t(L, luaH_setnum(L, h, last--), val);
 712           luaC_barriert(L, h, val);
 713         }
 714         continue;
 715       }
 716       case OP_CLOSE: {
 717         luaF_close(L, ra);
 718         continue;
 719       }
 720       case OP_CLOSURE: {
 721         Proto *p;
 722         Closure *ncl;
 723         int nup, j;
 724         p = cl->p->p[GETARG_Bx(i)];
 725         nup = p->nups;
 726         ncl = luaF_newLclosure(L, nup, cl->env);
 727         ncl->l.p = p;
 728         for (j=0; j<nup; j++, pc++) {
 729           if (GET_OPCODE(*pc) == OP_GETUPVAL)
 730             ncl->l.upvals[j] = cl->upvals[GETARG_B(*pc)];
 731           else {
 732             lua_assert(GET_OPCODE(*pc) == OP_MOVE);
 733             ncl->l.upvals[j] = luaF_findupval(L, base + GETARG_B(*pc));
 734           }
 735         }
 736         setclvalue(L, ra, ncl);
 737         Protect(luaC_checkGC(L));
 738         continue;
 739       }
 740       case OP_VARARG: {
 741         int b = GETARG_B(i) - 1;
 742         int j;
 743         CallInfo *ci = L->ci;
 744         int n = cast_int(ci->base - ci->func) - cl->p->numparams - 1;
 745         if (b == LUA_MULTRET) {
 746           Protect(luaD_checkstack(L, n));
 747           ra = RA(i);  /* previous call may change the stack */
 748           b = n;
 749           L->top = ra + n;
 750         }
 751         for (j = 0; j < b; j++) {
 752           if (j < n) {
 753             setobjs2s(L, ra + j, ci->base - n + j);
 754           }
 755           else {
 756             setnilvalue(ra + j);
 757           }
 758         }
 759         continue;
 760       }
 761     }
 762   }
 763 }
 764