src/lvm.c

   1 /*
   2 ** $Id: lvm.c,v 2.63a 2006/06/05 15:58:59 roberto Exp $
   3 ** Lua virtual machine
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11
  12 #define lvm_c
  13 #define LUA_CORE
  14
  15 #include "lua.h"
  16
  17 #include "ldebug.h"
  18 #include "ldo.h"
  19 #include "lfunc.h"
  20 #include "lgc.h"
  21 #include "lobject.h"
  22 #include "lopcodes.h"
  23 #include "lstate.h"
  24 #include "lstring.h"
  25 #include "ltable.h"
  26 #include "ltm.h"
  27 #include "lvm.h"
  28
  29
  30
  31 /* limit for table tag-method chains (to avoid loops) */
  32 #define MAXTAGLOOP      100
  33
  34
  35 const TValue *luaV_tonumber (const TValue *obj, TValue *n) {
  36   lua_Number num;
  37   if (ttisnumber(obj)) return obj;
  38   if (ttisstring(obj) && luaO_str2d(svalue(obj), &num)) {
  39     setnvalue(n, num);
  40     return n;
  41   }
  42   else
  43     return NULL;
  44 }
  45
  46
  47 int luaV_tostring (lua_State *L, StkId obj) {
  48   if (!ttisnumber(obj))
  49     return 0;
  50   else {
  51     char s[LUAI_MAXNUMBER2STR];
  52     lua_Number n = nvalue(obj);
  53     lua_number2str(s, n);
  54     setsvalue2s(L, obj, luaS_new(L, s));
  55     return 1;
  56   }
  57 }
  58
  59
  60 static void traceexec (lua_State *L, const Instruction *pc) {
  61   lu_byte mask = L->hookmask;
  62   const Instruction *oldpc = L->savedpc;
  63   L->savedpc = pc;
  64   if (mask > LUA_MASKLINE) {  /* instruction-hook set? */
  65     if (L->hookcount == 0) {
  66       resethookcount(L);
  67       luaD_callhook(L, LUA_HOOKCOUNT, -1);
  68     }
  69   }
  70   if (mask & LUA_MASKLINE) {
  71     Proto *p = ci_func(L->ci)->l.p;
  72     int npc = pcRel(pc, p);
  73     int newline = getline(p, npc);
  74     /* call linehook when enter a new function, when jump back (loop),
  75        or when enter a new line */
  76     if (npc == 0 || pc <= oldpc || newline != getline(p, pcRel(oldpc, p)))
  77       luaD_callhook(L, LUA_HOOKLINE, newline);
  78   }
  79 }
  80
  81
  82 static void callTMres (lua_State *L, StkId res, const TValue *f,
  83                         const TValue *p1, const TValue *p2) {
  84   ptrdiff_t result = savestack(L, res);
  85   setobj2s(L, L->top, f);  /* push function */
  86   setobj2s(L, L->top+1, p1);  /* 1st argument */
  87   setobj2s(L, L->top+2, p2);  /* 2nd argument */
  88   luaD_checkstack(L, 3);
  89   L->top += 3;
  90   luaD_call(L, L->top - 3, 1);
  91   res = restorestack(L, result);
  92   L->top--;
  93   setobjs2s(L, res, L->top);
  94 }
  95
  96
  97
  98 static void callTM (lua_State *L, const TValue *f, const TValue *p1,
  99                     const TValue *p2, const TValue *p3) {
 100   setobj2s(L, L->top, f);  /* push function */
 101   setobj2s(L, L->top+1, p1);  /* 1st argument */
 102   setobj2s(L, L->top+2, p2);  /* 2nd argument */
 103   setobj2s(L, L->top+3, p3);  /* 3th argument */
 104   luaD_checkstack(L, 4);
 105   L->top += 4;
 106   luaD_call(L, L->top - 4, 0);
 107 }
 108
 109
 110 void luaV_gettable (lua_State *L, const TValue *t, TValue *key, StkId val) {
 111   int loop;
 112   for (loop = 0; loop < MAXTAGLOOP; loop++) {
 113     const TValue *tm;
 114     if (ttistable(t)) {  /* `t' is a table? */
 115       Table *h = hvalue(t);
 116       const TValue *res = luaH_get(h, key); /* do a primitive get */
 117       if (!ttisnil(res) ||  /* result is no nil? */
 118           (tm = fasttm(L, h->metatable, TM_INDEX)) == NULL) { /* or no TM? */
 119         setobj2s(L, val, res);
 120         return;
 121       }
 122       /* else will try the tag method */
 123     }
 124     else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_INDEX)))
 125       luaG_typeerror(L, t, "index");
 126     if (ttisfunction(tm)) {
 127       callTMres(L, val, tm, t, key);
 128       return;
 129     }
 130     t = tm;  /* else repeat with `tm' */
 131   }
 132   luaG_runerror(L, "loop in gettable");
 133 }
 134
 135
 136 void luaV_settable (lua_State *L, const TValue *t, TValue *key, StkId val) {
 137   int loop;
 138   for (loop = 0; loop < MAXTAGLOOP; loop++) {
 139     const TValue *tm;
 140     if (ttistable(t)) {  /* `t' is a table? */
 141       Table *h = hvalue(t);
 142       TValue *oldval = luaH_set(L, h, key); /* do a primitive set */
 143       if (!ttisnil(oldval) ||  /* result is no nil? */
 144           (tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL) { /* or no TM? */
 145         setobj2t(L, oldval, val);
 146         luaC_barriert(L, h, val);
 147         return;
 148       }
 149       /* else will try the tag method */
 150     }
 151     else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
 152       luaG_typeerror(L, t, "index");
 153     if (ttisfunction(tm)) {
 154       callTM(L, tm, t, key, val);
 155       return;
 156     }
 157     t = tm;  /* else repeat with `tm' */
 158   }
 159   luaG_runerror(L, "loop in settable");
 160 }
 161
 162
 163 static int call_binTM (lua_State *L, const TValue *p1, const TValue *p2,
 164                        StkId res, TMS event) {
 165   const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */
 166   if (ttisnil(tm))
 167     tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
 168   if (ttisnil(tm)) return 0;
 169   callTMres(L, res, tm, p1, p2);
 170   return 1;
 171 }
 172
 173
 174 static const TValue *get_compTM (lua_State *L, Table *mt1, Table *mt2,
 175                                   TMS event) {
 176   const TValue *tm1 = fasttm(L, mt1, event);
 177   const TValue *tm2;
 178   if (tm1 == NULL) return NULL;  /* no metamethod */
 179   if (mt1 == mt2) return tm1;  /* same metatables => same metamethods */
 180   tm2 = fasttm(L, mt2, event);
 181   if (tm2 == NULL) return NULL;  /* no metamethod */
 182   if (luaO_rawequalObj(tm1, tm2))  /* same metamethods? */
 183     return tm1;
 184   return NULL;
 185 }
 186
 187
 188 static int call_orderTM (lua_State *L, const TValue *p1, const TValue *p2,
 189                          TMS event) {
 190   const TValue *tm1 = luaT_gettmbyobj(L, p1, event);
 191   const TValue *tm2;
 192   if (ttisnil(tm1)) return -1;  /* no metamethod? */
 193   tm2 = luaT_gettmbyobj(L, p2, event);
 194   if (!luaO_rawequalObj(tm1, tm2))  /* different metamethods? */
 195     return -1;
 196   callTMres(L, L->top, tm1, p1, p2);
 197   return !l_isfalse(L->top);
 198 }
 199
 200
 201 static int l_strcmp (const TString *ls, const TString *rs) {
 202   const char *l = getstr(ls);
 203   size_t ll = ls->tsv.len;
 204   const char *r = getstr(rs);
 205   size_t lr = rs->tsv.len;
 206   for (;;) {
 207     int temp = strcoll(l, r);
 208     if (temp != 0) return temp;
 209     else {  /* strings are equal up to a `\0' */
 210       size_t len = strlen(l);  /* index of first `\0' in both strings */
 211       if (len == lr)  /* r is finished? */
 212         return (len == ll) ? 0 : 1;
 213       else if (len == ll)  /* l is finished? */
 214         return -1;  /* l is smaller than r (because r is not finished) */
 215       /* both strings longer than `len'; go on comparing (after the `\0') */
 216       len++;
 217       l += len; ll -= len; r += len; lr -= len;
 218     }
 219   }
 220 }
 221
 222
 223 int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
 224   int res;
 225   if (ttype(l) != ttype(r))
 226     return luaG_ordererror(L, l, r);
 227   else if (ttisnumber(l))
 228     return luai_numlt(nvalue(l), nvalue(r));
 229   else if (ttisstring(l))
 230     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) < 0;
 231   else if ((res = call_orderTM(L, l, r, TM_LT)) != -1)
 232     return res;
 233   return luaG_ordererror(L, l, r);
 234 }
 235
 236
 237 static int lessequal (lua_State *L, const TValue *l, const TValue *r) {
 238   int res;
 239   if (ttype(l) != ttype(r))
 240     return luaG_ordererror(L, l, r);
 241   else if (ttisnumber(l))
 242     return luai_numle(nvalue(l), nvalue(r));
 243   else if (ttisstring(l))
 244     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) <= 0;
 245   else if ((res = call_orderTM(L, l, r, TM_LE)) != -1)  /* first try `le' */
 246     return res;
 247   else if ((res = call_orderTM(L, r, l, TM_LT)) != -1)  /* else try `lt' */
 248     return !res;
 249   return luaG_ordererror(L, l, r);
 250 }
 251
 252
 253 int luaV_equalval (lua_State *L, const TValue *t1, const TValue *t2) {
 254   const TValue *tm;
 255   lua_assert(ttype(t1) == ttype(t2));
 256   switch (ttype(t1)) {
 257     case LUA_TNIL: return 1;
 258     case LUA_TNUMBER: return luai_numeq(nvalue(t1), nvalue(t2));
 259     case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */
 260     case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
 261     case LUA_TUSERDATA: {
 262       if (uvalue(t1) == uvalue(t2)) return 1;
 263       tm = get_compTM(L, uvalue(t1)->metatable, uvalue(t2)->metatable,
 264                          TM_EQ);
 265       break;  /* will try TM */
 266     }
 267     case LUA_TTABLE: {
 268       if (hvalue(t1) == hvalue(t2)) return 1;
 269       tm = get_compTM(L, hvalue(t1)->metatable, hvalue(t2)->metatable, TM_EQ);
 270       break;  /* will try TM */
 271     }
 272     default: return gcvalue(t1) == gcvalue(t2);
 273   }
 274   if (tm == NULL) return 0;  /* no TM? */
 275   callTMres(L, L->top, tm, t1, t2);  /* call TM */
 276   return !l_isfalse(L->top);
 277 }
 278
 279
 280 void luaV_concat (lua_State *L, int total, int last) {
 281   do {
 282     StkId top = L->base + last + 1;
 283     int n = 2;  /* number of elements handled in this pass (at least 2) */
 284     if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
 285       if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
 286         luaG_concaterror(L, top-2, top-1);
 287     } else if (tsvalue(top-1)->len == 0)  /* second op is empty? */
 288       (void)tostring(L, top - 2);  /* result is first op (as string) */
 289     else {
 290       /* at least two string values; get as many as possible */
 291       size_t tl = tsvalue(top-1)->len;
 292       char *buffer;
 293       int i;
 294       /* collect total length */
 295       for (n = 1; n < total && tostring(L, top-n-1); n++) {
 296         size_t l = tsvalue(top-n-1)->len;
 297         if (l >= MAX_SIZET - tl) luaG_runerror(L, "string length overflow");
 298         tl += l;
 299       }
 300       buffer = luaZ_openspace(L, &G(L)->buff, tl);
 301       tl = 0;
 302       for (i=n; i>0; i--) {  /* concat all strings */
 303         size_t l = tsvalue(top-i)->len;
 304         memcpy(buffer+tl, svalue(top-i), l);
 305         tl += l;
 306       }
 307       setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
 308     }
 309     total -= n-1;  /* got `n' strings to create 1 new */
 310     last -= n-1;
 311   } while (total > 1);  /* repeat until only 1 result left */
 312 }
 313
 314
 315 static void Arith (lua_State *L, StkId ra, const TValue *rb,
 316                    const TValue *rc, TMS op) {
 317   TValue tempb, tempc;
 318   const TValue *b, *c;
 319   if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
 320       (c = luaV_tonumber(rc, &tempc)) != NULL) {
 321     lua_Number nb = nvalue(b), nc = nvalue(c);
 322     switch (op) {
 323       case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;
 324       case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;
 325       case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;
 326       case TM_DIV: setnvalue(ra, luai_numdiv(nb, nc)); break;
 327       case TM_MOD: setnvalue(ra, luai_nummod(nb, nc)); break;
 328       case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;
 329       case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;
 330       default: lua_assert(0); break;
 331     }
 332   }
 333   else if (!call_binTM(L, rb, rc, ra, op))
 334     luaG_aritherror(L, rb, rc);
 335 }
 336
 337
 338
 339 /*
 340 ** some macros for common tasks in `luaV_execute'
 341 */
 342
 343 #define runtime_check(L, c)     { if (!(c)) break; }
 344
 345 #define RA(i)   (base+GETARG_A(i))
 346 /* to be used after possible stack reallocation */
 347 #define RB(i)   check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
 348 #define RC(i)   check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
 349 #define RKB(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
 350         ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
 351 #define RKC(i)  check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
 352         ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
 353 #define KBx(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, k+GETARG_Bx(i))
 354
 355
 356 #define dojump(L,pc,i)  {(pc) += (i); luai_threadyield(L);}
 357
 358
 359 #define Protect(x)      { L->savedpc = pc; {x;}; base = L->base; }
 360
 361
 362 #define arith_op(op,tm) { \
 363         TValue *rb = RKB(i); \
 364         TValue *rc = RKC(i); \
 365         if (ttisnumber(rb) && ttisnumber(rc)) { \
 366           lua_Number nb = nvalue(rb), nc = nvalue(rc); \
 367           setnvalue(ra, op(nb, nc)); \
 368         } \
 369         else \
 370           Protect(Arith(L, ra, rb, rc, tm)); \
 371       }
 372
 373
 374
 375 void luaV_execute (lua_State *L, int nexeccalls) {
 376   LClosure *cl;
 377   StkId base;
 378   TValue *k;
 379   const Instruction *pc;
 380  reentry:  /* entry point */
 381   lua_assert(isLua(L->ci));
 382   pc = L->savedpc;
 383   cl = &clvalue(L->ci->func)->l;
 384   base = L->base;
 385   k = cl->p->k;
 386   /* main loop of interpreter */
 387   for (;;) {
 388     const Instruction i = *pc++;
 389     StkId ra;
 390     if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&
 391         (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {
 392       traceexec(L, pc);
 393       if (L->status == LUA_YIELD) {  /* did hook yield? */
 394         L->savedpc = pc - 1;
 395         return;
 396       }
 397       base = L->base;
 398     }
 399     /* warning!! several calls may realloc the stack and invalidate `ra' */
 400     ra = RA(i);
 401     lua_assert(base == L->base && L->base == L->ci->base);
 402     lua_assert(base <= L->top && L->top <= L->stack + L->stacksize);
 403     lua_assert(L->top == L->ci->top || luaG_checkopenop(i));
 404     switch (GET_OPCODE(i)) {
 405       case OP_MOVE: {
 406         setobjs2s(L, ra, RB(i));
 407         continue;
 408       }
 409       case OP_LOADK: {
 410         setobj2s(L, ra, KBx(i));
 411         continue;
 412       }
 413       case OP_LOADBOOL: {
 414         setbvalue(ra, GETARG_B(i));
 415         if (GETARG_C(i)) pc++;  /* skip next instruction (if C) */
 416         continue;
 417       }
 418       case OP_LOADNIL: {
 419         TValue *rb = RB(i);
 420         do {
 421           setnilvalue(rb--);
 422         } while (rb >= ra);
 423         continue;
 424       }
 425       case OP_GETUPVAL: {
 426         int b = GETARG_B(i);
 427         setobj2s(L, ra, cl->upvals[b]->v);
 428         continue;
 429       }
 430       case OP_GETGLOBAL: {
 431         TValue g;
 432         TValue *rb = KBx(i);
 433         sethvalue(L, &g, cl->env);
 434         lua_assert(ttisstring(rb));
 435         Protect(luaV_gettable(L, &g, rb, ra));
 436         continue;
 437       }
 438       case OP_GETTABLE: {
 439         Protect(luaV_gettable(L, RB(i), RKC(i), ra));
 440         continue;
 441       }
 442       case OP_SETGLOBAL: {
 443         TValue g;
 444         sethvalue(L, &g, cl->env);
 445         lua_assert(ttisstring(KBx(i)));
 446         Protect(luaV_settable(L, &g, KBx(i), ra));
 447         continue;
 448       }
 449       case OP_SETUPVAL: {
 450         UpVal *uv = cl->upvals[GETARG_B(i)];
 451         setobj(L, uv->v, ra);
 452         luaC_barrier(L, uv, ra);
 453         continue;
 454       }
 455       case OP_SETTABLE: {
 456         Protect(luaV_settable(L, ra, RKB(i), RKC(i)));
 457         continue;
 458       }
 459       case OP_NEWTABLE: {
 460         int b = GETARG_B(i);
 461         int c = GETARG_C(i);
 462         sethvalue(L, ra, luaH_new(L, luaO_fb2int(b), luaO_fb2int(c)));
 463         Protect(luaC_checkGC(L));
 464         continue;
 465       }
 466       case OP_SELF: {
 467         StkId rb = RB(i);
 468         setobjs2s(L, ra+1, rb);
 469         Protect(luaV_gettable(L, rb, RKC(i), ra));
 470         continue;
 471       }
 472       case OP_ADD: {
 473         arith_op(luai_numadd, TM_ADD);
 474         continue;
 475       }
 476       case OP_SUB: {
 477         arith_op(luai_numsub, TM_SUB);
 478         continue;
 479       }
 480       case OP_MUL: {
 481         arith_op(luai_nummul, TM_MUL);
 482         continue;
 483       }
 484       case OP_DIV: {
 485         arith_op(luai_numdiv, TM_DIV);
 486         continue;
 487       }
 488       case OP_MOD: {
 489         arith_op(luai_nummod, TM_MOD);
 490         continue;
 491       }
 492       case OP_POW: {
 493         arith_op(luai_numpow, TM_POW);
 494         continue;
 495       }
 496       case OP_UNM: {
 497         TValue *rb = RB(i);
 498         if (ttisnumber(rb)) {
 499           lua_Number nb = nvalue(rb);
 500           setnvalue(ra, luai_numunm(nb));
 501         }
 502         else {
 503           Protect(Arith(L, ra, rb, rb, TM_UNM));
 504         }
 505         continue;
 506       }
 507       case OP_NOT: {
 508         int res = l_isfalse(RB(i));  /* next assignment may change this value */
 509         setbvalue(ra, res);
 510         continue;
 511       }
 512       case OP_LEN: {
 513         const TValue *rb = RB(i);
 514         switch (ttype(rb)) {
 515           case LUA_TTABLE: {
 516             setnvalue(ra, cast_num(luaH_getn(hvalue(rb))));
 517             break;
 518           }
 519           case LUA_TSTRING: {
 520             setnvalue(ra, cast_num(tsvalue(rb)->len));
 521             break;
 522           }
 523           default: {  /* try metamethod */
 524             Protect(
 525               if (!call_binTM(L, rb, luaO_nilobject, ra, TM_LEN))
 526                 luaG_typeerror(L, rb, "get length of");
 527             )
 528           }
 529         }
 530         continue;
 531       }
 532       case OP_CONCAT: {
 533         int b = GETARG_B(i);
 534         int c = GETARG_C(i);
 535         Protect(luaV_concat(L, c-b+1, c); luaC_checkGC(L));
 536         setobjs2s(L, RA(i), base+b);
 537         continue;
 538       }
 539       case OP_JMP: {
 540         dojump(L, pc, GETARG_sBx(i));
 541         continue;
 542       }
 543       case OP_EQ: {
 544         TValue *rb = RKB(i);
 545         TValue *rc = RKC(i);
 546         Protect(
 547           if (equalobj(L, rb, rc) == GETARG_A(i))
 548             dojump(L, pc, GETARG_sBx(*pc));
 549         )
 550         pc++;
 551         continue;
 552       }
 553       case OP_LT: {
 554         Protect(
 555           if (luaV_lessthan(L, RKB(i), RKC(i)) == GETARG_A(i))
 556             dojump(L, pc, GETARG_sBx(*pc));
 557         )
 558         pc++;
 559         continue;
 560       }
 561       case OP_LE: {
 562         Protect(
 563           if (lessequal(L, RKB(i), RKC(i)) == GETARG_A(i))
 564             dojump(L, pc, GETARG_sBx(*pc));
 565         )
 566         pc++;
 567         continue;
 568       }
 569       case OP_TEST: {
 570         if (l_isfalse(ra) != GETARG_C(i))
 571           dojump(L, pc, GETARG_sBx(*pc));
 572         pc++;
 573         continue;
 574       }
 575       case OP_TESTSET: {
 576         TValue *rb = RB(i);
 577         if (l_isfalse(rb) != GETARG_C(i)) {
 578           setobjs2s(L, ra, rb);
 579           dojump(L, pc, GETARG_sBx(*pc));
 580         }
 581         pc++;
 582         continue;
 583       }
 584       case OP_CALL: {
 585         int b = GETARG_B(i);
 586         int nresults = GETARG_C(i) - 1;
 587         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 588         L->savedpc = pc;
 589         switch (luaD_precall(L, ra, nresults)) {
 590           case PCRLUA: {
 591             nexeccalls++;
 592             goto reentry;  /* restart luaV_execute over new Lua function */
 593           }
 594           case PCRC: {
 595             /* it was a C function (`precall' called it); adjust results */
 596             if (nresults >= 0) L->top = L->ci->top;
 597             base = L->base;
 598             continue;
 599           }
 600           default: {
 601             return;  /* yield */
 602           }
 603         }
 604       }
 605       case OP_TAILCALL: {
 606         int b = GETARG_B(i);
 607         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 608         L->savedpc = pc;
 609         lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
 610         switch (luaD_precall(L, ra, LUA_MULTRET)) {
 611           case PCRLUA: {
 612             /* tail call: put new frame in place of previous one */
 613             CallInfo *ci = L->ci - 1;  /* previous frame */
 614             int aux;
 615             StkId func = ci->func;
 616             StkId pfunc = (ci+1)->func;  /* previous function index */
 617             if (L->openupval) luaF_close(L, ci->base);
 618             L->base = ci->base = ci->func + ((ci+1)->base - pfunc);
 619             for (aux = 0; pfunc+aux < L->top; aux++)  /* move frame down */
 620               setobjs2s(L, func+aux, pfunc+aux);
 621             ci->top = L->top = func+aux;  /* correct top */
 622             lua_assert(L->top == L->base + clvalue(func)->l.p->maxstacksize);
 623             ci->savedpc = L->savedpc;
 624             ci->tailcalls++;  /* one more call lost */
 625             L->ci--;  /* remove new frame */
 626             goto reentry;
 627           }
 628           case PCRC: {  /* it was a C function (`precall' called it) */
 629             base = L->base;
 630             continue;
 631           }
 632           default: {
 633             return;  /* yield */
 634           }
 635         }
 636       }
 637       case OP_RETURN: {
 638         int b = GETARG_B(i);
 639         if (b != 0) L->top = ra+b-1;
 640         if (L->openupval) luaF_close(L, base);
 641         L->savedpc = pc;
 642         b = luaD_poscall(L, ra);
 643         if (--nexeccalls == 0)  /* was previous function running `here'? */
 644           return;  /* no: return */
 645         else {  /* yes: continue its execution */
 646           if (b) L->top = L->ci->top;
 647           lua_assert(isLua(L->ci));
 648           lua_assert(GET_OPCODE(*((L->ci)->savedpc - 1)) == OP_CALL);
 649           goto reentry;
 650         }
 651       }
 652       case OP_FORLOOP: {
 653         lua_Number step = nvalue(ra+2);
 654         lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */
 655         lua_Number limit = nvalue(ra+1);
 656         if (luai_numlt(0, step) ? luai_numle(idx, limit)
 657                                 : luai_numle(limit, idx)) {
 658           dojump(L, pc, GETARG_sBx(i));  /* jump back */
 659           setnvalue(ra, idx);  /* update internal index... */
 660           setnvalue(ra+3, idx);  /* ...and external index */
 661         }
 662         continue;
 663       }
 664       case OP_FORPREP: {
 665         const TValue *init = ra;
 666         const TValue *plimit = ra+1;
 667         const TValue *pstep = ra+2;
 668         L->savedpc = pc;  /* next steps may throw errors */
 669         if (!tonumber(init, ra))
 670           luaG_runerror(L, LUA_QL("for") " initial value must be a number");
 671         else if (!tonumber(plimit, ra+1))
 672           luaG_runerror(L, LUA_QL("for") " limit must be a number");
 673         else if (!tonumber(pstep, ra+2))
 674           luaG_runerror(L, LUA_QL("for") " step must be a number");
 675         setnvalue(ra, luai_numsub(nvalue(ra), nvalue(pstep)));
 676         dojump(L, pc, GETARG_sBx(i));
 677         continue;
 678       }
 679       case OP_TFORLOOP: {
 680         StkId cb = ra + 3;  /* call base */
 681         setobjs2s(L, cb+2, ra+2);
 682         setobjs2s(L, cb+1, ra+1);
 683         setobjs2s(L, cb, ra);
 684         L->top = cb+3;  /* func. + 2 args (state and index) */
 685         Protect(luaD_call(L, cb, GETARG_C(i)));
 686         L->top = L->ci->top;
 687         cb = RA(i) + 3;  /* previous call may change the stack */
 688         if (!ttisnil(cb)) {  /* continue loop? */
 689           setobjs2s(L, cb-1, cb);  /* save control variable */
 690           dojump(L, pc, GETARG_sBx(*pc));  /* jump back */
 691         }
 692         pc++;
 693         continue;
 694       }
 695       case OP_SETLIST: {
 696         int n = GETARG_B(i);
 697         int c = GETARG_C(i);
 698         int last;
 699         Table *h;
 700         if (n == 0) {
 701           n = cast_int(L->top - ra) - 1;
 702           L->top = L->ci->top;
 703         }
 704         if (c == 0) c = cast_int(*pc++);
 705         runtime_check(L, ttistable(ra));
 706         h = hvalue(ra);
 707         last = ((c-1)*LFIELDS_PER_FLUSH) + n;
 708         if (last > h->sizearray)  /* needs more space? */
 709           luaH_resizearray(L, h, last);  /* pre-alloc it at once */
 710         for (; n > 0; n--) {
 711           TValue *val = ra+n;
 712           setobj2t(L, luaH_setnum(L, h, last--), val);
 713           luaC_barriert(L, h, val);
 714         }
 715         continue;
 716       }
 717       case OP_CLOSE: {
 718         luaF_close(L, ra);
 719         continue;
 720       }
 721       case OP_CLOSURE: {
 722         Proto *p;
 723         Closure *ncl;
 724         int nup, j;
 725         p = cl->p->p[GETARG_Bx(i)];
 726         nup = p->nups;
 727         ncl = luaF_newLclosure(L, nup, cl->env);
 728         ncl->l.p = p;
 729         for (j=0; j<nup; j++, pc++) {
 730           if (GET_OPCODE(*pc) == OP_GETUPVAL)
 731             ncl->l.upvals[j] = cl->upvals[GETARG_B(*pc)];
 732           else {
 733             lua_assert(GET_OPCODE(*pc) == OP_MOVE);
 734             ncl->l.upvals[j] = luaF_findupval(L, base + GETARG_B(*pc));
 735           }
 736         }
 737         setclvalue(L, ra, ncl);
 738         Protect(luaC_checkGC(L));
 739         continue;
 740       }
 741       case OP_VARARG: {
 742         int b = GETARG_B(i) - 1;
 743         int j;
 744         CallInfo *ci = L->ci;
 745         int n = cast_int(ci->base - ci->func) - cl->p->numparams - 1;
 746         if (b == LUA_MULTRET) {
 747           Protect(luaD_checkstack(L, n));
 748           ra = RA(i);  /* previous call may change the stack */
 749           b = n;
 750           L->top = ra + n;
 751         }
 752         for (j = 0; j < b; j++) {
 753           if (j < n) {
 754             setobjs2s(L, ra + j, ci->base - n + j);
 755           }
 756           else {
 757             setnilvalue(ra + j);
 758           }
 759         }
 760         continue;
 761       }
 762     }
 763   }
 764 }
 765