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