src/func.xyz/l51/src/lvm.c

   1 /*
   2 ** $Id: lvm.c,v 2.63.1.5 2011/08/17 20:43:11 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   TValue temp;
 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         h->flags = 0;
 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     /* else repeat with `tm' */
 158     setobj(L, &temp, tm);  /* avoid pointing inside table (may rehash) */
 159     t = &temp;
 160   }
 161   luaG_runerror(L, "loop in settable");
 162 }
 163
 164
 165 static int call_binTM (lua_State *L, const TValue *p1, const TValue *p2,
 166                        StkId res, TMS event) {
 167   const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */
 168   if (ttisnil(tm))
 169     tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
 170   if (ttisnil(tm)) return 0;
 171   callTMres(L, res, tm, p1, p2);
 172   return 1;
 173 }
 174
 175
 176 static const TValue *get_compTM (lua_State *L, Table *mt1, Table *mt2,
 177                                   TMS event) {
 178   const TValue *tm1 = fasttm(L, mt1, event);
 179   const TValue *tm2;
 180   if (tm1 == NULL) return NULL;  /* no metamethod */
 181   if (mt1 == mt2) return tm1;  /* same metatables => same metamethods */
 182   tm2 = fasttm(L, mt2, event);
 183   if (tm2 == NULL) return NULL;  /* no metamethod */
 184   if (luaO_rawequalObj(tm1, tm2))  /* same metamethods? */
 185     return tm1;
 186   return NULL;
 187 }
 188
 189
 190 static int call_orderTM (lua_State *L, const TValue *p1, const TValue *p2,
 191                          TMS event) {
 192   const TValue *tm1 = luaT_gettmbyobj(L, p1, event);
 193   const TValue *tm2;
 194   if (ttisnil(tm1)) return -1;  /* no metamethod? */
 195   tm2 = luaT_gettmbyobj(L, p2, event);
 196   if (!luaO_rawequalObj(tm1, tm2))  /* different metamethods? */
 197     return -1;
 198   callTMres(L, L->top, tm1, p1, p2);
 199   return !l_isfalse(L->top);
 200 }
 201
 202
 203 static int l_strcmp (const TString *ls, const TString *rs) {
 204   const char *l = getstr(ls);
 205   size_t ll = ls->tsv.len;
 206   const char *r = getstr(rs);
 207   size_t lr = rs->tsv.len;
 208   for (;;) {
 209     int temp = strcoll(l, r);
 210     if (temp != 0) return temp;
 211     else {  /* strings are equal up to a `\0' */
 212       size_t len = strlen(l);  /* index of first `\0' in both strings */
 213       if (len == lr)  /* r is finished? */
 214         return (len == ll) ? 0 : 1;
 215       else if (len == ll)  /* l is finished? */
 216         return -1;  /* l is smaller than r (because r is not finished) */
 217       /* both strings longer than `len'; go on comparing (after the `\0') */
 218       len++;
 219       l += len; ll -= len; r += len; lr -= len;
 220     }
 221   }
 222 }
 223
 224
 225 int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
 226   int res;
 227   if (ttype(l) != ttype(r))
 228     return luaG_ordererror(L, l, r);
 229   else if (ttisnumber(l))
 230     return luai_numlt(nvalue(l), nvalue(r));
 231   else if (ttisstring(l))
 232     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) < 0;
 233   else if ((res = call_orderTM(L, l, r, TM_LT)) != -1)
 234     return res;
 235   return luaG_ordererror(L, l, r);
 236 }
 237
 238
 239 static int lessequal (lua_State *L, const TValue *l, const TValue *r) {
 240   int res;
 241   if (ttype(l) != ttype(r))
 242     return luaG_ordererror(L, l, r);
 243   else if (ttisnumber(l))
 244     return luai_numle(nvalue(l), nvalue(r));
 245   else if (ttisstring(l))
 246     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) <= 0;
 247   else if ((res = call_orderTM(L, l, r, TM_LE)) != -1)  /* first try `le' */
 248     return res;
 249   else if ((res = call_orderTM(L, r, l, TM_LT)) != -1)  /* else try `lt' */
 250     return !res;
 251   return luaG_ordererror(L, l, r);
 252 }
 253
 254
 255 int luaV_equalval (lua_State *L, const TValue *t1, const TValue *t2) {
 256   const TValue *tm;
 257   lua_assert(ttype(t1) == ttype(t2));
 258   switch (ttype(t1)) {
 259     case LUA_TNIL: return 1;
 260     case LUA_TNUMBER: return luai_numeq(nvalue(t1), nvalue(t2));
 261     case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */
 262     case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
 263     case LUA_TUSERDATA: {
 264       if (uvalue(t1) == uvalue(t2)) return 1;
 265       tm = get_compTM(L, uvalue(t1)->metatable, uvalue(t2)->metatable,
 266                          TM_EQ);
 267       break;  /* will try TM */
 268     }
 269     case LUA_TTABLE: {
 270       if (hvalue(t1) == hvalue(t2)) return 1;
 271       tm = get_compTM(L, hvalue(t1)->metatable, hvalue(t2)->metatable, TM_EQ);
 272       break;  /* will try TM */
 273     }
 274     default: return gcvalue(t1) == gcvalue(t2);
 275   }
 276   if (tm == NULL) return 0;  /* no TM? */
 277   callTMres(L, L->top, tm, t1, t2);  /* call TM */
 278   return !l_isfalse(L->top);
 279 }
 280
 281
 282 void luaV_concat (lua_State *L, int total, int last) {
 283   do {
 284     StkId top = L->base + last + 1;
 285     int n = 2;  /* number of elements handled in this pass (at least 2) */
 286     if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
 287       if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
 288         luaG_concaterror(L, top-2, top-1);
 289     } else if (tsvalue(top-1)->len == 0)  /* second op is empty? */
 290       (void)tostring(L, top - 2);  /* result is first op (as string) */
 291     else {
 292       /* at least two string values; get as many as possible */
 293       size_t tl = tsvalue(top-1)->len;
 294       char *buffer;
 295       int i;
 296       /* collect total length */
 297       for (n = 1; n < total && tostring(L, top-n-1); n++) {
 298         size_t l = tsvalue(top-n-1)->len;
 299         if (l >= MAX_SIZET - tl) luaG_runerror(L, "string length overflow");
 300         tl += l;
 301       }
 302       buffer = luaZ_openspace(L, &G(L)->buff, tl);
 303       tl = 0;
 304       for (i=n; i>0; i--) {  /* concat all strings */
 305         size_t l = tsvalue(top-i)->len;
 306         memcpy(buffer+tl, svalue(top-i), l);
 307         tl += l;
 308       }
 309       setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
 310     }
 311     total -= n-1;  /* got `n' strings to create 1 new */
 312     last -= n-1;
 313   } while (total > 1);  /* repeat until only 1 result left */
 314 }
 315
 316
 317 static void Arith (lua_State *L, StkId ra, const TValue *rb,
 318                    const TValue *rc, TMS op) {
 319   TValue tempb, tempc;
 320   const TValue *b, *c;
 321   if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
 322       (c = luaV_tonumber(rc, &tempc)) != NULL) {
 323     lua_Number nb = nvalue(b), nc = nvalue(c);
 324     switch (op) {
 325       case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;
 326       case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;
 327       case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;
 328       case TM_DIV: setnvalue(ra, luai_numdiv(nb, nc)); break;
 329       case TM_MOD: setnvalue(ra, luai_nummod(nb, nc)); break;
 330       case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;
 331       case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;
 332       default: lua_assert(0); break;
 333     }
 334   }
 335   else if (!call_binTM(L, rb, rc, ra, op))
 336     luaG_aritherror(L, rb, rc);
 337 }
 338
 339
 340
 341 /*
 342 ** some macros for common tasks in `luaV_execute'
 343 */
 344
 345 #define runtime_check(L, c)     { if (!(c)) break; }
 346
 347 #define RA(i)   (base+GETARG_A(i))
 348 /* to be used after possible stack reallocation */
 349 #define RB(i)   check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
 350 #define RC(i)   check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
 351 #define RKB(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
 352         ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
 353 #define RKC(i)  check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
 354         ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
 355 #define KBx(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, k+GETARG_Bx(i))
 356
 357
 358 #define dojump(L,pc,i)  {(pc) += (i); luai_threadyield(L);}
 359
 360
 361 #define Protect(x)      { L->savedpc = pc; {x;}; base = L->base; }
 362
 363
 364 #define arith_op(op,tm) { \
 365         TValue *rb = RKB(i); \
 366         TValue *rc = RKC(i); \
 367         if (ttisnumber(rb) && ttisnumber(rc)) { \
 368           lua_Number nb = nvalue(rb), nc = nvalue(rc); \
 369           setnvalue(ra, op(nb, nc)); \
 370         } \
 371         else \
 372           Protect(Arith(L, ra, rb, rc, tm)); \
 373       }
 374
 375
 376
 377 void luaV_execute (lua_State *L, int nexeccalls) {
 378   LClosure *cl;
 379   StkId base;
 380   TValue *k;
 381   const Instruction *pc;
 382  reentry:  /* entry point */
 383   lua_assert(isLua(L->ci));
 384   pc = L->savedpc;
 385   cl = &clvalue(L->ci->func)->l;
 386   base = L->base;
 387   k = cl->p->k;
 388   /* main loop of interpreter */
 389   for (;;) {
 390     const Instruction i = *pc++;
 391     StkId ra;
 392     if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&
 393         (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {
 394       traceexec(L, pc);
 395       if (L->status == LUA_YIELD) {  /* did hook yield? */
 396         L->savedpc = pc - 1;
 397         return;
 398       }
 399       base = L->base;
 400     }
 401     /* warning!! several calls may realloc the stack and invalidate `ra' */
 402     ra = RA(i);
 403     lua_assert(base == L->base && L->base == L->ci->base);
 404     lua_assert(base <= L->top && L->top <= L->stack + L->stacksize);
 405     lua_assert(L->top == L->ci->top || luaG_checkopenop(i));
 406     switch (GET_OPCODE(i)) {
 407       case OP_MOVE: {
 408         setobjs2s(L, ra, RB(i));
 409         continue;
 410       }
 411       case OP_LOADK: {
 412         setobj2s(L, ra, KBx(i));
 413         continue;
 414       }
 415       case OP_LOADBOOL: {
 416         setbvalue(ra, GETARG_B(i));
 417         if (GETARG_C(i)) pc++;  /* skip next instruction (if C) */
 418         continue;
 419       }
 420       case OP_LOADNIL: {
 421         TValue *rb = RB(i);
 422         do {
 423           setnilvalue(rb--);
 424         } while (rb >= ra);
 425         continue;
 426       }
 427       case OP_GETUPVAL: {
 428         int b = GETARG_B(i);
 429         setobj2s(L, ra, cl->upvals[b]->v);
 430         continue;
 431       }
 432       case OP_GETGLOBAL: {
 433         TValue g;
 434         TValue *rb = KBx(i);
 435         sethvalue(L, &g, cl->env);
 436         lua_assert(ttisstring(rb));
 437         Protect(luaV_gettable(L, &g, rb, ra));
 438         continue;
 439       }
 440       case OP_GETTABLE: {
 441         Protect(luaV_gettable(L, RB(i), RKC(i), ra));
 442         continue;
 443       }
 444       case OP_SETGLOBAL: {
 445         TValue g;
 446         sethvalue(L, &g, cl->env);
 447         lua_assert(ttisstring(KBx(i)));
 448         Protect(luaV_settable(L, &g, KBx(i), ra));
 449         continue;
 450       }
 451       case OP_SETUPVAL: {
 452         UpVal *uv = cl->upvals[GETARG_B(i)];
 453         setobj(L, uv->v, ra);
 454         luaC_barrier(L, uv, ra);
 455         continue;
 456       }
 457       case OP_SETTABLE: {
 458         Protect(luaV_settable(L, ra, RKB(i), RKC(i)));
 459         continue;
 460       }
 461       case OP_NEWTABLE: {
 462         int b = GETARG_B(i);
 463         int c = GETARG_C(i);
 464         sethvalue(L, ra, luaH_new(L, luaO_fb2int(b), luaO_fb2int(c)));
 465         Protect(luaC_checkGC(L));
 466         continue;
 467       }
 468       case OP_SELF: {
 469         StkId rb = RB(i);
 470         setobjs2s(L, ra+1, rb);
 471         Protect(luaV_gettable(L, rb, RKC(i), ra));
 472         continue;
 473       }
 474       case OP_ADD: {
 475         arith_op(luai_numadd, TM_ADD);
 476         continue;
 477       }
 478       case OP_SUB: {
 479         arith_op(luai_numsub, TM_SUB);
 480         continue;
 481       }
 482       case OP_MUL: {
 483         arith_op(luai_nummul, TM_MUL);
 484         continue;
 485       }
 486       case OP_DIV: {
 487         arith_op(luai_numdiv, TM_DIV);
 488         continue;
 489       }
 490       case OP_MOD: {
 491         arith_op(luai_nummod, TM_MOD);
 492         continue;
 493       }
 494       case OP_POW: {
 495         arith_op(luai_numpow, TM_POW);
 496         continue;
 497       }
 498       case OP_UNM: {
 499         TValue *rb = RB(i);
 500         if (ttisnumber(rb)) {
 501           lua_Number nb = nvalue(rb);
 502           setnvalue(ra, luai_numunm(nb));
 503         }
 504         else {
 505           Protect(Arith(L, ra, rb, rb, TM_UNM));
 506         }
 507         continue;
 508       }
 509       case OP_NOT: {
 510         int res = l_isfalse(RB(i));  /* next assignment may change this value */
 511         setbvalue(ra, res);
 512         continue;
 513       }
 514       case OP_LEN: {
 515         const TValue *rb = RB(i);
 516         switch (ttype(rb)) {
 517           case LUA_TTABLE: {
 518             setnvalue(ra, cast_num(luaH_getn(hvalue(rb))));
 519             break;
 520           }
 521           case LUA_TSTRING: {
 522             setnvalue(ra, cast_num(tsvalue(rb)->len));
 523             break;
 524           }
 525           default: {  /* try metamethod */
 526             Protect(
 527               if (!call_binTM(L, rb, luaO_nilobject, ra, TM_LEN))
 528                 luaG_typeerror(L, rb, "get length of");
 529             )
 530           }
 531         }
 532         continue;
 533       }
 534       case OP_CONCAT: {
 535         int b = GETARG_B(i);
 536         int c = GETARG_C(i);
 537         Protect(luaV_concat(L, c-b+1, c); luaC_checkGC(L));
 538         setobjs2s(L, RA(i), base+b);
 539         continue;
 540       }
 541       case OP_JMP: {
 542         dojump(L, pc, GETARG_sBx(i));
 543         continue;
 544       }
 545       case OP_EQ: {
 546         TValue *rb = RKB(i);
 547         TValue *rc = RKC(i);
 548         Protect(
 549           if (equalobj(L, rb, rc) == GETARG_A(i))
 550             dojump(L, pc, GETARG_sBx(*pc));
 551         )
 552         pc++;
 553         continue;
 554       }
 555       case OP_LT: {
 556         Protect(
 557           if (luaV_lessthan(L, RKB(i), RKC(i)) == GETARG_A(i))
 558             dojump(L, pc, GETARG_sBx(*pc));
 559         )
 560         pc++;
 561         continue;
 562       }
 563       case OP_LE: {
 564         Protect(
 565           if (lessequal(L, RKB(i), RKC(i)) == GETARG_A(i))
 566             dojump(L, pc, GETARG_sBx(*pc));
 567         )
 568         pc++;
 569         continue;
 570       }
 571       case OP_TEST: {
 572         if (l_isfalse(ra) != GETARG_C(i))
 573           dojump(L, pc, GETARG_sBx(*pc));
 574         pc++;
 575         continue;
 576       }
 577       case OP_TESTSET: {
 578         TValue *rb = RB(i);
 579         if (l_isfalse(rb) != GETARG_C(i)) {
 580           setobjs2s(L, ra, rb);
 581           dojump(L, pc, GETARG_sBx(*pc));
 582         }
 583         pc++;
 584         continue;
 585       }
 586       case OP_CALL: {
 587         int b = GETARG_B(i);
 588         int nresults = GETARG_C(i) - 1;
 589         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 590         L->savedpc = pc;
 591         switch (luaD_precall(L, ra, nresults)) {
 592           case PCRLUA: {
 593             nexeccalls++;
 594             goto reentry;  /* restart luaV_execute over new Lua function */
 595           }
 596           case PCRC: {
 597             /* it was a C function (`precall' called it); adjust results */
 598             if (nresults >= 0) L->top = L->ci->top;
 599             base = L->base;
 600             continue;
 601           }
 602           default: {
 603             return;  /* yield */
 604           }
 605         }
 606       }
 607       case OP_TAILCALL: {
 608         int b = GETARG_B(i);
 609         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 610         L->savedpc = pc;
 611         lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
 612         switch (luaD_precall(L, ra, LUA_MULTRET)) {
 613           case PCRLUA: {
 614             /* tail call: put new frame in place of previous one */
 615             CallInfo *ci = L->ci - 1;  /* previous frame */
 616             int aux;
 617             StkId func = ci->func;
 618             StkId pfunc = (ci+1)->func;  /* previous function index */
 619             if (L->openupval) luaF_close(L, ci->base);
 620             L->base = ci->base = ci->func + ((ci+1)->base - pfunc);
 621             for (aux = 0; pfunc+aux < L->top; aux++)  /* move frame down */
 622               setobjs2s(L, func+aux, pfunc+aux);
 623             ci->top = L->top = func+aux;  /* correct top */
 624             lua_assert(L->top == L->base + clvalue(func)->l.p->maxstacksize);
 625             ci->savedpc = L->savedpc;
 626             ci->tailcalls++;  /* one more call lost */
 627             L->ci--;  /* remove new frame */
 628             goto reentry;
 629           }
 630           case PCRC: {  /* it was a C function (`precall' called it) */
 631             base = L->base;
 632             continue;
 633           }
 634           default: {
 635             return;  /* yield */
 636           }
 637         }
 638       }
 639       case OP_RETURN: {
 640         int b = GETARG_B(i);
 641         if (b != 0) L->top = ra+b-1;
 642         if (L->openupval) luaF_close(L, base);
 643         L->savedpc = pc;
 644         b = luaD_poscall(L, ra);
 645         if (--nexeccalls == 0)  /* was previous function running `here'? */
 646           return;  /* no: return */
 647         else {  /* yes: continue its execution */
 648           if (b) L->top = L->ci->top;
 649           lua_assert(isLua(L->ci));
 650           lua_assert(GET_OPCODE(*((L->ci)->savedpc - 1)) == OP_CALL);
 651           goto reentry;
 652         }
 653       }
 654       case OP_FORLOOP: {
 655         lua_Number step = nvalue(ra+2);
 656         lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */
 657         lua_Number limit = nvalue(ra+1);
 658         if (luai_numlt(0, step) ? luai_numle(idx, limit)
 659                                 : luai_numle(limit, idx)) {
 660           dojump(L, pc, GETARG_sBx(i));  /* jump back */
 661           setnvalue(ra, idx);  /* update internal index... */
 662           setnvalue(ra+3, idx);  /* ...and external index */
 663         }
 664         continue;
 665       }
 666       case OP_FORPREP: {
 667         const TValue *init = ra;
 668         const TValue *plimit = ra+1;
 669         const TValue *pstep = ra+2;
 670         L->savedpc = pc;  /* next steps may throw errors */
 671         if (!tonumber(init, ra))
 672           luaG_runerror(L, LUA_QL("for") " initial value must be a number");
 673         else if (!tonumber(plimit, ra+1))
 674           luaG_runerror(L, LUA_QL("for") " limit must be a number");
 675         else if (!tonumber(pstep, ra+2))
 676           luaG_runerror(L, LUA_QL("for") " step must be a number");
 677         setnvalue(ra, luai_numsub(nvalue(ra), nvalue(pstep)));
 678         dojump(L, pc, GETARG_sBx(i));
 679         continue;
 680       }
 681       case OP_TFORLOOP: {
 682         StkId cb = ra + 3;  /* call base */
 683         setobjs2s(L, cb+2, ra+2);
 684         setobjs2s(L, cb+1, ra+1);
 685         setobjs2s(L, cb, ra);
 686         L->top = cb+3;  /* func. + 2 args (state and index) */
 687         Protect(luaD_call(L, cb, GETARG_C(i)));
 688         L->top = L->ci->top;
 689         cb = RA(i) + 3;  /* previous call may change the stack */
 690         if (!ttisnil(cb)) {  /* continue loop? */
 691           setobjs2s(L, cb-1, cb);  /* save control variable */
 692           dojump(L, pc, GETARG_sBx(*pc));  /* jump back */
 693         }
 694         pc++;
 695         continue;
 696       }
 697       case OP_SETLIST: {
 698         int n = GETARG_B(i);
 699         int c = GETARG_C(i);
 700         int last;
 701         Table *h;
 702         if (n == 0) {
 703           n = cast_int(L->top - ra) - 1;
 704           L->top = L->ci->top;
 705         }
 706         if (c == 0) c = cast_int(*pc++);
 707         runtime_check(L, ttistable(ra));
 708         h = hvalue(ra);
 709         last = ((c-1)*LFIELDS_PER_FLUSH) + n;
 710         if (last > h->sizearray)  /* needs more space? */
 711           luaH_resizearray(L, h, last);  /* pre-alloc it at once */
 712         for (; n > 0; n--) {
 713           TValue *val = ra+n;
 714           setobj2t(L, luaH_setnum(L, h, last--), val);
 715           luaC_barriert(L, h, val);
 716         }
 717         continue;
 718       }
 719       case OP_CLOSE: {
 720         luaF_close(L, ra);
 721         continue;
 722       }
 723       case OP_CLOSURE: {
 724         Proto *p;
 725         Closure *ncl;
 726         int nup, j;
 727         p = cl->p->p[GETARG_Bx(i)];
 728         nup = p->nups;
 729         ncl = luaF_newLclosure(L, nup, cl->env);
 730         ncl->l.p = p;
 731         for (j=0; j<nup; j++, pc++) {
 732           if (GET_OPCODE(*pc) == OP_GETUPVAL)
 733             ncl->l.upvals[j] = cl->upvals[GETARG_B(*pc)];
 734           else {
 735             lua_assert(GET_OPCODE(*pc) == OP_MOVE);
 736             ncl->l.upvals[j] = luaF_findupval(L, base + GETARG_B(*pc));
 737           }
 738         }
 739         setclvalue(L, ra, ncl);
 740         Protect(luaC_checkGC(L));
 741         continue;
 742       }
 743       case OP_VARARG: {
 744         int b = GETARG_B(i) - 1;
 745         int j;
 746         CallInfo *ci = L->ci;
 747         int n = cast_int(ci->base - ci->func) - cl->p->numparams - 1;
 748         if (b == LUA_MULTRET) {
 749           Protect(luaD_checkstack(L, n));
 750           ra = RA(i);  /* previous call may change the stack */
 751           b = n;
 752           L->top = ra + n;
 753         }
 754         for (j = 0; j < b; j++) {
 755           if (j < n) {
 756             setobjs2s(L, ra + j, ci->base - n + j);
 757           }
 758           else {
 759             setnilvalue(ra + j);
 760           }
 761         }
 762         continue;
 763       }
 764     }
 765   }
 766 }
 767