external/mit/lua/dist/src/lvm.c

   1 /*      $NetBSD: lvm.c,v 1.1.1.2 2012/03/15 00:08:05 alnsn Exp $        */
   2
   3 /*
   4 ** $Id: lvm.c,v 1.1.1.2 2012/03/15 00:08:05 alnsn Exp $
   5 ** Lua virtual machine
   6 ** See Copyright Notice in lua.h
   7 */
   8
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13
  14 #define lvm_c
  15 #define LUA_CORE
  16
  17 #include "lua.h"
  18
  19 #include "ldebug.h"
  20 #include "ldo.h"
  21 #include "lfunc.h"
  22 #include "lgc.h"
  23 #include "lobject.h"
  24 #include "lopcodes.h"
  25 #include "lstate.h"
  26 #include "lstring.h"
  27 #include "ltable.h"
  28 #include "ltm.h"
  29 #include "lvm.h"
  30
  31
  32
  33 /* limit for table tag-method chains (to avoid loops) */
  34 #define MAXTAGLOOP      100
  35
  36
  37 const TValue *luaV_tonumber (const TValue *obj, TValue *n) {
  38   lua_Number num;
  39   if (ttisnumber(obj)) return obj;
  40   if (ttisstring(obj) && luaO_str2d(svalue(obj), &num)) {
  41     setnvalue(n, num);
  42     return n;
  43   }
  44   else
  45     return NULL;
  46 }
  47
  48
  49 int luaV_tostring (lua_State *L, StkId obj) {
  50   if (!ttisnumber(obj))
  51     return 0;
  52   else {
  53     char s[LUAI_MAXNUMBER2STR];
  54     lua_Number n = nvalue(obj);
  55     lua_number2str(s, n);
  56     setsvalue2s(L, obj, luaS_new(L, s));
  57     return 1;
  58   }
  59 }
  60
  61
  62 static void traceexec (lua_State *L, const Instruction *pc) {
  63   lu_byte mask = L->hookmask;
  64   const Instruction *oldpc = L->savedpc;
  65   L->savedpc = pc;
  66   if ((mask & LUA_MASKCOUNT) && L->hookcount == 0) {
  67     resethookcount(L);
  68     luaD_callhook(L, LUA_HOOKCOUNT, -1);
  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   TValue temp;
 139   for (loop = 0; loop < MAXTAGLOOP; loop++) {
 140     const TValue *tm;
 141     if (ttistable(t)) {  /* `t' is a table? */
 142       Table *h = hvalue(t);
 143       TValue *oldval = luaH_set(L, h, key); /* do a primitive set */
 144       if (!ttisnil(oldval) ||  /* result is no nil? */
 145           (tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL) { /* or no TM? */
 146         setobj2t(L, oldval, val);
 147         h->flags = 0;
 148         luaC_barriert(L, h, val);
 149         return;
 150       }
 151       /* else will try the tag method */
 152     }
 153     else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
 154       luaG_typeerror(L, t, "index");
 155     if (ttisfunction(tm)) {
 156       callTM(L, tm, t, key, val);
 157       return;
 158     }
 159     /* else repeat with `tm' */
 160     setobj(L, &temp, tm);  /* avoid pointing inside table (may rehash) */
 161     t = &temp;
 162   }
 163   luaG_runerror(L, "loop in settable");
 164 }
 165
 166
 167 static int call_binTM (lua_State *L, const TValue *p1, const TValue *p2,
 168                        StkId res, TMS event) {
 169   const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */
 170   if (ttisnil(tm))
 171     tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
 172   if (ttisnil(tm)) return 0;
 173   callTMres(L, res, tm, p1, p2);
 174   return 1;
 175 }
 176
 177
 178 static const TValue *get_compTM (lua_State *L, Table *mt1, Table *mt2,
 179                                   TMS event) {
 180   const TValue *tm1 = fasttm(L, mt1, event);
 181   const TValue *tm2;
 182   if (tm1 == NULL) return NULL;  /* no metamethod */
 183   if (mt1 == mt2) return tm1;  /* same metatables => same metamethods */
 184   tm2 = fasttm(L, mt2, event);
 185   if (tm2 == NULL) return NULL;  /* no metamethod */
 186   if (luaO_rawequalObj(tm1, tm2))  /* same metamethods? */
 187     return tm1;
 188   return NULL;
 189 }
 190
 191
 192 static int call_orderTM (lua_State *L, const TValue *p1, const TValue *p2,
 193                          TMS event) {
 194   const TValue *tm1 = luaT_gettmbyobj(L, p1, event);
 195   const TValue *tm2;
 196   if (ttisnil(tm1)) return -1;  /* no metamethod? */
 197   tm2 = luaT_gettmbyobj(L, p2, event);
 198   if (!luaO_rawequalObj(tm1, tm2))  /* different metamethods? */
 199     return -1;
 200   callTMres(L, L->top, tm1, p1, p2);
 201   return !l_isfalse(L->top);
 202 }
 203
 204
 205 static int l_strcmp (const TString *ls, const TString *rs) {
 206   const char *l = getstr(ls);
 207   size_t ll = ls->tsv.len;
 208   const char *r = getstr(rs);
 209   size_t lr = rs->tsv.len;
 210   for (;;) {
 211     int temp = strcoll(l, r);
 212     if (temp != 0) return temp;
 213     else {  /* strings are equal up to a `\0' */
 214       size_t len = strlen(l);  /* index of first `\0' in both strings */
 215       if (len == lr)  /* r is finished? */
 216         return (len == ll) ? 0 : 1;
 217       else if (len == ll)  /* l is finished? */
 218         return -1;  /* l is smaller than r (because r is not finished) */
 219       /* both strings longer than `len'; go on comparing (after the `\0') */
 220       len++;
 221       l += len; ll -= len; r += len; lr -= len;
 222     }
 223   }
 224 }
 225
 226
 227 int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
 228   int res;
 229   if (ttype(l) != ttype(r))
 230     return luaG_ordererror(L, l, r);
 231   else if (ttisnumber(l))
 232     return luai_numlt(nvalue(l), nvalue(r));
 233   else if (ttisstring(l))
 234     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) < 0;
 235   else if ((res = call_orderTM(L, l, r, TM_LT)) != -1)
 236     return res;
 237   return luaG_ordererror(L, l, r);
 238 }
 239
 240
 241 static int lessequal (lua_State *L, const TValue *l, const TValue *r) {
 242   int res;
 243   if (ttype(l) != ttype(r))
 244     return luaG_ordererror(L, l, r);
 245   else if (ttisnumber(l))
 246     return luai_numle(nvalue(l), nvalue(r));
 247   else if (ttisstring(l))
 248     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) <= 0;
 249   else if ((res = call_orderTM(L, l, r, TM_LE)) != -1)  /* first try `le' */
 250     return res;
 251   else if ((res = call_orderTM(L, r, l, TM_LT)) != -1)  /* else try `lt' */
 252     return !res;
 253   return luaG_ordererror(L, l, r);
 254 }
 255
 256
 257 int luaV_equalval (lua_State *L, const TValue *t1, const TValue *t2) {
 258   const TValue *tm;
 259   lua_assert(ttype(t1) == ttype(t2));
 260   switch (ttype(t1)) {
 261     case LUA_TNIL: return 1;
 262     case LUA_TNUMBER: return luai_numeq(nvalue(t1), nvalue(t2));
 263     case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */
 264     case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
 265     case LUA_TUSERDATA: {
 266       if (uvalue(t1) == uvalue(t2)) return 1;
 267       tm = get_compTM(L, uvalue(t1)->metatable, uvalue(t2)->metatable,
 268                          TM_EQ);
 269       break;  /* will try TM */
 270     }
 271     case LUA_TTABLE: {
 272       if (hvalue(t1) == hvalue(t2)) return 1;
 273       tm = get_compTM(L, hvalue(t1)->metatable, hvalue(t2)->metatable, TM_EQ);
 274       break;  /* will try TM */
 275     }
 276     default: return gcvalue(t1) == gcvalue(t2);
 277   }
 278   if (tm == NULL) return 0;  /* no TM? */
 279   callTMres(L, L->top, tm, t1, t2);  /* call TM */
 280   return !l_isfalse(L->top);
 281 }
 282
 283
 284 void luaV_concat (lua_State *L, int total, int last) {
 285   do {
 286     StkId top = L->base + last + 1;
 287     int n = 2;  /* number of elements handled in this pass (at least 2) */
 288     if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
 289       if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
 290         luaG_concaterror(L, top-2, top-1);
 291     } else if (tsvalue(top-1)->len == 0)  /* second op is empty? */
 292       (void)tostring(L, top - 2);  /* result is first op (as string) */
 293     else {
 294       /* at least two string values; get as many as possible */
 295       size_t tl = tsvalue(top-1)->len;
 296       char *buffer;
 297       int i;
 298       /* collect total length */
 299       for (n = 1; n < total && tostring(L, top-n-1); n++) {
 300         size_t l = tsvalue(top-n-1)->len;
 301         if (l >= MAX_SIZET - tl) luaG_runerror(L, "string length overflow");
 302         tl += l;
 303       }
 304       buffer = luaZ_openspace(L, &G(L)->buff, tl);
 305       tl = 0;
 306       for (i=n; i>0; i--) {  /* concat all strings */
 307         size_t l = tsvalue(top-i)->len;
 308         memcpy(buffer+tl, svalue(top-i), l);
 309         tl += l;
 310       }
 311       setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
 312     }
 313     total -= n-1;  /* got `n' strings to create 1 new */
 314     last -= n-1;
 315   } while (total > 1);  /* repeat until only 1 result left */
 316 }
 317
 318
 319 static void Arith (lua_State *L, StkId ra, const TValue *rb,
 320                    const TValue *rc, TMS op) {
 321   TValue tempb, tempc;
 322   const TValue *b, *c;
 323   if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
 324       (c = luaV_tonumber(rc, &tempc)) != NULL) {
 325     lua_Number nb = nvalue(b), nc = nvalue(c);
 326     switch (op) {
 327       case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;
 328       case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;
 329       case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;
 330       case TM_DIV: setnvalue(ra, luai_numdiv(nb, nc)); break;
 331       case TM_MOD: setnvalue(ra, luai_nummod(nb, nc)); break;
 332       case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;
 333       case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;
 334       default: lua_assert(0); break;
 335     }
 336   }
 337   else if (!call_binTM(L, rb, rc, ra, op))
 338     luaG_aritherror(L, rb, rc);
 339 }
 340
 341
 342
 343 /*
 344 ** some macros for common tasks in `luaV_execute'
 345 */
 346
 347 #define runtime_check(L, c)     { if (!(c)) break; }
 348
 349 #define RA(i)   (base+GETARG_A(i))
 350 /* to be used after possible stack reallocation */
 351 #define RB(i)   check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
 352 #define RC(i)   check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
 353 #define RKB(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
 354         ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
 355 #define RKC(i)  check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
 356         ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
 357 #define KBx(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, k+GETARG_Bx(i))
 358
 359
 360 #define dojump(L,pc,i)  {(pc) += (i); luai_threadyield(L);}
 361
 362
 363 #define Protect(x)      { L->savedpc = pc; {x;}; base = L->base; }
 364
 365
 366 #define arith_op(op,tm) { \
 367         TValue *rb = RKB(i); \
 368         TValue *rc = RKC(i); \
 369         if (ttisnumber(rb) && ttisnumber(rc)) { \
 370           lua_Number nb = nvalue(rb), nc = nvalue(rc); \
 371           setnvalue(ra, op(nb, nc)); \
 372         } \
 373         else \
 374           Protect(Arith(L, ra, rb, rc, tm)); \
 375       }
 376
 377
 378
 379 void luaV_execute (lua_State *L, int nexeccalls) {
 380   LClosure *cl;
 381   StkId base;
 382   TValue *k;
 383   const Instruction *pc;
 384  reentry:  /* entry point */
 385   lua_assert(isLua(L->ci));
 386   pc = L->savedpc;
 387   cl = &clvalue(L->ci->func)->l;
 388   base = L->base;
 389   k = cl->p->k;
 390   /* main loop of interpreter */
 391   for (;;) {
 392     const Instruction i = *pc++;
 393     StkId ra;
 394     if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&
 395         (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {
 396       traceexec(L, pc);
 397       if (L->status == LUA_YIELD) {  /* did hook yield? */
 398         L->savedpc = pc - 1;
 399         return;
 400       }
 401       base = L->base;
 402     }
 403     /* warning!! several calls may realloc the stack and invalidate `ra' */
 404     ra = RA(i);
 405     lua_assert(base == L->base && L->base == L->ci->base);
 406     lua_assert(base <= L->top && L->top <= L->stack + L->stacksize);
 407     lua_assert(L->top == L->ci->top || luaG_checkopenop(i));
 408     switch (GET_OPCODE(i)) {
 409       case OP_MOVE: {
 410         setobjs2s(L, ra, RB(i));
 411         continue;
 412       }
 413       case OP_LOADK: {
 414         setobj2s(L, ra, KBx(i));
 415         continue;
 416       }
 417       case OP_LOADBOOL: {
 418         setbvalue(ra, GETARG_B(i));
 419         if (GETARG_C(i)) pc++;  /* skip next instruction (if C) */
 420         continue;
 421       }
 422       case OP_LOADNIL: {
 423         TValue *rb = RB(i);
 424         do {
 425           setnilvalue(rb--);
 426         } while (rb >= ra);
 427         continue;
 428       }
 429       case OP_GETUPVAL: {
 430         int b = GETARG_B(i);
 431         setobj2s(L, ra, cl->upvals[b]->v);
 432         continue;
 433       }
 434       case OP_GETGLOBAL: {
 435         TValue g;
 436         TValue *rb = KBx(i);
 437         sethvalue(L, &g, cl->env);
 438         lua_assert(ttisstring(rb));
 439         Protect(luaV_gettable(L, &g, rb, ra));
 440         continue;
 441       }
 442       case OP_GETTABLE: {
 443         Protect(luaV_gettable(L, RB(i), RKC(i), ra));
 444         continue;
 445       }
 446       case OP_SETGLOBAL: {
 447         TValue g;
 448         sethvalue(L, &g, cl->env);
 449         lua_assert(ttisstring(KBx(i)));
 450         Protect(luaV_settable(L, &g, KBx(i), ra));
 451         continue;
 452       }
 453       case OP_SETUPVAL: {
 454         UpVal *uv = cl->upvals[GETARG_B(i)];
 455         setobj(L, uv->v, ra);
 456         luaC_barrier(L, uv, ra);
 457         continue;
 458       }
 459       case OP_SETTABLE: {
 460         Protect(luaV_settable(L, ra, RKB(i), RKC(i)));
 461         continue;
 462       }
 463       case OP_NEWTABLE: {
 464         int b = GETARG_B(i);
 465         int c = GETARG_C(i);
 466         sethvalue(L, ra, luaH_new(L, luaO_fb2int(b), luaO_fb2int(c)));
 467         Protect(luaC_checkGC(L));
 468         continue;
 469       }
 470       case OP_SELF: {
 471         StkId rb = RB(i);
 472         setobjs2s(L, ra+1, rb);
 473         Protect(luaV_gettable(L, rb, RKC(i), ra));
 474         continue;
 475       }
 476       case OP_ADD: {
 477         arith_op(luai_numadd, TM_ADD);
 478         continue;
 479       }
 480       case OP_SUB: {
 481         arith_op(luai_numsub, TM_SUB);
 482         continue;
 483       }
 484       case OP_MUL: {
 485         arith_op(luai_nummul, TM_MUL);
 486         continue;
 487       }
 488       case OP_DIV: {
 489         arith_op(luai_numdiv, TM_DIV);
 490         continue;
 491       }
 492       case OP_MOD: {
 493         arith_op(luai_nummod, TM_MOD);
 494         continue;
 495       }
 496       case OP_POW: {
 497         arith_op(luai_numpow, TM_POW);
 498         continue;
 499       }
 500       case OP_UNM: {
 501         TValue *rb = RB(i);
 502         if (ttisnumber(rb)) {
 503           lua_Number nb = nvalue(rb);
 504           setnvalue(ra, luai_numunm(nb));
 505         }
 506         else {
 507           Protect(Arith(L, ra, rb, rb, TM_UNM));
 508         }
 509         continue;
 510       }
 511       case OP_NOT: {
 512         int res = l_isfalse(RB(i));  /* next assignment may change this value */
 513         setbvalue(ra, res);
 514         continue;
 515       }
 516       case OP_LEN: {
 517         const TValue *rb = RB(i);
 518         switch (ttype(rb)) {
 519           case LUA_TTABLE: {
 520             setnvalue(ra, cast_num(luaH_getn(hvalue(rb))));
 521             break;
 522           }
 523           case LUA_TSTRING: {
 524             setnvalue(ra, cast_num(tsvalue(rb)->len));
 525             break;
 526           }
 527           default: {  /* try metamethod */
 528             Protect(
 529               if (!call_binTM(L, rb, luaO_nilobject, ra, TM_LEN))
 530                 luaG_typeerror(L, rb, "get length of");
 531             )
 532           }
 533         }
 534         continue;
 535       }
 536       case OP_CONCAT: {
 537         int b = GETARG_B(i);
 538         int c = GETARG_C(i);
 539         Protect(luaV_concat(L, c-b+1, c); luaC_checkGC(L));
 540         setobjs2s(L, RA(i), base+b);
 541         continue;
 542       }
 543       case OP_JMP: {
 544         dojump(L, pc, GETARG_sBx(i));
 545         continue;
 546       }
 547       case OP_EQ: {
 548         TValue *rb = RKB(i);
 549         TValue *rc = RKC(i);
 550         Protect(
 551           if (equalobj(L, rb, rc) == GETARG_A(i))
 552             dojump(L, pc, GETARG_sBx(*pc));
 553         )
 554         pc++;
 555         continue;
 556       }
 557       case OP_LT: {
 558         Protect(
 559           if (luaV_lessthan(L, RKB(i), RKC(i)) == GETARG_A(i))
 560             dojump(L, pc, GETARG_sBx(*pc));
 561         )
 562         pc++;
 563         continue;
 564       }
 565       case OP_LE: {
 566         Protect(
 567           if (lessequal(L, RKB(i), RKC(i)) == GETARG_A(i))
 568             dojump(L, pc, GETARG_sBx(*pc));
 569         )
 570         pc++;
 571         continue;
 572       }
 573       case OP_TEST: {
 574         if (l_isfalse(ra) != GETARG_C(i))
 575           dojump(L, pc, GETARG_sBx(*pc));
 576         pc++;
 577         continue;
 578       }
 579       case OP_TESTSET: {
 580         TValue *rb = RB(i);
 581         if (l_isfalse(rb) != GETARG_C(i)) {
 582           setobjs2s(L, ra, rb);
 583           dojump(L, pc, GETARG_sBx(*pc));
 584         }
 585         pc++;
 586         continue;
 587       }
 588       case OP_CALL: {
 589         int b = GETARG_B(i);
 590         int nresults = GETARG_C(i) - 1;
 591         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 592         L->savedpc = pc;
 593         switch (luaD_precall(L, ra, nresults)) {
 594           case PCRLUA: {
 595             nexeccalls++;
 596             goto reentry;  /* restart luaV_execute over new Lua function */
 597           }
 598           case PCRC: {
 599             /* it was a C function (`precall' called it); adjust results */
 600             if (nresults >= 0) L->top = L->ci->top;
 601             base = L->base;
 602             continue;
 603           }
 604           default: {
 605             return;  /* yield */
 606           }
 607         }
 608       }
 609       case OP_TAILCALL: {
 610         int b = GETARG_B(i);
 611         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
 612         L->savedpc = pc;
 613         lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
 614         switch (luaD_precall(L, ra, LUA_MULTRET)) {
 615           case PCRLUA: {
 616             /* tail call: put new frame in place of previous one */
 617             CallInfo *ci = L->ci - 1;  /* previous frame */
 618             int aux;
 619             StkId func = ci->func;
 620             StkId pfunc = (ci+1)->func;  /* previous function index */
 621             if (L->openupval) luaF_close(L, ci->base);
 622             L->base = ci->base = ci->func + ((ci+1)->base - pfunc);
 623             for (aux = 0; pfunc+aux < L->top; aux++)  /* move frame down */
 624               setobjs2s(L, func+aux, pfunc+aux);
 625             ci->top = L->top = func+aux;  /* correct top */
 626             lua_assert(L->top == L->base + clvalue(func)->l.p->maxstacksize);
 627             ci->savedpc = L->savedpc;
 628             ci->tailcalls++;  /* one more call lost */
 629             L->ci--;  /* remove new frame */
 630             goto reentry;
 631           }
 632           case PCRC: {  /* it was a C function (`precall' called it) */
 633             base = L->base;
 634             continue;
 635           }
 636           default: {
 637             return;  /* yield */
 638           }
 639         }
 640       }
 641       case OP_RETURN: {
 642         int b = GETARG_B(i);
 643         if (b != 0) L->top = ra+b-1;
 644         if (L->openupval) luaF_close(L, base);
 645         L->savedpc = pc;
 646         b = luaD_poscall(L, ra);
 647         if (--nexeccalls == 0)  /* was previous function running `here'? */
 648           return;  /* no: return */
 649         else {  /* yes: continue its execution */
 650           if (b) L->top = L->ci->top;
 651           lua_assert(isLua(L->ci));
 652           lua_assert(GET_OPCODE(*((L->ci)->savedpc - 1)) == OP_CALL);
 653           goto reentry;
 654         }
 655       }
 656       case OP_FORLOOP: {
 657         lua_Number step = nvalue(ra+2);
 658         lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */
 659         lua_Number limit = nvalue(ra+1);
 660         if (luai_numlt(0, step) ? luai_numle(idx, limit)
 661                                 : luai_numle(limit, idx)) {
 662           dojump(L, pc, GETARG_sBx(i));  /* jump back */
 663           setnvalue(ra, idx);  /* update internal index... */
 664           setnvalue(ra+3, idx);  /* ...and external index */
 665         }
 666         continue;
 667       }
 668       case OP_FORPREP: {
 669         const TValue *init = ra;
 670         const TValue *plimit = ra+1;
 671         const TValue *pstep = ra+2;
 672         L->savedpc = pc;  /* next steps may throw errors */
 673         if (!tonumber(init, ra))
 674           luaG_runerror(L, LUA_QL("for") " initial value must be a number");
 675         else if (!tonumber(plimit, ra+1))
 676           luaG_runerror(L, LUA_QL("for") " limit must be a number");
 677         else if (!tonumber(pstep, ra+2))
 678           luaG_runerror(L, LUA_QL("for") " step must be a number");
 679         setnvalue(ra, luai_numsub(nvalue(ra), nvalue(pstep)));
 680         dojump(L, pc, GETARG_sBx(i));
 681         continue;
 682       }
 683       case OP_TFORLOOP: {
 684         StkId cb = ra + 3;  /* call base */
 685         setobjs2s(L, cb+2, ra+2);
 686         setobjs2s(L, cb+1, ra+1);
 687         setobjs2s(L, cb, ra);
 688         L->top = cb+3;  /* func. + 2 args (state and index) */
 689         Protect(luaD_call(L, cb, GETARG_C(i)));
 690         L->top = L->ci->top;
 691         cb = RA(i) + 3;  /* previous call may change the stack */
 692         if (!ttisnil(cb)) {  /* continue loop? */
 693           setobjs2s(L, cb-1, cb);  /* save control variable */
 694           dojump(L, pc, GETARG_sBx(*pc));  /* jump back */
 695         }
 696         pc++;
 697         continue;
 698       }
 699       case OP_SETLIST: {
 700         int n = GETARG_B(i);
 701         int c = GETARG_C(i);
 702         int last;
 703         Table *h;
 704         if (n == 0) {
 705           n = cast_int(L->top - ra) - 1;
 706           L->top = L->ci->top;
 707         }
 708         if (c == 0) c = cast_int(*pc++);
 709         runtime_check(L, ttistable(ra));
 710         h = hvalue(ra);
 711         last = ((c-1)*LFIELDS_PER_FLUSH) + n;
 712         if (last > h->sizearray)  /* needs more space? */
 713           luaH_resizearray(L, h, last);  /* pre-alloc it at once */
 714         for (; n > 0; n--) {
 715           TValue *val = ra+n;
 716           setobj2t(L, luaH_setnum(L, h, last--), val);
 717           luaC_barriert(L, h, val);
 718         }
 719         continue;
 720       }
 721       case OP_CLOSE: {
 722         luaF_close(L, ra);
 723         continue;
 724       }
 725       case OP_CLOSURE: {
 726         Proto *p;
 727         Closure *ncl;
 728         int nup, j;
 729         p = cl->p->p[GETARG_Bx(i)];
 730         nup = p->nups;
 731         ncl = luaF_newLclosure(L, nup, cl->env);
 732         ncl->l.p = p;
 733         for (j=0; j<nup; j++, pc++) {
 734           if (GET_OPCODE(*pc) == OP_GETUPVAL)
 735             ncl->l.upvals[j] = cl->upvals[GETARG_B(*pc)];
 736           else {
 737             lua_assert(GET_OPCODE(*pc) == OP_MOVE);
 738             ncl->l.upvals[j] = luaF_findupval(L, base + GETARG_B(*pc));
 739           }
 740         }
 741         setclvalue(L, ra, ncl);
 742         Protect(luaC_checkGC(L));
 743         continue;
 744       }
 745       case OP_VARARG: {
 746         int b = GETARG_B(i) - 1;
 747         int j;
 748         CallInfo *ci = L->ci;
 749         int n = cast_int(ci->base - ci->func) - cl->p->numparams - 1;
 750         if (b == LUA_MULTRET) {
 751           Protect(luaD_checkstack(L, n));
 752           ra = RA(i);  /* previous call may change the stack */
 753           b = n;
 754           L->top = ra + n;
 755         }
 756         for (j = 0; j < b; j++) {
 757           if (j < n) {
 758             setobjs2s(L, ra + j, ci->base - n + j);
 759           }
 760           else {
 761             setnilvalue(ra + j);
 762           }
 763         }
 764         continue;
 765       }
 766     }
 767   }
 768 }
 769