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      1 /*
      2 ** $Id: lvm.c,v 2.155 2013/03/16 21:10:18 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), tsvalue(obj)->len, &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     int l = lua_number2str(s, n);
     54     setsvalue2s(L, obj, luaS_newlstr(L, s, l));
     55     return 1;
     56   }
     57 }
     58 
     59 
     60 static void traceexec (lua_State *L) {
     61   CallInfo *ci = L->ci;
     62   lu_byte mask = L->hookmask;
     63   int counthook = ((mask & LUA_MASKCOUNT) && L->hookcount == 0);
     64   if (counthook)
     65     resethookcount(L);  /* reset count */
     66   if (ci->callstatus & CIST_HOOKYIELD) {  /* called hook last time? */
     67     ci->callstatus &= ~CIST_HOOKYIELD;  /* erase mark */
     68     return;  /* do not call hook again (VM yielded, so it did not move) */
     69   }
     70   if (counthook)
     71     luaD_hook(L, LUA_HOOKCOUNT, -1);  /* call count hook */
     72   if (mask & LUA_MASKLINE) {
     73     Proto *p = ci_func(ci)->p;
     74     int npc = pcRel(ci->u.l.savedpc, p);
     75     int newline = getfuncline(p, npc);
     76     if (npc == 0 ||  /* call linehook when enter a new function, */
     77         ci->u.l.savedpc <= L->oldpc ||  /* when jump back (loop), or when */
     78         newline != getfuncline(p, pcRel(L->oldpc, p)))  /* enter a new line */
     79       luaD_hook(L, LUA_HOOKLINE, newline);  /* call line hook */
     80   }
     81   L->oldpc = ci->u.l.savedpc;
     82   if (L->status == LUA_YIELD) {  /* did hook yield? */
     83     if (counthook)
     84       L->hookcount = 1;  /* undo decrement to zero */
     85     ci->u.l.savedpc--;  /* undo increment (resume will increment it again) */
     86     ci->callstatus |= CIST_HOOKYIELD;  /* mark that it yielded */
     87     ci->func = L->top - 1;  /* protect stack below results */
     88     luaD_throw(L, LUA_YIELD);
     89   }
     90 }
     91 
     92 
     93 static void callTM (lua_State *L, const TValue *f, const TValue *p1,
     94                     const TValue *p2, TValue *p3, int hasres) {
     95   ptrdiff_t result = savestack(L, p3);
     96   setobj2s(L, L->top++, f);  /* push function */
     97   setobj2s(L, L->top++, p1);  /* 1st argument */
     98   setobj2s(L, L->top++, p2);  /* 2nd argument */
     99   if (!hasres)  /* no result? 'p3' is third argument */
    100     setobj2s(L, L->top++, p3);  /* 3rd argument */
    101   /* metamethod may yield only when called from Lua code */
    102   luaD_call(L, L->top - (4 - hasres), hasres, isLua(L->ci));
    103   if (hasres) {  /* if has result, move it to its place */
    104     p3 = restorestack(L, result);
    105     setobjs2s(L, p3, --L->top);
    106   }
    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 not 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       callTM(L, tm, t, key, val, 1);
    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 = cast(TValue *, luaH_get(h, key));
    143       /* if previous value is not nil, there must be a previous entry
    144          in the table; moreover, a metamethod has no relevance */
    145       if (!ttisnil(oldval) ||
    146          /* previous value is nil; must check the metamethod */
    147          ((tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL &&
    148          /* no metamethod; is there a previous entry in the table? */
    149          (oldval != luaO_nilobject ||
    150          /* no previous entry; must create one. (The next test is
    151             always true; we only need the assignment.) */
    152          (oldval = luaH_newkey(L, h, key), 1)))) {
    153         /* no metamethod and (now) there is an entry with given key */
    154         setobj2t(L, oldval, val);  /* assign new value to that entry */
    155         invalidateTMcache(h);
    156         luaC_barrierback(L, obj2gco(h), val);
    157         return;
    158       }
    159       /* else will try the metamethod */
    160     }
    161     else  /* not a table; check metamethod */
    162       if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
    163         luaG_typeerror(L, t, "index");
    164     /* there is a metamethod */
    165     if (ttisfunction(tm)) {
    166       callTM(L, tm, t, key, val, 0);
    167       return;
    168     }
    169     t = tm;  /* else repeat with 'tm' */
    170   }
    171   luaG_runerror(L, "loop in settable");
    172 }
    173 
    174 
    175 static int call_binTM (lua_State *L, const TValue *p1, const TValue *p2,
    176                        StkId res, TMS event) {
    177   const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */
    178   if (ttisnil(tm))
    179     tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
    180   if (ttisnil(tm)) return 0;
    181   callTM(L, tm, p1, p2, res, 1);
    182   return 1;
    183 }
    184 
    185 
    186 static const TValue *get_equalTM (lua_State *L, Table *mt1, Table *mt2,
    187                                   TMS event) {
    188   const TValue *tm1 = fasttm(L, mt1, event);
    189   const TValue *tm2;
    190   if (tm1 == NULL) return NULL;  /* no metamethod */
    191   if (mt1 == mt2) return tm1;  /* same metatables => same metamethods */
    192   tm2 = fasttm(L, mt2, event);
    193   if (tm2 == NULL) return NULL;  /* no metamethod */
    194   if (luaV_rawequalobj(tm1, tm2))  /* same metamethods? */
    195     return tm1;
    196   return NULL;
    197 }
    198 
    199 
    200 static int call_orderTM (lua_State *L, const TValue *p1, const TValue *p2,
    201                          TMS event) {
    202   if (!call_binTM(L, p1, p2, L->top, event))
    203     return -1;  /* no metamethod */
    204   else
    205     return !l_isfalse(L->top);
    206 }
    207 
    208 
    209 static int l_strcmp (const TString *ls, const TString *rs) {
    210   const char *l = getstr(ls);
    211   size_t ll = ls->tsv.len;
    212   const char *r = getstr(rs);
    213   size_t lr = rs->tsv.len;
    214   for (;;) {
    215     int temp = strcoll(l, r);
    216     if (temp != 0) return temp;
    217     else {  /* strings are equal up to a `\0' */
    218       size_t len = strlen(l);  /* index of first `\0' in both strings */
    219       if (len == lr)  /* r is finished? */
    220         return (len == ll) ? 0 : 1;
    221       else if (len == ll)  /* l is finished? */
    222         return -1;  /* l is smaller than r (because r is not finished) */
    223       /* both strings longer than `len'; go on comparing (after the `\0') */
    224       len++;
    225       l += len; ll -= len; r += len; lr -= len;
    226     }
    227   }
    228 }
    229 
    230 
    231 int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r) {
    232   int res;
    233   if (ttisnumber(l) && ttisnumber(r))
    234     return luai_numlt(L, nvalue(l), nvalue(r));
    235   else if (ttisstring(l) && ttisstring(r))
    236     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) < 0;
    237   else if ((res = call_orderTM(L, l, r, TM_LT)) < 0)
    238     luaG_ordererror(L, l, r);
    239   return res;
    240 }
    241 
    242 
    243 int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r) {
    244   int res;
    245   if (ttisnumber(l) && ttisnumber(r))
    246     return luai_numle(L, nvalue(l), nvalue(r));
    247   else if (ttisstring(l) && ttisstring(r))
    248     return l_strcmp(rawtsvalue(l), rawtsvalue(r)) <= 0;
    249   else if ((res = call_orderTM(L, l, r, TM_LE)) >= 0)  /* first try `le' */
    250     return res;
    251   else if ((res = call_orderTM(L, r, l, TM_LT)) < 0)  /* else try `lt' */
    252     luaG_ordererror(L, l, r);
    253   return !res;
    254 }
    255 
    256 
    257 /*
    258 ** equality of Lua values. L == NULL means raw equality (no metamethods)
    259 */
    260 int luaV_equalobj_ (lua_State *L, const TValue *t1, const TValue *t2) {
    261   const TValue *tm;
    262   lua_assert(ttisequal(t1, t2));
    263   switch (ttype(t1)) {
    264     case LUA_TNIL: return 1;
    265     case LUA_TNUMBER: return luai_numeq(nvalue(t1), nvalue(t2));
    266     case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */
    267     case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);
    268     case LUA_TLCF: return fvalue(t1) == fvalue(t2);
    269     case LUA_TSHRSTR: return eqshrstr(rawtsvalue(t1), rawtsvalue(t2));
    270     case LUA_TLNGSTR: return luaS_eqlngstr(rawtsvalue(t1), rawtsvalue(t2));
    271     case LUA_TUSERDATA: {
    272       if (uvalue(t1) == uvalue(t2)) return 1;
    273       else if (L == NULL) return 0;
    274       tm = get_equalTM(L, uvalue(t1)->metatable, uvalue(t2)->metatable, TM_EQ);
    275       break;  /* will try TM */
    276     }
    277     case LUA_TTABLE: {
    278       if (hvalue(t1) == hvalue(t2)) return 1;
    279       else if (L == NULL) return 0;
    280       tm = get_equalTM(L, hvalue(t1)->metatable, hvalue(t2)->metatable, TM_EQ);
    281       break;  /* will try TM */
    282     }
    283     default:
    284       lua_assert(iscollectable(t1));
    285       return gcvalue(t1) == gcvalue(t2);
    286   }
    287   if (tm == NULL) return 0;  /* no TM? */
    288   callTM(L, tm, t1, t2, L->top, 1);  /* call TM */
    289   return !l_isfalse(L->top);
    290 }
    291 
    292 
    293 void luaV_concat (lua_State *L, int total) {
    294   lua_assert(total >= 2);
    295   do {
    296     StkId top = L->top;
    297     int n = 2;  /* number of elements handled in this pass (at least 2) */
    298     if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
    299       if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
    300         luaG_concaterror(L, top-2, top-1);
    301     }
    302     else if (tsvalue(top-1)->len == 0)  /* second operand is empty? */
    303       (void)tostring(L, top - 2);  /* result is first operand */
    304     else if (ttisstring(top-2) && tsvalue(top-2)->len == 0) {
    305       setobjs2s(L, top - 2, top - 1);  /* result is second op. */
    306     }
    307     else {
    308       /* at least two non-empty string values; get as many as possible */
    309       size_t tl = tsvalue(top-1)->len;
    310       char *buffer;
    311       int i;
    312       /* collect total length */
    313       for (i = 1; i < total && tostring(L, top-i-1); i++) {
    314         size_t l = tsvalue(top-i-1)->len;
    315         if (l >= (MAX_SIZET/sizeof(char)) - tl)
    316           luaG_runerror(L, "string length overflow");
    317         tl += l;
    318       }
    319       buffer = luaZ_openspace(L, &G(L)->buff, tl);
    320       tl = 0;
    321       n = i;
    322       do {  /* concat all strings */
    323         size_t l = tsvalue(top-i)->len;
    324         memcpy(buffer+tl, svalue(top-i), l * sizeof(char));
    325         tl += l;
    326       } while (--i > 0);
    327       setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
    328     }
    329     total -= n-1;  /* got 'n' strings to create 1 new */
    330     L->top -= n-1;  /* popped 'n' strings and pushed one */
    331   } while (total > 1);  /* repeat until only 1 result left */
    332 }
    333 
    334 
    335 void luaV_objlen (lua_State *L, StkId ra, const TValue *rb) {
    336   const TValue *tm;
    337   switch (ttypenv(rb)) {
    338     case LUA_TTABLE: {
    339       Table *h = hvalue(rb);
    340       tm = fasttm(L, h->metatable, TM_LEN);
    341       if (tm) break;  /* metamethod? break switch to call it */
    342       setnvalue(ra, cast_num(luaH_getn(h)));  /* else primitive len */
    343       return;
    344     }
    345     case LUA_TSTRING: {
    346       setnvalue(ra, cast_num(tsvalue(rb)->len));
    347       return;
    348     }
    349     default: {  /* try metamethod */
    350       tm = luaT_gettmbyobj(L, rb, TM_LEN);
    351       if (ttisnil(tm))  /* no metamethod? */
    352         luaG_typeerror(L, rb, "get length of");
    353       break;
    354     }
    355   }
    356   callTM(L, tm, rb, rb, ra, 1);
    357 }
    358 
    359 
    360 void luaV_arith (lua_State *L, StkId ra, const TValue *rb,
    361                  const TValue *rc, TMS op) {
    362   TValue tempb, tempc;
    363   const TValue *b, *c;
    364   if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
    365       (c = luaV_tonumber(rc, &tempc)) != NULL) {
    366     lua_Number res = luaO_arith(op - TM_ADD + LUA_OPADD, nvalue(b), nvalue(c));
    367     setnvalue(ra, res);
    368   }
    369   else if (!call_binTM(L, rb, rc, ra, op))
    370     luaG_aritherror(L, rb, rc);
    371 }
    372 
    373 
    374 /*
    375 ** check whether cached closure in prototype 'p' may be reused, that is,
    376 ** whether there is a cached closure with the same upvalues needed by
    377 ** new closure to be created.
    378 */
    379 static Closure *getcached (Proto *p, UpVal **encup, StkId base) {
    380   Closure *c = p->cache;
    381   if (c != NULL) {  /* is there a cached closure? */
    382     int nup = p->sizeupvalues;
    383     Upvaldesc *uv = p->upvalues;
    384     int i;
    385     for (i = 0; i < nup; i++) {  /* check whether it has right upvalues */
    386       TValue *v = uv[i].instack ? base + uv[i].idx : encup[uv[i].idx]->v;
    387       if (c->l.upvals[i]->v != v)
    388         return NULL;  /* wrong upvalue; cannot reuse closure */
    389     }
    390   }
    391   return c;  /* return cached closure (or NULL if no cached closure) */
    392 }
    393 
    394 
    395 /*
    396 ** create a new Lua closure, push it in the stack, and initialize
    397 ** its upvalues. Note that the call to 'luaC_barrierproto' must come
    398 ** before the assignment to 'p->cache', as the function needs the
    399 ** original value of that field.
    400 */
    401 static void pushclosure (lua_State *L, Proto *p, UpVal **encup, StkId base,
    402                          StkId ra) {
    403   int nup = p->sizeupvalues;
    404   Upvaldesc *uv = p->upvalues;
    405   int i;
    406   Closure *ncl = luaF_newLclosure(L, nup);
    407   ncl->l.p = p;
    408   setclLvalue(L, ra, ncl);  /* anchor new closure in stack */
    409   for (i = 0; i < nup; i++) {  /* fill in its upvalues */
    410     if (uv[i].instack)  /* upvalue refers to local variable? */
    411       ncl->l.upvals[i] = luaF_findupval(L, base + uv[i].idx);
    412     else  /* get upvalue from enclosing function */
    413       ncl->l.upvals[i] = encup[uv[i].idx];
    414   }
    415   luaC_barrierproto(L, p, ncl);
    416   p->cache = ncl;  /* save it on cache for reuse */
    417 }
    418 
    419 
    420 /*
    421 ** finish execution of an opcode interrupted by an yield
    422 */
    423 void luaV_finishOp (lua_State *L) {
    424   CallInfo *ci = L->ci;
    425   StkId base = ci->u.l.base;
    426   Instruction inst = *(ci->u.l.savedpc - 1);  /* interrupted instruction */
    427   OpCode op = GET_OPCODE(inst);
    428   switch (op) {  /* finish its execution */
    429     case OP_ADD: case OP_SUB: case OP_MUL: case OP_DIV:
    430     case OP_MOD: case OP_POW: case OP_UNM: case OP_LEN:
    431     case OP_GETTABUP: case OP_GETTABLE: case OP_SELF: {
    432       setobjs2s(L, base + GETARG_A(inst), --L->top);
    433       break;
    434     }
    435     case OP_LE: case OP_LT: case OP_EQ: {
    436       int res = !l_isfalse(L->top - 1);
    437       L->top--;
    438       /* metamethod should not be called when operand is K */
    439       lua_assert(!ISK(GETARG_B(inst)));
    440       if (op == OP_LE &&  /* "<=" using "<" instead? */
    441           ttisnil(luaT_gettmbyobj(L, base + GETARG_B(inst), TM_LE)))
    442         res = !res;  /* invert result */
    443       lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_JMP);
    444       if (res != GETARG_A(inst))  /* condition failed? */
    445         ci->u.l.savedpc++;  /* skip jump instruction */
    446       break;
    447     }
    448     case OP_CONCAT: {
    449       StkId top = L->top - 1;  /* top when 'call_binTM' was called */
    450       int b = GETARG_B(inst);      /* first element to concatenate */
    451       int total = cast_int(top - 1 - (base + b));  /* yet to concatenate */
    452       setobj2s(L, top - 2, top);  /* put TM result in proper position */
    453       if (total > 1) {  /* are there elements to concat? */
    454         L->top = top - 1;  /* top is one after last element (at top-2) */
    455         luaV_concat(L, total);  /* concat them (may yield again) */
    456       }
    457       /* move final result to final position */
    458       setobj2s(L, ci->u.l.base + GETARG_A(inst), L->top - 1);
    459       L->top = ci->top;  /* restore top */
    460       break;
    461     }
    462     case OP_TFORCALL: {
    463       lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_TFORLOOP);
    464       L->top = ci->top;  /* correct top */
    465       break;
    466     }
    467     case OP_CALL: {
    468       if (GETARG_C(inst) - 1 >= 0)  /* nresults >= 0? */
    469         L->top = ci->top;  /* adjust results */
    470       break;
    471     }
    472     case OP_TAILCALL: case OP_SETTABUP: case OP_SETTABLE:
    473       break;
    474     default: lua_assert(0);
    475   }
    476 }
    477 
    478 
    479 
    480 /*
    481 ** some macros for common tasks in `luaV_execute'
    482 */
    483 
    484 #if !defined luai_runtimecheck
    485 #define luai_runtimecheck(L, c)		/* void */
    486 #endif
    487 
    488 
    489 #define RA(i)	(base+GETARG_A(i))
    490 /* to be used after possible stack reallocation */
    491 #define RB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
    492 #define RC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
    493 #define RKB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
    494 	ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
    495 #define RKC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
    496 	ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
    497 #define KBx(i)  \
    498   (k + (GETARG_Bx(i) != 0 ? GETARG_Bx(i) - 1 : GETARG_Ax(*ci->u.l.savedpc++)))
    499 
    500 
    501 /* execute a jump instruction */
    502 #define dojump(ci,i,e) \
    503   { int a = GETARG_A(i); \
    504     if (a > 0) luaF_close(L, ci->u.l.base + a - 1); \
    505     ci->u.l.savedpc += GETARG_sBx(i) + e; }
    506 
    507 /* for test instructions, execute the jump instruction that follows it */
    508 #define donextjump(ci)	{ i = *ci->u.l.savedpc; dojump(ci, i, 1); }
    509 
    510 
    511 #define Protect(x)	{ {x;}; base = ci->u.l.base; }
    512 
    513 #define checkGC(L,c)  \
    514   Protect( luaC_condGC(L,{L->top = (c);  /* limit of live values */ \
    515                           luaC_step(L); \
    516                           L->top = ci->top;})  /* restore top */ \
    517            luai_threadyield(L); )
    518 
    519 
    520 #define arith_op(op,tm) { \
    521         TValue *rb = RKB(i); \
    522         TValue *rc = RKC(i); \
    523         if (ttisnumber(rb) && ttisnumber(rc)) { \
    524           lua_Number nb = nvalue(rb), nc = nvalue(rc); \
    525           setnvalue(ra, op(L, nb, nc)); \
    526         } \
    527         else { Protect(luaV_arith(L, ra, rb, rc, tm)); } }
    528 
    529 
    530 #define vmdispatch(o)	switch(o)
    531 #define vmcase(l,b)	case l: {b}  break;
    532 #define vmcasenb(l,b)	case l: {b}		/* nb = no break */
    533 
    534 void luaV_execute (lua_State *L) {
    535   CallInfo *ci = L->ci;
    536   LClosure *cl;
    537   TValue *k;
    538   StkId base;
    539  newframe:  /* reentry point when frame changes (call/return) */
    540   lua_assert(ci == L->ci);
    541   cl = clLvalue(ci->func);
    542   k = cl->p->k;
    543   base = ci->u.l.base;
    544   /* main loop of interpreter */
    545   for (;;) {
    546     Instruction i = *(ci->u.l.savedpc++);
    547     StkId ra;
    548     if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&
    549         (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {
    550       Protect(traceexec(L));
    551     }
    552     /* WARNING: several calls may realloc the stack and invalidate `ra' */
    553     ra = RA(i);
    554     lua_assert(base == ci->u.l.base);
    555     lua_assert(base <= L->top && L->top < L->stack + L->stacksize);
    556     vmdispatch (GET_OPCODE(i)) {
    557       vmcase(OP_MOVE,
    558         setobjs2s(L, ra, RB(i));
    559       )
    560       vmcase(OP_LOADK,
    561         TValue *rb = k + GETARG_Bx(i);
    562         setobj2s(L, ra, rb);
    563       )
    564       vmcase(OP_LOADKX,
    565         TValue *rb;
    566         lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
    567         rb = k + GETARG_Ax(*ci->u.l.savedpc++);
    568         setobj2s(L, ra, rb);
    569       )
    570       vmcase(OP_LOADBOOL,
    571         setbvalue(ra, GETARG_B(i));
    572         if (GETARG_C(i)) ci->u.l.savedpc++;  /* skip next instruction (if C) */
    573       )
    574       vmcase(OP_LOADNIL,
    575         int b = GETARG_B(i);
    576         do {
    577           setnilvalue(ra++);
    578         } while (b--);
    579       )
    580       vmcase(OP_GETUPVAL,
    581         int b = GETARG_B(i);
    582         setobj2s(L, ra, cl->upvals[b]->v);
    583       )
    584       vmcase(OP_GETTABUP,
    585         int b = GETARG_B(i);
    586         Protect(luaV_gettable(L, cl->upvals[b]->v, RKC(i), ra));
    587       )
    588       vmcase(OP_GETTABLE,
    589         Protect(luaV_gettable(L, RB(i), RKC(i), ra));
    590       )
    591       vmcase(OP_SETTABUP,
    592         int a = GETARG_A(i);
    593         Protect(luaV_settable(L, cl->upvals[a]->v, RKB(i), RKC(i)));
    594       )
    595       vmcase(OP_SETUPVAL,
    596         UpVal *uv = cl->upvals[GETARG_B(i)];
    597         setobj(L, uv->v, ra);
    598         luaC_barrier(L, uv, ra);
    599       )
    600       vmcase(OP_SETTABLE,
    601         Protect(luaV_settable(L, ra, RKB(i), RKC(i)));
    602       )
    603       vmcase(OP_NEWTABLE,
    604         int b = GETARG_B(i);
    605         int c = GETARG_C(i);
    606         Table *t = luaH_new(L);
    607         sethvalue(L, ra, t);
    608         if (b != 0 || c != 0)
    609           luaH_resize(L, t, luaO_fb2int(b), luaO_fb2int(c));
    610         checkGC(L, ra + 1);
    611       )
    612       vmcase(OP_SELF,
    613         StkId rb = RB(i);
    614         setobjs2s(L, ra+1, rb);
    615         Protect(luaV_gettable(L, rb, RKC(i), ra));
    616       )
    617       vmcase(OP_ADD,
    618         arith_op(luai_numadd, TM_ADD);
    619       )
    620       vmcase(OP_SUB,
    621         arith_op(luai_numsub, TM_SUB);
    622       )
    623       vmcase(OP_MUL,
    624         arith_op(luai_nummul, TM_MUL);
    625       )
    626       vmcase(OP_DIV,
    627         arith_op(luai_numdiv, TM_DIV);
    628       )
    629       vmcase(OP_MOD,
    630         arith_op(luai_nummod, TM_MOD);
    631       )
    632       vmcase(OP_POW,
    633         arith_op(luai_numpow, TM_POW);
    634       )
    635       vmcase(OP_UNM,
    636         TValue *rb = RB(i);
    637         if (ttisnumber(rb)) {
    638           lua_Number nb = nvalue(rb);
    639           setnvalue(ra, luai_numunm(L, nb));
    640         }
    641         else {
    642           Protect(luaV_arith(L, ra, rb, rb, TM_UNM));
    643         }
    644       )
    645       vmcase(OP_NOT,
    646         TValue *rb = RB(i);
    647         int res = l_isfalse(rb);  /* next assignment may change this value */
    648         setbvalue(ra, res);
    649       )
    650       vmcase(OP_LEN,
    651         Protect(luaV_objlen(L, ra, RB(i)));
    652       )
    653       vmcase(OP_CONCAT,
    654         int b = GETARG_B(i);
    655         int c = GETARG_C(i);
    656         StkId rb;
    657         L->top = base + c + 1;  /* mark the end of concat operands */
    658         Protect(luaV_concat(L, c - b + 1));
    659         ra = RA(i);  /* 'luav_concat' may invoke TMs and move the stack */
    660         rb = b + base;
    661         setobjs2s(L, ra, rb);
    662         checkGC(L, (ra >= rb ? ra + 1 : rb));
    663         L->top = ci->top;  /* restore top */
    664       )
    665       vmcase(OP_JMP,
    666         dojump(ci, i, 0);
    667       )
    668       vmcase(OP_EQ,
    669         TValue *rb = RKB(i);
    670         TValue *rc = RKC(i);
    671         Protect(
    672           if (cast_int(equalobj(L, rb, rc)) != GETARG_A(i))
    673             ci->u.l.savedpc++;
    674           else
    675             donextjump(ci);
    676         )
    677       )
    678       vmcase(OP_LT,
    679         Protect(
    680           if (luaV_lessthan(L, RKB(i), RKC(i)) != GETARG_A(i))
    681             ci->u.l.savedpc++;
    682           else
    683             donextjump(ci);
    684         )
    685       )
    686       vmcase(OP_LE,
    687         Protect(
    688           if (luaV_lessequal(L, RKB(i), RKC(i)) != GETARG_A(i))
    689             ci->u.l.savedpc++;
    690           else
    691             donextjump(ci);
    692         )
    693       )
    694       vmcase(OP_TEST,
    695         if (GETARG_C(i) ? l_isfalse(ra) : !l_isfalse(ra))
    696             ci->u.l.savedpc++;
    697           else
    698           donextjump(ci);
    699       )
    700       vmcase(OP_TESTSET,
    701         TValue *rb = RB(i);
    702         if (GETARG_C(i) ? l_isfalse(rb) : !l_isfalse(rb))
    703           ci->u.l.savedpc++;
    704         else {
    705           setobjs2s(L, ra, rb);
    706           donextjump(ci);
    707         }
    708       )
    709       vmcase(OP_CALL,
    710         int b = GETARG_B(i);
    711         int nresults = GETARG_C(i) - 1;
    712         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
    713         if (luaD_precall(L, ra, nresults)) {  /* C function? */
    714           if (nresults >= 0) L->top = ci->top;  /* adjust results */
    715           base = ci->u.l.base;
    716         }
    717         else {  /* Lua function */
    718           ci = L->ci;
    719           ci->callstatus |= CIST_REENTRY;
    720           goto newframe;  /* restart luaV_execute over new Lua function */
    721         }
    722       )
    723       vmcase(OP_TAILCALL,
    724         int b = GETARG_B(i);
    725         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
    726         lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
    727         if (luaD_precall(L, ra, LUA_MULTRET))  /* C function? */
    728           base = ci->u.l.base;
    729         else {
    730           /* tail call: put called frame (n) in place of caller one (o) */
    731           CallInfo *nci = L->ci;  /* called frame */
    732           CallInfo *oci = nci->previous;  /* caller frame */
    733           StkId nfunc = nci->func;  /* called function */
    734           StkId ofunc = oci->func;  /* caller function */
    735           /* last stack slot filled by 'precall' */
    736           StkId lim = nci->u.l.base + getproto(nfunc)->numparams;
    737           int aux;
    738           /* close all upvalues from previous call */
    739           if (cl->p->sizep > 0) luaF_close(L, oci->u.l.base);
    740           /* move new frame into old one */
    741           for (aux = 0; nfunc + aux < lim; aux++)
    742             setobjs2s(L, ofunc + aux, nfunc + aux);
    743           oci->u.l.base = ofunc + (nci->u.l.base - nfunc);  /* correct base */
    744           oci->top = L->top = ofunc + (L->top - nfunc);  /* correct top */
    745           oci->u.l.savedpc = nci->u.l.savedpc;
    746           oci->callstatus |= CIST_TAIL;  /* function was tail called */
    747           ci = L->ci = oci;  /* remove new frame */
    748           lua_assert(L->top == oci->u.l.base + getproto(ofunc)->maxstacksize);
    749           goto newframe;  /* restart luaV_execute over new Lua function */
    750         }
    751       )
    752       vmcasenb(OP_RETURN,
    753         int b = GETARG_B(i);
    754         if (b != 0) L->top = ra+b-1;
    755         if (cl->p->sizep > 0) luaF_close(L, base);
    756         b = luaD_poscall(L, ra);
    757         if (!(ci->callstatus & CIST_REENTRY))  /* 'ci' still the called one */
    758           return;  /* external invocation: return */
    759         else {  /* invocation via reentry: continue execution */
    760           ci = L->ci;
    761           if (b) L->top = ci->top;
    762           lua_assert(isLua(ci));
    763           lua_assert(GET_OPCODE(*((ci)->u.l.savedpc - 1)) == OP_CALL);
    764           goto newframe;  /* restart luaV_execute over new Lua function */
    765         }
    766       )
    767       vmcase(OP_FORLOOP,
    768         lua_Number step = nvalue(ra+2);
    769         lua_Number idx = luai_numadd(L, nvalue(ra), step); /* increment index */
    770         lua_Number limit = nvalue(ra+1);
    771         if (luai_numlt(L, 0, step) ? luai_numle(L, idx, limit)
    772                                    : luai_numle(L, limit, idx)) {
    773           ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
    774           setnvalue(ra, idx);  /* update internal index... */
    775           setnvalue(ra+3, idx);  /* ...and external index */
    776         }
    777       )
    778       vmcase(OP_FORPREP,
    779         const TValue *init = ra;
    780         const TValue *plimit = ra+1;
    781         const TValue *pstep = ra+2;
    782         if (!tonumber(init, ra))
    783           luaG_runerror(L, LUA_QL("for") " initial value must be a number");
    784         else if (!tonumber(plimit, ra+1))
    785           luaG_runerror(L, LUA_QL("for") " limit must be a number");
    786         else if (!tonumber(pstep, ra+2))
    787           luaG_runerror(L, LUA_QL("for") " step must be a number");
    788         setnvalue(ra, luai_numsub(L, nvalue(ra), nvalue(pstep)));
    789         ci->u.l.savedpc += GETARG_sBx(i);
    790       )
    791       vmcasenb(OP_TFORCALL,
    792         StkId cb = ra + 3;  /* call base */
    793         setobjs2s(L, cb+2, ra+2);
    794         setobjs2s(L, cb+1, ra+1);
    795         setobjs2s(L, cb, ra);
    796         L->top = cb + 3;  /* func. + 2 args (state and index) */
    797         Protect(luaD_call(L, cb, GETARG_C(i), 1));
    798         L->top = ci->top;
    799         i = *(ci->u.l.savedpc++);  /* go to next instruction */
    800         ra = RA(i);
    801         lua_assert(GET_OPCODE(i) == OP_TFORLOOP);
    802         goto l_tforloop;
    803       )
    804       vmcase(OP_TFORLOOP,
    805         l_tforloop:
    806         if (!ttisnil(ra + 1)) {  /* continue loop? */
    807           setobjs2s(L, ra, ra + 1);  /* save control variable */
    808            ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
    809         }
    810       )
    811       vmcase(OP_SETLIST,
    812         int n = GETARG_B(i);
    813         int c = GETARG_C(i);
    814         int last;
    815         Table *h;
    816         if (n == 0) n = cast_int(L->top - ra) - 1;
    817         if (c == 0) {
    818           lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
    819           c = GETARG_Ax(*ci->u.l.savedpc++);
    820         }
    821         luai_runtimecheck(L, ttistable(ra));
    822         h = hvalue(ra);
    823         last = ((c-1)*LFIELDS_PER_FLUSH) + n;
    824         if (last > h->sizearray)  /* needs more space? */
    825           luaH_resizearray(L, h, last);  /* pre-allocate it at once */
    826         for (; n > 0; n--) {
    827           TValue *val = ra+n;
    828           luaH_setint(L, h, last--, val);
    829           luaC_barrierback(L, obj2gco(h), val);
    830         }
    831         L->top = ci->top;  /* correct top (in case of previous open call) */
    832       )
    833       vmcase(OP_CLOSURE,
    834         Proto *p = cl->p->p[GETARG_Bx(i)];
    835         Closure *ncl = getcached(p, cl->upvals, base);  /* cached closure */
    836         if (ncl == NULL)  /* no match? */
    837           pushclosure(L, p, cl->upvals, base, ra);  /* create a new one */
    838         else
    839           setclLvalue(L, ra, ncl);  /* push cashed closure */
    840         checkGC(L, ra + 1);
    841       )
    842       vmcase(OP_VARARG,
    843         int b = GETARG_B(i) - 1;
    844         int j;
    845         int n = cast_int(base - ci->func) - cl->p->numparams - 1;
    846         if (b < 0) {  /* B == 0? */
    847           b = n;  /* get all var. arguments */
    848           Protect(luaD_checkstack(L, n));
    849           ra = RA(i);  /* previous call may change the stack */
    850           L->top = ra + n;
    851         }
    852         for (j = 0; j < b; j++) {
    853           if (j < n) {
    854             setobjs2s(L, ra + j, base - n + j);
    855           }
    856           else {
    857             setnilvalue(ra + j);
    858           }
    859         }
    860       )
    861       vmcase(OP_EXTRAARG,
    862         lua_assert(0);
    863       )
    864     }
    865   }
    866 }
    867 
    868