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  1. /*
  2. ** $Id: lvm.c,v 2.155.1.1 2013/04/12 18:48:47 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.