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#define lvm_c
9#define LUA_CORE
10
11#include <sys/lua/lua.h>
12
13#include "ldebug.h"
14#include "ldo.h"
15#include "lfunc.h"
16#include "lgc.h"
17#include "lobject.h"
18#include "lopcodes.h"
19#include "lstate.h"
20#include "lstring.h"
21#include "ltable.h"
22#include "ltm.h"
23#include "lvm.h"
24
25#ifdef _KERNEL
26#define	strcoll(l,r) (strcmp((l),(r)))
27#endif
28
29/* limit for table tag-method chains (to avoid loops) */
30#define MAXTAGLOOP	100
31
32
33const TValue *luaV_tonumber (const TValue *obj, TValue *n) {
34  lua_Number num;
35  if (ttisnumber(obj)) return obj;
36  if (ttisstring(obj) && luaO_str2d(svalue(obj), tsvalue(obj)->len, &num)) {
37    setnvalue(n, num);
38    return n;
39  }
40  else
41    return NULL;
42}
43
44
45int luaV_tostring (lua_State *L, StkId obj) {
46  if (!ttisnumber(obj))
47    return 0;
48  else {
49    char s[LUAI_MAXNUMBER2STR];
50    lua_Number n = nvalue(obj);
51    int l = lua_number2str(s, n);
52    setsvalue2s(L, obj, luaS_newlstr(L, s, l));
53    return 1;
54  }
55}
56
57
58static void traceexec (lua_State *L) {
59  CallInfo *ci = L->ci;
60  lu_byte mask = L->hookmask;
61  int counthook = ((mask & LUA_MASKCOUNT) && L->hookcount == 0);
62  if (counthook)
63    resethookcount(L);  /* reset count */
64  if (ci->callstatus & CIST_HOOKYIELD) {  /* called hook last time? */
65    ci->callstatus &= ~CIST_HOOKYIELD;  /* erase mark */
66    return;  /* do not call hook again (VM yielded, so it did not move) */
67  }
68  if (counthook)
69    luaD_hook(L, LUA_HOOKCOUNT, -1);  /* call count hook */
70  if (mask & LUA_MASKLINE) {
71    Proto *p = ci_func(ci)->p;
72    int npc = pcRel(ci->u.l.savedpc, p);
73    int newline = getfuncline(p, npc);
74    if (npc == 0 ||  /* call linehook when enter a new function, */
75        ci->u.l.savedpc <= L->oldpc ||  /* when jump back (loop), or when */
76        newline != getfuncline(p, pcRel(L->oldpc, p)))  /* enter a new line */
77      luaD_hook(L, LUA_HOOKLINE, newline);  /* call line hook */
78  }
79  L->oldpc = ci->u.l.savedpc;
80  if (L->status == LUA_YIELD) {  /* did hook yield? */
81    if (counthook)
82      L->hookcount = 1;  /* undo decrement to zero */
83    ci->u.l.savedpc--;  /* undo increment (resume will increment it again) */
84    ci->callstatus |= CIST_HOOKYIELD;  /* mark that it yielded */
85    ci->func = L->top - 1;  /* protect stack below results */
86    luaD_throw(L, LUA_YIELD);
87  }
88}
89
90
91static void callTM (lua_State *L, const TValue *f, const TValue *p1,
92                    const TValue *p2, TValue *p3, int hasres) {
93  if (L == NULL) return;
94
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
110void 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
136void 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
175static 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
186static 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
200static 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
209static 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
231int 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
243int 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*/
260int 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 || L == 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
293void 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
335void 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 * luaV_div and luaV_mod patched in from Lua 5.3.2 in order to properly handle
361 * div/mod by zero (instead of crashing, which is the default behavior in
362 * Lua 5.2)
363 */
364
365/*
366** Integer division; return 'm // n', that is, floor(m/n).
367** C division truncates its result (rounds towards zero).
368** 'floor(q) == trunc(q)' when 'q >= 0' or when 'q' is integer,
369** otherwise 'floor(q) == trunc(q) - 1'.
370*/
371static lua_Number luaV_div (lua_State *L, lua_Number m, lua_Number n) {
372  if ((lua_Unsigned)(n) + 1u <= 1u) {  /* special cases: -1 or 0 */
373    if (n == 0)
374      luaG_runerror(L, "attempt to divide by zero");
375    return (0 - m);   /* n==-1; avoid overflow with 0x80000...//-1 */
376  }
377  else {
378    lua_Number q = m / n;  /* perform C division */
379    if ((m ^ n) < 0 && m % n != 0)  /* 'm/n' would be negative non-integer? */
380      q -= 1;  /* correct result for different rounding */
381    return q;
382  }
383}
384
385
386/*
387** Integer modulus; return 'm % n'. (Assume that C '%' with
388** negative operands follows C99 behavior. See previous comment
389** about luaV_div.)
390*/
391static lua_Number luaV_mod (lua_State *L, lua_Number m, lua_Number n) {
392  if ((lua_Unsigned)(n) + 1u <= 1u) {  /* special cases: -1 or 0 */
393    if (n == 0)
394      luaG_runerror(L, "attempt to perform 'n%%0'");
395    return 0;   /* m % -1 == 0; avoid overflow with 0x80000...%-1 */
396  }
397  else {
398    lua_Number r = m % n;
399    if (r != 0 && (m ^ n) < 0)  /* 'm/n' would be non-integer negative? */
400      r += n;  /* correct result for different rounding */
401    return r;
402  }
403}
404
405/*
406 * End patch from 5.3.2
407 */
408
409void luaV_arith (lua_State *L, StkId ra, const TValue *rb,
410                 const TValue *rc, TMS op) {
411  TValue tempb, tempc;
412  const TValue *b, *c;
413  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
414      (c = luaV_tonumber(rc, &tempc)) != NULL) {
415    /*
416     * Patched: if dividing or modding, use patched functions from 5.3
417     */
418    lua_Number res;
419    int lop = op - TM_ADD + LUA_OPADD;
420    if (lop == LUA_OPDIV) {
421      res = luaV_div(L, nvalue(b), nvalue(c));
422    } else if (lop == LUA_OPMOD) {
423      res = luaV_mod(L, nvalue(b), nvalue(c));
424    } else {
425      res = luaO_arith(op - TM_ADD + LUA_OPADD, nvalue(b), nvalue(c));
426    }
427    setnvalue(ra, res);
428  }
429  else if (!call_binTM(L, rb, rc, ra, op))
430    luaG_aritherror(L, rb, rc);
431}
432
433
434/*
435** check whether cached closure in prototype 'p' may be reused, that is,
436** whether there is a cached closure with the same upvalues needed by
437** new closure to be created.
438*/
439static Closure *getcached (Proto *p, UpVal **encup, StkId base) {
440  Closure *c = p->cache;
441  if (c != NULL) {  /* is there a cached closure? */
442    int nup = p->sizeupvalues;
443    Upvaldesc *uv = p->upvalues;
444    int i;
445    for (i = 0; i < nup; i++) {  /* check whether it has right upvalues */
446      TValue *v = uv[i].instack ? base + uv[i].idx : encup[uv[i].idx]->v;
447      if (c->l.upvals[i]->v != v)
448        return NULL;  /* wrong upvalue; cannot reuse closure */
449    }
450  }
451  return c;  /* return cached closure (or NULL if no cached closure) */
452}
453
454
455/*
456** create a new Lua closure, push it in the stack, and initialize
457** its upvalues. Note that the call to 'luaC_barrierproto' must come
458** before the assignment to 'p->cache', as the function needs the
459** original value of that field.
460*/
461static void pushclosure (lua_State *L, Proto *p, UpVal **encup, StkId base,
462                         StkId ra) {
463  int nup = p->sizeupvalues;
464  Upvaldesc *uv = p->upvalues;
465  int i;
466  Closure *ncl = luaF_newLclosure(L, nup);
467  ncl->l.p = p;
468  setclLvalue(L, ra, ncl);  /* anchor new closure in stack */
469  for (i = 0; i < nup; i++) {  /* fill in its upvalues */
470    if (uv[i].instack)  /* upvalue refers to local variable? */
471      ncl->l.upvals[i] = luaF_findupval(L, base + uv[i].idx);
472    else  /* get upvalue from enclosing function */
473      ncl->l.upvals[i] = encup[uv[i].idx];
474  }
475  luaC_barrierproto(L, p, ncl);
476  p->cache = ncl;  /* save it on cache for reuse */
477}
478
479
480/*
481** finish execution of an opcode interrupted by an yield
482*/
483void luaV_finishOp (lua_State *L) {
484  CallInfo *ci = L->ci;
485  StkId base = ci->u.l.base;
486  Instruction inst = *(ci->u.l.savedpc - 1);  /* interrupted instruction */
487  OpCode op = GET_OPCODE(inst);
488  switch (op) {  /* finish its execution */
489    case OP_ADD: case OP_SUB: case OP_MUL: case OP_DIV:
490    case OP_MOD: case OP_POW: case OP_UNM: case OP_LEN:
491    case OP_GETTABUP: case OP_GETTABLE: case OP_SELF: {
492      setobjs2s(L, base + GETARG_A(inst), --L->top);
493      break;
494    }
495    case OP_LE: case OP_LT: case OP_EQ: {
496      int res = !l_isfalse(L->top - 1);
497      L->top--;
498      /* metamethod should not be called when operand is K */
499      lua_assert(!ISK(GETARG_B(inst)));
500      if (op == OP_LE &&  /* "<=" using "<" instead? */
501          ttisnil(luaT_gettmbyobj(L, base + GETARG_B(inst), TM_LE)))
502        res = !res;  /* invert result */
503      lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_JMP);
504      if (res != GETARG_A(inst))  /* condition failed? */
505        ci->u.l.savedpc++;  /* skip jump instruction */
506      break;
507    }
508    case OP_CONCAT: {
509      StkId top = L->top - 1;  /* top when 'call_binTM' was called */
510      int b = GETARG_B(inst);      /* first element to concatenate */
511      int total = cast_int(top - 1 - (base + b));  /* yet to concatenate */
512      setobj2s(L, top - 2, top);  /* put TM result in proper position */
513      if (total > 1) {  /* are there elements to concat? */
514        L->top = top - 1;  /* top is one after last element (at top-2) */
515        luaV_concat(L, total);  /* concat them (may yield again) */
516      }
517      /* move final result to final position */
518      setobj2s(L, ci->u.l.base + GETARG_A(inst), L->top - 1);
519      L->top = ci->top;  /* restore top */
520      break;
521    }
522    case OP_TFORCALL: {
523      lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_TFORLOOP);
524      L->top = ci->top;  /* correct top */
525      break;
526    }
527    case OP_CALL: {
528      if (GETARG_C(inst) - 1 >= 0)  /* nresults >= 0? */
529        L->top = ci->top;  /* adjust results */
530      break;
531    }
532    case OP_TAILCALL: case OP_SETTABUP: case OP_SETTABLE:
533      break;
534    default: lua_assert(0);
535  }
536}
537
538
539
540/*
541** some macros for common tasks in `luaV_execute'
542*/
543
544#if !defined luai_runtimecheck
545#define luai_runtimecheck(L, c)		/* void */
546#endif
547
548
549#define RA(i)	(base+GETARG_A(i))
550/* to be used after possible stack reallocation */
551#define RB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))
552#define RC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))
553#define RKB(i)	check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \
554	ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))
555#define RKC(i)	check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \
556	ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))
557#define KBx(i)  \
558  (k + (GETARG_Bx(i) != 0 ? GETARG_Bx(i) - 1 : GETARG_Ax(*ci->u.l.savedpc++)))
559
560
561/* execute a jump instruction */
562#define dojump(ci,i,e) \
563  { int a = GETARG_A(i); \
564    if (a > 0) luaF_close(L, ci->u.l.base + a - 1); \
565    ci->u.l.savedpc += GETARG_sBx(i) + e; }
566
567/* for test instructions, execute the jump instruction that follows it */
568#define donextjump(ci)	{ i = *ci->u.l.savedpc; dojump(ci, i, 1); }
569
570
571#define Protect(x)	{ {x;} base = ci->u.l.base; }
572
573#define checkGC(L,c)  \
574  Protect( luaC_condGC(L,{L->top = (c);  /* limit of live values */ \
575                          luaC_step(L); \
576                          L->top = ci->top;})  /* restore top */ \
577           luai_threadyield(L); )
578
579
580#define arith_op(op,tm) { \
581        TValue *rb = RKB(i); \
582        TValue *rc = RKC(i); \
583        if (ttisnumber(rb) && ttisnumber(rc)) { \
584          lua_Number nb = nvalue(rb), nc = nvalue(rc); \
585          setnvalue(ra, op(L, nb, nc)); \
586        } \
587        else { Protect(luaV_arith(L, ra, rb, rc, tm)); } }
588
589
590#define vmdispatch(o)	switch(o)
591#define vmcase(l,b)	case l: {b}  break;
592#define vmcasenb(l,b)	case l: {b}		/* nb = no break */
593
594void luaV_execute (lua_State *L) {
595  CallInfo *ci = L->ci;
596  LClosure *cl;
597  TValue *k;
598  StkId base;
599 newframe:  /* reentry point when frame changes (call/return) */
600  lua_assert(ci == L->ci);
601  cl = clLvalue(ci->func);
602  k = cl->p->k;
603  base = ci->u.l.base;
604  /* main loop of interpreter */
605  for (;;) {
606    Instruction i = *(ci->u.l.savedpc++);
607    StkId ra;
608    if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&
609        (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {
610      Protect(traceexec(L));
611    }
612    /* WARNING: several calls may realloc the stack and invalidate `ra' */
613    ra = RA(i);
614    lua_assert(base == ci->u.l.base);
615    lua_assert(base <= L->top && L->top < L->stack + L->stacksize);
616    vmdispatch (GET_OPCODE(i)) {
617      vmcase(OP_MOVE,
618        setobjs2s(L, ra, RB(i));
619      )
620      vmcase(OP_LOADK,
621        TValue *rb = k + GETARG_Bx(i);
622        setobj2s(L, ra, rb);
623      )
624      vmcase(OP_LOADKX,
625        TValue *rb;
626        lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
627        rb = k + GETARG_Ax(*ci->u.l.savedpc++);
628        setobj2s(L, ra, rb);
629      )
630      vmcase(OP_LOADBOOL,
631        setbvalue(ra, GETARG_B(i));
632        if (GETARG_C(i)) ci->u.l.savedpc++;  /* skip next instruction (if C) */
633      )
634      vmcase(OP_LOADNIL,
635        int b = GETARG_B(i);
636        do {
637          setnilvalue(ra++);
638        } while (b--);
639      )
640      vmcase(OP_GETUPVAL,
641        int b = GETARG_B(i);
642        setobj2s(L, ra, cl->upvals[b]->v);
643      )
644      vmcase(OP_GETTABUP,
645        int b = GETARG_B(i);
646        Protect(luaV_gettable(L, cl->upvals[b]->v, RKC(i), ra));
647      )
648      vmcase(OP_GETTABLE,
649        Protect(luaV_gettable(L, RB(i), RKC(i), ra));
650      )
651      vmcase(OP_SETTABUP,
652        int a = GETARG_A(i);
653        Protect(luaV_settable(L, cl->upvals[a]->v, RKB(i), RKC(i)));
654      )
655      vmcase(OP_SETUPVAL,
656        UpVal *uv = cl->upvals[GETARG_B(i)];
657        setobj(L, uv->v, ra);
658        luaC_barrier(L, uv, ra);
659      )
660      vmcase(OP_SETTABLE,
661        Protect(luaV_settable(L, ra, RKB(i), RKC(i)));
662      )
663      vmcase(OP_NEWTABLE,
664        int b = GETARG_B(i);
665        int c = GETARG_C(i);
666        Table *t = luaH_new(L);
667        sethvalue(L, ra, t);
668        if (b != 0 || c != 0)
669          luaH_resize(L, t, luaO_fb2int(b), luaO_fb2int(c));
670        checkGC(L, ra + 1);
671      )
672      vmcase(OP_SELF,
673        StkId rb = RB(i);
674        setobjs2s(L, ra+1, rb);
675        Protect(luaV_gettable(L, rb, RKC(i), ra));
676      )
677      vmcase(OP_ADD,
678        arith_op(luai_numadd, TM_ADD);
679      )
680      vmcase(OP_SUB,
681        arith_op(luai_numsub, TM_SUB);
682      )
683      vmcase(OP_MUL,
684        arith_op(luai_nummul, TM_MUL);
685      )
686      /*
687       * Patched: use luaV_* instead of luai_* to handle div/mod by 0
688       */
689      vmcase(OP_DIV,
690        arith_op(luaV_div, TM_DIV);
691      )
692      vmcase(OP_MOD,
693        arith_op(luaV_mod, TM_MOD);
694      )
695      vmcase(OP_POW,
696        arith_op(luai_numpow, TM_POW);
697      )
698      vmcase(OP_UNM,
699        TValue *rb = RB(i);
700        if (ttisnumber(rb)) {
701          lua_Number nb = nvalue(rb);
702          setnvalue(ra, luai_numunm(L, nb));
703        }
704        else {
705          Protect(luaV_arith(L, ra, rb, rb, TM_UNM));
706        }
707      )
708      vmcase(OP_NOT,
709        TValue *rb = RB(i);
710        int res = l_isfalse(rb);  /* next assignment may change this value */
711        setbvalue(ra, res);
712      )
713      vmcase(OP_LEN,
714        Protect(luaV_objlen(L, ra, RB(i)));
715      )
716      vmcase(OP_CONCAT,
717        int b = GETARG_B(i);
718        int c = GETARG_C(i);
719        StkId rb;
720        L->top = base + c + 1;  /* mark the end of concat operands */
721        Protect(luaV_concat(L, c - b + 1));
722        ra = RA(i);  /* 'luav_concat' may invoke TMs and move the stack */
723        rb = b + base;
724        setobjs2s(L, ra, rb);
725        checkGC(L, (ra >= rb ? ra + 1 : rb));
726        L->top = ci->top;  /* restore top */
727      )
728      vmcase(OP_JMP,
729        dojump(ci, i, 0);
730      )
731      vmcase(OP_EQ,
732        TValue *rb = RKB(i);
733        TValue *rc = RKC(i);
734        Protect(
735          if (cast_int(equalobj(L, rb, rc)) != GETARG_A(i))
736            ci->u.l.savedpc++;
737          else
738            donextjump(ci);
739        )
740      )
741      vmcase(OP_LT,
742        Protect(
743          if (luaV_lessthan(L, RKB(i), RKC(i)) != GETARG_A(i))
744            ci->u.l.savedpc++;
745          else
746            donextjump(ci);
747        )
748      )
749      vmcase(OP_LE,
750        Protect(
751          if (luaV_lessequal(L, RKB(i), RKC(i)) != GETARG_A(i))
752            ci->u.l.savedpc++;
753          else
754            donextjump(ci);
755        )
756      )
757      vmcase(OP_TEST,
758        if (GETARG_C(i) ? l_isfalse(ra) : !l_isfalse(ra))
759            ci->u.l.savedpc++;
760          else
761          donextjump(ci);
762      )
763      vmcase(OP_TESTSET,
764        TValue *rb = RB(i);
765        if (GETARG_C(i) ? l_isfalse(rb) : !l_isfalse(rb))
766          ci->u.l.savedpc++;
767        else {
768          setobjs2s(L, ra, rb);
769          donextjump(ci);
770        }
771      )
772      vmcase(OP_CALL,
773        int b = GETARG_B(i);
774        int nresults = GETARG_C(i) - 1;
775        if (b != 0) L->top = ra+b;  /* else previous instruction set top */
776        if (luaD_precall(L, ra, nresults)) {  /* C function? */
777          if (nresults >= 0) L->top = ci->top;  /* adjust results */
778          base = ci->u.l.base;
779        }
780        else {  /* Lua function */
781          ci = L->ci;
782          ci->callstatus |= CIST_REENTRY;
783          goto newframe;  /* restart luaV_execute over new Lua function */
784        }
785      )
786      vmcase(OP_TAILCALL,
787        int b = GETARG_B(i);
788        if (b != 0) L->top = ra+b;  /* else previous instruction set top */
789        lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
790        if (luaD_precall(L, ra, LUA_MULTRET))  /* C function? */
791          base = ci->u.l.base;
792        else {
793          /* tail call: put called frame (n) in place of caller one (o) */
794          CallInfo *nci = L->ci;  /* called frame */
795          CallInfo *oci = nci->previous;  /* caller frame */
796          StkId nfunc = nci->func;  /* called function */
797          StkId ofunc = oci->func;  /* caller function */
798          /* last stack slot filled by 'precall' */
799          StkId lim = nci->u.l.base + getproto(nfunc)->numparams;
800          int aux;
801          /* close all upvalues from previous call */
802          if (cl->p->sizep > 0) luaF_close(L, oci->u.l.base);
803          /* move new frame into old one */
804          for (aux = 0; nfunc + aux < lim; aux++)
805            setobjs2s(L, ofunc + aux, nfunc + aux);
806          oci->u.l.base = ofunc + (nci->u.l.base - nfunc);  /* correct base */
807          oci->top = L->top = ofunc + (L->top - nfunc);  /* correct top */
808          oci->u.l.savedpc = nci->u.l.savedpc;
809          oci->callstatus |= CIST_TAIL;  /* function was tail called */
810          ci = L->ci = oci;  /* remove new frame */
811          lua_assert(L->top == oci->u.l.base + getproto(ofunc)->maxstacksize);
812          goto newframe;  /* restart luaV_execute over new Lua function */
813        }
814      )
815      vmcasenb(OP_RETURN,
816        int b = GETARG_B(i);
817        if (b != 0) L->top = ra+b-1;
818        if (cl->p->sizep > 0) luaF_close(L, base);
819        b = luaD_poscall(L, ra);
820        if (!(ci->callstatus & CIST_REENTRY))  /* 'ci' still the called one */
821          return;  /* external invocation: return */
822        else {  /* invocation via reentry: continue execution */
823          ci = L->ci;
824          if (b) L->top = ci->top;
825          lua_assert(isLua(ci));
826          lua_assert(GET_OPCODE(*((ci)->u.l.savedpc - 1)) == OP_CALL);
827          goto newframe;  /* restart luaV_execute over new Lua function */
828        }
829      )
830      vmcase(OP_FORLOOP,
831        lua_Number step = nvalue(ra+2);
832        lua_Number idx = luai_numadd(L, nvalue(ra), step); /* increment index */
833        lua_Number limit = nvalue(ra+1);
834        if (luai_numlt(L, 0, step) ? luai_numle(L, idx, limit)
835                                   : luai_numle(L, limit, idx)) {
836          ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
837          setnvalue(ra, idx);  /* update internal index... */
838          setnvalue(ra+3, idx);  /* ...and external index */
839        }
840      )
841      vmcase(OP_FORPREP,
842        const TValue *init = ra;
843        const TValue *plimit = ra+1;
844        const TValue *pstep = ra+2;
845        if (!tonumber(init, ra))
846          luaG_runerror(L, LUA_QL("for") " initial value must be a number");
847        else if (!tonumber(plimit, ra+1))
848          luaG_runerror(L, LUA_QL("for") " limit must be a number");
849        else if (!tonumber(pstep, ra+2))
850          luaG_runerror(L, LUA_QL("for") " step must be a number");
851        setnvalue(ra, luai_numsub(L, nvalue(ra), nvalue(pstep)));
852        ci->u.l.savedpc += GETARG_sBx(i);
853      )
854      vmcasenb(OP_TFORCALL,
855        StkId cb = ra + 3;  /* call base */
856        setobjs2s(L, cb+2, ra+2);
857        setobjs2s(L, cb+1, ra+1);
858        setobjs2s(L, cb, ra);
859        L->top = cb + 3;  /* func. + 2 args (state and index) */
860        Protect(luaD_call(L, cb, GETARG_C(i), 1));
861        L->top = ci->top;
862        i = *(ci->u.l.savedpc++);  /* go to next instruction */
863        ra = RA(i);
864        lua_assert(GET_OPCODE(i) == OP_TFORLOOP);
865        goto l_tforloop;
866      )
867      vmcase(OP_TFORLOOP,
868        l_tforloop:
869        if (!ttisnil(ra + 1)) {  /* continue loop? */
870          setobjs2s(L, ra, ra + 1);  /* save control variable */
871           ci->u.l.savedpc += GETARG_sBx(i);  /* jump back */
872        }
873      )
874      vmcase(OP_SETLIST,
875        int n = GETARG_B(i);
876        int c = GETARG_C(i);
877        int last;
878        Table *h;
879        if (n == 0) n = cast_int(L->top - ra) - 1;
880        if (c == 0) {
881          lua_assert(GET_OPCODE(*ci->u.l.savedpc) == OP_EXTRAARG);
882          c = GETARG_Ax(*ci->u.l.savedpc++);
883        }
884        luai_runtimecheck(L, ttistable(ra));
885        h = hvalue(ra);
886        last = ((c-1)*LFIELDS_PER_FLUSH) + n;
887        if (last > h->sizearray)  /* needs more space? */
888          luaH_resizearray(L, h, last);  /* pre-allocate it at once */
889        for (; n > 0; n--) {
890          TValue *val = ra+n;
891          luaH_setint(L, h, last--, val);
892          luaC_barrierback(L, obj2gco(h), val);
893        }
894        L->top = ci->top;  /* correct top (in case of previous open call) */
895      )
896      vmcase(OP_CLOSURE,
897        Proto *p = cl->p->p[GETARG_Bx(i)];
898        Closure *ncl = getcached(p, cl->upvals, base);  /* cached closure */
899        if (ncl == NULL)  /* no match? */
900          pushclosure(L, p, cl->upvals, base, ra);  /* create a new one */
901        else
902          setclLvalue(L, ra, ncl);  /* push cashed closure */
903        checkGC(L, ra + 1);
904      )
905      vmcase(OP_VARARG,
906        int b = GETARG_B(i) - 1;
907        int j;
908        int n = cast_int(base - ci->func) - cl->p->numparams - 1;
909        if (b < 0) {  /* B == 0? */
910          b = n;  /* get all var. arguments */
911          Protect(luaD_checkstack(L, n));
912          ra = RA(i);  /* previous call may change the stack */
913          L->top = ra + n;
914        }
915        for (j = 0; j < b; j++) {
916          if (j < n) {
917            setobjs2s(L, ra + j, base - n + j);
918          }
919          else {
920            setnilvalue(ra + j);
921          }
922        }
923      )
924      vmcase(OP_EXTRAARG,
925        lua_assert(0);
926      )
927    }
928  }
929}
930