ldebug.c

MTK上实现虚拟机的一种有效方案

  }
  return 1;
}


static Instruction symbexec (const Proto *pt, int lastpc, int reg) {
  int pc;
  int last;  /* stores position of last instruction that changed `reg' */
  last = pt->sizecode-1;  /* points to final return (a `neutral' instruction) */
  check(precheck(pt));
  for (pc = 0; pc < lastpc; pc++) {
    Instruction i = pt->code[pc];
    OpCode op = GET_OPCODE(i);
    int a = GETARG_A(i);
    int b = 0;
    int c = 0;
    check(op < NUM_OPCODES);
    checkreg(pt, a);
    switch (getOpMode(op)) {
      case iABC: {
        b = GETARG_B(i);
        c = GETARG_C(i);
        check(checkArgMode(pt, b, getBMode(op)));
        check(checkArgMode(pt, c, getCMode(op)));
        break;
      }
      case iABx: {
        b = GETARG_Bx(i);
        if (getBMode(op) == OpArgK) check(b < pt->sizek);
        break;
      }
      case iAsBx: {
        b = GETARG_sBx(i);
        if (getBMode(op) == OpArgR) {
          int dest = pc+1+b;
          check(0 <= dest && dest < pt->sizecode);
          if (dest > 0) {
            /* cannot jump to a setlist count */
            Instruction d = pt->code[dest-1];
            check(!(GET_OPCODE(d) == OP_SETLIST && GETARG_C(d) == 0));
          }
        }
        break;
      }
    }
    if (testAMode(op)) {
      if (a == reg) last = pc;  /* change register `a' */
    }
    if (testTMode(op)) {
      check(pc+2 < pt->sizecode);  /* check skip */
      check(GET_OPCODE(pt->code[pc+1]) == OP_JMP);
    }
    switch (op) {
      case OP_LOADBOOL: {
        check(c == 0 || pc+2 < pt->sizecode);  /* check its jump */
        break;
      }
      case OP_LOADNIL: {
        if (a <= reg && reg <= b)
          last = pc;  /* set registers from `a' to `b' */
        break;
      }
      case OP_GETUPVAL:
      case OP_SETUPVAL: {
        check(b < pt->nups);
        break;
      }
      case OP_GETGLOBAL:
      case OP_SETGLOBAL: {
        check(ttisstring(&pt->k[b]));
        break;
      }
      case OP_SELF: {
        checkreg(pt, a+1);
        if (reg == a+1) last = pc;
        break;
      }
      case OP_CONCAT: {
        check(b < c);  /* at least two operands */
        break;
      }
      case OP_TFORLOOP: {
        check(c >= 1);  /* at least one result (control variable) */
        checkreg(pt, a+2+c);  /* space for results */
        if (reg >= a+2) last = pc;  /* affect all regs above its base */
        break;
      }
      case OP_FORLOOP:
      case OP_FORPREP:
        checkreg(pt, a+3);
        /* go through */
      case OP_JMP: {
        int dest = pc+1+b;
        /* not full check and jump is forward and do not skip `lastpc'? */
        if (reg != NO_REG && pc < dest && dest <= lastpc)
          pc += b;  /* do the jump */
        break;
      }
      case OP_CALL:
      case OP_TAILCALL: {
        if (b != 0) {
          checkreg(pt, a+b-1);
        }
        c--;  /* c = num. returns */
        if (c == LUA_MULTRET) {
          check(checkopenop(pt, pc));
        }
        else if (c != 0)
          checkreg(pt, a+c-1);
        if (reg >= a) last = pc;  /* affect all registers above base */
        break;
      }
      case OP_RETURN: {
        b--;  /* b = num. returns */
        if (b > 0) checkreg(pt, a+b-1);
        break;
      }
      case OP_SETLIST: {
        if (b > 0) checkreg(pt, a + b);
        if (c == 0) pc++;
        break;
      }
      case OP_CLOSURE: {
        int nup;
        check(b < pt->sizep);
        nup = pt->p[b]->nups;
        check(pc + nup < pt->sizecode);
        for (; nup>0; nup--) {
          OpCode op1 = GET_OPCODE(pt->code[pc+nup]);
          check(op1 == OP_GETUPVAL || op1 == OP_MOVE);
        }
        break;
      }
      case OP_VARARG: {
        check((pt->is_vararg & VARARG_ISVARARG) &&
             !(pt->is_vararg & VARARG_NEEDSARG));
        b--;
        if (b == LUA_MULTRET) check(checkopenop(pt, pc));
        checkreg(pt, a+b-1);
        break;
      }
      default: break;
    }
  }
  return pt->code[last];
}

#undef check
#undef checkjump
#undef checkreg

/* }====================================================== */


int luaG_checkcode (const Proto *pt) {
  return (symbexec(pt, pt->sizecode, NO_REG) != 0);
}


static const char *kname (Proto *p, int c) {
  if (ISK(c) && ttisstring(&p->k[INDEXK(c)]))
    return svalue(&p->k[INDEXK(c)]);
  else
    return "?";
}


static const char *getobjname (lua_State *L, CallInfo *ci, int stackpos,
                               const char **name) {
  if (isLua(ci)) {  /* a Lua function? */
    Proto *p = ci_func(ci)->l.p;
    int pc = currentpc(L, ci);
    Instruction i;
    *name = luaF_getlocalname(p, stackpos+1, pc);
    if (*name)  /* is a local? */
      return "local";
    i = symbexec(p, pc, stackpos);  /* try symbolic execution */
    lua_assert(pc != -1);
    switch (GET_OPCODE(i)) {
      case OP_GETGLOBAL: {
        int g = GETARG_Bx(i);  /* global index */
        lua_assert(ttisstring(&p->k[g]));
        *name = svalue(&p->k[g]);
        return "global";
      }
      case OP_MOVE: {
        int a = GETARG_A(i);
        int b = GETARG_B(i);  /* move from `b' to `a' */
        if (b < a)
          return getobjname(L, ci, b, name);  /* get name for `b' */
        break;
      }
      case OP_GETTABLE: {
        int k = GETARG_C(i);  /* key index */
        *name = kname(p, k);
        return "field";
      }
      case OP_GETUPVAL: {
        int u = GETARG_B(i);  /* upvalue index */
        *name = p->upvalues ? getstr(p->upvalues[u]) : "?";
        return "upvalue";
      }
      case OP_SELF: {
        int k = GETARG_C(i);  /* key index */
        *name = kname(p, k);
        return "method";
      }
      default: break;
    }
  }
  return NULL;  /* no useful name found */
}


static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
  Instruction i;
  if ((isLua(ci) && ci->tailcalls > 0) || !isLua(ci - 1))
    return NULL;  /* calling function is not Lua (or is unknown) */
  ci--;  /* calling function */
  i = ci_func(ci)->l.p->code[currentpc(L, ci)];
  if (GET_OPCODE(i) == OP_CALL || GET_OPCODE(i) == OP_TAILCALL ||
      GET_OPCODE(i) == OP_TFORLOOP)
    return getobjname(L, ci, GETARG_A(i), name);
  else
    return NULL;  /* no useful name can be found */
}


/* only ANSI way to check whether a pointer points to an array */
static int isinstack (CallInfo *ci, const TValue *o) {
  StkId p;
  for (p = ci->base; p < ci->top; p++)
    if (o == p) return 1;
  return 0;
}


void luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
  const char *name = NULL;
  const char *t = luaT_typenames[ttype(o)];
  const char *kind = (isinstack(L->ci, o)) ?
                         getobjname(L, L->ci, cast_int(o - L->base), &name) :
                         NULL;
  if (kind)
    luaG_runerror(L, "attempt to %s %s " LUA_QS " (a %s value)",
                op, kind, name, t);
  else
    luaG_runerror(L, "attempt to %s a %s value", op, t);
}


void luaG_concaterror (lua_State *L, StkId p1, StkId p2) {
  if (ttisstring(p1)) p1 = p2;
  lua_assert(!ttisstring(p1));
  luaG_typeerror(L, p1, "concatenate");
}


void luaG_aritherror (lua_State *L, const TValue *p1, const TValue *p2) {
  TValue temp;
  if (luaV_tonumber(p1, &temp) == NULL)
    p2 = p1;  /* first operand is wrong */
  luaG_typeerror(L, p2, "perform arithmetic on");
}


int luaG_ordererror (lua_State *L, const TValue *p1, const TValue *p2) {
  const char *t1 = luaT_typenames[ttype(p1)];
  const char *t2 = luaT_typenames[ttype(p2)];
  if (t1[2] == t2[2])
    luaG_runerror(L, "attempt to compare two %s values", t1);
  else
    luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
  return 0;
}


static void addinfo (lua_State *L, const char *msg) {
  CallInfo *ci = L->ci;
  if (isLua(ci)) {  /* is Lua code? */
    char buff[LUA_IDSIZE];  /* add file:line information */
    int line = currentline(L, ci);
    luaO_chunkid(buff, getstr(getluaproto(ci)->source), LUA_IDSIZE);
    luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
  }
}


void luaG_errormsg (lua_State *L) {
  if (L->errfunc != 0) {  /* is there an error handling function? */
    StkId errfunc = restorestack(L, L->errfunc);
    if (!ttisfunction(errfunc)) luaD_throw(L, LUA_ERRERR);
    setobjs2s(L, L->top, L->top - 1);  /* move argument */
    setobjs2s(L, L->top - 1, errfunc);  /* push function */
    incr_top(L);
    luaD_call(L, L->top - 2, 1);  /* call it */
  }
  luaD_throw(L, LUA_ERRRUN);
}


void luaG_runerror (lua_State *L, const char *fmt, ...) {
  va_list argp;
  va_start(argp, fmt);
  addinfo(L, luaO_pushvfstring(L, fmt, argp));
  va_end(argp);
  luaG_errormsg(L);
}