text: /*
  ** $Id: lcode.c,v 2.25.1.3 2007/12/28 15:32:23 roberto Exp $
  ** Code generator for Lua
  ** See Copyright Notice in lua.h
  */
  
  
  #include <stdlib.h>
  
  #define lcode_c
  #define LUA_CORE
  
  #include "lua.h"
  
  #include "lcode.h"
  #include "ldebug.h"
  #include "ldo.h"
  #include "lgc.h"
  #include "llex.h"
  #include "lmem.h"
  #include "lobject.h"
  #include "lopcodes.h"
  #include "lparser.h"
  #include "ltable.h"
  
  
  #define hasjumps(e)	((e)->t != (e)->f)
  
  
  static int isnumeral(expdesc *e) {
    return (e->k == VKNUM && e->t == NO_JUMP && e->f == NO_JUMP);
  }
  
  
  void luaK_nil (FuncState *fs, int from, int n) {
    Instruction *previous;
    if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
      if (fs->pc == 0) {  /* function start? */
        if (from >= fs->nactvar)
          return;  /* positions are already clean */
      }
      else {
        previous = &fs->f->code[fs->pc-1];
        if (GET_OPCODE(*previous) == OP_LOADNIL) {
          int pfrom = GETARG_A(*previous);
          int pto = GETARG_B(*previous);
          if (pfrom <= from && from <= pto+1) {  /* can connect both? */
            if (from+n-1 > pto)
              SETARG_B(*previous, from+n-1);
            return;
          }
        }
      }
    }
    luaK_codeABC(fs, OP_LOADNIL, from, from+n-1, 0);  /* else no optimization */
  }
  
  
  int luaK_jump (FuncState *fs) {
    int jpc = fs->jpc;  /* save list of jumps to here */
    int j;
    fs->jpc = NO_JUMP;
    j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
    luaK_concat(fs, &j, jpc);  /* keep them on hold */
    return j;
  }
  
  
  void luaK_ret (FuncState *fs, int first, int nret) {
    luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
  }
  
  
  static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
    luaK_codeABC(fs, op, A, B, C);
    return luaK_jump(fs);
  }
  
  
  static void fixjump (FuncState *fs, int pc, int dest) {
    Instruction *jmp = &fs->f->code[pc];
    int offset = dest-(pc+1);
    lua_assert(dest != NO_JUMP);
    if (abs(offset) > MAXARG_sBx)
      luaX_syntaxerror(fs->ls, "control structure too long");
    SETARG_sBx(*jmp, offset);
  }
  
  
  /*
  ** returns current `pc' and marks it as a jump target (to avoid wrong
  ** optimizations with consecutive instructions not in the same basic block).
  */
  int luaK_getlabel (FuncState *fs) {
    fs->lasttarget = fs->pc;
    return fs->pc;
  }
  
  
  static int getjump (FuncState *fs, int pc) {
    int offset = GETARG_sBx(fs->f->code[pc]);
    if (offset == NO_JUMP)  /* point to itself represents end of list */
      return NO_JUMP;  /* end of list */
    else
      return (pc+1)+offset;  /* turn offset into absolute position */
  }
  
  
  static Instruction *getjumpcontrol (FuncState *fs, int pc) {
    Instruction *pi = &fs->f->code[pc];
    if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
      return pi-1;
    else
      return pi;
  }
  
  
  /*
  ** check whether list has any jump that do not produce a value
  ** (or produce an inverted value)
  */
  static int need_value (FuncState *fs, int list) {
    for (; list != NO_JUMP; list = getjump(fs, list)) {
      Instruction i = *getjumpcontrol(fs, list);
      if (GET_OPCODE(i) != OP_TESTSET) return 1;
    }
    return 0;  /* not found */
  }
  
  
  static int patchtestreg (FuncState *fs, int node, int reg) {
    Instruction *i = getjumpcontrol(fs, node);
    if (GET_OPCODE(*i) != OP_TESTSET)
      return 0;  /* cannot patch other instructions */
    if (reg != NO_REG && reg != GETARG_B(*i))
      SETARG_A(*i, reg);
    else  /* no register to put value or register already has the value */
      *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
  
    return 1;
  }
  
  
  static void removevalues (FuncState *fs, int list) {
    for (; list != NO_JUMP; list = getjump(fs, list))
        patchtestreg(fs, list, NO_REG);
  }
  
  
  static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
                            int dtarget) {
    while (list != NO_JUMP) {
      int next = getjump(fs, list);
      if (patchtestreg(fs, list, reg))
        fixjump(fs, list, vtarget);
      else
        fixjump(fs, list, dtarget);  /* jump to default target */
      list = next;
    }
  }
  
  
  static void dischargejpc (FuncState *fs) {
    patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
    fs->jpc = NO_JUMP;
  }
  
  
  void luaK_patchlist (FuncState *fs, int list, int target) {
    if (target == fs->pc)
      luaK_patchtohere(fs, list);
    else {
      lua_assert(target < fs->pc);
      patchlistaux(fs, list, target, NO_REG, target);
    }
  }
  
  
  void luaK_patchtohere (FuncState *fs, int list) {
    luaK_getlabel(fs);
    luaK_concat(fs, &fs->jpc, list);
  }
  
  
  void luaK_concat (FuncState *fs, int *l1, int l2) {
    if (l2 == NO_JUMP) return;
    else if (*l1 == NO_JUMP)
      *l1 = l2;
    else {
      int list = *l1;
      int next;
      while ((next = getjump(fs, list)) != NO_JUMP)  /* find last element */
        list = next;
      fixjump(fs, list, l2);
    }
  }
  
  
  void luaK_checkstack (FuncState *fs, int n) {
    int newstack = fs->freereg + n;
    if (newstack > fs->f->maxstacksize) {
      if (newstack >= MAXSTACK)
        luaX_syntaxerror(fs->ls, "function or expression too complex");
      fs->f->maxstacksize = cast_byte(newstack);
    }
  }
  
  
  void luaK_reserveregs (FuncState *fs, int n) {
    luaK_checkstack(fs, n);
    fs->freereg += n;
  }
  
  
  static void freereg (FuncState *fs, int reg) {
    if (!ISK(reg) && reg >= fs->nactvar) {
      fs->freereg--;
      lua_assert(reg == fs->freereg);
    }
  }
  
  
  static void freeexp (FuncState *fs, expdesc *e) {
    if (e->k == VNONRELOC)
      freereg(fs, e->u.s.info);
  }
  
  
  static int addk (FuncState *fs, TValue *k, TValue *v) {
    lua_State *L = fs->L;
    TValue *idx = luaH_set(L, fs->h, k);
    Proto *f = fs->f;
    int oldsize = f->sizek;
    if (ttisnumber(idx)) {
      lua_assert(luaO_rawequalObj(&fs->f->k[cast_int(nvalue(idx))], v));
      return cast_int(nvalue(idx));
    }
    else {  /* constant not found; create a new entry */
      setnvalue(idx, cast_num(fs->nk));
      luaM_growvector(L, f->k, fs->nk, f->sizek, TValue,
                      MAXARG_Bx, "constant table overflow");
      while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
      setobj(L, &f->k[fs->nk], v);
      luaC_barrier(L, f, v);
      return fs->nk++;
    }
  }
  
  
  int luaK_stringK (FuncState *fs, TString *s) {
    TValue o;
    setsvalue(fs->L, &o, s);
    return addk(fs, &o, &o);
  }
  
  
  int luaK_numberK (FuncState *fs, lua_Number r) {
    TValue o;
    setnvalue(&o, r);
    return addk(fs, &o, &o);
  }
  
  
  static int boolK (FuncState *fs, int b) {
    TValue o;
    setbvalue(&o, b);
    return addk(fs, &o, &o);
  }
  
  
  static int nilK (FuncState *fs) {
    TValue k, v;
    setnilvalue(&v);
    /* cannot use nil as key; instead use table itself to represent nil */
    sethvalue(fs->L, &k, fs->h);
    return addk(fs, &k, &v);
  }
  
  
  void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
    if (e->k == VCALL) {  /* expression is an open function call? */
      SETARG_C(getcode(fs, e), nresults+1);
    }
    else if (e->k == VVARARG) {
      SETARG_B(getcode(fs, e), nresults+1);
      SETARG_A(getcode(fs, e), fs->freereg);
      luaK_reserveregs(fs, 1);
    }
  }
  
  
  void luaK_setoneret (FuncState *fs, expdesc *e) {
    if (e->k == VCALL) {  /* expression is an open function call? */
      e->k = VNONRELOC;
      e->u.s.info = GETARG_A(getcode(fs, e));
    }
    else if (e->k == VVARARG) {
      SETARG_B(getcode(fs, e), 2);
      e->k = VRELOCABLE;  /* can relocate its simple result */
    }
  }
  
  
  void luaK_dischargevars (FuncState *fs, expdesc *e) {
    switch (e->k) {
      case VLOCAL: {
        e->k = VNONRELOC;
        break;
      }
      case VUPVAL: {
        e->u.s.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.s.info, 0);
        e->k = VRELOCABLE;
        break;
      }
      case VGLOBAL: {
        e->u.s.info = luaK_codeABx(fs, OP_GETGLOBAL, 0, e->u.s.info);
        e->k = VRELOCABLE;
        break;
      }
      case VINDEXED: {
        freereg(fs, e->u.s.aux);
        freereg(fs, e->u.s.info);
        e->u.s.info = luaK_codeABC(fs, OP_GETTABLE, 0, e->u.s.info, e->u.s.aux);
        e->k = VRELOCABLE;
        break;
      }
      case VVARARG:
      case VCALL: {
        luaK_setoneret(fs, e);
        break;
      }
      default: break;  /* there is one value available (somewhere) */
    }
  }
  
  
  static int code_label (FuncState *fs, int A, int b, int jump) {
    luaK_getlabel(fs);  /* those instructions may be jump targets */
    return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
  }
  
  
  static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
    luaK_dischargevars(fs, e);
    switch (e->k) {
      case VNIL: {
        luaK_nil(fs, reg, 1);
        break;
      }
      case VFALSE:  case VTRUE: {
        luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
        break;
      }
      case VK: {
        luaK_codeABx(fs, OP_LOADK, reg, e->u.s.info);
        break;
      }
      case VKNUM: {
        luaK_codeABx(fs, OP_LOADK, reg, luaK_numberK(fs, e->u.nval));
        break;
      }
      case VRELOCABLE: {
        Instruction *pc = &getcode(fs, e);
        SETARG_A(*pc, reg);
        break;
      }
      case VNONRELOC: {
        if (reg != e->u.s.info)
          luaK_codeABC(fs, OP_MOVE, reg, e->u.s.info, 0);
        break;
      }
      default: {
        lua_assert(e->k == VVOID || e->k == VJMP);
        return;  /* nothing to do... */
      }
    }
    e->u.s.info = reg;
    e->k = VNONRELOC;
  }
  
  
  static void discharge2anyreg (FuncState *fs, expdesc *e) {
    if (e->k != VNONRELOC) {
      luaK_reserveregs(fs, 1);
      discharge2reg(fs, e, fs->freereg-1);
    }
  }
  
  
  static void exp2reg (FuncState *fs, expdesc *e, int reg) {
    discharge2reg(fs, e, reg);
    if (e->k == VJMP)
      luaK_concat(fs, &e->t, e->u.s.info);  /* put this jump in `t' list */
    if (hasjumps(e)) {
      int final;  /* position after whole expression */
      int p_f = NO_JUMP;  /* position of an eventual LOAD false */
      int p_t = NO_JUMP;  /* position of an eventual LOAD true */
      if (need_value(fs, e->t) || need_value(fs, e->f)) {
        int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
        p_f = code_label(fs, reg, 0, 1);
        p_t = code_label(fs, reg, 1, 0);
        luaK_patchtohere(fs, fj);
      }
      final = luaK_getlabel(fs);
      patchlistaux(fs, e->f, final, reg, p_f);
      patchlistaux(fs, e->t, final, reg, p_t);
    }
    e->f = e->t = NO_JUMP;
    e->u.s.info = reg;
    e->k = VNONRELOC;
  }
  
  
  void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
    luaK_dischargevars(fs, e);
    freeexp(fs, e);
    luaK_reserveregs(fs, 1);
    exp2reg(fs, e, fs->freereg - 1);
  }
  
  
  int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
    luaK_dischargevars(fs, e);
    if (e->k == VNONRELOC) {
      if (!hasjumps(e)) return e->u.s.info;  /* exp is already in a register */
      if (e->u.s.info >= fs->nactvar) {  /* reg. is not a local? */
        exp2reg(fs, e, e->u.s.info);  /* put value on it */
        return e->u.s.info;
      }
    }
    luaK_exp2nextreg(fs, e);  /* default */
    return e->u.s.info;
  }
  
  
  void luaK_exp2val (FuncState *fs, expdesc *e) {
    if (hasjumps(e))
      luaK_exp2anyreg(fs, e);
    else
      luaK_dischargevars(fs, e);
  }
  
  
  int luaK_exp2RK (FuncState *fs, expdesc *e) {
    luaK_exp2val(fs, e);
    switch (e->k) {
      case VKNUM:
      case VTRUE:
      case VFALSE:
      case VNIL: {
        if (fs->nk <= MAXINDEXRK) {  /* constant fit in RK operand? */
          e->u.s.info = (e->k == VNIL)  ? nilK(fs) :
                        (e->k == VKNUM) ? luaK_numberK(fs, e->u.nval) :
                                          boolK(fs, (e->k == VTRUE));
          e->k = VK;
          return RKASK(e->u.s.info);
        }
        else break;
      }
      case VK: {
        if (e->u.s.info <= MAXINDEXRK)  /* constant fit in argC? */
          return RKASK(e->u.s.info);
        else break;
      }
      default: break;
    }
    /* not a constant in the right range: put it in a register */
    return luaK_exp2anyreg(fs, e);
  }
  
  
  void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
    switch (var->k) {
      case VLOCAL: {
        freeexp(fs, ex);
        exp2reg(fs, ex, var->u.s.info);
        return;
      }
      case VUPVAL: {
        int e = luaK_exp2anyreg(fs, ex);
        luaK_codeABC(fs, OP_SETUPVAL, e, var->u.s.info, 0);
        break;
      }
      case VGLOBAL: {
        int e = luaK_exp2anyreg(fs, ex);
        luaK_codeABx(fs, OP_SETGLOBAL, e, var->u.s.info);
        break;
      }
      case VINDEXED: {
        int e = luaK_exp2RK(fs, ex);
        luaK_codeABC(fs, OP_SETTABLE, var->u.s.info, var->u.s.aux, e);
        break;
      }
      default: {
        lua_assert(0);  /* invalid var kind to store */
        break;
      }
    }
    freeexp(fs, ex);
  }
  
  
  void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
    int func;
    luaK_exp2anyreg(fs, e);
    freeexp(fs, e);
    func = fs->freereg;
    luaK_reserveregs(fs, 2);
    luaK_codeABC(fs, OP_SELF, func, e->u.s.info, luaK_exp2RK(fs, key));
    freeexp(fs, key);
    e->u.s.info = func;
    e->k = VNONRELOC;
  }
  
  
  static void invertjump (FuncState *fs, expdesc *e) {
    Instruction *pc = getjumpcontrol(fs, e->u.s.info);
    lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
                                             GET_OPCODE(*pc) != OP_TEST);
    SETARG_A(*pc, !(GETARG_A(*pc)));
  }
  
  
  static int jumponcond (FuncState *fs, expdesc *e, int cond) {
    if (e->k == VRELOCABLE) {
      Instruction ie = getcode(fs, e);
      if (GET_OPCODE(ie) == OP_NOT) {
        fs->pc--;  /* remove previous OP_NOT */
        return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
      }
      /* else go through */
    }
    discharge2anyreg(fs, e);
    freeexp(fs, e);
    return condjump(fs, OP_TESTSET, NO_REG, e->u.s.info, cond);
  }
  
  
  void luaK_goiftrue (FuncState *fs, expdesc *e) {
    int pc;  /* pc of last jump */
    luaK_dischargevars(fs, e);
    switch (e->k) {
      case VK: case VKNUM: case VTRUE: {
        pc = NO_JUMP;  /* always true; do nothing */
        break;
      }
      case VFALSE: {
        pc = luaK_jump(fs);  /* always jump */
        break;
      }
      case VJMP: {
        invertjump(fs, e);
        pc = e->u.s.info;
        break;
      }
      default: {
        pc = jumponcond(fs, e, 0);
        break;
      }
    }
    luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
    luaK_patchtohere(fs, e->t);
    e->t = NO_JUMP;
  }
  
  
  static void luaK_goiffalse (FuncState *fs, expdesc *e) {
    int pc;  /* pc of last jump */
    luaK_dischargevars(fs, e);
    switch (e->k) {
      case VNIL: case VFALSE: {
        pc = NO_JUMP;  /* always false; do nothing */
        break;
      }
      case VTRUE: {
        pc = luaK_jump(fs);  /* always jump */
        break;
      }
      case VJMP: {
        pc = e->u.s.info;
        break;
      }
      default: {
        pc = jumponcond(fs, e, 1);
        break;
      }
    }
    luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
    luaK_patchtohere(fs, e->f);
    e->f = NO_JUMP;
  }
  
  
  static void codenot (FuncState *fs, expdesc *e) {
    luaK_dischargevars(fs, e);
    switch (e->k) {
      case VNIL: case VFALSE: {
        e->k = VTRUE;
        break;
      }
      case VK: case VKNUM: case VTRUE: {
        e->k = VFALSE;
        break;
      }
      case VJMP: {
        invertjump(fs, e);
        break;
      }
      case VRELOCABLE:
      case VNONRELOC: {
        discharge2anyreg(fs, e);
        freeexp(fs, e);
        e->u.s.info = luaK_codeABC(fs, OP_NOT, 0, e->u.s.info, 0);
        e->k = VRELOCABLE;
        break;
      }
      default: {
        lua_assert(0);  /* cannot happen */
        break;
      }
    }
    /* interchange true and false lists */
    { int temp = e->f; e->f = e->t; e->t = temp; }
    removevalues(fs, e->f);
    removevalues(fs, e->t);
  }
  
  
  void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
    t->u.s.aux = luaK_exp2RK(fs, k);
    t->k = VINDEXED;
  }
  
  
  static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
    lua_Number v1, v2, r;
    if (!isnumeral(e1) || !isnumeral(e2)) return 0;
    v1 = e1->u.nval;
    v2 = e2->u.nval;
    switch (op) {
      case OP_ADD: r = luai_numadd(v1, v2); break;
      case OP_SUB: r = luai_numsub(v1, v2); break;
      case OP_MUL: r = luai_nummul(v1, v2); break;
      case OP_DIV:
        if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
        r = luai_numdiv(v1, v2); break;
      case OP_MOD:
        if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
        r = luai_nummod(v1, v2); break;
      case OP_POW: r = luai_numpow(v1, v2); break;
      case OP_UNM: r = luai_numunm(v1); break;
      case OP_LEN: return 0;  /* no constant folding for 'len' */
      default: lua_assert(0); r = 0; break;
    }
    if (luai_numisnan(r)) return 0;  /* do not attempt to produce NaN */
    e1->u.nval = r;
    return 1;
  }
  
  
  static void codearith (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2) {
    if (constfolding(op, e1, e2))
      return;
    else {
      int o2 = (op != OP_UNM && op != OP_LEN) ? luaK_exp2RK(fs, e2) : 0;
      int o1 = luaK_exp2RK(fs, e1);
      if (o1 > o2) {
        freeexp(fs, e1);
        freeexp(fs, e2);
      }
      else {
        freeexp(fs, e2);
        freeexp(fs, e1);
      }
      e1->u.s.info = luaK_codeABC(fs, op, 0, o1, o2);
      e1->k = VRELOCABLE;
    }
  }
  
  
  static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
                                                            expdesc *e2) {
    int o1 = luaK_exp2RK(fs, e1);
    int o2 = luaK_exp2RK(fs, e2);
    freeexp(fs, e2);
    freeexp(fs, e1);
    if (cond == 0 && op != OP_EQ) {
      int temp;  /* exchange args to replace by `<' or `<=' */
      temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
      cond = 1;
    }
    e1->u.s.info = condjump(fs, op, cond, o1, o2);
    e1->k = VJMP;
  }
  
  
  void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e) {
    expdesc e2;
    e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
    switch (op) {
      case OPR_MINUS: {
        if (!isnumeral(e))
          luaK_exp2anyreg(fs, e);  /* cannot operate on non-numeric constants */
        codearith(fs, OP_UNM, e, &e2);
        break;
      }
      case OPR_NOT: codenot(fs, e); break;
      case OPR_LEN: {
        luaK_exp2anyreg(fs, e);  /* cannot operate on constants */
        codearith(fs, OP_LEN, e, &e2);
        break;
      }
      default: lua_assert(0);
    }
  }
  
  
  void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
    switch (op) {
      case OPR_AND: {
        luaK_goiftrue(fs, v);
        break;
      }
      case OPR_OR: {
        luaK_goiffalse(fs, v);
        break;
      }
      case OPR_CONCAT: {
        luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
        break;
      }
      case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
      case OPR_MOD: case OPR_POW: {
        if (!isnumeral(v)) luaK_exp2RK(fs, v);
        break;
      }
      default: {
        luaK_exp2RK(fs, v);
        break;
      }
    }
  }
  
  
  void luaK_posfix (FuncState *fs, BinOpr op, expdesc *e1, expdesc *e2) {
    switch (op) {
      case OPR_AND: {
        lua_assert(e1->t == NO_JUMP);  /* list must be closed */
        luaK_dischargevars(fs, e2);
        luaK_concat(fs, &e2->f, e1->f);
        *e1 = *e2;
        break;
      }
      case OPR_OR: {
        lua_assert(e1->f == NO_JUMP);  /* list must be closed */
        luaK_dischargevars(fs, e2);
        luaK_concat(fs, &e2->t, e1->t);
        *e1 = *e2;
        break;
      }
      case OPR_CONCAT: {
        luaK_exp2val(fs, e2);
        if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
          lua_assert(e1->u.s.info == GETARG_B(getcode(fs, e2))-1);
          freeexp(fs, e1);
          SETARG_B(getcode(fs, e2), e1->u.s.info);
          e1->k = VRELOCABLE; e1->u.s.info = e2->u.s.info;
        }
        else {
          luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
          codearith(fs, OP_CONCAT, e1, e2);
        }
        break;
      }
      case OPR_ADD: codearith(fs, OP_ADD, e1, e2); break;
      case OPR_SUB: codearith(fs, OP_SUB, e1, e2); break;
      case OPR_MUL: codearith(fs, OP_MUL, e1, e2); break;
      case OPR_DIV: codearith(fs, OP_DIV, e1, e2); break;
      case OPR_MOD: codearith(fs, OP_MOD, e1, e2); break;
      case OPR_POW: codearith(fs, OP_POW, e1, e2); break;
      case OPR_EQ: codecomp(fs, OP_EQ, 1, e1, e2); break;
      case OPR_NE: codecomp(fs, OP_EQ, 0, e1, e2); break;
      case OPR_LT: codecomp(fs, OP_LT, 1, e1, e2); break;
      case OPR_LE: codecomp(fs, OP_LE, 1, e1, e2); break;
      case OPR_GT: codecomp(fs, OP_LT, 0, e1, e2); break;
      case OPR_GE: codecomp(fs, OP_LE, 0, e1, e2); break;
      default: lua_assert(0);
    }
  }
  
  
  void luaK_fixline (FuncState *fs, int line) {
    fs->f->lineinfo[fs->pc - 1] = line;
  }
  
  
  static int luaK_code (FuncState *fs, Instruction i, int line) {
    Proto *f = fs->f;
    dischargejpc(fs);  /* `pc' will change */
    /* put new instruction in code array */
    luaM_growvector(fs->L, f->code, fs->pc, f->sizecode, Instruction,
                    MAX_INT, "code size overflow");
    f->code[fs->pc] = i;
    /* save corresponding line information */
    luaM_growvector(fs->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
                    MAX_INT, "code size overflow");
    f->lineinfo[fs->pc] = line;
    return fs->pc++;
  }
  
  
  int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
    lua_assert(getOpMode(o) == iABC);
    lua_assert(getBMode(o) != OpArgN || b == 0);
    lua_assert(getCMode(o) != OpArgN || c == 0);
    return luaK_code(fs, CREATE_ABC(o, a, b, c), fs->ls->lastline);
  }
  
  
  int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
    lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
    lua_assert(getCMode(o) == OpArgN);
    return luaK_code(fs, CREATE_ABx(o, a, bc), fs->ls->lastline);
  }
  
  
  void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
    int c =  (nelems - 1)/LFIELDS_PER_FLUSH + 1;
    int b = (tostore == LUA_MULTRET) ? 0 : tostore;
    lua_assert(tostore != 0);
    if (c <= MAXARG_C)
      luaK_codeABC(fs, OP_SETLIST, base, b, c);
    else {
      luaK_codeABC(fs, OP_SETLIST, base, b, 0);
      luaK_code(fs, cast(Instruction, c), fs->ls->lastline);
    }
    fs->freereg = base + 1;  /* free registers with list values */
  }
  
  