/*
** $Id: lcode.c,v 2.25.1.5 2011/01/31 14:53:16 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 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 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 */
}
