/*

** $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);