lcode.c

世界上最快的脚本语言lua的源码

/*
** $Id: lcode.c,v 1.117 2003/04/03 13:35:34 roberto Exp $
** Code generator for Lua
** See Copyright Notice in lua.h
*/


#include <stdlib.h>

#define lcode_c

#include "lua.h"

#include "lcode.h"
#include "ldebug.h"
#include "ldo.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)


void luaK_nil (FuncState *fs, int from, int n) {
  Instruction *previous;
  if (fs->pc > fs->lasttarget &&  /* no jumps to current position? */
      GET_OPCODE(*(previous = &fs->f->code[fs->pc-1])) == 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;
}


static int luaK_condjump (FuncState *fs, OpCode op, int A, int B, int C) {
  luaK_codeABC(fs, op, A, B, C);
  return luaK_jump(fs);
}


static void luaK_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 luaK_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 && testOpMode(GET_OPCODE(*(pi-1)), OpModeT))
    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, int cond) {
  for (; list != NO_JUMP; list = luaK_getjump(fs, list)) {
    Instruction i = *getjumpcontrol(fs, list);
    if (GET_OPCODE(i) != OP_TEST || GETARG_C(i) != cond) return 1;
  }
  return 0;  /* not found */
}


static void patchtestreg (Instruction *i, int reg) {
  if (reg == NO_REG) reg = GETARG_B(*i);
  SETARG_A(*i, reg);
}


static void luaK_patchlistaux (FuncState *fs, int list,
          int ttarget, int treg, int ftarget, int freg, int dtarget) {
  while (list != NO_JUMP) {
    int next = luaK_getjump(fs, list);
    Instruction *i = getjumpcontrol(fs, list);
    if (GET_OPCODE(*i) != OP_TEST) {
      lua_assert(dtarget != NO_JUMP);
      luaK_fixjump(fs, list, dtarget);  /* jump to default target */
    }
    else {
      if (GETARG_C(*i)) {
        lua_assert(ttarget != NO_JUMP);
        patchtestreg(i, treg);
        luaK_fixjump(fs, list, ttarget);
      }
      else {
        lua_assert(ftarget != NO_JUMP);
        patchtestreg(i, freg);
        luaK_fixjump(fs, list, ftarget);
      }
    }
    list = next;
  }
}


static void luaK_dischargejpc (FuncState *fs) {
  luaK_patchlistaux(fs, fs->jpc, fs->pc, NO_REG, 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);
    luaK_patchlistaux(fs, list, target, NO_REG, 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 = luaK_getjump(fs, list)) != NO_JUMP)  /* find last element */
      list = next;
    luaK_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(lu_byte, newstack);
  }
}


void luaK_reserveregs (FuncState *fs, int n) {
  luaK_checkstack(fs, n);
  fs->freereg += n;
}


static void freereg (FuncState *fs, int reg) {
  if (reg >= fs->nactvar && reg < MAXSTACK) {
    fs->freereg--;
    lua_assert(reg == fs->freereg);
  }
}


static void freeexp (FuncState *fs, expdesc *e) {
  if (e->k == VNONRELOC)
    freereg(fs, e->info);
}


static int addk (FuncState *fs, TObject *k, TObject *v) {
  const TObject *idx = luaH_get(fs->h, k);
  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 */
    Proto *f = fs->f;
    luaM_growvector(fs->L, f->k, fs->nk, f->sizek, TObject,
                    MAXARG_Bx, "constant table overflow");
    setobj2n(&f->k[fs->nk], v);
    setnvalue(luaH_set(fs->L, fs->h, k), cast(lua_Number, fs->nk));
    return fs->nk++;
  }
}


int luaK_stringK (FuncState *fs, TString *s) {
  TObject o;
  setsvalue(&o, s);
  return addk(fs, &o, &o);
}


int luaK_numberK (FuncState *fs, lua_Number r) {
  TObject o;
  setnvalue(&o, r);
  return addk(fs, &o, &o);
}


static int nil_constant (FuncState *fs) {
  TObject k, v;
  setnilvalue(&v);
  sethvalue(&k, fs->h);  /* cannot use nil as key; instead use table itself */
  return addk(fs, &k, &v);
}


void luaK_setcallreturns (FuncState *fs, expdesc *e, int nresults) {
  if (e->k == VCALL) {  /* expression is an open function call? */
    SETARG_C(getcode(fs, e), nresults+1);
    if (nresults == 1) {  /* `regular' expression? */
      e->k = VNONRELOC;
      e->info = GETARG_A(getcode(fs, e));
    }
  }
}


void luaK_dischargevars (FuncState *fs, expdesc *e) {
  switch (e->k) {
    case VLOCAL: {
      e->k = VNONRELOC;
      break;
    }
    case VUPVAL: {
      e->info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->info, 0);
      e->k = VRELOCABLE;
      break;
    }
    case VGLOBAL: {
      e->info = luaK_codeABx(fs, OP_GETGLOBAL, 0, e->info);
      e->k = VRELOCABLE;
      break;
    }
    case VINDEXED: {
      freereg(fs, e->aux);
      freereg(fs, e->info);
      e->info = luaK_codeABC(fs, OP_GETTABLE, 0, e->info, e->aux);
      e->k = VRELOCABLE;
      break;
    }
    case VCALL: {
      luaK_setcallreturns(fs, e, 1);
      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->info);
      break;
    }
    case VRELOCABLE: {
      Instruction *pc = &getcode(fs, e);
      SETARG_A(*pc, reg);
      break;
    }
    case VNONRELOC: {
      if (reg != e->info)
        luaK_codeABC(fs, OP_MOVE, reg, e->info, 0);
      break;
    }
    default: {
      lua_assert(e->k == VVOID || e->k == VJMP);
      return;  /* nothing to do... */
    }
  }
  e->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 luaK_exp2reg (FuncState *fs, expdesc *e, int reg) {
  discharge2reg(fs, e, reg);
  if (e->k == VJMP)
    luaK_concat(fs, &e->t, e->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, 1) || need_value(fs, e->f, 0)) {
      int fj = NO_JUMP;  /* first jump (over LOAD ops.) */
      if (e->k != VJMP)
        fj = 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);
    luaK_patchlistaux(fs, e->f, p_f, NO_REG, final, reg, p_f);
    luaK_patchlistaux(fs, e->t, final, reg, p_t, NO_REG, p_t);