lua/lcode.c
changeset 0 d7ee4e2ed49d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lua/lcode.c	Tue Dec 17 22:16:27 2013 -0500
@@ -0,0 +1,881 @@
+/*
+** $Id: lcode.c,v 2.62.1.1 2013/04/12 18:48:47 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 "lstring.h"
+#include "ltable.h"
+#include "lvm.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;
+  int l = from + n - 1;  /* last register to set nil */
+  if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
+    previous = &fs->f->code[fs->pc-1];
+    if (GET_OPCODE(*previous) == OP_LOADNIL) {
+      int pfrom = GETARG_A(*previous);
+      int pl = pfrom + GETARG_B(*previous);
+      if ((pfrom <= from && from <= pl + 1) ||
+          (from <= pfrom && pfrom <= l + 1)) {  /* can connect both? */
+        if (pfrom < from) from = pfrom;  /* from = min(from, pfrom) */
+        if (pl > l) l = pl;  /* l = max(l, pl) */
+        SETARG_A(*previous, from);
+        SETARG_B(*previous, l - from);
+        return;
+      }
+    }  /* else go through */
+  }
+  luaK_codeABC(fs, OP_LOADNIL, 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);
+  }
+}
+
+
+LUAI_FUNC void luaK_patchclose (FuncState *fs, int list, int level) {
+  level++;  /* argument is +1 to reserve 0 as non-op */
+  while (list != NO_JUMP) {
+    int next = getjump(fs, list);
+    lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP &&
+                (GETARG_A(fs->f->code[list]) == 0 ||
+                 GETARG_A(fs->f->code[list]) >= level));
+    SETARG_A(fs->f->code[list], level);
+    list = next;
+  }
+}
+
+
+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);
+  }
+}
+
+
+static int luaK_code (FuncState *fs, Instruction i) {
+  Proto *f = fs->f;
+  dischargejpc(fs);  /* `pc' will change */
+  /* put new instruction in code array */
+  luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,
+                  MAX_INT, "opcodes");
+  f->code[fs->pc] = i;
+  /* save corresponding line information */
+  luaM_growvector(fs->ls->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
+                  MAX_INT, "opcodes");
+  f->lineinfo[fs->pc] = fs->ls->lastline;
+  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);
+  lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);
+  return luaK_code(fs, CREATE_ABC(o, a, b, c));
+}
+
+
+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);
+  lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
+  return luaK_code(fs, CREATE_ABx(o, a, bc));
+}
+
+
+static int codeextraarg (FuncState *fs, int a) {
+  lua_assert(a <= MAXARG_Ax);
+  return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a));
+}
+
+
+int luaK_codek (FuncState *fs, int reg, int k) {
+  if (k <= MAXARG_Bx)
+    return luaK_codeABx(fs, OP_LOADK, reg, k);
+  else {
+    int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);
+    codeextraarg(fs, k);
+    return p;
+  }
+}
+
+
+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.info);
+}
+
+
+static int addk (FuncState *fs, TValue *key, TValue *v) {
+  lua_State *L = fs->ls->L;
+  TValue *idx = luaH_set(L, fs->h, key);
+  Proto *f = fs->f;
+  int k, oldsize;
+  if (ttisnumber(idx)) {
+    lua_Number n = nvalue(idx);
+    lua_number2int(k, n);
+    if (luaV_rawequalobj(&f->k[k], v))
+      return k;
+    /* else may be a collision (e.g., between 0.0 and "\0\0\0\0\0\0\0\0");
+       go through and create a new entry for this value */
+  }
+  /* constant not found; create a new entry */
+  oldsize = f->sizek;
+  k = fs->nk;
+  /* numerical value does not need GC barrier;
+     table has no metatable, so it does not need to invalidate cache */
+  setnvalue(idx, cast_num(k));
+  luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");
+  while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
+  setobj(L, &f->k[k], v);
+  fs->nk++;
+  luaC_barrier(L, f, v);
+  return k;
+}
+
+
+int luaK_stringK (FuncState *fs, TString *s) {
+  TValue o;
+  setsvalue(fs->ls->L, &o, s);
+  return addk(fs, &o, &o);
+}
+
+
+int luaK_numberK (FuncState *fs, lua_Number r) {
+  int n;
+  lua_State *L = fs->ls->L;
+  TValue o;
+  setnvalue(&o, r);
+  if (r == 0 || luai_numisnan(NULL, r)) {  /* handle -0 and NaN */
+    /* use raw representation as key to avoid numeric problems */
+    setsvalue(L, L->top++, luaS_newlstr(L, (char *)&r, sizeof(r)));
+    n = addk(fs, L->top - 1, &o);
+    L->top--;
+  }
+  else
+    n = addk(fs, &o, &o);  /* regular case */
+  return n;
+}
+
+
+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->ls->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.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.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
+      e->k = VRELOCABLE;
+      break;
+    }
+    case VINDEXED: {
+      OpCode op = OP_GETTABUP;  /* assume 't' is in an upvalue */
+      freereg(fs, e->u.ind.idx);
+      if (e->u.ind.vt == VLOCAL) {  /* 't' is in a register? */
+        freereg(fs, e->u.ind.t);
+        op = OP_GETTABLE;
+      }
+      e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx);
+      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_codek(fs, reg, e->u.info);
+      break;
+    }
+    case VKNUM: {
+      luaK_codek(fs, 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.info)
+        luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
+      break;
+    }
+    default: {
+      lua_assert(e->k == VVOID || e->k == VJMP);
+      return;  /* nothing to do... */
+    }
+  }
+  e->u.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.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.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.info;  /* exp is already in a register */
+    if (e->u.info >= fs->nactvar) {  /* reg. is not a local? */
+      exp2reg(fs, e, e->u.info);  /* put value on it */
+      return e->u.info;
+    }
+  }
+  luaK_exp2nextreg(fs, e);  /* default */
+  return e->u.info;
+}
+
+
+void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
+  if (e->k != VUPVAL || hasjumps(e))
+    luaK_exp2anyreg(fs, e);
+}
+
+
+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 VTRUE:
+    case VFALSE:
+    case VNIL: {
+      if (fs->nk <= MAXINDEXRK) {  /* constant fits in RK operand? */
+        e->u.info = (e->k == VNIL) ? nilK(fs) : boolK(fs, (e->k == VTRUE));
+        e->k = VK;
+        return RKASK(e->u.info);
+      }
+      else break;
+    }
+    case VKNUM: {
+      e->u.info = luaK_numberK(fs, e->u.nval);
+      e->k = VK;
+      /* go through */
+    }
+    case VK: {
+      if (e->u.info <= MAXINDEXRK)  /* constant fits in argC? */
+        return RKASK(e->u.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.info);
+      return;
+    }
+    case VUPVAL: {
+      int e = luaK_exp2anyreg(fs, ex);
+      luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
+      break;
+    }
+    case VINDEXED: {
+      OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;
+      int e = luaK_exp2RK(fs, ex);
+      luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, 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 ereg;
+  luaK_exp2anyreg(fs, e);
+  ereg = e->u.info;  /* register where 'e' was placed */
+  freeexp(fs, e);
+  e->u.info = fs->freereg;  /* base register for op_self */
+  e->k = VNONRELOC;
+  luaK_reserveregs(fs, 2);  /* function and 'self' produced by op_self */
+  luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));
+  freeexp(fs, key);
+}
+
+
+static void invertjump (FuncState *fs, expdesc *e) {
+  Instruction *pc = getjumpcontrol(fs, e->u.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.info, cond);
+}
+
+
+void luaK_goiftrue (FuncState *fs, expdesc *e) {
+  int pc;  /* pc of last jump */
+  luaK_dischargevars(fs, e);
+  switch (e->k) {
+    case VJMP: {
+      invertjump(fs, e);
+      pc = e->u.info;
+      break;
+    }
+    case VK: case VKNUM: case VTRUE: {
+      pc = NO_JUMP;  /* always true; do nothing */
+      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;
+}
+
+
+void luaK_goiffalse (FuncState *fs, expdesc *e) {
+  int pc;  /* pc of last jump */
+  luaK_dischargevars(fs, e);
+  switch (e->k) {
+    case VJMP: {
+      pc = e->u.info;
+      break;
+    }
+    case VNIL: case VFALSE: {
+      pc = NO_JUMP;  /* always false; do nothing */
+      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.info = luaK_codeABC(fs, OP_NOT, 0, e->u.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) {
+  lua_assert(!hasjumps(t));
+  t->u.ind.t = t->u.info;
+  t->u.ind.idx = luaK_exp2RK(fs, k);
+  t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL
+                                 : check_exp(vkisinreg(t->k), VLOCAL);
+  t->k = VINDEXED;
+}
+
+
+static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
+  lua_Number r;
+  if (!isnumeral(e1) || !isnumeral(e2)) return 0;
+  if ((op == OP_DIV || op == OP_MOD) && e2->u.nval == 0)
+    return 0;  /* do not attempt to divide by 0 */
+  r = luaO_arith(op - OP_ADD + LUA_OPADD, e1->u.nval, e2->u.nval);
+  e1->u.nval = r;
+  return 1;
+}
+
+
+static void codearith (FuncState *fs, OpCode op,
+                       expdesc *e1, expdesc *e2, int line) {
+  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.info = luaK_codeABC(fs, op, 0, o1, o2);
+    e1->k = VRELOCABLE;
+    luaK_fixline(fs, line);
+  }
+}
+
+
+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.info = condjump(fs, op, cond, o1, o2);
+  e1->k = VJMP;
+}
+
+
+void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) {
+  expdesc e2;
+  e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
+  switch (op) {
+    case OPR_MINUS: {
+      if (isnumeral(e))  /* minus constant? */
+        e->u.nval = luai_numunm(NULL, e->u.nval);  /* fold it */
+      else {
+        luaK_exp2anyreg(fs, e);
+        codearith(fs, OP_UNM, e, &e2, line);
+      }
+      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, line);
+      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, int line) {
+  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.info == GETARG_B(getcode(fs, e2))-1);
+        freeexp(fs, e1);
+        SETARG_B(getcode(fs, e2), e1->u.info);
+        e1->k = VRELOCABLE; e1->u.info = e2->u.info;
+      }
+      else {
+        luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
+        codearith(fs, OP_CONCAT, e1, e2, line);
+      }
+      break;
+    }
+    case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
+    case OPR_MOD: case OPR_POW: {
+      codearith(fs, cast(OpCode, op - OPR_ADD + OP_ADD), e1, e2, line);
+      break;
+    }
+    case OPR_EQ: case OPR_LT: case OPR_LE: {
+      codecomp(fs, cast(OpCode, op - OPR_EQ + OP_EQ), 1, e1, e2);
+      break;
+    }
+    case OPR_NE: case OPR_GT: case OPR_GE: {
+      codecomp(fs, cast(OpCode, op - OPR_NE + OP_EQ), 0, e1, e2);
+      break;
+    }
+    default: lua_assert(0);
+  }
+}
+
+
+void luaK_fixline (FuncState *fs, int line) {
+  fs->f->lineinfo[fs->pc - 1] = line;
+}
+
+
+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 if (c <= MAXARG_Ax) {
+    luaK_codeABC(fs, OP_SETLIST, base, b, 0);
+    codeextraarg(fs, c);
+  }
+  else
+    luaX_syntaxerror(fs->ls, "constructor too long");
+  fs->freereg = base + 1;  /* free registers with list values */
+}
+