add support for local variable declared with attribute 'close' and 'const' for Lua 5.4.

1 files changed, 673 insertions, 327 deletions

diff --git a/src/lua-5.3/lparser.c b/src/lua/lparser.c
index cc54de4..bc7d9a4 100644
--- a/src/lua-5.3/lparser.c
+++ b/src/lua/lparser.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lparser.c,v 2.155.1.2 2017/04/29 18:11:40 roberto Exp $
+** $Id: lparser.c $
 ** Lua Parser
 ** See Copyright Notice in lua.h
 */
@@ -10,6 +10,7 @@
 #include "lprefix.h"
 
 
+#include <limits.h>
 #include <string.h>
 
 #include "lua.h"
@@ -52,6 +53,7 @@ typedef struct BlockCnt {
   lu_byte nactvar;  /* # active locals outside the block */
   lu_byte upval;  /* true if some variable in the block is an upvalue */
   lu_byte isloop;  /* true if 'block' is a loop */
+  lu_byte insidetbc;  /* true if inside the scope of a to-be-closed var. */
 } BlockCnt;
 
 
@@ -63,13 +65,6 @@ static void statement (LexState *ls);
 static void expr (LexState *ls, expdesc *v);
 
 
-/* semantic error */
-static l_noret semerror (LexState *ls, const char *msg) {
-  ls->t.token = 0;  /* remove "near <token>" from final message */
-  luaX_syntaxerror(ls, msg);
-}
-
-
 static l_noret error_expected (LexState *ls, int token) {
   luaX_syntaxerror(ls,
       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
@@ -94,6 +89,9 @@ static void checklimit (FuncState *fs, int v, int l, const char *what) {
 }
 
 
+/*
+** Test whether next token is 'c'; if so, skip it.
+*/
 static int testnext (LexState *ls, int c) {
   if (ls->t.token == c) {
     luaX_next(ls);
@@ -103,12 +101,18 @@ static int testnext (LexState *ls, int c) {
 }
 
 
+/*
+** Check that next token is 'c'.
+*/
 static void check (LexState *ls, int c) {
   if (ls->t.token != c)
     error_expected(ls, c);
 }
 
 
+/*
+** Check that next token is 'c' and skip it.
+*/
 static void checknext (LexState *ls, int c) {
   check(ls, c);
   luaX_next(ls);
@@ -118,11 +122,15 @@ static void checknext (LexState *ls, int c) {
 #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
 
 
-
+/*
+** Check that next token is 'what' and skip it. In case of error,
+** raise an error that the expected 'what' should match a 'who'
+** in line 'where' (if that is not the current line).
+*/
 static void check_match (LexState *ls, int what, int who, int where) {
-  if (!testnext(ls, what)) {
-    if (where == ls->linenumber)
-      error_expected(ls, what);
+  if (unlikely(!testnext(ls, what))) {
+    if (where == ls->linenumber)  /* all in the same line? */
+      error_expected(ls, what);  /* do not need a complex message */
     else {
       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
              "%s expected (to close %s at line %d)",
@@ -148,73 +156,189 @@ static void init_exp (expdesc *e, expkind k, int i) {
 }
 
 
-static void codestring (LexState *ls, expdesc *e, TString *s) {
-  init_exp(e, VK, luaK_stringK(ls->fs, s));
+static void codestring (expdesc *e, TString *s) {
+  e->f = e->t = NO_JUMP;
+  e->k = VKSTR;
+  e->u.strval = s;
 }
 
 
-static void checkname (LexState *ls, expdesc *e) {
-  codestring(ls, e, str_checkname(ls));
+static void codename (LexState *ls, expdesc *e) {
+  codestring(e, str_checkname(ls));
 }
 
 
-static int registerlocalvar (LexState *ls, TString *varname) {
-  FuncState *fs = ls->fs;
+/*
+** Register a new local variable in the active 'Proto' (for debug
+** information).
+*/
+static int registerlocalvar (LexState *ls, FuncState *fs, TString *varname) {
   Proto *f = fs->f;
   int oldsize = f->sizelocvars;
-  luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
+  luaM_growvector(ls->L, f->locvars, fs->ndebugvars, f->sizelocvars,
                   LocVar, SHRT_MAX, "local variables");
   while (oldsize < f->sizelocvars)
     f->locvars[oldsize++].varname = NULL;
-  f->locvars[fs->nlocvars].varname = varname;
+  f->locvars[fs->ndebugvars].varname = varname;
+  f->locvars[fs->ndebugvars].startpc = fs->pc;
   luaC_objbarrier(ls->L, f, varname);
-  return fs->nlocvars++;
+  return fs->ndebugvars++;
 }
 
 
-static void new_localvar (LexState *ls, TString *name) {
+/*
+** Create a new local variable with the given 'name'. Return its index
+** in the function.
+*/
+static int new_localvar (LexState *ls, TString *name) {
+  lua_State *L = ls->L;
   FuncState *fs = ls->fs;
   Dyndata *dyd = ls->dyd;
-  int reg = registerlocalvar(ls, name);
+  Vardesc *var;
   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
-                  MAXVARS, "local variables");
-  luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
-                  dyd->actvar.size, Vardesc, MAX_INT, "local variables");
-  dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
+                 MAXVARS, "local variables");
+  luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
+                  dyd->actvar.size, Vardesc, USHRT_MAX, "local variables");
+  var = &dyd->actvar.arr[dyd->actvar.n++];
+  var->vd.kind = VDKREG;  /* default */
+  var->vd.name = name;
+  return dyd->actvar.n - 1 - fs->firstlocal;
 }
 
+#define new_localvarliteral(ls,v) \
+    new_localvar(ls,  \
+      luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char)) - 1));
+
 
-static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
-  new_localvar(ls, luaX_newstring(ls, name, sz));
+
+/*
+** Return the "variable description" (Vardesc) of a given variable.
+** (Unless noted otherwise, all variables are referred to by their
+** compiler indices.)
+*/
+static Vardesc *getlocalvardesc (FuncState *fs, int vidx) {
+  return &fs->ls->dyd->actvar.arr[fs->firstlocal + vidx];
 }
 
-#define new_localvarliteral(ls,v) \
-        new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
+
+/*
+** Convert 'nvar', a compiler index level, to it corresponding
+** stack index level. For that, search for the highest variable
+** below that level that is in the stack and uses its stack
+** index ('sidx').
+*/
+static int stacklevel (FuncState *fs, int nvar) {
+  while (nvar-- > 0) {
+    Vardesc *vd = getlocalvardesc(fs, nvar);  /* get variable */
+    if (vd->vd.kind != RDKCTC)  /* is in the stack? */
+      return vd->vd.sidx + 1;
+  }
+  return 0;  /* no variables in the stack */
+}
+
+
+/*
+** Return the number of variables in the stack for function 'fs'
+*/
+int luaY_nvarstack (FuncState *fs) {
+  return stacklevel(fs, fs->nactvar);
+}
 
 
-static LocVar *getlocvar (FuncState *fs, int i) {
-  int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
-  lua_assert(idx < fs->nlocvars);
-  return &fs->f->locvars[idx];
+/*
+** Get the debug-information entry for current variable 'vidx'.
+*/
+static LocVar *localdebuginfo (FuncState *fs, int vidx) {
+  Vardesc *vd = getlocalvardesc(fs,  vidx);
+  if (vd->vd.kind == RDKCTC)
+    return NULL;  /* no debug info. for constants */
+  else {
+    int idx = vd->vd.pidx;
+    lua_assert(idx < fs->ndebugvars);
+    return &fs->f->locvars[idx];
+  }
 }
 
 
+/*
+** Create an expression representing variable 'vidx'
+*/
+static void init_var (FuncState *fs, expdesc *e, int vidx) {
+  e->f = e->t = NO_JUMP;
+  e->k = VLOCAL;
+  e->u.var.vidx = vidx;
+  e->u.var.sidx = getlocalvardesc(fs, vidx)->vd.sidx;
+}
+
+
+/*
+** Raises an error if variable described by 'e' is read only
+*/
+static void check_readonly (LexState *ls, expdesc *e) {
+  FuncState *fs = ls->fs;
+  TString *varname = NULL;  /* to be set if variable is const */
+  switch (e->k) {
+    case VCONST: {
+      varname = ls->dyd->actvar.arr[e->u.info].vd.name;
+      break;
+    }
+    case VLOCAL: {
+      Vardesc *vardesc = getlocalvardesc(fs, e->u.var.vidx);
+      if (vardesc->vd.kind != VDKREG)  /* not a regular variable? */
+        varname = vardesc->vd.name;
+      break;
+    }
+    case VUPVAL: {
+      Upvaldesc *up = &fs->f->upvalues[e->u.info];
+      if (up->kind != VDKREG)
+        varname = up->name;
+      break;
+    }
+    default:
+      return;  /* other cases cannot be read-only */
+  }
+  if (varname) {
+    const char *msg = luaO_pushfstring(ls->L,
+       "attempt to assign to const variable '%s'", getstr(varname));
+    luaK_semerror(ls, msg);  /* error */
+  }
+}
+
+
+/*
+** Start the scope for the last 'nvars' created variables.
+*/
 static void adjustlocalvars (LexState *ls, int nvars) {
   FuncState *fs = ls->fs;
-  fs->nactvar = cast_byte(fs->nactvar + nvars);
-  for (; nvars; nvars--) {
-    getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
+  int stklevel = luaY_nvarstack(fs);
+  int i;
+  for (i = 0; i < nvars; i++) {
+    int vidx = fs->nactvar++;
+    Vardesc *var = getlocalvardesc(fs, vidx);
+    var->vd.sidx = stklevel++;
+    var->vd.pidx = registerlocalvar(ls, fs, var->vd.name);
   }
 }
 
 
+/*
+** Close the scope for all variables up to level 'tolevel'.
+** (debug info.)
+*/
 static void removevars (FuncState *fs, int tolevel) {
   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
-  while (fs->nactvar > tolevel)
-    getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
+  while (fs->nactvar > tolevel) {
+    LocVar *var = localdebuginfo(fs, --fs->nactvar);
+    if (var)  /* does it have debug information? */
+      var->endpc = fs->pc;
+  }
 }
 
 
+/*
+** Search the upvalues of the function 'fs' for one
+** with the given 'name'.
+*/
 static int searchupvalue (FuncState *fs, TString *name) {
   int i;
   Upvaldesc *up = fs->f->upvalues;
@@ -225,7 +349,7 @@ static int searchupvalue (FuncState *fs, TString *name) {
 }
 
 
-static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
+static Upvaldesc *allocupvalue (FuncState *fs) {
   Proto *f = fs->f;
   int oldsize = f->sizeupvalues;
   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
@@ -233,58 +357,87 @@ static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
                   Upvaldesc, MAXUPVAL, "upvalues");
   while (oldsize < f->sizeupvalues)
     f->upvalues[oldsize++].name = NULL;
-  f->upvalues[fs->nups].instack = (v->k == VLOCAL);
-  f->upvalues[fs->nups].idx = cast_byte(v->u.info);
-  f->upvalues[fs->nups].name = name;
-  luaC_objbarrier(fs->ls->L, f, name);
-  return fs->nups++;
+  return &f->upvalues[fs->nups++];
 }
 
 
-static int searchvar (FuncState *fs, TString *n) {
+static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
+  Upvaldesc *up = allocupvalue(fs);
+  FuncState *prev = fs->prev;
+  if (v->k == VLOCAL) {
+    up->instack = 1;
+    up->idx = v->u.var.sidx;
+    up->kind = getlocalvardesc(prev, v->u.var.vidx)->vd.kind;
+    lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->vd.name));
+  }
+  else {
+    up->instack = 0;
+    up->idx = cast_byte(v->u.info);
+    up->kind = prev->f->upvalues[v->u.info].kind;
+    lua_assert(eqstr(name, prev->f->upvalues[v->u.info].name));
+  }
+  up->name = name;
+  luaC_objbarrier(fs->ls->L, fs->f, name);
+  return fs->nups - 1;
+}
+
+
+/*
+** Look for an active local variable with the name 'n' in the
+** function 'fs'. If found, initialize 'var' with it and return
+** its expression kind; otherwise return -1.
+*/
+static int searchvar (FuncState *fs, TString *n, expdesc *var) {
   int i;
   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
-    if (eqstr(n, getlocvar(fs, i)->varname))
-      return i;
+    Vardesc *vd = getlocalvardesc(fs, i);
+    if (eqstr(n, vd->vd.name)) {  /* found? */
+      if (vd->vd.kind == RDKCTC)  /* compile-time constant? */
+        init_exp(var, VCONST, fs->firstlocal + i);
+      else  /* real variable */
+        init_var(fs, var, i);
+      return var->k;
+    }
   }
   return -1;  /* not found */
 }
 
 
 /*
-  Mark block where variable at given level was defined
-  (to emit close instructions later).
+** Mark block where variable at given level was defined
+** (to emit close instructions later).
 */
 static void markupval (FuncState *fs, int level) {
   BlockCnt *bl = fs->bl;
   while (bl->nactvar > level)
     bl = bl->previous;
   bl->upval = 1;
+  fs->needclose = 1;
 }
 
 
 /*
-  Find variable with given name 'n'. If it is an upvalue, add this
-  upvalue into all intermediate functions.
+** Find a variable with the given name 'n'. If it is an upvalue, add
+** this upvalue into all intermediate functions. If it is a global, set
+** 'var' as 'void' as a flag.
 */
 static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
   if (fs == NULL)  /* no more levels? */
     init_exp(var, VVOID, 0);  /* default is global */
   else {
-    int v = searchvar(fs, n);  /* look up locals at current level */
+    int v = searchvar(fs, n, var);  /* look up locals at current level */
     if (v >= 0) {  /* found? */
-      init_exp(var, VLOCAL, v);  /* variable is local */
-      if (!base)
-        markupval(fs, v);  /* local will be used as an upval */
+      if (v == VLOCAL && !base)
+        markupval(fs, var->u.var.vidx);  /* local will be used as an upval */
     }
     else {  /* not found as local at current level; try upvalues */
       int idx = searchupvalue(fs, n);  /* try existing upvalues */
       if (idx < 0) {  /* not found? */
         singlevaraux(fs->prev, n, var, 0);  /* try upper levels */
-        if (var->k == VVOID)  /* not found? */
-          return;  /* it is a global */
-        /* else was LOCAL or UPVAL */
-        idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
+        if (var->k == VLOCAL || var->k == VUPVAL)  /* local or upvalue? */
+          idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
+        else  /* it is a global or a constant */
+          return;  /* don't need to do anything at this level */
       }
       init_exp(var, VUPVAL, idx);  /* new or old upvalue */
     }
@@ -292,6 +445,10 @@ static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
 }
 
 
+/*
+** Find a variable with the given name 'n', handling global variables
+** too.
+*/
 static void singlevar (LexState *ls, expdesc *var) {
   TString *varname = str_checkname(ls);
   FuncState *fs = ls->fs;
@@ -300,88 +457,96 @@ static void singlevar (LexState *ls, expdesc *var) {
     expdesc key;
     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
     lua_assert(var->k != VVOID);  /* this one must exist */
-    codestring(ls, &key, varname);  /* key is variable name */
+    codestring(&key, varname);  /* key is variable name */
     luaK_indexed(fs, var, &key);  /* env[varname] */
   }
 }
 
 
+/*
+** Adjust the number of results from an expression list 'e' with 'nexps'
+** expressions to 'nvars' values.
+*/
 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
   FuncState *fs = ls->fs;
-  int extra = nvars - nexps;
-  if (hasmultret(e->k)) {
-    extra++;  /* includes call itself */
-    if (extra < 0) extra = 0;
+  int needed = nvars - nexps;  /* extra values needed */
+  if (hasmultret(e->k)) {  /* last expression has multiple returns? */
+    int extra = needed + 1;  /* discount last expression itself */
+    if (extra < 0)
+      extra = 0;
     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
-    if (extra > 1) luaK_reserveregs(fs, extra-1);
   }
   else {
-    if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
-    if (extra > 0) {
-      int reg = fs->freereg;
-      luaK_reserveregs(fs, extra);
-      luaK_nil(fs, reg, extra);
-    }
+    if (e->k != VVOID)  /* at least one expression? */
+      luaK_exp2nextreg(fs, e);  /* close last expression */
+    if (needed > 0)  /* missing values? */
+      luaK_nil(fs, fs->freereg, needed);  /* complete with nils */
   }
-  if (nexps > nvars)
-    ls->fs->freereg -= nexps - nvars;  /* remove extra values */
+  if (needed > 0)
+    luaK_reserveregs(fs, needed);  /* registers for extra values */
+  else  /* adding 'needed' is actually a subtraction */
+    fs->freereg += needed;  /* remove extra values */
 }
 
 
-static void enterlevel (LexState *ls) {
-  lua_State *L = ls->L;
-  ++L->nCcalls;
-  checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
-}
+/*
+** Macros to limit the maximum recursion depth while parsing
+*/
+#define enterlevel(ls)  luaE_enterCcall((ls)->L)
+
+#define leavelevel(ls)  luaE_exitCcall((ls)->L)
 
 
-#define leavelevel(ls)  ((ls)->L->nCcalls--)
+/*
+** Generates an error that a goto jumps into the scope of some
+** local variable.
+*/
+static l_noret jumpscopeerror (LexState *ls, Labeldesc *gt) {
+  const char *varname = getstr(getlocalvardesc(ls->fs, gt->nactvar)->vd.name);
+  const char *msg = "<goto %s> at line %d jumps into the scope of local '%s'";
+  msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line, varname);
+  luaK_semerror(ls, msg);  /* raise the error */
+}
 
 
-static void closegoto (LexState *ls, int g, Labeldesc *label) {
+/*
+** Solves the goto at index 'g' to given 'label' and removes it
+** from the list of pending goto's.
+** If it jumps into the scope of some variable, raises an error.
+*/
+static void solvegoto (LexState *ls, int g, Labeldesc *label) {
   int i;
-  FuncState *fs = ls->fs;
-  Labellist *gl = &ls->dyd->gt;
-  Labeldesc *gt = &gl->arr[g];
+  Labellist *gl = &ls->dyd->gt;  /* list of goto's */
+  Labeldesc *gt = &gl->arr[g];  /* goto to be resolved */
   lua_assert(eqstr(gt->name, label->name));
-  if (gt->nactvar < label->nactvar) {
-    TString *vname = getlocvar(fs, gt->nactvar)->varname;
-    const char *msg = luaO_pushfstring(ls->L,
-      "<goto %s> at line %d jumps into the scope of local '%s'",
-      getstr(gt->name), gt->line, getstr(vname));
-    semerror(ls, msg);
-  }
-  luaK_patchlist(fs, gt->pc, label->pc);
-  /* remove goto from pending list */
-  for (i = g; i < gl->n - 1; i++)
+  if (unlikely(gt->nactvar < label->nactvar))  /* enter some scope? */
+    jumpscopeerror(ls, gt);
+  luaK_patchlist(ls->fs, gt->pc, label->pc);
+  for (i = g; i < gl->n - 1; i++)  /* remove goto from pending list */
     gl->arr[i] = gl->arr[i + 1];
   gl->n--;
 }
 
 
 /*
-** try to close a goto with existing labels; this solves backward jumps
+** Search for an active label with the given name.
 */
-static int findlabel (LexState *ls, int g) {
+static Labeldesc *findlabel (LexState *ls, TString *name) {
   int i;
-  BlockCnt *bl = ls->fs->bl;
   Dyndata *dyd = ls->dyd;
-  Labeldesc *gt = &dyd->gt.arr[g];
-  /* check labels in current block for a match */
-  for (i = bl->firstlabel; i < dyd->label.n; i++) {
+  /* check labels in current function for a match */
+  for (i = ls->fs->firstlabel; i < dyd->label.n; i++) {
     Labeldesc *lb = &dyd->label.arr[i];
-    if (eqstr(lb->name, gt->name)) {  /* correct label? */
-      if (gt->nactvar > lb->nactvar &&
-          (bl->upval || dyd->label.n > bl->firstlabel))
-        luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
-      closegoto(ls, g, lb);  /* close it */
-      return 1;
-    }
+    if (eqstr(lb->name, name))  /* correct label? */
+      return lb;
   }
-  return 0;  /* label not found; cannot close goto */
+  return NULL;  /* label not found */
 }
 
 
+/*
+** Adds a new label/goto in the corresponding list.
+*/
 static int newlabelentry (LexState *ls, Labellist *l, TString *name,
                           int line, int pc) {
   int n = l->n;
@@ -390,48 +555,76 @@ static int newlabelentry (LexState *ls, Labellist *l, TString *name,
   l->arr[n].name = name;
   l->arr[n].line = line;
   l->arr[n].nactvar = ls->fs->nactvar;
+  l->arr[n].close = 0;
   l->arr[n].pc = pc;
   l->n = n + 1;
   return n;
 }
 
 
+static int newgotoentry (LexState *ls, TString *name, int line, int pc) {
+  return newlabelentry(ls, &ls->dyd->gt, name, line, pc);
+}
+
+
 /*
-** check whether new label 'lb' matches any pending gotos in current
-** block; solves forward jumps
+** Solves forward jumps. Check whether new label 'lb' matches any
+** pending gotos in current block and solves them. Return true
+** if any of the goto's need to close upvalues.
 */
-static void findgotos (LexState *ls, Labeldesc *lb) {
+static int solvegotos (LexState *ls, Labeldesc *lb) {
   Labellist *gl = &ls->dyd->gt;
   int i = ls->fs->bl->firstgoto;
+  int needsclose = 0;
   while (i < gl->n) {
-    if (eqstr(gl->arr[i].name, lb->name))
-      closegoto(ls, i, lb);
+    if (eqstr(gl->arr[i].name, lb->name)) {
+      needsclose |= gl->arr[i].close;
+      solvegoto(ls, i, lb);  /* will remove 'i' from the list */
+    }
     else
       i++;
   }
+  return needsclose;
 }
 
 
 /*
-** export pending gotos to outer level, to check them against
-** outer labels; if the block being exited has upvalues, and
-** the goto exits the scope of any variable (which can be the
-** upvalue), close those variables being exited.
+** Create a new label with the given 'name' at the given 'line'.
+** 'last' tells whether label is the last non-op statement in its
+** block. Solves all pending goto's to this new label and adds
+** a close instruction if necessary.
+** Returns true iff it added a close instruction.
+*/
+static int createlabel (LexState *ls, TString *name, int line,
+                        int last) {
+  FuncState *fs = ls->fs;
+  Labellist *ll = &ls->dyd->label;
+  int l = newlabelentry(ls, ll, name, line, luaK_getlabel(fs));
+  if (last) {  /* label is last no-op statement in the block? */
+    /* assume that locals are already out of scope */
+    ll->arr[l].nactvar = fs->bl->nactvar;
+  }
+  if (solvegotos(ls, &ll->arr[l])) {  /* need close? */
+    luaK_codeABC(fs, OP_CLOSE, luaY_nvarstack(fs), 0, 0);
+    return 1;
+  }
+  return 0;
+}
+
+
+/*
+** Adjust pending gotos to outer level of a block.
 */
 static void movegotosout (FuncState *fs, BlockCnt *bl) {
-  int i = bl->firstgoto;
+  int i;
   Labellist *gl = &fs->ls->dyd->gt;
-  /* correct pending gotos to current block and try to close it
-     with visible labels */
-  while (i < gl->n) {
+  /* correct pending gotos to current block */
+  for (i = bl->firstgoto; i < gl->n; i++) {  /* for each pending goto */
     Labeldesc *gt = &gl->arr[i];
-    if (gt->nactvar > bl->nactvar) {
-      if (bl->upval)
-        luaK_patchclose(fs, gt->pc, bl->nactvar);
-      gt->nactvar = bl->nactvar;
-    }
-    if (!findlabel(fs->ls, i))
-      i++;  /* move to next one */
+    /* leaving a variable scope? */
+    if (stacklevel(fs, gt->nactvar) > stacklevel(fs, bl->nactvar))
+      gt->close |= bl->upval;  /* jump may need a close */
+    gt->nactvar = bl->nactvar;  /* update goto level */
   }
 }
 
@@ -442,54 +635,50 @@ static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
   bl->firstlabel = fs->ls->dyd->label.n;
   bl->firstgoto = fs->ls->dyd->gt.n;
   bl->upval = 0;
+  bl->insidetbc = (fs->bl != NULL && fs->bl->insidetbc);
   bl->previous = fs->bl;
   fs->bl = bl;
-  lua_assert(fs->freereg == fs->nactvar);
+  lua_assert(fs->freereg == luaY_nvarstack(fs));
 }
 
 
 /*
-** create a label named 'break' to resolve break statements
-*/
-static void breaklabel (LexState *ls) {
-  TString *n = luaS_new(ls->L, "break");
-  int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
-  findgotos(ls, &ls->dyd->label.arr[l]);
-}
-
-/*
-** generates an error for an undefined 'goto'; choose appropriate
-** message when label name is a reserved word (which can only be 'break')
+** generates an error for an undefined 'goto'.
 */
 static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
-  const char *msg = isreserved(gt->name)
-                    ? "<%s> at line %d not inside a loop"
-                    : "no visible label '%s' for <goto> at line %d";
-  msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
-  semerror(ls, msg);
+  const char *msg;
+  if (eqstr(gt->name, luaS_newliteral(ls->L, "break"))) {
+    msg = "break outside loop at line %d";
+    msg = luaO_pushfstring(ls->L, msg, gt->line);
+  }
+  else {
+    msg = "no visible label '%s' for <goto> at line %d";
+    msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
+  }
+  luaK_semerror(ls, msg);
 }
 
 
 static void leaveblock (FuncState *fs) {
   BlockCnt *bl = fs->bl;
   LexState *ls = fs->ls;
-  if (bl->previous && bl->upval) {
-    /* create a 'jump to here' to close upvalues */
-    int j = luaK_jump(fs);
-    luaK_patchclose(fs, j, bl->nactvar);
-    luaK_patchtohere(fs, j);
-  }
-  if (bl->isloop)
-    breaklabel(ls);  /* close pending breaks */
+  int hasclose = 0;
+  int stklevel = stacklevel(fs, bl->nactvar);  /* level outside the block */
+  if (bl->isloop)  /* fix pending breaks? */
+    hasclose = createlabel(ls, luaS_newliteral(ls->L, "break"), 0, 0);
+  if (!hasclose && bl->previous && bl->upval)
+    luaK_codeABC(fs, OP_CLOSE, stklevel, 0, 0);
   fs->bl = bl->previous;
   removevars(fs, bl->nactvar);
   lua_assert(bl->nactvar == fs->nactvar);
-  fs->freereg = fs->nactvar;  /* free registers */
+  fs->freereg = stklevel;  /* free registers */
   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
   if (bl->previous)  /* inner block? */
     movegotosout(fs, bl);  /* update pending gotos to outer block */
-  else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
-    undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
+  else {
+    if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
+      undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
+  }
 }
 
 
@@ -515,35 +704,40 @@ static Proto *addprototype (LexState *ls) {
 
 /*
 ** codes instruction to create new closure in parent function.
-** The OP_CLOSURE instruction must use the last available register,
+** The OP_CLOSURE instruction uses the last available register,
 ** so that, if it invokes the GC, the GC knows which registers
 ** are in use at that time.
+
 */
 static void codeclosure (LexState *ls, expdesc *v) {
   FuncState *fs = ls->fs->prev;
-  init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
+  init_exp(v, VRELOC, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
 }
 
 
 static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
-  Proto *f;
+  Proto *f = fs->f;
   fs->prev = ls->fs;  /* linked list of funcstates */
   fs->ls = ls;
   ls->fs = fs;
   fs->pc = 0;
+  fs->previousline = f->linedefined;
+  fs->iwthabs = 0;
   fs->lasttarget = 0;
-  fs->jpc = NO_JUMP;
   fs->freereg = 0;
   fs->nk = 0;
+  fs->nabslineinfo = 0;
   fs->np = 0;
   fs->nups = 0;
-  fs->nlocvars = 0;
+  fs->ndebugvars = 0;
   fs->nactvar = 0;
+  fs->needclose = 0;
   fs->firstlocal = ls->dyd->actvar.n;
+  fs->firstlabel = ls->dyd->label.n;
   fs->bl = NULL;
-  f = fs->f;
   f->source = ls->source;
+  luaC_objbarrier(ls->L, f, f->source);
   f->maxstacksize = 2;  /* registers 0/1 are always valid */
   enterblock(fs, bl, 0);
 }
@@ -553,21 +747,18 @@ static void close_func (LexState *ls) {
   lua_State *L = ls->L;
   FuncState *fs = ls->fs;
   Proto *f = fs->f;
-  luaK_ret(fs, 0, 0);  /* final return */
+  luaK_ret(fs, luaY_nvarstack(fs), 0);  /* final return */
   leaveblock(fs);
-  luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
-  f->sizecode = fs->pc;
-  luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
-  f->sizelineinfo = fs->pc;
-  luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
-  f->sizek = fs->nk;
-  luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
-  f->sizep = fs->np;
-  luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
-  f->sizelocvars = fs->nlocvars;
-  luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
-  f->sizeupvalues = fs->nups;
   lua_assert(fs->bl == NULL);
+  luaK_finish(fs);
+  luaM_shrinkvector(L, f->code, f->sizecode, fs->pc, Instruction);
+  luaM_shrinkvector(L, f->lineinfo, f->sizelineinfo, fs->pc, ls_byte);
+  luaM_shrinkvector(L, f->abslineinfo, f->sizeabslineinfo,
+                       fs->nabslineinfo, AbsLineInfo);
+  luaM_shrinkvector(L, f->k, f->sizek, fs->nk, TValue);
+  luaM_shrinkvector(L, f->p, f->sizep, fs->np, Proto *);
+  luaM_shrinkvector(L, f->locvars, f->sizelocvars, fs->ndebugvars, LocVar);
+  luaM_shrinkvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
   ls->fs = fs->prev;
   luaC_checkGC(L);
 }
@@ -613,7 +804,7 @@ static void fieldsel (LexState *ls, expdesc *v) {
   expdesc key;
   luaK_exp2anyregup(fs, v);
   luaX_next(ls);  /* skip the dot or colon */
-  checkname(ls, &key);
+  codename(ls, &key);
   luaK_indexed(fs, v, &key);
 }
 
@@ -634,48 +825,49 @@ static void yindex (LexState *ls, expdesc *v) {
 */
 
 
-struct ConsControl {
+typedef struct ConsControl {
   expdesc v;  /* last list item read */
   expdesc *t;  /* table descriptor */
   int nh;  /* total number of 'record' elements */
-  int na;  /* total number of array elements */
+  int na;  /* number of array elements already stored */
   int tostore;  /* number of array elements pending to be stored */
-};
+} ConsControl;
 
 
-static void recfield (LexState *ls, struct ConsControl *cc) {
-  /* recfield -> (NAME | '['exp1']') = exp1 */
+static void recfield (LexState *ls, ConsControl *cc) {
+  /* recfield -> (NAME | '['exp']') = exp */
   FuncState *fs = ls->fs;
   int reg = ls->fs->freereg;
-  expdesc key, val;
-  int rkkey;
+  expdesc tab, key, val;
   if (ls->t.token == TK_NAME) {
     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
-    checkname(ls, &key);
+    codename(ls, &key);
   }
   else  /* ls->t.token == '[' */
     yindex(ls, &key);
   cc->nh++;
   checknext(ls, '=');
-  rkkey = luaK_exp2RK(fs, &key);
+  tab = *cc->t;
+  luaK_indexed(fs, &tab, &key);
   expr(ls, &val);
-  luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
+  luaK_storevar(fs, &tab, &val);
   fs->freereg = reg;  /* free registers */
 }
 
 
-static void closelistfield (FuncState *fs, struct ConsControl *cc) {
+static void closelistfield (FuncState *fs, ConsControl *cc) {
   if (cc->v.k == VVOID) return;  /* there is no list item */
   luaK_exp2nextreg(fs, &cc->v);
   cc->v.k = VVOID;
   if (cc->tostore == LFIELDS_PER_FLUSH) {
     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
+    cc->na += cc->tostore;
     cc->tostore = 0;  /* no more items pending */
   }
 }
 
 
-static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
+static void lastlistfield (FuncState *fs, ConsControl *cc) {
   if (cc->tostore == 0) return;
   if (hasmultret(cc->v.k)) {
     luaK_setmultret(fs, &cc->v);
@@ -687,19 +879,18 @@ static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
       luaK_exp2nextreg(fs, &cc->v);
     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
   }
+  cc->na += cc->tostore;
 }
 
 
-static void listfield (LexState *ls, struct ConsControl *cc) {
+static void listfield (LexState *ls, ConsControl *cc) {
   /* listfield -> exp */
   expr(ls, &cc->v);
-  checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
-  cc->na++;
   cc->tostore++;
 }
 
 
-static void field (LexState *ls, struct ConsControl *cc) {
+static void field (LexState *ls, ConsControl *cc) {
   /* field -> listfield | recfield */
   switch(ls->t.token) {
     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
@@ -727,12 +918,13 @@ static void constructor (LexState *ls, expdesc *t) {
   FuncState *fs = ls->fs;
   int line = ls->linenumber;
   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
-  struct ConsControl cc;
+  ConsControl cc;
+  luaK_code(fs, 0);  /* space for extra arg. */
   cc.na = cc.nh = cc.tostore = 0;
   cc.t = t;
-  init_exp(t, VRELOCABLE, pc);
+  init_exp(t, VNONRELOC, fs->freereg);  /* table will be at stack top */
+  luaK_reserveregs(fs, 1);
   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
-  luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
   checknext(ls, '{');
   do {
     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
@@ -742,20 +934,24 @@ static void constructor (LexState *ls, expdesc *t) {
   } while (testnext(ls, ',') || testnext(ls, ';'));
   check_match(ls, '}', '{', line);
   lastlistfield(fs, &cc);
-  SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
-  SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
+  luaK_settablesize(fs, pc, t->u.info, cc.na, cc.nh);
 }
 
 /* }====================================================================== */
 
 
+static void setvararg (FuncState *fs, int nparams) {
+  fs->f->is_vararg = 1;
+  luaK_codeABC(fs, OP_VARARGPREP, nparams, 0, 0);
+}
+
 
 static void parlist (LexState *ls) {
   /* parlist -> [ param { ',' param } ] */
   FuncState *fs = ls->fs;
   Proto *f = fs->f;
   int nparams = 0;
-  f->is_vararg = 0;
+  int isvararg = 0;
   if (ls->t.token != ')') {  /* is 'parlist' not empty? */
     do {
       switch (ls->t.token) {
@@ -766,16 +962,18 @@ static void parlist (LexState *ls) {
         }
         case TK_DOTS: {  /* param -> '...' */
           luaX_next(ls);
-          f->is_vararg = 1;  /* declared vararg */
+          isvararg = 1;
           break;
         }
         default: luaX_syntaxerror(ls, "<name> or '...' expected");
       }
-    } while (!f->is_vararg && testnext(ls, ','));
+    } while (!isvararg && testnext(ls, ','));
   }
   adjustlocalvars(ls, nparams);
   f->numparams = cast_byte(fs->nactvar);
-  luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
+  if (isvararg)
+    setvararg(fs, f->numparams);  /* declared vararg */
+  luaK_reserveregs(fs, fs->nactvar);  /* reserve registers for parameters */
 }
 
 
@@ -825,7 +1023,8 @@ static void funcargs (LexState *ls, expdesc *f, int line) {
         args.k = VVOID;
       else {
         explist(ls, &args);
-        luaK_setmultret(fs, &args);
+        if (hasmultret(args.k))
+          luaK_setmultret(fs, &args);
       }
       check_match(ls, ')', '(', line);
       break;
@@ -835,7 +1034,7 @@ static void funcargs (LexState *ls, expdesc *f, int line) {
       break;
     }
     case TK_STRING: {  /* funcargs -> STRING */
-      codestring(ls, &args, ls->t.seminfo.ts);
+      codestring(&args, ls->t.seminfo.ts);
       luaX_next(ls);  /* must use 'seminfo' before 'next' */
       break;
     }
@@ -902,7 +1101,7 @@ static void suffixedexp (LexState *ls, expdesc *v) {
         fieldsel(ls, v);
         break;
       }
-      case '[': {  /* '[' exp1 ']' */
+      case '[': {  /* '[' exp ']' */
         expdesc key;
         luaK_exp2anyregup(fs, v);
         yindex(ls, &key);
@@ -912,7 +1111,7 @@ static void suffixedexp (LexState *ls, expdesc *v) {
       case ':': {  /* ':' NAME funcargs */
         expdesc key;
         luaX_next(ls);
-        checkname(ls, &key);
+        codename(ls, &key);
         luaK_self(fs, v, &key);
         funcargs(ls, v, line);
         break;
@@ -943,7 +1142,7 @@ static void simpleexp (LexState *ls, expdesc *v) {
       break;
     }
     case TK_STRING: {
-      codestring(ls, v, ls->t.seminfo.ts);
+      codestring(v, ls->t.seminfo.ts);
       break;
     }
     case TK_NIL: {
@@ -962,7 +1161,7 @@ static void simpleexp (LexState *ls, expdesc *v) {
       FuncState *fs = ls->fs;
       check_condition(ls, fs->f->is_vararg,
                       "cannot use '...' outside a vararg function");
-      init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
+      init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 0, 1));
       break;
     }
     case '{': {  /* constructor */
@@ -1022,6 +1221,9 @@ static BinOpr getbinopr (int op) {
 }
 
 
+/*
+** Priority table for binary operators.
+*/
 static const struct {
   lu_byte left;  /* left priority for each binary operator */
   lu_byte right; /* right priority */
@@ -1050,9 +1252,9 @@ static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
   UnOpr uop;
   enterlevel(ls);
   uop = getunopr(ls->t.token);
-  if (uop != OPR_NOUNOPR) {
+  if (uop != OPR_NOUNOPR) {  /* prefix (unary) operator? */
     int line = ls->linenumber;
-    luaX_next(ls);
+    luaX_next(ls);  /* skip operator */
     subexpr(ls, v, UNARY_PRIORITY);
     luaK_prefix(ls->fs, uop, v, line);
   }
@@ -1063,7 +1265,7 @@ static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
     expdesc v2;
     BinOpr nextop;
     int line = ls->linenumber;
-    luaX_next(ls);
+    luaX_next(ls);  /* skip operator */
     luaK_infix(ls->fs, op, v);
     /* read sub-expression with higher priority */
     nextop = subexpr(ls, &v2, priority[op].right);
@@ -1121,43 +1323,60 @@ static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
   int extra = fs->freereg;  /* eventual position to save local variable */
   int conflict = 0;
   for (; lh; lh = lh->prev) {  /* check all previous assignments */
-    if (lh->v.k == VINDEXED) {  /* assigning to a table? */
-      /* table is the upvalue/local being assigned now? */
-      if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
-        conflict = 1;
-        lh->v.u.ind.vt = VLOCAL;
-        lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
+    if (vkisindexed(lh->v.k)) {  /* assignment to table field? */
+      if (lh->v.k == VINDEXUP) {  /* is table an upvalue? */
+        if (v->k == VUPVAL && lh->v.u.ind.t == v->u.info) {
+          conflict = 1;  /* table is the upvalue being assigned now */
+          lh->v.k = VINDEXSTR;
+          lh->v.u.ind.t = extra;  /* assignment will use safe copy */
+        }
       }
-      /* index is the local being assigned? (index cannot be upvalue) */
-      if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
-        conflict = 1;
-        lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
+      else {  /* table is a register */
+        if (v->k == VLOCAL && lh->v.u.ind.t == v->u.var.sidx) {
+          conflict = 1;  /* table is the local being assigned now */
+          lh->v.u.ind.t = extra;  /* assignment will use safe copy */
+        }
+        /* is index the local being assigned? */
+        if (lh->v.k == VINDEXED && v->k == VLOCAL &&
+            lh->v.u.ind.idx == v->u.var.sidx) {
+          conflict = 1;
+          lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
+        }
       }
     }
   }
   if (conflict) {
     /* copy upvalue/local value to a temporary (in position 'extra') */
-    OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
-    luaK_codeABC(fs, op, extra, v->u.info, 0);
+    if (v->k == VLOCAL)
+      luaK_codeABC(fs, OP_MOVE, extra, v->u.var.sidx, 0);
+    else
+      luaK_codeABC(fs, OP_GETUPVAL, extra, v->u.info, 0);
     luaK_reserveregs(fs, 1);
   }
 }
 
-
-static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
+/*
+** Parse and compile a multiple assignment. The first "variable"
+** (a 'suffixedexp') was already read by the caller.
+**
+** assignment -> suffixedexp restassign
+** restassign -> ',' suffixedexp restassign | '=' explist
+*/
+static void restassign (LexState *ls, struct LHS_assign *lh, int nvars) {
   expdesc e;
   check_condition(ls, vkisvar(lh->v.k), "syntax error");
-  if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
+  check_readonly(ls, &lh->v);
+  if (testnext(ls, ',')) {  /* restassign -> ',' suffixedexp restassign */
     struct LHS_assign nv;
     nv.prev = lh;
     suffixedexp(ls, &nv.v);
-    if (nv.v.k != VINDEXED)
+    if (!vkisindexed(nv.v.k))
       check_conflict(ls, lh, &nv.v);
-    checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
-                    "C levels");
-    assignment(ls, &nv, nvars+1);
+    enterlevel(ls);  /* control recursion depth */
+    restassign(ls, &nv, nvars+1);
+    leavelevel(ls);
   }
-  else {  /* assignment -> '=' explist */
+  else {  /* restassign -> '=' explist */
     int nexps;
     checknext(ls, '=');
     nexps = explist(ls, &e);
@@ -1184,57 +1403,55 @@ static int cond (LexState *ls) {
 }
 
 
-static void gotostat (LexState *ls, int pc) {
+static void gotostat (LexState *ls) {
+  FuncState *fs = ls->fs;
   int line = ls->linenumber;
-  TString *label;
-  int g;
-  if (testnext(ls, TK_GOTO))
-    label = str_checkname(ls);
-  else {
-    luaX_next(ls);  /* skip break */
-    label = luaS_new(ls->L, "break");
+  TString *name = str_checkname(ls);  /* label's name */
+  Labeldesc *lb = findlabel(ls, name);
+  if (lb == NULL)  /* no label? */
+    /* forward jump; will be resolved when the label is declared */
+    newgotoentry(ls, name, line, luaK_jump(fs));
+  else {  /* found a label */
+    /* backward jump; will be resolved here */
+    int lblevel = stacklevel(fs, lb->nactvar);  /* label level */
+    if (luaY_nvarstack(fs) > lblevel)  /* leaving the scope of a variable? */
+      luaK_codeABC(fs, OP_CLOSE, lblevel, 0, 0);
+    /* create jump and link it to the label */
+    luaK_patchlist(fs, luaK_jump(fs), lb->pc);
   }
-  g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
-  findlabel(ls, g);  /* close it if label already defined */
 }
 
 
-/* check for repeated labels on the same block */
-static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
-  int i;
-  for (i = fs->bl->firstlabel; i < ll->n; i++) {
-    if (eqstr(label, ll->arr[i].name)) {
-      const char *msg = luaO_pushfstring(fs->ls->L,
-                          "label '%s' already defined on line %d",
-                          getstr(label), ll->arr[i].line);
-      semerror(fs->ls, msg);
-    }
-  }
+/*
+** Break statement. Semantically equivalent to "goto break".
+*/
+static void breakstat (LexState *ls) {
+  int line = ls->linenumber;
+  luaX_next(ls);  /* skip break */
+  newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, luaK_jump(ls->fs));
 }
 
 
-/* skip no-op statements */
-static void skipnoopstat (LexState *ls) {
-  while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
-    statement(ls);
+/*
+** Check whether there is already a label with the given 'name'.
+*/
+static void checkrepeated (LexState *ls, TString *name) {
+  Labeldesc *lb = findlabel(ls, name);
+  if (unlikely(lb != NULL)) {  /* already defined? */
+    const char *msg = "label '%s' already defined on line %d";
+    msg = luaO_pushfstring(ls->L, msg, getstr(name), lb->line);
+    luaK_semerror(ls, msg);  /* error */
+  }
 }
 
 
-static void labelstat (LexState *ls, TString *label, int line) {
+static void labelstat (LexState *ls, TString *name, int line) {
   /* label -> '::' NAME '::' */
-  FuncState *fs = ls->fs;
-  Labellist *ll = &ls->dyd->label;
-  int l;  /* index of new label being created */
-  checkrepeated(fs, ll, label);  /* check for repeated labels */
   checknext(ls, TK_DBCOLON);  /* skip double colon */
-  /* create new entry for this label */
-  l = newlabelentry(ls, ll, label, line, luaK_getlabel(fs));
-  skipnoopstat(ls);  /* skip other no-op statements */
-  if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
-    /* assume that locals are already out of scope */
-    ll->arr[l].nactvar = fs->bl->nactvar;
-  }
-  findgotos(ls, &ll->arr[l]);
+  while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
+    statement(ls);  /* skip other no-op statements */
+  checkrepeated(ls, name);  /* check for repeated labels */
+  createlabel(ls, name, line, block_follow(ls, 0));
 }
 
 
@@ -1269,58 +1486,83 @@ static void repeatstat (LexState *ls, int line) {
   statlist(ls);
   check_match(ls, TK_UNTIL, TK_REPEAT, line);
   condexit = cond(ls);  /* read condition (inside scope block) */
-  if (bl2.upval)  /* upvalues? */
-    luaK_patchclose(fs, condexit, bl2.nactvar);
   leaveblock(fs);  /* finish scope */
+  if (bl2.upval) {  /* upvalues? */
+    int exit = luaK_jump(fs);  /* normal exit must jump over fix */
+    luaK_patchtohere(fs, condexit);  /* repetition must close upvalues */
+    luaK_codeABC(fs, OP_CLOSE, stacklevel(fs, bl2.nactvar), 0, 0);
+    condexit = luaK_jump(fs);  /* repeat after closing upvalues */
+    luaK_patchtohere(fs, exit);  /* normal exit comes to here */
+  }
   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
   leaveblock(fs);  /* finish loop */
 }
 
 
-static int exp1 (LexState *ls) {
+/*
+** Read an expression and generate code to put its results in next
+** stack slot.
+**
+*/
+static void exp1 (LexState *ls) {
   expdesc e;
-  int reg;
   expr(ls, &e);
   luaK_exp2nextreg(ls->fs, &e);
   lua_assert(e.k == VNONRELOC);
-  reg = e.u.info;
-  return reg;
 }
 
 
-static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
+/*
+** Fix for instruction at position 'pc' to jump to 'dest'.
+** (Jump addresses are relative in Lua). 'back' true means
+** a back jump.
+*/
+static void fixforjump (FuncState *fs, int pc, int dest, int back) {
+  Instruction *jmp = &fs->f->code[pc];
+  int offset = dest - (pc + 1);
+  if (back)
+    offset = -offset;
+  if (unlikely(offset > MAXARG_Bx))
+    luaX_syntaxerror(fs->ls, "control structure too long");
+  SETARG_Bx(*jmp, offset);
+}
+
+
+/*
+** Generate code for a 'for' loop.
+*/
+static void forbody (LexState *ls, int base, int line, int nvars, int isgen) {
   /* forbody -> DO block */
+  static const OpCode forprep[2] = {OP_FORPREP, OP_TFORPREP};
+  static const OpCode forloop[2] = {OP_FORLOOP, OP_TFORLOOP};
   BlockCnt bl;
   FuncState *fs = ls->fs;
   int prep, endfor;
-  adjustlocalvars(ls, 3);  /* control variables */
   checknext(ls, TK_DO);
-  prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
+  prep = luaK_codeABx(fs, forprep[isgen], base, 0);
   enterblock(fs, &bl, 0);  /* scope for declared variables */
   adjustlocalvars(ls, nvars);
   luaK_reserveregs(fs, nvars);
   block(ls);
   leaveblock(fs);  /* end of scope for declared variables */
-  luaK_patchtohere(fs, prep);
-  if (isnum)  /* numeric for? */
-    endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
-  else {  /* generic for */
+  fixforjump(fs, prep, luaK_getlabel(fs), 0);
+  if (isgen) {  /* generic for? */
     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
     luaK_fixline(fs, line);
-    endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
   }
-  luaK_patchlist(fs, endfor, prep + 1);
+  endfor = luaK_codeABx(fs, forloop[isgen], base, 0);
+  fixforjump(fs, endfor, prep + 1, 1);
   luaK_fixline(fs, line);
 }
 
 
 static void fornum (LexState *ls, TString *varname, int line) {
-  /* fornum -> NAME = exp1,exp1[,exp1] forbody */
+  /* fornum -> NAME = exp,exp[,exp] forbody */
   FuncState *fs = ls->fs;
   int base = fs->freereg;
-  new_localvarliteral(ls, "(for index)");
-  new_localvarliteral(ls, "(for limit)");
-  new_localvarliteral(ls, "(for step)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
   new_localvar(ls, varname);
   checknext(ls, '=');
   exp1(ls);  /* initial value */
@@ -1329,10 +1571,11 @@ static void fornum (LexState *ls, TString *varname, int line) {
   if (testnext(ls, ','))
     exp1(ls);  /* optional step */
   else {  /* default step = 1 */
-    luaK_codek(fs, fs->freereg, luaK_intK(fs, 1));
+    luaK_int(fs, fs->freereg, 1);
     luaK_reserveregs(fs, 1);
   }
-  forbody(ls, base, line, 1, 1);
+  adjustlocalvars(ls, 3);  /* control variables */
+  forbody(ls, base, line, 1, 0);
 }
 
 
@@ -1340,13 +1583,14 @@ static void forlist (LexState *ls, TString *indexname) {
   /* forlist -> NAME {,NAME} IN explist forbody */
   FuncState *fs = ls->fs;
   expdesc e;
-  int nvars = 4;  /* gen, state, control, plus at least one declared var */
+  int nvars = 5;  /* gen, state, control, toclose, 'indexname' */
   int line;
   int base = fs->freereg;
   /* create control variables */
-  new_localvarliteral(ls, "(for generator)");
   new_localvarliteral(ls, "(for state)");
-  new_localvarliteral(ls, "(for control)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
   /* create declared variables */
   new_localvar(ls, indexname);
   while (testnext(ls, ',')) {
@@ -1355,9 +1599,11 @@ static void forlist (LexState *ls, TString *indexname) {
   }
   checknext(ls, TK_IN);
   line = ls->linenumber;
-  adjust_assign(ls, 3, explist(ls, &e), &e);
+  adjust_assign(ls, 4, explist(ls, &e), &e);
+  adjustlocalvars(ls, 4);  /* control variables */
+  markupval(fs, fs->nactvar);  /* last control var. must be closed */
   luaK_checkstack(fs, 3);  /* extra space to call generator */
-  forbody(ls, base, line, nvars - 3, 0);
+  forbody(ls, base, line, nvars - 4, 1);
 }
 
 
@@ -1379,28 +1625,68 @@ static void forstat (LexState *ls, int line) {
 }
 
 
+/*
+** Check whether next instruction is a single jump (a 'break', a 'goto'
+** to a forward label, or a 'goto' to a backward label with no variable
+** to close). If so, set the name of the 'label' it is jumping to
+** ("break" for a 'break') or to where it is jumping to ('target') and
+** return true. If not a single jump, leave input unchanged, to be
+** handled as a regular statement.
+*/
+static int issinglejump (LexState *ls, TString **label, int *target) {
+  if (testnext(ls, TK_BREAK)) {  /* a break? */
+    *label = luaS_newliteral(ls->L, "break");
+    return 1;
+  }
+  else if (ls->t.token != TK_GOTO || luaX_lookahead(ls) != TK_NAME)
+    return 0;  /* not a valid goto */
+  else {
+    TString *lname = ls->lookahead.seminfo.ts;  /* label's id */
+    Labeldesc *lb = findlabel(ls, lname);
+    if (lb) {  /* a backward jump? */
+      /* does it need to close variables? */
+      if (luaY_nvarstack(ls->fs) > stacklevel(ls->fs, lb->nactvar))
+        return 0;  /* not a single jump; cannot optimize */
+      *target = lb->pc;
+    }
+    else  /* jump forward */
+      *label = lname;
+    luaX_next(ls);  /* skip goto */
+    luaX_next(ls);  /* skip name */
+    return 1;
+  }
+}
+
+
 static void test_then_block (LexState *ls, int *escapelist) {
   /* test_then_block -> [IF | ELSEIF] cond THEN block */
   BlockCnt bl;
+  int line;
   FuncState *fs = ls->fs;
+  TString *jlb = NULL;
+  int target = NO_JUMP;
   expdesc v;
   int jf;  /* instruction to skip 'then' code (if condition is false) */
   luaX_next(ls);  /* skip IF or ELSEIF */
   expr(ls, &v);  /* read condition */
   checknext(ls, TK_THEN);
-  if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
+  line = ls->linenumber;
+  if (issinglejump(ls, &jlb, &target)) {  /* 'if x then goto' ? */
     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
-    gotostat(ls, v.t);  /* handle goto/break */
-    while (testnext(ls, ';')) {}  /* skip colons */
-    if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
+    if (jlb != NULL)  /* forward jump? */
+      newgotoentry(ls, jlb, line, v.t);  /* will be resolved later */
+    else  /* backward jump */
+      luaK_patchlist(fs, v.t, target);  /* jump directly to 'target' */
+    while (testnext(ls, ';')) {}  /* skip semicolons */
+    if (block_follow(ls, 0)) {  /* jump is the entire block? */
       leaveblock(fs);
       return;  /* and that is it */
     }
     else  /* must skip over 'then' part if condition is false */
       jf = luaK_jump(fs);
   }
-  else {  /* regular case (not goto/break) */
+  else {  /* regular case (not a jump) */
     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
     enterblock(fs, &bl, 0);
     jf = v.f;
@@ -1431,21 +1717,60 @@ static void ifstat (LexState *ls, int line) {
 static void localfunc (LexState *ls) {
   expdesc b;
   FuncState *fs = ls->fs;
+  int fvar = fs->nactvar;  /* function's variable index */
   new_localvar(ls, str_checkname(ls));  /* new local variable */
   adjustlocalvars(ls, 1);  /* enter its scope */
   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
   /* debug information will only see the variable after this point! */
-  getlocvar(fs, b.u.info)->startpc = fs->pc;
+  localdebuginfo(fs, fvar)->startpc = fs->pc;
+}
+
+
+static int getlocalattribute (LexState *ls) {
+  /* ATTRIB -> ['<' Name '>'] */
+  if (testnext(ls, '<')) {
+    const char *attr = getstr(str_checkname(ls));
+    checknext(ls, '>');
+    if (strcmp(attr, "const") == 0)
+      return RDKCONST;  /* read-only variable */
+    else if (strcmp(attr, "close") == 0)
+      return RDKTOCLOSE;  /* to-be-closed variable */
+    else
+      luaK_semerror(ls,
+        luaO_pushfstring(ls->L, "unknown attribute '%s'", attr));
+  }
+  return VDKREG;  /* regular variable */
+}
+
+
+static void checktoclose (LexState *ls, int level) {
+  if (level != -1) {  /* is there a to-be-closed variable? */
+    FuncState *fs = ls->fs;
+    markupval(fs, level + 1);
+    fs->bl->insidetbc = 1;  /* in the scope of a to-be-closed variable */
+    luaK_codeABC(fs, OP_TBC, stacklevel(fs, level), 0, 0);
+  }
 }
 
 
 static void localstat (LexState *ls) {
-  /* stat -> LOCAL NAME {',' NAME} ['=' explist] */
+  /* stat -> LOCAL ATTRIB NAME {',' ATTRIB NAME} ['=' explist] */
+  FuncState *fs = ls->fs;
+  int toclose = -1;  /* index of to-be-closed variable (if any) */
+  Vardesc *var;  /* last variable */
+  int vidx, kind;  /* index and kind of last variable */
   int nvars = 0;
   int nexps;
   expdesc e;
   do {
-    new_localvar(ls, str_checkname(ls));
+    vidx = new_localvar(ls, str_checkname(ls));
+    kind = getlocalattribute(ls);
+    getlocalvardesc(fs, vidx)->vd.kind = kind;
+    if (kind == RDKTOCLOSE) {  /* to-be-closed? */
+      if (toclose != -1)  /* one already present? */
+        luaK_semerror(ls, "multiple to-be-closed variables in local list");
+      toclose = fs->nactvar + nvars;
+    }
     nvars++;
   } while (testnext(ls, ','));
   if (testnext(ls, '='))
@@ -1454,8 +1779,19 @@ static void localstat (LexState *ls) {
     e.k = VVOID;
     nexps = 0;
   }
-  adjust_assign(ls, nvars, nexps, &e);
-  adjustlocalvars(ls, nvars);
+  var = getlocalvardesc(fs, vidx);  /* get last variable */
+  if (nvars == nexps &&  /* no adjustments? */
+      var->vd.kind == RDKCONST &&  /* last variable is const? */
+      luaK_exp2const(fs, &e, &var->k)) {  /* compile-time constant? */
+    var->vd.kind = RDKCTC;  /* variable is a compile-time constant */
+    adjustlocalvars(ls, nvars - 1);  /* exclude last variable */
+    fs->nactvar++;  /* but count it */
+  }
+  else {
+    adjust_assign(ls, nvars, nexps, &e);
+    adjustlocalvars(ls, nvars);
+  }
+  checktoclose(ls, toclose);
 }
 
 
@@ -1492,11 +1828,13 @@ static void exprstat (LexState *ls) {
   suffixedexp(ls, &v.v);
   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
     v.prev = NULL;
-    assignment(ls, &v, 1);
+    restassign(ls, &v, 1);
   }
   else {  /* stat -> func */
+    Instruction *inst;
     check_condition(ls, v.v.k == VCALL, "syntax error");
-    SETARG_C(getinstruction(fs, &v.v), 1);  /* call statement uses no results */
+    inst = &getinstruction(fs, &v.v);
+    SETARG_C(*inst, 1);  /* call statement uses no results */
   }
 }
 
@@ -1505,26 +1843,25 @@ static void retstat (LexState *ls) {
   /* stat -> RETURN [explist] [';'] */
   FuncState *fs = ls->fs;
   expdesc e;
-  int first, nret;  /* registers with returned values */
+  int nret;  /* number of values being returned */
+  int first = luaY_nvarstack(fs);  /* first slot to be returned */
   if (block_follow(ls, 1) || ls->t.token == ';')
-    first = nret = 0;  /* return no values */
+    nret = 0;  /* return no values */
   else {
     nret = explist(ls, &e);  /* optional return values */
     if (hasmultret(e.k)) {
       luaK_setmultret(fs, &e);
-      if (e.k == VCALL && nret == 1) {  /* tail call? */
+      if (e.k == VCALL && nret == 1 && !fs->bl->insidetbc) {  /* tail call? */
         SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
-        lua_assert(GETARG_A(getinstruction(fs,&e)) == fs->nactvar);
+        lua_assert(GETARG_A(getinstruction(fs,&e)) == luaY_nvarstack(fs));
       }
-      first = fs->nactvar;
       nret = LUA_MULTRET;  /* return all values */
     }
     else {
       if (nret == 1)  /* only one single value? */
-        first = luaK_exp2anyreg(fs, &e);
-      else {
-        luaK_exp2nextreg(fs, &e);  /* values must go to the stack */
-        first = fs->nactvar;  /* return all active values */
+        first = luaK_exp2anyreg(fs, &e);  /* can use original slot */
+      else {  /* values must go to the top of the stack */
+        luaK_exp2nextreg(fs, &e);
         lua_assert(nret == fs->freereg - first);
       }
     }
@@ -1586,9 +1923,13 @@ static void statement (LexState *ls) {
       retstat(ls);
       break;
     }
-    case TK_BREAK:   /* stat -> breakstat */
+    case TK_BREAK: {  /* stat -> breakstat */
+      breakstat(ls);
+      break;
+    }
     case TK_GOTO: {  /* stat -> 'goto' NAME */
-      gotostat(ls, luaK_jump(ls->fs));
+      luaX_next(ls);  /* skip 'goto' */
+      gotostat(ls);
       break;
     }
     default: {  /* stat -> func | assignment */
@@ -1597,8 +1938,8 @@ static void statement (LexState *ls) {
     }
   }
   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
-             ls->fs->freereg >= ls->fs->nactvar);
-  ls->fs->freereg = ls->fs->nactvar;  /* free registers */
+             ls->fs->freereg >= luaY_nvarstack(ls->fs));
+  ls->fs->freereg = luaY_nvarstack(ls->fs);  /* free registers */
   leavelevel(ls);
 }
 
@@ -1611,11 +1952,15 @@ static void statement (LexState *ls) {
 */
 static void mainfunc (LexState *ls, FuncState *fs) {
   BlockCnt bl;
-  expdesc v;
+  Upvaldesc *env;
   open_func(ls, fs, &bl);
-  fs->f->is_vararg = 1;  /* main function is always declared vararg */
-  init_exp(&v, VLOCAL, 0);  /* create and... */
-  newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
+  setvararg(fs, 0);  /* main function is always declared vararg */
+  env = allocupvalue(fs);  /* ...set environment upvalue */
+  env->instack = 1;
+  env->idx = 0;
+  env->kind = VDKREG;
+  env->name = ls->envn;
+  luaC_objbarrier(ls->L, fs->f, env->name);
   luaX_next(ls);  /* read first token */
   statlist(ls);  /* parse main body */
   check(ls, TK_EOS);
@@ -1628,14 +1973,15 @@ LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
   LexState lexstate;
   FuncState funcstate;
   LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
-  setclLvalue(L, L->top, cl);  /* anchor it (to avoid being collected) */
+  setclLvalue2s(L, L->top, cl);  /* anchor it (to avoid being collected) */
   luaD_inctop(L);
   lexstate.h = luaH_new(L);  /* create table for scanner */
-  sethvalue(L, L->top, lexstate.h);  /* anchor it */
+  sethvalue2s(L, L->top, lexstate.h);  /* anchor it */
   luaD_inctop(L);
   funcstate.f = cl->p = luaF_newproto(L);
+  luaC_objbarrier(L, cl, cl->p);
   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
-  lua_assert(iswhite(funcstate.f));  /* do not need barrier here */
+  luaC_objbarrier(L, funcstate.f, funcstate.f->source);
   lexstate.buff = buff;
   lexstate.dyd = dyd;
   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;