Stack indices changed to union's

That will allow to change pointers to offsets while reallocating
the stack.

19 files changed, 384 insertions, 370 deletions

diff --git a/lapi.c b/lapi.c
index 5833c7b0..34e64af1 100644
--- a/lapi.c
+++ b/lapi.c
@@ -60,27 +60,28 @@ const char lua_ident[] =
 static TValue *index2value (lua_State *L, int idx) {
   CallInfo *ci = L->ci;
   if (idx > 0) {
-    StkId o = ci->func + idx;
-    api_check(L, idx <= L->ci->top - (ci->func + 1), "unacceptable index");
-    if (o >= L->top) return &G(L)->nilvalue;
+    StkId o = ci->func.p + idx;
+    api_check(L, idx <= ci->top.p - (ci->func.p + 1), "unacceptable index");
+    if (o >= L->top.p) return &G(L)->nilvalue;
     else return s2v(o);
   }
   else if (!ispseudo(idx)) {  /* negative index */
-    api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
-    return s2v(L->top + idx);
+    api_check(L, idx != 0 && -idx <= L->top.p - (ci->func.p + 1),
+                 "invalid index");
+    return s2v(L->top.p + idx);
   }
   else if (idx == LUA_REGISTRYINDEX)
     return &G(L)->l_registry;
   else {  /* upvalues */
     idx = LUA_REGISTRYINDEX - idx;
     api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large");
-    if (ttisCclosure(s2v(ci->func))) {  /* C closure? */
-      CClosure *func = clCvalue(s2v(ci->func));
+    if (ttisCclosure(s2v(ci->func.p))) {  /* C closure? */
+      CClosure *func = clCvalue(s2v(ci->func.p));
       return (idx <= func->nupvalues) ? &func->upvalue[idx-1]
                                       : &G(L)->nilvalue;
     }
     else {  /* light C function or Lua function (through a hook)?) */
-      api_check(L, ttislcf(s2v(ci->func)), "caller not a C function");
+      api_check(L, ttislcf(s2v(ci->func.p)), "caller not a C function");
       return &G(L)->nilvalue;  /* no upvalues */
     }
   }
@@ -94,14 +95,15 @@ static TValue *index2value (lua_State *L, int idx) {
 l_sinline StkId index2stack (lua_State *L, int idx) {
   CallInfo *ci = L->ci;
   if (idx > 0) {
-    StkId o = ci->func + idx;
-    api_check(L, o < L->top, "invalid index");
+    StkId o = ci->func.p + idx;
+    api_check(L, o < L->top.p, "invalid index");
     return o;
   }
   else {    /* non-positive index */
-    api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
+    api_check(L, idx != 0 && -idx <= L->top.p - (ci->func.p + 1),
+                 "invalid index");
     api_check(L, !ispseudo(idx), "invalid index");
-    return L->top + idx;
+    return L->top.p + idx;
   }
 }
 
@@ -112,12 +114,12 @@ LUA_API int lua_checkstack (lua_State *L, int n) {
   lua_lock(L);
   ci = L->ci;
   api_check(L, n >= 0, "negative 'n'");
-  if (L->stack_last - L->top > n)  /* stack large enough? */
+  if (L->stack_last.p - L->top.p > n)  /* stack large enough? */
     res = 1;  /* yes; check is OK */
   else  /* need to grow stack */
     res = luaD_growstack(L, n, 0);
-  if (res && ci->top < L->top + n)
-    ci->top = L->top + n;  /* adjust frame top */
+  if (res && ci->top.p < L->top.p + n)
+    ci->top.p = L->top.p + n;  /* adjust frame top */
   lua_unlock(L);
   return res;
 }
@@ -129,11 +131,11 @@ LUA_API void lua_xmove (lua_State *from, lua_State *to, int n) {
   lua_lock(to);
   api_checknelems(from, n);
   api_check(from, G(from) == G(to), "moving among independent states");
-  api_check(from, to->ci->top - to->top >= n, "stack overflow");
-  from->top -= n;
+  api_check(from, to->ci->top.p - to->top.p >= n, "stack overflow");
+  from->top.p -= n;
   for (i = 0; i < n; i++) {
-    setobjs2s(to, to->top, from->top + i);
-    to->top++;  /* stack already checked by previous 'api_check' */
+    setobjs2s(to, to->top.p, from->top.p + i);
+    to->top.p++;  /* stack already checked by previous 'api_check' */
   }
   lua_unlock(to);
 }
@@ -167,12 +169,12 @@ LUA_API lua_Number lua_version (lua_State *L) {
 LUA_API int lua_absindex (lua_State *L, int idx) {
   return (idx > 0 || ispseudo(idx))
          ? idx
-         : cast_int(L->top - L->ci->func) + idx;
+         : cast_int(L->top.p - L->ci->func.p) + idx;
 }
 
 
 LUA_API int lua_gettop (lua_State *L) {
-  return cast_int(L->top - (L->ci->func + 1));
+  return cast_int(L->top.p - (L->ci->func.p + 1));
 }
 
 
@@ -182,24 +184,24 @@ LUA_API void lua_settop (lua_State *L, int idx) {
   ptrdiff_t diff;  /* difference for new top */
   lua_lock(L);
   ci = L->ci;
-  func = ci->func;
+  func = ci->func.p;
   if (idx >= 0) {
-    api_check(L, idx <= ci->top - (func + 1), "new top too large");
-    diff = ((func + 1) + idx) - L->top;
+    api_check(L, idx <= ci->top.p - (func + 1), "new top too large");
+    diff = ((func + 1) + idx) - L->top.p;
     for (; diff > 0; diff--)
-      setnilvalue(s2v(L->top++));  /* clear new slots */
+      setnilvalue(s2v(L->top.p++));  /* clear new slots */
   }
   else {
-    api_check(L, -(idx+1) <= (L->top - (func + 1)), "invalid new top");
+    api_check(L, -(idx+1) <= (L->top.p - (func + 1)), "invalid new top");
     diff = idx + 1;  /* will "subtract" index (as it is negative) */
   }
-  api_check(L, L->tbclist < L->top, "previous pop of an unclosed slot");
-  newtop = L->top + diff;
-  if (diff < 0 && L->tbclist >= newtop) {
+  api_check(L, L->tbclist.p < L->top.p, "previous pop of an unclosed slot");
+  newtop = L->top.p + diff;
+  if (diff < 0 && L->tbclist.p >= newtop) {
     lua_assert(hastocloseCfunc(ci->nresults));
     newtop = luaF_close(L, newtop, CLOSEKTOP, 0);
   }
-  L->top = newtop;  /* correct top only after closing any upvalue */
+  L->top.p = newtop;  /* correct top only after closing any upvalue */
   lua_unlock(L);
 }
 
@@ -208,7 +210,7 @@ LUA_API void lua_closeslot (lua_State *L, int idx) {
   StkId level;
   lua_lock(L);
   level = index2stack(L, idx);
-  api_check(L, hastocloseCfunc(L->ci->nresults) && L->tbclist == level,
+  api_check(L, hastocloseCfunc(L->ci->nresults) && L->tbclist.p == level,
      "no variable to close at given level");
   level = luaF_close(L, level, CLOSEKTOP, 0);
   setnilvalue(s2v(level));
@@ -239,7 +241,7 @@ l_sinline void reverse (lua_State *L, StkId from, StkId to) {
 LUA_API void lua_rotate (lua_State *L, int idx, int n) {
   StkId p, t, m;
   lua_lock(L);
-  t = L->top - 1;  /* end of stack segment being rotated */
+  t = L->top.p - 1;  /* end of stack segment being rotated */
   p = index2stack(L, idx);  /* start of segment */
   api_check(L, (n >= 0 ? n : -n) <= (t - p + 1), "invalid 'n'");
   m = (n >= 0 ? t - n : p - n - 1);  /* end of prefix */
@@ -258,7 +260,7 @@ LUA_API void lua_copy (lua_State *L, int fromidx, int toidx) {
   api_check(L, isvalid(L, to), "invalid index");
   setobj(L, to, fr);
   if (isupvalue(toidx))  /* function upvalue? */
-    luaC_barrier(L, clCvalue(s2v(L->ci->func)), fr);
+    luaC_barrier(L, clCvalue(s2v(L->ci->func.p)), fr);
   /* LUA_REGISTRYINDEX does not need gc barrier
      (collector revisits it before finishing collection) */
   lua_unlock(L);
@@ -267,7 +269,7 @@ LUA_API void lua_copy (lua_State *L, int fromidx, int toidx) {
 
 LUA_API void lua_pushvalue (lua_State *L, int idx) {
   lua_lock(L);
-  setobj2s(L, L->top, index2value(L, idx));
+  setobj2s(L, L->top.p, index2value(L, idx));
   api_incr_top(L);
   lua_unlock(L);
 }
@@ -336,12 +338,12 @@ LUA_API void lua_arith (lua_State *L, int op) {
     api_checknelems(L, 2);  /* all other operations expect two operands */
   else {  /* for unary operations, add fake 2nd operand */
     api_checknelems(L, 1);
-    setobjs2s(L, L->top, L->top - 1);
+    setobjs2s(L, L->top.p, L->top.p - 1);
     api_incr_top(L);
   }
   /* first operand at top - 2, second at top - 1; result go to top - 2 */
-  luaO_arith(L, op, s2v(L->top - 2), s2v(L->top - 1), L->top - 2);
-  L->top--;  /* remove second operand */
+  luaO_arith(L, op, s2v(L->top.p - 2), s2v(L->top.p - 1), L->top.p - 2);
+  L->top.p--;  /* remove second operand */
   lua_unlock(L);
 }
 
@@ -367,7 +369,7 @@ LUA_API int lua_compare (lua_State *L, int index1, int index2, int op) {
 
 
 LUA_API size_t lua_stringtonumber (lua_State *L, const char *s) {
-  size_t sz = luaO_str2num(s, s2v(L->top));
+  size_t sz = luaO_str2num(s, s2v(L->top.p));
   if (sz != 0)
     api_incr_top(L);
   return sz;
@@ -494,7 +496,7 @@ LUA_API const void *lua_topointer (lua_State *L, int idx) {
 
 LUA_API void lua_pushnil (lua_State *L) {
   lua_lock(L);
-  setnilvalue(s2v(L->top));
+  setnilvalue(s2v(L->top.p));
   api_incr_top(L);
   lua_unlock(L);
 }
@@ -502,7 +504,7 @@ LUA_API void lua_pushnil (lua_State *L) {
 
 LUA_API void lua_pushnumber (lua_State *L, lua_Number n) {
   lua_lock(L);
-  setfltvalue(s2v(L->top), n);
+  setfltvalue(s2v(L->top.p), n);
   api_incr_top(L);
   lua_unlock(L);
 }
@@ -510,7 +512,7 @@ LUA_API void lua_pushnumber (lua_State *L, lua_Number n) {
 
 LUA_API void lua_pushinteger (lua_State *L, lua_Integer n) {
   lua_lock(L);
-  setivalue(s2v(L->top), n);
+  setivalue(s2v(L->top.p), n);
   api_incr_top(L);
   lua_unlock(L);
 }
@@ -525,7 +527,7 @@ LUA_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) {
   TString *ts;
   lua_lock(L);
   ts = (len == 0) ? luaS_new(L, "") : luaS_newlstr(L, s, len);
-  setsvalue2s(L, L->top, ts);
+  setsvalue2s(L, L->top.p, ts);
   api_incr_top(L);
   luaC_checkGC(L);
   lua_unlock(L);
@@ -536,11 +538,11 @@ LUA_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) {
 LUA_API const char *lua_pushstring (lua_State *L, const char *s) {
   lua_lock(L);
   if (s == NULL)
-    setnilvalue(s2v(L->top));
+    setnilvalue(s2v(L->top.p));
   else {
     TString *ts;
     ts = luaS_new(L, s);
-    setsvalue2s(L, L->top, ts);
+    setsvalue2s(L, L->top.p, ts);
     s = getstr(ts);  /* internal copy's address */
   }
   api_incr_top(L);
@@ -577,7 +579,7 @@ LUA_API const char *lua_pushfstring (lua_State *L, const char *fmt, ...) {
 LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
   lua_lock(L);
   if (n == 0) {
-    setfvalue(s2v(L->top), fn);
+    setfvalue(s2v(L->top.p), fn);
     api_incr_top(L);
   }
   else {
@@ -586,13 +588,13 @@ LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
     api_check(L, n <= MAXUPVAL, "upvalue index too large");
     cl = luaF_newCclosure(L, n);
     cl->f = fn;
-    L->top -= n;
+    L->top.p -= n;
     while (n--) {
-      setobj2n(L, &cl->upvalue[n], s2v(L->top + n));
+      setobj2n(L, &cl->upvalue[n], s2v(L->top.p + n));
       /* does not need barrier because closure is white */
       lua_assert(iswhite(cl));
     }
-    setclCvalue(L, s2v(L->top), cl);
+    setclCvalue(L, s2v(L->top.p), cl);
     api_incr_top(L);
     luaC_checkGC(L);
   }
@@ -603,9 +605,9 @@ LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
 LUA_API void lua_pushboolean (lua_State *L, int b) {
   lua_lock(L);
   if (b)
-    setbtvalue(s2v(L->top));
+    setbtvalue(s2v(L->top.p));
   else
-    setbfvalue(s2v(L->top));
+    setbfvalue(s2v(L->top.p));
   api_incr_top(L);
   lua_unlock(L);
 }
@@ -613,7 +615,7 @@ LUA_API void lua_pushboolean (lua_State *L, int b) {
 
 LUA_API void lua_pushlightuserdata (lua_State *L, void *p) {
   lua_lock(L);
-  setpvalue(s2v(L->top), p);
+  setpvalue(s2v(L->top.p), p);
   api_incr_top(L);
   lua_unlock(L);
 }
@@ -621,7 +623,7 @@ LUA_API void lua_pushlightuserdata (lua_State *L, void *p) {
 
 LUA_API int lua_pushthread (lua_State *L) {
   lua_lock(L);
-  setthvalue(L, s2v(L->top), L);
+  setthvalue(L, s2v(L->top.p), L);
   api_incr_top(L);
   lua_unlock(L);
   return (G(L)->mainthread == L);
@@ -638,16 +640,16 @@ l_sinline int auxgetstr (lua_State *L, const TValue *t, const char *k) {
   const TValue *slot;
   TString *str = luaS_new(L, k);
   if (luaV_fastget(L, t, str, slot, luaH_getstr)) {
-    setobj2s(L, L->top, slot);
+    setobj2s(L, L->top.p, slot);
     api_incr_top(L);
   }
   else {
-    setsvalue2s(L, L->top, str);
+    setsvalue2s(L, L->top.p, str);
     api_incr_top(L);
-    luaV_finishget(L, t, s2v(L->top - 1), L->top - 1, slot);
+    luaV_finishget(L, t, s2v(L->top.p - 1), L->top.p - 1, slot);
   }
   lua_unlock(L);
-  return ttype(s2v(L->top - 1));
+  return ttype(s2v(L->top.p - 1));
 }
 
 
@@ -674,13 +676,13 @@ LUA_API int lua_gettable (lua_State *L, int idx) {
   TValue *t;
   lua_lock(L);
   t = index2value(L, idx);
-  if (luaV_fastget(L, t, s2v(L->top - 1), slot, luaH_get)) {
-    setobj2s(L, L->top - 1, slot);
+  if (luaV_fastget(L, t, s2v(L->top.p - 1), slot, luaH_get)) {
+    setobj2s(L, L->top.p - 1, slot);
   }
   else
-    luaV_finishget(L, t, s2v(L->top - 1), L->top - 1, slot);
+    luaV_finishget(L, t, s2v(L->top.p - 1), L->top.p - 1, slot);
   lua_unlock(L);
-  return ttype(s2v(L->top - 1));
+  return ttype(s2v(L->top.p - 1));
 }
 
 
@@ -696,27 +698,27 @@ LUA_API int lua_geti (lua_State *L, int idx, lua_Integer n) {
   lua_lock(L);
   t = index2value(L, idx);
   if (luaV_fastgeti(L, t, n, slot)) {
-    setobj2s(L, L->top, slot);
+    setobj2s(L, L->top.p, slot);
   }
   else {
     TValue aux;
     setivalue(&aux, n);
-    luaV_finishget(L, t, &aux, L->top, slot);
+    luaV_finishget(L, t, &aux, L->top.p, slot);
   }
   api_incr_top(L);
   lua_unlock(L);
-  return ttype(s2v(L->top - 1));
+  return ttype(s2v(L->top.p - 1));
 }
 
 
 l_sinline int finishrawget (lua_State *L, const TValue *val) {
   if (isempty(val))  /* avoid copying empty items to the stack */
-    setnilvalue(s2v(L->top));
+    setnilvalue(s2v(L->top.p));
   else
-    setobj2s(L, L->top, val);
+    setobj2s(L, L->top.p, val);
   api_incr_top(L);
   lua_unlock(L);
-  return ttype(s2v(L->top - 1));
+  return ttype(s2v(L->top.p - 1));
 }
 
 
@@ -733,8 +735,8 @@ LUA_API int lua_rawget (lua_State *L, int idx) {
   lua_lock(L);
   api_checknelems(L, 1);
   t = gettable(L, idx);
-  val = luaH_get(t, s2v(L->top - 1));
-  L->top--;  /* remove key */
+  val = luaH_get(t, s2v(L->top.p - 1));
+  L->top.p--;  /* remove key */
   return finishrawget(L, val);
 }
 
@@ -761,7 +763,7 @@ LUA_API void lua_createtable (lua_State *L, int narray, int nrec) {
   Table *t;
   lua_lock(L);
   t = luaH_new(L);
-  sethvalue2s(L, L->top, t);
+  sethvalue2s(L, L->top.p, t);
   api_incr_top(L);
   if (narray > 0 || nrec > 0)
     luaH_resize(L, t, narray, nrec);
@@ -788,7 +790,7 @@ LUA_API int lua_getmetatable (lua_State *L, int objindex) {
       break;
   }
   if (mt != NULL) {
-    sethvalue2s(L, L->top, mt);
+    sethvalue2s(L, L->top.p, mt);
     api_incr_top(L);
     res = 1;
   }
@@ -804,12 +806,12 @@ LUA_API int lua_getiuservalue (lua_State *L, int idx, int n) {
   o = index2value(L, idx);
   api_check(L, ttisfulluserdata(o), "full userdata expected");
   if (n <= 0 || n > uvalue(o)->nuvalue) {
-    setnilvalue(s2v(L->top));
+    setnilvalue(s2v(L->top.p));
     t = LUA_TNONE;
   }
   else {
-    setobj2s(L, L->top, &uvalue(o)->uv[n - 1].uv);
-    t = ttype(s2v(L->top));
+    setobj2s(L, L->top.p, &uvalue(o)->uv[n - 1].uv);
+    t = ttype(s2v(L->top.p));
   }
   api_incr_top(L);
   lua_unlock(L);
@@ -829,14 +831,14 @@ static void auxsetstr (lua_State *L, const TValue *t, const char *k) {
   TString *str = luaS_new(L, k);
   api_checknelems(L, 1);
   if (luaV_fastget(L, t, str, slot, luaH_getstr)) {
-    luaV_finishfastset(L, t, slot, s2v(L->top - 1));
-    L->top--;  /* pop value */
+    luaV_finishfastset(L, t, slot, s2v(L->top.p - 1));
+    L->top.p--;  /* pop value */
   }
   else {
-    setsvalue2s(L, L->top, str);  /* push 'str' (to make it a TValue) */
+    setsvalue2s(L, L->top.p, str);  /* push 'str' (to make it a TValue) */
     api_incr_top(L);
-    luaV_finishset(L, t, s2v(L->top - 1), s2v(L->top - 2), slot);
-    L->top -= 2;  /* pop value and key */
+    luaV_finishset(L, t, s2v(L->top.p - 1), s2v(L->top.p - 2), slot);
+    L->top.p -= 2;  /* pop value and key */
   }
   lua_unlock(L);  /* lock done by caller */
 }
@@ -856,12 +858,12 @@ LUA_API void lua_settable (lua_State *L, int idx) {
   lua_lock(L);
   api_checknelems(L, 2);
   t = index2value(L, idx);
-  if (luaV_fastget(L, t, s2v(L->top - 2), slot, luaH_get)) {
-    luaV_finishfastset(L, t, slot, s2v(L->top - 1));
+  if (luaV_fastget(L, t, s2v(L->top.p - 2), slot, luaH_get)) {
+    luaV_finishfastset(L, t, slot, s2v(L->top.p - 1));
   }
   else
-    luaV_finishset(L, t, s2v(L->top - 2), s2v(L->top - 1), slot);
-  L->top -= 2;  /* pop index and value */
+    luaV_finishset(L, t, s2v(L->top.p - 2), s2v(L->top.p - 1), slot);
+  L->top.p -= 2;  /* pop index and value */
   lua_unlock(L);
 }
 
@@ -879,14 +881,14 @@ LUA_API void lua_seti (lua_State *L, int idx, lua_Integer n) {
   api_checknelems(L, 1);
   t = index2value(L, idx);
   if (luaV_fastgeti(L, t, n, slot)) {
-    luaV_finishfastset(L, t, slot, s2v(L->top - 1));
+    luaV_finishfastset(L, t, slot, s2v(L->top.p - 1));
   }
   else {
     TValue aux;
     setivalue(&aux, n);
-    luaV_finishset(L, t, &aux, s2v(L->top - 1), slot);
+    luaV_finishset(L, t, &aux, s2v(L->top.p - 1), slot);
   }
-  L->top--;  /* pop value */
+  L->top.p--;  /* pop value */
   lua_unlock(L);
 }
 
@@ -896,16 +898,16 @@ static void aux_rawset (lua_State *L, int idx, TValue *key, int n) {
   lua_lock(L);
   api_checknelems(L, n);
   t = gettable(L, idx);
-  luaH_set(L, t, key, s2v(L->top - 1));
+  luaH_set(L, t, key, s2v(L->top.p - 1));
   invalidateTMcache(t);
-  luaC_barrierback(L, obj2gco(t), s2v(L->top - 1));
-  L->top -= n;
+  luaC_barrierback(L, obj2gco(t), s2v(L->top.p - 1));
+  L->top.p -= n;
   lua_unlock(L);
 }
 
 
 LUA_API void lua_rawset (lua_State *L, int idx) {
-  aux_rawset(L, idx, s2v(L->top - 2), 2);
+  aux_rawset(L, idx, s2v(L->top.p - 2), 2);
 }
 
 
@@ -921,9 +923,9 @@ LUA_API void lua_rawseti (lua_State *L, int idx, lua_Integer n) {
   lua_lock(L);
   api_checknelems(L, 1);
   t = gettable(L, idx);
-  luaH_setint(L, t, n, s2v(L->top - 1));
-  luaC_barrierback(L, obj2gco(t), s2v(L->top - 1));
-  L->top--;
+  luaH_setint(L, t, n, s2v(L->top.p - 1));
+  luaC_barrierback(L, obj2gco(t), s2v(L->top.p - 1));
+  L->top.p--;
   lua_unlock(L);
 }
 
@@ -934,11 +936,11 @@ LUA_API int lua_setmetatable (lua_State *L, int objindex) {
   lua_lock(L);
   api_checknelems(L, 1);
   obj = index2value(L, objindex);
-  if (ttisnil(s2v(L->top - 1)))
+  if (ttisnil(s2v(L->top.p - 1)))
     mt = NULL;
   else {
-    api_check(L, ttistable(s2v(L->top - 1)), "table expected");
-    mt = hvalue(s2v(L->top - 1));
+    api_check(L, ttistable(s2v(L->top.p - 1)), "table expected");
+    mt = hvalue(s2v(L->top.p - 1));
   }
   switch (ttype(obj)) {
     case LUA_TTABLE: {
@@ -962,7 +964,7 @@ LUA_API int lua_setmetatable (lua_State *L, int objindex) {
       break;
     }
   }
-  L->top--;
+  L->top.p--;
   lua_unlock(L);
   return 1;
 }
@@ -978,11 +980,11 @@ LUA_API int lua_setiuservalue (lua_State *L, int idx, int n) {
   if (!(cast_uint(n) - 1u < cast_uint(uvalue(o)->nuvalue)))
     res = 0;  /* 'n' not in [1, uvalue(o)->nuvalue] */
   else {
-    setobj(L, &uvalue(o)->uv[n - 1].uv, s2v(L->top - 1));
-    luaC_barrierback(L, gcvalue(o), s2v(L->top - 1));
+    setobj(L, &uvalue(o)->uv[n - 1].uv, s2v(L->top.p - 1));
+    luaC_barrierback(L, gcvalue(o), s2v(L->top.p - 1));
     res = 1;
   }
-  L->top--;
+  L->top.p--;
   lua_unlock(L);
   return res;
 }
@@ -994,7 +996,8 @@ LUA_API int lua_setiuservalue (lua_State *L, int idx, int n) {
 
 
 #define checkresults(L,na,nr) \
-     api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)), \
+     api_check(L, (nr) == LUA_MULTRET \
+               || (L->ci->top.p - L->top.p >= (nr) - (na)), \
 	"results from function overflow current stack size")
 
 
@@ -1007,7 +1010,7 @@ LUA_API void lua_callk (lua_State *L, int nargs, int nresults,
   api_checknelems(L, nargs+1);
   api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
   checkresults(L, nargs, nresults);
-  func = L->top - (nargs+1);
+  func = L->top.p - (nargs+1);
   if (k != NULL && yieldable(L)) {  /* need to prepare continuation? */
     L->ci->u.c.k = k;  /* save continuation */
     L->ci->u.c.ctx = ctx;  /* save context */
@@ -1055,7 +1058,7 @@ LUA_API int lua_pcallk (lua_State *L, int nargs, int nresults, int errfunc,
     api_check(L, ttisfunction(s2v(o)), "error handler must be a function");
     func = savestack(L, o);
   }
-  c.func = L->top - (nargs+1);  /* function to be called */
+  c.func = L->top.p - (nargs+1);  /* function to be called */
   if (k == NULL || !yieldable(L)) {  /* no continuation or no yieldable? */
     c.nresults = nresults;  /* do a 'conventional' protected call */
     status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func);
@@ -1090,12 +1093,12 @@ LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data,
   luaZ_init(L, &z, reader, data);
   status = luaD_protectedparser(L, &z, chunkname, mode);
   if (status == LUA_OK) {  /* no errors? */
-    LClosure *f = clLvalue(s2v(L->top - 1));  /* get newly created function */
+    LClosure *f = clLvalue(s2v(L->top.p - 1));  /* get new function */
     if (f->nupvalues >= 1) {  /* does it have an upvalue? */
       /* get global table from registry */
       const TValue *gt = getGtable(L);
       /* set global table as 1st upvalue of 'f' (may be LUA_ENV) */
-      setobj(L, f->upvals[0]->v, gt);
+      setobj(L, f->upvals[0]->v.p, gt);
       luaC_barrier(L, f->upvals[0], gt);
     }
   }
@@ -1109,7 +1112,7 @@ LUA_API int lua_dump (lua_State *L, lua_Writer writer, void *data, int strip) {
   TValue *o;
   lua_lock(L);
   api_checknelems(L, 1);
-  o = s2v(L->top - 1);
+  o = s2v(L->top.p - 1);
   if (isLfunction(o))
     status = luaU_dump(L, getproto(o), writer, data, strip);
   else
@@ -1235,7 +1238,7 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
 LUA_API int lua_error (lua_State *L) {
   TValue *errobj;
   lua_lock(L);
-  errobj = s2v(L->top - 1);
+  errobj = s2v(L->top.p - 1);
   api_checknelems(L, 1);
   /* error object is the memory error message? */
   if (ttisshrstring(errobj) && eqshrstr(tsvalue(errobj), G(L)->memerrmsg))
@@ -1253,12 +1256,12 @@ LUA_API int lua_next (lua_State *L, int idx) {
   lua_lock(L);
   api_checknelems(L, 1);
   t = gettable(L, idx);
-  more = luaH_next(L, t, L->top - 1);
+  more = luaH_next(L, t, L->top.p - 1);
   if (more) {
     api_incr_top(L);
   }
   else  /* no more elements */
-    L->top -= 1;  /* remove key */
+    L->top.p -= 1;  /* remove key */
   lua_unlock(L);
   return more;
 }
@@ -1270,7 +1273,7 @@ LUA_API void lua_toclose (lua_State *L, int idx) {
   lua_lock(L);
   o = index2stack(L, idx);
   nresults = L->ci->nresults;
-  api_check(L, L->tbclist < o, "given index below or equal a marked one");
+  api_check(L, L->tbclist.p < o, "given index below or equal a marked one");
   luaF_newtbcupval(L, o);  /* create new to-be-closed upvalue */
   if (!hastocloseCfunc(nresults))  /* function not marked yet? */
     L->ci->nresults = codeNresults(nresults);  /* mark it */
@@ -1285,7 +1288,7 @@ LUA_API void lua_concat (lua_State *L, int n) {
   if (n > 0)
     luaV_concat(L, n);
   else {  /* nothing to concatenate */
-    setsvalue2s(L, L->top, luaS_newlstr(L, "", 0));  /* push empty string */
+    setsvalue2s(L, L->top.p, luaS_newlstr(L, "", 0));  /* push empty string */
     api_incr_top(L);
   }
   luaC_checkGC(L);
@@ -1297,7 +1300,7 @@ LUA_API void lua_len (lua_State *L, int idx) {
   TValue *t;
   lua_lock(L);
   t = index2value(L, idx);
-  luaV_objlen(L, L->top, t);
+  luaV_objlen(L, L->top.p, t);
   api_incr_top(L);
   lua_unlock(L);
 }
@@ -1342,7 +1345,7 @@ LUA_API void *lua_newuserdatauv (lua_State *L, size_t size, int nuvalue) {
   lua_lock(L);
   api_check(L, 0 <= nuvalue && nuvalue < USHRT_MAX, "invalid value");
   u = luaS_newudata(L, size, nuvalue);
-  setuvalue(L, s2v(L->top), u);
+  setuvalue(L, s2v(L->top.p), u);
   api_incr_top(L);
   luaC_checkGC(L);
   lua_unlock(L);
@@ -1368,7 +1371,7 @@ static const char *aux_upvalue (TValue *fi, int n, TValue **val,
       Proto *p = f->p;
       if (!(cast_uint(n) - 1u  < cast_uint(p->sizeupvalues)))
         return NULL;  /* 'n' not in [1, p->sizeupvalues] */
-      *val = f->upvals[n-1]->v;
+      *val = f->upvals[n-1]->v.p;
       if (owner) *owner = obj2gco(f->upvals[n - 1]);
       name = p->upvalues[n-1].name;
       return (name == NULL) ? "(no name)" : getstr(name);
@@ -1384,7 +1387,7 @@ LUA_API const char *lua_getupvalue (lua_State *L, int funcindex, int n) {
   lua_lock(L);
   name = aux_upvalue(index2value(L, funcindex), n, &val, NULL);
   if (name) {
-    setobj2s(L, L->top, val);
+    setobj2s(L, L->top.p, val);
     api_incr_top(L);
   }
   lua_unlock(L);
@@ -1402,8 +1405,8 @@ LUA_API const char *lua_setupvalue (lua_State *L, int funcindex, int n) {
   api_checknelems(L, 1);
   name = aux_upvalue(fi, n, &val, &owner);
   if (name) {
-    L->top--;
-    setobj(L, val, s2v(L->top));
+    L->top.p--;
+    setobj(L, val, s2v(L->top.p));
     luaC_barrier(L, owner, val);
   }
   lua_unlock(L);
diff --git a/lapi.h b/lapi.h
index 9e99cc44..a742427c 100644
--- a/lapi.h
+++ b/lapi.h
@@ -12,23 +12,26 @@
 #include "lstate.h"
 
 
-/* Increments 'L->top', checking for stack overflows */
-#define api_incr_top(L)   {L->top++; api_check(L, L->top <= L->ci->top, \
-				"stack overflow");}
+/* Increments 'L->top.p', checking for stack overflows */
+#define api_incr_top(L)	{L->top.p++; \
+			 api_check(L, L->top.p <= L->ci->top.p, \
+					"stack overflow");}
 
 
 /*
 ** If a call returns too many multiple returns, the callee may not have
 ** stack space to accommodate all results. In this case, this macro
-** increases its stack space ('L->ci->top').
+** increases its stack space ('L->ci->top.p').
 */
 #define adjustresults(L,nres) \
-    { if ((nres) <= LUA_MULTRET && L->ci->top < L->top) L->ci->top = L->top; }
+    { if ((nres) <= LUA_MULTRET && L->ci->top.p < L->top.p) \
+	L->ci->top.p = L->top.p; }
 
 
 /* Ensure the stack has at least 'n' elements */
-#define api_checknelems(L,n)	api_check(L, (n) < (L->top - L->ci->func), \
-				  "not enough elements in the stack")
+#define api_checknelems(L,n) \
+	api_check(L, (n) < (L->top.p - L->ci->func.p), \
+			  "not enough elements in the stack")
 
 
 /*
diff --git a/ldebug.c b/ldebug.c
index fa15eaf6..3fae5cf2 100644
--- a/ldebug.c
+++ b/ldebug.c
@@ -182,10 +182,10 @@ static const char *upvalname (const Proto *p, int uv) {
 
 
 static const char *findvararg (CallInfo *ci, int n, StkId *pos) {
-  if (clLvalue(s2v(ci->func))->p->is_vararg) {
+  if (clLvalue(s2v(ci->func.p))->p->is_vararg) {
     int nextra = ci->u.l.nextraargs;
     if (n >= -nextra) {  /* 'n' is negative */
-      *pos = ci->func - nextra - (n + 1);
+      *pos = ci->func.p - nextra - (n + 1);
       return "(vararg)";  /* generic name for any vararg */
     }
   }
@@ -194,7 +194,7 @@ static const char *findvararg (CallInfo *ci, int n, StkId *pos) {
 
 
 const char *luaG_findlocal (lua_State *L, CallInfo *ci, int n, StkId *pos) {
-  StkId base = ci->func + 1;
+  StkId base = ci->func.p + 1;
   const char *name = NULL;
   if (isLua(ci)) {
     if (n < 0)  /* access to vararg values? */
@@ -203,7 +203,7 @@ const char *luaG_findlocal (lua_State *L, CallInfo *ci, int n, StkId *pos) {
       name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));
   }
   if (name == NULL) {  /* no 'standard' name? */
-    StkId limit = (ci == L->ci) ? L->top : ci->next->func;
+    StkId limit = (ci == L->ci) ? L->top.p : ci->next->func.p;
     if (limit - base >= n && n > 0) {  /* is 'n' inside 'ci' stack? */
       /* generic name for any valid slot */
       name = isLua(ci) ? "(temporary)" : "(C temporary)";
@@ -221,16 +221,16 @@ LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
   const char *name;
   lua_lock(L);
   if (ar == NULL) {  /* information about non-active function? */
-    if (!isLfunction(s2v(L->top - 1)))  /* not a Lua function? */
+    if (!isLfunction(s2v(L->top.p - 1)))  /* not a Lua function? */
       name = NULL;
     else  /* consider live variables at function start (parameters) */
-      name = luaF_getlocalname(clLvalue(s2v(L->top - 1))->p, n, 0);
+      name = luaF_getlocalname(clLvalue(s2v(L->top.p - 1))->p, n, 0);
   }
   else {  /* active function; get information through 'ar' */
     StkId pos = NULL;  /* to avoid warnings */
     name = luaG_findlocal(L, ar->i_ci, n, &pos);
     if (name) {
-      setobjs2s(L, L->top, pos);
+      setobjs2s(L, L->top.p, pos);
       api_incr_top(L);
     }
   }
@@ -245,8 +245,8 @@ LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
   lua_lock(L);
   name = luaG_findlocal(L, ar->i_ci, n, &pos);
   if (name) {
-    setobjs2s(L, pos, L->top - 1);
-    L->top--;  /* pop value */
+    setobjs2s(L, pos, L->top.p - 1);
+    L->top.p--;  /* pop value */
   }
   lua_unlock(L);
   return name;
@@ -289,7 +289,7 @@ static int nextline (const Proto *p, int currentline, int pc) {
 
 static void collectvalidlines (lua_State *L, Closure *f) {
   if (noLuaClosure(f)) {
-    setnilvalue(s2v(L->top));
+    setnilvalue(s2v(L->top.p));
     api_incr_top(L);
   }
   else {
@@ -298,7 +298,7 @@ static void collectvalidlines (lua_State *L, Closure *f) {
     const Proto *p = f->l.p;
     int currentline = p->linedefined;
     Table *t = luaH_new(L);  /* new table to store active lines */
-    sethvalue2s(L, L->top, t);  /* push it on stack */
+    sethvalue2s(L, L->top.p, t);  /* push it on stack */
     api_incr_top(L);
     setbtvalue(&v);  /* boolean 'true' to be the value of all indices */
     if (!p->is_vararg)  /* regular function? */
@@ -388,20 +388,20 @@ LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
   lua_lock(L);
   if (*what == '>') {
     ci = NULL;
-    func = s2v(L->top - 1);
+    func = s2v(L->top.p - 1);
     api_check(L, ttisfunction(func), "function expected");
     what++;  /* skip the '>' */
-    L->top--;  /* pop function */
+    L->top.p--;  /* pop function */
   }
   else {
     ci = ar->i_ci;
-    func = s2v(ci->func);
+    func = s2v(ci->func.p);
     lua_assert(ttisfunction(func));
   }
   cl = ttisclosure(func) ? clvalue(func) : NULL;
   status = auxgetinfo(L, what, ar, cl, ci);
   if (strchr(what, 'f')) {
-    setobj2s(L, L->top, func);
+    setobj2s(L, L->top.p, func);
     api_incr_top(L);
   }
   if (strchr(what, 'L'))
@@ -663,7 +663,7 @@ static const char *funcnamefromcall (lua_State *L, CallInfo *ci,
 */
 static int isinstack (CallInfo *ci, const TValue *o) {
   StkId pos;
-  for (pos = ci->func + 1; pos < ci->top; pos++) {
+  for (pos = ci->func.p + 1; pos < ci->top.p; pos++) {
     if (o == s2v(pos))
       return 1;
   }
@@ -681,7 +681,7 @@ static const char *getupvalname (CallInfo *ci, const TValue *o,
   LClosure *c = ci_func(ci);
   int i;
   for (i = 0; i < c->nupvalues; i++) {
-    if (c->upvals[i]->v == o) {
+    if (c->upvals[i]->v.p == o) {
       *name = upvalname(c->p, i);
       return "upvalue";
     }
@@ -710,7 +710,7 @@ static const char *varinfo (lua_State *L, const TValue *o) {
     kind = getupvalname(ci, o, &name);  /* check whether 'o' is an upvalue */
     if (!kind && isinstack(ci, o))  /* no? try a register */
       kind = getobjname(ci_func(ci)->p, currentpc(ci),
-                        cast_int(cast(StkId, o) - (ci->func + 1)), &name);
+                        cast_int(cast(StkId, o) - (ci->func.p + 1)), &name);
   }
   return formatvarinfo(L, kind, name);
 }
@@ -807,10 +807,10 @@ l_noret luaG_errormsg (lua_State *L) {
   if (L->errfunc != 0) {  /* is there an error handling function? */
     StkId errfunc = restorestack(L, L->errfunc);
     lua_assert(ttisfunction(s2v(errfunc)));
-    setobjs2s(L, L->top, L->top - 1);  /* move argument */
-    setobjs2s(L, L->top - 1, errfunc);  /* push function */
-    L->top++;  /* assume EXTRA_STACK */
-    luaD_callnoyield(L, L->top - 2, 1);  /* call it */
+    setobjs2s(L, L->top.p, L->top.p - 1);  /* move argument */
+    setobjs2s(L, L->top.p - 1, errfunc);  /* push function */
+    L->top.p++;  /* assume EXTRA_STACK */
+    luaD_callnoyield(L, L->top.p - 2, 1);  /* call it */
   }
   luaD_throw(L, LUA_ERRRUN);
 }
@@ -826,8 +826,8 @@ l_noret luaG_runerror (lua_State *L, const char *fmt, ...) {
   va_end(argp);
   if (isLua(ci)) {  /* if Lua function, add source:line information */
     luaG_addinfo(L, msg, ci_func(ci)->p->source, getcurrentline(ci));
-    setobjs2s(L, L->top - 2, L->top - 1);  /* remove 'msg' from the stack */
-    L->top--;
+    setobjs2s(L, L->top.p - 2, L->top.p - 1);  /* remove 'msg' */
+    L->top.p--;
   }
   luaG_errormsg(L);
 }
@@ -872,7 +872,7 @@ static int changedline (const Proto *p, int oldpc, int newpc) {
 ** invalid; if so, use zero as a valid value. (A wrong but valid 'oldpc'
 ** at most causes an extra call to a line hook.)
 ** This function is not "Protected" when called, so it should correct
-** 'L->top' before calling anything that can run the GC.
+** 'L->top.p' before calling anything that can run the GC.
 */
 int luaG_traceexec (lua_State *L, const Instruction *pc) {
   CallInfo *ci = L->ci;
@@ -895,7 +895,7 @@ int luaG_traceexec (lua_State *L, const Instruction *pc) {
     return 1;  /* do not call hook again (VM yielded, so it did not move) */
   }
   if (!isIT(*(ci->u.l.savedpc - 1)))  /* top not being used? */
-    L->top = ci->top;  /* correct top */
+    L->top.p = ci->top.p;  /* correct top */
   if (counthook)
     luaD_hook(L, LUA_HOOKCOUNT, -1, 0, 0);  /* call count hook */
   if (mask & LUA_MASKLINE) {
diff --git a/ldebug.h b/ldebug.h
index 974960e9..2c3074c6 100644
--- a/ldebug.h
+++ b/ldebug.h
@@ -15,7 +15,7 @@
 
 
 /* Active Lua function (given call info) */
-#define ci_func(ci)		(clLvalue(s2v((ci)->func)))
+#define ci_func(ci)		(clLvalue(s2v((ci)->func.p)))
 
 
 #define resethookcount(L)	(L->hookcount = L->basehookcount)
diff --git a/ldo.c b/ldo.c
index 419b3db9..d45c74da 100644
--- a/ldo.c
+++ b/ldo.c
@@ -104,11 +104,11 @@ void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {
     }
     default: {
       lua_assert(errorstatus(errcode));  /* real error */
-      setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
+      setobjs2s(L, oldtop, L->top.p - 1);  /* error message on current top */
       break;
     }
   }
-  L->top = oldtop + 1;
+  L->top.p = oldtop + 1;
 }
 
 
@@ -121,7 +121,7 @@ l_noret luaD_throw (lua_State *L, int errcode) {
     global_State *g = G(L);
     errcode = luaE_resetthread(L, errcode);  /* close all upvalues */
     if (g->mainthread->errorJmp) {  /* main thread has a handler? */
-      setobjs2s(L, g->mainthread->top++, L->top - 1);  /* copy error obj. */
+      setobjs2s(L, g->mainthread->top.p++, L->top.p - 1);  /* copy error obj. */
       luaD_throw(g->mainthread, errcode);  /* re-throw in main thread */
     }
     else {  /* no handler at all; abort */
@@ -160,13 +160,13 @@ int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
 static void correctstack (lua_State *L, StkId oldstack, StkId newstack) {
   CallInfo *ci;
   UpVal *up;
-  L->top = (L->top - oldstack) + newstack;
-  L->tbclist = (L->tbclist - oldstack) + newstack;
+  L->top.p = (L->top.p - oldstack) + newstack;
+  L->tbclist.p = (L->tbclist.p - oldstack) + newstack;
   for (up = L->openupval; up != NULL; up = up->u.open.next)
-    up->v = s2v((uplevel(up) - oldstack) + newstack);
+    up->v.p = s2v((uplevel(up) - oldstack) + newstack);
   for (ci = L->ci; ci != NULL; ci = ci->previous) {
-    ci->top = (ci->top - oldstack) + newstack;
-    ci->func = (ci->func - oldstack) + newstack;
+    ci->top.p = (ci->top.p - oldstack) + newstack;
+    ci->func.p = (ci->func.p - oldstack) + newstack;
     if (isLua(ci))
       ci->u.l.trap = 1;  /* signal to update 'trap' in 'luaV_execute' */
   }
@@ -176,7 +176,6 @@ static void correctstack (lua_State *L, StkId oldstack, StkId newstack) {
 /* some space for error handling */
 #define ERRORSTACKSIZE	(LUAI_MAXSTACK + 200)
 
-
 /*
 ** Reallocate the stack to a new size, correcting all pointers into
 ** it. (There are pointers to a stack from its upvalues, from its list
@@ -201,13 +200,13 @@ int luaD_reallocstack (lua_State *L, int newsize, int raiseerror) {
   }
   /* number of elements to be copied to the new stack */
   i = ((oldsize <= newsize) ? oldsize : newsize) + EXTRA_STACK;
-  memcpy(newstack, L->stack, i * sizeof(StackValue));
+  memcpy(newstack, L->stack.p, i * sizeof(StackValue));
   for (; i < newsize + EXTRA_STACK; i++)
     setnilvalue(s2v(newstack + i)); /* erase new segment */
-  correctstack(L, L->stack, newstack);
-  luaM_freearray(L, L->stack, oldsize + EXTRA_STACK);
-  L->stack = newstack;
-  L->stack_last = L->stack + newsize;
+  correctstack(L, L->stack.p, newstack);
+  luaM_freearray(L, L->stack.p, oldsize + EXTRA_STACK);
+  L->stack.p = newstack;
+  L->stack_last.p = L->stack.p + newsize;
   return 1;
 }
 
@@ -229,7 +228,7 @@ int luaD_growstack (lua_State *L, int n, int raiseerror) {
   }
   else if (n < LUAI_MAXSTACK) {  /* avoids arithmetic overflows */
     int newsize = 2 * size;  /* tentative new size */
-    int needed = cast_int(L->top - L->stack) + n;
+    int needed = cast_int(L->top.p - L->stack.p) + n;
     if (newsize > LUAI_MAXSTACK)  /* cannot cross the limit */
       newsize = LUAI_MAXSTACK;
     if (newsize < needed)  /* but must respect what was asked for */
@@ -253,12 +252,12 @@ int luaD_growstack (lua_State *L, int n, int raiseerror) {
 static int stackinuse (lua_State *L) {
   CallInfo *ci;
   int res;
-  StkId lim = L->top;
+  StkId lim = L->top.p;
   for (ci = L->ci; ci != NULL; ci = ci->previous) {
-    if (lim < ci->top) lim = ci->top;
+    if (lim < ci->top.p) lim = ci->top.p;
   }
-  lua_assert(lim <= L->stack_last + EXTRA_STACK);
-  res = cast_int(lim - L->stack) + 1;  /* part of stack in use */
+  lua_assert(lim <= L->stack_last.p + EXTRA_STACK);
+  res = cast_int(lim - L->stack.p) + 1;  /* part of stack in use */
   if (res < LUA_MINSTACK)
     res = LUA_MINSTACK;  /* ensure a minimum size */
   return res;
@@ -295,7 +294,7 @@ void luaD_shrinkstack (lua_State *L) {
 
 void luaD_inctop (lua_State *L) {
   luaD_checkstack(L, 1);
-  L->top++;
+  L->top.p++;
 }
 
 /* }================================================================== */
@@ -312,8 +311,8 @@ void luaD_hook (lua_State *L, int event, int line,
   if (hook && L->allowhook) {  /* make sure there is a hook */
     int mask = CIST_HOOKED;
     CallInfo *ci = L->ci;
-    ptrdiff_t top = savestack(L, L->top);  /* preserve original 'top' */
-    ptrdiff_t ci_top = savestack(L, ci->top);  /* idem for 'ci->top' */
+    ptrdiff_t top = savestack(L, L->top.p);  /* preserve original 'top' */
+    ptrdiff_t ci_top = savestack(L, ci->top.p);  /* idem for 'ci->top' */
     lua_Debug ar;
     ar.event = event;
     ar.currentline = line;
@@ -323,11 +322,11 @@ void luaD_hook (lua_State *L, int event, int line,
       ci->u2.transferinfo.ftransfer = ftransfer;
       ci->u2.transferinfo.ntransfer = ntransfer;
     }
-    if (isLua(ci) && L->top < ci->top)
-      L->top = ci->top;  /* protect entire activation register */
+    if (isLua(ci) && L->top.p < ci->top.p)
+      L->top.p = ci->top.p;  /* protect entire activation register */
     luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
-    if (ci->top < L->top + LUA_MINSTACK)
-      ci->top = L->top + LUA_MINSTACK;
+    if (ci->top.p < L->top.p + LUA_MINSTACK)
+      ci->top.p = L->top.p + LUA_MINSTACK;
     L->allowhook = 0;  /* cannot call hooks inside a hook */
     ci->callstatus |= mask;
     lua_unlock(L);
@@ -335,8 +334,8 @@ void luaD_hook (lua_State *L, int event, int line,
     lua_lock(L);
     lua_assert(!L->allowhook);
     L->allowhook = 1;
-    ci->top = restorestack(L, ci_top);
-    L->top = restorestack(L, top);
+    ci->top.p = restorestack(L, ci_top);
+    L->top.p = restorestack(L, top);
     ci->callstatus &= ~mask;
   }
 }
@@ -367,7 +366,7 @@ void luaD_hookcall (lua_State *L, CallInfo *ci) {
 */
 static void rethook (lua_State *L, CallInfo *ci, int nres) {
   if (L->hookmask & LUA_MASKRET) {  /* is return hook on? */
-    StkId firstres = L->top - nres;  /* index of first result */
+    StkId firstres = L->top.p - nres;  /* index of first result */
     int delta = 0;  /* correction for vararg functions */
     int ftransfer;
     if (isLua(ci)) {
@@ -375,10 +374,10 @@ static void rethook (lua_State *L, CallInfo *ci, int nres) {
       if (p->is_vararg)
         delta = ci->u.l.nextraargs + p->numparams + 1;
     }
-    ci->func += delta;  /* if vararg, back to virtual 'func' */
-    ftransfer = cast(unsigned short, firstres - ci->func);
+    ci->func.p += delta;  /* if vararg, back to virtual 'func' */
+    ftransfer = cast(unsigned short, firstres - ci->func.p);
     luaD_hook(L, LUA_HOOKRET, -1, ftransfer, nres);  /* call it */
-    ci->func -= delta;
+    ci->func.p -= delta;
   }
   if (isLua(ci = ci->previous))
     L->oldpc = pcRel(ci->u.l.savedpc, ci_func(ci)->p);  /* set 'oldpc' */
@@ -397,9 +396,9 @@ StkId luaD_tryfuncTM (lua_State *L, StkId func) {
   tm = luaT_gettmbyobj(L, s2v(func), TM_CALL);  /* (after previous GC) */
   if (l_unlikely(ttisnil(tm)))
     luaG_callerror(L, s2v(func));  /* nothing to call */
-  for (p = L->top; p > func; p--)  /* open space for metamethod */
+  for (p = L->top.p; p > func; p--)  /* open space for metamethod */
     setobjs2s(L, p, p-1);
-  L->top++;  /* stack space pre-allocated by the caller */
+  L->top.p++;  /* stack space pre-allocated by the caller */
   setobj2s(L, func, tm);  /* metamethod is the new function to be called */
   return func;
 }
@@ -416,14 +415,14 @@ l_sinline void moveresults (lua_State *L, StkId res, int nres, int wanted) {
   int i;
   switch (wanted) {  /* handle typical cases separately */
     case 0:  /* no values needed */
-      L->top = res;
+      L->top.p = res;
       return;
     case 1:  /* one value needed */
       if (nres == 0)   /* no results? */
         setnilvalue(s2v(res));  /* adjust with nil */
       else  /* at least one result */
-        setobjs2s(L, res, L->top - nres);  /* move it to proper place */
-      L->top = res + 1;
+        setobjs2s(L, res, L->top.p - nres);  /* move it to proper place */
+      L->top.p = res + 1;
       return;
     case LUA_MULTRET:
       wanted = nres;  /* we want all results */
@@ -446,14 +445,14 @@ l_sinline void moveresults (lua_State *L, StkId res, int nres, int wanted) {
       break;
   }
   /* generic case */
-  firstresult = L->top - nres;  /* index of first result */
+  firstresult = L->top.p - nres;  /* index of first result */
   if (nres > wanted)  /* extra results? */
     nres = wanted;  /* don't need them */
   for (i = 0; i < nres; i++)  /* move all results to correct place */
     setobjs2s(L, res + i, firstresult + i);
   for (; i < wanted; i++)  /* complete wanted number of results */
     setnilvalue(s2v(res + i));
-  L->top = res + wanted;  /* top points after the last result */
+  L->top.p = res + wanted;  /* top points after the last result */
 }
 
 
@@ -468,7 +467,7 @@ void luaD_poscall (lua_State *L, CallInfo *ci, int nres) {
   if (l_unlikely(L->hookmask && !hastocloseCfunc(wanted)))
     rethook(L, ci, nres);
   /* move results to proper place */
-  moveresults(L, ci->func, nres, wanted);
+  moveresults(L, ci->func.p, nres, wanted);
   /* function cannot be in any of these cases when returning */
   lua_assert(!(ci->callstatus &
         (CIST_HOOKED | CIST_YPCALL | CIST_FIN | CIST_TRAN | CIST_CLSRET)));
@@ -483,10 +482,10 @@ void luaD_poscall (lua_State *L, CallInfo *ci, int nres) {
 l_sinline CallInfo *prepCallInfo (lua_State *L, StkId func, int nret,
                                                 int mask, StkId top) {
   CallInfo *ci = L->ci = next_ci(L);  /* new frame */
-  ci->func = func;
+  ci->func.p = func;
   ci->nresults = nret;
   ci->callstatus = mask;
-  ci->top = top;
+  ci->top.p = top;
   return ci;
 }
 
@@ -500,10 +499,10 @@ l_sinline int precallC (lua_State *L, StkId func, int nresults,
   CallInfo *ci;
   checkstackGCp(L, LUA_MINSTACK, func);  /* ensure minimum stack size */
   L->ci = ci = prepCallInfo(L, func, nresults, CIST_C,
-                               L->top + LUA_MINSTACK);
-  lua_assert(ci->top <= L->stack_last);
+                               L->top.p + LUA_MINSTACK);
+  lua_assert(ci->top.p <= L->stack_last.p);
   if (l_unlikely(L->hookmask & LUA_MASKCALL)) {
-    int narg = cast_int(L->top - func) - 1;
+    int narg = cast_int(L->top.p - func) - 1;
     luaD_hook(L, LUA_HOOKCALL, -1, 1, narg);
   }
   lua_unlock(L);
@@ -535,17 +534,17 @@ int luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func,
       int nfixparams = p->numparams;
       int i;
       checkstackGCp(L, fsize - delta, func);
-      ci->func -= delta;  /* restore 'func' (if vararg) */
+      ci->func.p -= delta;  /* restore 'func' (if vararg) */
       for (i = 0; i < narg1; i++)  /* move down function and arguments */
-        setobjs2s(L, ci->func + i, func + i);
-      func = ci->func;  /* moved-down function */
+        setobjs2s(L, ci->func.p + i, func + i);
+      func = ci->func.p;  /* moved-down function */
       for (; narg1 <= nfixparams; narg1++)
         setnilvalue(s2v(func + narg1));  /* complete missing arguments */
-      ci->top = func + 1 + fsize;  /* top for new function */
-      lua_assert(ci->top <= L->stack_last);
+      ci->top.p = func + 1 + fsize;  /* top for new function */
+      lua_assert(ci->top.p <= L->stack_last.p);
       ci->u.l.savedpc = p->code;  /* starting point */
       ci->callstatus |= CIST_TAIL;
-      L->top = func + narg1;  /* set top */
+      L->top.p = func + narg1;  /* set top */
       return -1;
     }
     default: {  /* not a function */
@@ -578,15 +577,15 @@ CallInfo *luaD_precall (lua_State *L, StkId func, int nresults) {
     case LUA_VLCL: {  /* Lua function */
       CallInfo *ci;
       Proto *p = clLvalue(s2v(func))->p;
-      int narg = cast_int(L->top - func) - 1;  /* number of real arguments */
+      int narg = cast_int(L->top.p - func) - 1;  /* number of real arguments */
       int nfixparams = p->numparams;
       int fsize = p->maxstacksize;  /* frame size */
       checkstackGCp(L, fsize, func);
       L->ci = ci = prepCallInfo(L, func, nresults, 0, func + 1 + fsize);
       ci->u.l.savedpc = p->code;  /* starting point */
       for (; narg < nfixparams; narg++)
-        setnilvalue(s2v(L->top++));  /* complete missing arguments */
-      lua_assert(ci->top <= L->stack_last);
+        setnilvalue(s2v(L->top.p++));  /* complete missing arguments */
+      lua_assert(ci->top.p <= L->stack_last.p);
       return ci;
     }
     default: {  /* not a function */
@@ -748,8 +747,8 @@ static CallInfo *findpcall (lua_State *L) {
 ** coroutine error handler and should not kill the coroutine.)
 */
 static int resume_error (lua_State *L, const char *msg, int narg) {
-  L->top -= narg;  /* remove args from the stack */
-  setsvalue2s(L, L->top, luaS_new(L, msg));  /* push error message */
+  L->top.p -= narg;  /* remove args from the stack */
+  setsvalue2s(L, L->top.p, luaS_new(L, msg));  /* push error message */
   api_incr_top(L);
   lua_unlock(L);
   return LUA_ERRRUN;
@@ -765,7 +764,7 @@ static int resume_error (lua_State *L, const char *msg, int narg) {
 */
 static void resume (lua_State *L, void *ud) {
   int n = *(cast(int*, ud));  /* number of arguments */
-  StkId firstArg = L->top - n;  /* first argument */
+  StkId firstArg = L->top.p - n;  /* first argument */
   CallInfo *ci = L->ci;
   if (L->status == LUA_OK)  /* starting a coroutine? */
     ccall(L, firstArg - 1, LUA_MULTRET, 0);  /* just call its body */
@@ -773,7 +772,7 @@ static void resume (lua_State *L, void *ud) {
     lua_assert(L->status == LUA_YIELD);
     L->status = LUA_OK;  /* mark that it is running (again) */
     if (isLua(ci)) {  /* yielded inside a hook? */
-      L->top = firstArg;  /* discard arguments */
+      L->top.p = firstArg;  /* discard arguments */
       luaV_execute(L, ci);  /* just continue running Lua code */
     }
     else {  /* 'common' yield */
@@ -816,7 +815,7 @@ LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
   if (L->status == LUA_OK) {  /* may be starting a coroutine */
     if (L->ci != &L->base_ci)  /* not in base level? */
       return resume_error(L, "cannot resume non-suspended coroutine", nargs);
-    else if (L->top - (L->ci->func + 1) == nargs)  /* no function? */
+    else if (L->top.p - (L->ci->func.p + 1) == nargs)  /* no function? */
       return resume_error(L, "cannot resume dead coroutine", nargs);
   }
   else if (L->status != LUA_YIELD)  /* ended with errors? */
@@ -834,11 +833,11 @@ LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
     lua_assert(status == L->status);  /* normal end or yield */
   else {  /* unrecoverable error */
     L->status = cast_byte(status);  /* mark thread as 'dead' */
-    luaD_seterrorobj(L, status, L->top);  /* push error message */
-    L->ci->top = L->top;
+    luaD_seterrorobj(L, status, L->top.p);  /* push error message */
+    L->ci->top.p = L->top.p;
   }
   *nresults = (status == LUA_YIELD) ? L->ci->u2.nyield
-                                    : cast_int(L->top - (L->ci->func + 1));
+                                    : cast_int(L->top.p - (L->ci->func.p + 1));
   lua_unlock(L);
   return status;
 }
@@ -993,7 +992,7 @@ int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
   p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
   p.dyd.label.arr = NULL; p.dyd.label.size = 0;
   luaZ_initbuffer(L, &p.buff);
-  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
+  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top.p), L->errfunc);
   luaZ_freebuffer(L, &p.buff);
   luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
   luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
diff --git a/ldo.h b/ldo.h
index 4661aa00..1aa446ad 100644
--- a/ldo.h
+++ b/ldo.h
@@ -8,6 +8,7 @@
 #define ldo_h
 
 
+#include "llimits.h"
 #include "lobject.h"
 #include "lstate.h"
 #include "lzio.h"
@@ -23,7 +24,7 @@
 ** at every check.
 */
 #define luaD_checkstackaux(L,n,pre,pos)  \
-	if (l_unlikely(L->stack_last - L->top <= (n))) \
+	if (l_unlikely(L->stack_last.p - L->top.p <= (n))) \
 	  { pre; luaD_growstack(L, n, 1); pos; } \
         else { condmovestack(L,pre,pos); }
 
@@ -32,8 +33,8 @@
 
 
 
-#define savestack(L,p)		((char *)(p) - (char *)L->stack)
-#define restorestack(L,n)	((StkId)((char *)L->stack + (n)))
+#define savestack(L,pt)		(cast_charp(pt) - cast_charp(L->stack.p))
+#define restorestack(L,n)	cast(StkId, cast_charp(L->stack.p) + (n))
 
 
 /* macro to check stack size, preserving 'p' */
diff --git a/lfunc.c b/lfunc.c
index daba0abf..804bf9dc 100644
--- a/lfunc.c
+++ b/lfunc.c
@@ -50,8 +50,8 @@ void luaF_initupvals (lua_State *L, LClosure *cl) {
   for (i = 0; i < cl->nupvalues; i++) {
     GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));
     UpVal *uv = gco2upv(o);
-    uv->v = &uv->u.value;  /* make it closed */
-    setnilvalue(uv->v);
+    uv->v.p = &uv->u.value;  /* make it closed */
+    setnilvalue(uv->v.p);
     cl->upvals[i] = uv;
     luaC_objbarrier(L, cl, uv);
   }
@@ -66,7 +66,7 @@ static UpVal *newupval (lua_State *L, int tbc, StkId level, UpVal **prev) {
   GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));
   UpVal *uv = gco2upv(o);
   UpVal *next = *prev;
-  uv->v = s2v(level);  /* current value lives in the stack */
+  uv->v.p = s2v(level);  /* current value lives in the stack */
   uv->tbc = tbc;
   uv->u.open.next = next;  /* link it to list of open upvalues */
   uv->u.open.previous = prev;
@@ -106,12 +106,12 @@ UpVal *luaF_findupval (lua_State *L, StkId level) {
 ** (This function assumes EXTRA_STACK.)
 */
 static void callclosemethod (lua_State *L, TValue *obj, TValue *err, int yy) {
-  StkId top = L->top;
+  StkId top = L->top.p;
   const TValue *tm = luaT_gettmbyobj(L, obj, TM_CLOSE);
   setobj2s(L, top, tm);  /* will call metamethod... */
   setobj2s(L, top + 1, obj);  /* with 'self' as the 1st argument */
   setobj2s(L, top + 2, err);  /* and error msg. as 2nd argument */
-  L->top = top + 3;  /* add function and arguments */
+  L->top.p = top + 3;  /* add function and arguments */
   if (yy)
     luaD_call(L, top, 0);
   else
@@ -126,7 +126,7 @@ static void callclosemethod (lua_State *L, TValue *obj, TValue *err, int yy) {
 static void checkclosemth (lua_State *L, StkId level) {
   const TValue *tm = luaT_gettmbyobj(L, s2v(level), TM_CLOSE);
   if (ttisnil(tm)) {  /* no metamethod? */
-    int idx = cast_int(level - L->ci->func);  /* variable index */
+    int idx = cast_int(level - L->ci->func.p);  /* variable index */
     const char *vname = luaG_findlocal(L, L->ci, idx, NULL);
     if (vname == NULL) vname = "?";
     luaG_runerror(L, "variable '%s' got a non-closable value", vname);
@@ -160,23 +160,23 @@ static void prepcallclosemth (lua_State *L, StkId level, int status, int yy) {
 ** is used.)
 */
 #define MAXDELTA  \
-	((256ul << ((sizeof(L->stack->tbclist.delta) - 1) * 8)) - 1)
+	((256ul << ((sizeof(L->stack.p->tbclist.delta) - 1) * 8)) - 1)
 
 
 /*
 ** Insert a variable in the list of to-be-closed variables.
 */
 void luaF_newtbcupval (lua_State *L, StkId level) {
-  lua_assert(level > L->tbclist);
+  lua_assert(level > L->tbclist.p);
   if (l_isfalse(s2v(level)))
     return;  /* false doesn't need to be closed */
   checkclosemth(L, level);  /* value must have a close method */
-  while (cast_uint(level - L->tbclist) > MAXDELTA) {
-    L->tbclist += MAXDELTA;  /* create a dummy node at maximum delta */
-    L->tbclist->tbclist.delta = 0;
+  while (cast_uint(level - L->tbclist.p) > MAXDELTA) {
+    L->tbclist.p += MAXDELTA;  /* create a dummy node at maximum delta */
+    L->tbclist.p->tbclist.delta = 0;
   }
-  level->tbclist.delta = cast(unsigned short, level - L->tbclist);
-  L->tbclist = level;
+  level->tbclist.delta = cast(unsigned short, level - L->tbclist.p);
+  L->tbclist.p = level;
 }
 
 
@@ -196,10 +196,10 @@ void luaF_closeupval (lua_State *L, StkId level) {
   StkId upl;  /* stack index pointed by 'uv' */
   while ((uv = L->openupval) != NULL && (upl = uplevel(uv)) >= level) {
     TValue *slot = &uv->u.value;  /* new position for value */
-    lua_assert(uplevel(uv) < L->top);
+    lua_assert(uplevel(uv) < L->top.p);
     luaF_unlinkupval(uv);  /* remove upvalue from 'openupval' list */
-    setobj(L, slot, uv->v);  /* move value to upvalue slot */
-    uv->v = slot;  /* now current value lives here */
+    setobj(L, slot, uv->v.p);  /* move value to upvalue slot */
+    uv->v.p = slot;  /* now current value lives here */
     if (!iswhite(uv)) {  /* neither white nor dead? */
       nw2black(uv);  /* closed upvalues cannot be gray */
       luaC_barrier(L, uv, slot);
@@ -212,12 +212,12 @@ void luaF_closeupval (lua_State *L, StkId level) {
 ** Remove first element from the tbclist plus its dummy nodes.
 */
 static void poptbclist (lua_State *L) {
-  StkId tbc = L->tbclist;
+  StkId tbc = L->tbclist.p;
   lua_assert(tbc->tbclist.delta > 0);  /* first element cannot be dummy */
   tbc -= tbc->tbclist.delta;
-  while (tbc > L->stack && tbc->tbclist.delta == 0)
+  while (tbc > L->stack.p && tbc->tbclist.delta == 0)
     tbc -= MAXDELTA;  /* remove dummy nodes */
-  L->tbclist = tbc;
+  L->tbclist.p = tbc;
 }
 
 
@@ -228,8 +228,8 @@ static void poptbclist (lua_State *L) {
 StkId luaF_close (lua_State *L, StkId level, int status, int yy) {
   ptrdiff_t levelrel = savestack(L, level);
   luaF_closeupval(L, level);  /* first, close the upvalues */
-  while (L->tbclist >= level) {  /* traverse tbc's down to that level */
-    StkId tbc = L->tbclist;  /* get variable index */
+  while (L->tbclist.p >= level) {  /* traverse tbc's down to that level */
+    StkId tbc = L->tbclist.p;  /* get variable index */
     poptbclist(L);  /* remove it from list */
     prepcallclosemth(L, tbc, status, yy);  /* close variable */
     level = restorestack(L, levelrel);
diff --git a/lfunc.h b/lfunc.h
index 3d296971..3be265ef 100644
--- a/lfunc.h
+++ b/lfunc.h
@@ -29,10 +29,10 @@
 #define MAXUPVAL	255
 
 
-#define upisopen(up)	((up)->v != &(up)->u.value)
+#define upisopen(up)	((up)->v.p != &(up)->u.value)
 
 
-#define uplevel(up)	check_exp(upisopen(up), cast(StkId, (up)->v))
+#define uplevel(up)	check_exp(upisopen(up), cast(StkId, (up)->v.p))
 
 
 /*
diff --git a/lgc.c b/lgc.c
index 317ea450..8e76ccd7 100644
--- a/lgc.c
+++ b/lgc.c
@@ -301,7 +301,7 @@ static void reallymarkobject (global_State *g, GCObject *o) {
         set2gray(uv);  /* open upvalues are kept gray */
       else
         set2black(uv);  /* closed upvalues are visited here */
-      markvalue(g, uv->v);  /* mark its content */
+      markvalue(g, uv->v.p);  /* mark its content */
       break;
     }
     case LUA_VUSERDATA: {
@@ -376,7 +376,7 @@ static int remarkupvals (global_State *g) {
         work++;
         if (!iswhite(uv)) {  /* upvalue already visited? */
           lua_assert(upisopen(uv) && isgray(uv));
-          markvalue(g, uv->v);  /* mark its value */
+          markvalue(g, uv->v.p);  /* mark its value */
         }
       }
     }
@@ -620,19 +620,19 @@ static int traverseLclosure (global_State *g, LClosure *cl) {
 */
 static int traversethread (global_State *g, lua_State *th) {
   UpVal *uv;
-  StkId o = th->stack;
+  StkId o = th->stack.p;
   if (isold(th) || g->gcstate == GCSpropagate)
     linkgclist(th, g->grayagain);  /* insert into 'grayagain' list */
   if (o == NULL)
     return 1;  /* stack not completely built yet */
   lua_assert(g->gcstate == GCSatomic ||
              th->openupval == NULL || isintwups(th));
-  for (; o < th->top; o++)  /* mark live elements in the stack */
+  for (; o < th->top.p; o++)  /* mark live elements in the stack */
     markvalue(g, s2v(o));
   for (uv = th->openupval; uv != NULL; uv = uv->u.open.next)
     markobject(g, uv);  /* open upvalues cannot be collected */
   if (g->gcstate == GCSatomic) {  /* final traversal? */
-    for (; o < th->stack_last + EXTRA_STACK; o++)
+    for (; o < th->stack_last.p + EXTRA_STACK; o++)
       setnilvalue(s2v(o));  /* clear dead stack slice */
     /* 'remarkupvals' may have removed thread from 'twups' list */
     if (!isintwups(th) && th->openupval != NULL) {
@@ -892,7 +892,7 @@ static GCObject *udata2finalize (global_State *g) {
 
 static void dothecall (lua_State *L, void *ud) {
   UNUSED(ud);
-  luaD_callnoyield(L, L->top - 2, 0);
+  luaD_callnoyield(L, L->top.p - 2, 0);
 }
 
 
@@ -909,16 +909,16 @@ static void GCTM (lua_State *L) {
     int oldgcstp  = g->gcstp;
     g->gcstp |= GCSTPGC;  /* avoid GC steps */
     L->allowhook = 0;  /* stop debug hooks during GC metamethod */
-    setobj2s(L, L->top++, tm);  /* push finalizer... */
-    setobj2s(L, L->top++, &v);  /* ... and its argument */
+    setobj2s(L, L->top.p++, tm);  /* push finalizer... */
+    setobj2s(L, L->top.p++, &v);  /* ... and its argument */
     L->ci->callstatus |= CIST_FIN;  /* will run a finalizer */
-    status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
+    status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top.p - 2), 0);
     L->ci->callstatus &= ~CIST_FIN;  /* not running a finalizer anymore */
     L->allowhook = oldah;  /* restore hooks */
     g->gcstp = oldgcstp;  /* restore state */
     if (l_unlikely(status != LUA_OK)) {  /* error while running __gc? */
       luaE_warnerror(L, "__gc");
-      L->top--;  /* pops error object */
+      L->top.p--;  /* pops error object */
     }
   }
 }
diff --git a/llex.c b/llex.c
index e9915178..b0dc0acc 100644
--- a/llex.c
+++ b/llex.c
@@ -138,12 +138,12 @@ TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
   if (!ttisnil(o))  /* string already present? */
     ts = keystrval(nodefromval(o));  /* get saved copy */
   else {  /* not in use yet */
-    TValue *stv = s2v(L->top++);  /* reserve stack space for string */
+    TValue *stv = s2v(L->top.p++);  /* reserve stack space for string */
     setsvalue(L, stv, ts);  /* temporarily anchor the string */
     luaH_finishset(L, ls->h, stv, o, stv);  /* t[string] = string */
     /* table is not a metatable, so it does not need to invalidate cache */
     luaC_checkGC(L);
-    L->top--;  /* remove string from stack */
+    L->top.p--;  /* remove string from stack */
   }
   return ts;
 }
diff --git a/lobject.c b/lobject.c
index 03e2798c..f73ffc6d 100644
--- a/lobject.c
+++ b/lobject.c
@@ -413,8 +413,8 @@ typedef struct BuffFS {
 */
 static void pushstr (BuffFS *buff, const char *str, size_t lstr) {
   lua_State *L = buff->L;
-  setsvalue2s(L, L->top, luaS_newlstr(L, str, lstr));
-  L->top++;  /* may use one slot from EXTRA_STACK */
+  setsvalue2s(L, L->top.p, luaS_newlstr(L, str, lstr));
+  L->top.p++;  /* may use one slot from EXTRA_STACK */
   if (!buff->pushed)  /* no previous string on the stack? */
     buff->pushed = 1;  /* now there is one */
   else  /* join previous string with new one */
@@ -542,7 +542,7 @@ const char *luaO_pushvfstring (lua_State *L, const char *fmt, va_list argp) {
   addstr2buff(&buff, fmt, strlen(fmt));  /* rest of 'fmt' */
   clearbuff(&buff);  /* empty buffer into the stack */
   lua_assert(buff.pushed == 1);
-  return svalue(s2v(L->top - 1));
+  return svalue(s2v(L->top.p - 1));
 }
 
 
diff --git a/lobject.h b/lobject.h
index 77cc606f..7af7bd89 100644
--- a/lobject.h
+++ b/lobject.h
@@ -157,6 +157,12 @@ typedef union StackValue {
 /* index to stack elements */
 typedef StackValue *StkId;
 
+
+typedef union {
+  StkId p;  /* actual pointer */
+} StkIdRel;
+
+
 /* convert a 'StackValue' to a 'TValue' */
 #define s2v(o)	(&(o)->val)
 
@@ -618,7 +624,9 @@ typedef struct Proto {
 typedef struct UpVal {
   CommonHeader;
   lu_byte tbc;  /* true if it represents a to-be-closed variable */
-  TValue *v;  /* points to stack or to its own value */
+  union {
+    TValue *p;  /* points to stack or to its own value */
+  } v;
   union {
     struct {  /* (when open) */
       struct UpVal *next;  /* linked list */
diff --git a/lparser.c b/lparser.c
index fe693b57..24668c24 100644
--- a/lparser.c
+++ b/lparser.c
@@ -1944,10 +1944,10 @@ LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
   LexState lexstate;
   FuncState funcstate;
   LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
-  setclLvalue2s(L, L->top, cl);  /* anchor it (to avoid being collected) */
+  setclLvalue2s(L, L->top.p, cl);  /* anchor it (to avoid being collected) */
   luaD_inctop(L);
   lexstate.h = luaH_new(L);  /* create table for scanner */
-  sethvalue2s(L, L->top, lexstate.h);  /* anchor it */
+  sethvalue2s(L, L->top.p, lexstate.h);  /* anchor it */
   luaD_inctop(L);
   funcstate.f = cl->p = luaF_newproto(L);
   luaC_objbarrier(L, cl, cl->p);
@@ -1961,7 +1961,7 @@ LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
   /* all scopes should be correctly finished */
   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
-  L->top--;  /* remove scanner's table */
+  L->top.p--;  /* remove scanner's table */
   return cl;  /* closure is on the stack, too */
 }
 
diff --git a/lstate.c b/lstate.c
index 4b5c1000..c63fe867 100644
--- a/lstate.c
+++ b/lstate.c
@@ -180,33 +180,33 @@ LUAI_FUNC void luaE_incCstack (lua_State *L) {
 static void stack_init (lua_State *L1, lua_State *L) {
   int i; CallInfo *ci;
   /* initialize stack array */
-  L1->stack = luaM_newvector(L, BASIC_STACK_SIZE + EXTRA_STACK, StackValue);
-  L1->tbclist = L1->stack;
+  L1->stack.p = luaM_newvector(L, BASIC_STACK_SIZE + EXTRA_STACK, StackValue);
+  L1->tbclist.p = L1->stack.p;
   for (i = 0; i < BASIC_STACK_SIZE + EXTRA_STACK; i++)
-    setnilvalue(s2v(L1->stack + i));  /* erase new stack */
-  L1->top = L1->stack;
-  L1->stack_last = L1->stack + BASIC_STACK_SIZE;
+    setnilvalue(s2v(L1->stack.p + i));  /* erase new stack */
+  L1->top.p = L1->stack.p;
+  L1->stack_last.p = L1->stack.p + BASIC_STACK_SIZE;
   /* initialize first ci */
   ci = &L1->base_ci;
   ci->next = ci->previous = NULL;
   ci->callstatus = CIST_C;
-  ci->func = L1->top;
+  ci->func.p = L1->top.p;
   ci->u.c.k = NULL;
   ci->nresults = 0;
-  setnilvalue(s2v(L1->top));  /* 'function' entry for this 'ci' */
-  L1->top++;
-  ci->top = L1->top + LUA_MINSTACK;
+  setnilvalue(s2v(L1->top.p));  /* 'function' entry for this 'ci' */
+  L1->top.p++;
+  ci->top.p = L1->top.p + LUA_MINSTACK;
   L1->ci = ci;
 }
 
 
 static void freestack (lua_State *L) {
-  if (L->stack == NULL)
+  if (L->stack.p == NULL)
     return;  /* stack not completely built yet */
   L->ci = &L->base_ci;  /* free the entire 'ci' list */
   luaE_freeCI(L);
   lua_assert(L->nci == 0);
-  luaM_freearray(L, L->stack, stacksize(L) + EXTRA_STACK);  /* free stack */
+  luaM_freearray(L, L->stack.p, stacksize(L) + EXTRA_STACK);  /* free stack */
 }
 
 
@@ -248,7 +248,7 @@ static void f_luaopen (lua_State *L, void *ud) {
 */
 static void preinit_thread (lua_State *L, global_State *g) {
   G(L) = g;
-  L->stack = NULL;
+  L->stack.p = NULL;
   L->ci = NULL;
   L->nci = 0;
   L->twups = L;  /* thread has no upvalues */
@@ -297,7 +297,7 @@ LUA_API lua_State *lua_newthread (lua_State *L) {
   L1->next = g->allgc;
   g->allgc = obj2gco(L1);
   /* anchor it on L stack */
-  setthvalue2s(L, L->top, L1);
+  setthvalue2s(L, L->top.p, L1);
   api_incr_top(L);
   preinit_thread(L1, g);
   L1->hookmask = L->hookmask;
@@ -316,7 +316,7 @@ LUA_API lua_State *lua_newthread (lua_State *L) {
 
 void luaE_freethread (lua_State *L, lua_State *L1) {
   LX *l = fromstate(L1);
-  luaF_closeupval(L1, L1->stack);  /* close all upvalues */
+  luaF_closeupval(L1, L1->stack.p);  /* close all upvalues */
   lua_assert(L1->openupval == NULL);
   luai_userstatefree(L, L1);
   freestack(L1);
@@ -326,19 +326,19 @@ void luaE_freethread (lua_State *L, lua_State *L1) {
 
 int luaE_resetthread (lua_State *L, int status) {
   CallInfo *ci = L->ci = &L->base_ci;  /* unwind CallInfo list */
-  setnilvalue(s2v(L->stack));  /* 'function' entry for basic 'ci' */
-  ci->func = L->stack;
+  setnilvalue(s2v(L->stack.p));  /* 'function' entry for basic 'ci' */
+  ci->func.p = L->stack.p;
   ci->callstatus = CIST_C;
   if (status == LUA_YIELD)
     status = LUA_OK;
   L->status = LUA_OK;  /* so it can run __close metamethods */
   status = luaD_closeprotected(L, 1, status);
   if (status != LUA_OK)  /* errors? */
-    luaD_seterrorobj(L, status, L->stack + 1);
+    luaD_seterrorobj(L, status, L->stack.p + 1);
   else
-    L->top = L->stack + 1;
-  ci->top = L->top + LUA_MINSTACK;
-  luaD_reallocstack(L, cast_int(ci->top - L->stack), 0);
+    L->top.p = L->stack.p + 1;
+  ci->top.p = L->top.p + LUA_MINSTACK;
+  luaD_reallocstack(L, cast_int(ci->top.p - L->stack.p), 0);
   return status;
 }
 
@@ -427,7 +427,7 @@ void luaE_warning (lua_State *L, const char *msg, int tocont) {
 ** Generate a warning from an error message
 */
 void luaE_warnerror (lua_State *L, const char *where) {
-  TValue *errobj = s2v(L->top - 1);  /* error object */
+  TValue *errobj = s2v(L->top.p - 1);  /* error object */
   const char *msg = (ttisstring(errobj))
                   ? svalue(errobj)
                   : "error object is not a string";
diff --git a/lstate.h b/lstate.h
index 61e82cde..2e907818 100644
--- a/lstate.h
+++ b/lstate.h
@@ -139,7 +139,7 @@ struct lua_longjmp;  /* defined in ldo.c */
 
 #define BASIC_STACK_SIZE        (2*LUA_MINSTACK)
 
-#define stacksize(th)	cast_int((th)->stack_last - (th)->stack)
+#define stacksize(th)	cast_int((th)->stack_last.p - (th)->stack.p)
 
 
 /* kinds of Garbage Collection */
@@ -170,8 +170,8 @@ typedef struct stringtable {
 ** before the function starts or after it ends.
 */
 typedef struct CallInfo {
-  StkId func;  /* function index in the stack */
-  StkId	top;  /* top for this function */
+  StkIdRel func;  /* function index in the stack */
+  StkIdRel	top;  /* top for this function */
   struct CallInfo *previous, *next;  /* dynamic call link */
   union {
     struct {  /* only for Lua functions */
@@ -306,13 +306,13 @@ struct lua_State {
   lu_byte status;
   lu_byte allowhook;
   unsigned short nci;  /* number of items in 'ci' list */
-  StkId top;  /* first free slot in the stack */
+  StkIdRel top;  /* first free slot in the stack */
   global_State *l_G;
   CallInfo *ci;  /* call info for current function */
-  StkId stack_last;  /* end of stack (last element + 1) */
-  StkId stack;  /* stack base */
+  StkIdRel stack_last;  /* end of stack (last element + 1) */
+  StkIdRel stack;  /* stack base */
   UpVal *openupval;  /* list of open upvalues in this stack */
-  StkId tbclist;  /* list of to-be-closed variables */
+  StkIdRel tbclist;  /* list of to-be-closed variables */
   GCObject *gclist;
   struct lua_State *twups;  /* list of threads with open upvalues */
   struct lua_longjmp *errorJmp;  /* current error recover point */
diff --git a/ltests.c b/ltests.c
index 734a96da..4a0a6af1 100644
--- a/ltests.c
+++ b/ltests.c
@@ -44,7 +44,7 @@
 void *l_Trick = 0;
 
 
-#define obj_at(L,k)	s2v(L->ci->func + (k))
+#define obj_at(L,k)	s2v(L->ci->func.p + (k))
 
 
 static int runC (lua_State *L, lua_State *L1, const char *pc);
@@ -57,7 +57,7 @@ static void setnameval (lua_State *L, const char *name, int val) {
 
 
 static void pushobject (lua_State *L, const TValue *o) {
-  setobj2s(L, L->top, o);
+  setobj2s(L, L->top.p, o);
   api_incr_top(L);
 }
 
@@ -419,7 +419,7 @@ static void checkLclosure (global_State *g, LClosure *cl) {
     if (uv) {
       checkobjrefN(g, clgc, uv);
       if (!upisopen(uv))
-        checkvalref(g, obj2gco(uv), uv->v);
+        checkvalref(g, obj2gco(uv), uv->v.p);
     }
   }
 }
@@ -428,7 +428,7 @@ static void checkLclosure (global_State *g, LClosure *cl) {
 static int lua_checkpc (CallInfo *ci) {
   if (!isLua(ci)) return 1;
   else {
-    StkId f = ci->func;
+    StkId f = ci->func.p;
     Proto *p = clLvalue(s2v(f))->p;
     return p->code <= ci->u.l.savedpc &&
            ci->u.l.savedpc <= p->code + p->sizecode;
@@ -441,19 +441,19 @@ static void checkstack (global_State *g, lua_State *L1) {
   CallInfo *ci;
   UpVal *uv;
   assert(!isdead(g, L1));
-  if (L1->stack == NULL) {  /* incomplete thread? */
+  if (L1->stack.p == NULL) {  /* incomplete thread? */
     assert(L1->openupval == NULL && L1->ci == NULL);
     return;
   }
   for (uv = L1->openupval; uv != NULL; uv = uv->u.open.next)
     assert(upisopen(uv));  /* must be open */
-  assert(L1->top <= L1->stack_last);
-  assert(L1->tbclist <= L1->top);
+  assert(L1->top.p <= L1->stack_last.p);
+  assert(L1->tbclist.p <= L1->top.p);
   for (ci = L1->ci; ci != NULL; ci = ci->previous) {
-    assert(ci->top <= L1->stack_last);
+    assert(ci->top.p <= L1->stack_last.p);
     assert(lua_checkpc(ci));
   }
-  for (o = L1->stack; o < L1->stack_last; o++)
+  for (o = L1->stack.p; o < L1->stack_last.p; o++)
     checkliveness(L1, s2v(o));  /* entire stack must have valid values */
 }
 
@@ -465,7 +465,7 @@ static void checkrefs (global_State *g, GCObject *o) {
       break;
     }
     case LUA_VUPVAL: {
-      checkvalref(g, o, gco2upv(o)->v);
+      checkvalref(g, o, gco2upv(o)->v.p);
       break;
     }
     case LUA_VTABLE: {
@@ -980,7 +980,7 @@ static int hash_query (lua_State *L) {
 
 static int stacklevel (lua_State *L) {
   unsigned long a = 0;
-  lua_pushinteger(L, (L->top - L->stack));
+  lua_pushinteger(L, (L->top.p - L->stack.p));
   lua_pushinteger(L, stacksize(L));
   lua_pushinteger(L, L->nCcalls);
   lua_pushinteger(L, L->nci);
@@ -1040,7 +1040,7 @@ static int string_query (lua_State *L) {
     TString *ts;
     int n = 0;
     for (ts = tb->hash[s]; ts != NULL; ts = ts->u.hnext) {
-      setsvalue2s(L, L->top, ts);
+      setsvalue2s(L, L->top.p, ts);
       api_incr_top(L);
       n++;
     }
diff --git a/ltm.c b/ltm.c
index b657b783..07a06081 100644
--- a/ltm.c
+++ b/ltm.c
@@ -102,12 +102,12 @@ const char *luaT_objtypename (lua_State *L, const TValue *o) {
 
 void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
                   const TValue *p2, const TValue *p3) {
-  StkId func = L->top;
+  StkId func = L->top.p;
   setobj2s(L, func, f);  /* push function (assume EXTRA_STACK) */
   setobj2s(L, func + 1, p1);  /* 1st argument */
   setobj2s(L, func + 2, p2);  /* 2nd argument */
   setobj2s(L, func + 3, p3);  /* 3rd argument */
-  L->top = func + 4;
+  L->top.p = func + 4;
   /* metamethod may yield only when called from Lua code */
   if (isLuacode(L->ci))
     luaD_call(L, func, 0);
@@ -119,18 +119,18 @@ void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
 void luaT_callTMres (lua_State *L, const TValue *f, const TValue *p1,
                      const TValue *p2, StkId res) {
   ptrdiff_t result = savestack(L, res);
-  StkId func = L->top;
+  StkId func = L->top.p;
   setobj2s(L, func, f);  /* push function (assume EXTRA_STACK) */
   setobj2s(L, func + 1, p1);  /* 1st argument */
   setobj2s(L, func + 2, p2);  /* 2nd argument */
-  L->top += 3;
+  L->top.p += 3;
   /* metamethod may yield only when called from Lua code */
   if (isLuacode(L->ci))
     luaD_call(L, func, 1);
   else
     luaD_callnoyield(L, func, 1);
   res = restorestack(L, result);
-  setobjs2s(L, res, --L->top);  /* move result to its place */
+  setobjs2s(L, res, --L->top.p);  /* move result to its place */
 }
 
 
@@ -165,7 +165,7 @@ void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
 
 
 void luaT_tryconcatTM (lua_State *L) {
-  StkId top = L->top;
+  StkId top = L->top.p;
   if (l_unlikely(!callbinTM(L, s2v(top - 2), s2v(top - 1), top - 2,
                                TM_CONCAT)))
     luaG_concaterror(L, s2v(top - 2), s2v(top - 1));
@@ -200,15 +200,15 @@ void luaT_trybiniTM (lua_State *L, const TValue *p1, lua_Integer i2,
 */
 int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
                       TMS event) {
-  if (callbinTM(L, p1, p2, L->top, event))  /* try original event */
-    return !l_isfalse(s2v(L->top));
+  if (callbinTM(L, p1, p2, L->top.p, event))  /* try original event */
+    return !l_isfalse(s2v(L->top.p));
 #if defined(LUA_COMPAT_LT_LE)
   else if (event == TM_LE) {
       /* try '!(p2 < p1)' for '(p1 <= p2)' */
       L->ci->callstatus |= CIST_LEQ;  /* mark it is doing 'lt' for 'le' */
-      if (callbinTM(L, p2, p1, L->top, TM_LT)) {
+      if (callbinTM(L, p2, p1, L->top.p, TM_LT)) {
         L->ci->callstatus ^= CIST_LEQ;  /* clear mark */
-        return l_isfalse(s2v(L->top));
+        return l_isfalse(s2v(L->top.p));
       }
       /* else error will remove this 'ci'; no need to clear mark */
   }
@@ -238,20 +238,20 @@ int luaT_callorderiTM (lua_State *L, const TValue *p1, int v2,
 void luaT_adjustvarargs (lua_State *L, int nfixparams, CallInfo *ci,
                          const Proto *p) {
   int i;
-  int actual = cast_int(L->top - ci->func) - 1;  /* number of arguments */
+  int actual = cast_int(L->top.p - ci->func.p) - 1;  /* number of arguments */
   int nextra = actual - nfixparams;  /* number of extra arguments */
   ci->u.l.nextraargs = nextra;
   luaD_checkstack(L, p->maxstacksize + 1);
   /* copy function to the top of the stack */
-  setobjs2s(L, L->top++, ci->func);
+  setobjs2s(L, L->top.p++, ci->func.p);
   /* move fixed parameters to the top of the stack */
   for (i = 1; i <= nfixparams; i++) {
-    setobjs2s(L, L->top++, ci->func + i);
-    setnilvalue(s2v(ci->func + i));  /* erase original parameter (for GC) */
+    setobjs2s(L, L->top.p++, ci->func.p + i);
+    setnilvalue(s2v(ci->func.p + i));  /* erase original parameter (for GC) */
   }
-  ci->func += actual + 1;
-  ci->top += actual + 1;
-  lua_assert(L->top <= ci->top && ci->top <= L->stack_last);
+  ci->func.p += actual + 1;
+  ci->top.p += actual + 1;
+  lua_assert(L->top.p <= ci->top.p && ci->top.p <= L->stack_last.p);
 }
 
 
@@ -261,10 +261,10 @@ void luaT_getvarargs (lua_State *L, CallInfo *ci, StkId where, int wanted) {
   if (wanted < 0) {
     wanted = nextra;  /* get all extra arguments available */
     checkstackGCp(L, nextra, where);  /* ensure stack space */
-    L->top = where + nextra;  /* next instruction will need top */
+    L->top.p = where + nextra;  /* next instruction will need top */
   }
   for (i = 0; i < wanted && i < nextra; i++)
-    setobjs2s(L, where + i, ci->func - nextra + i);
+    setobjs2s(L, where + i, ci->func.p - nextra + i);
   for (; i < wanted; i++)   /* complete required results with nil */
     setnilvalue(s2v(where + i));
 }
diff --git a/lundump.c b/lundump.c
index 5aa55c44..aba93f82 100644
--- a/lundump.c
+++ b/lundump.c
@@ -120,10 +120,10 @@ static TString *loadStringN (LoadState *S, Proto *p) {
   }
   else {  /* long string */
     ts = luaS_createlngstrobj(L, size);  /* create string */
-    setsvalue2s(L, L->top, ts);  /* anchor it ('loadVector' can GC) */
+    setsvalue2s(L, L->top.p, ts);  /* anchor it ('loadVector' can GC) */
     luaD_inctop(L);
     loadVector(S, getstr(ts), size);  /* load directly in final place */
-    L->top--;  /* pop string */
+    L->top.p--;  /* pop string */
   }
   luaC_objbarrier(L, p, ts);
   return ts;
@@ -321,7 +321,7 @@ LClosure *luaU_undump(lua_State *L, ZIO *Z, const char *name) {
   S.Z = Z;
   checkHeader(&S);
   cl = luaF_newLclosure(L, loadByte(&S));
-  setclLvalue2s(L, L->top, cl);
+  setclLvalue2s(L, L->top.p, cl);
   luaD_inctop(L);
   cl->p = luaF_newproto(L);
   luaC_objbarrier(L, cl, cl->p);
diff --git a/lvm.c b/lvm.c
index 73a19ba9..2e84dc63 100644
--- a/lvm.c
+++ b/lvm.c
@@ -608,8 +608,8 @@ int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
   if (tm == NULL)  /* no TM? */
     return 0;  /* objects are different */
   else {
-    luaT_callTMres(L, tm, t1, t2, L->top);  /* call TM */
-    return !l_isfalse(s2v(L->top));
+    luaT_callTMres(L, tm, t1, t2, L->top.p);  /* call TM */
+    return !l_isfalse(s2v(L->top.p));
   }
 }
 
@@ -633,13 +633,13 @@ static void copy2buff (StkId top, int n, char *buff) {
 
 /*
 ** Main operation for concatenation: concat 'total' values in the stack,
-** from 'L->top - total' up to 'L->top - 1'.
+** from 'L->top.p - total' up to 'L->top.p - 1'.
 */
 void luaV_concat (lua_State *L, int total) {
   if (total == 1)
     return;  /* "all" values already concatenated */
   do {
-    StkId top = L->top;
+    StkId top = L->top.p;
     int n = 2;  /* number of elements handled in this pass (at least 2) */
     if (!(ttisstring(s2v(top - 2)) || cvt2str(s2v(top - 2))) ||
         !tostring(L, s2v(top - 1)))
@@ -657,7 +657,7 @@ void luaV_concat (lua_State *L, int total) {
       for (n = 1; n < total && tostring(L, s2v(top - n - 1)); n++) {
         size_t l = vslen(s2v(top - n - 1));
         if (l_unlikely(l >= (MAX_SIZE/sizeof(char)) - tl)) {
-          L->top = top - total;  /* pop strings to avoid wasting stack */
+          L->top.p = top - total;  /* pop strings to avoid wasting stack */
           luaG_runerror(L, "string length overflow");
         }
         tl += l;
@@ -674,7 +674,7 @@ void luaV_concat (lua_State *L, int total) {
       setsvalue2s(L, top - n, ts);  /* create result */
     }
     total -= n - 1;  /* got 'n' strings to create one new */
-    L->top -= n - 1;  /* popped 'n' strings and pushed one */
+    L->top.p -= n - 1;  /* popped 'n' strings and pushed one */
   } while (total > 1);  /* repeat until only 1 result left */
 }
 
@@ -808,26 +808,26 @@ static void pushclosure (lua_State *L, Proto *p, UpVal **encup, StkId base,
 */
 void luaV_finishOp (lua_State *L) {
   CallInfo *ci = L->ci;
-  StkId base = ci->func + 1;
+  StkId base = ci->func.p + 1;
   Instruction inst = *(ci->u.l.savedpc - 1);  /* interrupted instruction */
   OpCode op = GET_OPCODE(inst);
   switch (op) {  /* finish its execution */
     case OP_MMBIN: case OP_MMBINI: case OP_MMBINK: {
-      setobjs2s(L, base + GETARG_A(*(ci->u.l.savedpc - 2)), --L->top);
+      setobjs2s(L, base + GETARG_A(*(ci->u.l.savedpc - 2)), --L->top.p);
       break;
     }
     case OP_UNM: case OP_BNOT: case OP_LEN:
     case OP_GETTABUP: case OP_GETTABLE: case OP_GETI:
     case OP_GETFIELD: case OP_SELF: {
-      setobjs2s(L, base + GETARG_A(inst), --L->top);
+      setobjs2s(L, base + GETARG_A(inst), --L->top.p);
       break;
     }
     case OP_LT: case OP_LE:
     case OP_LTI: case OP_LEI:
     case OP_GTI: case OP_GEI:
     case OP_EQ: {  /* note that 'OP_EQI'/'OP_EQK' cannot yield */
-      int res = !l_isfalse(s2v(L->top - 1));
-      L->top--;
+      int res = !l_isfalse(s2v(L->top.p - 1));
+      L->top.p--;
 #if defined(LUA_COMPAT_LT_LE)
       if (ci->callstatus & CIST_LEQ) {  /* "<=" using "<" instead? */
         ci->callstatus ^= CIST_LEQ;  /* clear mark */
@@ -840,11 +840,11 @@ void luaV_finishOp (lua_State *L) {
       break;
     }
     case OP_CONCAT: {
-      StkId top = L->top - 1;  /* top when 'luaT_tryconcatTM' was called */
+      StkId top = L->top.p - 1;  /* top when 'luaT_tryconcatTM' was called */
       int a = GETARG_A(inst);      /* first element to concatenate */
       int total = cast_int(top - 1 - (base + a));  /* yet to concatenate */
       setobjs2s(L, top - 2, top);  /* put TM result in proper position */
-      L->top = top - 1;  /* top is one after last element (at top-2) */
+      L->top.p = top - 1;  /* top is one after last element (at top-2) */
       luaV_concat(L, total);  /* concat them (may yield again) */
       break;
     }
@@ -856,7 +856,7 @@ void luaV_finishOp (lua_State *L) {
       StkId ra = base + GETARG_A(inst);
       /* adjust top to signal correct number of returns, in case the
          return is "up to top" ('isIT') */
-      L->top = ra + ci->u2.nres;
+      L->top.p = ra + ci->u2.nres;
       /* repeat instruction to close other vars. and complete the return */
       ci->u.l.savedpc--;
       break;
@@ -1069,7 +1069,7 @@ void luaV_finishOp (lua_State *L) {
 
 #define updatetrap(ci)  (trap = ci->u.l.trap)
 
-#define updatebase(ci)	(base = ci->func + 1)
+#define updatebase(ci)	(base = ci->func.p + 1)
 
 
 #define updatestack(ci)  \
@@ -1104,7 +1104,7 @@ void luaV_finishOp (lua_State *L) {
 ** Whenever code can raise errors, the global 'pc' and the global
 ** 'top' must be correct to report occasional errors.
 */
-#define savestate(L,ci)		(savepc(L), L->top = ci->top)
+#define savestate(L,ci)		(savepc(L), L->top.p = ci->top.p)
 
 
 /*
@@ -1124,7 +1124,7 @@ void luaV_finishOp (lua_State *L) {
 
 /* 'c' is the limit of live values in the stack */
 #define checkGC(L,c)  \
-	{ luaC_condGC(L, (savepc(L), L->top = (c)), \
+	{ luaC_condGC(L, (savepc(L), L->top.p = (c)), \
                          updatetrap(ci)); \
            luai_threadyield(L); }
 
@@ -1155,7 +1155,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
  startfunc:
   trap = L->hookmask;
  returning:  /* trap already set */
-  cl = clLvalue(s2v(ci->func));
+  cl = clLvalue(s2v(ci->func.p));
   k = cl->p->k;
   pc = ci->u.l.savedpc;
   if (l_unlikely(trap)) {
@@ -1167,7 +1167,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
     }
     ci->u.l.trap = 1;  /* assume trap is on, for now */
   }
-  base = ci->func + 1;
+  base = ci->func.p + 1;
   /* main loop of interpreter */
   for (;;) {
     Instruction i;  /* instruction being executed */
@@ -1176,10 +1176,10 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
       /* low-level line tracing for debugging Lua */
       printf("line: %d\n", luaG_getfuncline(cl->p, pcRel(pc, cl->p)));
     #endif
-    lua_assert(base == ci->func + 1);
-    lua_assert(base <= L->top && L->top <= L->stack_last);
+    lua_assert(base == ci->func.p + 1);
+    lua_assert(base <= L->top.p && L->top.p <= L->stack_last.p);
     /* invalidate top for instructions not expecting it */
-    lua_assert(isIT(i) || (cast_void(L->top = base), 1));
+    lua_assert(isIT(i) || (cast_void(L->top.p = base), 1));
     vmdispatch (GET_OPCODE(i)) {
       vmcase(OP_MOVE) {
         StkId ra = RA(i);
@@ -1238,20 +1238,20 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
       vmcase(OP_GETUPVAL) {
         StkId ra = RA(i);
         int b = GETARG_B(i);
-        setobj2s(L, ra, cl->upvals[b]->v);
+        setobj2s(L, ra, cl->upvals[b]->v.p);
         vmbreak;
       }
       vmcase(OP_SETUPVAL) {
         StkId ra = RA(i);
         UpVal *uv = cl->upvals[GETARG_B(i)];
-        setobj(L, uv->v, s2v(ra));
+        setobj(L, uv->v.p, s2v(ra));
         luaC_barrier(L, uv, s2v(ra));
         vmbreak;
       }
       vmcase(OP_GETTABUP) {
         StkId ra = RA(i);
         const TValue *slot;
-        TValue *upval = cl->upvals[GETARG_B(i)]->v;
+        TValue *upval = cl->upvals[GETARG_B(i)]->v.p;
         TValue *rc = KC(i);
         TString *key = tsvalue(rc);  /* key must be a string */
         if (luaV_fastget(L, upval, key, slot, luaH_getshortstr)) {
@@ -1306,7 +1306,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
       }
       vmcase(OP_SETTABUP) {
         const TValue *slot;
-        TValue *upval = cl->upvals[GETARG_A(i)]->v;
+        TValue *upval = cl->upvals[GETARG_A(i)]->v.p;
         TValue *rb = KB(i);
         TValue *rc = RKC(i);
         TString *key = tsvalue(rb);  /* key must be a string */
@@ -1371,7 +1371,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         if (TESTARG_k(i))  /* non-zero extra argument? */
           c += GETARG_Ax(*pc) * (MAXARG_C + 1);  /* add it to size */
         pc++;  /* skip extra argument */
-        L->top = ra + 1;  /* correct top in case of emergency GC */
+        L->top.p = ra + 1;  /* correct top in case of emergency GC */
         t = luaH_new(L);  /* memory allocation */
         sethvalue2s(L, ra, t);
         if (b != 0 || c != 0)
@@ -1578,9 +1578,9 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
       vmcase(OP_CONCAT) {
         StkId ra = RA(i);
         int n = GETARG_B(i);  /* number of elements to concatenate */
-        L->top = ra + n;  /* mark the end of concat operands */
+        L->top.p = ra + n;  /* mark the end of concat operands */
         ProtectNT(luaV_concat(L, n));
-        checkGC(L, L->top); /* 'luaV_concat' ensures correct top */
+        checkGC(L, L->top.p); /* 'luaV_concat' ensures correct top */
         vmbreak;
       }
       vmcase(OP_CLOSE) {
@@ -1674,7 +1674,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         int b = GETARG_B(i);
         int nresults = GETARG_C(i) - 1;
         if (b != 0)  /* fixed number of arguments? */
-          L->top = ra + b;  /* top signals number of arguments */
+          L->top.p = ra + b;  /* top signals number of arguments */
         /* else previous instruction set top */
         savepc(L);  /* in case of errors */
         if ((newci = luaD_precall(L, ra, nresults)) == NULL)
@@ -1693,19 +1693,19 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         /* delta is virtual 'func' - real 'func' (vararg functions) */
         int delta = (nparams1) ? ci->u.l.nextraargs + nparams1 : 0;
         if (b != 0)
-          L->top = ra + b;
+          L->top.p = ra + b;
         else  /* previous instruction set top */
-          b = cast_int(L->top - ra);
+          b = cast_int(L->top.p - ra);
         savepc(ci);  /* several calls here can raise errors */
         if (TESTARG_k(i)) {
           luaF_closeupval(L, base);  /* close upvalues from current call */
-          lua_assert(L->tbclist < base);  /* no pending tbc variables */
-          lua_assert(base == ci->func + 1);
+          lua_assert(L->tbclist.p < base);  /* no pending tbc variables */
+          lua_assert(base == ci->func.p + 1);
         }
         if ((n = luaD_pretailcall(L, ci, ra, b, delta)) < 0)  /* Lua function? */
           goto startfunc;  /* execute the callee */
         else {  /* C function? */
-          ci->func -= delta;  /* restore 'func' (if vararg) */
+          ci->func.p -= delta;  /* restore 'func' (if vararg) */
           luaD_poscall(L, ci, n);  /* finish caller */
           updatetrap(ci);  /* 'luaD_poscall' can change hooks */
           goto ret;  /* caller returns after the tail call */
@@ -1716,19 +1716,19 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         int n = GETARG_B(i) - 1;  /* number of results */
         int nparams1 = GETARG_C(i);
         if (n < 0)  /* not fixed? */
-          n = cast_int(L->top - ra);  /* get what is available */
+          n = cast_int(L->top.p - ra);  /* get what is available */
         savepc(ci);
         if (TESTARG_k(i)) {  /* may there be open upvalues? */
           ci->u2.nres = n;  /* save number of returns */
-          if (L->top < ci->top)
-            L->top = ci->top;
+          if (L->top.p < ci->top.p)
+            L->top.p = ci->top.p;
           luaF_close(L, base, CLOSEKTOP, 1);
           updatetrap(ci);
           updatestack(ci);
         }
         if (nparams1)  /* vararg function? */
-          ci->func -= ci->u.l.nextraargs + nparams1;
-        L->top = ra + n;  /* set call for 'luaD_poscall' */
+          ci->func.p -= ci->u.l.nextraargs + nparams1;
+        L->top.p = ra + n;  /* set call for 'luaD_poscall' */
         luaD_poscall(L, ci, n);
         updatetrap(ci);  /* 'luaD_poscall' can change hooks */
         goto ret;
@@ -1736,7 +1736,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
       vmcase(OP_RETURN0) {
         if (l_unlikely(L->hookmask)) {
           StkId ra = RA(i);
-          L->top = ra;
+          L->top.p = ra;
           savepc(ci);
           luaD_poscall(L, ci, 0);  /* no hurry... */
           trap = 1;
@@ -1744,16 +1744,16 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         else {  /* do the 'poscall' here */
           int nres;
           L->ci = ci->previous;  /* back to caller */
-          L->top = base - 1;
+          L->top.p = base - 1;
           for (nres = ci->nresults; l_unlikely(nres > 0); nres--)
-            setnilvalue(s2v(L->top++));  /* all results are nil */
+            setnilvalue(s2v(L->top.p++));  /* all results are nil */
         }
         goto ret;
       }
       vmcase(OP_RETURN1) {
         if (l_unlikely(L->hookmask)) {
           StkId ra = RA(i);
-          L->top = ra + 1;
+          L->top.p = ra + 1;
           savepc(ci);
           luaD_poscall(L, ci, 1);  /* no hurry... */
           trap = 1;
@@ -1762,13 +1762,13 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
           int nres = ci->nresults;
           L->ci = ci->previous;  /* back to caller */
           if (nres == 0)
-            L->top = base - 1;  /* asked for no results */
+            L->top.p = base - 1;  /* asked for no results */
           else {
             StkId ra = RA(i);
             setobjs2s(L, base - 1, ra);  /* at least this result */
-            L->top = base;
+            L->top.p = base;
             for (; l_unlikely(nres > 1); nres--)
-              setnilvalue(s2v(L->top++));  /* complete missing results */
+              setnilvalue(s2v(L->top.p++));  /* complete missing results */
           }
         }
        ret:  /* return from a Lua function */
@@ -1824,7 +1824,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         */
         /* push function, state, and control variable */
         memcpy(ra + 4, ra, 3 * sizeof(*ra));
-        L->top = ra + 4 + 3;
+        L->top.p = ra + 4 + 3;
         ProtectNT(luaD_call(L, ra + 4, GETARG_C(i)));  /* do the call */
         updatestack(ci);  /* stack may have changed */
         i = *(pc++);  /* go to next instruction */
@@ -1846,9 +1846,9 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         unsigned int last = GETARG_C(i);
         Table *h = hvalue(s2v(ra));
         if (n == 0)
-          n = cast_int(L->top - ra) - 1;  /* get up to the top */
+          n = cast_int(L->top.p - ra) - 1;  /* get up to the top */
         else
-          L->top = ci->top;  /* correct top in case of emergency GC */
+          L->top.p = ci->top.p;  /* correct top in case of emergency GC */
         last += n;
         if (TESTARG_k(i)) {
           last += GETARG_Ax(*pc) * (MAXARG_C + 1);