diff --git a/3rd/lua/lapi.c b/3rd/lua/lapi.c
index f91769be..6a28c54f 100644
--- a/3rd/lua/lapi.c
+++ b/3rd/lua/lapi.c
@@ -1180,18 +1180,19 @@ LUA_API int lua_status (lua_State *L) {
 LUA_API int lua_gc (lua_State *L, int what, ...) {
   va_list argp;
   int res = 0;
-  global_State *g;
+  global_State *g = G(L);
+  if (g->gcstp & GCSTPGC)  /* internal stop? */
+    return -1;  /* all options are invalid when stopped */
   lua_lock(L);
-  g = G(L);
   va_start(argp, what);
   switch (what) {
     case LUA_GCSTOP: {
-      g->gcrunning = 0;
+      g->gcstp = GCSTPUSR;  /* stopped by the user */
       break;
     }
     case LUA_GCRESTART: {
       luaE_setdebt(g, 0);
-      g->gcrunning = 1;
+      g->gcstp = 0;  /* (GCSTPGC must be already zero here) */
       break;
     }
     case LUA_GCCOLLECT: {
@@ -1210,8 +1211,8 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
     case LUA_GCSTEP: {
       int data = va_arg(argp, int);
       l_mem debt = 1;  /* =1 to signal that it did an actual step */
-      lu_byte oldrunning = g->gcrunning;
-      g->gcrunning = 1;  /* allow GC to run */
+      lu_byte oldstp = g->gcstp;
+      g->gcstp = 0;  /* allow GC to run (GCSTPGC must be zero here) */
       if (data == 0) {
         luaE_setdebt(g, 0);  /* do a basic step */
         luaC_step(L);
@@ -1221,7 +1222,7 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
         luaE_setdebt(g, debt);
         luaC_checkGC(L);
       }
-      g->gcrunning = oldrunning;  /* restore previous state */
+      g->gcstp = oldstp;  /* restore previous state */
       if (debt > 0 && g->gcstate == GCSpause)  /* end of cycle? */
         res = 1;  /* signal it */
       break;
@@ -1239,7 +1240,7 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
       break;
     }
     case LUA_GCISRUNNING: {
-      res = g->gcrunning;
+      res = gcrunning(g);
       break;
     }
     case LUA_GCGEN: {
diff --git a/3rd/lua/lbaselib.c b/3rd/lua/lbaselib.c
index 912c4cc6..1d60c9de 100644
--- a/3rd/lua/lbaselib.c
+++ b/3rd/lua/lbaselib.c
@@ -182,12 +182,20 @@ static int luaB_rawset (lua_State *L) {
 
 
 static int pushmode (lua_State *L, int oldmode) {
-  lua_pushstring(L, (oldmode == LUA_GCINC) ? "incremental"
-                                           : "generational");
+  if (oldmode == -1)
+    luaL_pushfail(L);  /* invalid call to 'lua_gc' */
+  else
+    lua_pushstring(L, (oldmode == LUA_GCINC) ? "incremental"
+                                             : "generational");
   return 1;
 }
 
 
+/*
+** check whether call to 'lua_gc' was valid (not inside a finalizer)
+*/
+#define checkvalres(res) { if (res == -1) break; }
+
 static int luaB_collectgarbage (lua_State *L) {
   static const char *const opts[] = {"stop", "restart", "collect",
     "count", "step", "setpause", "setstepmul",
@@ -200,12 +208,14 @@ static int luaB_collectgarbage (lua_State *L) {
     case LUA_GCCOUNT: {
       int k = lua_gc(L, o);
       int b = lua_gc(L, LUA_GCCOUNTB);
+      checkvalres(k);
       lua_pushnumber(L, (lua_Number)k + ((lua_Number)b/1024));
       return 1;
     }
     case LUA_GCSTEP: {
       int step = (int)luaL_optinteger(L, 2, 0);
       int res = lua_gc(L, o, step);
+      checkvalres(res);
       lua_pushboolean(L, res);
       return 1;
     }
@@ -213,11 +223,13 @@ static int luaB_collectgarbage (lua_State *L) {
     case LUA_GCSETSTEPMUL: {
       int p = (int)luaL_optinteger(L, 2, 0);
       int previous = lua_gc(L, o, p);
+      checkvalres(previous);
       lua_pushinteger(L, previous);
       return 1;
     }
     case LUA_GCISRUNNING: {
       int res = lua_gc(L, o);
+      checkvalres(res);
       lua_pushboolean(L, res);
       return 1;
     }
@@ -234,10 +246,13 @@ static int luaB_collectgarbage (lua_State *L) {
     }
     default: {
       int res = lua_gc(L, o);
+      checkvalres(res);
       lua_pushinteger(L, res);
       return 1;
     }
   }
+  luaL_pushfail(L);  /* invalid call (inside a finalizer) */
+  return 1;
 }
 
 
diff --git a/3rd/lua/ldebug.c b/3rd/lua/ldebug.c
index 30a28828..a716d95e 100644
--- a/3rd/lua/ldebug.c
+++ b/3rd/lua/ldebug.c
@@ -34,8 +34,8 @@
 #define noLuaClosure(f)		((f) == NULL || (f)->c.tt == LUA_VCCL)
 
 
-static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
-                                    const char **name);
+static const char *funcnamefromcall (lua_State *L, CallInfo *ci,
+                                                   const char **name);
 
 
 static int currentpc (CallInfo *ci) {
@@ -304,7 +304,7 @@ static void collectvalidlines (lua_State *L, Closure *f) {
     if (!p->is_vararg)  /* regular function? */
       i = 0;  /* consider all instructions */
     else {  /* vararg function */
-      lua_assert(p->code[0] == OP_VARARGPREP);
+      lua_assert(GET_OPCODE(p->code[0]) == OP_VARARGPREP);
       currentline = nextline(p, currentline, 0);
       i = 1;  /* skip first instruction (OP_VARARGPREP) */
     }
@@ -317,15 +317,9 @@ static void collectvalidlines (lua_State *L, Closure *f) {
 
 
 static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
-  if (ci == NULL)  /* no 'ci'? */
-    return NULL;  /* no info */
-  else if (ci->callstatus & CIST_FIN) {  /* is this a finalizer? */
-    *name = "__gc";
-    return "metamethod";  /* report it as such */
-  }
-  /* calling function is a known Lua function? */
-  else if (!(ci->callstatus & CIST_TAIL) && isLua(ci->previous))
-    return funcnamefromcode(L, ci->previous, name);
+  /* calling function is a known function? */
+  if (ci != NULL && !(ci->callstatus & CIST_TAIL))
+    return funcnamefromcall(L, ci->previous, name);
   else return NULL;  /* no way to find a name */
 }
 
@@ -597,16 +591,10 @@ static const char *getobjname (const Proto *p, int lastpc, int reg,
 ** Returns what the name is (e.g., "for iterator", "method",
 ** "metamethod") and sets '*name' to point to the name.
 */
-static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
-                                     const char **name) {
+static const char *funcnamefromcode (lua_State *L, const Proto *p,
+                                     int pc, const char **name) {
   TMS tm = (TMS)0;  /* (initial value avoids warnings) */
-  const Proto *p = ci_func(ci)->p;  /* calling function */
-  int pc = currentpc(ci);  /* calling instruction index */
   Instruction i = p->code[pc];  /* calling instruction */
-  if (ci->callstatus & CIST_HOOKED) {  /* was it called inside a hook? */
-    *name = "?";
-    return "hook";
-  }
   switch (GET_OPCODE(i)) {
     case OP_CALL:
     case OP_TAILCALL:
@@ -643,6 +631,26 @@ static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
   return "metamethod";
 }
 
+
+/*
+** Try to find a name for a function based on how it was called.
+*/
+static const char *funcnamefromcall (lua_State *L, CallInfo *ci,
+                                                   const char **name) {
+  if (ci->callstatus & CIST_HOOKED) {  /* was it called inside a hook? */
+    *name = "?";
+    return "hook";
+  }
+  else if (ci->callstatus & CIST_FIN) {  /* was it called as a finalizer? */
+    *name = "__gc";
+    return "metamethod";  /* report it as such */
+  }
+  else if (isLua(ci))
+    return funcnamefromcode(L, ci_func(ci)->p, currentpc(ci), name);
+  else
+    return NULL;
+}
+
 /* }====================================================== */
 
 
@@ -728,14 +736,14 @@ l_noret luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
 
 
 /*
-** Raise an error for calling a non-callable object. Try to find
-** a name for the object based on the code that made the call
-** ('funcnamefromcode'); if it cannot get a name there, try 'varinfo'.
+** Raise an error for calling a non-callable object. Try to find a name
+** for the object based on how it was called ('funcnamefromcall'); if it
+** cannot get a name there, try 'varinfo'.
 */
 l_noret luaG_callerror (lua_State *L, const TValue *o) {
   CallInfo *ci = L->ci;
   const char *name = NULL;  /* to avoid warnings */
-  const char *kind = (isLua(ci)) ? funcnamefromcode(L, ci, &name) : NULL;
+  const char *kind = funcnamefromcall(L, ci, &name);
   const char *extra = kind ? formatvarinfo(L, kind, name) : varinfo(L, o);
   typeerror(L, o, "call", extra);
 }
diff --git a/3rd/lua/ldo.c b/3rd/lua/ldo.c
index f282a773..a48e35f9 100644
--- a/3rd/lua/ldo.c
+++ b/3rd/lua/ldo.c
@@ -530,10 +530,10 @@ int luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func,
       int fsize = p->maxstacksize;  /* frame size */
       int nfixparams = p->numparams;
       int i;
+      checkstackGCp(L, fsize - delta, func);
       ci->func -= delta;  /* restore 'func' (if vararg) */
       for (i = 0; i < narg1; i++)  /* move down function and arguments */
         setobjs2s(L, ci->func + i, func + i);
-      checkstackGC(L, fsize);
       func = ci->func;  /* moved-down function */
       for (; narg1 <= nfixparams; narg1++)
         setnilvalue(s2v(func + narg1));  /* complete missing arguments */
diff --git a/3rd/lua/lgc.c b/3rd/lua/lgc.c
index e90766dc..3d509b14 100644
--- a/3rd/lua/lgc.c
+++ b/3rd/lua/lgc.c
@@ -908,18 +908,18 @@ static void GCTM (lua_State *L) {
   if (!notm(tm)) {  /* is there a finalizer? */
     int status;
     lu_byte oldah = L->allowhook;
-    int running  = g->gcrunning;
+    int oldgcstp  = g->gcstp;
+    g->gcstp = GCSTPGC;  /* avoid GC steps */
     L->allowhook = 0;  /* stop debug hooks during GC metamethod */
-    g->gcrunning = 0;  /* avoid GC steps */
     setobj2s(L, L->top++, tm);  /* push finalizer... */
     setobj2s(L, L->top++, &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);
     L->ci->callstatus &= ~CIST_FIN;  /* not running a finalizer anymore */
     L->allowhook = oldah;  /* restore hooks */
-    g->gcrunning = running;  /* restore state */
+    g->gcstp = oldgcstp;  /* restore state */
     if (l_unlikely(status != LUA_OK)) {  /* error while running __gc? */
-      luaE_warnerror(L, "__gc metamethod");
+      luaE_warnerror(L, "__gc");
       L->top--;  /* pops error object */
     }
   }
@@ -1508,9 +1508,11 @@ static void deletelist (lua_State *L, GCObject *p, GCObject *limit) {
 */
 void luaC_freeallobjects (lua_State *L) {
   global_State *g = G(L);
+  g->gcstp = GCSTPGC;
   luaC_changemode(L, KGC_INC);
   separatetobefnz(g, 1);  /* separate all objects with finalizers */
   lua_assert(g->finobj == NULL);
+  g->gcstp = 0;
   callallpendingfinalizers(L);
   deletelist(L, g->allgc, obj2gco(g->mainthread));
   deletelist(L, g->finobj, NULL);
@@ -1653,6 +1655,7 @@ void luaC_runtilstate (lua_State *L, int statesmask) {
 }
 
 
+
 /*
 ** Performs a basic incremental step. The debt and step size are
 ** converted from bytes to "units of work"; then the function loops
@@ -1684,7 +1687,7 @@ static void incstep (lua_State *L, global_State *g) {
 void luaC_step (lua_State *L) {
   global_State *g = G(L);
   lua_assert(!g->gcemergency);
-  if (g->gcrunning) {  /* running? */
+  if (gcrunning(g)) {  /* running? */
     if(isdecGCmodegen(g))
       genstep(L, g);
     else
diff --git a/3rd/lua/lgc.h b/3rd/lua/lgc.h
index 62a44e1a..cd77ddf1 100644
--- a/3rd/lua/lgc.h
+++ b/3rd/lua/lgc.h
@@ -153,6 +153,15 @@
 */
 #define isdecGCmodegen(g)	(g->gckind == KGC_GEN || g->lastatomic != 0)
 
+
+/*
+** Control when GC is running:
+*/
+#define GCSTPUSR	1  /* bit true when GC stopped by user */
+#define GCSTPGC		2  /* bit true when GC stopped by itself */
+#define gcrunning(g)	((g)->gcstp == 0)
+
+
 /*
 ** Does one step of collection when debt becomes positive. 'pre'/'pos'
 ** allows some adjustments to be done only when needed. macro
diff --git a/3rd/lua/llimits.h b/3rd/lua/llimits.h
index 6c56ba5a..52a32f92 100644
--- a/3rd/lua/llimits.h
+++ b/3rd/lua/llimits.h
@@ -361,7 +361,7 @@ typedef l_uint32 Instruction;
 #define condchangemem(L,pre,pos)	((void)0)
 #else
 #define condchangemem(L,pre,pos)  \
-	{ if (G(L)->gcrunning) { pre; luaC_fullgc(L, 0); pos; } }
+	{ if (gcrunning(G(L))) { pre; luaC_fullgc(L, 0); pos; } }
 #endif
 
 #endif
diff --git a/3rd/lua/lstate.c b/3rd/lua/lstate.c
index 846162a5..365bcdd6 100644
--- a/3rd/lua/lstate.c
+++ b/3rd/lua/lstate.c
@@ -236,7 +236,7 @@ static void f_luaopen (lua_State *L, void *ud) {
   luaS_init(L);
   luaT_init(L);
   luaX_init(L);
-  g->gcrunning = 1;  /* allow gc */
+  g->gcstp = 0;  /* allow gc */
   setnilvalue(&g->nilvalue);  /* now state is complete */
   luai_userstateopen(L);
 }
@@ -271,6 +271,7 @@ static void close_state (lua_State *L) {
   if (!completestate(g))  /* closing a partially built state? */
     luaC_freeallobjects(L);  /* just collect its objects */
   else {  /* closing a fully built state */
+    L->ci = &L->base_ci;  /* unwind CallInfo list */
     luaD_closeprotected(L, 1, LUA_OK);  /* close all upvalues */
     luaC_freeallobjects(L);  /* collect all objects */
     luai_userstateclose(L);
@@ -371,7 +372,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   g->warnf = NULL;
   g->ud_warn = NULL;
   g->mainthread = L;
-  g->gcrunning = 0;  /* no GC while building state */
+  g->gcstp = GCSTPGC;  /* no GC while building state */
   g->strt.size = g->strt.nuse = 0;
   g->strt.hash = NULL;
   setnilvalue(&g->l_registry);
diff --git a/3rd/lua/lstate.h b/3rd/lua/lstate.h
index 9f0e41cb..b18568e9 100644
--- a/3rd/lua/lstate.h
+++ b/3rd/lua/lstate.h
@@ -209,7 +209,7 @@ typedef struct CallInfo {
 #define CIST_YPCALL	(1<<4)	/* doing a yieldable protected call */
 #define CIST_TAIL	(1<<5)	/* call was tail called */
 #define CIST_HOOKYIELD	(1<<6)	/* last hook called yielded */
-#define CIST_FIN	(1<<7)	/* call is running a finalizer */
+#define CIST_FIN	(1<<7)	/* function "called" a finalizer */
 #define CIST_TRAN	(1<<8)	/* 'ci' has transfer information */
 #define CIST_CLSRET	(1<<9)  /* function is closing tbc variables */
 /* Bits 10-12 are used for CIST_RECST (see below) */
@@ -262,7 +262,7 @@ typedef struct global_State {
   lu_byte gcstopem;  /* stops emergency collections */
   lu_byte genminormul;  /* control for minor generational collections */
   lu_byte genmajormul;  /* control for major generational collections */
-  lu_byte gcrunning;  /* true if GC is running */
+  lu_byte gcstp;  /* control whether GC is running */
   lu_byte gcemergency;  /* true if this is an emergency collection */
   lu_byte gcpause;  /* size of pause between successive GCs */
   lu_byte gcstepmul;  /* GC "speed" */
diff --git a/3rd/lua/ltable.c b/3rd/lua/ltable.c
index 95cae18e..045155ea 100644
--- a/3rd/lua/ltable.c
+++ b/3rd/lua/ltable.c
@@ -146,26 +146,24 @@ static int l_hashfloat (lua_Number n) {
 
 /*
 ** returns the 'main' position of an element in a table (that is,
-** the index of its hash value). The key comes broken (tag in 'ktt'
-** and value in 'vkl') so that we can call it on keys inserted into
-** nodes.
+** the index of its hash value).
 */
-static Node *mainposition (const Table *t, int ktt, const Value kvl) {
-  switch (withvariant(ktt)) {
+static Node *mainpositionTV (const Table *t, const TValue *key) {
+  switch (ttypetag(key)) {
     case LUA_VNUMINT: {
-      lua_Integer key = ivalueraw(kvl);
-      return hashint(t, key);
+      lua_Integer i = ivalue(key);
+      return hashint(t, i);
     }
     case LUA_VNUMFLT: {
-      lua_Number n = fltvalueraw(kvl);
+      lua_Number n = fltvalue(key);
       return hashmod(t, l_hashfloat(n));
     }
     case LUA_VSHRSTR: {
-      TString *ts = tsvalueraw(kvl);
+      TString *ts = tsvalue(key);
       return hashstr(t, ts);
     }
     case LUA_VLNGSTR: {
-      TString *ts = tsvalueraw(kvl);
+      TString *ts = tsvalue(key);
       return hashpow2(t, luaS_hashlongstr(ts));
     }
     case LUA_VFALSE:
@@ -173,26 +171,25 @@ static Node *mainposition (const Table *t, int ktt, const Value kvl) {
     case LUA_VTRUE:
       return hashboolean(t, 1);
     case LUA_VLIGHTUSERDATA: {
-      void *p = pvalueraw(kvl);
+      void *p = pvalue(key);
       return hashpointer(t, p);
     }
     case LUA_VLCF: {
-      lua_CFunction f = fvalueraw(kvl);
+      lua_CFunction f = fvalue(key);
       return hashpointer(t, f);
     }
     default: {
-      GCObject *o = gcvalueraw(kvl);
+      GCObject *o = gcvalue(key);
       return hashpointer(t, o);
     }
   }
 }
 
 
-/*
-** Returns the main position of an element given as a 'TValue'
-*/
-static Node *mainpositionTV (const Table *t, const TValue *key) {
-  return mainposition(t, rawtt(key), valraw(key));
+l_sinline Node *mainpositionfromnode (const Table *t, Node *nd) {
+  TValue key;
+  getnodekey(cast(lua_State *, NULL), &key, nd);
+  return mainpositionTV(t, &key);
 }
 
 
@@ -695,7 +692,7 @@ void luaH_newkey (lua_State *L, Table *t, const TValue *key, TValue *value) {
       return;
     }
     lua_assert(!isdummy(t));
-    othern = mainposition(t, keytt(mp), keyval(mp));
+    othern = mainpositionfromnode(t, mp);
     if (othern != mp) {  /* is colliding node out of its main position? */
       /* yes; move colliding node into free position */
       while (othern + gnext(othern) != mp)  /* find previous */