Add shared, use age bits

src/lapi.c

@@ -904,6 +904,8 @@ LUA_API int lua_setmetatable (lua_State *L, int objindex) {
   }
   switch (ttype(obj)) {
     case LUA_TTABLE: {
+      if (isshared(hvalue(obj)))
+        luaG_runerror(L, "can't setmetatable to shared table");
       hvalue(obj)->metatable = mt;
       if (mt) {
         luaC_objbarrier(L, gcvalue(obj), mt);

src/lgc.c

@@ -192,7 +192,7 @@ static int iscleared (global_State *g, const GCObject *o) {
 */
 void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
   global_State *g = G(L);
-  lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
+  lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o) && !isshared(o));
   if (keepinvariant(g)) {  /* must keep invariant? */
     reallymarkobject(g, v);  /* restore invariant */
     if (isold(o)) {
@@ -213,7 +213,7 @@ void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
 */
 void luaC_barrierback_ (lua_State *L, GCObject *o) {
   global_State *g = G(L);
-  lua_assert(isblack(o) && !isdead(g, o));
+  lua_assert(isblack(o) && !isdead(g, o) && !isshared(o));
   lua_assert(g->gckind != KGC_GEN || (isold(o) && getage(o) != G_TOUCHED1));
   if (getage(o) != G_TOUCHED2)  /* not already in gray list? */
     linkobjgclist(o, g->grayagain);  /* link it in 'grayagain' */
@@ -226,7 +226,8 @@ void luaC_fix (lua_State *L, GCObject *o) {
   global_State *g = G(L);
   lua_assert(g->allgc == o);  /* object must be 1st in 'allgc' list! */
   white2gray(o);  /* they will be gray forever */
-  setage(o, G_OLD);  /* and old forever */
+  if (!isshared(o))
+    setage(o, G_OLD);  /* and old forever */
   g->allgc = o->next;  /* remove object from 'allgc' list */
   o->next = g->fixedgc;  /* link it to 'fixedgc' list */
   g->fixedgc = o;
@@ -266,6 +267,8 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
 ** to avoid barriers, as their values will be revisited by the thread.)
 */
 static void reallymarkobject (global_State *g, GCObject *o) {
+  if (isshared(o))
+    return;
   white2gray(o);
   switch (o->tt) {
     case LUA_VSHRSTR:
@@ -976,7 +979,9 @@ static void setpause (global_State *g);
 static void sweep2old (lua_State *L, GCObject **p) {
   GCObject *curr;
   while ((curr = *p) != NULL) {
-    if (iswhite(curr)) {  /* is 'curr' dead? */
+    if (isshared(curr))
+       p = &curr->next;  /* go to next element */
+    else if (iswhite(curr)) {  /* is 'curr' dead? */
       lua_assert(isdead(G(L), curr));
       *p = curr->next;  /* remove 'curr' from list */
       freeobj(L, curr);  /* erase 'curr' */
@@ -1010,7 +1015,9 @@ static GCObject **sweepgen (lua_State *L, global_State *g, GCObject **p,
   int white = luaC_white(g);
   GCObject *curr;
   while ((curr = *p) != limit) {
-    if (iswhite(curr)) {  /* is 'curr' dead? */
+    if (isshared(curr))
+      p = &curr->next;  /* go to next element */
+    else if (iswhite(curr)) {  /* is 'curr' dead? */
       lua_assert(!isold(curr) && isdead(g, curr));
       *p = curr->next;  /* remove 'curr' from list */
       freeobj(L, curr);  /* erase 'curr' */

src/lgc.h

@@ -107,13 +107,17 @@
 #define G_OLD		4	/* really old object (not to be visited) */
 #define G_TOUCHED1	5	/* old object touched this cycle */
 #define G_TOUCHED2	6	/* old object touched in previous cycle */
+#define G_SHARED	7	/* object is shared */
 
 #define AGEBITS		7  /* all age bits (111) */
 
 #define getage(o)	((o)->marked & AGEBITS)
 #define setage(o,a)  ((o)->marked = cast_byte(((o)->marked & (~AGEBITS)) | a))
 #define isold(o)	(getage(o) > G_SURVIVAL)
 
+#define isshared(x)     (getage(x) == G_SHARED)
+#define makeshared(x)   setage(x, G_SHARED)
+
 #define changeage(o,f,t)  \
 	check_exp(getage(o) == (f), (o)->marked ^= ((f)^(t)))
 
@@ -160,15 +164,15 @@
 
 
 #define luaC_barrier(L,p,v) (  \
-	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v))) ?  \
+	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v)) && !isshared(gcvalue(v))) ?  \
 	luaC_barrier_(L,obj2gco(p),gcvalue(v)) : cast_void(0))
 
 #define luaC_barrierback(L,p,v) (  \
-	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v))) ? \
+	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v)) && !isshared(gcvalue(v))) ? \
 	luaC_barrierback_(L,p) : cast_void(0))
 
 #define luaC_objbarrier(L,p,o) (  \
-	(isblack(p) && iswhite(o)) ? \
+	(isblack(p) && iswhite(o) && !isshared(o)) ? \
 	luaC_barrier_(L,obj2gco(p),obj2gco(o)) : cast_void(0))
 
 LUAI_FUNC void luaC_fix (lua_State *L, GCObject *o);

src/lobject.h

@@ -100,7 +100,7 @@ typedef struct TValue {
 */
 #define checkliveness(L,obj) \
 	((void)L, lua_longassert(!iscollectable(obj) || \
-		(righttt(obj) && (L == NULL || !isdead(G(L),gcvalue(obj))))))
+		(righttt(obj) && (L == NULL || !isdead(G(L),gcvalue(obj)) || isshared(gcvalue(obj))))))
 
 
 /* Macros to set values */

src/ltable.c

@@ -760,7 +760,10 @@ const TValue *luaH_get (Table *t, const TValue *key) {
 ** barrier and invalidate the TM cache.
 */
 TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
-  const TValue *p = luaH_get(t, key);
+  const TValue *p;
+  if(isshared(t))
+    luaG_runerror(L,"attempt to change a shared table");
+  p = luaH_get(t, key);
   if (!isabstkey(p))
     return cast(TValue *, p);
   else return luaH_newkey(L, t, key);

src/lvm.c

@@ -334,6 +334,8 @@ void luaV_finishset (lua_State *L, const TValue *t, TValue *key,
     const TValue *tm;  /* '__newindex' metamethod */
     if (slot != NULL) {  /* is 't' a table? */
       Table *h = hvalue(t);  /* save 't' table */
+      if (isshared(h))
+        luaG_typeerror(L, t, "change");
       lua_assert(isempty(slot));  /* slot must be empty */
       tm = fasttm(L, h->metatable, TM_NEWINDEX);  /* get metamethod */
       if (tm == NULL) {  /* no metamethod? */
@@ -358,7 +360,7 @@ void luaV_finishset (lua_State *L, const TValue *t, TValue *key,
       return;
     }
     t = tm;  /* else repeat assignment over 'tm' */
-    if (luaV_fastget(L, t, key, slot, luaH_get)) {
+    if (luaV_fastset(L, t, key, slot, luaH_get)) {
       luaV_finishfastset(L, t, slot, val);
       return;  /* done */
     }
@@ -1270,7 +1272,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         TValue *rb = KB(i);
         TValue *rc = RKC(i);
         TString *key = tsvalue(rb);  /* key must be a string */
-        if (luaV_fastget(L, upval, key, slot, luaH_getshortstr)) {
+        if (luaV_fastset(L, upval, key, slot, luaH_getshortstr)) {
           luaV_finishfastset(L, upval, slot, rc);
         }
         else
@@ -1283,8 +1285,8 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         TValue *rc = RKC(i);  /* value */
         lua_Unsigned n;
         if (ttisinteger(rb)  /* fast track for integers? */
-            ? (cast_void(n = ivalue(rb)), luaV_fastgeti(L, s2v(ra), n, slot))
-            : luaV_fastget(L, s2v(ra), rb, slot, luaH_get)) {
+            ? (cast_void(n = ivalue(rb)), luaV_fastseti(L, s2v(ra), n, slot))
+            : luaV_fastset(L, s2v(ra), rb, slot, luaH_get)) {
           luaV_finishfastset(L, s2v(ra), slot, rc);
         }
         else
@@ -1295,7 +1297,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         const TValue *slot;
         int c = GETARG_B(i);
         TValue *rc = RKC(i);
-        if (luaV_fastgeti(L, s2v(ra), c, slot)) {
+        if (luaV_fastseti(L, s2v(ra), c, slot)) {
           luaV_finishfastset(L, s2v(ra), slot, rc);
         }
         else {
@@ -1310,7 +1312,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         TValue *rb = KB(i);
         TValue *rc = RKC(i);
         TString *key = tsvalue(rb);  /* key must be a string */
-        if (luaV_fastget(L, s2v(ra), key, slot, luaH_getshortstr)) {
+        if (luaV_fastset(L, s2v(ra), key, slot, luaH_getshortstr)) {
           luaV_finishfastset(L, s2v(ra), slot, rc);
         }
         else

src/lvm.h

@@ -86,6 +86,7 @@ typedef enum {
    : (slot = f(hvalue(t), k),  /* else, do raw access */  \
       !isempty(slot)))  /* result not empty? */
 
+#define luaV_fastset(L,t,k,slot,f) (luaV_fastget(L,t,k,slot,f)) && !isshared(hvalue(t))
 
 /*
 ** Special case of 'luaV_fastget' for integers, inlining the fast case
@@ -98,6 +99,7 @@ typedef enum {
               ? &hvalue(t)->array[k - 1] : luaH_getint(hvalue(t), k), \
       !isempty(slot)))  /* result not empty? */
 
+#define luaV_fastseti(L,t,k,slot) (luaV_fastgeti(L,t,k,slot)) && !isshared(hvalue(t))
 
 /*
 ** Finish a fast set operation (when fast get succeeds). In that case,