diff --git a/ghc/includes/Stable.h b/ghc/includes/Stable.h
index 4552439e8779fe7dfa0d6f5bb8fc420450ff9ed0..70c467429046b45e306eb2bc870d65f2d2a49cce 100644
--- a/ghc/includes/Stable.h
+++ b/ghc/includes/Stable.h
@@ -1,5 +1,5 @@
/* -----------------------------------------------------------------------------
- * $Id: Stable.h,v 1.2 1999/02/05 16:02:28 simonm Exp $
+ * $Id: Stable.h,v 1.3 1999/02/26 12:46:45 simonm Exp $
*
* (c) The GHC Team, 1998-1999
*
@@ -22,9 +22,9 @@ extern StgStablePtr splitStablePtr(StgStablePtr sp);
extern StgStablePtr getStablePtr(StgPtr p);
typedef struct {
- StgPtr addr; /* either Haskell object or free list */
+ StgPtr addr; /* Haskell object, free list, or NULL */
StgWord weight; /* used for reference counting */
- unsigned int keep; /* set by the garbage collector */
+ StgClosure *sn_obj; /* the StableName object (or NULL) */
} snEntry;
extern snEntry *stable_ptr_table;
diff --git a/ghc/rts/GC.c b/ghc/rts/GC.c
index fad50be014f10ccfd16852ed62c63b3bfeb5b021..d823c44d1eaeb1e416fda4869981a53ef46e4535 100644
--- a/ghc/rts/GC.c
+++ b/ghc/rts/GC.c
@@ -1,5 +1,5 @@
/* -----------------------------------------------------------------------------
- * $Id: GC.c,v 1.42 1999/02/25 17:52:33 simonm Exp $
+ * $Id: GC.c,v 1.43 1999/02/26 12:46:46 simonm Exp $
*
* (c) The GHC Team 1998-1999
*
@@ -1099,10 +1099,6 @@ loop:
recordMutable((StgMutClosure *)to);
return to;
- case STABLE_NAME:
- stable_ptr_table[((StgStableName *)q)->sn].keep = rtsTrue;
- return copy(q,sizeofW(StgStableName),step);
-
case FUN_1_0:
case FUN_0_1:
case CONSTR_1_0:
@@ -1140,6 +1136,7 @@ loop:
case CAF_ENTERED:
case WEAK:
case FOREIGN:
+ case STABLE_NAME:
return copy(q,sizeW_fromITBL(info),step);
case CAF_BLACKHOLE:
diff --git a/ghc/rts/PrimOps.hc b/ghc/rts/PrimOps.hc
index f711d9bb74682291fb9076c99c69b5f5b7ef5b05..33e2d2332d750d2a8585669790f28d27ef216d2c 100644
--- a/ghc/rts/PrimOps.hc
+++ b/ghc/rts/PrimOps.hc
@@ -1,5 +1,5 @@
/* -----------------------------------------------------------------------------
- * $Id: PrimOps.hc,v 1.16 1999/02/17 15:57:39 simonm Exp $
+ * $Id: PrimOps.hc,v 1.17 1999/02/26 12:46:48 simonm Exp $
*
* (c) The GHC Team, 1998-1999
*
@@ -880,9 +880,15 @@ FN_(makeStableNamezh_fast)
index = RET_STGCALL1(StgWord,lookupStableName,R1.p);
- sn_obj = (StgStableName *) (Hp - sizeofW(StgStableName) + 1);
- sn_obj->header.info = &STABLE_NAME_info;
- sn_obj->sn = index;
+ /* Is there already a StableName for this heap object? */
+ if (stable_ptr_table[index].sn_obj == NULL) {
+ sn_obj = (StgStableName *) (Hp - sizeofW(StgStableName) + 1);
+ sn_obj->header.info = &STABLE_NAME_info;
+ sn_obj->sn = index;
+ stable_ptr_table[index].sn_obj = (StgClosure *)sn_obj;
+ } else {
+ (StgClosure *)sn_obj = stable_ptr_table[index].sn_obj;
+ }
TICK_RET_UNBOXED_TUP(1);
RET_P(sn_obj);
diff --git a/ghc/rts/Stable.c b/ghc/rts/Stable.c
index 9f1414efd4f4345611ac055b735935459e63a87f..206772f3346b04f97f2f8129fb60fe423cf99193 100644
--- a/ghc/rts/Stable.c
+++ b/ghc/rts/Stable.c
@@ -1,5 +1,5 @@
/* -----------------------------------------------------------------------------
- * $Id: Stable.c,v 1.2 1999/02/05 16:02:55 simonm Exp $
+ * $Id: Stable.c,v 1.3 1999/02/26 12:46:48 simonm Exp $
*
* (c) The GHC Team, 1998-1999
*
@@ -170,6 +170,7 @@ lookupStableName(StgPtr p)
(P_)stable_ptr_free = stable_ptr_free->addr;
stable_ptr_table[sn].weight = 0;
stable_ptr_table[sn].addr = p;
+ stable_ptr_table[sn].sn_obj = NULL;
/* IF_DEBUG(stable,fprintf(stderr,"new stable name %d at
%p\n",sn,p)); */
@@ -183,6 +184,7 @@ lookupStableName(StgPtr p)
static inline void
freeStableName(snEntry *sn)
{
+ ASSERT(sn->sn_obj == NULL);
sn->addr = (P_)stable_ptr_free;
stable_ptr_free = sn;
}
@@ -266,26 +268,23 @@ markStablePtrTable(rtsBool full)
*/
for (p = stable_ptr_table; p < end_stable_ptr_table; p++) {
q = p->addr;
- /* internal pointers or NULL are free slots */
+ /* internal pointers or NULL are free slots
+ */
if (q && (q < (P_)stable_ptr_table || q >= (P_)end_stable_ptr_table)) {
if (p->weight != 0) {
new = MarkRoot((StgClosure *)q);
/* Update the hash table */
if (full) {
- insertHashTable(addrToStableHash, (W_)new, (void *)(p - stable_ptr_table));
+ insertHashTable(addrToStableHash, (W_)new,
+ (void *)(p - stable_ptr_table));
(StgClosure *)p->addr = new;
} else if ((P_)new != q) {
removeHashTable(addrToStableHash, (W_)q, NULL);
- insertHashTable(addrToStableHash, (W_)new, (void *)(p - stable_ptr_table));
+ insertHashTable(addrToStableHash, (W_)new,
+ (void *)(p - stable_ptr_table));
(StgClosure *)p->addr = new;
}
- /* IF_DEBUG(stable, fprintf(stderr,"Stable ptr %d still alive
- at %p, weight %d\n", p - stable_ptr_table, new,
- p->weight)); */
- }
- else {
- /* reset the keep flag */
- p->keep = rtsFalse;
+ IF_DEBUG(stable, fprintf(stderr,"Stable ptr %d still alive at %p, weight %d\n", p - stable_ptr_table, new, p->weight));
}
}
}
@@ -297,10 +296,12 @@ markStablePtrTable(rtsBool full)
* A dead entry has:
*
* - a weight of zero (i.e. 2^32)
- * - a false keep flag
+ * - a dead sn_obj
*
- * The keep flag is set by the garbage collector whenever it
- * encounters a StableName object on the heap.
+ * Both of these conditions must be true in order to re-use the stable
+ * name table entry. We can re-use stable name table entries for live
+ * heap objects, as long as the program has no StableName objects that
+ * refer to the entry.
*
* The boolean argument 'full' indicates that a major collection is
* being done, so we might as well throw away the hash table and build
@@ -321,36 +322,40 @@ gcStablePtrTable(rtsBool full)
end_stable_ptr_table = &stable_ptr_table[SPT_size];
for (p = stable_ptr_table; p < end_stable_ptr_table; p++) {
- q = p->addr;
+ /* Update the pointer to the StableName object, if there is one */
+ if (p->sn_obj != NULL) {
+ p->sn_obj = isAlive(p->sn_obj);
+ }
+
+ q = p->addr;
if (q && (q < (P_)stable_ptr_table || q >= (P_)end_stable_ptr_table)) {
- /* We're only interested in Stable Names here. */
+ /* We're only interested in Stable Names here. The weight != 0
+ * case is handled in markStablePtrTable above.
+ */
if (p->weight == 0) {
- if (((StgClosure *)new = isAlive((StgClosure *)q))) {
+ if (p->sn_obj == NULL) {
+ /* StableName object is dead */
+ freeStableName(p);
+ IF_DEBUG(stable, fprintf(stderr,"GC'd Stable name %d\n", p - stable_ptr_table));
+ }
+ else {
+ (StgClosure *)new = isAlive((StgClosure *)q);
IF_DEBUG(stable, fprintf(stderr,"Stable name %d still alive at %p, weight %d\n", p - stable_ptr_table, new, p->weight));
p->addr = new;
- /* Re-hash this stable name */
- if (full) {
- insertHashTable(addrToStableHash, (W_)new, (void *)(p - stable_ptr_table));
- } else if (new != q) {
- removeHashTable(addrToStableHash, (W_)q, NULL);
- insertHashTable(addrToStableHash, (W_)new, (void *)(p - stable_ptr_table));
+ if (new != NULL) {
+ /* Re-hash this stable name */
+ if (full) {
+ insertHashTable(addrToStableHash, (W_)new, (void *)(p - stable_ptr_table));
+ } else if (new != q) {
+ removeHashTable(addrToStableHash, (W_)q, NULL);
+ insertHashTable(addrToStableHash, (W_)new, (void *)(p - stable_ptr_table));
+ }
}
}
-
- else {
- /* If there are still StableName objects in the heap
- * pointing to this entry (p->keep == rtsTrue), then
- * don't free the entry just yet.
- */
- if (p->keep)
- p->addr = NULL;
- else
- freeStableName(p);
- }
}
}
}