Bug 745322 - Make a relocatable version of HeapId; r=billm

We cannot put implicitly post-barriered items into memory managed outside the
GC.

--HG--
extra : rebase_source : 9d4c8db78d887642dd06e60788e9d514040e92e4

js/src/gc/Barrier-inl.h

@@ -313,30 +313,8 @@ HeapSlot::post(JSCompartment *comp, JSObject *owner, uint32_t slot)
     HeapSlot::writeBarrierPost(comp, owner, slot);
 }
 
-inline
-HeapId::HeapId(jsid id)
-    : value(id)
-{
-    JS_ASSERT(!IsPoisonedId(id));
-    post();
-}
-
-inline
-HeapId::~HeapId()
-{
-    pre();
-}
-
 inline void
-HeapId::init(jsid id)
-{
-    JS_ASSERT(!IsPoisonedId(id));
-    value = id;
-    post();
-}
-
-inline void
-HeapId::pre()
+EncapsulatedId::pre()
 {
 #ifdef JSGC_INCREMENTAL
     if (JSID_IS_OBJECT(value)) {
@@ -357,6 +335,54 @@ HeapId::pre()
 #endif
 }
 
+inline
+RelocatableId::~RelocatableId()
+{
+    pre();
+}
+
+inline RelocatableId &
+RelocatableId::operator=(jsid id)
+{
+    if (id != value)
+        pre();
+    JS_ASSERT(!IsPoisonedId(id));
+    value = id;
+    return *this;
+}
+
+inline RelocatableId &
+RelocatableId::operator=(const RelocatableId &v)
+{
+    if (v.value != value)
+        pre();
+    JS_ASSERT(!IsPoisonedId(v.value));
+    value = v.value;
+    return *this;
+}
+
+inline
+HeapId::HeapId(jsid id)
+    : EncapsulatedId(id)
+{
+    JS_ASSERT(!IsPoisonedId(id));
+    post();
+}
+
+inline
+HeapId::~HeapId()
+{
+    pre();
+}
+
+inline void
+HeapId::init(jsid id)
+{
+    JS_ASSERT(!IsPoisonedId(id));
+    value = id;
+    post();
+}
+
 inline void
 HeapId::post()
 {

js/src/gc/Barrier.h

@@ -443,21 +443,20 @@ class HeapSlotArray
     HeapSlotArray operator +(uint32_t offset) const { return HeapSlotArray(array + offset); }
 };
 
-class HeapId
+class EncapsulatedId
 {
+  protected:
     jsid value;
 
+    explicit EncapsulatedId() : value(JSID_VOID) {}
+    explicit inline EncapsulatedId(jsid id) : value(id) {}
+    ~EncapsulatedId() {}
+
+  private:
+    EncapsulatedId(const EncapsulatedId &v) MOZ_DELETE;
+    EncapsulatedId &operator=(const EncapsulatedId &v) MOZ_DELETE;
+
   public:
-    explicit HeapId() : value(JSID_VOID) {}
-    explicit inline HeapId(jsid id);
-
-    inline ~HeapId();
-
-    inline void init(jsid id);
-
-    inline HeapId &operator=(jsid id);
-    inline HeapId &operator=(const HeapId &v);
-
     bool operator==(jsid id) const { return value == id; }
     bool operator!=(jsid id) const { return value != id; }
 
@@ -465,11 +464,37 @@ class HeapId
     jsid *unsafeGet() { return &value; }
     operator jsid() const { return value; }
 
-  private:
+  protected:
     inline void pre();
+};
+
+class RelocatableId : public EncapsulatedId
+{
+  public:
+    explicit RelocatableId() : EncapsulatedId() {}
+    explicit inline RelocatableId(jsid id) : EncapsulatedId(id) {}
+    inline ~RelocatableId();
+
+    inline RelocatableId &operator=(jsid id);
+    inline RelocatableId &operator=(const RelocatableId &v);
+};
+
+class HeapId : public EncapsulatedId
+{
+  public:
+    explicit HeapId() : EncapsulatedId() {}
+    explicit inline HeapId(jsid id);
+    inline ~HeapId();
+
+    inline void init(jsid id);
+
+    inline HeapId &operator=(jsid id);
+    inline HeapId &operator=(const HeapId &v);
+
+  private:
     inline void post();
 
-    HeapId(const HeapId &v);
+    HeapId(const HeapId &v) MOZ_DELETE;
 };
 
 /*

js/src/jsgcmark.cpp

@@ -283,7 +283,7 @@ MarkIdInternal(JSTracer *trc, jsid *id)
 }
 
 void
-MarkId(JSTracer *trc, HeapId *id, const char *name)
+MarkId(JSTracer *trc, EncapsulatedId *id, const char *name)
 {
     JS_SET_TRACING_NAME(trc, name);
     MarkIdInternal(trc, id->unsafeGet());

js/src/jsgcmark.h

@@ -84,13 +84,13 @@ MarkGCThingRoot(JSTracer *trc, void **thingp, const char *name);
 /*** ID Marking ***/
 
 void
-MarkId(JSTracer *trc, HeapId *id, const char *name);
+MarkId(JSTracer *trc, EncapsulatedId *id, const char *name);
 
 void
 MarkIdRoot(JSTracer *trc, jsid *id, const char *name);
 
 void
-MarkIdRange(JSTracer *trc, size_t len, js::HeapId *vec, const char *name);
+MarkIdRange(JSTracer *trc, size_t len, HeapId *vec, const char *name);
 
 void
 MarkIdRootRange(JSTracer *trc, size_t len, jsid *vec, const char *name);