Bug 1226687 - Part 2: Use stable hashing and builtin sweep for JSObject2JSObjectMap; r=mccr8

--HG--
extra : rebase_source : e3c5c05bead56da0dab01a3fdfb16a1f02fe862d

js/xpconnect/src/XPCMaps.h

@@ -11,6 +11,7 @@
 
 #include "mozilla/MemoryReporting.h"
 
+#include "js/GCHashTable.h"
 
 // Maps...
 
@@ -593,8 +594,10 @@ private:
 
 class JSObject2JSObjectMap
 {
-    typedef js::HashMap<JSObject*, JS::Heap<JSObject*>, js::PointerHasher<JSObject*, 3>,
+    using Map = js::GCHashMap<JS::Heap<JSObject*>,
-                        js::SystemAllocPolicy> Map;
+                              JS::Heap<JSObject*>,
+                              js::MovableCellHasher<JS::Heap<JSObject*>>,
+                              js::SystemAllocPolicy>;
 
 public:
     static JSObject2JSObjectMap* newMap(int length) {
@@ -624,7 +627,6 @@ public:
         if (!mTable.add(p, key, value))
             return nullptr;
         MOZ_ASSERT(xpc::CompartmentPrivate::Get(key)->scope->mWaiverWrapperMap == this);
-        JS_StoreObjectPostBarrierCallback(cx, KeyMarkCallback, key, this);
         return value;
     }
 
@@ -636,41 +638,12 @@ public:
     inline uint32_t Count() { return mTable.count(); }
 
     void Sweep() {
-        for (Map::Enum e(mTable); !e.empty(); e.popFront()) {
+        mTable.sweep();
-            JSObject* key = e.front().key();
-            JS::Heap<JSObject*>* valuep = &e.front().value();
-            JS_UpdateWeakPointerAfterGCUnbarriered(&key);
-            JS_UpdateWeakPointerAfterGC(valuep);
-            if (!key || !*valuep)
-                e.removeFront();
-            else if (key != e.front().key())
-                e.rekeyFront(key);
-        }
     }
 
 private:
     JSObject2JSObjectMap() {}
 
-    /*
-     * This function is called during minor GCs for each key in the HashMap that
-     * has been moved.
-     */
-    static void KeyMarkCallback(JSTracer* trc, JSObject* key, void* data) {
-        /*
-         * To stop the barriers on the values of mTable firing while we are
-         * marking the store buffer, we cast the table to one that is
-         * binary-equivatlent but without the barriers, and update that.
-         */
-        typedef js::HashMap<JSObject*, JSObject*, js::PointerHasher<JSObject*, 3>,
-                            js::SystemAllocPolicy> UnbarrieredMap;
-        JSObject2JSObjectMap* self = static_cast<JSObject2JSObjectMap*>(data);
-        UnbarrieredMap& table = reinterpret_cast<UnbarrieredMap&>(self->mTable);
-
-        JSObject* prior = key;
-        JS_CallUnbarrieredObjectTracer(trc, &key, "XPCWrappedNativeScope::mWaiverWrapperMap key");
-        table.rekeyIfMoved(prior, key);
-    }
-
     Map mTable;
 };