Changeset 29068 in webkit

Timestamp:

Jan 1, 2008, 11:47:21 AM (18 years ago)

Author:

Darin Adler

Message:

• rolled scope chain optimization out; it was breaking the world

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• kjs/object.h (modified) (1 diff)
• kjs/scope_chain.cpp (modified) (1 diff)
• kjs/scope_chain.h (modified) (6 diffs)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2008-01-01  Darin Adler  <[email protected]>
+
+        - rolled scope chain optimization out; it was breaking the world
+
 2008-01-01  Darin Adler  <[email protected]>
 

trunk/JavaScriptCore/kjs/object.h

@@ -593 +593 @@
 }
 
+inline void ScopeChain::release()
+{
+    // This function is only called by deref(),
+    // Deref ensures these conditions are true.
+    ASSERT(_node && _node->refCount == 0);
+    ScopeChainNode *n = _node;
+    do {
+        ScopeChainNode *next = n->next;
+        delete n;
+        n = next;
+    } while (n && --n->refCount == 0);
+}
+
 inline JSValue* JSObject::toPrimitive(ExecState* exec, JSType preferredType) const
 {

trunk/JavaScriptCore/kjs/scope_chain.cpp

@@ -28 +28 @@
 namespace KJS {
 
+void ScopeChain::push(const ScopeChain &c)
+{
+    ScopeChainNode **tail = &_node;
+    for (ScopeChainNode *n = c._node; n; n = n->next) {
+        ScopeChainNode *newNode = new ScopeChainNode(*tail, n->object);
+        *tail = newNode;
+        tail = &newNode->next;
+    }
+}
+
 #ifndef NDEBUG
 

trunk/JavaScriptCore/kjs/scope_chain.h

@@ -28 +28 @@
 
     class JSObject;
-    struct ScopeChainHeapNode;
+    class ExecState;
     
-    struct ScopeChainNode {
-        JSObject* object;
-        ScopeChainHeapNode* next;
-    };
+    class ScopeChainNode {
+    public:
+        ScopeChainNode(ScopeChainNode *n, JSObject *o)
+            : next(n), object(o), refCount(1) { }
 
-    struct ScopeChainHeapNode : ScopeChainNode {
+        ScopeChainNode *next;
+        JSObject *object;
         int refCount;
     };
@@ -65 +66 @@
         ~ScopeChain() { deref(); }
 
-        ScopeChain(const ScopeChain&);
+        ScopeChain(const ScopeChain &c) : _node(c._node)
+            { if (_node) ++_node->refCount; }
         ScopeChain &operator=(const ScopeChain &);
 
@@ -78 +80 @@
         void clear() { deref(); _node = 0; }
         void push(JSObject *);
+        void push(const ScopeChain &);
         void pop();
         
@@ -87 +90 @@
         
     private:
-        mutable ScopeChainNode* _node;
-        ScopeChainNode m_initialTopNode;
-
-        ScopeChainHeapNode* moveToHeap() const;
-
-        void deref();
+        ScopeChainNode *_node;
+        
+        void deref() { if (_node && --_node->refCount == 0) release(); }
         void ref() const;
+        
+        void release();
     };
-
-inline ScopeChainHeapNode* ScopeChain::moveToHeap() const
-{
-    if (_node != &m_initialTopNode)
-        return static_cast<ScopeChainHeapNode*>(_node);
-    ScopeChainHeapNode* heapNode = new ScopeChainHeapNode;
-    heapNode->object = m_initialTopNode.object;
-    heapNode->next = m_initialTopNode.next;
-    heapNode->refCount = 1;
-    _node = heapNode;
-    return heapNode;
-}
-
-inline ScopeChain::ScopeChain(const ScopeChain& otherChain)
-{
-    if (!otherChain._node)
-        _node = 0;
-    else {
-        ScopeChainHeapNode* top = otherChain.moveToHeap();
-        ++top->refCount;
-        _node = top;
-    }
-}
 
 inline void ScopeChain::ref() const
 {
-    ASSERT(_node != &m_initialTopNode);
-    for (ScopeChainHeapNode* n = static_cast<ScopeChainHeapNode*>(_node); n; n = n->next) {
-        if (n->refCount++)
+    for (ScopeChainNode *n = _node; n; n = n->next) {
+        if (n->refCount++ != 0)
             break;
     }
 }
 
-inline void ScopeChain::deref()
+inline ScopeChain &ScopeChain::operator=(const ScopeChain &c)
 {
-    ScopeChainHeapNode* node = static_cast<ScopeChainHeapNode*>(_node);
-    if (node == &m_initialTopNode)
-        node = node->next;
-    ScopeChainHeapNode* next;
-    for (; node && --node->refCount == 0; node = next) {
-        next = node->next;
-        delete node;
-    }
-}
-
-inline ScopeChain &ScopeChain::operator=(const ScopeChain& otherChain)
-{
-    otherChain.moveToHeap();
-    otherChain.ref();
+    c.ref();
     deref();
-    _node = otherChain._node;
+    _node = c._node;
     return *this;
 }
@@ -159 +124 @@
 }
 
-inline void ScopeChain::push(JSObject* o)
+inline void ScopeChain::push(JSObject *o)
 {
     ASSERT(o);
-    ScopeChainHeapNode* heapNode = moveToHeap();
-    m_initialTopNode.object = o;
-    m_initialTopNode.next = heapNode;
-    _node = &m_initialTopNode;
+    _node = new ScopeChainNode(_node, o);
 }
 
@@ -172 +134 @@
     ScopeChainNode *oldNode = _node;
     ASSERT(oldNode);
-    ScopeChainHeapNode *newNode = oldNode->next;
+    ScopeChainNode *newNode = oldNode->next;
     _node = newNode;
-
-    if (oldNode != &m_initialTopNode) {
-        ScopeChainHeapNode* oldHeapNode = static_cast<ScopeChainHeapNode*>(oldNode);
-        if (--oldHeapNode->refCount != 0) {
-            if (newNode)
-                ++newNode->refCount;
-        } else {
-            delete oldHeapNode;
-        }
+    
+    if (--oldNode->refCount != 0) {
+        if (newNode)
+            ++newNode->refCount;
+    } else {
+        delete oldNode;
     }
 }