Changeset 43220 in webkit for trunk/JavaScriptCore/runtime/JSFunction.h

Timestamp:

May 5, 2009, 4:34:23 AM (16 years ago)

Author:

[email protected]

Message:

Bug 25559: Improve native function call performance
<​https://bugs.webkit.org/show_bug.cgi?id=25559>

Reviewed by Gavin Barraclough

In order to cache calls to native functions we now make the standard
prototype functions use a small assembly thunk that converts the JS
calling convention into the native calling convention. As this is
only beneficial in the JIT we use the NativeFunctionWrapper typedef
to alternate between PrototypeFunction and JSFunction to keep the
code sane. This change from PrototypeFunction to NativeFunctionWrapper
is the bulk of this patch.

File:

• trunk/JavaScriptCore/runtime/JSFunction.h (modified) (4 diffs)

trunk/JavaScriptCore/runtime/JSFunction.h

@@ -47 +47 @@
         JSFunction(PassRefPtr<Structure> structure)
             : InternalFunction(structure)
-            , m_scopeChain(NoScopeChain())
         {
+            clearScopeChain();
         }
 
     public:
+        JSFunction(ExecState*, PassRefPtr<Structure>, int length, const Identifier&, NativeFunction);
         JSFunction(ExecState*, const Identifier&, FunctionBodyNode*, ScopeChainNode*);
         ~JSFunction();
@@ -62 +63 @@
         JSValue call(ExecState*, JSValue thisValue, const ArgList&);
 
-        void setScope(const ScopeChain& scopeChain) { m_scopeChain = scopeChain; }
-        ScopeChain& scope() { return m_scopeChain; }
+        void setScope(const ScopeChain& scopeChain) { setScopeChain(scopeChain); }
+        ScopeChain& scope() { return scopeChain(); }
 
         void setBody(FunctionBodyNode* body) { m_body = body; }
@@ -78 +79 @@
         }
 
+#if ENABLE(JIT)
+        bool isHostFunction() const { return m_body && m_body->isHostFunction(); }
+#else
+        bool isHostFunction() const { return false; }
+#endif
     private:
         virtual const ClassInfo* classInfo() const { return &info; }
@@ -89 +95 @@
 
         RefPtr<FunctionBodyNode> m_body;
-        ScopeChain m_scopeChain;
+        ScopeChain& scopeChain()
+        {
+            ASSERT(!isHostFunction());
+            return *reinterpret_cast<ScopeChain*>(m_data);
+        }
+        void clearScopeChain()
+        {
+            ASSERT(!isHostFunction());
+            new (m_data) ScopeChain(NoScopeChain());
+        }
+        void setScopeChain(ScopeChainNode* sc)
+        {
+            ASSERT(!isHostFunction());
+            new (m_data) ScopeChain(sc);
+        }
+        void setScopeChain(const ScopeChain& sc)
+        {
+            ASSERT(!isHostFunction());
+            *reinterpret_cast<ScopeChain*>(m_data) = sc;
+        }
+        NativeFunction nativeFunction()
+        {
+            return *reinterpret_cast<NativeFunction*>(m_data);
+        }
+        void setNativeFunction(NativeFunction func)
+        {
+            *reinterpret_cast<NativeFunction*>(m_data) = func;
+        }
+        unsigned char m_data[sizeof(void*)];
     };