Changeset 43559 in webkit for trunk/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

Timestamp:

May 12, 2009, 1:58:56 AM (16 years ago)

Author:

[email protected]

Message:

Improve function call forwarding performance

Reviewed by Gavin Barraclough

Make creation of the Arguments object occur lazily, so it
is not necessarily created for every function that references
it. Then add logic to Function.apply to allow it to avoid
allocating the Arguments object at all. Helps a lot with
the function forwarding/binding logic in jQuery, Prototype,
and numerous other JS libraries.

File:

• trunk/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp (modified) (4 diffs)

trunk/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@ -333 +333 @@
         emitOpcode(op_enter);
 
-    if (usesArguments)
-        emitOpcode(op_create_arguments);
+     if (usesArguments)
+        emitOpcode(op_init_arguments);
 
     const DeclarationStacks::FunctionStack& functionStack = functionBody->functionStack();
@@ -429 +429 @@
         return 0;
 
+    if (ident == propertyNames().arguments)
+        createArgumentsIfNecessary();
+
+    return &registerFor(entry.getIndex());
+}
+
+bool BytecodeGenerator::willResolveToArguments(const Identifier& ident)
+{
+    if (ident != propertyNames().arguments)
+        return false;
+    
+    if (!shouldOptimizeLocals())
+        return false;
+    
+    SymbolTableEntry entry = symbolTable().get(ident.ustring().rep());
+    if (entry.isNull())
+        return false;
+    
+    if (m_codeBlock->usesArguments() && m_codeType == FunctionCode)
+        return true;
+    
+    return false;
+}
+
+RegisterID* BytecodeGenerator::uncheckedRegisterForArguments()
+{
+    ASSERT(willResolveToArguments(propertyNames().arguments));
+
+    SymbolTableEntry entry = symbolTable().get(propertyNames().arguments.ustring().rep());
+    ASSERT(!entry.isNull());
     return &registerFor(entry.getIndex());
 }
@@ -1347 +1377 @@
 }
 
+void BytecodeGenerator::createArgumentsIfNecessary()
+{
+    if (m_codeBlock->usesArguments() && m_codeType == FunctionCode)
+        emitOpcode(op_create_arguments);
+}
+
 RegisterID* BytecodeGenerator::emitCallEval(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode* argumentsNode, unsigned divot, unsigned startOffset, unsigned endOffset)
 {
+    createArgumentsIfNecessary();
     return emitCall(op_call_eval, dst, func, thisRegister, argumentsNode, divot, startOffset, endOffset);
 }
@@ -1573 +1610 @@
     m_scopeContextStack.append(context);
     m_dynamicScopeDepth++;
+    createArgumentsIfNecessary();
 
     return emitUnaryNoDstOp(op_push_scope, scope);