Changeset 27126 in webkit for trunk/JavaScriptCore/kjs/nodes.cpp

Timestamp:

Oct 26, 2007, 3:43:03 PM (18 years ago)

Author:

ggaren

Message:

Reviewed by Maciej Stachowiak.

Switched ActivationImp to using a symbol table. For now, though, all
clients take the slow path.

Net .6% speedup on SunSpider.

Slowdowns:

• ActivationImp now mallocs in its constructor
• Local variable hits use an extra level of indirection to retrieve data
• Local variable misses do two lookups

Speedups:

• Fast initialization of local variables upon function entry

• JavaScriptCore.xcodeproj/project.pbxproj: Added SymbolTable.h

• kjs/function.cpp: (KJS::ActivationImp::ActivationImp): Malloc a private structure to hold data that won't fit in a JSCell. (KJS::ActivationImp::argumentsGetter): Use slow symbol table path for lookup. (KJS::ActivationImp::getOwnPropertySlot): ditto (KJS::ActivationImp::deleteProperty): ditto (KJS::ActivationImp::put): ditto (KJS::ActivationImp::createArgumentsObject): ditto

(KJS::ActivationImp::mark): Call JSObject::mark first so that one of
our properties doesn't try to recursively mark us. (This caused a crash
in earlier testing. Not sure why we haven't run into it before.)

• kjs/nodes.cpp: Functions now build a symbol table the first time they're called. (KJS::VarDeclNode::evaluate): (KJS::FunctionBodyNode::FunctionBodyNode): (KJS::FunctionBodyNode::initializeSymbolTable): (KJS::FunctionBodyNode::processDeclarations): (KJS::FunctionBodyNode::processDeclarationsForFunctionCode): (KJS::FunctionBodyNode::processDeclarationsForProgramCode):

• kjs/nodes.h: (KJS::FunctionBodyNode::symbolTable):

• wtf/Forward.h: Added Vector.

File:

• trunk/JavaScriptCore/kjs/nodes.cpp (modified) (5 diffs)

trunk/JavaScriptCore/kjs/nodes.cpp

@@ -1835 +1835 @@
             flags |= ReadOnly;
         
-        ASSERT(variableObject->getDirect(ident) || ident == exec->propertyNames().arguments);
+        ASSERT(variableObject->hasProperty(exec, ident));
         variableObject->put(exec, ident, val, flags);
     }
@@ -2579 +2579 @@
     , m_sourceId(Parser::sid)
     , m_initializedDeclarationStacks(false)
+    , m_initializedSymbolTable(false)
 {
   setLoc(-1, -1);
@@ -2607 +2608 @@
 }
 
-void FunctionBodyNode::processDeclarationsFunctionCode(ExecState* exec)
+void FunctionBodyNode::initializesymbolTable()
 {
     size_t i, size;
-
-    JSObject* variableObject = exec->variableObject();
-
+    size_t count = 0;
+
+    // The order of additions here implicitly enforces the mutual exclusion described in ECMA 10.1.3.
+    for (i = 0, size = m_varStack.size(); i < size; ++i)
+        m_symbolTable.set(m_varStack[i]->ident, count++);
+
+    for (i = 0, size = m_parameters.size(); i < size; ++i)
+        m_symbolTable.set(m_parameters[i], count++);
+
+    for (i = 0, size = m_functionStack.size(); i < size; ++i)
+        m_symbolTable.set(m_functionStack[i]->ident, count++);
+
+    m_initializedSymbolTable = true;
+}
+
+void FunctionBodyNode::processDeclarations(ExecState* exec)
+{
+    if (!m_initializedDeclarationStacks)
+        initializeDeclarationStacks(exec);
+
+    if (exec->codeType() == FunctionCode)
+        processDeclarationsForFunctionCode(exec);
+    else
+        processDeclarationsForProgramCode(exec);
+}
+
+void FunctionBodyNode::processDeclarationsForFunctionCode(ExecState* exec)
+{
+    if (!m_initializedSymbolTable)
+        initializesymbolTable();
+
+    ASSERT(exec->variableObject()->isActivation());
+    ActivationImp::LocalStorage& localStorage = static_cast<ActivationImp*>(exec->variableObject())->localStorage();
+    localStorage.reserveCapacity(m_varStack.size() + m_parameters.size() + m_functionStack.size());
+    
     int minAttributes = Internal | DontDelete;
-
-    // The order of additions to the variable object here implicitly enforces the mutual exclusion described in ECMA 10.1.3.
+    
+    size_t i, size;
+
+    // NOTE: Must match the order of addition in initializesymbolTable().
+
     for (i = 0, size = m_varStack.size(); i < size; ++i) {
         VarDeclNode* node = m_varStack[i];
@@ -2621 +2657 @@
         if (node->varType == VarDeclNode::Constant)
             attributes |= ReadOnly;
-        variableObject->put(exec, node->ident, jsUndefined(), attributes);
+        localStorage.append(ActivationImp::LocalStorageEntry(jsUndefined(), attributes));
     }
 
     const List& args = *exec->arguments();
     for (i = 0, size = m_parameters.size(); i < size; ++i)
-        variableObject->put(exec, m_parameters[i], args[i], DontDelete);
+        localStorage.append(ActivationImp::LocalStorageEntry(args[i], DontDelete));
 
     for (i = 0, size = m_functionStack.size(); i < size; ++i) {
         FuncDeclNode* node = m_functionStack[i];
-        variableObject->put(exec, node->ident, node->makeFunction(exec), minAttributes);
+        localStorage.append(ActivationImp::LocalStorageEntry(node->makeFunction(exec), minAttributes));
     }
 }
 
-void FunctionBodyNode::processDeclarationsProgramCode(ExecState* exec)
+void FunctionBodyNode::processDeclarationsForProgramCode(ExecState* exec)
 {
     size_t i, size;
@@ -2678 +2714 @@
 }
 
-void FunctionBodyNode::processDeclarations(ExecState* exec)
-{
-    if (!m_initializedDeclarationStacks)
-        initializeDeclarationStacks(exec);
-
-    if (exec->codeType() == FunctionCode)
-        processDeclarationsFunctionCode(exec);
-    else
-        processDeclarationsProgramCode(exec);
-}
-
 Completion FunctionBodyNode::execute(ExecState* exec)
 {