Changeset 10168 in webkit for trunk/JavaScriptCore/kjs/nodes.cpp

Timestamp:

Aug 12, 2005, 4:20:48 PM (20 years ago)

Author:

mjs

Message:

Reviewed by John.

• two simple speed improvements for a 3% speed gain

• JavaScriptCore.xcodeproj/project.pbxproj: turn on -fstrict-aliasing

• kjs/scope_chain.h: (KJS::ScopeChainIterator::ScopeChainIterator): Add a scope chain iterator so you can walk a scope chain without having to make a copy that you then mutate. (KJS::ScopeChainIterator::operator*): standard iterator operation (KJS::ScopeChainIterator::operator->): ditto (KJS::ScopeChainIterator::operator++): ditto (KJS::ScopeChainIterator::operator==): ditto (KJS::ScopeChainIterator::operator!=): ditto (KJS::ScopeChain::begin): Iterator for the top of the scope chain (KJS::ScopeChain::end): Iterator for one past the bottom (i.e. null)
• kjs/nodes.cpp: (ResolveNode::evaluate): Use scope chain iterator instead of copying a scope chain and then modifying the copy (ResolveNode::evaluateReference): ditto (FunctionCallResolveNode::evaluate): ditto (AssignResolveNode::evaluate): ditto

File:

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

trunk/JavaScriptCore/kjs/nodes.cpp

@@ -334 +334 @@
 ValueImp *ResolveNode::evaluate(ExecState *exec)
 {
-  ScopeChain chain = exec->context().imp()->scopeChain();
-
-  assert(!chain.isEmpty());
+  const ScopeChain& chain = exec->context().imp()->scopeChain();
+  ScopeChainIterator iter = chain.begin();
+  ScopeChainIterator end = chain.end();
+  
+  // we must always have something in the scope chain
+  assert(iter != end);
 
   PropertySlot slot;
   do { 
-    ObjectImp *o = chain.top();
+    ObjectImp *o = *iter;
 
     if (o->getPropertySlot(exec, ident, slot))
       return slot.getValue(exec, ident);
     
-    chain.pop();
-  } while (!chain.isEmpty());
+    ++iter;
+  } while (iter != end);
 
   return undefinedVariableError(exec, ident);
@@ -353 +356 @@
 Reference ResolveNode::evaluateReference(ExecState *exec)
 {
-  ScopeChain chain = exec->context().imp()->scopeChain();
-
-  assert(!chain.isEmpty());
+  const ScopeChain& chain = exec->context().imp()->scopeChain();
+  ScopeChainIterator iter = chain.begin();
+  ScopeChainIterator end = chain.end();
+  
+  // we must always have something in the scope chain
+  assert(iter != end);
 
   PropertySlot slot;
   do { 
-    ObjectImp *o = chain.top();
+    ObjectImp *o = *iter;
     if (o->getPropertySlot(exec, ident, slot))
       return Reference(o, ident);
     
-    chain.pop();
-  } while (!chain.isEmpty());
+    ++iter;
+  } while (iter != end);
 
   return Reference(ident);
@@ -818 +824 @@
 ValueImp *FunctionCallResolveNode::evaluate(ExecState *exec)
 {
-  ScopeChain chain = exec->context().imp()->scopeChain();
-
-  assert(!chain.isEmpty());
+  const ScopeChain& chain = exec->context().imp()->scopeChain();
+  ScopeChainIterator iter = chain.begin();
+  ScopeChainIterator end = chain.end();
+  
+  // we must always have something in the scope chain
+  assert(iter != end);
 
   PropertySlot slot;
   ObjectImp *base;
   do { 
-    base = chain.top();
+    base = *iter;
     if (base->getPropertySlot(exec, ident, slot)) {
       ValueImp *v = slot.getValue(exec, ident);
@@ -855 +864 @@
       return func->call(exec, thisObj, argList);
     }
-    chain.pop();
-  } while (!chain.isEmpty());
+    ++iter;
+  } while (iter != end);
   
   return undefinedVariableError(exec, ident);
@@ -1680 +1689 @@
 ValueImp *AssignResolveNode::evaluate(ExecState *exec)
 {
-  ScopeChain chain = exec->context().imp()->scopeChain();
-
-  assert(!chain.isEmpty());
+  const ScopeChain& chain = exec->context().imp()->scopeChain();
+  ScopeChainIterator iter = chain.begin();
+  ScopeChainIterator end = chain.end();
+  
+  // we must always have something in the scope chain
+  assert(iter != end);
 
   PropertySlot slot;
   ObjectImp *base;
   do { 
-    base = chain.top();
+    base = *iter;
     if (base->getPropertySlot(exec, m_ident, slot))
       goto found;
 
-    chain.pop();
-  } while (!chain.isEmpty());
+    ++iter;
+  } while (iter != end);
 
   if (m_oper != OpEqual)