Always iterate outgoing arguments as a part of caller frame.

Change caller_sp() to always point to the place after outgoing arguments.

Review URL: http://codereview.chromium.org/6720049

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7504 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/frames-inl.h

@@ -148,15 +148,26 @@ inline bool StandardFrame::IsConstructFrame(Address fp) {
 }
 
 
+Address JavaScriptFrame::GetParameterSlot(int index) const {
+  int param_count = ComputeParametersCount();
+  ASSERT(-1 <= index && index < param_count);
+  int parameter_offset = (param_count - index - 1) * kPointerSize;
+  return caller_sp() + parameter_offset;
+}
+
+
+Object* JavaScriptFrame::GetParameter(int index) const {
+  return Memory::Object_at(GetParameterSlot(index));
+}
+
+
 inline Object* JavaScriptFrame::receiver() const {
-  const int offset = JavaScriptFrameConstants::kReceiverOffset;
-  return Memory::Object_at(caller_sp() + offset);
+  return GetParameter(-1);
 }
 
 
 inline void JavaScriptFrame::set_receiver(Object* value) {
-  const int offset = JavaScriptFrameConstants::kReceiverOffset;
-  Memory::Object_at(caller_sp() + offset) = value;
+  Memory::Object_at(GetParameterSlot(-1)) = value;
 }
 
 

src/frames.cc

@@ -579,9 +579,7 @@ void OptimizedFrame::Iterate(ObjectVisitor* v) const {
       isolate(), pc(), &safepoint_entry, &stack_slots);
   unsigned slot_space = stack_slots * kPointerSize;
 
-  // Visit the outgoing parameters. This is usually dealt with by the
-  // callee, but while GC'ing we artificially lower the number of
-  // arguments to zero and let the caller deal with it.
+  // Visit the outgoing parameters.
   Object** parameters_base = &Memory::Object_at(sp());
   Object** parameters_limit = &Memory::Object_at(
       fp() + JavaScriptFrameConstants::kFunctionOffset - slot_space);
@@ -635,21 +633,6 @@ void OptimizedFrame::Iterate(ObjectVisitor* v) const {
 
   // Visit the return address in the callee and incoming arguments.
   IteratePc(v, pc_address(), code);
-  IterateArguments(v);
-}
-
-
-Object* JavaScriptFrame::GetParameter(int index) const {
-  ASSERT(index >= 0 && index < ComputeParametersCount());
-  const int offset = JavaScriptFrameConstants::kParam0Offset;
-  return Memory::Object_at(caller_sp() + offset - (index * kPointerSize));
-}
-
-
-int JavaScriptFrame::ComputeParametersCount() const {
-  Address base  = caller_sp() + JavaScriptFrameConstants::kReceiverOffset;
-  Address limit = fp() + JavaScriptFrameConstants::kLastParameterOffset;
-  return static_cast<int>((base - limit) / kPointerSize);
 }
 
 
@@ -669,27 +652,17 @@ Code* JavaScriptFrame::unchecked_code() const {
 }
 
 
-Address JavaScriptFrame::GetCallerStackPointer() const {
-  int arguments;
-  if (SafeStackFrameIterator::is_active(isolate()) ||
-      isolate()->heap()->gc_state() != Heap::NOT_IN_GC) {
-    // If the we are currently iterating the safe stack the
-    // arguments for frames are traversed as if they were
-    // expression stack elements of the calling frame. The reason for
-    // this rather strange decision is that we cannot access the
-    // function during mark-compact GCs when objects may have been marked.
-    // In fact accessing heap objects (like function->shared() below)
-    // at all during GC is problematic.
-    arguments = 0;
-  } else {
-    // Compute the number of arguments by getting the number of formal
-    // parameters of the function. We must remember to take the
-    // receiver into account (+1).
+int JavaScriptFrame::GetNumberOfIncomingArguments() const {
+  ASSERT(!SafeStackFrameIterator::is_active(isolate()) &&
+         isolate()->heap()->gc_state() == Heap::NOT_IN_GC);
+
   JSFunction* function = JSFunction::cast(this->function());
-    arguments = function->shared()->formal_parameter_count() + 1;
-  }
-  const int offset = StandardFrameConstants::kCallerSPOffset;
-  return fp() + offset + (arguments * kPointerSize);
+  return function->shared()->formal_parameter_count();
+}
+
+
+Address JavaScriptFrame::GetCallerStackPointer() const {
+  return fp() + StandardFrameConstants::kCallerSPOffset;
 }
 
 
@@ -867,9 +840,7 @@ void OptimizedFrame::GetFunctions(List<JSFunction*>* functions) {
 
 
 Address ArgumentsAdaptorFrame::GetCallerStackPointer() const {
-  const int arguments = Smi::cast(GetExpression(0))->value();
-  const int offset = StandardFrameConstants::kCallerSPOffset;
-  return fp() + offset + (arguments + 1) * kPointerSize;
+  return fp() + StandardFrameConstants::kCallerSPOffset;
 }
 
 
@@ -1109,17 +1080,6 @@ void StandardFrame::IterateExpressions(ObjectVisitor* v) const {
 void JavaScriptFrame::Iterate(ObjectVisitor* v) const {
   IterateExpressions(v);
   IteratePc(v, pc_address(), LookupCode());
-  IterateArguments(v);
-}
-
-
-void JavaScriptFrame::IterateArguments(ObjectVisitor* v) const {
-  // Traverse callee-saved registers, receiver, and parameters.
-  const int kBaseOffset = JavaScriptFrameConstants::kLastParameterOffset;
-  const int kLimitOffset = JavaScriptFrameConstants::kReceiverOffset;
-  Object** base = &Memory::Object_at(fp() + kBaseOffset);
-  Object** limit = &Memory::Object_at(caller_sp() + kLimitOffset) + 1;
-  v->VisitPointers(base, limit);
 }
 
 

src/frames.h

@@ -463,8 +463,11 @@ class JavaScriptFrame: public StandardFrame {
   inline void set_receiver(Object* value);
 
   // Access the parameters.
-  Object* GetParameter(int index) const;
-  int ComputeParametersCount() const;
+  inline Address GetParameterSlot(int index) const;
+  inline Object* GetParameter(int index) const;
+  inline int ComputeParametersCount() const {
+    return GetNumberOfIncomingArguments();
+  }
 
   // Check if this frame is a constructor frame invoked through 'new'.
   bool IsConstructor() const;
@@ -502,6 +505,8 @@ class JavaScriptFrame: public StandardFrame {
 
   virtual Address GetCallerStackPointer() const;
 
+  virtual int GetNumberOfIncomingArguments() const;
+
   // Garbage collection support. Iterates over incoming arguments,
   // receiver, and any callee-saved registers.
   void IterateArguments(ObjectVisitor* v) const;
@@ -562,6 +567,10 @@ class ArgumentsAdaptorFrame: public JavaScriptFrame {
   explicit ArgumentsAdaptorFrame(StackFrameIterator* iterator)
       : JavaScriptFrame(iterator) { }
 
+  virtual int GetNumberOfIncomingArguments() const {
+     return Smi::cast(GetExpression(0))->value();
+  }
+
   virtual Address GetCallerStackPointer() const;
 
  private: