Use a separate marker value to allocate the arguments object on deoptimzation...

src/x64/codegen-x64.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 609 matching lines @@
       : LAZY_ARGUMENTS_ALLOCATION;
 }
 
 
 Result CodeGenerator::StoreArgumentsObject(bool initial) {
   ArgumentsAllocationMode mode = ArgumentsMode();
   ASSERT(mode != NO_ARGUMENTS_ALLOCATION);
 
   Comment cmnt(masm_, "[ store arguments object");
   if (mode == LAZY_ARGUMENTS_ALLOCATION && initial) {
-    // When using lazy arguments allocation, we store the hole value
+    // When using lazy arguments allocation, we store the arguments marker value
     // as a sentinel indicating that the arguments object hasn't been
     // allocated yet.
-    frame_->Push(Factory::the_hole_value());
+    frame_->Push(Factory::arguments_marker());
   } else {
     ArgumentsAccessStub stub(ArgumentsAccessStub::NEW_OBJECT);
     frame_->PushFunction();
     frame_->PushReceiverSlotAddress();
     frame_->Push(Smi::FromInt(scope()->num_parameters()));
     Result result = frame_->CallStub(&stub, 3);
     frame_->Push(&result);
   }
 
   Variable* arguments = scope()->arguments();
   Variable* shadow = scope()->arguments_shadow();
   ASSERT(arguments != NULL && arguments->AsSlot() != NULL);
   ASSERT(shadow != NULL && shadow->AsSlot() != NULL);
   JumpTarget done;
   bool skip_arguments = false;
   if (mode == LAZY_ARGUMENTS_ALLOCATION && !initial) {
     // We have to skip storing into the arguments slot if it has
     // already been written to. This can happen if the a function
     // has a local variable named 'arguments'.
     LoadFromSlot(arguments->AsSlot(), NOT_INSIDE_TYPEOF);
     Result probe = frame_->Pop();
     if (probe.is_constant()) {
       // We have to skip updating the arguments object if it has
       // been assigned a proper value.
-      skip_arguments = !probe.handle()->IsTheHole();
+      skip_arguments = !probe.handle()->IsArgumentsMarker();
     } else {
-      __ CompareRoot(probe.reg(), Heap::kTheHoleValueRootIndex);
+      __ CompareRoot(probe.reg(), Heap::kArgumentsMarkerRootIndex);
       probe.Unuse();
       done.Branch(not_equal);
     }
   }
   if (!skip_arguments) {
     StoreToSlot(arguments->AsSlot(), NOT_CONST_INIT);
     if (mode == LAZY_ARGUMENTS_ALLOCATION) done.Bind();
   }
   StoreToSlot(shadow->AsSlot(), NOT_CONST_INIT);
   return frame_->Pop();
@@ skipping 1838 matching lines @@
   // Check if the arguments object has been lazily allocated
   // already. If so, just use that instead of copying the arguments
   // from the stack. This also deals with cases where a local variable
   // named 'arguments' has been introduced.
   frame_->Dup();
   Result probe = frame_->Pop();
   { VirtualFrame::SpilledScope spilled_scope;
     Label slow, done;
     bool try_lazy = true;
     if (probe.is_constant()) {
-      try_lazy = probe.handle()->IsTheHole();
+      try_lazy = probe.handle()->IsArgumentsMarker();
     } else {
-      __ CompareRoot(probe.reg(), Heap::kTheHoleValueRootIndex);
+      __ CompareRoot(probe.reg(), Heap::kArgumentsMarkerRootIndex);
       probe.Unuse();
       __ j(not_equal, &slow);
     }
 
     if (try_lazy) {
       Label build_args;
       // Get rid of the arguments object probe.
       frame_->Drop();  // Can be called on a spilled frame.
       // Stack now has 3 elements on it.
       // Contents of stack at this point:
@@ skipping 1878 matching lines @@
 
   // ... or if the slot isn't a non-parameter arguments slot.
   if (slot->type() == Slot::PARAMETER || !slot->is_arguments()) return;
 
   // Pop the loaded value from the stack.
   Result value = frame_->Pop();
 
   // If the loaded value is a constant, we know if the arguments
   // object has been lazily loaded yet.
   if (value.is_constant()) {
-    if (value.handle()->IsTheHole()) {
+    if (value.handle()->IsArgumentsMarker()) {
       Result arguments = StoreArgumentsObject(false);
       frame_->Push(&arguments);
     } else {
       frame_->Push(&value);
     }
     return;
   }
 
   // The loaded value is in a register. If it is the sentinel that
   // indicates that we haven't loaded the arguments object yet, we
   // need to do it now.
   JumpTarget exit;
-  __ CompareRoot(value.reg(), Heap::kTheHoleValueRootIndex);
+  __ CompareRoot(value.reg(), Heap::kArgumentsMarkerRootIndex);
   frame_->Push(&value);
   exit.Branch(not_equal);
   Result arguments = StoreArgumentsObject(false);
   frame_->SetElementAt(0, &arguments);
   exit.Bind();
 }
 
 
 Result CodeGenerator::LoadFromGlobalSlotCheckExtensions(
     Slot* slot,
@@ skipping 4360 matching lines @@
 }
 
 #endif
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64