Reduce the memory used by frame elements from two words to one by...

src/virtual-frame.cc

 // Copyright 2009 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 76 matching lines @@
       // We do not allow copies of copies, so we follow one link to
       // the actual backing store of a copy before making a copy.
       index = target.index();
       ASSERT(elements_[index].is_memory() || elements_[index].is_register());
       // Fall through.
 
     case FrameElement::MEMORY:  // Fall through.
     case FrameElement::REGISTER:
       // All copies are backed by memory or register locations.
       result.set_static_type(target.static_type());
-      result.type_ = FrameElement::COPY;
-      result.copied_ = false;
-      result.synced_ = false;
-      result.data_.index_ = index;
+      result.set_type(FrameElement::COPY);
+      result.clear_copied();
+      result.clear_sync();
+      result.set_index(index);
       elements_[index].set_copied();
       break;
 
     case FrameElement::INVALID:
       // We should not try to copy invalid elements.
       UNREACHABLE();
       break;
   }
   return result;
 }
@@ skipping 347 matching lines @@
   ASSERT(num_dropped >= 0);
   if (num_dropped == 0) return;
   Result tos = Pop();
   if (num_dropped > 1) {
     Drop(num_dropped - 1);
   }
   SetElementAt(0, &tos);
 }
 
 
-bool FrameElement::Equals(FrameElement other) {
-  if (type_ != other.type_ ||
-      copied_ != other.copied_ ||
-      synced_ != other.synced_) return false;
-
-  if (is_register()) {
-    if (!reg().is(other.reg())) return false;
-  } else if (is_constant()) {
-    if (!handle().is_identical_to(other.handle())) return false;
-  } else if (is_copy()) {
-    if (index() != other.index()) return false;
-  }
-
-  return true;
-}
-
-
 bool VirtualFrame::Equals(VirtualFrame* other) {
 #ifdef DEBUG
   // These are sanity checks in debug builds, but we do not need to
   // use them to distinguish frames at merge points.
   if (cgen_ != other->cgen_) return false;
   if (masm_ != other->masm_) return false;
   if (parameter_count_ != other->parameter_count_) return false;
   if (local_count_ != other->local_count_) return false;
   if (frame_pointer_ != other->frame_pointer_) return false;
 
@@ skipping 16 matching lines @@
 // Specialization of List::ResizeAdd to non-inlined version for FrameElements.
 // The function ResizeAdd becomes a real function, whose implementation is the
 // inlined ResizeAddInternal.
 template <>
 void List<FrameElement,
           FreeStoreAllocationPolicy>::ResizeAdd(const FrameElement& element) {
   ResizeAddInternal(element);
 }
 
 } }  // namespace v8::internal