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

src/jump-target.h

 // Copyright 2008 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 17 matching lines @@
 #ifndef V8_JUMP_TARGET_H_
 #define V8_JUMP_TARGET_H_
 
 namespace v8 { namespace internal {
 
 // Forward declarations.
 class FrameElement;
 class Result;
 class VirtualFrame;
 
-
 // -------------------------------------------------------------------------
 // Jump targets
 //
 // A jump target is an abstraction of a basic-block entry in generated
 // code.  It collects all the virtual frames reaching the block by
 // forward jumps and pairs them with labels for the merge code along
 // all forward-reaching paths.  When bound, an expected frame for the
 // block is determined and code is generated to merge to the expected
 // frame.  For backward jumps, the merge code is generated at the edge
 // leaving the predecessor block.
@@ skipping 143 matching lines @@
   void DoBranch(Condition cc, Hint hint);
   void DoBind(int mergable_elements);
 
  private:
   static bool compiling_deferred_code_;
 
   // Add a virtual frame reaching this labeled block via a forward jump,
   // and a corresponding merge code label.
   void AddReachingFrame(VirtualFrame* frame);
 
-  // Compute a frame to use for entry to this block.  Mergable elements
-  // is as described for the Bind function.
+  // Perform initialization required during entry frame computation
+  // after setting the virtual frame element at index in frame to be
+  // target.
+  inline void InitializeEntryElement(int index, FrameElement* target);
+
+  // Compute a frame to use for entry to this block.  Mergable
+  // elements is as described for the Bind function.
   void ComputeEntryFrame(int mergable_elements);
 
   DISALLOW_COPY_AND_ASSIGN(JumpTarget);
 };
 
 
 // -------------------------------------------------------------------------
 // Break targets
 //
 // A break target is a jump target that can be used to break out of a
@@ skipping 91 matching lines @@
   bool is_shadowing_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ShadowTarget);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_JUMP_TARGET_H_