Experimental: thread live register references to deferred code....

src/codegen.h

Index: src/codegen.h
===================================================================
--- src/codegen.h	(revision 969)
+++ src/codegen.h	(working copy)
@@ -44,6 +44,7 @@
 // shared code:
 // CodeGenerator::CodeGenerator
 // CodeGenerator::~CodeGenerator
+// CodeGenerator::SetFrame
 // CodeGenerator::ProcessDeferred
 // CodeGenerator::GenCode
 // CodeGenerator::BuildBoilerplate
@@ -81,16 +82,29 @@
 class DeferredCode: public ZoneObject {
  public:
   explicit DeferredCode(CodeGenerator* generator);
-  virtual ~DeferredCode() { }
+  virtual ~DeferredCode() {}
 
   virtual void Generate() = 0;
 
   MacroAssembler* masm() const { return masm_; }
   CodeGenerator* generator() const { return generator_; }
 
-  JumpTarget* enter() { return &enter_; }
-  JumpTarget* exit() { return &exit_; }
+  // Emit a conditional branch to the code entry.
+  void BranchTo(Condition cc);
 
+  // Bind the exit target of the code.
+  void BindExit();
+
+  // Emit an exit from the code if the exit target is bound.
+  void ExitIfBound();
+
+  Label* enter() { return &enter_; }
+
+  VirtualFrame* frame() { return frame_; }
+  void clear_frame() { frame_ = NULL; }
+
+  RegisterFile* registers() { return &registers_; }
+
   int statement_position() const { return statement_position_; }
   int position() const { return position_; }
 
@@ -110,8 +124,17 @@
 
  private:
   CodeGenerator* const generator_;
-  JumpTarget enter_;
+
+  // The entry is a label, paired with a known frame and a known global
+  // register file.  It is not a jump target because it doesn't use any of
+  // the jump target's branch or bind machinery.
+  Label enter_;
+  VirtualFrame* frame_;
+  RegisterFile registers_;
+
+  // The exit target is a regular jump target.
   JumpTarget exit_;
+
   int statement_position_;
   int position_;
 #ifdef DEBUG