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

src/register-allocator-ia32.h

Index: src/register-allocator-ia32.h
===================================================================
--- src/register-allocator-ia32.h	(revision 969)
+++ src/register-allocator-ia32.h	(working copy)
@@ -68,6 +68,14 @@
     }
   }
 
+  // Copy the reference counts from this register file to the other.
+  void CopyTo(RegisterFile* other);
+
+#ifdef DEBUG
+  // True if the reference counts all match the other register file.
+  bool Equals(RegisterFile* other);
+#endif
+
   static const int kNumRegisters = 8;
 
  private:
@@ -81,7 +89,7 @@
 
 class RegisterAllocator BASE_EMBEDDED {
  public:
-  RegisterAllocator(CodeGenerator* cgen) : code_generator_(cgen) {}
+  explicit RegisterAllocator(CodeGenerator* cgen) : code_generator_(cgen) {}
 
   int num_registers() const { return RegisterFile::kNumRegisters; }
 
@@ -105,6 +113,24 @@
   // no_reg.
   Register AllocateWithoutSpilling();
 
+  // Copy the internal state to a register file, to be restored later
+  // by RestoreFrom.
+  void SaveTo(RegisterFile* register_file) {
+    registers_.CopyTo(register_file);
+  }
+
+  void RestoreFrom(RegisterFile* register_file) {
+    register_file->CopyTo(&registers_);
+  }
+
+#ifdef DEBUG
+  // True if the reference counts of this allocator match those saved in the
+  // given register file.
+  bool Matches(RegisterFile* register_file) {
+    return registers_.Equals(register_file);
+  }
+#endif
+
  private:
   CodeGenerator* code_generator_;
   RegisterFile registers_;