Add a write buffer, aligned so that a single bit tells us whether it has...

src/assembler.cc

Index: src/assembler.cc
===================================================================
--- src/assembler.cc	(revision 6011)
+++ src/assembler.cc	(working copy)
@@ -47,6 +47,7 @@
 #include "ast.h"
 #include "regexp-macro-assembler.h"
 #include "platform.h"
+#include "write-buffer.h"
 // Include native regexp-macro-assembler.
 #ifndef V8_INTERPRETED_REGEXP
 #if V8_TARGET_ARCH_IA32
@@ -671,6 +672,11 @@
 }
 
 
+ExternalReference ExternalReference::write_buffer_top() {
+  return ExternalReference(WriteBuffer::Top());
+}
+
+
 ExternalReference ExternalReference::new_space_mask() {
   return ExternalReference(reinterpret_cast<Address>(Heap::NewSpaceMask()));
 }