From 9d43ff71b8693149a78bbd4057834d94f4c1d254 Mon Sep 17 00:00:00 2001
From: "danno@chromium.org"
 <danno@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Thu, 18 Oct 2012 12:01:36 +0000
Subject: [PATCH] Avoid unnecessary code target changes during code compaction.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/11198032

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12754 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/mark-compact.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 0740ca04a8..7a25855d53 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -2315,8 +2315,13 @@ class PointersUpdatingVisitor: public ObjectVisitor {
   void VisitEmbeddedPointer(RelocInfo* rinfo) {
     ASSERT(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT);
     Object* target = rinfo->target_object();
+    Object* old_target = target;
     VisitPointer(&target);
-    rinfo->set_target_object(target);
+    // Avoid unnecessary changes that might unnecessary flush the instruction
+    // cache.
+    if (target != old_target) {
+      rinfo->set_target_object(target);
+    }
   }
 
   void VisitCodeTarget(RelocInfo* rinfo) {