From 67bb9a7c716b27a274080b28799f7e64f89facd7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Lindqvist?= <bjourne@gmail.com>
Date: Fri, 14 Oct 2016 13:50:47 +0200
Subject: [PATCH] VM: checking addresses differ before memmoving

It appears to speed up compaction a bit in cases where only a few
objects need to move.
---
 vm/free_list.hpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/vm/free_list.hpp b/vm/free_list.hpp
index a93084315b..d19dea5b15 100644
--- a/vm/free_list.hpp
+++ b/vm/free_list.hpp
@@ -279,7 +279,9 @@ void free_list_allocator<Block>::compact(Iterator& iter, Fixup fixup,
     if (!state.marked_p(block_addr))
       return;
     *finger = (Block*)(block_addr + size);
-    memmove((Block*)dest_addr, block, size);
+    if (dest_addr != (cell)block) {
+      memmove((Block*)dest_addr, block, size);
+    }
     iter(block, (Block*)dest_addr, size);
     dest_addr += size;
   };