From 0c5277a7346657b7c8d72e4f03c96316d70d4411 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Tue, 18 Dec 2012 15:14:31 -0800
Subject: [PATCH] Bug 822700 - When DMD is disabled its SizeOf() function
 shouldn't try to measure non-existent structures.  r=jlebar.

--HG--
extra : rebase_source : 21066e5173dbc7e4a6c7615f1b355989bf046082
---
 memory/replace/dmd/DMD.cpp | 5 +++++
 memory/replace/dmd/DMD.h   | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/memory/replace/dmd/DMD.cpp b/memory/replace/dmd/DMD.cpp
index 3008ef3b13f..e22ab79bc61 100644
--- a/memory/replace/dmd/DMD.cpp
+++ b/memory/replace/dmd/DMD.cpp
@@ -1973,6 +1973,11 @@ PrintSortedBlockAndFrameGroups(const Writer& aWriter,
 MOZ_EXPORT void
 SizeOf(Sizes* aSizes)
 {
+  if (!gIsDMDRunning) {
+    aSizes->Clear();
+    return;
+  }
+
   aSizes->mStackTraces = 0;
   for (StackTraceTable::Range r = gStackTraceTable->all();
        !r.empty();
diff --git a/memory/replace/dmd/DMD.h b/memory/replace/dmd/DMD.h
index b481734c9a4..7af0e9c4859 100644
--- a/memory/replace/dmd/DMD.h
+++ b/memory/replace/dmd/DMD.h
@@ -57,7 +57,8 @@ struct Sizes
   size_t mLiveBlockTable;
   size_t mDoubleReportTable;
 
-  Sizes() { memset(this, 0, sizeof(Sizes)); }
+  Sizes() { Clear(); }
+  void Clear() { memset(this, 0, sizeof(Sizes)); }
 };
 
 // Gets the size of various data structures.  Used to implement a memory