From cb86def1c2084f2b1c72fd04e5384d472e7cf3a0 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Thu, 16 Sep 2010 00:27:35 +0000
Subject: [PATCH] Fix a threaded LLVM bug due the need for operator= on
 reference counted AttrListImpl's.  It might be possible to implement this
 very carefully to allow a lock-free implementation while still avoiding
 illegal interleavings, but I haven't been able to figure one out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114046 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/Attributes.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/VMCore/Attributes.cpp b/lib/VMCore/Attributes.cpp
index a000aee2ab4..3422faf2730 100644
--- a/lib/VMCore/Attributes.cpp
+++ b/lib/VMCore/Attributes.cpp
@@ -195,6 +195,7 @@ AttrListPtr::AttrListPtr(const AttrListPtr &P) : AttrList(P.AttrList) {
 }
 
 const AttrListPtr &AttrListPtr::operator=(const AttrListPtr &RHS) {
+  sys::SmartScopedLock<true> Lock(*ALMutex);
   if (AttrList == RHS.AttrList) return *this;
   if (AttrList) AttrList->DropRef();
   AttrList = RHS.AttrList;
-- 
2.34.1