From 2e831897d61a46ad627f16da00ec522c5a38b72d Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Thu, 18 Nov 2010 18:59:13 +0000
Subject: [PATCH] Fix an order-of-deallocation issue where the AttrListImpl
 could be deallocated before the global LLVMContext, causing memory errors. 
 Patch by Peter Collingbourne.

llvm-svn: 119721
---
 llvm/lib/VMCore/Attributes.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/VMCore/Attributes.cpp b/llvm/lib/VMCore/Attributes.cpp
index 477111a3ae8b..e4a228b8c62c 100644
--- a/llvm/lib/VMCore/Attributes.cpp
+++ b/llvm/lib/VMCore/Attributes.cpp
@@ -106,6 +106,11 @@ Attributes Attribute::typeIncompatible(const Type *Ty) {
 // AttributeListImpl Definition
 //===----------------------------------------------------------------------===//
 
+namespace llvm {
+  class AttributeListImpl;
+}
+
+static ManagedStatic<FoldingSet<AttributeListImpl> > AttributesLists;
 
 namespace llvm {
 static ManagedStatic<sys::SmartMutex<true> > ALMutex;
@@ -131,6 +136,8 @@ public:
   }
   void DropRef() {
     sys::SmartScopedLock<true> Lock(*ALMutex);
+    if (!AttributesLists.isConstructed())
+      return;
     sys::cas_flag new_val = --RefCount;
     if (new_val == 0)
       delete this;
@@ -147,8 +154,6 @@ public:
 };
 }
 
-static ManagedStatic<FoldingSet<AttributeListImpl> > AttributesLists;
-
 AttributeListImpl::~AttributeListImpl() {
   // NOTE: Lock must be acquired by caller.
   AttributesLists->RemoveNode(this);