From 82b58a843b9e7d61f8fcb91ddac41929a7f65b65 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Wed, 17 Jun 2009 00:28:49 +0000
Subject: [PATCH] Use atomic increment/decrement for reference counting of
 Type's.

llvm-svn: 73588
---
 llvm/include/llvm/System/Atomic.h | 4 ++--
 llvm/include/llvm/Type.h          | 8 +++++---
 llvm/lib/System/Atomic.cpp        | 4 ++--
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/llvm/include/llvm/System/Atomic.h b/llvm/include/llvm/System/Atomic.h
index f90a8f62e1c7..adbb975298e8 100644
--- a/llvm/include/llvm/System/Atomic.h
+++ b/llvm/include/llvm/System/Atomic.h
@@ -24,8 +24,8 @@ namespace llvm {
     cas_flag CompareAndSwap(volatile cas_flag* ptr,
                             cas_flag new_value,
                             cas_flag old_value);
-    cas_flag AtomicPostIncrement(volatile cas_flag* ptr);
-    cas_flag AtomicPostDecrement(volatile cas_flag* ptr);
+    cas_flag AtomicIncrement(volatile cas_flag* ptr);
+    cas_flag AtomicDecrement(volatile cas_flag* ptr);
   }
 }
 
diff --git a/llvm/include/llvm/Type.h b/llvm/include/llvm/Type.h
index 256944f60049..d439233d8c05 100644
--- a/llvm/include/llvm/Type.h
+++ b/llvm/include/llvm/Type.h
@@ -14,6 +14,7 @@
 #include "llvm/AbstractTypeUser.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/System/Atomic.h"
 #include "llvm/ADT/GraphTraits.h"
 #include "llvm/ADT/iterator.h"
 #include <string>
@@ -102,7 +103,7 @@ private:
   /// has no AbstractTypeUsers, the type is deleted.  This is only sensical for
   /// derived types.
   ///
-  mutable unsigned RefCount;
+  mutable sys::cas_flag RefCount;
 
   const Type *getForwardedTypeInternal() const;
 
@@ -337,7 +338,7 @@ public:
 
   void addRef() const {
     assert(isAbstract() && "Cannot add a reference to a non-abstract type!");
-    ++RefCount;
+    sys::AtomicIncrement(&RefCount);
   }
 
   void dropRef() const {
@@ -346,7 +347,8 @@ public:
 
     // If this is the last PATypeHolder using this object, and there are no
     // PATypeHandles using it, the type is dead, delete it now.
-    if (--RefCount == 0 && AbstractTypeUsers.empty())
+    sys::cas_flag OldCount = sys::AtomicDecrement(&RefCount);
+    if (OldCount == 0 && AbstractTypeUsers.empty())
       this->destroy();
   }
   
diff --git a/llvm/lib/System/Atomic.cpp b/llvm/lib/System/Atomic.cpp
index 9d8ac925b890..5676ca9d62c5 100644
--- a/llvm/lib/System/Atomic.cpp
+++ b/llvm/lib/System/Atomic.cpp
@@ -52,7 +52,7 @@ sys::cas_flag sys::CompareAndSwap(volatile sys::cas_flag* ptr,
 #endif
 }
 
-sys::cas_flag sys::AtomicPostIncrement(volatile sys::cas_flag* ptr) {
+sys::cas_flag sys::AtomicIncrement(volatile sys::cas_flag* ptr) {
 #if LLVM_MULTITHREADED==0
   ++(*ptr);
   return *ptr;
@@ -65,7 +65,7 @@ sys::cas_flag sys::AtomicPostIncrement(volatile sys::cas_flag* ptr) {
 #endif
 }
 
-sys::cas_flag sys::AtomicPostDecrement(volatile sys::cas_flag* ptr) {
+sys::cas_flag sys::AtomicDecrement(volatile sys::cas_flag* ptr) {
 #if LLVM_MULTITHREADED==0
   --(*ptr);
   return *ptr;