Add a SmartScopedLock, and use it to simplify code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73722 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/System/Mutex.h

@@ -115,6 +115,22 @@ namespace llvm
     
     /// Mutex - A standard, always enforced mutex.
     typedef SmartMutex<false> Mutex;
+    
+    template<bool mt_only>
+    class SmartScopedLock  {
+      SmartMutex<mt_only>* mtx;
+      
+    public:
+      SmartScopedLock(SmartMutex<mt_only>* m) : mtx(m) {
+        mtx->acquire();
+      }
+      
+      ~SmartScopedLock() {
+        mtx->release();
+      }
+    };
+    
+    typedef SmartScopedLock<false> ScopedLock;
   }
 }