Intrin.h: Implement _InterlockedExchangePointer

llvm-svn: 204827
diff --git a/clang/lib/Headers/Intrin.h b/clang/lib/Headers/Intrin.h
index 2ed8830..90a218e 100644
--- a/clang/lib/Headers/Intrin.h
+++ b/clang/lib/Headers/Intrin.h
@@ -422,6 +422,7 @@
 __int64 _InterlockedExchange64(__int64 volatile *_Target, __int64 _Value);
 static __inline__
 __int64 _InterlockedExchangeAdd64(__int64 volatile *_Addend, __int64 _Value);
+static __inline__
 void *_InterlockedExchangePointer(void *volatile *_Target, void *_Value);
 static __inline__
 __int64 _InterlockedIncrement64(__int64 volatile *_Addend);
@@ -795,6 +796,11 @@
   __atomic_exchange(_Target, &_Value, &_Value, 0);
   return _Value;
 }
+static __inline__ void *__attribute__((__always_inline__, __nodebug__))
+_InterlockedExchangePointer(void *volatile *_Target, void *_Value) {
+  __atomic_exchange(_Target, &_Value, &_Value, 0);
+  return _Value;
+}
 #endif
 /*----------------------------------------------------------------------------*\
 |* Interlocked Compare Exchange