[libcxx] r297532 - Fix DoNotOptimize on MSVC

[Eric Fiselier via cfe-commits]

Author: ericwf
Date: Fri Mar 10 18:07:08 2017
New Revision: 297532

URL: http://llvm.org/viewvc/llvm-project?rev=297532&view=rev
Log:
Fix DoNotOptimize on MSVC

Modified:
    libcxx/trunk/test/support/test_macros.h

Modified: libcxx/trunk/test/support/test_macros.h
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/support/test_macros.h?rev=297532&r1=297531&r2=297532&view=diff
==============================================================================
--- libcxx/trunk/test/support/test_macros.h (original)
+++ libcxx/trunk/test/support/test_macros.h Fri Mar 10 18:07:08 2017
@@ -188,9 +188,11 @@ inline void DoNotOptimize(Tp const& valu
   asm volatile("" : : "g"(value) : "memory");
 }
 #else
+#include <intrin.h>
 template <class Tp>
-inline void DoNotOptimize(Tp const&) {
-  // FIXME: Do something here...
+inline void DoNotOptimize(Tp const& value) {
+  const volatile void* volatile = __builtin_addressof(value);
+  _ReadWriteBarrier();
 }
 #endif