#if defined(__GNUC__) && \
(defined(__i386) || FOLLY_X64 || \
defined(ARCH_K8))
-#define RW_SPINLOCK_USE_X86_INTRINSIC_
-#include <x86intrin.h>
+# define RW_SPINLOCK_USE_X86_INTRINSIC_
+# include <x86intrin.h>
+#elif defined(_MSC_VER) && defined(FOLLY_X64)
+# define RW_SPINLOCK_USE_X86_INTRINSIC_
#else
-#undef RW_SPINLOCK_USE_X86_INTRINSIC_
+# undef RW_SPINLOCK_USE_X86_INTRINSIC_
#endif
// iOS doesn't define _mm_cvtsi64_si128 and friends
-#if defined(__SSE2__) && !TARGET_OS_IPHONE
+#if (FOLLY_SSE >= 2) && !TARGET_OS_IPHONE
#define RW_SPINLOCK_USE_SSE_INSTRUCTIONS_
#else
#undef RW_SPINLOCK_USE_SSE_INSTRUCTIONS_