+ __asm _emit 0x0f __asm _emit 0x01 __asm _emit 0xd0 /*xgetbv*/
+ }
+}
+
+#else
+
+static uint64_t
+_xgetbv (uint32_t xcr)
+{
+#ifdef __APPLE__
+ /* it would be nice to make this work on OS X but as long we use veclib,
+ we don't really need to know about SSE/AVX on that platform.
+ */
+ return 0;
+#else
+ uint32_t eax, edx;
+ __asm__ volatile ("xgetbv" : "=a" (eax), "=d" (edx) : "c" (xcr));
+ return (static_cast<uint64_t>(edx) << 32) | eax;
+#endif