+
+# if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64)
+
+/* While gcc falls back to its own generic code if the machine
+ on which it's running doesn't support popcount, with Microsoft's
+ compiler we need to detect and fallback ourselves. */
+# pragma intrinsic __cpuid
+# pragma intrinsic __popcnt
+# pragma intrinsic __popcnt64
+
+/* Return nonzero if popcount is supported. */
+
+/* 1 if supported, 0 if not supported, -1 if unknown. */
+extern int popcount_support;
+
+COUNT_ONE_BITS_INLINE int
+popcount_supported (void)
+{
+ if (popcount_support < 0)
+ {
+ int cpu_info[4];
+ __cpuid (cpu_info, 1);
+ popcount_support = (cpu_info[2] >> 23) & 1; /* See MSDN. */
+ }
+ return popcount_support;
+}
+
+# define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \
+ do \
+ { \
+ if (popcount_supported ()) \
+ return MSC_BUILTIN (x); \
+ else \
+ COUNT_ONE_BITS_GENERIC (TYPE); \
+ } \
+ while (0)
+# else
+# define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \
+ COUNT_ONE_BITS_GENERIC (TYPE)
+# endif