Avoid redefinition of _bit_scan_{forward,reverse} macros

Fixes VcDevel#247.
amadio · Mar 6, 2020 · cc1daf3 · cc1daf3
1 parent 6808742
commit cc1daf3
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/Vc/common/bitscanintrinsics.h b/Vc/common/bitscanintrinsics.h
@@ -32,7 +32,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #  if Vc_GCC >= 0x40500
      // GCC 4.5.0 introduced _bit_scan_forward / _bit_scan_reverse
 #    include <x86intrin.h>
-#  else
+#  elif !defined(_bit_scan_forward)
      // GCC <= 4.4 and clang have x86intrin.h, but not the required functions
 #    define _bit_scan_forward(x) __builtin_ctz(x)
 #include "macros.h"