vppinfra: use bzhi in pow2_mask when available

Saves one clock....

Type: improvement
Change-Id: I43da40fb4887b77ac851f759c50a7ca2814f8f40
Signed-off-by: Damjan Marion <damarion@cisco.com>

diff --git a/src/vppinfra/clib.h b/src/vppinfra/clib.h
index f0c3aca..81b59e2 100644 (file)
--- a/src/vppinfra/clib.h
+++ b/src/vppinfra/clib.h
@@ -251,6 +251,9 @@ min_log2_u64 (u64 x)
 always_inline uword
 pow2_mask (uword x)
 {
+#ifdef __BMI2__
+  return _bzhi_u64 (-1ULL, x);
+#endif
   return ((uword) 1 << x) - (uword) 1;
 }