vppinfra: use count_trailing_zeros in sparse_vec_index

It is much cheaper to use ctzll than to do shift,subtract and mask
in likely case when we are looking for 1st set bit in the uword.

Change-Id: I31954081571978878c7098bafad0c85a91755fa2
Signed-off-by: Damjan Marion <damarion@cisco.com>

2 files changed, 7 insertions, 7 deletions

diff --git a/src/vnet/devices/virtio/vhost-user.c b/src/vnet/devices/virtio/vhost-user.c
index c1fca441fa5..7e10a60f5fb 100644
--- a/src/vnet/devices/virtio/vhost-user.c
+++ b/src/vnet/devices/virtio/vhost-user.c
@@ -248,8 +248,8 @@ map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
   r = _mm_blend_epi16 (r, _mm_and_si128 (rl, rh), 0x88);
 
   r = _mm_shuffle_epi8 (r, _mm_set_epi64x (0, 0x0e060c040a020800));
-  i = __builtin_ctzll (_mm_movemask_epi8 (r) |
-		       (1 << VHOST_MEMORY_MAX_NREGIONS));
+  i = count_trailing_zeros (_mm_movemask_epi8 (r) |
+			    (1 << VHOST_MEMORY_MAX_NREGIONS));
 
   if (i < vui->nregions)
     {
@@ -275,7 +275,7 @@ map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
 
   if (u32)
     {
-      i = __builtin_ctzll (u32);
+      i = count_trailing_zeros (u32);
       goto vhost_map_guest_mem_done;
     }
 
@@ -290,7 +290,7 @@ map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
 
   if (u32)
     {
-      i = __builtin_ctzll (u32);
+      i = count_trailing_zeros (u32);
       goto vhost_map_guest_mem_done;
     }
 
@@ -305,7 +305,7 @@ map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
 
   if (u32)
     {
-      i = __builtin_ctzll (u32);
+      i = count_trailing_zeros (u32);
       goto vhost_map_guest_mem_done;
     }
 
@@ -318,7 +318,7 @@ map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
   u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1) << 6);
   u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 7);
 
-  i = __builtin_ctzll (u32 | (1 << VHOST_MEMORY_MAX_NREGIONS));
+  i = count_trailing_zeros (u32 | (1 << VHOST_MEMORY_MAX_NREGIONS));
 
 vhost_map_guest_mem_done:
   if (i < vui->nregions)
diff --git a/src/vnet/l2/feat_bitmap.h b/src/vnet/l2/feat_bitmap.h
index 5940ff7ea9b..a1b295ac4ac 100644
--- a/src/vnet/l2/feat_bitmap.h
+++ b/src/vnet/l2/feat_bitmap.h
@@ -80,7 +80,7 @@ feat_bitmap_get_next_node_index (u32 * next_nodes, u32 bitmap)
 {
   u32 first_bit;
 
-  count_leading_zeros (first_bit, bitmap);
+  first_bit = count_leading_zeros (bitmap);
   first_bit = uword_bits - 1 - first_bit;
   return next_nodes[first_bit];
 }