Index: sys/dev/cxgbe/osdep.h
===================================================================
--- sys/dev/cxgbe/osdep.h
+++ sys/dev/cxgbe/osdep.h
@@ -130,14 +130,6 @@
 #define PCI_EXP_LNKSTA_NLW	PCIEM_LINK_STA_WIDTH
 #define PCI_EXP_DEVCTL2		PCIER_DEVICE_CTL2
 
-static inline int
-ilog2(long x)
-{
-	KASSERT(x > 0 && powerof2(x), ("%s: invalid arg %ld", __func__, x));
-
-	return (flsl(x) - 1);
-}
-
 static inline char *
 strstrip(char *s)
 {
Index: sys/dev/mana/gdma_util.h
===================================================================
--- sys/dev/mana/gdma_util.h
+++ sys/dev/mana/gdma_util.h
@@ -170,15 +170,6 @@
 	return (max);
 }
 
-static inline unsigned long
-ilog2(unsigned long x)
-{
-	unsigned long log = x;
-	while (x >>= 1)
-		log++;
-	return (log);
-}
-
 static inline unsigned long
 roundup_pow_of_two(unsigned long x)
 {
Index: sys/powerpc/booke/pmap_64.c
===================================================================
--- sys/powerpc/booke/pmap_64.c
+++ sys/powerpc/booke/pmap_64.c
@@ -125,7 +125,6 @@
 #define	VM_MAPDEV_PA_MAX	0x4000000000000000 /* Don't encroach on DMAP */
 
 static void tid_flush(tlbtid_t tid);
-static unsigned long ilog2(unsigned long);
 
 /**************************************************************************/
 /* Page table management */
@@ -746,18 +745,6 @@
 /* TID handling */
 /**************************************************************************/
 
-/*
- * Return the largest uint value log such that 2^log <= num.
- */
-static unsigned long
-ilog2(unsigned long num)
-{
-	long lz;
-
-	__asm ("cntlzd %0, %1" : "=r" (lz) : "r" (num));
-	return (63 - lz);
-}
-
 /*
  * Invalidate all TLB0 entries which match the given TID. Note this is
  * dedicated for cases when invalidations should NOT be propagated to other
Index: sys/sys/libkern.h
===================================================================
--- sys/sys/libkern.h
+++ sys/sys/libkern.h
@@ -186,6 +186,31 @@
 	    8 * sizeof(mask) - __builtin_clzll((unsigned long long)mask));
 }
 
+static __inline __pure2 int
+ilog2(int mask)
+{
+
+	MPASS(mask != 0);
+	return (8 * sizeof(mask) - 1 - __builtin_clz((u_int)mask));
+}
+
+static __inline __pure2 int
+ilog2l(long mask)
+{
+
+	MPASS(mask != 0);
+	return (8 * sizeof(mask) - 1 - __builtin_clzl((u_long)mask));
+}
+
+static __inline __pure2 int
+ilog2ll(long long mask)
+{
+
+	MPASS(mask != 0);
+	return (8 * sizeof(mask) - 1 -
+	    __builtin_clzll((unsigned long long)mask));
+}
+
 #define	bitcount64(x)	__bitcount64((uint64_t)(x))
 #define	bitcount32(x)	__bitcount32((uint32_t)(x))
 #define	bitcount16(x)	__bitcount16((uint16_t)(x))