-#ifndef exact_log2
-#define exact_log2(N) exact_log2_wide ((unsigned HOST_WIDE_INT) (N))
-#define floor_log2(N) floor_log2_wide ((unsigned HOST_WIDE_INT) (N))
-#endif
-extern int exact_log2_wide (unsigned HOST_WIDE_INT);
-extern int floor_log2_wide (unsigned HOST_WIDE_INT);
+/* Return floor of log2, with -1 for zero. */
+extern int floor_log2 (unsigned HOST_WIDE_INT);
+
+/* Inline versions of the above for speed. */
+#if GCC_VERSION >= 3004
+# if HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_LONG
+# define CLZ_HWI __builtin_clzl
+# define CTZ_HWI __builtin_ctzl
+# elif HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_LONGLONG
+# define CLZ_HWI __builtin_clzll
+# define CTZ_HWI __builtin_ctzll
+# else
+# define CLZ_HWI __builtin_clz
+# define CTZ_HWI __builtin_ctz
+# endif
+
+extern inline int
+floor_log2 (unsigned HOST_WIDE_INT x)
+{
+ return x ? HOST_BITS_PER_WIDE_INT - 1 - (int) CLZ_HWI (x) : -1;
+}
+
+extern inline int
+exact_log2 (unsigned HOST_WIDE_INT x)
+{
+ return x == (x & -x) && x ? (int) CTZ_HWI (x) : -1;
+}
+#endif /* GCC_VERSION >= 3004 */