@@ -, +, @@ 
---
 src/sna/kgem.c |   17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)
--- a/src/sna/kgem.c	
+++ a/src/sna/kgem.c	
@@ -516,10 +516,19 @@ static void gem_close(int fd, uint32_t handle)
 
 constant inline static unsigned long __fls(unsigned long word)
 {
-	asm("bsr %1,%0"
-	    : "=r" (word)
-	    : "rm" (word));
-	return word;
+#if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 304)
+	return word == 0 ? 0 : 32 - __builtin_clz(word);
+#else
+	unsigned int v = 1;
+
+	if (word == 0)
+		return 0;
+
+	while (word >>= 1)
+		v++;
+
+	return v;
+#endif
 }
 
 constant inline static int cache_bucket(int num_pages)
--