* Returns 0 if no bit is set, else returns the position of the most
* significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
*/
-#if defined(__i386) || defined(__x86_64)
+#if defined(URCU_ARCH_X86)
static inline
unsigned int fls_u32(uint32_t x)
{
#define HAS_FLS_U32
#endif
-#if defined(__x86_64)
+#if defined(URCU_ARCH_AMD64)
static inline
unsigned int fls_u64(uint64_t x)
{