? constant_test_bit((nr), (addr)) \
: variable_test_bit((nr), (addr)))
+#if (defined(CONFIG_X86_GENERIC) || defined(CONFIG_GENERIC_CPU)) \
+ && !defined(CONFIG_CC_OPTIMIZE_FOR_SIZE)
+/*
+ * Since BSF and TZCNT have sufficiently similar semantics for the purposes
+ * for which we use them here, BMI-capable hardware will decode the prefixed
+ * variant as 'tzcnt ...' and may execute that faster than 'bsf ...', while
+ * older hardware will ignore the REP prefix and decode it as 'bsf ...'.
+ */
+# define BSF_PREFIX "rep;"
+#else
+# define BSF_PREFIX
+#endif
+
/**
* __ffs - find first set bit in word
* @word: The word to search
*/
static inline unsigned long __ffs(unsigned long word)
{
- asm("bsf %1,%0"
+ asm(BSF_PREFIX "bsf %1,%0"
: "=r" (word)
: "rm" (word));
return word;
*/
static inline unsigned long ffz(unsigned long word)
{
- asm("bsf %1,%0"
+ asm(BSF_PREFIX "bsf %1,%0"
: "=r" (word)
: "r" (~word));
return word;
}
+#undef BSF_PREFIX
+
/*
* __fls: find last set bit in word
* @word: The word to search