From 838e8bb71dc0c892bf8f84abd3c709d8fe3a8d3c Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Fri, 24 Oct 2008 16:53:33 +0200 Subject: [PATCH] x86: Implement change_bit with immediate operand as "lock xorb" Impact: Minor optimization. Implement change_bit with immediate bit count as "lock xorb". This is similar to "lock orb" and "lock andb" for set_bit and clear_bit functions. Signed-off-by: Uros Bizjak Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/bitops.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 360010322711..9fa9dcdf344b 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -168,7 +168,15 @@ static inline void __change_bit(int nr, volatile unsigned long *addr) */ static inline void change_bit(int nr, volatile unsigned long *addr) { - asm volatile(LOCK_PREFIX "btc %1,%0" : ADDR : "Ir" (nr)); + if (IS_IMMEDIATE(nr)) { + asm volatile(LOCK_PREFIX "xorb %1,%0" + : CONST_MASK_ADDR(nr, addr) + : "iq" ((u8)CONST_MASK(nr))); + } else { + asm volatile(LOCK_PREFIX "btc %1,%0" + : BITOP_ADDR(addr) + : "Ir" (nr)); + } } /** -- GitLab