From: Uros Bizjak Date: Fri, 24 Oct 2008 14:53:33 +0000 (+0200) Subject: x86: Implement change_bit with immediate operand as "lock xorb" X-Git-Tag: v2.6.29-rc1~536^2~53 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=838e8bb71dc0c892bf8f84abd3c709d8fe3a8d3c;p=linux-2.6-omap-h63xx.git 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 --- diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 36001032271..9fa9dcdf344 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)); + } } /**