Commit 437a0a54 authored Jun 20, 2008 by Ingo Molnar

x86, bitops: make constant-bit set/clear_bit ops faster, gcc workaround



Jeremy Fitzhardinge reported this compiler bug:

Suggestion from Linus: add "r" to the input constraint of the
set_bit()/clear_bit()'s constant 'nr' branch:

Blows up on "gcc version 3.4.4 20050314 (prerelease) (Debian 3.4.3-13)":

 CC      init/main.o
include2/asm/bitops.h: In function `start_kernel':
include2/asm/bitops.h:59: warning: asm operand 1 probably doesn't match constraints
include2/asm/bitops.h:59: warning: asm operand 1 probably doesn't match constraints
include2/asm/bitops.h:59: warning: asm operand 1 probably doesn't match constraints
include2/asm/bitops.h:59: error: impossible constraint in `asm'
include2/asm/bitops.h:59: error: impossible constraint in `asm'
include2/asm/bitops.h:59: error: impossible constraint in `asm'

Reported-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 7dbceaf9

include/asm-x86/bitops.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -58,7 +58,7 @@ static inline void set_bit(unsigned int nr, volatile unsigned long *addr)
		if (IS_IMMEDIATE(nr)) {
		asm volatile(LOCK_PREFIX "orb %1,%0"
		: CONST_MASK_ADDR(nr, addr)
		: "i" (CONST_MASK(nr))
		: "iq" ((u8)CONST_MASK(nr))
		: "memory");
		} else {
		asm volatile(LOCK_PREFIX "bts %1,%0"
		@@ -95,7 +95,7 @@ static inline void clear_bit(int nr, volatile unsigned long *addr)
		if (IS_IMMEDIATE(nr)) {
		asm volatile(LOCK_PREFIX "andb %1,%0"
		: CONST_MASK_ADDR(nr, addr)
		: "i" (~CONST_MASK(nr)));
		: "iq" ((u8)~CONST_MASK(nr)));
		} else {
		asm volatile(LOCK_PREFIX "btr %1,%0"
		: BITOP_ADDR(addr)

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