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x86/bitops: Introduce variable/constant pairs for __{set,clear,change}_bit()
Just as with test_bit, the non-atomic set/clear/change helpers can be better optimised by the compiler in the case that the nr parameter is constant, and it often is. This results in a general replacement of `mov $imm, %reg; bt* %reg, mem` with the shorter and more simple `op $imm, mem`, also reducing register pressure. The net diffstat is: add/remove: 0/1 grow/shrink: 5/17 up/down: 90/-301 (-211) As a piece of minor cleanup, drop unnecessary brackets in the test_bit() macro, and fix the indentation. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Dario Faggioli <dfaggioli@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com>
This commit is contained in:
Andrew Cooper committed
1 parent
418ae6021d
commit
2b84016c59
1 file changed
+27
-9
@@ -51,13 +51,19 @@ static inline void set_bit(int nr, volatile void *addr)
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* If it's called on the same region of memory simultaneously, the effect
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* may be that only one operation succeeds.
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*/
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static inline void __set_bit(int nr, void *addr)
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static inline void variable_set_bit(int nr, void *addr)
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{
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asm volatile ( "btsl %1,%0" : "+m" (*(int *)addr) : "Ir" (nr) : "memory" );
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}
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static inline void constant_set_bit(int nr, void *addr)
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{
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((unsigned int *)addr)[nr >> 5] |= (1u << (nr & 31));
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}
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#define __set_bit(nr, addr) ({ \
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if ( bitop_bad_size(addr) ) __bitop_bad_size(); \
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__set_bit(nr, addr); \
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__builtin_constant_p(nr) ? \
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constant_set_bit(nr, addr) : \
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variable_set_bit(nr, addr); \
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})
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/**
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@@ -86,13 +92,19 @@ static inline void clear_bit(int nr, volatile void *addr)
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* If it's called on the same region of memory simultaneously, the effect
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* may be that only one operation succeeds.
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*/
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static inline void __clear_bit(int nr, void *addr)
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static inline void variable_clear_bit(int nr, void *addr)
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{
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asm volatile ( "btrl %1,%0" : "+m" (*(int *)addr) : "Ir" (nr) : "memory" );
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}
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static inline void constant_clear_bit(int nr, void *addr)
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{
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((unsigned int *)addr)[nr >> 5] &= ~(1u << (nr & 31));
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}
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#define __clear_bit(nr, addr) ({ \
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if ( bitop_bad_size(addr) ) __bitop_bad_size(); \
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__clear_bit(nr, addr); \
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__builtin_constant_p(nr) ? \
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constant_clear_bit(nr, addr) : \
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variable_clear_bit(nr, addr); \
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})
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/**
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@@ -104,13 +116,19 @@ static inline void __clear_bit(int nr, void *addr)
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* If it's called on the same region of memory simultaneously, the effect
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* may be that only one operation succeeds.
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*/
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static inline void __change_bit(int nr, void *addr)
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static inline void variable_change_bit(int nr, void *addr)
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{
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asm volatile ( "btcl %1,%0" : "+m" (*(int *)addr) : "Ir" (nr) : "memory" );
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}
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static inline void constant_change_bit(int nr, void *addr)
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{
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((unsigned int *)addr)[nr >> 5] ^= (1u << (nr & 31));
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}
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#define __change_bit(nr, addr) ({ \
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if ( bitop_bad_size(addr) ) __bitop_bad_size(); \
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__change_bit(nr, addr); \
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__builtin_constant_p(nr) ? \
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constant_change_bit(nr, addr) : \
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variable_change_bit(nr, addr); \
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})
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/**
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@@ -291,9 +309,9 @@ static inline int variable_test_bit(int nr, const volatile void *addr)
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#define test_bit(nr, addr) ({ \
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if ( bitop_bad_size(addr) ) __bitop_bad_size(); \
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(__builtin_constant_p(nr) ? \
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constant_test_bit((nr),(addr)) : \
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variable_test_bit((nr),(addr))); \
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__builtin_constant_p(nr) ? \
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constant_test_bit(nr, addr) : \
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variable_test_bit(nr, addr); \
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})
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extern unsigned int __find_first_bit(
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