Commit b2bc1b1a authored by Heiko Carstens's avatar Heiko Carstens Committed by Alexander Gordeev
Browse files

s390/bitops: Provide optimized arch_test_bit() 



Provide an optimized arch_test_bit() implementation which makes use of
flag output constraint. This generates slightly better code:

bloat-o-meter:
add/remove: 51/19 grow/shrink: 450/2444 up/down: 25198/-49136 (-23938)

Acked-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
parent 8cae8e0a

arch/s390/include/asm/bitops.h

+33 −1
Original line number Diff line number Diff line
@@ -36,8 +36,40 @@ 
#include <linux/typecheck.h>

#include <linux/compiler.h>

#include <linux/types.h>

#include <asm/asm.h>



#define arch___set_bit			generic___set_bit

#define arch___clear_bit		generic___clear_bit

#define arch___change_bit		generic___change_bit

#define arch___test_and_set_bit		generic___test_and_set_bit

#define arch___test_and_clear_bit	generic___test_and_clear_bit

#define arch___test_and_change_bit	generic___test_and_change_bit

#define arch_test_bit_acquire		generic_test_bit_acquire



static __always_inline bool arch_test_bit(unsigned long nr, const volatile unsigned long *ptr)

{

#ifdef __HAVE_ASM_FLAG_OUTPUTS__

	const volatile unsigned char *addr;

	unsigned long mask;

	int cc;



	if (__builtin_constant_p(nr)) {

		addr = (const volatile unsigned char *)ptr;

		addr += (nr ^ (BITS_PER_LONG - BITS_PER_BYTE)) / BITS_PER_BYTE;

		mask = 1UL << (nr & (BITS_PER_BYTE - 1));

		asm volatile(

			"	tm	%[addr],%[mask]\n"

			: "=@cc" (cc)

			: [addr] "R" (*addr), [mask] "I" (mask)

			);

		return cc == 3;

	}

#endif

	return generic_test_bit(nr, ptr);

}



#include <asm-generic/bitops/atomic.h>

#include <asm-generic/bitops/non-atomic.h>

#include <asm-generic/bitops/non-instrumented-non-atomic.h>

#include <asm-generic/bitops/lock.h>



/*