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s390/bitops: Provide optimized arch_test_bit()

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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: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2024-12-13 13:27:34 +01:00 • committed by Alexander Gordeev
parent 8cae8e0afb
commit b2bc1b1a77
1 changed files with 33 additions and 1 deletions
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34
arch/s390/include/asm/bitops.h
View file

@ -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>
/*