[PATCH 3/6] bitops: define gen_test_bit() the same way as the rest of functions

Alexander Lobakin
2022-06-06T11:50:43Z

Currently, the generic test_bit() function is defined as a one-liner
and in case with constant bitmaps the compiler is unable to optimize
it to a constant. At the same time, gen_test_and_*_bit() are being
optimized pretty good.
Define gen_test_bit() the same way as they are defined.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
---
include/asm-generic/bitops/generic-non-atomic.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/bitops/generic-non-atomic.h b/include/asm-generic/bitops/generic-non-atomic.h
index 7a60adfa6e7d..202d8a3b40e1 100644
--- a/include/asm-generic/bitops/generic-non-atomic.h
+++ b/include/asm-generic/bitops/generic-non-atomic.h
@@ -118,7 +118,11 @@ gen___test_and_change_bit(unsigned int nr, volatile unsigned long *addr)
static __always_inline int
gen_test_bit(unsigned int nr, const volatile unsigned long *addr)
{
- return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
+ const unsigned long *p = (const unsigned long *)addr + BIT_WORD(nr);
+ unsigned long mask = BIT_MASK(nr);
+ unsigned long val = *p;
+
+ return !!(val & mask);
}

#endif /* __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H */
--
2.36.1