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    SubjectRe: [PATCH 3/6] bitops: define gen_test_bit() the same way as the rest of functions
    On Mon, Jun 06, 2022 at 01:49:04PM +0200, Alexander Lobakin wrote:
    > 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>

    Regardless of whether compilers prefer this, I think it's nicer to have the
    structure consistent with the rest of the functions, so FWIW:

    Acked-by: Mark Rutland <mark.rutland@arm.com>

    Mark.

    > ---
    > 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
    >

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