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From:   Alexander Lobakin <alexandr.lobakin@intel.com>
To:     Arnd Bergmann <arnd@arndb.de>, Yury Norov <yury.norov@gmail.com>
Cc:     Alexander Lobakin <alexandr.lobakin@intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Richard Henderson <rth@twiddle.net>,
        Matt Turner <mattst88@gmail.com>,
        Brian Cain <bcain@quicinc.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
        "David S. Miller" <davem@davemloft.net>,
        Kees Cook <keescook@chromium.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
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        Tony Luck <tony.luck@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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Subject: [PATCH 3/6] bitops: define gen_test_bit() the same way as the rest of functions
Date:   Mon,  6 Jun 2022 13:49:04 +0200
Message-Id: <20220606114908.962562-4-alexandr.lobakin@intel.com>
In-Reply-To: <20220606114908.962562-1-alexandr.lobakin@intel.com>
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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