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[96.27.162.190]) by smtp.gmail.com with ESMTPSA id c127sm4331155qkd.87.2021.01.29.12.45.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Jan 2021 12:45:37 -0800 (PST) From: Yury Norov To: linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org, linux-arch@vger.kernel.org Cc: Yury Norov , Geert Uytterhoeven , Yoshinori Sato , Rich Felker , Arnd Bergmann , Dennis Zhou , Andrew Morton , Wolfram Sang , David Sterba , Andy Shevchenko , Stefano Brivio , "Ma, Jianpeng" , Wei Yang , Josh Poimboeuf , John Paul Adrian Glaubitz Subject: [PATCH 4/5] lib: add fast path for find_next_*_bit() Date: Fri, 29 Jan 2021 12:45:27 -0800 Message-Id: <20210129204528.2118168-6-yury.norov@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210129204528.2118168-1-yury.norov@gmail.com> References: <20210129204528.2118168-1-yury.norov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Similarly to bitmap functions, find_next_*_bit() users will benefit if we'll handle a case of bitmaps that fit into a single word. In the very best case, the compiler may replace a function call with a single ffs or ffz instruction. Signed-off-by: Yury Norov --- include/asm-generic/bitops/find.h | 30 +++++++++++++++++++++++++ include/asm-generic/bitops/le.h | 21 +++++++++++++++++ tools/include/asm-generic/bitops/find.h | 30 +++++++++++++++++++++++++ 3 files changed, 81 insertions(+) diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h index 7ad70dab8e93..8bd7a33a889d 100644 --- a/include/asm-generic/bitops/find.h +++ b/include/asm-generic/bitops/find.h @@ -20,6 +20,16 @@ static inline unsigned long find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size - 1)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr & GENMASK(size - 1, offset); + return val ? __ffs(val) : size; + } + return _find_next_bit(addr, NULL, size, offset, 0UL, 0); } #endif @@ -40,6 +50,16 @@ unsigned long find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size - 1)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr1 & *addr2 & GENMASK(size - 1, offset); + return val ? __ffs(val) : size; + } + return _find_next_bit(addr1, addr2, size, offset, 0UL, 0); } #endif @@ -58,6 +78,16 @@ static inline unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size - 1)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr | ~GENMASK(size - 1, offset); + return val == ~0UL ? size : ffz(val); + } + return _find_next_bit(addr, NULL, size, offset, ~0UL, 0); } #endif diff --git a/include/asm-generic/bitops/le.h b/include/asm-generic/bitops/le.h index 21305f6cea0b..18ebcf639d7f 100644 --- a/include/asm-generic/bitops/le.h +++ b/include/asm-generic/bitops/le.h @@ -5,6 +5,7 @@ #include #include #include +#include #if defined(__LITTLE_ENDIAN) @@ -37,6 +38,16 @@ static inline unsigned long find_next_zero_bit_le(const void *addr, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size)) { + unsigned long val = *(const unsigned long *)addr; + + if (unlikely(offset >= size)) + return size; + + val = swab(val) | ~GENMASK(size - 1, offset); + return val == ~0UL ? size : ffz(val); + } + return _find_next_bit(addr, NULL, size, offset, ~0UL, 1); } #endif @@ -46,6 +57,16 @@ static inline unsigned long find_next_bit_le(const void *addr, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size)) { + unsigned long val = *(const unsigned long *)addr; + + if (unlikely(offset >= size)) + return size; + + val = swab(val) & GENMASK(size - 1, offset); + return val ? __ffs(val) : size; + } + return _find_next_bit(addr, NULL, size, offset, 0UL, 1); } #endif diff --git a/tools/include/asm-generic/bitops/find.h b/tools/include/asm-generic/bitops/find.h index 9fe62d10b084..eff868bd22f8 100644 --- a/tools/include/asm-generic/bitops/find.h +++ b/tools/include/asm-generic/bitops/find.h @@ -20,6 +20,16 @@ static inline unsigned long find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size - 1)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr & GENMASK(size - 1, offset); + return val ? __ffs(val) : size; + } + return _find_next_bit(addr, NULL, size, offset, 0UL, 0); } #endif @@ -40,6 +50,16 @@ unsigned long find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size - 1)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr1 & *addr2 & GENMASK(size - 1, offset); + return val ? __ffs(val) : size; + } + return _find_next_bit(addr1, addr2, size, offset, 0UL, 0); } #endif @@ -58,6 +78,16 @@ static inline unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { + if (SMALL_CONST(size - 1)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr | ~GENMASK(size - 1, offset); + return val == ~0UL ? size : ffz(val); + } + return _find_next_bit(addr, NULL, size, offset, ~0UL, 0); } #endif -- 2.25.1