All of lore.kernel.org
 help / color / mirror / Atom feed
From: Yury Norov <yury.norov@gmail.com>
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 <yury.norov@gmail.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>, Arnd Bergmann <arnd@arndb.de>,
	Dennis Zhou <dennis@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	David Sterba <dsterba@suse.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Stefano Brivio <sbrivio@redhat.com>,
	"Ma, Jianpeng" <jianpeng.ma@intel.com>,
	Wei Yang <richard.weiyang@linux.alibaba.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Subject: [PATCH 2/5] bits_per_long.h: introduce SMALL_CONST() macro
Date: Fri, 29 Jan 2021 12:45:25 -0800	[thread overview]
Message-ID: <20210129204528.2118168-4-yury.norov@gmail.com> (raw)
In-Reply-To: <20210129204528.2118168-1-yury.norov@gmail.com>

Many algorithms become simplier if they are passed with relatively small
input values. One example is bitmap operations when the whole bitmap fits
into one word. To implement such simplifications, linux/bitmap.h declares
small_const_nbits() macro.

Other subsystems may also benefit from optimizations of this sort, like
find_bit API in the following patches. So it looks helpful to generalize
the macro and extend it's visibility.

It should probably go to linux/kernel.h, but doing that creates circular
dependencies. So put it in asm-generic/bitsperlong.h.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/asm-generic/bitsperlong.h       |  2 ++
 include/linux/bitmap.h                  | 33 +++++++++++--------------
 include/linux/bits.h                    |  2 +-
 tools/include/asm-generic/bitsperlong.h |  2 ++
 tools/include/linux/bitmap.h            | 19 ++++++--------
 5 files changed, 28 insertions(+), 30 deletions(-)

diff --git a/include/asm-generic/bitsperlong.h b/include/asm-generic/bitsperlong.h
index 3905c1c93dc2..0eeb77544f1d 100644
--- a/include/asm-generic/bitsperlong.h
+++ b/include/asm-generic/bitsperlong.h
@@ -23,4 +23,6 @@
 #define BITS_PER_LONG_LONG 64
 #endif
 
+#define SMALL_CONST(n) (__builtin_constant_p(n) && (unsigned long)(n) < BITS_PER_LONG)
+
 #endif /* __ASM_GENERIC_BITS_PER_LONG */
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index c862082b4d1a..89e43ba775d4 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -224,9 +224,6 @@ extern int bitmap_print_to_pagebuf(bool list, char *buf,
  * so make such users (should any ever turn up) call the out-of-line
  * versions.
  */
-#define small_const_nbits(nbits) \
-	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
-
 static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
 {
 	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
@@ -278,7 +275,7 @@ extern void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
 static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return (*dst = *src1 & *src2 & BITS_FIRST_MASK(nbits - 1)) != 0;
 	return __bitmap_and(dst, src1, src2, nbits);
 }
@@ -286,7 +283,7 @@ static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = *src1 | *src2;
 	else
 		__bitmap_or(dst, src1, src2, nbits);
@@ -295,7 +292,7 @@ static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
 static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = *src1 ^ *src2;
 	else
 		__bitmap_xor(dst, src1, src2, nbits);
@@ -304,7 +301,7 @@ static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
 static inline int bitmap_andnot(unsigned long *dst, const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return (*dst = *src1 & ~(*src2) & BITS_FIRST_MASK(nbits - 1)) != 0;
 	return __bitmap_andnot(dst, src1, src2, nbits);
 }
@@ -312,7 +309,7 @@ static inline int bitmap_andnot(unsigned long *dst, const unsigned long *src1,
 static inline void bitmap_complement(unsigned long *dst, const unsigned long *src,
 			unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = ~(*src);
 	else
 		__bitmap_complement(dst, src, nbits);
@@ -328,7 +325,7 @@ static inline void bitmap_complement(unsigned long *dst, const unsigned long *sr
 static inline int bitmap_equal(const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return !((*src1 ^ *src2) & BITS_FIRST_MASK(nbits - 1));
 	if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 	    IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
@@ -350,7 +347,7 @@ static inline bool bitmap_or_equal(const unsigned long *src1,
 				   const unsigned long *src3,
 				   unsigned int nbits)
 {
-	if (!small_const_nbits(nbits))
+	if (!SMALL_CONST(nbits - 1))
 		return __bitmap_or_equal(src1, src2, src3, nbits);
 
 	return !(((*src1 | *src2) ^ *src3) & BITS_FIRST_MASK(nbits - 1));
@@ -359,7 +356,7 @@ static inline bool bitmap_or_equal(const unsigned long *src1,
 static inline int bitmap_intersects(const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return ((*src1 & *src2) & BITS_FIRST_MASK(nbits - 1)) != 0;
 	else
 		return __bitmap_intersects(src1, src2, nbits);
@@ -368,7 +365,7 @@ static inline int bitmap_intersects(const unsigned long *src1,
 static inline int bitmap_subset(const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return ! ((*src1 & ~(*src2)) & BITS_FIRST_MASK(nbits - 1));
 	else
 		return __bitmap_subset(src1, src2, nbits);
@@ -376,7 +373,7 @@ static inline int bitmap_subset(const unsigned long *src1,
 
 static inline bool bitmap_empty(const unsigned long *src, unsigned nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return ! (*src & BITS_FIRST_MASK(nbits - 1));
 
 	return find_first_bit(src, nbits) == nbits;
@@ -384,7 +381,7 @@ static inline bool bitmap_empty(const unsigned long *src, unsigned nbits)
 
 static inline bool bitmap_full(const unsigned long *src, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return ! (~(*src) & BITS_FIRST_MASK(nbits - 1));
 
 	return find_first_zero_bit(src, nbits) == nbits;
@@ -392,7 +389,7 @@ static inline bool bitmap_full(const unsigned long *src, unsigned int nbits)
 
 static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return hweight_long(*src & BITS_FIRST_MASK(nbits - 1));
 	return __bitmap_weight(src, nbits);
 }
@@ -428,7 +425,7 @@ static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
 static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 				unsigned int shift, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = (*src & BITS_FIRST_MASK(nbits - 1)) >> shift;
 	else
 		__bitmap_shift_right(dst, src, shift, nbits);
@@ -437,7 +434,7 @@ static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *s
 static inline void bitmap_shift_left(unsigned long *dst, const unsigned long *src,
 				unsigned int shift, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = (*src << shift) & BITS_FIRST_MASK(nbits - 1);
 	else
 		__bitmap_shift_left(dst, src, shift, nbits);
@@ -449,7 +446,7 @@ static inline void bitmap_replace(unsigned long *dst,
 				  const unsigned long *mask,
 				  unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = (*old & ~(*mask)) | (*new & *mask);
 	else
 		__bitmap_replace(dst, old, new, mask, nbits);
diff --git a/include/linux/bits.h b/include/linux/bits.h
index 3a29b1190744..e07e4a55241b 100644
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -37,7 +37,7 @@
 #define GENMASK(h, l) \
 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
 
-#define BITS_FIRST(nr)		GENMASK(nr), 0)
+#define BITS_FIRST(nr)		GENMASK((nr), 0)
 #define BITS_LAST(nr)		GENMASK(BITS_PER_LONG - 1, (nr))
 
 #define BITS_FIRST_MASK(nr)	__GENMASK((nr) % BITS_PER_LONG, 0)
diff --git a/tools/include/asm-generic/bitsperlong.h b/tools/include/asm-generic/bitsperlong.h
index 8f2283052333..432d272baf27 100644
--- a/tools/include/asm-generic/bitsperlong.h
+++ b/tools/include/asm-generic/bitsperlong.h
@@ -18,4 +18,6 @@
 #define BITS_PER_LONG_LONG 64
 #endif
 
+#define SMALL_CONST(n) (__builtin_constant_p(n) && (unsigned long)(n) < BITS_PER_LONG)
+
 #endif /* __ASM_GENERIC_BITS_PER_LONG */
diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
index ded716902bd0..bcbe6fe8fdab 100644
--- a/tools/include/linux/bitmap.h
+++ b/tools/include/linux/bitmap.h
@@ -19,12 +19,9 @@ int __bitmap_equal(const unsigned long *bitmap1,
 		   const unsigned long *bitmap2, unsigned int bits);
 void bitmap_clear(unsigned long *map, unsigned int start, int len);
 
-#define small_const_nbits(nbits) \
-	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG)
-
 static inline void bitmap_zero(unsigned long *dst, int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = 0UL;
 	else {
 		int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
@@ -35,7 +32,7 @@ static inline void bitmap_zero(unsigned long *dst, int nbits)
 static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
 {
 	unsigned int nlongs = BITS_TO_LONGS(nbits);
-	if (!small_const_nbits(nbits)) {
+	if (!SMALL_CONST(nbits - 1)) {
 		unsigned int len = (nlongs - 1) * sizeof(unsigned long);
 		memset(dst, 0xff,  len);
 	}
@@ -44,7 +41,7 @@ static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
 
 static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return ! (*src & BITS_FIRST_MASK(nbits - 1));
 
 	return find_first_bit(src, nbits) == nbits;
@@ -52,7 +49,7 @@ static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
 
 static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return ! (~(*src) & BITS_FIRST_MASK(nbits - 1));
 
 	return find_first_zero_bit(src, nbits) == nbits;
@@ -60,7 +57,7 @@ static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
 
 static inline int bitmap_weight(const unsigned long *src, int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return hweight_long(*src & BITS_FIRST_MASK(nbits - 1));
 	return __bitmap_weight(src, nbits);
 }
@@ -68,7 +65,7 @@ static inline int bitmap_weight(const unsigned long *src, int nbits)
 static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
 			     const unsigned long *src2, int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		*dst = *src1 | *src2;
 	else
 		__bitmap_or(dst, src1, src2, nbits);
@@ -146,7 +143,7 @@ size_t bitmap_scnprintf(unsigned long *bitmap, int nbits,
 static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 			     const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return (*dst = *src1 & *src2 & BITS_FIRST_MASK(nbits - 1)) != 0;
 	return __bitmap_and(dst, src1, src2, nbits);
 }
@@ -162,7 +159,7 @@ static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 static inline int bitmap_equal(const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
+	if (SMALL_CONST(nbits - 1))
 		return !((*src1 ^ *src2) & BITS_FIRST_MASK(nbits - 1));
 	if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
 	    IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
-- 
2.25.1


  parent reply	other threads:[~2021-01-29 20:48 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-29 20:45 [PATCH 0/6] lib/find_bit: fast path for small bitmaps Yury Norov
2021-01-29 20:45 ` [PATCH 1/6] arch: rearrange headers inclusion order in asm/bitops for m68k and sh Yury Norov
2021-01-29 20:45 ` [PATCH 2/6] lib: inttroduce BITS_{FIRST,LAST}() macro Yury Norov
2021-01-29 20:45 ` Yury Norov [this message]
2021-01-29 21:10   ` [PATCH 2/5] bits_per_long.h: introduce SMALL_CONST() macro Andy Shevchenko
2021-01-29 21:24     ` Joe Perches
2021-01-29 21:28     ` Yury Norov
2021-01-29 22:25     ` Yury Norov
2021-01-29 20:45 ` [PATCH 3/5] lib: inline _find_next_bit() wrappers Yury Norov
2021-01-29 20:45 ` [PATCH 4/5] lib: add fast path for find_next_*_bit() Yury Norov
2021-01-29 20:45 ` [PATCH 6/6] lib: add fast path for find_first_*_bit() and find_last_bit() Yury Norov
2021-01-29 20:51 ` [PATCH 0/6] lib/find_bit: fast path for small bitmaps Yury Norov
2021-01-29 21:12   ` Andy Shevchenko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210129204528.2118168-4-yury.norov@gmail.com \
    --to=yury.norov@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=andriy.shevchenko@linux.intel.com \
    --cc=arnd@arndb.de \
    --cc=dalias@libc.org \
    --cc=dennis@kernel.org \
    --cc=dsterba@suse.com \
    --cc=geert@linux-m68k.org \
    --cc=glaubitz@physik.fu-berlin.de \
    --cc=jianpeng.ma@intel.com \
    --cc=jpoimboe@redhat.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-m68k@lists.linux-m68k.org \
    --cc=linux-sh@vger.kernel.org \
    --cc=richard.weiyang@linux.alibaba.com \
    --cc=sbrivio@redhat.com \
    --cc=wsa+renesas@sang-engineering.com \
    --cc=ysato@users.sourceforge.jp \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.