Re: [patch 14/44] generic hweight{64,32,16,8}()

Akinobu Mita
2006-02-02T12:50:07Z

On Wed, Feb 01, 2006 at 11:24:27AM +0100, Andi Kleen wrote:
> On Wednesday 01 February 2006 10:26, Michael Tokarev wrote:
> > Andi Kleen wrote:
> > > On Wednesday 01 February 2006 10:02, Akinobu Mita wrote:
> > >
> > >>+static inline unsigned int hweight32(unsigned int w)
> > []
> > > How large are these functions on x86? Maybe it would be better to not inline them,
> > > but put it into some C file out of line.
> >
> > hweight8 47 bytes
> > hweight16 76 bytes
> > hweight32 97 bytes
> > hweight64 56 bytes (NOT inlining hweight32)
> > hweight64 197 bytes (inlining hweight32)
> >
> > Those are when compiled as separate non-inlined functions,
> > with pushl %ebp and ret.
>
> This would argue for moving them out of line.

This patch will put hweight*() into lib/hweight.c

Index: 2.6-git/include/asm-generic/bitops/hweight.h
=================================--- 2.6-git.orig/include/asm-generic/bitops/hweight.h
+++ 2.6-git/include/asm-generic/bitops/hweight.h
@@ -1,54 +1,9 @@
#ifndef _ASM_GENERIC_BITOPS_HWEIGHT_H_
#define _ASM_GENERIC_BITOPS_HWEIGHT_H_

-#include <asm/types.h>
-
-/**
- * hweightN - returns the hamming weight of a N-bit word
- * @x: the word to weigh
- *
- * The Hamming Weight of a number is the total number of bits set in it.
- */
-
-static inline unsigned int hweight32(unsigned int w)
-{
- unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
- res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
- res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
- res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
- return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
-}
-
-static inline unsigned int hweight16(unsigned int w)
-{
- unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
- res = (res & 0x3333) + ((res >> 2) & 0x3333);
- res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
- return (res & 0x00FF) + ((res >> 8) & 0x00FF);
-}
-
-static inline unsigned int hweight8(unsigned int w)
-{
- unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
- res = (res & 0x33) + ((res >> 2) & 0x33);
- return (res & 0x0F) + ((res >> 4) & 0x0F);
-}
-
-static inline unsigned long hweight64(__u64 w)
-{
-#if BITS_PER_LONG = 32
- return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
-#elif BITS_PER_LONG = 64
- u64 res;
- res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul);
- res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
- res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful);
- res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul);
- res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul);
- return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul);
-#else
-#error BITS_PER_LONG not defined
-#endif
-}
+extern unsigned int hweight32(unsigned int w);
+extern unsigned int hweight16(unsigned int w);
+extern unsigned int hweight8(unsigned int w);
+extern unsigned long hweight64(__u64 w);

#endif /* _ASM_GENERIC_BITOPS_HWEIGHT_H_ */
Index: 2.6-git/lib/Makefile
=================================--- 2.6-git.orig/lib/Makefile
+++ 2.6-git/lib/Makefile
@@ -5,7 +5,7 @@
lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \
idr.o div64.o int_sqrt.o bitmap.o extable.o prio_tree.o \
- sha1.o
+ sha1.o hweight.o

lib-y += kobject.o kref.o kobject_uevent.o klist.o

Index: 2.6-git/lib/hweight.c
=================================--- /dev/null
+++ 2.6-git/lib/hweight.c
@@ -0,0 +1,54 @@
+#include <linux/module.h>
+#include <asm/types.h>
+
+/**
+ * hweightN - returns the hamming weight of a N-bit word
+ * @x: the word to weigh
+ *
+ * The Hamming Weight of a number is the total number of bits set in it.
+ */
+
+unsigned int hweight32(unsigned int w)
+{
+ unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
+ res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
+ res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
+ res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
+ return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
+}
+EXPORT_SYMBOL(hweight32);
+
+unsigned int hweight16(unsigned int w)
+{
+ unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
+ res = (res & 0x3333) + ((res >> 2) & 0x3333);
+ res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
+ return (res & 0x00FF) + ((res >> 8) & 0x00FF);
+}
+EXPORT_SYMBOL(hweight16);
+
+unsigned int hweight8(unsigned int w)
+{
+ unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
+ res = (res & 0x33) + ((res >> 2) & 0x33);
+ return (res & 0x0F) + ((res >> 4) & 0x0F);
+}
+EXPORT_SYMBOL(hweight8);
+
+unsigned long hweight64(__u64 w)
+{
+#if BITS_PER_LONG = 32
+ return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
+#elif BITS_PER_LONG = 64
+ u64 res;
+ res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul);
+ res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
+ res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful);
+ res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul);
+ res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul);
+ return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul);
+#else
+#error BITS_PER_LONG not defined
+#endif
+}
+EXPORT_SYMBOL(hweight64);