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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2018-10-31 01:05:02 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-31 18:54:12 +0300
commitc8cebc553368209426f7279736db4f88f1853396 (patch)
tree9e7a7962d243563191df1080d0221e9e5a4d746a /include/linux/bitmap.h
parent7275b097851a5e2e0dd4da039c7e96b59ac5314e (diff)
downloadlinux-c8cebc553368209426f7279736db4f88f1853396.tar.xz
linux/bitmap.h: remove redundant uses of small_const_nbits()
In the _zero, _fill and _copy functions, the small_const_nbits branch is redundant. If nbits is small and const, gcc knows full well that BITS_TO_LONGS(nbits) is 1, so len is also a compile-time constant (sizeof(long)), and calling memset or memcpy with a length argument of sizeof(long) makes gcc generate the expected code anyway: #include <string.h> void a(unsigned long *x) { memset(x, 0, 8); } void b(unsigned long *x) { memset(x, 0xff, 8); } void c(unsigned long *x, const unsigned long *y) { memcpy(x, y, 8); } turns into 0000000000000000 <a>: 0: 48 c7 07 00 00 00 00 movq $0x0,(%rdi) 7: c3 retq 8: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1) f: 00 0000000000000010 <b>: 10: 48 c7 07 ff ff ff ff movq $0xffffffffffffffff,(%rdi) 17: c3 retq 18: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1) 1f: 00 0000000000000020 <c>: 20: 48 8b 06 mov (%rsi),%rax 23: 48 89 07 mov %rax,(%rdi) 26: c3 retq Link: http://lkml.kernel.org/r/20180818131623.8755-4-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Yury Norov <ynorov@caviumnetworks.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/bitmap.h')
-rw-r--r--include/linux/bitmap.h24
1 files changed, 6 insertions, 18 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index a9805bacbd7c..004cd42a3c4d 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -214,33 +214,21 @@ extern int bitmap_print_to_pagebuf(bool list, char *buf,
static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
{
- if (small_const_nbits(nbits))
- *dst = 0UL;
- else {
- unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
- memset(dst, 0, len);
- }
+ unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+ memset(dst, 0, len);
}
static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
{
- if (small_const_nbits(nbits))
- *dst = ~0UL;
- else {
- unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
- memset(dst, 0xff, len);
- }
+ unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+ memset(dst, 0xff, len);
}
static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
unsigned int nbits)
{
- if (small_const_nbits(nbits))
- *dst = *src;
- else {
- unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
- memcpy(dst, src, len);
- }
+ unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+ memcpy(dst, src, len);
}
/*