lib/bitmap.c: micro-optimization for __bitmap_complement()

Use BITS_TO_LONGS() macro to avoid calculation of reminder (bits %
BITS_PER_LONG) On ARM64 it saves 5 instruction for function - 16 before
and 11 after.

Link: http://lkml.kernel.org/r/20180411145914.6011-1-ynorov@caviumnetworks.com
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/bitmap.c b/lib/bitmap.c
index a42eff7e8c48bd81dd3db841a1e04f1672980b91..58f9750e49c6867d7e26ab00ef28c62966168461 100644 (file)
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -64,12 +64,9 @@ EXPORT_SYMBOL(__bitmap_equal);
 
 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
 {
-       unsigned int k, lim = bits/BITS_PER_LONG;
+       unsigned int k, lim = BITS_TO_LONGS(bits);
        for (k = 0; k < lim; ++k)
                dst[k] = ~src[k];
-
-       if (bits % BITS_PER_LONG)
-               dst[k] = ~src[k];
 }
 EXPORT_SYMBOL(__bitmap_complement);