lib: bitmap: eliminate branch in __bitmap_shift_left
We can shift the bits from lower and upper into place before assembling
dst[k + off]; moving the shift of lower into the branch where we already
know that rem is non-zero allows us to remove a conditional.
Signed-off-by: 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 74bdf360..36e380d 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -169,15 +169,14 @@
* word below and make them the bottom rem bits of result.
*/
if (rem && k > 0)
- lower = src[k - 1];
+ lower = src[k - 1] >> (BITS_PER_LONG - rem);
else
lower = 0;
upper = src[k];
if (left && k == lim - 1)
upper &= (1UL << left) - 1;
- dst[k + off] = upper << rem;
- if (rem)
- dst[k + off] |= lower >> (BITS_PER_LONG - rem);
+ upper <<= rem;
+ dst[k + off] = lower | upper;
if (left && k + off == lim - 1)
dst[k + off] &= (1UL << left) - 1;
}