[PATCH 6/7] lib: bitmap: Eliminate branch in __bitmap_shift_left

[Rasmus Villemoes]

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@xxxxxxxxxxxxxxxxxx>
---
 lib/bitmap.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 5edd71b..2362601 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -167,15 +167,14 @@ void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
 		 * 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;
 	}
-- 
2.0.4

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