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>

1 files changed, 3 insertions, 4 deletions

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 74bdf3601245..36e380da00c5 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -169,15 +169,14 @@ 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;
         }