lib: bitmap: eliminate branch in __bitmap_shift_right

We can shift the bits from lower and upper into place before assembling dst[k]; moving the shift of upper into the branch where we already know that rem is non-zero allows us to remove a conditional. Signed-off-by: Rasmus Villemoes <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
kyagi · Feb 14, 2015 · 9d8a6b2 · 9d8a6b2
1 parent 2fbad29
commit 9d8a6b2
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/lib/bitmap.c b/lib/bitmap.c
@@ -129,13 +129,13 @@ void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 			upper = src[off + k + 1];
 			if (off + k + 1 == lim - 1 && left)
 				upper &= mask;
+			upper <<= (BITS_PER_LONG - rem);
 		}
 		lower = src[off + k];
 		if (left && off + k == lim - 1)
 			lower &= mask;
-		dst[k] = lower >> rem;
-		if (rem)
-			dst[k] |= upper << (BITS_PER_LONG - rem);
+		lower >>= rem;
+		dst[k] = lower | upper;
 		if (left && k == lim - 1)
 			dst[k] &= mask;
 	}