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From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 3/7] lib: bitmap: Remove redundant code from __bitmap_shift_right
Date: Fri, 28 Nov 2014 17:01:06 +0100	[thread overview]
Message-ID: <1417190476-18066-4-git-send-email-linux@rasmusvillemoes.dk> (raw)
In-Reply-To: <1417190476-18066-1-git-send-email-linux@rasmusvillemoes.dk>

If the condition k==lim-1 is true, we must have off == 0 (otherwise, k
could never become that big). But in that case we have upper == 0 and
hence dst[k] == (src[k] & mask) >> rem. Since mask consists of a
consecutive range of bits starting from the LSB, anding dst[k] with
mask is a no-op.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/bitmap.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 9250c3f..20bb314 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -134,8 +134,6 @@ void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 			lower &= mask;
 		lower >>= rem;
 		dst[k] = lower | upper;
-		if (left && k == lim - 1)
-			dst[k] &= mask;
 	}
 	if (off)
 		memset(&dst[lim - off], 0, off*sizeof(unsigned long));
-- 
2.0.4


  parent reply	other threads:[~2014-11-28 16:01 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-28 16:01 [PATCH 0/7] lib: bitmap: Simplify bitmap_shift_{left,right} Rasmus Villemoes
2014-11-28 16:01 ` [PATCH 1/7] lib: bitmap: Change bitmap_shift_right to take unsigned parameters Rasmus Villemoes
2014-11-28 16:01 ` [PATCH 2/7] lib: bitmap: Eliminate branch in __bitmap_shift_right Rasmus Villemoes
2014-11-28 16:01 ` Rasmus Villemoes [this message]
2014-11-28 16:01 ` [PATCH 4/7] lib: bitmap: Yet another simplification " Rasmus Villemoes
2014-11-28 16:01 ` [PATCH 5/7] lib: bitmap: Change bitmap_shift_left to take unsigned parameters Rasmus Villemoes
2014-11-28 16:01 ` [PATCH 6/7] lib: bitmap: Eliminate branch in __bitmap_shift_left Rasmus Villemoes
2014-11-28 16:01 ` [PATCH 7/7] lib: bitmap: Remove redundant code from __bitmap_shift_left Rasmus Villemoes

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