From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752173AbaK1QC4 (ORCPT ); Fri, 28 Nov 2014 11:02:56 -0500 Received: from mail-lb0-f174.google.com ([209.85.217.174]:36715 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752067AbaK1QCD (ORCPT ); Fri, 28 Nov 2014 11:02:03 -0500 From: Rasmus Villemoes To: Andrew Morton , Jan Kara Cc: linux-kernel@vger.kernel.org Subject: [PATCH 6/7] lib: bitmap: Eliminate branch in __bitmap_shift_left Date: Fri, 28 Nov 2014 17:01:09 +0100 Message-Id: <1417190476-18066-7-git-send-email-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.0.4 In-Reply-To: <1417190476-18066-1-git-send-email-linux@rasmusvillemoes.dk> References: <1417190476-18066-1-git-send-email-linux@rasmusvillemoes.dk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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