From: Wu Fengguang <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Jamie Lokier <jamie@shareable.org>,
Roland Dreier <rdreier@cisco.com>,
Wu Fengguang <fengguang.wu@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: <linux-fsdevel@vger.kernel.org>
Subject: [PATCH 2/6] bitops: compile time optimization for hweight_long(CONSTANT)
Date: Fri, 15 Jan 2010 09:39:56 +0800 [thread overview]
Message-ID: <20100115014422.405089087@intel.com> (raw)
In-Reply-To: 20100115013954.311049665@intel.com
[-- Attachment #1: constant-hweight32.patch --]
[-- Type: text/plain, Size: 868 bytes --]
This allows use of hweight_long() in BUILD_BUG_ON().
Suggested by Jamie.
CC: Jamie Lokier <jamie@shareable.org>
CC: Roland Dreier <rdreier@cisco.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
include/linux/bitops.h | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
--- linux.orig/include/linux/bitops.h 2010-01-09 12:13:00.000000000 +0800
+++ linux/include/linux/bitops.h 2010-01-09 12:21:50.000000000 +0800
@@ -40,10 +40,14 @@ static __inline__ int get_count_order(un
return order;
}
-static inline unsigned long hweight_long(unsigned long w)
-{
- return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
-}
+#define hweight_long(x) \
+( \
+ __builtin_constant_p(x) ? \
+ __builtin_popcountl(x) : \
+ (sizeof(x) <= 4 ? \
+ hweight32(x) : \
+ hweight64(x)) \
+)
/**
* rol32 - rotate a 32-bit value left
next prev parent reply other threads:[~2010-01-15 1:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-15 1:39 [PATCH 0/6] FMODE_NONOTIFY, FMODE_RANDOM and FMODE_NEG_OFFSET bits Wu Fengguang
2010-01-15 1:39 ` [PATCH 1/6] fanotify: fix FMODE_NONOTIFY bit number Wu Fengguang
2010-01-15 1:39 ` Wu Fengguang [this message]
2010-01-15 1:39 ` [PATCH 3/6] vfs: O_* bit numbers uniqueness check Wu Fengguang
2010-01-15 1:39 ` [PATCH 4/6] vfs: take f_lock on modifying f_mode after open time Wu Fengguang
2010-01-15 1:39 ` [PATCH 5/6] readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM Wu Fengguang
2010-01-15 1:40 ` [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos Wu Fengguang
2010-01-16 12:54 ` OGAWA Hirofumi
2010-01-18 0:15 ` KAMEZAWA Hiroyuki
2010-01-18 1:17 ` OGAWA Hirofumi
2010-01-18 1:25 ` KAMEZAWA Hiroyuki
2010-01-18 1:38 ` OGAWA Hirofumi
2010-01-18 2:00 ` KAMEZAWA Hiroyuki
2010-01-18 2:13 ` OGAWA Hirofumi
2010-01-18 2:30 ` KAMEZAWA Hiroyuki
2010-01-18 3:15 ` Wu, Fengguang
2010-01-18 3:22 ` KAMEZAWA Hiroyuki
2010-01-18 5:26 ` Wu, Fengguang
2010-01-19 0:37 ` KAMEZAWA Hiroyuki
2010-01-18 1:32 ` OGAWA Hirofumi
2010-01-18 1:49 ` KAMEZAWA Hiroyuki
2010-01-18 1:59 ` OGAWA Hirofumi
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