linux-ext4 - [PATCH] lib/ext2fs: Use __builtin_popcount when available Signed-off-by: Cristian Rodríguez <crrodriguez@...nsuse.org>

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Message-Id: <1357484683-3021-1-git-send-email-crrodriguez@opensuse.org>
Date:	Sun,  6 Jan 2013 12:04:43 -0300
From:	Cristian Rodríguez <crrodriguez@...nsuse.org>
To:	linux-ext4@...r.kernel.org
Cc:	Cristian Rodríguez <crrodriguez@...nsuse.org>
Subject: [PATCH] lib/ext2fs: Use __builtin_popcount when available Signed-off-by: Cristian Rodríguez <crrodriguez@...nsuse.org>

---
 lib/ext2fs/bitops.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/ext2fs/bitops.c b/lib/ext2fs/bitops.c
index 7c3f215..0668469 100644
--- a/lib/ext2fs/bitops.c
+++ b/lib/ext2fs/bitops.c
@@ -125,11 +125,15 @@ static unsigned int popcount8(unsigned int w)
 
 static unsigned int popcount32(unsigned int w)
 {
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+	return __builtin_popcount(w);
+#else
 	unsigned int res = w - ((w >> 1) & 0x55555555);
 	res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
 	res = (res + (res >> 4)) & 0x0F0F0F0F;
 	res = res + (res >> 8);
 	return (res + (res >> 16)) & 0x000000FF;
+#endif
 }
 
 unsigned int ext2fs_bitcount(const void *addr, unsigned int nbytes)
-- 
1.8.1

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