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Date: Fri, 28 Nov 2014 17:01:09 +0100 From: Rasmus Villemoes <linux@...musvillemoes.dk> To: Andrew Morton <akpm@...ux-foundation.org>, Jan Kara <jack@...e.cz> Cc: linux-kernel@...r.kernel.org Subject: [PATCH 6/7] lib: bitmap: Eliminate branch in __bitmap_shift_left 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 <linux@...musvillemoes.dk> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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