From 739b7a90754924a0f023e8bb865d247ad0a60311 Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Sat, 21 Dec 2013 01:15:21 +0100 Subject: [PATCH] bitops: provide an inline implementation of find_first_bit find_first_bit has started to be used heavily in TCG code. The current implementation based on find_next_bit is not optimal and can't be optimized be the compiler if the bit array has a fixed size, which is the case most of the time. This new implementation does not use find_next_bit and is yet small enough to be inlined. Cc: Corentin Chary Reviewed-by: Richard Henderson Signed-off-by: Aurelien Jarno --- include/qemu/bitops.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h index 340b1e73bd..7e2d5c996e 100644 --- a/include/qemu/bitops.h +++ b/include/qemu/bitops.h @@ -157,7 +157,17 @@ unsigned long find_next_zero_bit(const unsigned long *addr, static inline unsigned long find_first_bit(const unsigned long *addr, unsigned long size) { - return find_next_bit(addr, size, 0); + unsigned long result, tmp; + + for (result = 0; result < size; result += BITS_PER_LONG) { + tmp = *addr++; + if (tmp) { + result += ctzl(tmp); + return result < size ? result : size; + } + } + /* Not found */ + return size; } /**