Commit 739b7a90 authored by Aurelien Jarno's avatar Aurelien Jarno
Browse files

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 <corentin.chary@gmail.com>
Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Signed-off-by: default avatarAurelien Jarno <aurelien@aurel32.net>
parent 2edaf21b

include/qemu/bitops.h

+11 −1
Original line number Diff line number Diff line
@@ -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;

}



/**