From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:56446) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UFRTJ-00013s-3a for qemu-devel@nongnu.org; Tue, 12 Mar 2013 11:50:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UFRTB-0002aj-Lp for qemu-devel@nongnu.org; Tue, 12 Mar 2013 11:50:35 -0400 Received: from ssl.dlhnet.de ([91.198.192.8]:46020 helo=ssl.dlh.net) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UFRTB-0002ad-Fb for qemu-devel@nongnu.org; Tue, 12 Mar 2013 11:50:29 -0400 Message-ID: <513F4EC7.6010109@dlhnet.de> Date: Tue, 12 Mar 2013 16:50:31 +0100 From: Peter Lieven MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [RFC][PATCH 4/9] buffer_is_zero: use vector optimizations if possible List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "qemu-devel@nongnu.org" Cc: Kevin Wolf , Paolo Bonzini , Orit Wasserman , Stefan Hajnoczi performance gain on SSE2 is approx. 20-25%. altivec is not tested. performance for unsigned long arithmetic is unchanged. Signed-off-by: Peter Lieven --- util/cutils.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/util/cutils.c b/util/cutils.c index a09d8e8..23f0cd6 100644 --- a/util/cutils.c +++ b/util/cutils.c @@ -186,6 +186,11 @@ bool buffer_is_zero(const void *buf, size_t len) * latency. */ + if (((uintptr_t) buf) % sizeof(VECTYPE) == 0 + && len % 8*sizeof(VECTYPE) == 0) { + return buffer_find_nonzero_offset(buf, len)==len; + } + size_t i; long d0, d1, d2, d3; const long * const data = buf; -- 1.7.9.5