From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey.Brodkin@synopsys.com (Alexey Brodkin) Date: Fri, 30 Oct 2015 15:54:02 +0000 Subject: [PATCH] __div64_32: implement division by multiplication for 32-bit arches In-Reply-To: References: <1446072455-16074-1-git-send-email-abrodkin@synopsys.com> List-ID: Message-ID: <1446220442.4394.42.camel@synopsys.com> To: linux-snps-arc@lists.infradead.org Hi Nicolas, On Fri, 2015-10-30@11:17 -0400, Nicolas Pitre wrote: > On Fri, 30 Oct 2015, M?ns Rullg?rd wrote: > > > Nicolas Pitre writes: > > > > > OK... I was intrigued, so I adapted my ARM code to the generic case, > > > including the overflow avoidance optimizations. Please have look and > > > tell me how this works for you. > > > > > > If this patch is accepted upstream, then it could be possible to > > > abstract only the actual multiplication part with some architecture > > > specific assembly. > > > > Good idea. > > Could you please provide a reviewed-by or acked-by tag? Sure! Acked-by: Alexey Brodkin BTW I thought about that optimization a bit more and now I think we may even skip addition of arch-specific assembly insertions. That's because that kind of division as discussed many times should be used as limited as possible, in other words there should be just a very few usages of it especially in very frequently used code paths. And in that case there might be not much of benefit having do_div() even faster and smaller than the one we're about to get with your change. -Alexey