Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail From: Gene Wirchenko Newsgroups: comp.lang.java.programmer,comp.lang.c Subject: Re: Arithmetic overflow checking Date: Tue, 12 Jul 2011 13:23:40 -0700 Organization: A noiseless patient Spider Lines: 22 Message-ID: <36bp17tf79bhbd6hovf9srhmcs1jh1c040@4ax.com> References: <9LWdnZH2hdfmyYvTnZ2dnUVZ_vidnZ2d@posted.palinacquisition> <3797038f-22d1-40b2-8c12-60db5a0976b8@t5g2000yqj.googlegroups.com> <4e1bf1bc$0$15671$4fafbaef@reader2.news.tin.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Info: mx04.eternal-september.org; posting-host="7Qrvczazr82YckO5XW8Vtw"; logging-data="5234"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/NDWvnzLJXthqIS9RsmuKHFvhy8mCBgrM=" X-Newsreader: Forte Agent 4.2/32.1118 Cancel-Lock: sha1:pyeq/EUWBl3cEos4vYkT2b72vjk= Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:6132 comp.lang.c:8190 On Tue, 12 Jul 2011 13:20:15 -0700, markspace <-@.> wrote: >On 7/12/2011 12:38 PM, Patricia Shanahan wrote: > >> It would not necessarily directly take time. It could be done in >> parallel with the stage that writes results back to register files, or >> bypasses them to other instructions. > > >A JO almost certainly would be executed in parallel with the ADD >instruction. Executing two instructions in parallel has been available >on consumer CPU (x86) since about 1992. It's two decade old technology. > Folks complaining about performance degradation due to overflow >detection are frankly greatly out of date in their understanding of CPU >architecture. I also suggest that they build a time machine and go for a ride on a certain Ariane 5 launch. Sincerely, Gene Wirchenko