Path: csiph.com!xmission!news.snarked.org!border2.nntp.dca1.giganews.com!nntp.giganews.com!news.iecc.com!.POSTED.news.iecc.com!nerds-end From: Gene Wirchenko Newsgroups: comp.compilers Subject: Re: Optimization techniques and runtime checks Date: Sat, 11 May 2019 22:43:29 -0700 Organization: A noiseless patient Spider Lines: 52 Sender: news@iecc.com Approved: comp.compilers@iecc.com Message-ID: <19-05-081@comp.compilers> References: <72d208c9-169f-155c-5e73-9ca74f78e390@gkc.org.uk> <19-04-021@comp.compilers> <19-04-023@comp.compilers> <19-04-037@comp.compilers> <19-04-046@comp.compilers> <19-05-052@comp.compilers> <19-05-059@comp.compilers> <19-05-064@comp.compilers> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="23709"; mail-complaints-to="abuse@iecc.com" Keywords: errors Posted-Date: 12 May 2019 12:41:13 EDT X-submission-address: compilers@iecc.com X-moderator-address: compilers-request@iecc.com X-FAQ-and-archives: http://compilers.iecc.com Xref: csiph.com comp.compilers:2316 On Wed, 8 May 2019 10:31:25 +0200, David Brown wrote: [snip] >And often there is no way to handle run-time errors sensibly anyway. Rule 1 of handling run-time errors sensibily: DD EEE TTT EEE CC TTT TTT H H EEE M M ! D D E T E C T T H H E MMM ! D D EE T EE C T T HHH EE M M ! D D E T E C T T H H E M M DD EEE T EEE CC T T H H EEE M M ! >You don't want your car brakes to give you a message "Your braking >system has encountered an integer overflow. Please report this error to >your car dealer". You want the brake software developers to be >/absolutely/ sure that overflows can't happen - and then there is no >point in run-time checks. I have read too many stories about "This should never happen." conditions happening. >Most probably no user will ever have a chance to report above error :-] Maybe not. Try a Web search -- I use duckduckgo.com myself -- for: honda brakes problem I do not know what the issue was. Ahem! I do not know what the issues were. Apparently, there was a problem in 2009 or so and just now. [snip] >Yes. I realise that this oddity is "for historical reasons". The same >applies to a great many oddities in C. "Those who do not know history are condemned to repeat it." Those who are stuck with unrevised standards are similarly condemned. [snip] Sincerely, Gene Wirchenko [This is defininitely far from compilers. The recent error is that a system that's supposed to brake to avoid collisions somtimes brakes at random in heavy traffic. Sounds like a bug but not one that could have been optimized away. -John]