Date: Sun, 11 Jun 2017 14:25:17 +0200 From: Serpent7776 <serpent7776@gmail.com> To: Friedrich Locke <friedrich.locke@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: -O2 flag Message-ID: <20170611142517.5898c64e@DaemONX> In-Reply-To: <593C892D.4070200@gmail.com> References: <593C4679.5010104@gmail.com> <20170610230928.581e3cf9@DaemONX> <593C892D.4070200@gmail.com>
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On Sat, 10 Jun 2017 21:05:01 -0300 Friedrich Locke <friedrich.locke@gmail.com> wrote: > Here you have it: > > gustav# cc --version > FreeBSD clang version 3.8.0 (tags/RELEASE_380/final 262564) (based on > LLVM 3.8.0) > Target: x86_64-unknown-freebsd11.0 > Thread model: posix > InstalledDir: /usr/bin > gustav# This is not telling much. As pointed by Patrick this might be due to uninitialized stack variables in a function. You might want to try to: - rebuild with enabled compiler warning flags (-W flags) https://clang.llvm.org/docs/DiagnosticsReference.html - rebuild with sanitizer enabled https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html - try running in debugger and find place where this error occurs HTH > Em 10/06/2017 18:09, Serpent7776 escreveu: > > On Sat, 10 Jun 2017 16:20:25 -0300 > > Friedrich Locke <friedrich.locke@gmail.com> wrote: > > > >> Hi folks, > >> > >> i am trying compile a program with cc on freebsd 11. > >> When i use -O2 compilation flag, the compiled code is giving error on > >> execution, but with i omit -O2 everything works ok. > >> > >> Have anybody already faced such problem ? > > Yes, a few times in the past. Your code may have hidden bug which is > > triggered only with optimizations enabled. It might be relying on some kind > > of undefined behaviour. > > Unfortunately, I don't have any helpful advices on how to find this error - > > try enabling all compiler warnings flags. > > I'd suspect a bug in your code rather than a bug in compiler, but the > > latter is not impossible. > > > >> Thanks in advance. > >> _______________________________________________ > >> freebsd-questions@freebsd.org mailing list > >> https://lists.freebsd.org/mailman/listinfo/freebsd-questions > >> To unsubscribe, send any mail to > >> "freebsd-questions-unsubscribe@freebsd.org" > > > > > > -- /* * Serpent7776 */
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