Date: Wed, 5 Sep 2012 10:36:50 +0100 From: David Chisnall <theraven@FreeBSD.org> To: Dimitry Andric <dimitry@andric.com> Cc: Garrett Cooper <yanegomi@gmail.com>, freebsd-current@FreeBSD.org, Steve Kargl <sgk@troutmask.apl.washington.edu> Subject: Re: Compiler performance tests on FreeBSD 10.0-CURRENT Message-ID: <96BD00DE-865C-4690-A2F1-E5B7C5D221C0@FreeBSD.org> In-Reply-To: <50471BEE.6030708@andric.com> References: <5046670C.6050500@andric.com> <20120904214344.GA17723@troutmask.apl.washington.edu> <504679CB.90204@andric.com> <20120904221413.GA19395@troutmask.apl.washington.edu> <CAGH67wTQavfh9ExsjypnCjw4yrV2RpdUUjxAD2kaZy-PiDocHA@mail.gmail.com> <50471BEE.6030708@andric.com>
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On 5 Sep 2012, at 10:31, Dimitry Andric wrote: > These are just the default FreeBSD optimization flags for building > clang, which are probably used by the majority of users out there. > This is the case that I was interested in particularly. The > -fno-strict-aliasing is not really my choice, but it was introduced > in the past by Nathan Whitehorn, who apparently saw problems without > it. It will hopefully disappear in the future. Clang currently defaults to no strict aliasing on FreeBSD. In my = experience, most C programmers misunderstand the aliasing rules of C and = even people on the C++ standards committee often get them wrong for C++, = so trading a 1-10% performance increase for a significant chance of = generating non-working code seems like a poor gain. If people are = certain that they do understand the rules, then they can add = -fstrict-aliasing to their own CFLAGS. David=
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