Date: Sat, 23 Dec 2006 01:52:20 +0100 From: Uwe Doering <gemini@geminix.org> To: Garrett Cooper <youshi10@u.washington.edu> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Properly controlling CFLAGS/CXXFLAGS Message-ID: <458C7DC4.1080304@geminix.org> In-Reply-To: <458C1BCB.6040907@u.washington.edu> References: <200612220850.kBM8oDD0037287@lurza.secnetix.de> <458C1BCB.6040907@u.washington.edu>
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Garrett Cooper wrote:
>> [...]
> Interesting. No wonder I didn't have it in my Gentoo /etc/make.conf. It
> appears (from what I see) that maybe -fno-strict-aliasing has been
> enabled by default (at least it doesn't show up in the GCC 4.1.1 manpage
> on FC5).
It's documented in GCC's info page. There, you may want to search for
'-fstrict-aliasing' instead of '-fno-strict-aliasing'. The 'no-' prefix
is generic and can be used to switch off flags that are on by default or
have been set to on earlier in the command line.
With '-O2' and better, '-fstrict-aliasing' is the default in newer
versions of GCC, AFAIK, but people tend to switch it off because it
apparently breaks too many software packages. Or at least those whose
code base dates back to times where '-fno-strict-aliasing' was the
default and people got away with certain nasty coding hacks that no
longer work with '-fstrict-aliasing'.
Uwe
--
Uwe Doering | EscapeBox - Managed On-Demand UNIX Servers
gemini@geminix.org | http://www.escapebox.net
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