Date: Tue, 06 Aug 2002 00:05:02 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Darren Pilgrim <dmp@pantherdragon.org> Cc: Jason Andresen <jandrese@mitre.org>, Dmitry Morozovsky <marck@rinet.ru>, hackers@freebsd.org Subject: Re: -fomit-frame-pointer for the world build Message-ID: <3D4F751E.1A5C1327@mindspring.com> References: <20020802212841.R58905-100000@woozle.rinet.ru> <3D4AC526.4CD399B3@mindspring.com> <3D4C8464.A2F4775A@pantherdragon.org> <3D4CC81F.94526C8A@mindspring.com> <3D4EA466.C1289F0F@mitre.org> <3D4EF091.EA1C91D3@pantherdragon.org> <3D4F0A5F.9B76573F@mindspring.com> <3D4F58B2.E58C2865@pantherdragon.org>
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Darren Pilgrim wrote: > > If you attamept to mix code that does callee pop or tail call > > optimization (e.g. in a library) with code that omits the > > frame pointer, or vice versa, then either the caller is going > > to push something that is never popped, or the callee is going > > to pop something that is never pushed. For hand coded assembly > > functions, it's not possible to make it obey the options which > > control this (e.g when it is not the caller which does both > > the pushing and popping of arguments). > > Are there any such known instances in the FreeBSD base code or any of > the (more popular) ports? I don't know. I don't think anyone has spent the effort on an audit, just so they could turn on an optimization that is only going to impact function call overhead, mostly in poorly written programs that have a high "calling functions vs. doing real work" ratio. 8-). So the answer is "use at your own risk" and the meta answer is "don't ask for it to be turned on by default unless you are willing to do a full audit of the code, thanks". -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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