Date: Tue, 6 Aug 2002 09:15:48 -0500 From: Dan Nelson <dnelson@allantgroup.com> To: Terry Lambert <tlambert2@mindspring.com> Cc: Darren Pilgrim <dmp@pantherdragon.org>, Jason Andresen <jandrese@mitre.org>, Dmitry Morozovsky <marck@rinet.ru>, hackers@FreeBSD.ORG Subject: Re: -fomit-frame-pointer for the world build Message-ID: <20020806141548.GB78723@dan.emsphone.com> In-Reply-To: <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> <3D4F751E.1A5C1327@mindspring.com>
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In the last episode (Aug 06), Terry Lambert said: > 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-). I thought the main thing you got out of -fomit-frame-pointer was a free register, which is a scarce commodity on x86. -- Dan Nelson dnelson@allantgroup.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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