Date: Thu, 27 Dec 2012 12:10:19 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Peter Wemm <peter@wemm.org> Cc: "arch@freebsd.org" <arch@freebsd.org>, Adrian Chadd <adrian@freebsd.org>, Alfred Perlstein <bright@mu.org>, Rui Paulo <rpaulo@freebsd.org>, Alfred Perlstein <alfred@ixsystems.com> Subject: Re: UPDATE Re: making use of userland dtrace on FreeBSD Message-ID: <50DC2C9B.4030802@FreeBSD.org> In-Reply-To: <CAGE5yCrnoNhOh3VaYU3bO6BwA=bpxD5QzkZvD%2BHaUwvXNQ%2BUfw@mail.gmail.com> References: <50D49DFF.3060803@ixsystems.com> <50DBC7E2.1070505@mu.org> <CAGE5yCq46NFKKzSUZq=jz0NwEnWdjPTK_0fpZ%2BwWV9FA0BSQCg@mail.gmail.com> <50DBD193.7080505@mu.org> <CAGE5yCrnoNhOh3VaYU3bO6BwA=bpxD5QzkZvD%2BHaUwvXNQ%2BUfw@mail.gmail.com>
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On 2012-12-27 06:32, Peter Wemm wrote: > On Wed, Dec 26, 2012 at 8:41 PM, Alfred Perlstein <bright@mu.org> wrote: ... >> Can you clarify some? If it was somewhat easy to re-add >> -fomit-frame-pointer to critical libraries like this, then that would be OK? > > No, you can't add MD flags like this. The way to do it is see things > like PIC, WARNS, etc where you can do overrides of defaults on a > directory basis, and respect the system-wide user overrides. > > Remember, -fno-omit-frame-pointer is the default on i386 (except at > high -O levels with gcc, I dont know where clang, the default > compiler, draws the line). Other platforms don't even have frame > pointers. You can't just scatter that switch around the place. Just for reference: - gcc versions < 4.6 always use -fno-omit-frame-pointer for i386, and enable -fomit-frame-pointer for amd64, when optimization is enabled (-O1 or higher). - gcc versions >= 4.6 enable -fomit-frame-pointer for both i386 and amd64, when optimization is enabled (-O1 or higher). - clang enables -fomit-frame-pointer only when explicity specified. I will submit a patch to upstream to make it mimic the behaviour of our gcc in base, e.g. enable -fomit-frame-pointer only for amd64, when optimization is enabled (-O1 or higher).
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