Date: Mon, 04 Mar 2013 10:16:00 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Matt Burke <mattblists@icritical.com>, Andriy Gapon <avg@FreeBSD.org> Cc: freebsd-hackers@FreeBSD.org Subject: Re: clang generated code sometimes confuses fbt Message-ID: <51346650.90200@FreeBSD.org> In-Reply-To: <513453D4.4010305@icritical.com> References: <5132387E.8010808@FreeBSD.org> <513453D4.4010305@icritical.com>
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On 2013-03-04 08:57, Matt Burke wrote: > On 03/02/13 17:35, Andriy Gapon wrote: >> To summarize: I would be glad of either clang generated code was >> "fbt-friendly" or if ctf information was generated for >> bpobj_iterate_impl. Either is perfect for me. > > Apologies if this is a silly suggestion, but are you building with -O0? > I've noticed backtraces being hard to follow (i.e. skipping intermediate > and wrapper functions) with a kernel built with the default optimisation > level, and it seems to me that the same thing may be happening here - the > wrappers are being optimised out. No, the wrappers (bpobj_iterate and bpobj_iterate_nofree) are externally visible functions, so they cannot be optimized out. Both of them call bpobj_iterate_impl, which is a static function, e.g. a candidate for automatic inlining. However, bpobj_iterate_impl is quite big, and called from 3 different locations, so it does not actually get inlined, even with -O2.
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