From: Khem Raj <raj.khem@gmail.com>
To: buildroot@busybox.net
Subject: [Buildroot] build of gcc 4.3.5 broken with BR2_GCC_USE_SJLJ_EXCEPTIONS
Date: Sun, 1 Aug 2010 15:23:03 -0700 [thread overview]
Message-ID: <20100801222303.GC30928@gmail.com> (raw)
In-Reply-To: <20100727203043.74441c59@surf>
On (27/07/10 20:30), Thomas Petazzoni wrote:
> On Fri, 23 Jul 2010 00:05:22 +0200
> "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr> wrote:
>
> > Marcus, All,
> >
> > On Thursday 22 July 2010 23:59:25 Ossy wrote:
> > > I don't need this particular option (BR2_GCC_USE_SJLJ_EXCEPTIONS)
> > > but anyway my buildroot version (current git tree) wasn't able to
> > > build 4.3.5-final with BR2_GCC_USE_SJLJ_EXCEPTIONS=y. After
> > > deactivating it everything was fine again.
> >
> > Yes, it happens too for me with armeb. Other archs are fine for me
> > with sjlj enabled.
> >
> > I did not dig up why, so I /simply/ turn off sjlj for ermeb.
>
> Does having this BR2_GCC_USE_SJLJ_EXCEPTIONS option makes sense ? In
> which case would this be useful ?
It makes sense if you are using older compilers and when DWARF unwinding
did not work completely. But otherwise its slow in performance and probably
can be replaced with dwarf2 exceptions I think hpux is one which does not
support dwarf2 exception per gcc sources.
sjlj handles exceptions faster but also adds burden of calling setjmp in
non excepting case therefore slowing down the execution but code is
smaller.
I think you could leave this option in but dont make it default.
>
> According to http://choices.cs.uiuc.edu/exceptions.pdf, the default
> mechanism used by g++ for exceptions is faster and better than SJLJ.
>
> If there are only corner use cases, I'm all for getting rid of this
> option in BR. Advanced users can always use
> BR2_EXTRA_GCC_CONFIG_OPTIONS to add --enable-sjlj-exceptions to the gcc
> configuration if they want.
>
> Thoughts ?
>
> Thomas
> --
> Thomas Petazzoni, Free Electrons
> Kernel, drivers, real-time and embedded Linux
> development, consulting, training and support.
> http://free-electrons.com
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prev parent reply other threads:[~2010-08-01 22:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-22 21:59 [Buildroot] build of gcc 4.3.5 broken with BR2_GCC_USE_SJLJ_EXCEPTIONS Ossy
2010-07-22 22:05 ` Yann E. MORIN
2010-07-27 18:30 ` Thomas Petazzoni
2010-08-01 22:23 ` Khem Raj [this message]
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