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Re: [PATCH][Ada] arm-linux sjlj port
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Mikael Pettersson <mikpe at it dot uu dot se>
- Cc: laurent at guerby dot net, aph at redhat dot com, Julian Brown <julian at codesourcery dot com>, Arnaud Charlet <charlet at adacore dot com>, gcc-patches at gcc dot gnu dot org, Matthias Klose <doko at debian dot org>, Martin Guy <martinwguy at gmail dot com>, Joel Sherrill <joel dot sherrill at oarcorp dot com>, Ludovic Brenta <ludovic at ludovic-brenta dot org>, Geert Bosch <bosch at adacore dot com>, Olivier Hainque <hainque at adacore dot com>, Eric Botcazou <ebotcazou at adacore dot com>
- Date: Mon, 07 Sep 2009 14:27:52 +0100
- Subject: Re: [PATCH][Ada] arm-linux sjlj port
- References: <4A82D295.4030907@oarcorp.com> <56d259a00908121407h19820522y850231afa937ed3a@mail.gmail.com> <4A832F30.3000708@debian.org> <19081.10792.105185.512212@pilspetsen.it.uu.se> <1250976793.17842.404.camel@localhost> <1251517614.5049.91.camel@localhost> <19097.768.413069.836610@pilspetsen.it.uu.se> <19099.37987.927752.847987@pilspetsen.it.uu.se> <1252319138.5049.1764.camel@localhost> <1252319604.17746.2.camel@e200601-lin.cambridge.arm.com> <1252320407.5049.1775.camel@localhost> <19108.61188.689111.806413@pilspetsen.it.uu.se> <1252326034.17746.13.camel@e200601-lin.cambridge.arm.com> <19109.2157.548820.296587@pilspetsen.it.uu.se>
On Mon, 2009-09-07 at 15:19 +0200, Mikael Pettersson wrote:
> Richard Earnshaw writes:
> >
> > On Mon, 2009-09-07 at 13:31 +0200, Mikael Pettersson wrote:
> > > So right now we have a choice of (a) no Ada for ARM EABI, or (b)
> > > an SJLJ Ada for ARM EABI. With (b) we at least have a working and
> > > testable system until someone can work out the ZCX EH details.
> >
> > But SJLJ is NOT compatible with the EABI.
>
> Right, it's not if we consider Ada code linked with EH-using
> code from other languages or binary code producers that do use
> ARM EABI EH. But pure Ada images linked with non-EH using C runtimes
> should work. And that's enough for the Ada compiler to sustain
> itself (remember that Ada requires Ada at bootstrap-time) while
> the limitations are being addressed.
>
> One can build gcc's Ada with ZCX support selected for ARM EABI,
> it just needs two small tweaks for compile-time issues. But the
> resulting Ada binaries die whenever an exception is raised;
> in particular, the Ada compiler itself uses exceptions in a
> bootstrap-time helper program (xsinfo, I have a reasonable fix
> for that one too). And much of the test suite fails as well.
>
> Would an ARM Ada port with a known broken ZCX EH implementation,
> but which is able to rebuild itself, be more acceptable?
I don't think either is acceptable. However, I'm concerned that this
short-term expediency will become a drag to long-term conformance.
Sometimes it's important to get these things right from the beginning or
the legacy will become impossible to eradicate.
R.