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Re: [PATCH][RFC] Add -Og
- From: Olivier Hainque <hainque at adacore dot com>
- To: Hans-Peter Nilsson <hp at bitrange dot com>
- Cc: Olivier Hainque <hainque at adacore dot com>, Eric Botcazou <ebotcazou at adacore dot com>, Richard Guenther <richard dot guenther at gmail dot com>, Richard Guenther <rguenther at suse dot de>, gcc-patches at gcc dot gnu dot org
- Date: Wed, 5 Sep 2012 10:43:27 +0200
- Subject: Re: [PATCH][RFC] Add -Og
- References: <alpine.LNX.2.00.1208101318510.28649@zhemvz.fhfr.qr> <CAFiYyc2wsRJVgLAxfegLpa02Tx5nmAprNp35hLrEEpJCKRBEUw@mail.gmail.com> <alpine.BSF.2.00.1209041630580.82722@dair.pair.com>
On Sep 4, 2012, at 22:42 , Hans-Peter Nilsson <hp@bitrange.com> wrote:
> Please, no inlining. Think of stack back-traces and their use
> when debugging.
> But, there was a talk at the GNU Tools
> Cauldron with related contents -
> <http://gcc.gnu.org/wiki/cauldron2012#Control-flow_preservation_in_GCC_for_safety-critical_uses>.
>
> It'll be Very Nice if control flow preservation was part of -Og
> or at least they played nice together.
A general comment first: I think the compromise Richard aims at
satisfying is a very useful one:
<< It aims at providing fast compilation, a superior debugging
experience and reasonable runtime performance.
>>
While there are commonalities with preserve-control-flow, indeed,
there are differences in target concerns as well.
We did a lot of work to support inlining for example :-)
Our experience is that compromises of this kind are extremely sensitive to
micro details spreadout in multiple places, so I'm afraid having one part of
the other might be hard.
Olivier