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Re: [C++ patch] Enable constructor decloning by default
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: Richard Biener <richard dot guenther at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Jason Merrill <jason at redhat dot com>
- Date: Mon, 19 May 2014 16:48:30 +0200
- Subject: Re: [C++ patch] Enable constructor decloning by default
- Authentication-results: sourceware.org; auth=none
- References: <20140518193231 dot GE1828 at kam dot mff dot cuni dot cz> <CAFiYyc1b7dVHQNauqZrAo1wBhcFgYK8FBwmDBFOdWMQ=tG_iDg at mail dot gmail dot com> <20140519144502 dot GC12624 at atrey dot karlin dot mff dot cuni dot cz>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Mon, May 19, 2014 at 04:45:02PM +0200, Jan Hubicka wrote:
> > On Sun, May 18, 2014 at 9:32 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> > > Hi,
> > > this patch enables -fdeclone-ctor-dtor by default: I believe it is up to the
> > > optimizers to decide when the actual worker body should be inlined into the
> > > thunks.
> > >
> > > Bootstrapped/regtested x86_64-linux, OK?
> >
> > Please make sure to not enable it for -O0 and -Og at least.
>
> Hmm, I tought this thunk can be implemented without clobbering debug info -
> all we need is to arrange it to be abstract and not show in unwind info...
I agree with Richard, you don't want to do this for -O0/-Og.
I don't think debuggers can filter functions from unwind info (they can do
that for inlines, but when it is not inlined...), and it will be a terrible
debugging experience if you see extra frame in there.
Jakub