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Date: Thu, 24 Sep 2009 21:26:00 -0000
From: Richard Guenther <rguenther@suse.de>
To: "Joseph S. Myers" <joseph@codesourcery.com>
Cc: gcc@gcc.gnu.org
Subject: Re: Prague GCC folks meeting summary report
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On Thu, 24 Sep 2009, Joseph S. Myers wrote:

> On Thu, 24 Sep 2009, Richard Guenther wrote:
> 
> > We discussed about features we don't like (PCH and -combine).  PCH
> > is used but has the issue that improper use is not diagnosed and PCH
> > seems to be unmaintained.  We agreed on deprecating -combine for 4.5
> > though.
> 
> Can we map -combine to use LTO transparently in 4.6 (deprecate the 
> implementation, keep the interface)?

We thought about that, but the issue with LTO is that you need to
use the gcc driver at link time and pass -flto there.  But yes,
in principle you could continue to handle -combine in the driver
by doing the link step to build an object file.  Supporting it
on cc1 is probably not going to work though.

Is -combine widely used?  IIRC it has a lot of known issues and
is basically unmaintained.  Maybe if we deprecate -combine for 4.5
we'll get feedback if it is used.

Richard.