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Re: Prague GCC folks meeting summary report
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.