-combine option for C++ sources‏

-combine option for C++ sources‏

[Pramod Joisha]

Presently, the -combine option works only for C sources. I was wondering whether there are technical reasons for not supporting it for C++ sources. If not, are there plans for providing this support in the near future?

Pramod
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Re: -combine option for C++ sources‏

[Richard Guenther]

2009/5/5 Pramod Joisha <pramod_joisha@hotmail.com>:
>
>
> Presently, the -combine option works only for C sources. I was wondering whether there are technical reasons for not supporting it for C++ sources. If not, are there plans for providing this support in the near future?

As LTO will obsolete -combine I do not see that -combine will be
ever implemented for anything else besides C.

Richard.

Re: Re: -combine option for C++ sources‏

[Joseph S. Myers]

On Tue, 5 May 2009, Richard Guenther wrote:

> 2009/5/5 Pramod Joisha <pramod_joisha@hotmail.com>:
> >
> >
> > Presently, the -combine option works only for C sources. I was 
> > wondering whether there are technical reasons for not supporting it 
> > for C++ sources. If not, are there plans for providing this support in 
> > the near future?
> 
> As LTO will obsolete -combine I do not see that -combine will be
> ever implemented for anything else besides C.

Formally there are things -combine does that LTO doesn't 
(front-end-specific consistency checks across translation units, 
supporting non-ELF targets).  But I agree we should deprecate -combine 
when LTO goes in (or better, deprecate the mechanism it uses and make the 
driver transparently wrap LTO if possible); the consistency checks might 
better be done through plugins, and there should be no great difficulty in 
adding LTO support for non-ELF targets (that support arbitrary named 
sections) if desired.

(The C++ front end should still grow some sort of support for handling 
information from multiple translation units at once to implement exported 
templates, but that's another matter.)

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: -combine option for C++ sources‏

[Ian Lance Taylor]

Pramod Joisha <pramod_joisha@hotmail.com> writes:

> Presently, the -combine option works only for C sources. I was
> wondering whether there are technical reasons for not supporting it
> for C++ sources. If not, are there plans for providing this support in
> the near future?

As a historical note, Geoff Keating, who implemented -combine for C, was
working on -combine for C++ when his employer, Apple, decided to halt
contributions to gcc.  I don't know how far he got or whether he would
be able to share his patches.

Ian