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Re: libtool and LTO
From: |
Ralf Wildenhues |
Subject: |
Re: libtool and LTO |
Date: |
Tue, 5 Oct 2010 06:07:12 +0200 |
User-agent: |
Mutt/1.5.20 (2010-08-04) |
Hello Andi, Bob,
* Bob Friesenhahn wrote on Tue, Oct 05, 2010 at 12:30:51AM CEST:
> On Mon, 4 Oct 2010, Andi Kleen wrote:
>
> >I discovered that libtool breaks gcc LTO (link time optimization)
> >
> >Is there a solution or a workaround known?
> >
> >I'm using libtool 2.2.6b
>
> Maybe you should use libtool 2.4?
Yep, 2.4 should work with GCC LTO in every way *except* when partial
linking is involved in the process. The latter should generally only
happen when command line length limits are exceeded. We didn't try to
work around the 'ld -r' case because IIUC gold was going to be enhanced
to also support this OOTB (right?).
Getting Libtool 2.4 into GCC before 4.6 is on my list, by the way.
> [...] if you are using Automake I
> have heard that there are some fixes in development Automake which
> are needed/useful for -flto.
I'm not aware of fixes needed in Automake. Care to point them out?
Thanks,
Ralf