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Re: Enale -fno-fat-lto-objects by default
- From: Paolo Bonzini <bonzini at gnu dot org>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: Markus Trippelsdorf <markus at trippelsdorf dot de>, gcc-patches at gcc dot gnu dot org, dj at redhat dot com
- Date: Tue, 19 Nov 2013 09:44:05 +0100
- Subject: Re: Enale -fno-fat-lto-objects by default
- Authentication-results: sourceware.org; auth=none
- References: <20131118180458 dot GH11338 at kam dot mff dot cuni dot cz> <20131118184331 dot GA10148 at x4> <20131118190940 dot GA26530 at kam dot mff dot cuni dot cz>
Il 18/11/2013 20:09, Jan Hubicka ha scritto:
>>> > > this patch switches the default for fat-lto-objects as was documented for a while.
>>> > > -ffat-lto-objects doubles compilation time and often makes users to not notice that
>>> > > LTO was not used at all (because they forgot to use gcc-ar/gcc-nm plugins).
>>> > >
>>> > > Sadly I had to add -ffat-lto-objects to bootstrap. This is because I do not know
>>> > > how to convince our build machinery to use gcc-ar/gcc-nm during the stage2+
>> >
>> > I've posted a minimal patch set for slim-lto-bootstrap last year, see:
>> > http://thread.gmane.org/gmane.comp.gcc.patches/270842
>> >
>> > If there's interest I could repost it.
> It would be really nice to have it in indeed. I think we do not really need
> lto-bootstrap.mk and slim-lto-bootstrap.mk, but otherwise the patch seems easy
> enough and would save quite some of lto bootstrap testing time...
Patches 1 and 2 should go upstream first.
Patch 3 in the series is wrong because Makefile.in is a generated file.
The message does not explain why it is necessary, and it is probably
working around a bug elsewhere.
For patch 4, I agree with Jan that we do not need a separate configuration.
Paolo