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Re: Enale -fno-fat-lto-objects by default

On 2013.11.19 at 09:44 +0100, Paolo Bonzini wrote:
> 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:
> >> >
> >> > 
> >> > 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
> > and, 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.

OK, but where is upstream?
Please note that a general libtool update would fix this issue, too.
So, maybe it is just time to upgrade libtool everywhere in gnu-land?

> Patch 3 in the series is wrong because 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.

The problem is that fixincl links with libiberty.a:

/var/tmp/gcc_build_dir/./gcc/xgcc -B/var/tmp/gcc_build_dir/./gcc/
-B/usr/x86_64-pc-linux-gnu/bin/ -B/usr/x86_64-pc-linux-gnu/lib/ -isystem
/usr/x86_64-pc-linux-gnu/include -isystem
/usr/x86_64-pc-linux-gnu/sys-include    -O2 -pipe -static-libstdc++
-static-libgcc  -o fixincl fixincl.o fixtests.o fixfixes.o server.o
procopen.o fixlib.o fixopts.o ../libiberty/libiberty.a

And this archive consists of object files with LTO sections only. So we
need to find a way to pass -fuse-linker-plugin to the invocation above.


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