Build failure while experimenting with LTO

[Davide Italiano]

On Sun, Jun 26, 2016 at 6:48 PM, Davide Italiano <dccitaliano at gmail.com> wrote:
> Hi,
> I'm experimenting a bit with LTO using clang and lld (the new LLVM linker).
> I'm able to build a decent fraction of libreoffice if I invoke
> autogen.sh like this:
>
> ./autogen.sh CC=~/work/llvm/build-release/bin/clang
> CXX=~/work/llvm/build-release/bin/clang++
> AR=~/work/llvm/build-release/bin/llvm-ar RANLIB=/usr/bin/true
> LDFLAGS="-fuse-ld=lld" CFLAGS="-flto" CXXFLAGS="-flto" --without-java
> --without-help --without-myspell-dicts --disable-liblangtag
> --with-system-curl --with-system-lcms2
>
> (please note that as long as I'm using the LLVM tools I don't need
> plugin(s) as binutils does).
>
> I set up my PATH so that ld symlinks to lld.
>
> $ ld --version
> LLD 3.9 (https://llvm.org/svn/llvm-project/lld/trunk 273771)
>
> After some librabries/executables are built/linked successfully I hit
> the following:
>
> [build DEP] LNK:Library/libbiblo.so
> [build LNK] Library/libbiblo.so
> /home/davide/lto_experiments/libreoffice/external/coinmp/ExternalPackage_coinmp.mk:31:
> *** file /home/davide/lto_experiments/libreoffice/workdir/UnpackedTarball/coinmp/Cbc/src/.libs/libCbc.so.3.8.8
> does not exist in the tarball.  Stop.
> make[1]: *** Waiting for unfinished jobs....
> Makefile:254: recipe for target 'build' failed
> make: *** [build] Error 2
> ```
>
> $ find . -name "libCbc.so*"
> $
>
> So I decided to build libCbc by myself going in the correct directory
> and invoking make:
>
> $ cd ./workdir/UnpackedTarball/coinmp/Cbc/ && ./configure && make
> [...]
>
> but still the build fails with the same error.
> Any ideas why the library is not built? Is this a bug in LLVM or in
> the build system?
>
> As a side note, I'm able to finish successfully a non-LTO build with clang+lld.
>
> Thanks!
>
> --
> Davide

Also, FWIW this is the revision I'm at:

commit 63f15b36f7a196edb20ce7a0aba6f6b3d28dd652
Author: Ashod Nakashian <ashod.nakashian at collabora.co.uk>
Date:   Sun Jun 12 22:04:50 2016 -0400

--
Davide