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Linux building with LTO 
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Joined: 2016-06-19 21:33:37
Posts: 337
Location: Columbus area, OH, USA
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Hi Henri,

I thought I would experiment with the --lto option for the build script, unfortunately, building with the flag is unsuccessful on my rig. I'm currently running Fedora 27 which includes using gcc 7.2.1 and cmake 3.10.1. Omitting the --lto flag produces a successful, executable build, as I have done many times (though I also include the --tune flag). I realize use of the new flag is experimental, as you noted in the changelog, so success might not be possible without significant investigation. I attached the capture of the build stdout/err which shows segfaults that might be to blame (though not much else of use). Abrt reports that:
Code:
/usr/bin/gcc-ar cr libcmake.a CMakeFiles/cmake.dir/cmake_dummy.cpp.o
triggered a (the first?) crash. I have included a file with some of the output from that as well.

Unfortunately, I'm a bit out of my depth. If there is a simple suggestion or two, I would pursue it/them. No expectations here though. I am content to build my usual way but when you introduce something new, I almost always want to 'tinker'. :-) Cheers!


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abrt-output.txt [16.7 KiB]
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buildlinux.log [23.82 KiB]
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2018-01-03 00:35:07
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Joined: 2009-03-17 18:42:51
Posts: 5523
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This is an issue with your distribution's building tools, not with the viewer. I suggest you report this bug to Fedora's folks.

Note that I can build the viewer with LTO on PCLinuxOS, with gcc v7.2.1 (+glibc 2.26), binutils v2.29.1 and cmake v3.10.1, and that it results in a 100% functional viewer (not really faster though, just a 10% smaller binary: 38Mb instead of 42Mb).
I can build it as well with gcc v5.5.0 and gcc 4.6.4 (the latter not really producing any smaller binary however: LTO is too crude in that old version to produce anything useful). gcc v4.9.4, on the other hand, chokes and stops on an internal error (gcc bug).
llvm/clang v5.0.1 also compiles the viewer with LTO just fine, but does not seem to produce any better binary (same size and speed).


2018-01-03 10:25:27
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Joined: 2016-06-19 21:33:37
Posts: 337
Location: Columbus area, OH, USA
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Henri Beauchamp wrote:
This is an issue with your distribution's building tools, not with the viewer. I suggest you report this bug to Fedora's folks.
Thanks Henri. I suspected it was my distro/tools rather than the viewer code since I can successfully build without using LTO. I'll see what I can dig up and/or report the bug to them.


2018-01-03 12:47:24
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