[Bug lto/65015] New: LTO produces randomly ordered debug information

["conchur at web dot de" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65015

            Bug ID: 65015
           Summary: LTO produces randomly ordered debug information
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: conchur at web dot de

I was discussing with the Debian Reproducible Builds people some problem that
I've noticed (only) with LTO builds. The build id (and debug link) was changing
all the time and Jérémy Bobbio suggested that one reason for this problem are
the odd filenames in the debug sections.

I was able to workaround this special problem by using -flto-partition=none

But now I still have differences in the debug sections. I tried to narrow it
down, uncompressed it and found out that both files have the same size. And
things like the debug_str sections have common parts but oddly (random?)
ordered.

This currently makes LTO unsuitable for reproducible builds on Debian (amd64,
and most likely all other architectures).

I was not able to find any related bug in the meta bug #47819. Maybe it should
be added there. My discussion of the findings can be found at
http://lists.alioth.debian.org/pipermail/reproducible-builds/Week-of-Mon-20150209/000933.html
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Subject: [Bug middle-end/64824] ICE in gimple verification
Date: Wed, 11 Feb 2015 10:11:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd824

--- Comment #6 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to Jakub Jelinek from comment #5)
> What does #c3 have to do with this?

Same ice, so I guessed same problem.

>I don't see any OpenMP pragmas in your code, therefore it can't be related to >this.  File a new PR?

Done. #65014