FYI I have also submitted a bug report on GCC Bugzilla [1]
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53439
On Mon, May 21, 2012 at 11:31 AM, Christophe Prud'homme <prudhomm@debian.org> wrote:
Please note that**- Debug -g
*- RelWithDebInfo uses -g -O1**- Release uses -O3
there must be an option in -O1 that generates the buggy code.
Best regardsC.
On Mon, May 21, 2012 at 10:34 AM, Christophe Prud'homme <prudhomm@debian.org> wrote:
Package: g++-4.7
Version: 4.7.0-8
Severity: normal
Tags: upstream
Dear Maintainer,
* * What led up to the situation?
I ported feel++ to gcc47 and found out that it generates buggy code(generating
segfault) in optimisation mode.
Here are the steps to reproduce it
*- install feel++-apps
*- execute feel_doc_myfunctionspace (compiled using CMAKE_BUILD_TYPE=Release)
*- it generates a segfault
what happens is that a data structure containing only a double data member seem
to be optimized away and became dangling reference (invalid read using
valgrind).
The code crashes at line 220 of doc/manual/tutorial/myfunctionspace.cpp when
evaluating the _expression_ template data structure g defined on line 215.
*- in gcc47 with CMAKE_BUILD_TYPE=Debug, it works without problems
*- with gcc45, gcc46, clang31 on Linux and OSX there are no problems at all
* in RelWithDebInfo and Release mode (CMAKE_BUILD_TYPE)
Hence I believe that this is a bug in gcc47 code generation/optimisation.
-- System Information:
Debian Release: wheezy/sid
*APT prefers unstable
*APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)
Kernel: Linux 3.2.0-2-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages g++-4.7 depends on:
ii *gcc-4.7 * * * * * * 4.7.0-8
ii *gcc-4.7-base * * * *4.7.0-8
ii *libc6 * * * * * * * 2.13-32
ii *libgmp10 * * * * * *2:5.0.5+dfsg-1.1
ii *libmpc2 * * * * * * 0.9-4
ii *libmpfr4 * * * * * *3.1.0-5
ii *libstdc++6-4.7-dev *4.7.0-8
ii *zlib1g * * * * * * *1:1.2.7.dfsg-2
g++-4.7 recommends no packages.
Versions of packages g++-4.7 suggests:
pn *g++-4.7-multilib * *<none>
pn *gcc-4.7-doc * * * * <none>
pn *libstdc++6-4.7-dbg *<none>
-- no debconf information
Bug#673749: g++-4.7: gcc47 generates buggy code with optimisation flags
