compiled program segfault when -O0 is used to compile

[Kaylee Hirsch]

I don't know whether this is really a problem, or what not, but I'm attaching logs, and the program which causes it, along with every detail I can think of. When I compile my code, if I compile it -O2, it compiles and runs fine. if I compile it with -O0, it segfaults very early on in the execution. I've made no changes to anything in between compiles.

Compiling the code successfully requires the following libraries:
opengl (mesa)
glut (freeglut)
curl
FTGL (patched, see https://bugs.launchpad.net/ubuntu/+source/ftgl/+bug/485225 )

procedure is as follows:

./configure
make CFLAGS="-O0"
src/altocumulus

make clean
make CFLAGS="-O2"
src/altocumulus

My code is pretty crappy, please ignore that, I'm still learning the basics of C.
Regardless, the code shouldn't work with one level of optimization and fail with another.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: gcc 4:4.4.3-1ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-22.36-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-22-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Wed Jun 9 11:43:21 2010
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: gcc-defaults

[eviom (eviom)]

I have the same problem on both ubuntu 10.04 (not updated, gcc 4.4.3) and ubuntu 11.04 (fully updated, can't check the gcc version right now). According to gdb it crashes in some TFGlyth member function. I really did not expect such problem from gcc...
BTW thanks for the solution, I thought the problem was somwhere in my code.

[eviom (eviom)]

Original thread: https://bugs.launchpad.net/ubuntu/+source/gcc-defaults/+bug/591819

When I compile my code, if I compile it -O2, it compiles and runs fine. if I compile it with -O0, it segfaults while rendering text with FTGL. I've made no changes to anything in between compiles. Same FTGL code works fine in win32 (vs2010).

[eviom (eviom)]

I have submitted it to gcc bugzilla. Here is the thread link:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50239

[Paolo-carlini (paolo-carlini)]

Please follow the normal bug reporting instructions:

  http://gcc.gnu.org/bugs/#report

[eviom (eviom)]

When I compile my code, if I compile it -O2, it compiles and runs fine. if I
compile the code without it, my program segfaults while rendering text with FTGL. I've made no changes to anything in between compiles. Same FTGL code works fine in win32 (vs2010).

system: ubuntu 11.04 & 10.04
gcc version: 4.5.2 (from deb package)
command line: gcc -I /usr/include/freetype2 -o ~/BlocksWorld/BlocksWorld Src/*.cpp Src/Linux/*.cpp Src/GUI/*.cpp -lpng -lGL -lGLU -lftgl

[Redi (redi)]

There's no need to repeat the same info you already provided, please provide what you _didn't_ provide, as requested by http://gcc.gnu.org/bugs/#report

we need preprocessed source, and preferably a minimal testcase that has been reduced to the smallest example that still shows the problem

[Paolo-carlini (paolo-carlini)]

Feedback not forthcoming.

[Matthias Klose (doko)]

no feedback