After compiling a particular C++ program (see attachment) both with and without the -O option, the program produces different results.
When compiled with -O, the program produces the output "(nil)", whereas when compiled without any options, the program prints a non-null pointer (which may of course vary between runs). The program is only 121 lines long, and was obtained by reducing an initial set of over 30.000 lines of code until no further reduction seemed to be possible without suppressing the problem. For example, by moving the static variable " fs_active_handle" into the main function, the problem "magically" disappears. Also, when adding printf-statements to the functions, or by manually inlining certain constructs, the problem disappears. Due to the immense reduction of the code, the semantics of the code may not seem clear anymore (that is, I am myself not sure what this program is supposed to do anymore), but the problem with the optimizer clearly shows. I have tried to use the tool valgrind to see if something illegal is happening wrt copy-constructors/assignment operators (despite close inspection), but this does not seem to be the case. -- Summary: optimizer bug (possibly) Product: gcc Version: 4.4.0 Status: UNCONFIRMED Severity: critical Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: keesjan at cobalt dot et dot tudelft dot nl GCC build triplet: x86_64-unknown-linux-gnu GCC host triplet: x86_64-unknown-linux-gnu GCC target triplet: x86_64-unknown-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40389