[Bug tree-optimization/71867] Optimizer generates code dereferencing a null pointer

[asmwarrior at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71867

--- Comment #9 from asmwarrior <asmwarrior at gmail dot com> ---
I see this crash issue again, but still it happens in another place of the wx's
source code, add the

__attribute__((optimize("O0")))

To the function which cause the crash can workaround this issue. Note that the
-O0 option does not cause this issue.

wxString __attribute__((optimize("O0"))) wxCommandEvent::GetString() const
{
    // This is part of the hack retrieving the event string from the control
    // itself only when/if it's really needed to avoid copying potentially huge
    // strings coming from multiline text controls. For consistency we also do
    // it for combo boxes, even though there are no real performance advantages
    // in doing this for them.
    if (m_eventType == wxEVT_TEXT && m_eventObject)
    {
#if wxUSE_TEXTCTRL
        wxTextCtrl *txt = wxDynamicCast(m_eventObject, wxTextCtrl);
        if ( txt )
            return txt->GetValue();
#endif // wxUSE_TEXTCTRL

#if wxUSE_COMBOBOX
        wxComboBox* combo = wxDynamicCast(m_eventObject, wxComboBox);
        if ( combo )
            return combo->GetValue();
#endif // wxUSE_COMBOBOX
    }

    return m_cmdString;
} 

Please see discussions here in wx-user's maillist and Code::Blocks's forum:

https://groups.google.com/d/msg/wx-users/LUxm6fUhirk/FJRFNIt6AAAJ

and 

http://forums.codeblocks.org/index.php/topic,22198.0.html

The original wx's workaround is here: https://trac.wxwidgets.org/ticket/17483