Compiling source code for debugging (KDevelop/cmake)

deadeyes · 12-10-2010, 04:56 AM

Hi all,

I want to make a small improvement to the Krdc source code.
For that I want to debug the code.
However after building the binary file, gdb krdc,
setting a breakpoint and make the breakpoint being triggered... I step through the code and I want to use the print function to see the value of an integer.

I get the message:

<Value optimized out>

After a short search I noticed this is due to optimizations in the compilation code and the debugger not being able to read the value out.

I am using gentoo so I know about the -O option.
I created the project in KDevelop as a "Debug" project.

I changed some flags in the "Open Options", "Advanced settings" to use -O0.
CMAKE_CXX_FLAGS
CMAKE_CXX_FLAGS_DEBUG
CMAKE_C_FLAGS
CMAKE_C_FLAGS_DEBUG
...
Even then I still get the same issue.

DOes someone know what I should do? (I am not experienced with debugging and programming)
Thanks in advance!

ntubski · 12-11-2010, 11:51 AM

You may need to do a make clean after changing the flags to force the object files to be recompiled with the new optimization settings. You may need to recompile the libraries used by the program as well.

deadeyes · 12-11-2010, 05:59 PM

Thanks for your answer.

I did make clean all. The libraries shouldn't be recompiled as the code I want to debug is not in any library.
I am still searching for a solution

EDIT:
I found out that the issue is actually due to cmake/default cxx flags.

Code:

#
/usr/bin/cmake -E cmake_echo_color --switch= --green "Building CXX object rdp/CMakeFiles/krdc_rdpplugin.dir/rdpview.o"
#
cd /home/xxx/kdenetwork-4.4.5/krdc/build/rdp && /usr/bin/c++   -DMAKE_KRDC_RDPPLUGIN_LIB -D_BSD_SOURCE -D_XOPEN_SOURCE=500 -D_BSD_SOURCE -DQT_NO_STL -DQT_NO_CAST_TO_ASCII -D_REENTRANT -DKDE_DEPRECATED_WARNINGS -DKDE_DEFAULT_DEBUG_AREA=5012 -g3 -O0 -Wnon-virtual-dtor -Wno-long-long -ansi -Wundef -Wcast-align -Wchar-subscripts -Wall -W -Wpointer-arith -Wformat-security -fno-exceptions -DQT_NO_EXCEPTIONS -fno-check-new -fno-common -Woverloaded-virtual -fno-threadsafe-statics -fvisibility=hidden -fvisibility-inlines-hidden -g -O2 -fno-reorder-blocks -fno-schedule-insns -fno-inline -fPIC -I/home/xxx/kdenetwork-4.4.5/krdc/build/rdp -I/home/xxx/kdenetwork-4.4.5/krdc/rdp -I/home/xxx/kdenetwork-4.4.5/krdc -I/home/xxx/kdenetwork-4.4.5/krdc/build -I/home/xxx/kdenetwork-4.4.5/krdc/core -I/home/xxx/kdenetwork-4.4.5/krdc/build/core -I/usr/include/KDE -I/usr/include/qt4/QtXmlPatterns -I/usr/include/qt4/QtXml -I/usr/include/qt4/QtWebKit -I/usr/include/qt4/QtUiTools -I/usr/include/qt4/QtTest -I/usr/include/qt4/QtSvg -I/usr/include/qt4/QtSql -I/usr/include/qt4/QtScriptTools -I/usr/include/qt4/QtScript -I/usr/include/qt4/QtOpenGL -I/usr/include/qt4/QtNetwork -I/usr/include/qt4/QtHelp -I/usr/include/qt4/QtDesigner -I/usr/include/qt4/QtDBus -I/usr/include/qt4/QtAssistant -I/usr/include/qt4/Qt3Support -I/usr/include/qt4/QtGui -I/usr/include/qt4/QtCore -I/usr/include/qt4/Qt -I/usr/share/qt4/mkspecs/default -I/usr/include/qt4   -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -o CMakeFiles/krdc_rdpplugin.dir/rdpview.o -c /home/xxx/kdenetwork-4.4.5/krdc/rdp/rdpview.cpp

There is both -g3 -O0 and -g -O2 after that. However I don't know how to fix this.

ntubski · 12-13-2010, 06:01 PM

Quote:

Originally Posted by deadeyes

There is both -g3 -O0 and -g -O2 after that. However I don't know how to fix this.

The last option is the one that takes effect, can you see how cmake is constructing that command line (post the cmakefile, maybe)?

deadeyes · 12-14-2010, 07:25 AM

Quote:

Originally Posted by ntubski

The last option is the one that takes effect, can you see how cmake is constructing that command line (post the cmakefile, maybe)?

Someone pointed out that FindKDE4Internal.cmake is the actual cause.
I grepped for CMAKE_CXX_FLAGS_DEBUG and found that -g -O2 is configured there.

I changed it in that file. Of course it is more of a workaround than a fix so if you have any ideas on how to fix this I would be happy to hear it.

Is CMakeLists what you want?

Code:

project(krdc)

if(NOT INSIDE_KDENETWORK)
    message("Not building inside KDENetwork, loading KDE CMake Macros.")

    set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/../cmake/modules ${CMAKE_MODULE_PATH})

    find_package(KDE4 REQUIRED)

    include(KDE4Defaults)
    include(MacroLibrary)

    include(CheckIncludeFile)
    include(CheckIncludeFiles)
    include(CheckSymbolExists)
    include(CheckFunctionExists)
    include(CheckLibraryExists)
    include(CheckPrototypeExists)
    include(CheckTypeSize)

    macro_optional_find_package(TelepathyQt4)
    macro_log_feature(TELEPATHY_QT4_FOUND "telepathy-qt4" "Telepathy Qt Bindings" "https://telepathy.freedesktop.org" FALSE "0.18" "Needed to build Telepathy Tubes support.")

    set(CMAKE_REQUIRED_DEFINITIONS ${_KDE4_PLATFORM_DEFINITIONS})
    if(WIN32)
       set(CMAKE_REQUIRED_LIBRARIES ${KDEWIN32_LIBRARIES})
       set(CMAKE_REQUIRED_INCLUDES  ${KDEWIN32_INCLUDES})
    endif(WIN32)
    add_definitions(${QT_DEFINITIONS} ${QT_QTDBUS_DEFINITIONS} ${KDE4_DEFINITIONS})
    include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR} ${KDE4_INCLUDES})

    macro_optional_find_package(LibVNCServer)
    macro_log_feature(LIBVNCSERVER_FOUND "libvncserver" "VNC Server library" "http://libvncserver.sourceforge.net/" FALSE "0.9" "Needed to build Krfb and VNC support in Krdc")

    # NX support is not ready for KDE 4.2; disabled (uwolfer)
    # macro_optional_find_package(LibNXCL)
    # macro_log_feature(LIBNXCL_FOUND "libnxcl" "NX X compression client library" "http://svn.berlios.de/svnroot/repos/freenx/trunk/freenx-client/nxcl/" FALSE "1.0" "Needed to build Krdc with NX support")

	if(TELEPATHY_QT4_FOUND)
    	add_definitions(-DTELEPATHY_SUPPORT)
    	include_directories(${TELEPATHY_QT4_INCLUDE_DIR})
	endif(TELEPATHY_QT4_FOUND)

endif(NOT INSIDE_KDENETWORK)

include_directories(
    ${CMAKE_CURRENT_SOURCE_DIR}
    ${CMAKE_CURRENT_SOURCE_DIR}/core/
    ${CMAKE_CURRENT_BINARY_DIR}/core/
    ${CMAKE_CURRENT_BINARY_DIR}
)

add_subdirectory(core)
add_subdirectory(vnc)
add_subdirectory(nx)
add_subdirectory(rdp)
add_subdirectory(test)

if(TELEPATHY_QT4_FOUND)
    add_subdirectory(krdc_approver)
endif(TELEPATHY_QT4_FOUND)

add_definitions(-DKDE_DEFAULT_DEBUG_AREA=5010)
add_definitions(-DBUILD_ZEROCONF)

set(krdc_SRCS
    config/hostpreferenceslist.cpp
    config/preferencesdialog.cpp
    floatingtoolbar.cpp
    bookmarkmanager.cpp
    remotedesktopsitem.cpp
    remotedesktopsmodel.cpp
    systemtrayicon.cpp
    tabbedviewwidget.cpp
    mainwindow.cpp
    main.cpp
)

if(TELEPATHY_QT4_FOUND)
    set(krdc_SRCS ${krdc_SRCS}
        tubesmanager.cpp
        tube.cpp
    )
endif(TELEPATHY_QT4_FOUND)

kde4_add_ui_files(krdc_SRCS
    config/general.ui
)

kde4_add_executable(krdc ${krdc_SRCS})

target_link_libraries(krdc
    ${KDE4_KFILE_LIBS}
    ${KDE4_KIO_LIBS}
    ${KDE4_KNOTIFYCONFIG_LIBS}
    ${KDE4_KUTILS_LIBS}
    krdccore
)

if(TELEPATHY_QT4_FOUND)
    target_link_libraries(krdc
        ${TELEPATHY_QT4_LIBRARIES}
    )
endif(TELEPATHY_QT4_FOUND)

target_link_libraries(krdc ${KDE4_KDNSSD_LIBS})

install(TARGETS krdc ${INSTALL_TARGETS_DEFAULT_ARGS})
install(FILES krdcui.rc DESTINATION ${DATA_INSTALL_DIR}/krdc)
install(FILES krdc.desktop DESTINATION ${XDG_APPS_INSTALL_DIR})
install(FILES pointcursor.png pointcursormask.png DESTINATION ${DATA_INSTALL_DIR}/krdc/pics)

if(TELEPATHY_QT4_FOUND)
    configure_file(org.freedesktop.Telepathy.Client.krdc_rfb_handler.service.in
                    ${CMAKE_CURRENT_BINARY_DIR}/org.freedesktop.Telepathy.Client.krdc_rfb_handler.service)
    install(FILES ${CMAKE_CURRENT_BINARY_DIR}/org.freedesktop.Telepathy.Client.krdc_rfb_handler.service
            DESTINATION ${DBUS_SERVICES_INSTALL_DIR})

    install(FILES krdc_rfb_handler.client DESTINATION ${SHARE_INSTALL_PREFIX}/telepathy/clients/)
endif(TELEPATHY_QT4_FOUND)

if(NOT INSIDE_KDENETWORK)
    macro_display_feature_log()
endif(NOT INSIDE_KDENETWORK)

Thanks in advance!

ntubski · 12-14-2010, 02:49 PM

Quote:

Originally Posted by deadeyes

Someone pointed out that FindKDE4Internal.cmake is the actual cause.
I grepped for CMAKE_CXX_FLAGS_DEBUG and found that -g -O2 is configured there.

I changed it in that file. Of course it is more of a workaround than a fix so if you have any ideas on how to fix this I would be happy to hear it.

Given that

Quote:

KDevelop does not yet support modifing the CMake build system. This means you can not use KDevelop to add or remove files from the project or to change any other aspect of your project's build process.

a workaround is required, but it may be cleaner to set CMAKE_CXX_FLAGS_DEBUG in your own cmake file rather than in the KDE internals.