[llvm-dev] Undefined symbols in llvm-objdump linkage on x86_64-apple-darwin15

Tue May 24 12:03:28 PDT 2016

On Tue, May 24, 2016 at 2:37 PM, Jack Howarth
<howarth.mailing.lists at gmail.com> wrote:
> On Tue, May 24, 2016 at 2:28 PM, Chris Bieneman <beanz at apple.com> wrote:
>> Jack,
>>
>> What version of CMake are you using?
>>
>> -Chris
>
> Chris,
>       I am using cmake 3.5.2. My read of this problem is as follows.
> While libLLVM.dylib is being linked against -lxar when
> -DLLVM_LINK_LLVM_DYLIB:BOOL=ON is passed to cmake, the libLLVM.dylib
> is created with -Wl,-dead_strip such that any symbols from libxar not
> explicitly used with in the object files of libLLVM.dylib are stripped
> out. This means that those additional symbols used by llvm-objdump
> aren't accessible from libLLVM.dylib's linkage on libxar and an
> additional explicit linkage on libxar is required in the
> tools/llvm-objdump/CMakeLists.txt when HAVE_LIBXAR and
> LLVM_LINK_LLVM_DYLIB are set.
>         Jack

Also note that this issue doesn't arise for the cmake build with
-DBUILD_SHARED_LIBS:BOOL=ON because the resulting
lib/Object/CMakeFiles/LLVMObject.dir/link.txt contains...

/sw/src/fink.build/llvm39-3.9.0-1/opt-bin/ccclang++  -fno-common -fPIC
-fvisibility-inlines-hidden -Wall -W -Wno-unused-parameter
-Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic
-Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor
-Wdelete-non-virtual-dtor -Werror=date-time -std=c++11 -O3 -dynamiclib
-Wl,-headerpad_max_install_names  -Wl,-dead_strip  -L/sw/lib -o
../libLLVMObject.dylib -install_name @rpath/libLLVMObject.dylib
CMakeFiles/LLVMObject.dir/Archive.cpp.o
CMakeFiles/LLVMObject.dir/ArchiveWriter.cpp.o
CMakeFiles/LLVMObject.dir/Binary.cpp.o
CMakeFiles/LLVMObject.dir/COFFObjectFile.cpp.o
CMakeFiles/LLVMObject.dir/ELF.cpp.o
CMakeFiles/LLVMObject.dir/ELFObjectFile.cpp.o
CMakeFiles/LLVMObject.dir/Error.cpp.o
CMakeFiles/LLVMObject.dir/IRObjectFile.cpp.o
CMakeFiles/LLVMObject.dir/MachOObjectFile.cpp.o
CMakeFiles/LLVMObject.dir/MachOUniversal.cpp.o
CMakeFiles/LLVMObject.dir/ModuleSummaryIndexObjectFile.cpp.o
CMakeFiles/LLVMObject.dir/Object.cpp.o
CMakeFiles/LLVMObject.dir/ObjectFile.cpp.o
CMakeFiles/LLVMObject.dir/RecordStreamer.cpp.o
CMakeFiles/LLVMObject.dir/SymbolicFile.cpp.o
CMakeFiles/LLVMObject.dir/SymbolSize.cpp.o -lxar
../libLLVMBitReader.dylib ../libLLVMCore.dylib ../libLLVMMC.dylib
../libLLVMMCParser.dylib ../libLLVMSupport.dylib
-Wl,-rpath, at executable_path/../lib

and thus the linkage for  llvm-objdump is directly linked against
libxar as in the default static lib build. Only the
-DLLVM_LINK_LLVM_DYLIB:BOOL=ON build attempts to resolve the symbols
from libxar using an indirect linkage on libxar in libLLVM.dylib.
               Jack

>>
>>> On May 24, 2016, at 11:00 AM, Jack Howarth <howarth.mailing.lists at gmail.com> wrote:
>>>
>>> On Tue, May 24, 2016 at 1:35 PM, Kevin Enderby <enderby at apple.com> wrote:
>>>> Hi Jack,
>>>>
>>>> Just a guess here, this may be the bug Chris helped me out with in the use of the include file xar/xar.h which is not C++ safe.  I needed to wrap my include via:
>>>>
>>>> #ifdef HAVE_LIBXAR
>>>> extern "C" {
>>>> #include <xar/xar.h>
>>>> }
>>>> #endif
>>>>
>>>> I think we may need some help from Chris to track this down.  I’ll bug him in a bit to see if he can help us on this.
>>>
>>> While the build here with  -DLLVM_LINK_LLVM_DYLIB:BOOL=ON passed on
>>> the cmake options produces HAVE_LIBXAR:INTERNAL=1 in CMakeCache.txt, I
>>> don't see anything in the cmakefiles for tools/llvm-objdump to provide
>>> the necessary linkage on the system libxar shared library. Appending
>>> the missing linkage for -lxar onto
>>> build/stage1tools/llvm-objdump/CMakeFiles/llvm-objdump.dir/link.txt...
>>>
>>> /sw/src/fink.build/llvm39-3.9.0-1/opt-bin/ccclang++   -fno-common
>>> -fPIC -fvisibility-inlines-hidden -Wall -W -Wno-unused-parameter
>>> -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic
>>> -Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor
>>> -Wdelete-non-virtual-dtor -Werror=date-time -std=c++11 -O3
>>> -Wl,-search_paths_first -Wl,-headerpad_max_install_names  -L/sw/lib
>>> -Wl,-dead_strip CMakeFiles/llvm-objdump.dir/llvm-objdump.cpp.o
>>> CMakeFiles/llvm-objdump.dir/COFFDump.cpp.o
>>> CMakeFiles/llvm-objdump.dir/ELFDump.cpp.o
>>> CMakeFiles/llvm-objdump.dir/MachODump.cpp.o  -o ../../bin/llvm-objdump
>>> ../../lib/libLLVM.dylib -Wl,-rpath, at executable_path/../lib -lxar
>>>
>>> eliminates the bootstrap failure.
>>>
>>>>
>>>> Kev
>>>>
>>>>> On May 24, 2016, at 10:28 AM, Jack Howarth <howarth.mailing.lists at gmail.com> wrote:
>>>>>
>>>>> On Tue, May 24, 2016 at 1:24 PM, Jack Howarth
>>>>> <howarth.mailing.lists at gmail.com> wrote:
>>>>>> On Tue, May 24, 2016 at 1:22 PM, Jack Howarth
>>>>>> <howarth.mailing.lists at gmail.com> wrote:
>>>>>>> On Tue, May 24, 2016 at 12:08 PM, Reid Kleckner <rnk at google.com> wrote:
>>>>>>>> Kevin Enderby added those symbol uses in r270491. It has a cmake
>>>>>>>> feature test, and all the uses of those symbols appear bracketed in
>>>>>>>> HAVE_LIBXAR, so I don't know what went wrong for you.
>>>>>>>
>>>>>>> The trigger for this build failure is the usage of
>>>>>>> -DLLVM_BUILD_EXTERNAL_COMPILER_RT:BOOL=ON. If I drop that cmake
>>>>>>> option, the linkage failure for llvm-objdump disappears.
>>>>>>
>>>>>> Wrong cmake option. I meant to say that -DLLVM_LINK_LLVM_DYLIB:BOOL=ON
>>>>>> is the trigger of the build failure. Sorry for the noise there.
>>>>>
>>>>> Filed as https://llvm.org/bugs/show_bug.cgi?id=27855
>>>>>
>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> On Tue, May 24, 2016 at 8:07 AM, Jack Howarth via llvm-dev
>>>>>>>> <llvm-dev at lists.llvm.org> wrote:
>>>>>>>>> Is anyone else seeing a bootstrap failure on x86_64-apple-darwin15 in
>>>>>>>>> current trunk?
>>>>>>>>>
>>>>>>>>> [ 95%] Linking CXX executable ../../bin/llvm-objdump
>>>>>>>>> Undefined symbols for architecture x86_64:
>>>>>>>>> "_xar_serialize", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_file_first", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_iter_new", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_prop_first", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_extract_tobuffersz", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_open", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_prop_get", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_close", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_prop_next", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_iter_free", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> "_xar_file_next", referenced from:
>>>>>>>>>     DumpBitcodeSection(llvm::object::MachOObjectFile*, char const*,
>>>>>>>>> unsigned int, bool, bool, bool, std::__1::basic_string<char,
>>>>>>>>> std::__1::char_traits<char>, std::__1::allocator<char> >) in
>>>>>>>>> MachODump.cpp.o
>>>>>>>>> ld: symbol(s) not found for architecture x86_64
>>>>>>>>> clang: error: linker command failed with exit code 1 (use -v to see invocation)
>>>>>>>>> tools/llvm-objdump/CMakeFiles/llvm-objdump.dir/build.make:173: recipe
>>>>>>>>> for target 'bin/llvm-objdump' failed
>>>>>>>>> make[2]: *** [bin/llvm-objdump] Error 1
>>>>>>>>> make[2]: Target 'tools/llvm-objdump/CMakeFiles/llvm-objdump.dir/build'
>>>>>>>>> not remade because of errors.
>>>>>>>>> CMakeFiles/Makefile2:21861: recipe for target
>>>>>>>>> 'tools/llvm-objdump/CMakeFiles/llvm-objdump.dir/all' failed
>>>>>>>>> make[1]: *** [tools/llvm-objdump/CMakeFiles/llvm-objdump.dir/all] Error 2
>>>>>>>>> _______________________________________________
>>>>>>>>> LLVM Developers mailing list
>>>>>>>>> llvm-dev at lists.llvm.org
>>>>>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>
>>