[CMake] Add $ORIGIN/../../../../lib to rpath if BUILD_SHARED_LIBS or LLVM_LINK_LLVM_DYLIB on *nix

[MaskRay]

Summary

lib/python2.7/dist-packages/lldb/_lldb.so is a symlink to lib/liblldb.so,
which depends on lib/libLLVM*.so (-DBUILD_SHARED_LIBS=ON) or lib/libLLVM-10git.so
(-DLLVM_LINK_LLVM_DYLIB=ON). Add an additional rpath $ORIGIN/../../../../lib so
that _lldb.so can be loaded from Python.

This fixes an import error from lib/python2.7/dist-packages/lldb/__init__.py

from . import _lldb
ImportError: libLLVMAArch64CodeGen.so.10git: cannot open shared object file: No such file or directory

The following configurations will work:

• -DBUILD_SHARED_LIBS=ON
• -DBUILD_SHARED_LIBS=OFF -DLLVM_LINK_LLVM_DYLIB=ON
• -DBUILD_SHARED_LIBS=OFF -DLLVM_LINK_LLVM_DYLIB=ON -DCLANG_LINK_CLANG_DYLIB=ON (-DCLANG_LINK_CLANG_DYLIB=ON depends on -DLLVM_LINK_LLVM_DYLIB=ON)

[MaskRay]

lldb/source/API/CMakeLists.txt

124

The extra_libdir logic is copied from llvm/cmake/modules/AddLLVM.cmake llvm_setup_rpath.

[labath]

Yeah, not requiring LD_LIBRARY_PATH in the BUILD_SHARED_LIBS build would be nice. The fix isn't particularly pretty, but I don't know if there is a better way to do that (besides the improvements in inline comments).

lldb/source/API/CMakeLists.txt

117

I think this would work on APPLE (which is subsumed by UNIX). Though I don't know if anyone there actually uses BUILD_SHARED_LIBS...

124

Instead of copying that you should do something like set_property(TARGET liblldb APPEND PROPERTY INSTALL_RPATH "whatever") to just add the new entry.

[labath]

BTW, isn't a LLVM_LINK_LLVM_DYLIB build suffering from the same problem? Should that be included here too?

[MaskRay]

Make -DLLVM_LINK_LLVM_DYLIB=ON work

lldb/source/API/CMakeLists.txt

117

I assume APPLE -DBUILD_SHARED_LIBS=On works as-is. I will add AND NOT APPLE.

124

Thanks for the suggestion! Will apply.

[MaskRay]

Ping:)

[labath]

Thanks. I think this is fine now.

lldb/source/API/CMakeLists.txt

LINK_LIBS
     lldbUtility
     ${LLDB_ALL_PLUGINS}
   LINK_COMPONENTS
     Support
 
   ${option_install_prefix}
 )
 
+# lib/pythonX.Y/dist-packages/lldb/_lldb.so is a symlink to lib/liblldb.so .
+# Add an additional rpath \$ORIGIN/../../../../lib so that _lldb.so can be
+# loaded from Python.
+if(LLDB_ENABLE_PYTHON AND BUILD_SHARED_LIBS AND UNIX)
+  if(LLVM_INSTALL_PREFIX AND NOT (LLVM_INSTALL_PREFIX STREQUAL CMAKE_INSTALL_PREFIX))
+    set(extra_libdir ${LLVM_LIBRARY_DIR})
+  elseif(LLVM_BUILD_LIBRARY_DIR)
+    set(extra_libdir ${LLVM_LIBRARY_DIR})
+  endif()
+  set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" "\$ORIGIN/../../../../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+  set_target_properties(liblldb PROPERTIES INSTALL_RPATH "${_install_rpath}")
+endif()
+
 if (MSVC)
   set_source_files_properties(SBReproducer.cpp PROPERTIES COMPILE_FLAGS /bigobj)
 endif()
 
 if(lldb_python_wrapper)
   add_dependencies(liblldb swig_wrapper)
 
   if (MSVC)