[lldb] Enable building with Cmake/BUILD_SHARED_LIBS

[axw]

Summary

Several changes to fix CMake builds of LLDB with the
BUILD_SHARED_LIBS setting on.

• Force all internal libraries to be built STATIC.
• Add additional library dependencies (pthread, dl, runtimedyld).
• modify finalisation of SWIG wrapper to symlink the "lib" dir into python/site-packages, so _lldb.so's RPATH resolves.

[zturner]

Would it be easier instead of modifying every CMakeLists.txt file -- which has the con of requiring every person to remember to make future CMakeLists.txt files include this keyword as well -- to just kill support for BUILD_SHARED_LIBS at the CMake level, and have static be the default?

In other words, change add_lldb_library to just force static.

BUILD_SHARED_LIBS is completely broken in LLDB, and as you pointed out on the email thread, there is no way to make it work due to the circular dependencies that are pervasive throughout the codebase. So I think we should just remove it.

[axw]

In D10157#181897, @zturner wrote:

Would it be easier instead of modifying every CMakeLists.txt file -- which has the con of requiring every person to remember to make future CMakeLists.txt files include this keyword as well -- to just kill support for BUILD_SHARED_LIBS at the CMake level, and have static be the default?

In other words, change add_lldb_library to just force static.

BUILD_SHARED_LIBS is completely broken in LLDB, and as you pointed out on the email thread, there is no way to make it work due to the circular dependencies that are pervasive throughout the codebase. So I think we should just remove it.

Certainly easier and less error-prone; I wasn't sure if precluding either/or static/shared would be acceptable. I'll change it to do that.

[axw]

Default add_lldb_library to STATIC

[sylvestre.ledru]

I tried your patch but it does not generate libLLVM-3.7.so like autotool is. Is that expected?

[axw]

In D10157#182280, @sylvestre.ledru wrote:

I tried your patch but it does not generate libLLVM-3.7.so like autotool is. Is that expected?

This patch is only addressing issues with building LLDB.

There are some other differences between autotools and CMake builds, but this patch doesn't address them. There is lib/libLLVM.so.3.7, but no lib/libLLVM-3.7.so. In the CMake build, tools such as lldb link against the individual component shared libraries anyway:

$ ldd bin/lldb
linux-vdso.so.1 =>  (0x00007ffd203f5000)
liblldb.so.3.7 => /home/andrew/code/src/llvm.org/build/bin/../lib/liblldb.so.3.7 (0x00007fb8badcf000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fb8baa9e000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fb8ba6d3000)
libLLVMX86CodeGen.so.3.7 => /home/andrew/code/src/llvm.org/build/bin/../lib/../lib/libLLVMX86CodeGen.so.3.7 (0x00007fb8ba146000)
libLLVMX86Desc.so.3.7 => /home/andrew/code/src/llvm.org/build/bin/../lib/../lib/libLLVMX86Desc.so.3.7 (0x00007fb8b9d8e000)
libLLVMX86Info.so.3.7 => /home/andrew/code/src/llvm.org/build/bin/../lib/../lib/libLLVMX86Info.so.3.7 (0x00007fb8b9b8b000)
(etc...)

(I'm not sure if this is desirable, but it's just how things are currently.)

[zturner]

scripts/Python/finishSwigPythonLLDB.py

307–308

I'm having some trouble visualizing what this is doing. What do a sample strSrc and strTarget look like before and after this change? (i.e. what was broken that this is fixing?)

376–380

I think this shouldn't be done on Windows. Windows doesn't have a notion of RPATH or LD_LIBRARY_PATH.

tools/lldb-server/CMakeLists.txt

32–34

Should this be

if (HAVE_LIBPTHREAD)

?

[axw]

• HAVE_LIBPTHREAD instead of Windows check
• Don't create lib symlink on Windows

scripts/Python/finishSwigPythonLLDB.py

307–308

Without this change, the "lib" symlink looks like this:

$ readlink lib/python2.7/site-packages/lib
../../../../lib

which is one too many ".."s. The problem is that the symlinks are being created relative to site-packages/lldb, rather than where the symlink is located. It just happened that all the symlinks were in site-packages/lldb before.

This change makes the source relative to the target, since that's how the symlink will be followed.

376–380

Fixed.

tools/lldb-server/CMakeLists.txt

32–34

Done.

[zturner]

Lgtm

[axw]

In D10157#182787, @zturner wrote:

Lgtm

Thanks! Are you able to accept the revision so I can commit?

cmake/LLDBDependencies.cmake

set( LLVM_LINK_COMPONENTS
   ipo
   selectiondag
   bitreader
   mc
   mcjit
   core
   mcdisassembler
   executionengine
+  runtimedyld
   option
   support
   )
 
 if ( NOT LLDB_DISABLE_PYTHON )
   set(LLDB_WRAP_PYTHON ${LLDB_BINARY_DIR}/scripts/LLDBWrapPython.cpp)
 
   set_source_files_properties(${LLDB_WRAP_PYTHON} PROPERTIES GENERATED 1)

cmake/modules/AddLLDB.cmake

if (MSVC_IDE OR XCODE)
     file(GLOB_RECURSE headers
       ../../include/lldb${dir}/*.h)
     set(srcs ${srcs} ${headers})
   endif()
   if (PARAM_MODULE)
     set(libkind MODULE)
   elseif (PARAM_SHARED)
     set(libkind SHARED)
-  elseif (PARAM_STATIC)
-    set(libkind STATIC)
   elseif (PARAM_OBJECT)
     set(libkind OBJECT)
   else ()
-    # library type unspecified - controlled by BUILD_SHARED_LIBS
-    unset(libkind)
+    # PARAM_STATIC or library type unspecified. BUILD_SHARED_LIBS
+    # does not control the kind of libraries created for LLDB,
+    # only whether or not they link to shared/static LLVM/Clang
+    # libraries.
+    set(libkind STATIC)
   endif()
 
   #PIC not needed on Win
   if (NOT MSVC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC")
   endif()
 
   if (PARAM_OBJECT)

cmake/modules/LLDBConfig.cmake

else()
   if (LIBXML2_FOUND)
     add_definitions( -DLIBXML2_DEFINED )
     list(APPEND system_libs ${LIBXML2_LIBRARIES})
     include_directories(${LIBXML2_INCLUDE_DIR})
   endif()
 
 endif()
 
+if (HAVE_LIBPTHREAD)
+  list(APPEND system_libs pthread)
+endif(HAVE_LIBPTHREAD)
+
+if (HAVE_LIBDL)
+  list(APPEND system_libs ${CMAKE_DL_LIBS})
+endif()
+
 if(LLDB_REQUIRES_EH)
   set(LLDB_REQUIRES_RTTI ON)
 else()
   if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
     set(LLDB_COMPILE_FLAGS "${LLDB_COMPILE_FLAGS} -fno-exceptions")
   elseif(MSVC)
     add_definitions( -D_HAS_EXCEPTIONS=0 )
     set(LLDB_COMPILE_FLAGS "${LLDB_COMPILE_FLAGS} /EHs-c-")

scripts/Python/finishSwigPythonLLDB.py

else:
             # On a Windows platform the vstrFrameworkPythonDir looks like:
             # llvm\\build\\Lib\\site-packages\\lldb
             strBuildDir = os.path.join("..", "..", "..");
         else:
             # On a UNIX style platform the vstrFrameworkPythonDir looks like:
             # llvm/build/lib/python2.7/site-packages/lldb
             strBuildDir = os.path.join("..", "..", "..", "..");
         strSrc = os.path.normcase(os.path.join(strBuildDir, vstrSrcFile));
+        strTargetDir = os.path.dirname(strTarget);
+        strSrc = os.path.relpath(os.path.abspath(strSrc), strTargetDir);
 
     if eOSType == utilsOsType.EnumOsType.Unknown:
         bOk = False;
         strErrMsg = strErrMsgOsTypeUnknown;
     elif eOSType == utilsOsType.EnumOsType.Windows:
         if os.path.isfile( strTarget ):
             if bDbg:
                 print strMsgSymlinkExists % vstrTargetFile;
else:
             strSrc = os.path.join("bin", "liblldb.dll");
         else:
             if eOSType == utilsOsType.EnumOsType.Darwin:
                 strLibFileExtn = ".dylib";
             else:
                 strLibFileExtn = ".so";
             strSrc = os.path.join("lib", "liblldb" + strLibFileExtn);
 
+    # Create a symlink to the "lib" directory, to ensure liblldb's RPATH is
+    # effective.
+    bOk, strErrMsg = make_symlink( vDictArgs, vstrFrameworkPythonDir, "lib", os.path.join("../lib") );
+    if not bOk:
+        return (bOk, strErrMsg)
+
     bOk, strErrMsg = make_symlink( vDictArgs, vstrFrameworkPythonDir, strSrc, strTarget );
 
     return (bOk, strErrMsg);
 
 #++---------------------------------------------------------------------------
 # Details:  Make the symbolic link to the darwin-debug.
 # Args:     vDictArgs               - (R) Program input parameters.
 #           vstrFrameworkPythonDir  - (R) Python framework directory.

tools/lldb-server/CMakeLists.txt

if (BUILD_SHARED_LIBS )
   add_lldb_executable(lldb-server
     lldb-gdbserver.cpp
     lldb-platform.cpp
     lldb-server.cpp
     LLDBServerUtilities.cpp
     )
 
   target_link_libraries(lldb-server liblldb)
+  if (NOT CMAKE_SYSTEM_NAME MATCHES "Windows")
+    target_link_libraries(lldb-server pthread)
+  endif ()
 else()
   add_lldb_executable(lldb-server
     lldb-gdbserver.cpp
     lldb-platform.cpp
     lldb-server.cpp
     LLDBServerUtilities.cpp
     ../../source/lldb.cpp
     )