Compute Python library suffix in CMakeLists.txt

Introduce LLDB_PY_LIB_SUFFIX and use it in various places in the
build.  This lets the x.py-based build work properly without having to
set LLVM_LIBDIR_SUFFIX.

See https://bugs.llvm.org/show_bug.cgi?id=18957 for some discussion.

Author: tromey

lldb/CMakeLists.txt

@@ -28,6 +28,13 @@ if(APPLE)
   add_definitions(-DLLDB_USE_OS_LOG)
 endif()
 
+if (NOT LLDB_DISABLE_PYTHON)
+   execute_process(
+     COMMAND
+        ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/scripts/get_libdir_suffix.py
+     OUTPUT_VARIABLE LLDB_PY_LIB_SUFFIX)
+endif ()
+
 add_subdirectory(docs)
 if (NOT LLDB_DISABLE_PYTHON)
   add_subdirectory(scripts)
@@ -146,7 +153,7 @@ if (NOT LLDB_DISABLE_PYTHON)
                --cfgBldDir=${lldb_scripts_dir}
                --prefix=${CMAKE_BINARY_DIR}
                --cmakeBuildConfiguration=${CMAKE_CFG_INTDIR}
-               --lldbLibDir=lib${LLVM_LIBDIR_SUFFIX}
+               --lldbLibDir=lib${LLDB_PY_LIB_SUFFIX}
                ${use_python_wrapper_from_src_dir}
                ${use_six_py_from_system}
         VERBATIM

lldb/docs/CMakeLists.txt

@@ -35,7 +35,7 @@ if(EPYDOC_EXECUTABLE)
       --url "http://lldb.llvm.org"
       ${EPYDOC_OPTIONS}
       DEPENDS swig_wrapper liblldb
-      WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/../../../lib${LLVM_LIBDIR_SUFFIX}/python2.7/site-packages
+      WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/../../../lib${LLDB_PY_LIB_SUFFIX}/python2.7/site-packages
       COMMENT "Generating LLDB Python API reference with epydoc" VERBATIM
     )
 endif(EPYDOC_EXECUTABLE)

lldb/scripts/CMakeLists.txt

@@ -47,7 +47,7 @@ if(NOT LLDB_BUILD_FRAMEWORK)
   endif()
 
   set(SWIG_PYTHON_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${swig_python_subdir})
-  set(SWIG_INSTALL_DIR lib${LLVM_LIBDIR_SUFFIX})
+  set(SWIG_INSTALL_DIR lib${LLDB_PY_LIB_SUFFIX})
 
   # Install the LLDB python module
   install(DIRECTORY ${SWIG_PYTHON_DIR} DESTINATION ${SWIG_INSTALL_DIR})

lldb/scripts/Python/modules/readline/CMakeLists.txt

@@ -24,4 +24,4 @@ set_target_properties(readline PROPERTIES
                                LIBRARY_OUTPUT_PATH ${CMAKE_CURRENT_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/${PYTHON_DIRECTORY})
 
 # Install the readline module.
-install(TARGETS readline LIBRARY DESTINATION ${CMAKE_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}/${PYTHON_DIRECTORY})
+install(TARGETS readline LIBRARY DESTINATION ${CMAKE_INSTALL_PREFIX}/lib${LLDB_PY_LIB_SUFFIX}/${PYTHON_DIRECTORY})

lldb/scripts/get_libdir_suffix.py

@@ -0,0 +1,33 @@
+import distutils.sysconfig
+import os
+import platform
+import re
+import sys
+
+
+def get_python_libdir_suffix():
+    """Returns the appropropriate python libdir suffix.
+
+    @return the python libdir suffix, normally either "" or "64".
+    """
+    if platform.system() != 'Linux':
+        return ""
+
+    # We currently have a bug in lldb -P that does not account for
+    # architecture variants in python paths for
+    # architecture-specific modules.  Handle the lookup here.
+    # When that bug is fixed, we should just ask lldb for the
+    # right answer always.
+    arch_specific_libdir = distutils.sysconfig.get_python_lib(True, False)
+    split_libdir = arch_specific_libdir.split(os.sep)
+    lib_re = re.compile(r"^lib.+$")
+
+    for i in range(len(split_libdir)):
+        match = lib_re.match(split_libdir[i])
+        if match is not None:
+            return split_libdir[i][3:]
+    return ""
+
+if __name__ == '__main__':
+    sys.stdout.write(get_python_libdir_suffix())
+    sys.exit(0)