Fix DynamicLibraryTests build on Windows when LLVM_EXPORT_SYMBOLS_FOR_PLUGINS is ON

[michaelplatings]

Summary

extract_symbols.py (introduced in D18826) expects all of its library arguments to be in the same directory - typically <config>/lib. DynamicLibraryLib.lib is instead to be found in lib/<config>.
This patch passes locations of libraries directly to extract_symbols.py so it doesn't need to guess.

[rnk]

lgtm

[michaelplatings]

Thanks very much Reid for the speedy review. Unfortunately, due the the use of absolute paths, this patch causes long command lines to be generated which Visual Studio 2015 can't handle. So I have to abandon this patch.

llvm/cmake/modules/AddLLVM.cmake

elseif (LLVM_EXPORT_SYMBOLS_FOR_PLUGINS)
     get_target_property(new_libs ${target} LINK_LIBRARIES)
     set(link_libs ${new_libs})
     while(NOT "${new_libs}" STREQUAL "")
       foreach(lib ${new_libs})
         if(TARGET ${lib})
           get_target_property(lib_type ${lib} TYPE)
           if("${lib_type}" STREQUAL "STATIC_LIBRARY")
             list(APPEND static_libs ${lib})
+            list(APPEND static_lib_files $<TARGET_LINKER_FILE:${lib}>)
           else()
             list(APPEND other_libs ${lib})
           endif()
           get_target_property(transitive_libs ${lib} INTERFACE_LINK_LIBRARIES)
           foreach(transitive_lib ${transitive_libs})
             list(FIND link_libs ${transitive_lib} idx)
             if(TARGET ${transitive_lib} AND idx EQUAL -1)
               list(APPEND newer_libs ${transitive_lib})
               list(APPEND link_libs ${transitive_lib})
             endif()
           endforeach(transitive_lib)
         endif()
       endforeach(lib)
       set(new_libs ${newer_libs})
       set(newer_libs "")
     endwhile()
     if (MSVC)
       set(mangling microsoft)
     else()
       set(mangling itanium)
     endif()
     add_custom_command(OUTPUT ${exported_symbol_file}
-                       COMMAND ${PYTHON_EXECUTABLE} ${LLVM_MAIN_SRC_DIR}/utils/extract_symbols.py --mangling=${mangling} ${static_libs} -o ${exported_symbol_file}
+                       COMMAND ${PYTHON_EXECUTABLE} ${LLVM_MAIN_SRC_DIR}/utils/extract_symbols.py --mangling=${mangling} ${static_lib_files} -o ${exported_symbol_file}
                        WORKING_DIRECTORY ${LLVM_LIBRARY_OUTPUT_INTDIR}
                        DEPENDS ${LLVM_MAIN_SRC_DIR}/utils/extract_symbols.py ${static_libs}
                        VERBATIM
                        COMMENT "Generating export list for ${target}")
     add_llvm_symbol_exports( ${target} ${exported_symbol_file} )
     # If something links against this executable then we want a
     # transitive link against only the libraries whose symbols
     # we aren't exporting.

llvm/utils/extract_symbols.py

if __name__ == '__main__':
     if args.mangling == 'microsoft':
         should_keep_symbol = should_keep_microsoft_symbol
     else:
         should_keep_symbol = should_keep_itanium_symbol
 
     # Get the list of libraries to extract symbols from
     libs = list()
     for lib in args.libs:
-        # When invoked by cmake the arguments are the cmake target names of the
-        # libraries, so we need to add .lib/.a to the end and maybe lib to the
-        # start to get the filename. Also allow objects.
-        suffixes = ['.lib','.a','.obj','.o']
-        if not any([lib.endswith(s) for s in suffixes]):
-            for s in suffixes:
-                if os.path.exists(lib+s):
-                    lib = lib+s
-                    break
-                if os.path.exists('lib'+lib+s):
-                    lib = 'lib'+lib+s
-                    break
-        if not any([lib.endswith(s) for s in suffixes]):
+        if not os.path.exists(lib):
             print("Don't know what to do with argument "+lib, file=sys.stderr)
             exit(1)
         libs.append(lib)
 
     # Check if calling convention decoration is used by inspecting the first
     # library in the list
     calling_convention_decoration = is_32bit_windows(libs[0])