[cmake] Split linked libraries into private & public, for linker script

Introduce LIBCXX_LIBRARIES_PUBLIC in addition to LIBCXX_LIBRARIES that
holds 'public' interface libraries -- that is, libraries that both
libc++ links to and programs linked against it need to link to.

Currently this includes the ABI library and optionally -lunwind (when
LIBCXXABI_USE_LLVM_UNWINDER is on). The libraries are included in the
linker script, in order to make it possible to link C++ programs using
clang with compiler-rt runtime out-of-the-box.

Differential Revision: https://reviews.llvm.org/D25008

llvm-svn: 283659

libcxx/CMakeLists.txt

@@ -270,9 +270,13 @@ set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBCXX_LIBRARY_DIR})
 # LIBCXX_CXX_FLAGS: General flags for both the compiler and linker.
 # LIBCXX_COMPILE_FLAGS: Compile only flags.
 # LIBCXX_LINK_FLAGS: Linker only flags.
+# LIBCXX_LIBRARIES: Private libraries libc++ is linked to.
+# LIBCXX_LIBRARIES_PUBLIC: Public libraries libc++ is linked to,
+#                          also exposed in the linker script.
 set(LIBCXX_COMPILE_FLAGS "")
 set(LIBCXX_LINK_FLAGS "")
 set(LIBCXX_LIBRARIES "")
+set(LIBCXX_LIBRARIES_PUBLIC "")
 
 # Include macros for adding and removing libc++ flags.
 include(HandleLibcxxFlags)

libcxx/lib/CMakeLists.txt

@@ -33,9 +33,17 @@ add_link_flags_if(LIBCXX_CXX_ABI_LIBRARY_PATH "-L${LIBCXX_CXX_ABI_LIBRARY_PATH}"
 
 add_library_flags_if(LIBCXX_COVERAGE_LIBRARY "${LIBCXX_COVERAGE_LIBRARY}")
 
-add_library_flags_if(LIBCXX_ENABLE_STATIC_ABI_LIBRARY "-Wl,--whole-archive" "-Wl,-Bstatic")
+if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
-add_library_flags("${LIBCXX_CXX_ABI_LIBRARY}")
+  add_library_flags("-Wl,--whole-archive" "-Wl,-Bstatic")
-add_library_flags_if(LIBCXX_ENABLE_STATIC_ABI_LIBRARY "-Wl,-Bdynamic" "-Wl,--no-whole-archive")
+  add_library_flags("${LIBCXX_CXX_ABI_LIBRARY}")
+  add_library_flags("-Wl,-Bdynamic" "-Wl,--no-whole-archive")
+elseif (APPLE AND (LIBCXX_CXX_ABI_LIBNAME STREQUAL "libcxxabi" OR
+                   LIBCXX_CXX_ABI_LIBNAME STREQUAL "none"))
+  # Apple re-exports libc++abi in libc++, so don't make it public
+  add_library_flags("${LIBCXX_CXX_ABI_LIBRARY}")
+else()
+  list(APPEND LIBCXX_LIBRARIES_PUBLIC "${LIBCXX_CXX_ABI_LIBRARY}")
+endif()
 
 if (APPLE AND LLVM_USE_SANITIZER)
   if (("${LLVM_USE_SANITIZER}" STREQUAL "Address") OR
@@ -67,7 +75,7 @@ if (APPLE AND LLVM_USE_SANITIZER)
   endif()
 endif()
 
-# Generate library list.
+# Generate private library list.
 add_library_flags_if(LIBCXX_HAS_PTHREAD_LIB pthread)
 add_library_flags_if(LIBCXX_HAS_C_LIB c)
 add_library_flags_if(LIBCXX_HAS_M_LIB m)
@@ -75,6 +83,11 @@ add_library_flags_if(LIBCXX_HAS_RT_LIB rt)
 add_library_flags_if(LIBCXX_HAS_GCC_S_LIB gcc_s)
 add_library_flags_if(LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB atomic)
 
+# Add the unwinder library.
+if (LIBCXXABI_USE_LLVM_UNWINDER)
+  list(APPEND LIBCXX_LIBRARIES_PUBLIC unwind)
+endif()
+
 # Setup flags.
 if (NOT WIN32)
   add_flags_if_supported(-fPIC)
@@ -151,7 +164,9 @@ set(LIBCXX_TARGETS)
 # Build the shared library.
 if (LIBCXX_ENABLE_SHARED)
   add_library(cxx_shared SHARED $<TARGET_OBJECTS:cxx_objects>)
-  target_link_libraries(cxx_shared ${LIBCXX_LIBRARIES})
+  target_link_libraries(cxx_shared
+    PRIVATE ${LIBCXX_LIBRARIES}
+    PUBLIC ${LIBCXX_LIBRARIES_PUBLIC})
   set_target_properties(cxx_shared
     PROPERTIES
       LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
@@ -165,7 +180,9 @@ endif()
 # Build the static library.
 if (LIBCXX_ENABLE_STATIC)
   add_library(cxx_static STATIC $<TARGET_OBJECTS:cxx_objects>)
-  target_link_libraries(cxx_static ${LIBCXX_LIBRARIES})
+  target_link_libraries(cxx_static
+    PRIVATE ${LIBCXX_LIBRARIES}
+    PUBLIC ${LIBCXX_LIBRARIES_PUBLIC})
   set_target_properties(cxx_static
     PROPERTIES
       LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
@@ -238,7 +255,7 @@ if (LIBCXX_ENABLE_SHARED AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
       ${PYTHON_EXECUTABLE} ${LIBCXX_SOURCE_DIR}/utils/gen_link_script/gen_link_script.py
     ARGS
       "$<TARGET_LINKER_FILE:cxx_shared>"
-      "${SCRIPT_ABI_LIBNAME}"
+      "\"${LIBCXX_LIBRARIES_PUBLIC}\""
     WORKING_DIRECTORY ${LIBCXX_BUILD_DIR}
   )
 endif()

libcxx/utils/gen_link_script/gen_link_script.py

@@ -22,7 +22,7 @@ def help_and_exit():
     help_msg = \
 """Usage
 
-  gen_link_script.py [--help] [--dryrun] <path/to/libcxx.so> <abi_libname>
+  gen_link_script.py [--help] [--dryrun] <path/to/libcxx.so> <public_libs>
 
   Generate a linker script that links libc++ to the proper ABI library.
   The script replaces the specified libc++ symlink.
@@ -31,8 +31,7 @@ def help_and_exit():
 Arguments
   <path/to/libcxx.so> - The top level symlink to the versioned libc++ shared
                         library. This file is replaced with a linker script.
-  <abi_libname>       - The name of the ABI library to use in the linker script.
+  <public_libs>       - List of library names to include in linker script.
-                        The name must be one of [c++abi, stdc++, supc++, cxxrt].
 
 Exit Status:
   0 if OK,
@@ -53,11 +52,11 @@ def parse_args():
     if len(args) != 2:
         usage_and_exit()
     symlink_file = args[0]
-    abi_libname = args[1]
+    public_libs = args[1].split(';')
-    return dryrun, symlink_file, abi_libname
+    return dryrun, symlink_file, public_libs
 
 def main():
-    dryrun, symlink_file, abi_libname = parse_args()
+    dryrun, symlink_file, public_libs = parse_args()
 
     # Check that the given libc++.so file is a valid symlink.
     if not os.path.islink(symlink_file):
@@ -66,15 +65,12 @@ def main():
     # Read the symlink so we know what libc++ to link to in the linker script.
     linked_libcxx = os.readlink(symlink_file)
 
-    # Check that the abi_libname is one of the supported values.
+    # Prepare the list of public libraries to link.
-    supported_abi_list = ['c++abi', 'stdc++', 'supc++', 'cxxrt']
+    public_libs = ['-l%s' % l for l in public_libs]
-    if abi_libname not in supported_abi_list:
-        print_and_exit("abi name '%s' is not supported: Use one of %r" %
-                        (abi_libname, supported_abi_list))
 
     # Generate the linker script contents and print the script and destination
     # information.
-    contents = "INPUT(%s -l%s)" % (linked_libcxx, abi_libname)
+    contents = "INPUT(%s %s)" % (linked_libcxx, ' '.join(public_libs))
     print("GENERATING SCRIPT: '%s' as file %s" % (contents, symlink_file))
 
     # Remove the existing libc++ symlink and replace it with the script.