[runtimes] Fix the build of merged ABI/unwinder libraries

[ldionne]

Summary

Also, add a CI job that tests this configuration. The exact configuration
is that we build a shared libc++ and merge objects for the ABI library
and the unwinder library into it.

[ldionne]

Seems like this fixes the issue that was reported by user kristina_ on Discord, and it fixes the issues I was seeing locally. I'll ship this once CI is green.

[kristina]

Thank you, build is fine after applying the patch.

[phosek]

LGTM

libcxx/CMakeLists.txt

 endif()
 
 option(LIBCXX_ENABLE_STATIC_ABI_LIBRARY
   "Use a static copy of the ABI library when linking libc++.
    This option cannot be used with LIBCXX_ENABLE_ABI_LINKER_SCRIPT." OFF)
 
 cmake_dependent_option(LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY
   "Statically link the ABI library to static library" ON
-  "LIBCXX_ENABLE_STATIC_ABI_LIBRARY;LIBCXX_ENABLE_STATIC" OFF)
+  "LIBCXX_ENABLE_STATIC_ABI_LIBRARY" OFF)
 
 cmake_dependent_option(LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY
   "Statically link the ABI library to shared library" ON
-  "LIBCXX_ENABLE_STATIC_ABI_LIBRARY;LIBCXX_ENABLE_SHARED" OFF)
+  "LIBCXX_ENABLE_STATIC_ABI_LIBRARY" OFF)
 
 # Generate and install a linker script inplace of libc++.so. The linker script
 # will link libc++ to the correct ABI library. This option is on by default
 # on UNIX platforms other than Apple unless 'LIBCXX_ENABLE_STATIC_ABI_LIBRARY'
 # is on. This option is also disabled when the ABI library is not specified
 # or is specified to be "none".
 set(ENABLE_LINKER_SCRIPT_DEFAULT_VALUE OFF)
 if (LLVM_HAVE_LINK_VERSION_SCRIPT AND NOT LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY

libcxx/cmake/caches/Generic-merged.cmake

+# Build a libc++ shared library, but merge libc++abi and libunwind into it.
+set(LIBCXX_ENABLE_SHARED ON CACHE BOOL "")
+set(LIBCXX_ENABLE_ABI_LINKER_SCRIPT OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
+set(LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY ON CACHE BOOL "")
+
+set(LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
+set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
+set(LIBCXXABI_ENABLE_STATIC_UNWINDER ON CACHE BOOL "")
+set(LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY ON CACHE BOOL "")
+
+set(LIBUNWIND_ENABLE_SHARED OFF CACHE BOOL "")

libcxx/src/CMakeLists.txt

if (LIBCXX_ENABLE_SHARED)
   cxx_add_common_build_flags(cxx_shared)
   cxx_set_common_defines(cxx_shared)
 
   # Link against LLVM libunwind
   # Note that we do need to link against libunwind directly to ensure that the correct
   # dependencies are recorded when creating a linker script.
   # TODO: Look into modifying the linker script creation to recursively consider interface libraries
   if (LIBCXXABI_USE_LLVM_UNWINDER)
-    if (NOT LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY AND (TARGET unwind_shared OR HAVE_LIBUNWIND))
-      target_link_libraries(cxx_shared PUBLIC unwind_shared)
-    elseif (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY AND (TARGET unwind_static OR HAVE_LIBUNWIND))
+    if (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY)
       # libunwind is already included in libc++abi
+    elseif (TARGET unwind_shared OR HAVE_LIBUNWIND)
+      target_link_libraries(cxx_shared PUBLIC unwind_shared)
     else()
       target_link_libraries(cxx_shared PUBLIC unwind)
     endif()
   endif()
 
   # Link against libc++abi
   if (LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
     target_link_libraries(cxx_shared PRIVATE libcxx-abi-shared-objects)

libcxx/utils/ci/buildkite-pipeline.yml

agents:
       queue: "libcxx-builders"
       os: "linux"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
           limit: 2
     timeout_in_minutes: 120
 
+  - label: "Shared library with merged ABI and unwinder libraries"
+    command: "libcxx/utils/ci/run-buildbot generic-merged"
+    artifact_paths:
+      - "**/test-results.xml"
+      - "**/*.abilist"
+    agents:
+      queue: "libcxx-builders"
+      os: "linux"
+    retry:
+      automatic:
+        - exit_status: -1  # Agent was lost
+          limit: 2
+    timeout_in_minutes: 120
+
   - label: "Assertions enabled"
     command: "libcxx/utils/ci/run-buildbot generic-assertions"
     artifact_paths:
       - "**/test-results.xml"
       - "**/*.abilist"
     agents:
       queue: "libcxx-builders"
       os: "linux"

libcxx/utils/ci/run-buildbot

generic-modules)
     check-abi-list
 ;;
 generic-static)
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-static.cmake" \
                    -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-static.cfg.in"
     check-runtimes
 ;;
+generic-merged)
+    clean
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-merged.cmake" \
+                   -DLIBCXX_TEST_CONFIG="llvm-libc++-shared.cfg.in" \
+                   -DLIBCXXABI_TEST_CONFIG="llvm-libc++abi-merged.cfg.in" \
+                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-merged.cfg.in"
+    check-runtimes
+;;
 generic-clang-13)
     export CC=clang-13
     export CXX=clang++-13
     clean
     generate-cmake -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
     check-runtimes
     check-abi-list
 ;;

libcxxabi/CMakeLists.txt

cmake_dependent_option(LIBCXXABI_INSTALL_STATIC_LIBRARY
   "Install the static libc++abi library." ON
   "LIBCXXABI_ENABLE_STATIC;LIBCXXABI_INSTALL_LIBRARY" OFF)
 cmake_dependent_option(LIBCXXABI_INSTALL_SHARED_LIBRARY
   "Install the shared libc++abi library." ON
   "LIBCXXABI_ENABLE_SHARED;LIBCXXABI_INSTALL_LIBRARY" OFF)
 
 cmake_dependent_option(LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY
   "Statically link the LLVM unwinder to static library" ON
-  "LIBCXXABI_ENABLE_STATIC_UNWINDER;LIBCXXABI_ENABLE_STATIC" OFF)
+  "LIBCXXABI_ENABLE_STATIC_UNWINDER" OFF)
 cmake_dependent_option(LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY
   "Statically link the LLVM unwinder to shared library" ON
-  "LIBCXXABI_ENABLE_STATIC_UNWINDER;LIBCXXABI_ENABLE_SHARED" OFF)
+  "LIBCXXABI_ENABLE_STATIC_UNWINDER" OFF)
 
 option(LIBCXXABI_BAREMETAL "Build libc++abi for baremetal targets." OFF)
 # The default terminate handler attempts to demangle uncaught exceptions, which
 # causes extra I/O and demangling code to be pulled in.
 option(LIBCXXABI_SILENT_TERMINATE "Set this to make the terminate handler default to a silent alternative" OFF)
 option(LIBCXXABI_NON_DEMANGLING_TERMINATE "Set this to make the terminate handler
 avoid demangling" OFF)
 

libcxxabi/src/CMakeLists.txt

 if (NOT TARGET pstl::ParallelSTL)
   message(STATUS "Could not find ParallelSTL, libc++abi will not attempt to use it but the build may fail if the libc++ in use needs it to be available.")
 endif()
 
 # Build the shared library.
 add_library(cxxabi_shared_objects OBJECT EXCLUDE_FROM_ALL ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
 if (LIBCXXABI_USE_LLVM_UNWINDER)
   if (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY)
+    target_link_libraries(cxxabi_shared_objects PUBLIC unwind_shared_objects) # propagate usage requirements
     target_sources(cxxabi_shared_objects PUBLIC $<TARGET_OBJECTS:unwind_shared_objects>)
   else()
     target_link_libraries(cxxabi_shared_objects PUBLIC unwind_shared)
   endif()
 endif()
 target_link_libraries(cxxabi_shared_objects PRIVATE cxx-headers ${LIBCXXABI_BUILTINS_LIBRARY} ${LIBCXXABI_SHARED_LIBRARIES} ${LIBCXXABI_LIBRARIES})
 target_link_libraries(cxxabi_shared_objects PUBLIC cxxabi-headers)
 set_target_properties(cxxabi_shared_objects
if (LIBCXXABI_ENABLE_EXCEPTIONS)
       endif()
     endif()
   endif()
 endif()
 
 # Build the static library.
 add_library(cxxabi_static_objects OBJECT EXCLUDE_FROM_ALL ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
 if (LIBCXXABI_USE_LLVM_UNWINDER AND LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY)
+  target_link_libraries(cxxabi_static_objects PUBLIC unwind_static_objects) # propagate usage requirements
   target_sources(cxxabi_static_objects PUBLIC $<TARGET_OBJECTS:unwind_static_objects>)
 endif()
 target_link_libraries(cxxabi_static_objects PRIVATE cxx-headers ${LIBCXXABI_STATIC_LIBRARIES} ${LIBCXXABI_LIBRARIES})
 target_link_libraries(cxxabi_static_objects PUBLIC cxxabi-headers)
 set_target_properties(cxxabi_static_objects
   PROPERTIES
     CXX_EXTENSIONS OFF
     CXX_STANDARD 20

libcxxabi/test/configs/llvm-libc++abi-merged.cfg.in

+# Testing configuration for libc++abi when merged into a libc++ shared library.
+
+lit_config.load_config(config, '@CMAKE_CURRENT_BINARY_DIR@/cmake-bridge.cfg')
+
+config.substitutions.append(('%{flags}',
+    '-isysroot {}'.format('@CMAKE_OSX_SYSROOT@') if '@CMAKE_OSX_SYSROOT@' else ''
+))
+config.substitutions.append(('%{compile_flags}',
+    '-nostdinc++ -I %{include} -I %{cxx-include} -I %{cxx-target-include} -DLIBCXXABI_NO_TIMER -D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS ' +
+    '-I %{libcxx}/test/support -I %{libcxx}/src'
+))
+config.substitutions.append(('%{link_flags}',
+    '-nostdlib++ -L %{lib} -Wl,-rpath,%{lib} -lc++ -pthread'
+))
+config.substitutions.append(('%{exec}',
+    '%{executor} --execdir %T -- '
+))
+
+import os, site
+site.addsitedir(os.path.join('@LIBCXXABI_LIBCXX_PATH@', 'utils'))
+import libcxx.test.params, libcxx.test.newconfig, libcxx.test.newconfig
+libcxx.test.newconfig.configure(
+    libcxx.test.params.DEFAULT_PARAMETERS,
+    libcxx.test.features.DEFAULT_FEATURES,
+    config,
+    lit_config
+)

libunwind/test/configs/llvm-libunwind-merged.cfg.in

+@AUTO_GEN_COMMENT@
+
+@SERIALIZED_LIT_PARAMS@
+
+#
+# Configuration file for running the libunwind tests against a libc++ shared library
+# into which the unwinder was merged.
+#
+
+import os, site
+site.addsitedir(os.path.join('@LIBUNWIND_LIBCXX_PATH@', 'utils'))
+import libcxx.test.format
+
+# Basic configuration of the test suite
+config.name = os.path.basename('@LIBUNWIND_TEST_CONFIG@')
+config.test_source_root = os.path.join('@LIBUNWIND_SOURCE_DIR@', 'test')
+config.test_format = libcxx.test.format.CxxStandardLibraryTest()
+config.recursiveExpansionLimit = 10
+config.test_exec_root = '@CMAKE_BINARY_DIR@'
+config.target_info = "@LIBUNWIND_TARGET_INFO@"
+
+compile_flags = []
+link_flags = []
+if @LIBUNWIND_USES_ARM_EHABI@:
+    config.available_features.add('libunwind-arm-ehabi')
+
+if not @LIBUNWIND_ENABLE_THREADS@:
+    compile_flags.append('-D_LIBUNWIND_HAS_NO_THREADS')
+    config.available_features.add('libunwind-no-threads')
+
+if @LIBUNWIND_ENABLE_CET@:
+    compile_flags.append('-fcf-protection=full')
+
+if '@CMAKE_SYSTEM_NAME@' == 'Linux':
+    link_flags.append('-Wl,--export-dynamic')
+
+# Stack unwinding tests need unwinding tables and these are not generated by default on all targets.
+compile_flags.append('-funwind-tables')
+
+config.substitutions.append(('%{executor}', '@LIBUNWIND_EXECUTOR@'))
+
+config.substitutions.append(('%{cxx}', '@CMAKE_CXX_COMPILER@'))
+local_sysroot = '@CMAKE_OSX_SYSROOT@' or '@CMAKE_SYSROOT@'
+config.substitutions.append(('%{flags}',
+    '-isysroot {}'.format(local_sysroot) if local_sysroot else ''
+))
+config.substitutions.append(('%{compile_flags}',
+    '-nostdinc++ -I {}/include {}'.format('@LIBUNWIND_SOURCE_DIR@', ' '.join(compile_flags))
+))
+config.substitutions.append(('%{link_flags}',
+    '-L {0} -Wl,-rpath,{0} -lc++ -ldl {1}'.format('@LIBUNWIND_LIBRARY_DIR@', ' '.join(link_flags))
+))
+config.substitutions.append(('%{exec}',
+    '%{executor} --execdir %T -- ' if '@LIBUNWIND_EXECUTOR@' else ''
+))
+
+import os, site
+site.addsitedir(os.path.join('@LIBUNWIND_LIBCXX_PATH@', 'utils'))
+import libcxx.test.params, libcxx.test.newconfig, libcxx.test.newconfig
+libcxx.test.newconfig.configure(
+    libcxx.test.params.DEFAULT_PARAMETERS,
+    libcxx.test.features.DEFAULT_FEATURES,
+    config,
+    lit_config
+)