[llvm-libgcc][CMake] Refactor llvm-libgcc (llvm#65455)

There are some issues in `llvm-libgcc` before this patch: Commit c5a20b5 ([llvm-libgcc] initial commit) uses `$<TARGET_OBJECTS:unwind_static>` to get libunwind objects, which is empty. The built library is actually a shared version of libclang_rt.builtins. When configuring with `llvm/CMakeLists.txt`, target `llvm-libgcc` requires a corresponding target in `llvm-libgcc/CMakeLists.txt`. Per target installation is not handled by `llvm-libgcc`, which is not consistent with `libunwind`. This patch fixes those issues by: Reusing target `unwind_shared` in `libunwind`, linking `compiler-rt.builtins` objects into it, and applying version script. Adding target `llvm-libgcc`, creating symlinks, and utilizing cmake's dependency and component mechanism to ensure link targets will be built and installed along with symlinks. Mimicking `libunwind` to handle per target installation. It is quite hard to set necessary options without further modifying the order of runtime projects in `runtimes/CMakeLists.txt`. So though this patch reveals the possibility of co-existence of `llvm-libgcc` and `compiler-rt`/`libunwind` in `LLVM_ENABLE_RUNTIMES`, we still inhibit it to minimize influence on other projects, considering that `llvm-libgcc` is only intended for toolchain vendors, and not for casual use.
adibiagio · Sep 19, 2023 · 7ac1f60 · 7ac1f60
1 parent 44532a9
commit 7ac1f60
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Showing 5 changed files with 134 additions and 122 deletions.
diff --git a/llvm-libgcc/CMakeLists.txt b/llvm-libgcc/CMakeLists.txt
@@ -1,19 +1,38 @@
-cmake_minimum_required(VERSION 3.20.0)
+#===============================================================================
+# Setup Project
+#===============================================================================
 
-if (NOT IS_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/../libunwind")
-  message(FATAL_ERROR "llvm-libgcc requires being built in a monorepo layout with libunwind available")
-endif()
+cmake_minimum_required(VERSION 3.20.0)
 
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
 
-list(APPEND CMAKE_MODULE_PATH
+# Check if llvm-libgcc is built as a standalone project
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LLVM_LIBGCC_STANDALONE_BUILD)
+  project(llvm-libgcc LANGUAGES C CXX ASM)
+  set(COMPILER_RT_STANDALONE_BUILD ON)
+  set_property(GLOBAL PROPERTY USE_FOLDERS ON)
+  set(LLVM_LIBGCC_COMPILER_RT_BINARY_DIR "compiler-rt")
+  set(LLVM_LIBGCC_LIBUNWIND_BINARY_DIR "libunwind")
+else()
+  set(LLVM_LIBGCC_COMPILER_RT_BINARY_DIR "../compiler-rt")
+  set(LLVM_LIBGCC_LIBUNWIND_BINARY_DIR "../libunwind")
+endif()
+
+# Add path for custom modules
+list(INSERT CMAKE_MODULE_PATH 0
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
+  "${CMAKE_CURRENT_SOURCE_DIR}/../runtimes/cmake/Modules"
   "${LLVM_COMMON_CMAKE_UTILS}"
   "${LLVM_COMMON_CMAKE_UTILS}/Modules"
-  )
+)
+
+set(LLVM_LIBGCC_LIBUNWIND_PATH "${CMAKE_CURRENT_LIST_DIR}/../libunwind"
+  CACHE PATH "Specify path to libunwind source.")
+set(LLVM_LIBGCC_COMPILER_RT_PATH "${CMAKE_CURRENT_LIST_DIR}/../compiler-rt"
+  CACHE PATH "Specify path to compiler-rt source.")
 
-project(llvm-libgcc LANGUAGES C CXX ASM)
+include(GNUInstallDirs)
 
 if(NOT LLVM_LIBGCC_EXPLICIT_OPT_IN)
   message(FATAL_ERROR
@@ -25,18 +44,114 @@ if(NOT LLVM_LIBGCC_EXPLICIT_OPT_IN)
     "to your CMake invocation and try again.")
 endif()
 
-set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib${LLVMLIB_DIR_SUFFIX}")
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib${LLVMLIB_DIR_SUFFIX}")
-set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/bin")
+if(HAVE_COMPILER_RT)
+  message(FATAL_ERROR
+    "Attempting to build both compiler-rt and llvm-libgcc will cause irreconcilable "
+    "target clashes. Please choose one or the other, but not both.")
+endif()
+
+if(HAVE_LIBUNWIND)
+  message(FATAL_ERROR
+    "Attempting to build both libunwind and llvm-libgcc will cause irreconcilable "
+    "target clashes. Please choose one or the other, but not both.")
+endif()
+
+#===============================================================================
+# Configure System
+#===============================================================================
+
+if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+  set(LLVM_LIBGCC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
+  set(LLVM_LIBGCC_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE} CACHE PATH
+      "Path where built llvm-libgcc libraries should be installed.")
+  if(LIBCXX_LIBDIR_SUBDIR)
+    string(APPEND LLVM_LIBGCC_LIBRARY_DIR /${LLVM_LIBGCC_LIBDIR_SUBDIR})
+    string(APPEND LLVM_LIBGCC_INSTALL_LIBRARY_DIR /${LLVM_LIBGCC_LIBDIR_SUBDIR})
+  endif()
+else()
+  if(LLVM_LIBRARY_OUTPUT_INTDIR)
+    set(LLVM_LIBGCC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
+  else()
+    set(LLVM_LIBGCC_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LLVM_LIBGCC_LIBDIR_SUFFIX})
+  endif()
+  set(LLVM_LIBGCC_INSTALL_LIBRARY_DIR lib${LLVM_LIBGCC_LIBDIR_SUFFIX} CACHE PATH
+      "Path where built llvm-libgcc libraries should be installed.")
+endif()
+
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LLVM_LIBGCC_LIBRARY_DIR})
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LLVM_LIBGCC_LIBRARY_DIR})
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LLVM_LIBGCC_LIBRARY_DIR})
+
+#===============================================================================
+# Build libraries
+#===============================================================================
+
+set(COMPILER_RT_BUILD_BUILTINS ON)
+set(COMPILER_RT_BUILTINS_HIDE_SYMBOLS OFF)
+add_subdirectory(${LLVM_LIBGCC_COMPILER_RT_PATH} ${LLVM_LIBGCC_COMPILER_RT_BINARY_DIR})
+
+set(LIBUNWIND_ENABLE_STATIC ON)
+set(LIBUNWIND_ENABLE_SHARED ON)
+set(LIBUNWIND_USE_COMPILER_RT OFF)
+set(LIBUNWIND_HAS_GCC_LIB OFF)
+set(LIBUNWIND_HAS_GCC_S_LIB OFF)
+add_subdirectory(${LLVM_LIBGCC_LIBUNWIND_PATH} ${LLVM_LIBGCC_LIBUNWIND_BINARY_DIR})
+
+add_custom_target(gcc_s.ver
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/gcc_s.ver.in
+  COMMAND ${CMAKE_C_COMPILER} -E
+    -xc ${CMAKE_CURRENT_SOURCE_DIR}/gcc_s.ver.in
+    -o ${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver
+)
+
+add_dependencies(unwind_shared gcc_s.ver)
+
+construct_compiler_rt_default_triple()
+
+target_link_options(unwind_shared PUBLIC
+  -Wl,--version-script,${CMAKE_CURRENT_BINARY_DIR}/gcc_s.ver
+)
+
+target_link_libraries(unwind_shared PUBLIC
+  $<TARGET_OBJECTS:clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}>
+  m
+)
+
+#===============================================================================
+# Install Symlinks
+#===============================================================================
+
+get_compiler_rt_install_dir(${COMPILER_RT_DEFAULT_TARGET_ARCH} install_dir_builtins)
+string(REGEX REPLACE "^lib/" "" install_dir_builtins "${install_dir_builtins}")
+string(FIND "${install_dir_builtins}" "clang" install_path_contains_triple)
+if(install_path_contains_triple EQUAL -1)
+  set(builtins_suffix "-${COMPILER_RT_DEFAULT_TARGET_ARCH}")
+else()
+  string(PREPEND install_dir_builtins "../")
+endif()
+set(LLVM_LIBGCC_COMPILER_RT ${install_dir_builtins}/libclang_rt.builtins${builtins_suffix}.a)
+
+add_custom_target(llvm-libgcc ALL
+  DEPENDS unwind_shared unwind_static clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}
+  COMMAND ${CMAKE_COMMAND} -E create_symlink ${LLVM_LIBGCC_COMPILER_RT} libgcc.a
+  COMMAND ${CMAKE_COMMAND} -E create_symlink libunwind.a libgcc_eh.a
+  COMMAND ${CMAKE_COMMAND} -E create_symlink libunwind.so libgcc_s.so.1.0
+  COMMAND ${CMAKE_COMMAND} -E create_symlink libgcc_s.so.1.0 libgcc_s.so.1
+  COMMAND ${CMAKE_COMMAND} -E create_symlink libgcc_s.so.1 libgcc_s.so
+)
 
-set(COMPILER_RT_BUILD_BUILTINS On)
-set(COMPILER_RT_BUILTINS_HIDE_SYMBOLS Off)
-add_subdirectory("../compiler-rt" "compiler-rt")
+install(TARGETS unwind_shared unwind_static
+  LIBRARY DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR} COMPONENT llvm-libgcc
+  ARCHIVE DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR} COMPONENT llvm-libgcc
+  RUNTIME DESTINATION ${LLVM_LIBGCC_INSTALL_RUNTIME_DIR} COMPONENT llvm-libgcc)
 
-set(LIBUNWIND_ENABLE_STATIC On)
-set(LIBUNWIND_ENABLE_SHARED Off)
-set(LIBUNWIND_HAS_COMMENT_LIB_PRAGMA Off)
-set(LIBUNWIND_USE_COMPILER_RT On)
-add_subdirectory("../libunwind" "libunwind")
+install(TARGETS clang_rt.builtins-${COMPILER_RT_DEFAULT_TARGET_ARCH}
+  LIBRARY DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc
+  ARCHIVE DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc
+  RUNTIME DESTINATION ${LLVM_LIBGCC_INSTALL_RUNTIME_DIR}/${install_dir_builtins} COMPONENT llvm-libgcc)
 
-add_subdirectory(lib)
+foreach(VAR libgcc.a libgcc_eh.a libgcc_s.so.1.0 libgcc_s.so.1 libgcc_s.so)
+  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${VAR}
+    DESTINATION ${LLVM_LIBGCC_INSTALL_LIBRARY_DIR}
+    COMPONENT llvm-libgcc)
+endforeach()
diff --git a/llvm-libgcc/lib/gcc_s.ver → llvm-libgcc/gcc_s.ver.in b/llvm-libgcc/lib/gcc_s.ver → llvm-libgcc/gcc_s.ver.in
diff --git a/llvm-libgcc/lib/CMakeLists.txt b/llvm-libgcc/lib/CMakeLists.txt
diff --git a/llvm-libgcc/lib/blank.c b/llvm-libgcc/lib/blank.c
diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
@@ -216,23 +216,6 @@ if(LLVM_INCLUDE_TESTS)
   umbrella_lit_testsuite_begin(check-runtimes)
 endif()
 
-# llvm-libgcc incorporates both compiler-rt and libunwind as subprojects with very
-# specific flags, which causes clashes when they're independently built too.
-if("llvm-libgcc" IN_LIST runtimes)
-  if("compiler-rt" IN_LIST runtimes OR "compiler-rt" IN_LIST LLVM_ENABLE_PROJECTS)
-    message(FATAL_ERROR
-      "Attempting to build both compiler-rt and llvm-libgcc will cause irreconcilable "
-      "target clashes. Please choose one or the other, but not both.")
-  endif()
-
-  if("libunwind" IN_LIST runtimes)
-    message(
-      FATAL_ERROR
-      "Attempting to build both libunwind and llvm-libgcc will cause irreconcilable "
-      "target clashes. Please choose one or the other, but not both.")
-  endif()
-endif()
-
 # We do this in two loops so that HAVE_* is set for each runtime before the
 # other runtimes are added.
 foreach(entry ${runtimes})