[runtimes] Introduce object libraries

This is a variant of D116689 rebased on top of the new (proposed) ABI
refactoring in D120727. It should conserve the basic properties of the
original patch by @phosek, except it also allows cleaning up the merging
of libc++abi into libc++ from the libc++ side.

Differential Revision: https://reviews.llvm.org/D125393

1 files changed, 44 insertions, 31 deletions

diff --git a/libunwind/src/CMakeLists.txt b/libunwind/src/CMakeLists.txt
index faef6a8..61df273 100644
--- a/libunwind/src/CMakeLists.txt
+++ b/libunwind/src/CMakeLists.txt
@@ -136,27 +136,36 @@ set_property(SOURCE ${LIBUNWIND_C_SOURCES}
 set(CMAKE_CXX_IMPLICIT_LINK_LIBRARIES "")
 
 # Build the shared library.
+add_library(unwind_shared_objects OBJECT EXCLUDE_FROM_ALL ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
+if(CMAKE_C_COMPILER_ID STREQUAL MSVC)
+  target_compile_options(unwind_shared_objects PRIVATE /GR-)
+else()
+  target_compile_options(unwind_shared_objects PRIVATE -fno-rtti)
+endif()
+target_link_libraries(unwind_shared_objects PRIVATE unwind-headers ${LIBUNWIND_LIBRARIES})
+set_target_properties(unwind_shared_objects
+  PROPERTIES
+    CXX_EXTENSIONS OFF
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED ON
+    COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
+)
+if (CMAKE_POSITION_INDEPENDENT_CODE OR NOT DEFINED CMAKE_POSITION_INDEPENDENT_CODE)
+  set_target_properties(unwind_shared_objects PROPERTIES POSITION_INDEPENDENT_CODE ON) # must set manually because it's an object library
+endif()
+
 if (LIBUNWIND_ENABLE_SHARED)
-  add_library(unwind_shared SHARED ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
-  if(CMAKE_C_COMPILER_ID STREQUAL MSVC)
-    target_compile_options(unwind_shared PRIVATE /GR-)
-  else()
-    target_compile_options(unwind_shared PRIVATE -fno-rtti)
-  endif()
-  target_link_libraries(unwind_shared PRIVATE ${LIBUNWIND_LIBRARIES}
-                                      PRIVATE unwind-headers)
+  add_library(unwind_shared SHARED)
+  target_link_libraries(unwind_shared PUBLIC unwind_shared_objects)
   set_target_properties(unwind_shared
     PROPERTIES
-      CXX_EXTENSIONS OFF
-      CXX_STANDARD 11
-      CXX_STANDARD_REQUIRED ON
-      COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
       LINK_FLAGS "${LIBUNWIND_LINK_FLAGS}"
       LINKER_LANGUAGE C
       OUTPUT_NAME "unwind"
       VERSION "1.0"
       SOVERSION "1"
   )
+
   list(APPEND LIBUNWIND_BUILD_TARGETS "unwind_shared")
   if (LIBUNWIND_INSTALL_SHARED_LIBRARY)
     list(APPEND LIBUNWIND_INSTALL_TARGETS "unwind_shared")
@@ -164,33 +173,37 @@ if (LIBUNWIND_ENABLE_SHARED)
 endif()
 
 # Build the static library.
+add_library(unwind_static_objects OBJECT EXCLUDE_FROM_ALL ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
+if(CMAKE_C_COMPILER_ID STREQUAL MSVC)
+  target_compile_options(unwind_static_objects PRIVATE /GR-)
+else()
+  target_compile_options(unwind_static_objects PRIVATE -fno-rtti)
+endif()
+target_link_libraries(unwind_static_objects PRIVATE unwind-headers ${LIBUNWIND_LIBRARIES})
+set_target_properties(unwind_static_objects
+  PROPERTIES
+    CXX_EXTENSIONS OFF
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED ON
+    COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
+)
+
+if(LIBUNWIND_HIDE_SYMBOLS)
+  target_add_compile_flags_if_supported(unwind_static_objects PRIVATE -fvisibility=hidden)
+  target_add_compile_flags_if_supported(unwind_static_objects PRIVATE -fvisibility-global-new-delete-hidden)
+  target_compile_definitions(unwind_static_objects PRIVATE _LIBUNWIND_HIDE_SYMBOLS)
+endif()
+
 if (LIBUNWIND_ENABLE_STATIC)
-  add_library(unwind_static STATIC ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
-  if(CMAKE_C_COMPILER_ID STREQUAL MSVC)
-    target_compile_options(unwind_static PRIVATE /GR-)
-  else()
-    target_compile_options(unwind_static PRIVATE -fno-rtti)
-  endif()
-  target_link_libraries(unwind_static PRIVATE ${LIBUNWIND_LIBRARIES}
-                                      PRIVATE unwind-headers)
+  add_library(unwind_static STATIC)
+  target_link_libraries(unwind_static PUBLIC unwind_static_objects)
   set_target_properties(unwind_static
     PROPERTIES
-      CXX_EXTENSIONS OFF
-      CXX_STANDARD 11
-      CXX_STANDARD_REQUIRED ON
-      COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
       LINK_FLAGS "${LIBUNWIND_LINK_FLAGS}"
       LINKER_LANGUAGE C
       OUTPUT_NAME "unwind"
   )
 
-  if(LIBUNWIND_HIDE_SYMBOLS)
-    append_flags_if_supported(UNWIND_STATIC_LIBRARY_FLAGS -fvisibility=hidden)
-    append_flags_if_supported(UNWIND_STATIC_LIBRARY_FLAGS -fvisibility-global-new-delete-hidden)
-    target_compile_options(unwind_static PRIVATE ${UNWIND_STATIC_LIBRARY_FLAGS})
-    target_compile_definitions(unwind_static PRIVATE _LIBUNWIND_HIDE_SYMBOLS)
-  endif()
-
   list(APPEND LIBUNWIND_BUILD_TARGETS "unwind_static")
   if (LIBUNWIND_INSTALL_STATIC_LIBRARY)
     list(APPEND LIBUNWIND_INSTALL_TARGETS "unwind_static")