[libunwind] Allow building both shared and static library

[phosek]

Summary

This change allows building both shared and static version of libunwind in a single build, sharing object files between both versions.

[compnerd]

src/CMakeLists.txt

101

Please indent this to align up to the arguments as it was previously.

112

Similar.

126

Similar.

CMakeLists.txt

 option(LIBUNWIND_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
 option(LIBUNWIND_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
 option(LIBUNWIND_ENABLE_SHARED "Build libunwind as a shared library." ON)
+option(LIBUNWIND_ENABLE_STATIC "Build libunwind as a static library." ON)
 option(LIBUNWIND_ENABLE_CROSS_UNWINDING "Enable cross-platform unwinding support." OFF)
 option(LIBUNWIND_ENABLE_ARM_WMMX "Enable unwinding support for ARM WMMX registers." OFF)
 

 set(LIBUNWIND_GCC_TOOLCHAIN "" CACHE PATH "GCC toolchain for cross compiling.")
 set(LIBUNWIND_SYSROOT "" CACHE PATH "Sysroot for cross compiling.")
 
+if (NOT LIBUNWIND_ENABLE_SHARED AND NOT LIBUNWIND_ENABLE_STATIC)
+  message(FATAL_ERROR "libunwind must be built as either a shared or static library.")
+endif()
 
 # Check that we can build with 32 bits if requested.
 if (CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32)

src/CMakeLists.txt

     ${LIBUNWIND_C_SOURCES}
     ${LIBUNWIND_ASM_SOURCES})
 
-if (LIBUNWIND_ENABLE_SHARED)
-  add_library(unwind SHARED ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
-else()
-  add_library(unwind STATIC ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
-endif ()
-
 # Generate library list.
 set(libraries ${LIBUNWINDCXX_ABI_LIBRARIES})
 append_if(libraries LIBUNWIND_HAS_C_LIB c)
 append_if(libraries LIBUNWIND_HAS_DL_LIB dl)
 append_if(libraries LIBUNWIND_HAS_PTHREAD_LIB pthread)
 
-target_link_libraries(unwind ${libraries})
-
 # Setup flags.
 append_if(LIBUNWIND_COMPILE_FLAGS LIBUNWIND_HAS_FPIC_FLAG -fPIC)
 append_if(LIBUNWIND_CXX_FLAGS LIBUNWIND_HAS_NO_RTTI_FLAG -fno-rtti)

 string(REPLACE ";" " " LIBUNWIND_C_FLAGS "${LIBUNWIND_C_FLAGS}")
 string(REPLACE ";" " " LIBUNWIND_LINK_FLAGS "${LIBUNWIND_LINK_FLAGS}")
 
-set_target_properties(unwind
-                      PROPERTIES
-                        COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
-                        LINK_FLAGS    "${LIBUNWIND_LINK_FLAGS}"
-                        OUTPUT_NAME   "unwind"
-                        VERSION       "1.0"
-                        SOVERSION     "1")
 set_property(SOURCE ${LIBUNWIND_CXX_SOURCES}
              APPEND_STRING PROPERTY COMPILE_FLAGS " ${CMAKE_CXX_FLAGS} ${LIBUNWIND_CXX_FLAGS}")
 set_property(SOURCE ${LIBUNWIND_C_SOURCES}
              APPEND_STRING PROPERTY COMPILE_FLAGS " ${CMAKE_C_FLAGS} ${LIBUNWIND_C_FLAGS}")
 
-install(TARGETS unwind
+# Add a object library that contains the compiled source files.
+add_library(unwind_objects OBJECT ${LIBUNWIND_SOURCES} ${LIBUNWIND_HEADERS})
+
+set_target_properties(unwind_objects
+                      PROPERTIES
+                        COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}")
+
+set(LIBUNWIND_TARGETS)
+
+# Build the shared library.
+if (LIBUNWIND_ENABLE_SHARED)
+  add_library(unwind_shared SHARED $<TARGET_OBJECTS:unwind_objects>)
+  target_link_libraries(unwind_shared ${libraries})
+  set_target_properties(unwind_shared
+                        PROPERTIES
+                          LINK_FLAGS    "${LIBUNWIND_LINK_FLAGS}"
+                          OUTPUT_NAME   "unwind"
+                          VERSION       "1.0"
+                          SOVERSION     "1")
+  list(APPEND LIBUNWIND_TARGETS "unwind_shared")
+endif ()
+
+# Build the static library.
+if (LIBUNWIND_ENABLE_STATIC)
+  add_library(unwind_static STATIC $<TARGET_OBJECTS:unwind_objects>)
+  target_link_libraries(unwind_static ${libraries})
+  set_target_properties(unwind_static
+                        PROPERTIES
+                          LINK_FLAGS    "${LIBUNWIND_LINK_FLAGS}"
+                          OUTPUT_NAME   "unwind")
+  list(APPEND LIBUNWIND_TARGETS "unwind_static")
+endif ()
+
+# Add a meta-target for both libraries.
+add_custom_target(unwind DEPENDS ${LIBUNWIND_TARGETS})
+
+install(TARGETS ${LIBUNWIND_TARGETS}
         LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX})