[libunwind] Provide a way to conveniently install libunwind headers

[rZhBoYao]

Summary

This adds a CMake option (defaults to OFF to not be intrusive) to activate 2 new targets install-unwind-headers and install-unwind-headers-stripped.
So, for example:

cmake -S runtimes -B build -G Ninja \
-DLLVM_ENABLE_RUNTIMES='libunwind' \
-DLIBUNWIND_INSTALL_HEADERS=ON

And then, ninja -C build install-unwind would install headers in addition to good ol' dylibs and archives, i.e., targets install-unwind* DEPENDS on install-unwind-headers*
On the other hand, ninja -C build install-unwind-headers gives you headers only.

[ldionne]

I believe unwind should be made to depend on unwind-header, and install-unwind on install-unwind-headers.

Also, instead of include_directories(include) in libunwind/CMakeLists.txt, we should be able to target_link_libraries(unwind_shared PRIVATE unwind-headers) (and similarly for the static library). That will require adding target_include_directories(unwind-headers INTERFACE <path-to-libunwind-include>).

libunwind/include/CMakeLists.txt

18

Why do we have that check?

[rZhBoYao]

All points addressed. I also updated the summary accordingly. Tested on macOS 12.1 and Ubuntu 20.04.2 LTS.

[rZhBoYao]

libunwind/include/CMakeLists.txt

18

Should've been NOT CMAKE_CONFIGURATION_TYPES AND LIBUNWIND_INSTALL_HEADERS. That must've slipped in when I cargo-culted it from other cmake file. I believe NOT CMAKE_CONFIGURATION_TYPES is meant to hide install-* targets from IDEs, since CMAKE_CONFIGURATION_TYPES is set only if the generator is an IDE say -GXcode and not -GNinja.

[ldionne]

libunwind/include/CMakeLists.txt

20–24

Instead, why don't we simply do

set(files
    __libunwind_config.h
    libunwind.h
    mach-o/compact_unwind_encoding.h
    unwind_arm_ehabi.h
    unwind_itanium.h
    unwind.h
    )

above and always include that header?

[rZhBoYao]

libunwind/include/CMakeLists.txt

20–24

At first, I actually tried that, only to find out mach-o/compact_unwind_encoding.h would then be installed as <CMAKE_INSTALL_PREFIX>/include/compact_unwind_encoding.h instead of <CMAKE_INSTALL_PREFIX>/include/mach-o/compact_unwind_encoding.h, which I think is undesirable.

[ldionne]

libunwind/include/CMakeLists.txt

20–24

I would replace it with this:

foreach(file ${files})
    get_filename_component(dir ${file} DIRECTORY)
    install(FILES ${file}
      DESTINATION "include/${dir}"
      COMPONENT unwind-headers
      PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
    )
endforeach()

That's what we do for libc++. That way, we don't have platform specific logic and it should work without modification if new headers are added in the future.

[rZhBoYao]

Address inline comment.

[ldionne]

Thank you!

[rZhBoYao]

Can you commit this for me? My name and email: PoYao Chang <[e-mail]>.
And thank you for your time!

[ldionne]

In D115535#3198156, @rZhBoYao wrote:

Can you commit this for me? My name and email: PoYao Chang <[e-mail]>.
And thank you for your time!

Thanks for the patch!

Ping @thakis in case you want to make a matching change to the gn build (sorry if not and this is just spamming you).

libunwind/CMakeLists.txt

 option(LIBUNWIND_ENABLE_THREADS "Build libunwind with threading support." ON)
 option(LIBUNWIND_WEAK_PTHREAD_LIB "Use weak references to refer to pthread functions." OFF)
 option(LIBUNWIND_USE_COMPILER_RT "Use compiler-rt instead of libgcc" OFF)
 option(LIBUNWIND_INCLUDE_DOCS "Build the libunwind documentation." ${LLVM_INCLUDE_DOCS})
 option(LIBUNWIND_INCLUDE_TESTS "Build the libunwind tests." ${LLVM_INCLUDE_TESTS})
 option(LIBUNWIND_IS_BAREMETAL "Build libunwind for baremetal targets." OFF)
 option(LIBUNWIND_USE_FRAME_HEADER_CACHE "Cache frame headers for unwinding. Requires locking dl_iterate_phdr." OFF)
 option(LIBUNWIND_REMEMBER_HEAP_ALLOC "Use heap instead of the stack for .cfi_remember_state." OFF)
+option(LIBUNWIND_INSTALL_HEADERS "Install the libunwind headers." OFF)
 
 set(LIBUNWIND_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
     "Define suffix of library directory name (32/64)")
 option(LIBUNWIND_INSTALL_LIBRARY "Install the libunwind library." ON)
 cmake_dependent_option(LIBUNWIND_INSTALL_STATIC_LIBRARY
   "Install the static libunwind library." ON
   "LIBUNWIND_ENABLE_STATIC;LIBUNWIND_INSTALL_LIBRARY" OFF)
 cmake_dependent_option(LIBUNWIND_INSTALL_SHARED_LIBRARY
if (LIBUNWIND_HAS_PTHREAD_LIB)
     add_definitions(-D_LIBUNWIND_LINK_PTHREAD_LIB)
   endif()
 endif()
 
 #===============================================================================
 # Setup Source Code
 #===============================================================================
 
-include_directories(include)
+add_subdirectory(include)
 
 add_subdirectory(src)
 
 if (LIBUNWIND_INCLUDE_DOCS)
   add_subdirectory(docs)
 endif()
 
 if (LIBUNWIND_INCLUDE_TESTS AND EXISTS ${LLVM_CMAKE_DIR})
   add_subdirectory(test)
 endif()

libunwind/include/CMakeLists.txt

+set(files
+    __libunwind_config.h
+    libunwind.h
+    mach-o/compact_unwind_encoding.h
+    unwind_arm_ehabi.h
+    unwind_itanium.h
+    unwind.h
+    )
+
+add_library(unwind-headers INTERFACE)
+target_include_directories(unwind-headers INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
+
+if(LIBUNWIND_INSTALL_HEADERS)
+  foreach(file ${files})
+    get_filename_component(dir ${file} DIRECTORY)
+    install(FILES ${file}
+      DESTINATION "include/${dir}"
+      COMPONENT unwind-headers
+      PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+    )
+  endforeach()
+
+  if(NOT CMAKE_CONFIGURATION_TYPES)
+    add_custom_target(install-unwind-headers
+      DEPENDS unwind-headers
+      COMMAND "${CMAKE_COMMAND}"
+              -DCMAKE_INSTALL_COMPONENT=unwind-headers
+              -P "${LIBUNWIND_BINARY_DIR}/cmake_install.cmake")
+    add_custom_target(install-unwind-headers-stripped DEPENDS install-unwind-headers)
+  endif()
+endif()

libunwind/src/CMakeLists.txt

 # Build the shared library.
 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})
+  target_link_libraries(unwind_shared PRIVATE ${LIBUNWIND_LIBRARIES}
+                                      PRIVATE unwind-headers)
   set_target_properties(unwind_shared
     PROPERTIES
       CXX_EXTENSIONS OFF
       CXX_STANDARD 11
       CXX_STANDARD_REQUIRED ON
       COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
       LINK_FLAGS "${LIBUNWIND_LINK_FLAGS}"
       LINKER_LANGUAGE C

 # Build the static library.
 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})
+  target_link_libraries(unwind_static PRIVATE ${LIBUNWIND_LIBRARIES}
+                                      PRIVATE unwind-headers)
   set_target_properties(unwind_static
     PROPERTIES
       CXX_EXTENSIONS OFF
       CXX_STANDARD 11
       CXX_STANDARD_REQUIRED ON
       COMPILE_FLAGS "${LIBUNWIND_COMPILE_FLAGS}"
       LINK_FLAGS "${LIBUNWIND_LINK_FLAGS}"
       LINKER_LANGUAGE C
COMMAND "${CMAKE_COMMAND}"
             -DCMAKE_INSTALL_COMPONENT=unwind
             -P "${LIBUNWIND_BINARY_DIR}/cmake_install.cmake")
   add_custom_target(install-unwind-stripped
     DEPENDS unwind
     COMMAND "${CMAKE_COMMAND}"
             -DCMAKE_INSTALL_COMPONENT=unwind
             -DCMAKE_INSTALL_DO_STRIP=1
             -P "${LIBUNWIND_BINARY_DIR}/cmake_install.cmake")
+  if(LIBUNWIND_INSTALL_HEADERS)
+    add_dependencies(install-unwind install-unwind-headers)
+    add_dependencies(install-unwind-stripped install-unwind-headers-stripped)
+  endif()
 endif()