[libcxx] Add support for building and testing with an ABI library not along linker paths

Summary:
This patch adds support for building/testing libc++ with an ABI library that the linker would not normally find.

- `CMAKE_LIBRARY_PATH` is used to specify the list of search directories.
- The ABI library is now found using `find_library` instead of assuming its along the linker's search path.
- `CMAKE_LIBRARY_PATH` is passed to our LIT config as `library_paths`.
- For each path in `library_paths` the following flags are added `-L<path> -Wl,-rpath -Wl,<path>`

Some changes in existing behavior were also added:
- `target_link_libraries` is now passed the ABI library file instead of the library name. Ex `target_link_libraries(cxx "/usr/lib/libc++abi.so")` vs `target_link_libraries(cxx "c++abi")`.
- `-Wl,-rpath -Wl,<path>` is now used on OSX to link to libc++ instead of env['DYLD_LIBRARY_PATH'] if `use_system_lib=False`.




Reviewers: mclow.lists, danalbert, EricWF

Reviewed By: EricWF

Subscribers: emaste, cfe-commits

Differential Revision: http://reviews.llvm.org/D5038

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@220118 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/Modules/HandleLibCXXABI.cmake

@@ -0,0 +1,111 @@
+
+#===============================================================================
+# Add an ABI library if appropriate
+#===============================================================================
+
+#
+# _setup_abi: Set up the build to use an ABI library
+#
+# Parameters:
+#   abidefines: A list of defines needed to compile libc++ with the ABI library
+#   abilibs   : A list of libraries to link against
+#   abifiles  : A list of files (which may be relative paths) to copy into the
+#               libc++ build tree for the build.  These files will also be
+#               installed alongside the libc++ headers.
+#   abidirs   : A list of relative paths to create under an include directory
+#               in the libc++ build directory.
+#
+macro(setup_abi_lib abipathvar abidefines abilibs abifiles abidirs)
+  list(APPEND LIBCXX_CXX_FEATURE_FLAGS ${abidefines})
+  set(${abipathvar} "${${abipathvar}}"
+    CACHE PATH
+    "Paths to C++ ABI header directories separated by ';'." FORCE
+    )
+
+  # To allow for libraries installed along non-default paths we use find_library
+  # to locate the ABI libraries we want. Making sure to clean the cache before
+  # each run of find_library.
+  set(LIBCXX_CXX_ABI_LIBRARIES "")
+  foreach(alib ${abilibs})
+    unset(_Res CACHE)
+    find_library(_Res ${alib})
+    if (${_Res} STREQUAL "_Res-NOTFOUND")
+      message(FATAL_ERROR "Failed to find ABI library: ${alib}")
+    else()
+      message(STATUS "Adding ABI library: ${_Res}")
+      list(APPEND LIBCXX_CXX_ABI_LIBRARIES ${_Res})
+    endif()
+  endforeach()
+
+  set(LIBCXX_ABILIB_FILES ${abifiles})
+
+  file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/include")
+  foreach(_d ${abidirs})
+    file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/include/${_d}")
+  endforeach()
+
+  foreach(fpath ${LIBCXX_ABILIB_FILES})
+    set(found FALSE)
+    foreach(incpath ${${abipathvar}})
+      if (EXISTS "${incpath}/${fpath}")
+        set(found TRUE)
+        get_filename_component(dstdir ${fpath} PATH)
+        get_filename_component(ifile ${fpath} NAME)
+        file(COPY "${incpath}/${fpath}"
+          DESTINATION "${CMAKE_BINARY_DIR}/include/${dstdir}"
+          )
+        install(FILES "${CMAKE_BINARY_DIR}/include/${fpath}"
+          DESTINATION include/c++/v1/${dstdir}
+          PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+          )
+        list(APPEND abilib_headers "${CMAKE_BINARY_DIR}/include/${fpath}")
+      endif()
+    endforeach()
+    if (NOT found)
+      message(FATAL_ERROR "Failed to find ${fpath}")
+    endif()
+  endforeach()
+
+  add_custom_target(LIBCXX_CXX_ABI_DEPS DEPENDS ${abilib_headers})
+  include_directories("${CMAKE_BINARY_DIR}/include")
+
+endmacro()
+
+if ("${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libstdc++" OR
+    "${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libsupc++")
+  set(_LIBSUPCXX_INCLUDE_FILES
+    cxxabi.h bits/c++config.h bits/os_defines.h bits/cpu_defines.h
+    bits/cxxabi_tweaks.h bits/cxxabi_forced.h
+    )
+  if ("${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libstdc++")
+    set(_LIBSUPCXX_DEFINES "-DLIBSTDCXX")
+    set(_LIBSUPCXX_LIBNAME stdc++)
+  else()
+    set(_LIBSUPCXX_DEFINES "")
+    set(_LIBSUPCXX_LIBNAME supc++)
+  endif()
+  setup_abi_lib("LIBCXX_LIBSUPCXX_INCLUDE_PATHS"
+    "-D__GLIBCXX__ ${_LIBSUPCXX_DEFINES}"
+    "${_LIBSUPCXX_LIBNAME}" "${_LIBSUPCXX_INCLUDE_FILES}" "bits"
+    )
+elseif ("${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libcxxabi")
+  if (LIBCXX_CXX_ABI_INTREE)
+    # Link against just-built "cxxabi" target.
+    set(CXXABI_LIBNAME cxxabi)
+  else()
+    # Assume c++abi is installed in the system, rely on -lc++abi link flag.
+    set(CXXABI_LIBNAME "c++abi")
+  endif()
+  setup_abi_lib("LIBCXX_LIBCXXABI_INCLUDE_PATHS" ""
+    ${CXXABI_LIBNAME} "cxxabi.h" ""
+    )
+elseif ("${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libcxxrt")
+  setup_abi_lib("LIBCXX_LIBCXXRT_INCLUDE_PATHS" "-DLIBCXXRT"
+    "cxxrt" "cxxabi.h;unwind.h;unwind-arm.h;unwind-itanium.h" ""
+    )
+elseif (NOT "${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "none")
+  message(FATAL_ERROR
+    "Currently libstdc++, libsupc++, libcxxabi, libcxxrt and none are "
+    "supported for c++ abi."
+    )
+endif ()