[libc++abi] Add support for cross compiling.

[danalbert]

This will need to be revisited to inform LIT once http://reviews.llvm.org/D6985 lands.

CMakeLists.txt

140

Same comments from http://reviews.llvm.org/D6990 apply.

[danalbert]

Remove LIBCXXABI_CROSSCOMPILING. Same reasoning as D6990.

[jroelofs]

LGTM

[danalbert]

Use set() instead of option() for string options.

CMakeLists.txt

 #===============================================================================
 
 # Define options.
 option(LIBCXXABI_ENABLE_ASSERTIONS "Enable assertions independent of build mode." ON)
 option(LIBCXXABI_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
 option(LIBCXXABI_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
 option(LIBCXXABI_USE_LLVM_UNWINDER "Build and use the LLVM unwinder." OFF)
 option(LIBCXXABI_ENABLE_THREADS "Build with threads enabled" ON)
+set(LIBCXXABI_GCC_TOOLCHAIN "" CACHE STRING "GCC toolchain for cross compiling.")
+set(LIBCXXABI_SYSROOT "" CACHE STRING "Sysroot for cross compiling.")
 
 # Default to building a shared library so that the default options still test
 # the libc++abi that is being built. There are two problems with testing a
 # static libc++abi. In the case of a standalone build, the tests will link the
 # system's libc++, which might not have been built against our libc++abi. In the
 # case of an in tree build, libc++ will prefer a dynamic libc++abi from the
 # system over a static libc++abi from the output directory.
 option(LIBCXXABI_ENABLE_SHARED "Build libc++abi as a shared library." ON)
 
 find_path(
   LIBCXXABI_LIBCXX_INCLUDES
   vector
   PATHS ${LIBCXXABI_LIBCXX_INCLUDES}
         ${CMAKE_BINARY_DIR}/${LIBCXXABI_LIBCXX_INCLUDES}
         ${LLVM_MAIN_SRC_DIR}/projects/libcxx/include
         ${LLVM_INCLUDE_DIR}/c++/v1
   )
 
 set(LIBCXXABI_LIBCXX_INCLUDES "${LIBCXXABI_LIBCXX_INCLUDES}" CACHE STRING
     "Specify path to libc++ includes." FORCE)
 
 #===============================================================================
 # Configure System
 #===============================================================================
 
 # Add path for custom modules
 set(CMAKE_MODULE_PATH
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
   ${CMAKE_MODULE_PATH}
   )
 
 # Configure compiler.
if (NOT LIBCXXABI_ENABLE_THREADS)
   add_definitions(-DLIBCXXABI_HAS_NO_THREADS=1)
 endif()
 
 # This is the _ONLY_ place where add_definitions is called.
 if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif()
 
+list(APPEND LIBCXXABI_COMPILE_FLAGS "-target ${LIBCXXABI_TARGET_TRIPLE}")
+append_if(LIBCXXABI_COMPILE_FLAGS LIBCXXABI_GCC_TOOLCHAIN
+         "-gcc-toolchain ${LIBCXXABI_GCC_TOOLCHAIN}")
+append_if(LIBCXXABI_COMPILE_FLAGS LIBCXXABI_SYSROOT
+          "--sysroot ${LIBCXXABI_SYSROOT}")
 string(REPLACE ";" " " LIBCXXABI_CXX_FLAGS "${LIBCXXABI_CXX_FLAGS}")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${LIBCXXABI_CXX_FLAGS}")
 
 #===============================================================================
 # Setup Source Code
 #===============================================================================
 
 include_directories(include)