[libcxxabi] Allow target flags to affect configuration tests.

[EricWF]

Summary

This patch changes the libc++abi CMake so that it adds certain target flags like '-m32' or '--gcc-toolchain' before including config-ix.cmake.
Since these flags can affect things like check_library_exists([...]) they needed to be added before the tests are performed.

Additionally this patch adds LIBCXXABI_BUILD_32_BITS which defaults to LLVM_BUILD_32_BITS.

This patch fixes:

https://llvm.org/bugs/show_bug.cgi?id=27950
https://llvm.org/bugs/show_bug.cgi?id=27959

[EricWF]

Add missing declaration for LIBCXXABI_TARGET_TRIPLE option.

[compnerd]

CMakeLists.txt

201

Why not handle this like libunwind? Alternative, we could duplicate this into libunwind. But we should behave similarly across the two I think.

219

No CMAKE_LINKER_FLAGS like libunwind/libc++?

234

This should be "--sysroot=${LIBCXXABI_SYSROOT}"

[EricWF]

Address review comments

• Add '=' in sysroot flag.

[EricWF]

CMakeLists.txt

201

I just forgot to copy/paste it. I'll check it in.

219

CMAKE_LINKER_FLAGS isn't a thing. libunwind and libc++ both use <PROJECT>_LINK_FLAGS.

Also CMAKE_COMPILE_FLAGS is not a CMake variable either. (which I did replace in libunwind).

[EricWF]

CMakeLists.txt

201

Done in r271462.

[EricWF]

Accepting after speaking to @compnerd.

CMakeLists.txt

 # Define options.
 option(LIBCXXABI_ENABLE_EXCEPTIONS "Use exceptions." ON)
 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)
 option(LIBCXXABI_HAS_PTHREAD_API "Ignore auto-detection and force use of pthread API" OFF)
+option(LIBCXXABI_BUILD_32_BITS "Build 32 bit libc++abi." ${LLVM_BUILD_32_BITS})
+set(LIBCXXABI_TARGET_TRIPLE "" CACHE STRING "Target triple for cross compiling.")
 set(LIBCXXABI_GCC_TOOLCHAIN "" CACHE PATH "GCC toolchain for cross compiling.")
 set(LIBCXXABI_SYSROOT "" CACHE PATH "Sysroot for cross compiling.")
 set(LIBCXXABI_LIBCXX_LIBRARY_PATH "" CACHE PATH "The path to libc++ library.")
 
 # 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

 
 # 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.
-include(config-ix)
-
 set(LIBCXXABI_COMPILER    ${CMAKE_CXX_COMPILER})
 set(LIBCXXABI_SOURCE_DIR  ${CMAKE_CURRENT_SOURCE_DIR})
 set(LIBCXXABI_BINARY_DIR  ${CMAKE_CURRENT_BINARY_DIR})
 set(LIBCXXABI_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXXABI_LIBDIR_SUFFIX})
 
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBCXXABI_LIBRARY_DIR})
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBCXXABI_LIBRARY_DIR})
 
 # By default, for non-standalone builds, libcxx and libcxxabi share a library
 # directory.
 if (NOT LIBCXXABI_LIBCXX_LIBRARY_PATH)
   set(LIBCXXABI_LIBCXX_LIBRARY_PATH "${LIBCXXABI_LIBRARY_DIR}" CACHE PATH
       "The path to libc++ library.")
 endif ()
 
+
+# Check that we can build with 32 bits if requested.
+if (CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32)
+  if (LIBCXXABI_BUILD_32_BITS AND NOT LLVM_BUILD_32_BITS) # Don't duplicate the output from LLVM
+    message(STATUS "Building 32 bits executables and libraries.")
+  endif()
+elseif(LIBCXXABI_BUILD_32_BITS)
+  message(FATAL_ERROR "LIBCXXABI_BUILD_32_BITS=ON is not supported on this platform.")
+endif()
+
 #===============================================================================
 # Setup Compiler Flags
 #===============================================================================
 
 # Get required flags.
 macro(append_if list condition var)
   if (${condition})
     list(APPEND ${list} ${var})
   endif()
 endmacro()
 
+macro(add_target_flags_if condition var)
+  if (${condition})
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${var}")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${var}")
+    list(APPEND LIBCXXABI_LINK_FLAGS ${var})
+  endif()
+endmacro()
+
 set(LIBCXXABI_C_FLAGS "")
 set(LIBCXXABI_CXX_FLAGS "")
 set(LIBCXXABI_COMPILE_FLAGS "")
 set(LIBCXXABI_LINK_FLAGS "")
 
+# Configure target flags
+add_target_flags_if(LIBCXXABI_BUILD_32_BITS "-m32")
+add_target_flags_if(LIBCXXABI_TARGET_TRIPLE
+          "-target ${LIBCXXABI_TARGET_TRIPLE}")
+add_target_flags_if(LIBCXXABI_GCC_TOOLCHAIN
+         "-gcc-toolchain ${LIBCXXABI_GCC_TOOLCHAIN}")
+add_target_flags_if(LIBCXXABI_SYSROOT
+          "--sysroot=${LIBCXXABI_SYSROOT}")
+
+# Configure compiler. Must happen after setting the target flags.
+include(config-ix)
 
 if (LIBCXXABI_HAS_NOSTDINCXX_FLAG)
   list(APPEND LIBCXXABI_COMPILE_FLAGS -nostdinc++)
   # Remove -stdlib flags to prevent them from causing an unused flag warning.
   string(REPLACE "-stdlib=libc++" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
   string(REPLACE "-stdlib=libstdc++" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
 endif()
 
if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif()
 
 # Define LIBCXXABI_USE_LLVM_UNWINDER for conditional compilation.
 if (LIBCXXABI_USE_LLVM_UNWINDER OR LLVM_NATIVE_ARCH MATCHES ARM)
   add_definitions(-DLIBCXXABI_USE_LLVM_UNWINDER=1)
 endif()
 
-append_if(LIBCXXABI_COMPILE_FLAGS LIBCXXABI_TARGET_TRIPLE
-          "-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} ${LIBCXXABI_CXX_FLAGS}")
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${LIBCXXABI_C_FLAGS}")
 
 #===============================================================================
 # Setup Source Code
 #===============================================================================
 

test/CMakeLists.txt

 macro(pythonize_bool var)
   if (${var})
     set(${var} True)
   else()
     set(${var} False)
   endif()
 endmacro()
 
 if (NOT DEFINED LIBCXX_ENABLE_SHARED)
   set(LIBCXX_ENABLE_SHARED ON)
 endif()
 
-pythonize_bool(LLVM_BUILD_32_BITS)
+pythonize_bool(LIBCXXABI_BUILD_32_BITS)
 pythonize_bool(LIBCXX_ENABLE_SHARED)
 pythonize_bool(LIBCXXABI_ENABLE_SHARED)
 pythonize_bool(LIBCXXABI_ENABLE_THREADS)
 pythonize_bool(LIBCXXABI_ENABLE_EXCEPTIONS)
 pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
 pythonize_bool(LIBCXXABI_HAS_CXA_THREAD_ATEXIT_IMPL)
 set(LIBCXXABI_TARGET_INFO "libcxx.test.target_info.LocalTI" CACHE STRING
     "TargetInfo to use when setting up test environment.")

test/lit.site.cfg.in

 @AUTO_GEN_COMMENT@
 config.cxx_under_test           = "@LIBCXXABI_COMPILER@"
 config.project_obj_root         = "@CMAKE_BINARY_DIR@"
 config.libcxxabi_src_root       = "@LIBCXXABI_SOURCE_DIR@"
 config.libcxxabi_obj_root       = "@LIBCXXABI_BINARY_DIR@"
 config.abi_library_path         = "@LIBCXXABI_LIBRARY_DIR@"
 config.libcxx_src_root          = "@LIBCXXABI_LIBCXX_PATH@"
 config.cxx_headers              = "@LIBCXXABI_LIBCXX_INCLUDES@"
 config.cxx_library_root         = "@LIBCXXABI_LIBCXX_LIBRARY_PATH@"
 config.llvm_unwinder            = "@LIBCXXABI_USE_LLVM_UNWINDER@"
 config.enable_threads           = "@LIBCXXABI_ENABLE_THREADS@"
 config.use_sanitizer            = "@LLVM_USE_SANITIZER@"
-config.enable_32bit             = "@LLVM_BUILD_32_BITS@"
+config.enable_32bit             = "@LIBCXXABI_BUILD_32_BITS@"
 config.target_info              = "@LIBCXXABI_TARGET_INFO@"
 config.executor                 = "@LIBCXXABI_EXECUTOR@"
 config.thread_atexit            = "@LIBCXXABI_HAS_CXA_THREAD_ATEXIT_IMPL@"
 config.libcxxabi_shared         = "@LIBCXXABI_ENABLE_SHARED@"
 config.enable_shared            = "@LIBCXX_ENABLE_SHARED@"
 config.enable_exceptions        = "@LIBCXXABI_ENABLE_EXCEPTIONS@"
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@LIBCXXABI_SOURCE_DIR@/test/lit.cfg")