[CMake] Explicitly specify paths to libc++abi in CrossWinToARMLinux.cmake

[broadwaylamb]

Summary

D69169, which was necessary for running libc++ tests on remote host, got reverted. I couldn't think of a less invasive way to achieve this behavior but specify libc++abi paths in our cache file.

I was wondering though if the assumptions I made in this patch regarding directory layout always hold.

[vvereschaka]

LGTM

[broadwaylamb]

Reverted this because it broke our buildbot: http://lab.llvm.org:8011/builders/llvm-clang-win-x-armv7l/builds/4704/steps/build-llvm-project/logs/stdio.

Going to investigate.

[broadwaylamb]

Add one more libc++abi header search path when building libc++

@vvereschaka this is supposed to fix the buildbot failure. It's more of a sweep under the rug type of fix. The real problem is that the value of the CMAKE_SOURCE_DIR variable is unexpected.

See for yourself.

Before 0197eac3330c04a49519f3e4dac38c4de605c654 I had the following in the build log:

-- Looking for cxxabi.h in C:/buildbot/as-builder-1/llvm-clang-win-x-armv7l/llvm-project/libcxxabi/include - found

After (note the missing 'llvm-project' component in the path):

-- Looking for cxxabi.h in C:/buildbot/as-builder-1/llvm-clang-win-x-armv7l/libcxxabi/include - not found

Maybe you have an idea of why this is happening? This all works fine on my machine even if I reproduce the directory layout used on the buildbot and invoke CMake from the build directory:

llvm-clang-win-x-armv7l
├───build
└───llvm-project

[vvereschaka]

I tried to reproduce the problem on the builder in a temporary folder and I found that CMAKE_SOURCE_DIR == CMAKE_BINARY_DIR == <build_dir>.
Here is a list of all CMAKE_ variables available on a moment of initial configuration:

-- CMAKE_AR: c:/buildbot/temp/build/bin/llvm-ar.exe
-- CMAKE_BINARY_DIR: C:/buildbot/temp/build
-- CMAKE_BUILD_TYPE: Release
-- CMAKE_CL_SHOWINCLUDES_PREFIX: Note: including file:
-- CMAKE_COMMAND: C:/Program Files/CMake/bin/cmake.exe
-- CMAKE_CPACK_COMMAND: C:/Program Files/CMake/bin/cpack.exe
-- CMAKE_CROSSCOMPILING: ON
-- CMAKE_CTEST_COMMAND: C:/Program Files/CMake/bin/ctest.exe
-- CMAKE_CURRENT_BINARY_DIR: C:/buildbot/temp/build
-- CMAKE_CURRENT_LIST_DIR: C:/buildbot/temp/llvm-project/clang/cmake/caches
-- CMAKE_CURRENT_LIST_FILE: C:/buildbot/temp/llvm-project/clang/cmake/caches/CrossWinToARMLinux.cmake
-- CMAKE_CURRENT_SOURCE_DIR: C:/buildbot/temp/build
-- CMAKE_CXX_FLAGS: -D__OPTIMIZE__
-- CMAKE_C_COMPILER_TARGET: armv7-linux-gnueabihf
-- CMAKE_FILES_DIRECTORY: /CMakeFiles
-- CMAKE_HOST_SYSTEM_NAME: Windows
-- CMAKE_HOST_WIN32: 1
-- CMAKE_INSTALL_PREFIX: ../install
-- CMAKE_MAJOR_VERSION: 3
-- CMAKE_MINOR_VERSION: 10
-- CMAKE_PATCH_VERSION: 2
-- CMAKE_ROOT: C:/Program Files/CMake/share/cmake-3.10
-- CMAKE_SOURCE_DIR: C:/buildbot/temp/build
-- CMAKE_TWEAK_VERSION: 0
-- CMAKE_VERSION: 3.10.2

Looks like this is a feature (bug?_ of CMake. CMake doc says

CMAKE_SOURCE_DIR
The path to the top level of the source tree.

This is the full path to the top level of the current CMake source tree. For an in-source build, this would be the same as CMAKE_BINARY_DIR.

When run in -P script mode, CMake sets the variables CMAKE_BINARY_DIR, CMAKE_SOURCE_DIR, CMAKE_CURRENT_BINARY_DIR and CMAKE_CURRENT_SOURCE_DIR to the current working directory.

-C could be some kind of the script mode. May be. We use CMake 3.10.2 on the builders.

I think may be it is optimal to use CMAKE_CURRENT_LIST_DIR to calculate a direct path to required file. We always know where it is.

Something like that

get_filename_component(LIBCXX_CXX_ABI_INCLUDE_PATHS
                       "${CMAKE_CURRENT_LIST_DIR}/../../../libcxxabi/include"
                       ABSOLUTE CACHE)

[broadwaylamb]

@vvereschaka very interesting. I've downloaded CMake 3.10.2 and finally been able to reproduce the issue locally. So it is a CMake bug which does not appear in the latest versions. I'll update this patch to use CMAKE_CURRENT_LIST_DIR and add a comment.

[broadwaylamb]

Use CMAKE_CURRENT_LIST_DIR instead of CMAKE_SOURCE_DIR for locating the llvm-project directory.

[vvereschaka]

LGTM
I was able to build with these changes successfully on the local builder host.

clang/cmake/caches/CrossWinToARMLinux.cmake

 #       <llvm_src_root>/llvm-project/llvm
 # Build:
 #  cmake --build . --target install
 # Test:
 #  cmake --build . --target check-llvm
 #  cmake --build . --target check-clang
 #  cmake --build . --target check-lld
 
+# LLVM_PROJECT_DIR is the path to the llvm-project directory.
+# The right way to compute it would probably be to use "${CMAKE_SOURCE_DIR}/../",
+# but CMAKE_SOURCE_DIR is set to the wrong value on earlier CMake versions
+# that we still need to support (for instance, 3.10.2).
+get_filename_component(LLVM_PROJECT_DIR
+                       "${CMAKE_CURRENT_LIST_DIR}/../../../"
+                       ABSOLUTE)
+
 if (NOT DEFINED DEFAULT_SYSROOT)
   message(WARNING "DEFAULT_SYSROOT must be specified for the cross toolchain build.")
 endif()
 
 if (DEFINED LLVM_AR)
   set(CMAKE_AR "${LLVM_AR}" CACHE STRING "")
 endif()
 

 set(LIBCXXABI_SYSROOT                       "${DEFAULT_SYSROOT}" CACHE STRING "")
 set(LIBCXXABI_LINK_TESTS_WITH_SHARED_LIBCXXABI OFF CACHE BOOL "")
 set(LIBCXXABI_LINK_TESTS_WITH_SHARED_LIBCXX    OFF CACHE BOOL "")
 
 set(LIBCXX_USE_COMPILER_RT                  ON CACHE BOOL "")
 set(LIBCXX_TARGET_TRIPLE                    "${CMAKE_C_COMPILER_TARGET}" CACHE STRING "")
 set(LIBCXX_SYSROOT                          "${DEFAULT_SYSROOT}" CACHE STRING "")
 set(LIBCXX_ENABLE_SHARED                    OFF CACHE BOOL "")
+set(LIBCXX_CXX_ABI                          "libcxxabi" CACHE STRING "")
+set(LIBCXX_CXX_ABI_INCLUDE_PATHS            "${LLVM_PROJECT_DIR}/libcxxabi/include" CACHE PATH "")
+set(LIBCXX_CXX_ABI_LIBRARY_PATH             "${CMAKE_BINARY_DIR}/lib/${LIBCXX_TARGET_TRIPLE}/c++" CACHE PATH "")
 
 set(BUILTINS_CMAKE_ARGS                     "-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_AR=${CMAKE_AR}" CACHE STRING "")
 set(RUNTIMES_CMAKE_ARGS                     "-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_AR=${CMAKE_AR}" CACHE STRING "")
 
 # Remote test configuration.
 if(DEFINED REMOTE_TEST_HOST)
   set(DEFAULT_TEST_EXECUTOR                 "SSHExecutor('${REMOTE_TEST_HOST}', '${REMOTE_TEST_USER}')")
   set(DEFAULT_TEST_TARGET_INFO              "libcxx.test.target_info.LinuxRemoteTI")