[runtimes] Remove FOO_TARGET_TRIPLE, FOO_SYSROOT and FOO_GCC_TOOLCHAIN

[ldionne]

Summary

Instead, folks can use the equivalent variables provided by CMake
to set those. This is an alternative to D111672.

[ldionne]

I have the feeling that this is going to break people, but I'm investigating this patch as requested in D111672.

[ldionne]

Rebase onto main

[compnerd]

I think that as long as the builders remain green, this is fine. Yes, this is very likely to break users. We should announce this change on llvm-dev at the very least, and you *could* possibly add a transition helper in the form of:

if(NOT CMAKE_SYSROOT AND LIBCXX_SYSROOT)
  message(SEND_WARNING "LIBCXX_SYSROOT is deprecated, please use CMAKE_SYSROOT")
  set(CMAKE_SYSROOT ${LIBCXX_SYSROOT} CACHE STRING "" FORCE)
endif()

I think that having a nice transition would be preferable, and we could drop it in the next release.

[phosek]

I went through my notes and the reason I introduced these flags was to support the scenario where you use LLVM_ENABLE_PROJECTS=clang;libcxx;... and you want to build libc++ (and other runtimes) for target other than host, so you cannot use CMAKE_CXX_COMPILER_TARGET or CMAKE_SYSROOT because that would also affect the tools build.

That predates the bootstrapping (née runtimes) build support and is very limited (you can only build runtimes for one target, you can only vary a few flags, you're still using the host compiler so you likely need a two-stage build) which is why we haven't used it ever since bootstrapping build became available.

I don't know if anyone still uses this support, but even if so we should steer them towards the bootstrapping build. I agree with @compnerd that providing a deprecation message for now and removing them in the next release might be preferable.

[ldionne]

Rebase onto main after adding a deprecation message.

[ldionne]

Thanks a lot for the discussion @compnerd and @phosek , and sorry this slept for so long. But I think we should be good to move forward with this now.

[ldionne]

Fix ABI list issue.

[ldionne]

@phosek Is this fine with you? And @compnerd is this still fine with you too?

If so, I'll check this in during the week of Feb 28 (when I return from vacation) so I can be available in case any issues come up.

[phosek]

LGTM

[ldionne]

Poke CI after rebasing. I'll land this tomorrow if CI is green.

[ldionne]

I'm going to land this now, however I'll use message(WARNING instead of message(FATAL_ERROR to avoid requiring a CMake cache rebuild for everyone.

[simoll]

Remark: Targets need to specify CMAKE_ASM_COMPILER_TARGET or UnwindRegistersRestore|Save.S will be assembled for the default target, not the CMAKE_C|CXX_COMPILER_TARGET.
This caused the libunwind miscompile for the clang-ve-ninja bot: https://lab.llvm.org/buildbot/#/builders/91/builds/4728

[ldionne]

In D112155#3353869, @simoll wrote:

Remark: Targets need to specify CMAKE_ASM_COMPILER_TARGET or UnwindRegistersRestore|Save.S will be assembled for the default target, not the CMAKE_C|CXX_COMPILER_TARGET.
This caused the libunwind miscompile for the clang-ve-ninja bot: https://lab.llvm.org/buildbot/#/builders/91/builds/4728

Damn, that is tricky. Thanks for the heads up. Do you think we should set CMAKE_ASM_COMPILER_TARGET to CMAKE_CXX_COMPILER_TARGET? Or perhaps we could do something like:

if (NOT CMAKE_ASM_COMPILER_TARGET STREQUAL CMAKE_CXX_COMPILER_TARGET)
  message(FATAL_ERROR "I'm sure this is an oversight!")
endif()

if (NOT CMAKE_C_COMPILER_TARGET STREQUAL CMAKE_CXX_COMPILER_TARGET)
  message(FATAL_ERROR "I'm sure this is an oversight!")
endif()

Anything to either avoid the miscompile would be better than the status quo, which is kind of a trap.

[simoll]

In D112155#3360144, @ldionne wrote:

In D112155#3353869, @simoll wrote:

Remark: Targets need to specify CMAKE_ASM_COMPILER_TARGET or UnwindRegistersRestore|Save.S will be assembled for the default target, not the CMAKE_C|CXX_COMPILER_TARGET.
This caused the libunwind miscompile for the clang-ve-ninja bot: https://lab.llvm.org/buildbot/#/builders/91/builds/4728

Damn, that is tricky. Thanks for the heads up. Do you think we should set CMAKE_ASM_COMPILER_TARGET to CMAKE_CXX_COMPILER_TARGET? [..]
Or perhaps we could do something like:

if (NOT CMAKE_ASM_COMPILER_TARGET STREQUAL CMAKE_CXX_COMPILER_TARGET)
  message(FATAL_ERROR "I'm sure this is an oversight!")
endif()

if (NOT CMAKE_C_COMPILER_TARGET STREQUAL CMAKE_CXX_COMPILER_TARGET)
  message(FATAL_ERROR "I'm sure this is an oversight!")
endif()

Anything to either avoid the miscompile would be better than the status quo, which is kind of a trap.

Do we really know that the ASM target is always the same as the C|CXX target?
+1 for emitting a warning at least. FATAL_ERROR if we know for sure that these are always the same.

libcxx/CMakeLists.txt

option(LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS
    instead. If you define them in libc++, make sure they are NOT defined in
    libc++abi. Doing otherwise is an ODR violation." OFF)
 # Build libc++abi with libunwind. We need this option to determine whether to
 # link with libunwind or libgcc_s while running the test cases.
 option(LIBCXXABI_USE_LLVM_UNWINDER "Build and use the LLVM unwinder." OFF)
 
 # Target options --------------------------------------------------------------
 option(LIBCXX_BUILD_32_BITS "Build 32 bit libc++." ${LLVM_BUILD_32_BITS})
-set(LIBCXX_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Use alternate target triple.")
-set(LIBCXX_SYSROOT "" CACHE STRING "Use alternate sysroot.")
-set(LIBCXX_GCC_TOOLCHAIN "" CACHE STRING "Use alternate GCC toolchain.")
 
 # Feature options -------------------------------------------------------------
 option(LIBCXX_ENABLE_EXCEPTIONS "Use exceptions." ON)
 option(LIBCXX_ENABLE_RTTI "Use run time type information." ON)
 option(LIBCXX_ENABLE_THREADS "Build libc++ with support for threads." ON)
 option(LIBCXX_ENABLE_MONOTONIC_CLOCK
   "Build libc++ with support for a monotonic clock.
    This option may only be set to OFF when LIBCXX_ENABLE_THREADS=OFF." ON)

 include(HandleLibcxxFlags)
 
 # Target flags ================================================================
 # These flags get added to CMAKE_CXX_FLAGS and CMAKE_C_FLAGS so that
 # 'config-ix' use them during feature checks. It also adds them to both
 # 'LIBCXX_COMPILE_FLAGS' and 'LIBCXX_LINK_FLAGS'
 add_target_flags_if(LIBCXX_BUILD_32_BITS "-m32")
 
-if(LIBCXX_TARGET_TRIPLE)
-  add_target_flags_if_supported("--target=${LIBCXX_TARGET_TRIPLE}")
-elseif(CMAKE_CXX_COMPILER_TARGET)
-  set(LIBCXX_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
-endif()
-if(LIBCXX_SYSROOT)
-  add_target_flags_if_supported("--sysroot=${LIBCXX_SYSROOT}")
-elseif(CMAKE_SYSROOT)
-  set(LIBCXX_SYSROOT "${CMAKE_SYSROOT}")
-endif()
-if(LIBCXX_GCC_TOOLCHAIN)
-  add_target_flags_if_supported("--gcc-toolchain=${LIBCXX_GCC_TOOLCHAIN}")
-elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
-  set(LIBCXX_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
-endif()
-
 # Configure compiler.
 include(config-ix)
 
 # Configure coverage options.
 if (LIBCXX_GENERATE_COVERAGE)
   include(CodeCoverage)
   set(CMAKE_BUILD_TYPE "COVERAGE" CACHE STRING "" FORCE)
 endif()

libcxx/cmake/caches/AArch64.cmake

 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "aarch64-linux-gnu" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "aarch64-linux-gnu" CACHE STRING "")

libcxx/cmake/caches/Armv7Arm.cmake

 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv7-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv7-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-marm" CACHE STRING "")
 set(CMAKE_C_FLAGS "-marm" CACHE STRING "")

libcxx/cmake/caches/Armv7Thumb-noexceptions.cmake

 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv7-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv7-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
 set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")

libcxx/cmake/caches/Armv8Arm.cmake

 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv8-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv8-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-marm" CACHE STRING "")
 set(CMAKE_C_FLAGS "-marm" CACHE STRING "")

libcxx/cmake/caches/Armv8Thumb-noexceptions.cmake

 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv8-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv8-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
 set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")

libcxx/docs/BuildingLibcxx.rst

> cmake -G Ninja -S libcxx -B build                                                 ^
           -DCMAKE_C_COMPILER=clang-cl                                                 ^
           -DCMAKE_CXX_COMPILER=clang-cl                                               ^
           -DLIBCXX_ENABLE_EXPERIMENTAL_LIBRARY=NO
   > ninja -C build cxx
   > ninja -C build check-cxx
 
 If you are running in an MSYS2 shell and you have installed the
 MSYS2-provided clang package (which defaults to a non-MSVC target), you
-should add e.g. ``-DLIBCXX_TARGET_TRIPLE=x86_64-windows-msvc`` (replacing
+should add e.g. ``-DCMAKE_CXX_COMPILER_TARGET=x86_64-windows-msvc`` (replacing
 ``x86_64`` with the architecture you're targeting) to the ``cmake`` command
 line above. This will instruct ``check-cxx`` to use the right target triple
 when invoking ``clang++``.
 
 Also note that if not building in Release mode, a failed assert in the tests
 pops up a blocking dialog box, making it hard to run a larger number of tests.
 
 CMake + ninja (MinGW)

libcxx/lib/abi/CMakeLists.txt

else()
     list(APPEND abi_properties "no_new_in_libcxx")
   endif()
 
   list(JOIN abi_properties "." tmp)
   set(${result} "${tmp}" PARENT_SCOPE)
 endfunction()
 
 cxx_abi_list_identifier(abi_list_identifier
-  "${LIBCXX_TARGET_TRIPLE}"
+  "${CMAKE_CXX_COMPILER_TARGET}"
   "${LIBCXX_CXX_ABI_LIBNAME}"
   "${LIBCXX_ABI_VERSION}"
   "${LIBCXX_ABI_UNSTABLE}"
   "${LIBCXX_ENABLE_EXCEPTIONS}"
   "${LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS}"
 )
 
 if (TARGET cxx_shared)

libcxx/test/CMakeLists.txt

 if (NOT LIBCXX_ENABLE_RTTI)
   serialize_lit_param(enable_rtti False)
 endif()
 
 if (NOT LIBCXX_ENABLE_DEBUG_MODE_SUPPORT)
   serialize_lit_param(enable_debug_tests False)
 endif()
 
-if (LIBCXX_TARGET_TRIPLE)
-  serialize_lit_param(target_triple "\"${LIBCXX_TARGET_TRIPLE}\"")
+if (CMAKE_CXX_COMPILER_TARGET)
+  serialize_lit_param(target_triple "\"${CMAKE_CXX_COMPILER_TARGET}\"")
 endif()
 
 if (LLVM_USE_SANITIZER)
   serialize_lit_param(use_sanitizer "\"${LLVM_USE_SANITIZER}\"")
 endif()
 
 if (LIBCXX_BUILD_32_BITS)
   serialize_lit_param(enable_32bit True)

libcxx/test/configs/legacy.cfg.in

 config.libcxx_src_root          = "@LIBCXX_SOURCE_DIR@"
 config.libcxx_obj_root          = "@LIBCXX_BINARY_DIR@"
 config.cxx_library_root         = "@LIBCXX_LIBRARY_DIR@"
 config.abi_library_root         = "@LIBCXX_CXX_ABI_LIBRARY_PATH@"
 config.enable_shared            = @LIBCXX_LINK_TESTS_WITH_SHARED_LIBCXX@
 config.cxx_abi                  = "@LIBCXX_CXX_ABI_LIBNAME@"
 config.configuration_variant    = "@LIBCXX_LIT_VARIANT@"
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
-config.sysroot                  = "@LIBCXX_SYSROOT@"
-config.gcc_toolchain            = "@LIBCXX_GCC_TOOLCHAIN@"
+config.sysroot                  = "@CMAKE_SYSROOT@"
+config.gcc_toolchain            = "@CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN@"
 config.generate_coverage        = @LIBCXX_GENERATE_COVERAGE@
 config.target_info              = "@LIBCXX_TARGET_INFO@"
 config.test_linker_flags        = "@LIBCXX_TEST_LINKER_FLAGS@"
 config.test_compiler_flags      = "@LIBCXX_TEST_COMPILER_FLAGS@"
 
 config.executor                 = "@LIBCXX_EXECUTOR@"
 config.llvm_unwinder            = @LIBCXXABI_USE_LLVM_UNWINDER@
 config.builtins_library         = "@LIBCXX_BUILTINS_LIBRARY@"

libcxxabi/CMakeLists.txt

option(LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS
   "Build libc++abi with definitions for operator new/delete. These are normally
    defined in libc++abi, but it is also possible to define them in libc++, in
    which case the definition in libc++abi should be turned off." ON)
 option(LIBCXXABI_BUILD_32_BITS "Build 32 bit libc++abi." ${LLVM_BUILD_32_BITS})
 option(LIBCXXABI_INCLUDE_TESTS "Generate build targets for the libc++abi unit tests." ${LLVM_INCLUDE_TESTS})
 set(LIBCXXABI_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
     "Define suffix of library directory name (32/64)")
 option(LIBCXXABI_INSTALL_LIBRARY "Install the libc++abi library." ON)
-set(LIBCXXABI_TARGET_TRIPLE "${LLVM_DEFAULT_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.")
 set(LIBCXXABI_LIBRARY_VERSION "1.0" CACHE STRING
 "Version of libc++abi. This will be reflected in the name of the shared \
 library produced. For example, -DLIBCXXABI_LIBRARY_VERSION=x.y will \
 result in the library being named libc++abi.x.y.dylib, along with the \
 usual symlinks pointing to that.")
 
 # Default to building a shared library so that the default options still test

 
 #===============================================================================
 # Setup Compiler Flags
 #===============================================================================
 
 # Configure target flags
 add_target_flags_if(LIBCXXABI_BUILD_32_BITS "-m32")
 
-if(LIBCXXABI_TARGET_TRIPLE)
-  add_target_flags_if_supported("--target=${LIBCXXABI_TARGET_TRIPLE}")
-elseif(CMAKE_CXX_COMPILER_TARGET)
-  set(LIBCXXABI_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
-endif()
-if(LIBCXX_GCC_TOOLCHAIN)
-  add_target_flags_if_supported("--gcc-toolchain=${LIBCXXABI_GCC_TOOLCHAIN}")
-elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
-  set(LIBCXXABI_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
-endif()
-if(LIBCXXABI_SYSROOT)
-  add_target_flags_if_supported("--sysroot=${LIBCXXABI_SYSROOT}")
-elseif(CMAKE_SYSROOT)
-  set(LIBCXXABI_SYSROOT "${CMAKE_SYSROOT}")
-endif()
-
 # Configure compiler. Must happen after setting the target flags.
 include(config-ix)
 
 if (LIBCXXABI_HAS_NOSTDINCXX_FLAG)
   list(APPEND LIBCXXABI_COMPILE_FLAGS -nostdinc++)
   # cmake 3.14 and above remove system include paths that are explicitly
   # passed on the command line.  We build with -nostdinc++ and explicitly add
   # just the libcxx system include paths with -I on the command line.

libcxxabi/test/CMakeLists.txt

 endif()
 
 serialize_lit_param(enable_experimental False)
 
 if (LLVM_USE_SANITIZER)
   serialize_lit_param(use_sanitizer "\"${LLVM_USE_SANITIZER}\"")
 endif()
 
-if (LIBCXXABI_TARGET_TRIPLE)
-  serialize_lit_param(target_triple "\"${LIBCXXABI_TARGET_TRIPLE}\"")
+if (CMAKE_CXX_COMPILER_TARGET)
+  serialize_lit_param(target_triple "\"${CMAKE_CXX_COMPILER_TARGET}\"")
 endif()
 
 if (LIBCXXABI_BUILD_32_BITS)
   serialize_lit_param(enable_32bit True)
 endif()
 
 foreach(param IN LISTS LIBCXXABI_TEST_PARAMS)
   string(REGEX REPLACE "(.+)=(.+)" "\\1" name "${param}")

libcxxabi/test/lit.site.cfg.in

 config.llvm_unwinder            = @LIBCXXABI_USE_LLVM_UNWINDER@
 config.builtins_library         = "@LIBCXXABI_BUILTINS_LIBRARY@"
 config.enable_threads           = @LIBCXXABI_ENABLE_THREADS@
 config.target_info              = "@LIBCXXABI_TARGET_INFO@"
 config.executor                 = "@LIBCXXABI_EXECUTOR@"
 config.libcxxabi_shared         = @LIBCXXABI_LINK_TESTS_WITH_SHARED_LIBCXXABI@
 config.enable_shared            = @LIBCXXABI_LINK_TESTS_WITH_SHARED_LIBCXX@
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
-config.sysroot                  = "@LIBCXXABI_SYSROOT@"
-config.gcc_toolchain            = "@LIBCXXABI_GCC_TOOLCHAIN@"
+config.sysroot                  = "@CMAKE_SYSROOT@"
+config.gcc_toolchain            = "@CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN@"
 config.cxx_ext_threads          = @LIBCXXABI_BUILD_EXTERNAL_THREAD_LIBRARY@
 
 config.pstl_src_root            = "@ParallelSTL_SOURCE_DIR@" if @LIBCXX_ENABLE_PARALLEL_ALGORITHMS@ else None
 config.pstl_obj_root            = "@ParallelSTL_BINARY_DIR@" if @LIBCXX_ENABLE_PARALLEL_ALGORITHMS@ else None
 
 # Code signing
 config.llvm_codesign_identity   = "@LLVM_CODESIGNING_IDENTITY@"
 

libunwind/CMakeLists.txt

set(LIBUNWIND_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
     "Define suffix of library directory name (32/64)")
 option(LIBUNWIND_INSTALL_LIBRARY "Install the libunwind library." ON)
 cmake_dependent_option(LIBUNWIND_INSTALL_STATIC_LIBRARY
   "Install the static libunwind library." ON
   "LIBUNWIND_ENABLE_STATIC;LIBUNWIND_INSTALL_LIBRARY" OFF)
 cmake_dependent_option(LIBUNWIND_INSTALL_SHARED_LIBRARY
   "Install the shared libunwind library." ON
   "LIBUNWIND_ENABLE_SHARED;LIBUNWIND_INSTALL_LIBRARY" OFF)
-set(LIBUNWIND_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Target triple for cross compiling.")
-set(LIBUNWIND_GCC_TOOLCHAIN "" CACHE PATH "GCC toolchain for cross compiling.")
-set(LIBUNWIND_SYSROOT "" CACHE PATH "Sysroot for cross compiling.")
 set(LIBUNWIND_TEST_LINKER_FLAGS "" CACHE STRING
     "Additional linker flags for test programs.")
 set(LIBUNWIND_TEST_COMPILER_FLAGS "" CACHE STRING
     "Additional compiler flags for test programs.")
 
 if (LIBUNWIND_ENABLE_SHARED)
   set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-shared.cfg.in")
 else()

 
 #===============================================================================
 # Setup Compiler Flags
 #===============================================================================
 
 # Get required flags.
 add_target_flags_if(LIBUNWIND_BUILD_32_BITS "-m32")
 
-if(LIBUNWIND_TARGET_TRIPLE)
-  add_target_flags_if_supported("--target=${LIBUNWIND_TARGET_TRIPLE}")
-elseif(CMAKE_CXX_COMPILER_TARGET)
-  set(LIBUNWIND_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
-endif()
-if(LIBUNWIND_GCC_TOOLCHAIN)
-  add_target_flags_if_supported("--gcc-toolchain=${LIBUNWIND_GCC_TOOLCHAIN}")
-elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
-  set(LIBUNWIND_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
-endif()
-if(LIBUNWIND_SYSROOT)
-  add_target_flags_if_supported("--sysroot=${LIBUNWIND_SYSROOT}")
-elseif(CMAKE_SYSROOT)
-  set(LIBUNWIND_SYSROOT "${CMAKE_SYSROOT}")
-endif()
-
 # Configure compiler.
 include(config-ix)
 
 if (LIBUNWIND_USE_COMPILER_RT AND NOT LIBUNWIND_HAS_NODEFAULTLIBS_FLAG)
   list(APPEND LIBUNWIND_LINK_FLAGS "-rtlib=compiler-rt")
 endif()
 
 add_compile_flags_if_supported(-Werror=return-type)

libunwind/docs/BuildingLibunwind.rst

.. option:: LIBUNWIND_ENABLE_ARM_WMMX:BOOL
   Enable unwinding support for ARM WMMX registers.
 
 .. option:: LIBUNWIND_ENABLE_THREADS:BOOL
 
   **Default**: ``ON``
 
   Build libunwind with threading support.
 
-.. option:: LIBUNWIND_TARGET_TRIPLE:STRING
-
-  Target triple for cross compiling
-
-.. option:: LIBUNWIND_GCC_TOOLCHAIN:PATH
-
-  GCC toolchain for cross compiling
-
-.. option:: LIBUNWIND_SYSROOT
-
-  Sysroot for cross compiling
-
 .. option:: LIBUNWIND_INSTALL_LIBRARY_DIR:PATH
 
   **Default**: ``lib${LIBUNWIND_LIBDIR_SUFFIX}``
 
   Path where built libunwind libraries should be installed. If a relative path,
   relative to ``CMAKE_INSTALL_PREFIX``.

libunwind/test/CMakeLists.txt

 endmacro()
 
 serialize_lit_param(enable_experimental False)
 
 if (LLVM_USE_SANITIZER)
   serialize_lit_param(use_sanitizer "\"${LLVM_USE_SANITIZER}\"")
 endif()
 
-if (LIBUNWIND_TARGET_TRIPLE)
-  serialize_lit_param(target_triple "\"${LIBUNWIND_TARGET_TRIPLE}\"")
+if (CMAKE_CXX_COMPILER_TARGET)
+  serialize_lit_param(target_triple "\"${CMAKE_CXX_COMPILER_TARGET}\"")
 endif()
 
 if (LIBUNWIND_BUILD_32_BITS)
   serialize_lit_param(enable_32bit True)
 endif()
 
 foreach(param IN LISTS LIBUNWIND_TEST_PARAMS)
   string(REGEX REPLACE "(.+)=(.+)" "\\1" name "${param}")

libunwind/test/lit.site.cfg.in

 config.target_info              = "@LIBUNWIND_TARGET_INFO@"
 config.test_linker_flags        = "@LIBUNWIND_TEST_LINKER_FLAGS@"
 config.test_compiler_flags      = "@LIBUNWIND_TEST_COMPILER_FLAGS@"
 config.executor                 = "@LIBUNWIND_EXECUTOR@"
 config.libunwind_shared         = @LIBUNWIND_ENABLE_SHARED@
 config.enable_shared            = @LIBCXX_ENABLE_SHARED@
 config.arm_ehabi                = @LIBUNWIND_USES_ARM_EHABI@
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
-config.sysroot                  = "@LIBUNWIND_SYSROOT@"
-config.gcc_toolchain            = "@LIBUNWIND_GCC_TOOLCHAIN@"
+config.sysroot                  = "@CMAKE_SYSROOT@"
+config.gcc_toolchain            = "@CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN@"
 config.cxx_ext_threads          = @LIBUNWIND_BUILD_EXTERNAL_THREAD_LIBRARY@
 config.x86_cet                  = @LIBUNWIND_ENABLE_CET@
 
 site.addsitedir(os.path.join(config.libunwind_src_root, 'test'))
 site.addsitedir(os.path.join(config.libcxx_src_root, 'utils'))
 
 # name: The name of this test suite.
 config.name = 'libunwind'