[libcxx] r260235 - Introduce a cmake module to figure out whether we need to link with libatomic.
Eric Fiselier via cfe-commits
cfe-commits at lists.llvm.org
Thu Feb 11 08:08:25 PST 2016
> we need to rename HAVE_CXX_ATOMICS_WITH_LIB to something like
LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB.
Fixed in r260531.
I think we will eventually want to merge the following commits, assuming
they don't regress the build, especially with the -gcc-toolchain option.
- [libcxx] r260515 - Re-commit "Introduce a cmake module to figure out
whether we need to link with libatomic."
- [libcxx] r260524 - Fix r260515 - Correct typos in CMake changes
- [libcxx] r260531 - Rename CheckLibcxxAtomic.cmake variable result names
so they don't clash with LLVM
@Marshall Any objections?
On Thu, Feb 11, 2016 at 2:18 AM, Daniel Sanders via cfe-commits <
cfe-commits at lists.llvm.org> wrote:
> Hi,
>
> In my latests rc2+patches build I've also found that we need to rename
> HAVE_CXX_ATOMICS_WITH_LIB to something like
> LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB. It's currently re-using the result of
> LLVM's check which doesn't include 64-bit atomics.
> ________________________________________
> From: Vasileios Kalintiris
> Sent: 09 February 2016 23:50
> To: hans at chromium.org
> Cc: cfe-commits at lists.llvm.org; Daniel Sanders; mclow.lists at gmail.com
> Subject: RE: [libcxx] r260235 - Introduce a cmake module to figure out
> whether we need to link with libatomic.
>
> Hi Hans,
>
> Please wait before merging this as it breaks LLVM bootstraps when using
> the -gcc-toolchain option and the system's default gcc installation does
> not provide libatomic. We have to check LIBCXX_GCC_TOOLCHAIN in our test.
> I'll create a patch tomorrow and I'll let you know when it's okay to merge
> them. In the meantime, I reverted it in r260323.
>
> - Vasileios
> ________________________________________
> From: Vasileios Kalintiris
> Sent: 09 February 2016 18:56
> To: hans at chromium.org
> Cc: cfe-commits at lists.llvm.org; Daniel Sanders; mclow.lists at gmail.com
> Subject: RE: [libcxx] r260235 - Introduce a cmake module to figure out
> whether we need to link with libatomic.
>
> Hi Hans,
>
> Can we merge this on the 3.8 release branch? It fixes libcxx builds on
> MIPS by linking with libatomic when needed. Also, all the x86_64 and ARM
> buildbots for libcxx look good.
>
> Thanks,
> Vasileios
>
> ________________________________________
> From: cfe-commits [cfe-commits-bounces at lists.llvm.org] on behalf of
> Vasileios Kalintiris via cfe-commits [cfe-commits at lists.llvm.org]
> Sent: 09 February 2016 17:00
> To: cfe-commits at lists.llvm.org
> Subject: [libcxx] r260235 - Introduce a cmake module to figure out whether
> we need to link with libatomic.
>
> Author: vkalintiris
> Date: Tue Feb 9 11:00:38 2016
> New Revision: 260235
>
> URL: http://llvm.org/viewvc/llvm-project?rev=260235&view=rev
> Log:
> Introduce a cmake module to figure out whether we need to link with
> libatomic.
>
> Summary:
> This fixes the tests under std/atomics for 32-bit MIPS CPUs where the
> 8-byte atomic operations call into the libatomic library.
>
> Reviewers: dsanders, mclow.lists, EricWF, jroelofs, joerg
>
> Subscribers: cfe-commits
>
> Differential Revision: http://reviews.llvm.org/D16613
>
> Added:
> libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake
> Modified:
> libcxx/trunk/cmake/config-ix.cmake
> libcxx/trunk/lib/CMakeLists.txt
> libcxx/trunk/test/CMakeLists.txt
> libcxx/trunk/test/libcxx/test/target_info.py
> libcxx/trunk/test/lit.site.cfg.in
>
> Added: libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake?rev=260235&view=auto
>
> ==============================================================================
> --- libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake (added)
> +++ libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake Tue Feb 9 11:00:38
> 2016
> @@ -0,0 +1,38 @@
> +INCLUDE(CheckCXXSourceCompiles)
> +
> +# Sometimes linking against libatomic is required for atomic ops, if
> +# the platform doesn't support lock-free atomics.
> +#
> +# We could modify LLVM's CheckAtomic module and have it check for 64-bit
> +# atomics instead. However, we would like to avoid careless uses of 64-bit
> +# atomics inside LLVM over time on 32-bit platforms.
> +
> +function(check_cxx_atomics varname)
> + set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
> + set(CMAKE_REQUIRED_FLAGS "-std=c++11")
> + check_cxx_source_compiles("
> +#include <cstdint>
> +#include <atomic>
> +std::atomic<uintptr_t> x;
> +std::atomic<uintmax_t> y;
> +int main() {
> + return x + y;
> +}
> +" ${varname})
> + set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
> +endfunction(check_cxx_atomics)
> +
> +check_cxx_atomics(HAVE_CXX_ATOMICS_WITHOUT_LIB)
> +# If not, check if the library exists, and atomics work with it.
> +if(NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
> + check_library_exists(atomic __atomic_fetch_add_8 "" HAVE_LIBATOMIC)
> + if(HAVE_LIBATOMIC)
> + list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
> + check_cxx_atomics(HAVE_CXX_ATOMICS_WITH_LIB)
> + if (NOT HAVE_CXX_ATOMICS_WITH_LIB)
> + message(FATAL_ERROR "Host compiler must support std::atomic!")
> + endif()
> + else()
> + message(FATAL_ERROR "Host compiler appears to require libatomic, but
> cannot find it.")
> + endif()
> +endif()
>
> Modified: libcxx/trunk/cmake/config-ix.cmake
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/cmake/config-ix.cmake?rev=260235&r1=260234&r2=260235&view=diff
>
> ==============================================================================
> --- libcxx/trunk/cmake/config-ix.cmake (original)
> +++ libcxx/trunk/cmake/config-ix.cmake Tue Feb 9 11:00:38 2016
> @@ -1,5 +1,6 @@
> include(CheckLibraryExists)
> include(CheckCXXCompilerFlag)
> +include(CheckLibcxxAtomic)
>
> # Check compiler flags
>
> @@ -17,3 +18,7 @@ check_library_exists(c fopen "" LIBCXX_H
> check_library_exists(m ccos "" LIBCXX_HAS_M_LIB)
> check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB)
> check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB)
> +
> +if (NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
> + set(LIBCXX_HAS_ATOMIC_LIB True)
> +endif()
>
> Modified: libcxx/trunk/lib/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/lib/CMakeLists.txt?rev=260235&r1=260234&r2=260235&view=diff
>
> ==============================================================================
> --- libcxx/trunk/lib/CMakeLists.txt (original)
> +++ libcxx/trunk/lib/CMakeLists.txt Tue Feb 9 11:00:38 2016
> @@ -79,6 +79,7 @@ add_library_flags_if(LIBCXX_HAS_C_LIB c)
> add_library_flags_if(LIBCXX_HAS_M_LIB m)
> add_library_flags_if(LIBCXX_HAS_RT_LIB rt)
> add_library_flags_if(LIBCXX_HAS_GCC_S_LIB gcc_s)
> +add_library_flags_if(LIBCXX_HAS_ATOMIC_LIB atomic)
>
> # Setup flags.
> add_flags_if_supported(-fPIC)
>
> Modified: libcxx/trunk/test/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/CMakeLists.txt?rev=260235&r1=260234&r2=260235&view=diff
>
> ==============================================================================
> --- libcxx/trunk/test/CMakeLists.txt (original)
> +++ libcxx/trunk/test/CMakeLists.txt Tue Feb 9 11:00:38 2016
> @@ -15,6 +15,7 @@ pythonize_bool(LIBCXX_ENABLE_SHARED)
> pythonize_bool(LIBCXX_BUILD_32_BITS)
> pythonize_bool(LIBCXX_GENERATE_COVERAGE)
> pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
> +pythonize_bool(LIBCXX_HAS_ATOMIC_LIB)
>
> # The tests shouldn't link to any ABI library when it has been linked into
> # libc++ statically or via a linker script.
>
> Modified: libcxx/trunk/test/libcxx/test/target_info.py
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/libcxx/test/target_info.py?rev=260235&r1=260234&r2=260235&view=diff
>
> ==============================================================================
> --- libcxx/trunk/test/libcxx/test/target_info.py (original)
> +++ libcxx/trunk/test/libcxx/test/target_info.py Tue Feb 9 11:00:38 2016
> @@ -172,6 +172,9 @@ class LinuxLocalTI(DefaultTargetInfo):
> flags += ['-lunwind', '-ldl']
> else:
> flags += ['-lgcc_s', '-lgcc']
> + use_libatomic = self.full_config.get_lit_bool('use_libatomic',
> False)
> + if use_libatomic:
> + flags += ['-latomic']
> san = self.full_config.get_lit_conf('use_sanitizer', '').strip()
> if san:
> # The libraries and their order are taken from the
>
> Modified: libcxx/trunk/test/lit.site.cfg.in
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/lit.site.cfg.in?rev=260235&r1=260234&r2=260235&view=diff
>
> ==============================================================================
> --- libcxx/trunk/test/lit.site.cfg.in (original)
> +++ libcxx/trunk/test/lit.site.cfg.in Tue Feb 9 11:00:38 2016
> @@ -20,6 +20,7 @@ config.generate_coverage = "@LIBC
> config.target_info = "@LIBCXX_TARGET_INFO@"
> config.executor = "@LIBCXX_EXECUTOR@"
> config.llvm_unwinder = "@LIBCXXABI_USE_LLVM_UNWINDER@"
> +config.use_libatomic = "@LIBCXX_HAS_ATOMIC_LIB@"
>
> # Let the main config do the real work.
> lit_config.load_config(config, "@LIBCXX_SOURCE_DIR@/test/lit.cfg")
>
>
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