[CMake][NFC] Clean up CheckAtomic.cmake

`CheckAtomic.cmake` was skipping the test of whether atomics work in MSVC
without an atomics library (they do), but not setting the value of
`HAVE_CXX_ATOMICS_WITHOUT_LIB`. That caused build issues when trying to land
D69869. I fixed that issue in f128f442a3d, by adding an `elseif(MSVC)`, as
was being done below in the 64-bit atomics check. That minimal fix did work,
but it kept various inconsistencies between the original atomics check and
the 64-bit one. This patch now makes the checks follow the same structure,
cleaning them up.

Differential Revision: https://reviews.llvm.org/D74767
This commit is contained in:
Luís Marques 2020-04-18 12:51:25 +01:00
parent bdf641f815
commit b634f6f189

View File

@ -39,46 +39,45 @@ int main() {
endfunction(check_working_cxx_atomics64)
# This isn't necessary on MSVC, so avoid command-line switch annoyance
# by only running on GCC-like hosts.
if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
# Check for (non-64-bit) atomic operations.
if(MSVC)
set(HAVE_CXX_ATOMICS_WITHOUT_LIB True)
elseif(LLVM_COMPILER_IS_GCC_COMPATIBLE)
# First check if atomics work without the library.
check_working_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_4 "" HAVE_LIBATOMIC)
if( HAVE_LIBATOMIC )
if(HAVE_LIBATOMIC)
list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
check_working_cxx_atomics(HAVE_CXX_ATOMICS_WITH_LIB)
if (NOT HAVE_CXX_ATOMICS_WITH_LIB)
message(FATAL_ERROR "Host compiler must support std::atomic!")
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()
elseif(MSVC)
set(HAVE_CXX_ATOMICS_WITHOUT_LIB True)
endif()
# Check for 64 bit atomic operations.
if(MSVC)
set(HAVE_CXX_ATOMICS64_WITHOUT_LIB True)
else()
elseif(LLVM_COMPILER_IS_GCC_COMPATIBLE)
# First check if atomics work without the library.
check_working_cxx_atomics64(HAVE_CXX_ATOMICS64_WITHOUT_LIB)
endif()
# If not, check if the library exists, and atomics work with it.
if(NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB)
check_library_exists(atomic __atomic_load_8 "" HAVE_CXX_LIBATOMICS64)
if(HAVE_CXX_LIBATOMICS64)
list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
check_working_cxx_atomics64(HAVE_CXX_ATOMICS64_WITH_LIB)
if (NOT HAVE_CXX_ATOMICS64_WITH_LIB)
message(FATAL_ERROR "Host compiler must support 64-bit std::atomic!")
# If not, check if the library exists, and atomics work with it.
if(NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB)
check_library_exists(atomic __atomic_load_8 "" HAVE_CXX_LIBATOMICS64)
if(HAVE_CXX_LIBATOMICS64)
list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
check_working_cxx_atomics64(HAVE_CXX_ATOMICS64_WITH_LIB)
if (NOT HAVE_CXX_ATOMICS64_WITH_LIB)
message(FATAL_ERROR "Host compiler must support 64-bit std::atomic!")
endif()
else()
message(FATAL_ERROR "Host compiler appears to require libatomic for 64-bit operations, but cannot find it.")
endif()
else()
message(FATAL_ERROR "Host compiler appears to require libatomic for 64-bit operations, but cannot find it.")
endif()
endif()