[CMake] Disable building libomptarget and add CMake switch

Introduce OPENMP_ENABLE_LIBOMPTARGET which defaults to OFF at the moment.

libomptarget is not yet ready for prime time:
 - Offloading to NVIDIA GPUs is not completed yet (compiler, device RTL)
 - The generic ELF plugin for offloading to the host (meant for testing)
   uses a single instance of the OpenMP runtime (libomp). That is why
   omp_is_initial_device() returns 1 which makes the tests fail.
Because of these reasons, we want to disable building (and testing!)
for release 5.0.

See https://bugs.llvm.org/show_bug.cgi?id=33859

Differential Revision: https://reviews.llvm.org/D35719

llvm-svn: 309115

diff --git a/openmp/CMakeLists.txt b/openmp/CMakeLists.txt
index a204266..aafba3c 100644 (file)
--- a/openmp/CMakeLists.txt
+++ b/openmp/CMakeLists.txt
@@ -4,9 +4,20 @@ set(OPENMP_LLVM_TOOLS_DIR "" CACHE PATH "Path to LLVM tools for testing")
 
 add_subdirectory(runtime)
 
+
+# The tests currently don't pass if the generic ELF plugin is built.
+# TODO: Fix the tests and enable libomptarget by default on supported
+#       architectures and platforms.
+set(ENABLE_LIBOMPTARGET OFF)
 # Currently libomptarget cannot be compiled on Windows or MacOS X.
 # Since the device plugins are only supported on Linux anyway,
 # there is no point in trying to compile libomptarget on other OSes.
-if (NOT (WIN32 OR ${CMAKE_SYSTEM_NAME} MATCHES "Darwin"))
+if (WIN32 OR ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+  set(ENABLE_LIBOMPTARGET OFF)
+endif()
+
+option(OPENMP_ENABLE_LIBOMPTARGET "Enable building libomptarget for offloading."
+       ${ENABLE_LIBOMPTARGET})
+if (OPENMP_ENABLE_LIBOMPTARGET)
   add_subdirectory(libomptarget)
 endif()