[libomptarget][NFC] Link plugins with threads support library due to std::call_once usage.

[vzakhari]

Summary

The title is self-descriptive. There are some details here: https://reviews.llvm.org/D93727#2524458

I was going to assert that the threads support library is found in openmp/libomptarget/cmake/Modules/LibomptargetGetDependencies.cmake, but I guess there may be plugins that do not use Debug.h, so I left it undefined what happens, if the library is not found.

[jdoerfert]

This is not NFC but other than that reasonable. LG, @grokos ?

[grokos]

I've tested the change and everything seems to work fine. So let's commit it. Thanks for the patch!

[jdoerfert]

In D95572#2527005, @grokos wrote:

I've tested the change and everything seems to work fine. So let's commit it. Thanks for the patch!

We need to backport this to 12, right?

[grokos]

In D95572#2527063, @jdoerfert wrote:

We need to backport this to 12, right?

I guess so. Otherwise users may get failures that are really hard to explain...

[vzakhari]

In D95572#2527005, @grokos wrote:

I've tested the change and everything seems to work fine. So let's commit it. Thanks for the patch!

Do you mean I can ignore the pre-merge checks fail? I do not see how my changes could have affected libomp build.

[jdoerfert]

In D95572#2527082, @vzakhari wrote:

In D95572#2527005, @grokos wrote:

I've tested the change and everything seems to work fine. So let's commit it. Thanks for the patch!

Do you mean I can ignore the pre-merge checks fail? I do not see how my changes could have affected libomp build.

looks to me like that is the C++ dependence problem we discussed this morning. I don't think this patch caused it so I would go ahead.

[vzakhari]

In D95572#2527083, @jdoerfert wrote:

In D95572#2527082, @vzakhari wrote:

In D95572#2527005, @grokos wrote:

I've tested the change and everything seems to work fine. So let's commit it. Thanks for the patch!

Do you mean I can ignore the pre-merge checks fail? I do not see how my changes could have affected libomp build.

looks to me like that is the C++ dependence problem we discussed this morning. I don't think this patch caused it so I would go ahead.

Thank you! Merged.

openmp/libomptarget/cmake/Modules/LibomptargetGetDependencies.cmake

if (LSB_RELEASE)
     set(candidate_dir /usr/lib/cuda)
     if ((LSB_RELEASE_ID STREQUAL "Debian" OR LSB_RELEASE_ID STREQUAL "Ubuntu")
         AND EXISTS "${candidate_dir}/${LIBOMPTARGET_CUDA_LIBDEVICE_SUBDIR}")
       set(CUDA_TOOLKIT_ROOT_DIR "${candidate_dir}" CACHE PATH
           "Toolkit location." FORCE)
     endif()
   endif()
 endif()
+
+if (OPENMP_STANDALONE_BUILD)
+  # This duplicates code from llvm/cmake/config-ix.cmake
+  if( WIN32 AND NOT CYGWIN )
+    # We consider Cygwin as another Unix
+    set(PURE_WINDOWS 1)
+  endif()
+
+  # library checks
+  if( NOT PURE_WINDOWS )
+    check_library_exists(pthread pthread_create "" HAVE_LIBPTHREAD)
+  endif()
+
+  if(HAVE_LIBPTHREAD)
+    # We want to find pthreads library and at the moment we do want to
+    # have it reported as '-l<lib>' instead of '-pthread'.
+    # TODO: switch to -pthread once the rest of the build system can deal with it.
+    set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
+    set(THREADS_HAVE_PTHREAD_ARG Off)
+    find_package(Threads REQUIRED)
+    set(OPENMP_PTHREAD_LIB ${CMAKE_THREAD_LIBS_INIT})
+  endif()
+else()
+  set(OPENMP_PTHREAD_LIB ${LLVM_PTHREAD_LIB})
+endif()

openmp/libomptarget/plugins/CMakeLists.txt

if(LIBOMPTARGET_DEP_LIBFFI_FOUND)
         LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
 
       target_link_libraries(
         "omptarget.rtl.${tmachine_libname}"
         elf_common
         ${LIBOMPTARGET_DEP_LIBFFI_LIBRARIES}
         ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
         dl
+        ${OPENMP_PTHREAD_LIB}
         "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports")
 
       list(APPEND LIBOMPTARGET_TESTED_PLUGINS
         "omptarget.rtl.${tmachine_libname}")
 
       # Report to the parent scope that we are building a plugin.
       set(LIBOMPTARGET_SYSTEM_TARGETS
         "${LIBOMPTARGET_SYSTEM_TARGETS} ${tmachine_triple}" PARENT_SCOPE)

openmp/libomptarget/plugins/cuda/CMakeLists.txt

 # Install plugin under the lib destination folder.
 install(TARGETS omptarget.rtl.cuda LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
 
 target_link_libraries(omptarget.rtl.cuda
   elf_common
   MemoryManager
   ${LIBOMPTARGET_DEP_LIBRARIES}
   ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
+  ${OPENMP_PTHREAD_LIB}
   "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports"
   "-Wl,-z,defs")
 
 # Report to the parent scope that we are building a plugin for CUDA.
 # This controls whether tests are run for the nvptx offloading target
 # Run them if libcuda is available, or if the user explicitly asked for dlopen
 # Otherwise this plugin is being built speculatively and there may be no cuda available
 if (LIBOMPTARGET_CAN_LINK_LIBCUDA OR LIBOMPTARGET_FORCE_DLOPEN_LIBCUDA)
   libomptarget_say("Enable tests using CUDA plugin")
   set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS} nvptx64-nvidia-cuda" PARENT_SCOPE)
 else()
   libomptarget_say("Disabling tests using CUDA plugin as cuda may not be available")
 endif()

openmp/libomptarget/plugins/remote/server/CMakeLists.txt

add_executable(openmp-offloading-server
         ${RPC_SRC_DIR}/Utils.cpp
         Server.cpp
         OffloadingServer.cpp
 )
 
 target_link_libraries(openmp-offloading-server
         grpc++
         protobuf
+        ${OPENMP_PTHREAD_LIB}
         "-ldl" "-lomp" "-fopenmp" "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../../exports" ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES})

openmp/libomptarget/plugins/remote/src/CMakeLists.txt

 
 # Install plugin under the lib destination folder.
 install(TARGETS omptarget.rtl.rpc LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
 
 target_link_libraries(omptarget.rtl.rpc
   grpc++
   protobuf
   "-ldl"
+  ${OPENMP_PTHREAD_LIB}
   "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../../exports")
 
 # Report to the parent scope that we are building a plugin for RPC.
 set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS} rpc" PARENT_SCOPE)