[OpenMP] Refactor CMake files related to `PluginInterface` in `plugins-nextgen`

[tianshilei1992]

Summary

This patch uses refactors CMake files related to PluginInterface in plugins-nextgen to handle LLVM dependences in a better way.

[jhuber6]

openmp/libomptarget/plugins-nextgen/common/PluginInterface/CMakeLists.txt

15

Should these be tied to the target rather than global?

[tianshilei1992]

fix comments

[tianshilei1992]

fix style

[lebedev.ri]

I've reverted this since it broke cmake regeneration for me

CMake Error: install(EXPORT "LLVMExports" ...) includes target "omptarget.rtl.cuda.nextgen" which requires target "PluginInterface" that is not in any export set.
CMake Error: install(EXPORT "LLVMExports" ...) includes target "omptarget.rtl.x86_64.nextgen" which requires target "PluginInterface" that is not in any export set.

[tianshilei1992]

In D139371#3972748, @lebedev.ri wrote:

I've reverted this since it broke cmake regeneration for me

CMake Error: install(EXPORT "LLVMExports" ...) includes target "omptarget.rtl.cuda.nextgen" which requires target "PluginInterface" that is not in any export set.
CMake Error: install(EXPORT "LLVMExports" ...) includes target "omptarget.rtl.x86_64.nextgen" which requires target "PluginInterface" that is not in any export set.

Thanks. Will fix it.

[tianshilei1992]

fix configure error

[lebedev.ri]

Still not quite there, aa6ea6009fc50b02dbf3788ee9fe605081b154f6.

[tianshilei1992]

gave up using add_llvm_library

[tianshilei1992]

This comment was removed by tianshilei1992.

[lebedev.ri]

Did you succeed in reproducing the problem?

[tianshilei1992]

In D139371#3975659, @lebedev.ri wrote:

Did you succeed in reproducing the problem?

Yes, and the updated version should fix the problem on your side. Can you try it locally to see if the problem is gone?

[lebedev.ri]

In D139371#3975720, @tianshilei1992 wrote:

In D139371#3975659, @lebedev.ri wrote:

Did you succeed in reproducing the problem?

Yes, and the updated version should fix the problem on your side. Can you try it locally to see if the problem is gone?

If you are sure that you've reproduced the problem and then it got fixed, then please feel free to go ahead.

openmp/libomptarget/plugins-nextgen/common/PluginInterface/CMakeLists.txt

 ##===----------------------------------------------------------------------===##
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 ##===----------------------------------------------------------------------===##
 #
 # Common parts which can be used by all plugins
 #
 ##===----------------------------------------------------------------------===##
 
-# Plugin Interface library.
+# NOTE: Don't try to build `PluginInterface` using `add_llvm_library` because we
+# don't want to export `PluginInterface` while `add_llvm_library` requires that.
 add_library(PluginInterface OBJECT PluginInterface.cpp GlobalHandler.cpp)
 
-# Define the TARGET_NAME.
-add_definitions("-DTARGET_NAME=PluginInterface")
+# This is required when using LLVM libraries.
+llvm_update_compile_flags(PluginInterface)
+
+if (LLVM_LINK_LLVM_DYLIB)
+  set(llvm_libs LLVM)
+else()
+  llvm_map_components_to_libnames(llvm_libs Support)
+endif()
+
+target_link_libraries(PluginInterface
+  PUBLIC
+    ${llvm_libs}
+    elf_common
+    MemoryManager
+)
 
-# Define the DEBUG_PREFIX.
-add_definitions(-DDEBUG_PREFIX="PluginInterface")
+# Define the TARGET_NAME and DEBUG_PREFIX.
+target_compile_definitions(PluginInterface PRIVATE
+  TARGET_NAME="PluginInterface"
+  DEBUG_PREFIX="PluginInterface"
+)
+
+target_include_directories(PluginInterface
+  INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+  PRIVATE ${LIBOMPTARGET_INCLUDE_DIR}
+)
 
 set_target_properties(PluginInterface PROPERTIES
   POSITION_INDEPENDENT_CODE ON
   CXX_VISIBILITY_PRESET protected)
-llvm_update_compile_flags(PluginInterface)
-set(LINK_LLVM_LIBS LLVMSupport)
-if (LLVM_LINK_LLVM_DYLIB)
-  set(LINK_LLVM_LIBS LLVM)
-endif()
-target_link_libraries(PluginInterface INTERFACE ${LINK_LLVM_LIBS} PRIVATE elf_common MemoryManager)
-add_dependencies(PluginInterface ${LINK_LLVM_LIBS})
-
-target_include_directories(PluginInterface INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
-target_include_directories(PluginInterface PRIVATE ${LIBOMPTARGET_INCLUDE_DIR})

openmp/libomptarget/plugins/common/elf_common/CMakeLists.txt

 ##===----------------------------------------------------------------------===##
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 ##===----------------------------------------------------------------------===##
 #
 # Common ELF functionality for target plugins
 #
 ##===----------------------------------------------------------------------===##
 
+# NOTE: Don't try to build `elf_common` using `add_llvm_library`.
+# See openmp/libomptarget/plugins-nextgen/common/PluginInterface/CMakeLists.txt
+# for more explanation.
 add_library(elf_common OBJECT elf_common.cpp ELFSymbols.cpp)
 
-# Build elf_common with PIC to be able to link it with plugin shared libraries.
-set_property(TARGET elf_common PROPERTY POSITION_INDEPENDENT_CODE ON)
+# This is required when using LLVM libraries.
 llvm_update_compile_flags(elf_common)
-set(LINK_LLVM_LIBS LLVMBinaryFormat LLVMObject LLVMSupport)
+
 if (LLVM_LINK_LLVM_DYLIB)
-  set(LINK_LLVM_LIBS LLVM)
+  set(llvm_libs LLVM)
+else()
+  llvm_map_components_to_libnames(llvm_libs BinaryFormat Object Support)
 endif()
-target_link_libraries(elf_common INTERFACE ${LINK_LLVM_LIBS})
-add_dependencies(elf_common ${LINK_LLVM_LIBS})
 
-# The code uses Debug.h, which requires threads support.
-target_link_libraries(elf_common INTERFACE ${OPENMP_PTHREAD_LIB})
+target_link_libraries(elf_common PUBLIC ${llvm_libs} ${OPENMP_PTHREAD_LIB})
+
+# Build elf_common with PIC to be able to link it with plugin shared libraries.
+set_property(TARGET elf_common PROPERTY POSITION_INDEPENDENT_CODE ON)
 
 # Expose elf_common.h directory to the users of this library.
-target_include_directories(elf_common INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
-target_include_directories(elf_common PRIVATE ${LIBOMPTARGET_INCLUDE_DIR})
+target_include_directories(elf_common
+  INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+  PRIVATE ${LIBOMPTARGET_INCLUDE_DIR}
+)