[Libomptarget] Rework interface for enabling plugins

offload/CMakeLists.txt

@@ -151,6 +151,25 @@ if (NOT LIBOMPTARGET_LLVM_INCLUDE_DIRS)
   message(FATAL_ERROR "Missing definition for LIBOMPTARGET_LLVM_INCLUDE_DIRS")
 endif()
 
+set(LIBOMPTARGET_ALL_PLUGIN_TARGETS amdgpu cuda host)
+set(LIBOMPTARGET_PLUGINS_TO_BUILD "all" CACHE STRING
+    "Semicolon-separated list of plugins to use: cuda, amdgpu, host or \"all\".")
+
+if(LIBOMPTARGET_PLUGINS_TO_BUILD STREQUAL "all")
+  set(LIBOMPTARGET_PLUGINS_TO_BUILD ${LIBOMPTARGET_ALL_PLUGIN_TARGETS})
+endif()
+
+set(LIBOMPTARGET_ENUM_PLUGIN_TARGETS "")
+foreach(plugin IN LISTS LIBOMPTARGET_PLUGINS_TO_BUILD)
+  set(LIBOMPTARGET_ENUM_PLUGIN_TARGETS
+      "${LIBOMPTARGET_ENUM_PLUGIN_TARGETS}PLUGIN_TARGET(${plugin})\n")
+endforeach()
+string(STRIP ${LIBOMPTARGET_ENUM_PLUGIN_TARGETS} LIBOMPTARGET_ENUM_PLUGIN_TARGETS)
+configure_file(
+  ${CMAKE_CURRENT_SOURCE_DIR}/include/Shared/Targets.def.in
+  ${CMAKE_CURRENT_BINARY_DIR}/include/Shared/Targets.def
+)
+
 include_directories(${LIBOMPTARGET_LLVM_INCLUDE_DIRS})
 
 # This is a list of all the targets that are supported/tested right now.
@@ -288,6 +307,7 @@ set(LIBOMPTARGET_GPU_LIBC_SUPPORT ${LLVM_LIBC_GPU_BUILD} CACHE BOOL
 pythonize_bool(LIBOMPTARGET_GPU_LIBC_SUPPORT)
 
 set(LIBOMPTARGET_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/include)
+set(LIBOMPTARGET_BINARY_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/include)
 message(STATUS "OpenMP tools dir in libomptarget: ${LIBOMP_OMP_TOOLS_INCLUDE_DIR}")
 if(LIBOMP_OMP_TOOLS_INCLUDE_DIR)
   include_directories(${LIBOMP_OMP_TOOLS_INCLUDE_DIR})

offload/include/Shared/Targets.def.in

@@ -0,0 +1,20 @@
+//===-- Shared/Targets.def - Target plugin enumerator -----------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Enumerates over all of the supported target plugins that are available to
+// the offloading library.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef PLUGIN_TARGET
+#  error Please define the macro PLUGIN_TARGET(TargetName)
+#endif
+
+@LIBOMPTARGET_ENUM_PLUGIN_TARGETS@
+
+#undef PLUGIN_TARGET

offload/plugins-nextgen/CMakeLists.txt

@@ -69,9 +69,12 @@ function(add_target_library target_name lib_name)
   set_target_properties(${target_name} PROPERTIES CXX_VISIBILITY_PRESET protected)
 endfunction()
 
-add_subdirectory(amdgpu)
-add_subdirectory(cuda)
-add_subdirectory(host)
+foreach(plugin IN LISTS LIBOMPTARGET_PLUGINS_TO_BUILD)
+  if(NOT EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${plugin})
+    message(FATAL_ERROR "Unknown plugin target '${plugin}'")
+  endif()
+  add_subdirectory(${plugin})
+endforeach()
 
 # Make sure the parent scope can see the plugins that will be created.
 set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS}" PARENT_SCOPE)

offload/plugins-nextgen/common/CMakeLists.txt

@@ -62,6 +62,7 @@ target_link_options(PluginCommon PUBLIC ${offload_link_flags})
 target_include_directories(PluginCommon PUBLIC 
   ${CMAKE_CURRENT_SOURCE_DIR}/include
   ${LIBOMPTARGET_LLVM_INCLUDE_DIRS}
+  ${LIBOMPTARGET_BINARY_INCLUDE_DIR}
   ${LIBOMPTARGET_INCLUDE_DIR}
 )
 

offload/src/CMakeLists.txt

@@ -37,6 +37,7 @@ add_llvm_library(omptarget
 
   ADDITIONAL_HEADER_DIRS
   ${LIBOMPTARGET_INCLUDE_DIR}
+  ${LIBOMPTARGET_BINARY_INCLUDE_DIR}
 
   LINK_COMPONENTS
   Support
@@ -49,7 +50,9 @@ add_llvm_library(omptarget
   NO_INSTALL_RPATH
   BUILDTREE_ONLY
 )
-target_include_directories(omptarget PRIVATE ${LIBOMPTARGET_INCLUDE_DIR})
+target_include_directories(omptarget PRIVATE 
+  ${LIBOMPTARGET_INCLUDE_DIR} ${LIBOMPTARGET_BINARY_INCLUDE_DIR}
+)
 
 if (LIBOMP_HAVE_VERSION_SCRIPT_FLAG)
   target_link_libraries(omptarget PRIVATE
@@ -65,20 +68,6 @@ target_compile_definitions(omptarget PRIVATE
 target_compile_options(omptarget PUBLIC ${offload_compile_flags})
 target_link_options(omptarget PUBLIC ${offload_link_flags})
 
-macro(check_plugin_target target)
-if (TARGET omptarget.rtl.${target})
-	list(APPEND LIBOMPTARGET_PLUGINS_TO_LOAD ${target})
-endif()
-endmacro()
-
-set(LIBOMPTARGET_PLUGINS_TO_LOAD "" CACHE STRING
-  "Comma separated list of plugin names to look for at runtime")
-if (NOT LIBOMPTARGET_PLUGINS_TO_LOAD)
-	check_plugin_target(cuda)
-	check_plugin_target(amdgpu)
-	check_plugin_target(host)
-endif()
-
 list(TRANSFORM LIBOMPTARGET_PLUGINS_TO_LOAD PREPEND "\"libomptarget.rtl.")
 list(TRANSFORM LIBOMPTARGET_PLUGINS_TO_LOAD APPEND "\"")
 list(JOIN LIBOMPTARGET_PLUGINS_TO_LOAD "," ENABLED_OFFLOAD_PLUGINS)

offload/src/PluginManager.cpp

@@ -23,9 +23,6 @@ using namespace llvm::sys;
 
 PluginManager *PM = nullptr;
 
-// List of all plugins that can support offloading.
-static const char *RTLNames[] = {ENABLED_OFFLOAD_PLUGINS};
-
 Expected<std::unique_ptr<PluginAdaptorTy>>
 PluginAdaptorTy::create(const std::string &Name) {
   DP("Attempting to load library '%s'...\n", Name.c_str());
@@ -95,17 +92,19 @@ void PluginManager::init() {
 
   // Attempt to open all the plugins and, if they exist, check if the interface
   // is correct and if they are supporting any devices.
-  for (const char *Name : RTLNames) {
-    auto PluginAdaptorOrErr =
-        PluginAdaptorTy::create(std::string(Name) + ".so");
-    if (!PluginAdaptorOrErr) {
-      [[maybe_unused]] std::string InfoMsg =
-          toString(PluginAdaptorOrErr.takeError());
-      DP("%s", InfoMsg.c_str());
-    } else {
-      PluginAdaptors.push_back(std::move(*PluginAdaptorOrErr));
-    }
-  }
+#define PLUGIN_TARGET(Name)                                                    \
+  do {                                                                         \
+    auto PluginAdaptorOrErr =                                                  \
+        PluginAdaptorTy::create("libomptarget.rtl." #Name ".so");              \
+    if (!PluginAdaptorOrErr) {                                                 \
+      [[maybe_unused]] std::string InfoMsg =                                   \
+          toString(PluginAdaptorOrErr.takeError());                            \
+      DP("%s", InfoMsg.c_str());                                               \
+    } else {                                                                   \
+      PluginAdaptors.push_back(std::move(*PluginAdaptorOrErr));                \
+    }                                                                          \
+  } while (false);
+#include "Shared/Targets.def"
 
   DP("RTLs loaded!\n");
 }