[OpenMP] Allow to specify what plugins to look for

[jdoerfert]

By default we now only look for the plugins we build, but the user can overwrite that with LIBOMPTARGET_PLUGINS_TO_LOAD="cuda,amdgpu,x86_64"

[llvmbot]

@llvm/pr-subscribers-openmp

Author: Johannes Doerfert (jdoerfert)

Changes

By default we now only look for the plugins we build, but the user can overwrite that with LIBOMPTARGET_PLUGINS_TO_LOAD="plugA.so","plugB.so"

---

Full diff: https://github.com/llvm/llvm-project/pull/74538.diff

3 Files Affected:

• (modified) openmp/libomptarget/CMakeLists.txt (+4-4)
• (modified) openmp/libomptarget/src/CMakeLists.txt (+22)
• (modified) openmp/libomptarget/src/PluginManager.cpp (+4)

diff --git a/openmp/libomptarget/CMakeLists.txt b/openmp/libomptarget/CMakeLists.txt
index 972b887c7c952..115189a28ce16 100644
--- a/openmp/libomptarget/CMakeLists.txt
+++ b/openmp/libomptarget/CMakeLists.txt
@@ -110,10 +110,6 @@ set(LIBOMPTARGET_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/include)
 message(STATUS "OpenMP tools dir in libomptarget: ${LIBOMP_OMP_TOOLS_INCLUDE_DIR}")
 include_directories(${LIBOMP_OMP_TOOLS_INCLUDE_DIR})
 
-# Build target agnostic offloading library.
-set(LIBOMPTARGET_SRC_DIR ${CMAKE_CURRENT_SOURCE_DIR}/src)
-add_subdirectory(${LIBOMPTARGET_SRC_DIR})
-
 # Definitions for testing, for reuse when testing libomptarget-nvptx.
 set(LIBOMPTARGET_OPENMP_HEADER_FOLDER "${LIBOMP_INCLUDE_DIR}" CACHE STRING
   "Path to folder containing omp.h")
@@ -129,5 +125,9 @@ add_subdirectory(plugins-nextgen)
 add_subdirectory(DeviceRTL)
 add_subdirectory(tools)
 
+# Build target agnostic offloading library.
+set(LIBOMPTARGET_SRC_DIR ${CMAKE_CURRENT_SOURCE_DIR}/src)
+add_subdirectory(${LIBOMPTARGET_SRC_DIR})
+
 # Add tests.
 add_subdirectory(test)
diff --git a/openmp/libomptarget/src/CMakeLists.txt b/openmp/libomptarget/src/CMakeLists.txt
index 7c311f738ac8e..f5e0672087c38 100644
--- a/openmp/libomptarget/src/CMakeLists.txt
+++ b/openmp/libomptarget/src/CMakeLists.txt
@@ -55,6 +55,28 @@ target_compile_definitions(omptarget PRIVATE
   DEBUG_PREFIX="omptarget"
 )
 
+macro(check_plugin_target target)
+if (TARGET ${target})
+	if (NOT LIBOMPTARGET_PLUGINS_TO_LOAD)
+		set(LIBOMPTARGET_PLUGINS_TO_LOAD "\"lib${target}\"")
+	else()
+		set(LIBOMPTARGET_PLUGINS_TO_LOAD ${LIBOMPTARGET_PLUGINS_TO_LOAD},"lib${target}")
+	endif()
+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(omptarget.rtl.ppc64)
+	check_plugin_target(omptarget.rtl.x86_64)
+	check_plugin_target(omptarget.rtl.cuda)
+	check_plugin_target(omptarget.rtl.aarch64)
+	check_plugin_target(omptarget.rtl.amdgpu)
+endif()
+
+target_compile_definitions(omptarget PRIVATE ENABLED_OFFLOAD_PLUGINS=${LIBOMPTARGET_PLUGINS_TO_LOAD})
+
 # libomptarget.so needs to be aware of where the plugins live as they
 # are now separated in the build directory.
 set_target_properties(omptarget PROPERTIES
diff --git a/openmp/libomptarget/src/PluginManager.cpp b/openmp/libomptarget/src/PluginManager.cpp
index 931143ad2347d..f9f19240a17b5 100644
--- a/openmp/libomptarget/src/PluginManager.cpp
+++ b/openmp/libomptarget/src/PluginManager.cpp
@@ -23,11 +23,15 @@ PluginManager *PM;
 
 // List of all plugins that can support offloading.
 static const char *RTLNames[] = {
+#ifdef ENABLED_OFFLOAD_PLUGINS
+    ENABLED_OFFLOAD_PLUGINS
+#else
     /* PowerPC target       */ "libomptarget.rtl.ppc64",
     /* x86_64 target        */ "libomptarget.rtl.x86_64",
     /* CUDA target          */ "libomptarget.rtl.cuda",
     /* AArch64 target       */ "libomptarget.rtl.aarch64",
     /* AMDGPU target        */ "libomptarget.rtl.amdgpu",
+#endif
 };
 
 PluginAdaptorTy::PluginAdaptorTy(const std::string &Name) : Name(Name) {

[shiltian]

Can we just use arch name, such as cuda, ppc64, instead of the full name?

[jdoerfert]

Can we just use arch name, such as cuda, ppc64, instead of the full name?

Done.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[shiltian]

LG