[Offload] Support standalone build for OpenMP and Offload

The standalone offload build will just search for
the ompt header and if found then OMPT support will
be enabled. This caused the LIBOMP_HAVE_VERSION_SCRIPT_FLAG
detection and pythonize_bool to move into offload/CMakeLists.txt.

If the cmake compiler is clang, get the resource directory for
installation of openmp headers. find_package(LLVM) is already
called in LibomptargetGetDependencies.

Depends on #75125

Author: saiislam

offload/CMakeLists.txt

@@ -10,6 +10,13 @@
 #
 ##===----------------------------------------------------------------------===##
 
+cmake_minimum_required(VERSION 3.20.0)
+
+if ("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
+  set(OPENMP_STANDALONE_BUILD TRUE)
+  project(offload C CXX ASM)
+endif()
+
 set(ENABLE_LIBOMPTARGET ON)
 # Currently libomptarget cannot be compiled on Windows or MacOS X.
 # Since the device plugins are only supported on Linux anyway,
@@ -35,11 +42,12 @@ endif()
 # TODO: Leftover from the move, could probably be just LLVM_LIBDIR_SUFFIX everywhere.
 set(OFFLOAD_INSTALL_LIBDIR "lib${LLVM_LIBDIR_SUFFIX}")
 
-set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
+set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
 
 # Add path for custom modules
 list(INSERT CMAKE_MODULE_PATH 0
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
+  "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
   "${LLVM_COMMON_CMAKE_UTILS}/Modules"
   )
 
@@ -190,6 +198,58 @@ if (LIBOMPTARGET_USE_LTO)
   list(APPEND offload_link_flags ${CMAKE_CXX_COMPILE_OPTIONS_IPO})
 endif()
 
+if(OPENMP_STANDALONE_BUILD)
+  if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    execute_process(
+      OUTPUT_STRIP_TRAILING_WHITESPACE
+      COMMAND ${CMAKE_CXX_COMPILER} --print-resource-dir
+      RESULT_VARIABLE COMMAND_RETURN_CODE
+      OUTPUT_VARIABLE COMPILER_RESOURCE_DIR
+    )
+  endif()
+
+  set(LIBOMP_HAVE_OMPT_SUPPORT FALSE)
+  set(LIBOMP_OMPT_SUPPORT FALSE)
+
+  find_path (
+    LIBOMP_OMP_TOOLS_INCLUDE_DIR
+    NAMES
+      omp-tools.h
+    HINTS
+    ${COMPILER_RESOURCE_DIR}/include
+    ${CMAKE_INSTALL_PREFIX}/include
+  )
+
+  if(LIBOMP_OMP_TOOLS_INCLUDE_DIR)
+    set(LIBOMP_HAVE_OMPT_SUPPORT TRUE)
+    set(LIBOMP_OMPT_SUPPORT TRUE)
+  endif()
+
+  # LLVM_LIBRARY_DIRS set by find_package(LLVM) in LibomptargetGetDependencies
+  find_library (
+    LIBOMP_STANDALONE
+    NAMES
+      omp
+    HINTS
+      ${CMAKE_INSTALL_PREFIX}/lib
+      ${LLVM_LIBRARY_DIRS}
+    REQUIRED
+  )
+# Check LIBOMP_HAVE_VERSION_SCRIPT_FLAG
+  include(LLVMCheckCompilerLinkerFlag)
+  if(NOT APPLE)
+    llvm_check_compiler_linker_flag(C "-Wl,--version-script=${CMAKE_CURRENT_LIST_DIR}/../openmp/runtime/src/exports_test_so.txt" LIBOMP_HAVE_VERSION_SCRIPT_FLAG)
+  endif()
+
+  macro(pythonize_bool var)
+  if (${var})
+    set(${var} True)
+  else()
+    set(${var} False)
+  endif()
+  endmacro()
+endif()
+
 # OMPT support for libomptarget
 # Follow host OMPT support and check if host support has been requested.
 # LIBOMP_HAVE_OMPT_SUPPORT indicates whether host OMPT support has been implemented.
@@ -216,7 +276,9 @@ pythonize_bool(LIBOMPTARGET_GPU_LIBC_SUPPORT)
 
 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})
+if(LIBOMP_OMP_TOOLS_INCLUDE_DIR)
+  include_directories(${LIBOMP_OMP_TOOLS_INCLUDE_DIR})
+endif()
 
 set(LIBOMPTARGET_LLVM_LIBRARY_DIR "${LLVM_LIBRARY_DIR}" CACHE STRING
   "Path to folder containing llvm library libomptarget.so")

offload/plugins-nextgen/host/CMakeLists.txt

@@ -33,7 +33,7 @@ endif()
 
 # Install plugin under the lib destination folder.
 install(TARGETS omptarget.rtl.${machine}
-        LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
+        LIBRARY DESTINATION "${OFFLOAD_INSTALL_LIBDIR}")
 set_target_properties(omptarget.rtl.${machine} PROPERTIES
   INSTALL_RPATH "$ORIGIN" BUILD_RPATH "$ORIGIN:${CMAKE_CURRENT_BINARY_DIR}/.."
   POSITION_INDEPENDENT_CODE ON

offload/src/CMakeLists.txt

@@ -12,6 +12,12 @@
 
 libomptarget_say("Building offloading runtime library libomptarget.")
 
+if(LIBOMP_STANDALONE)
+  set(LIBOMP ${LIBOMP_STANDALONE})
+else()
+  set(LIBOMP omp)
+endif()
+
 add_llvm_library(omptarget
   SHARED
 
@@ -38,7 +44,7 @@ add_llvm_library(omptarget
 
   LINK_LIBS
   PUBLIC
-  omp
+  ${LIBOMP}
 
   NO_INSTALL_RPATH
   BUILDTREE_ONLY

openmp/CMakeLists.txt

@@ -113,7 +113,17 @@ option(OPENMP_ENABLE_LIBOMP_PROFILING "Enable time profiling for libomp." OFF)
 
 # Header install location
 if(${OPENMP_STANDALONE_BUILD})
-  set(LIBOMP_HEADERS_INSTALL_PATH "${CMAKE_INSTALL_INCLUDEDIR}")
+  if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    execute_process(
+      OUTPUT_STRIP_TRAILING_WHITESPACE
+      COMMAND ${CMAKE_CXX_COMPILER} --print-resource-dir
+      RESULT_VARIABLE COMMAND_RETURN_CODE
+      OUTPUT_VARIABLE COMPILER_RESOURCE_DIR
+    )
+    set(LIBOMP_HEADERS_INSTALL_PATH "${COMPILER_RESOURCE_DIR}/include")
+  else()
+    set(LIBOMP_HEADERS_INSTALL_PATH "${CMAKE_INSTALL_INCLUDEDIR}")
+  endif()
 else()
   include(GetClangResourceDir)
   get_clang_resource_dir(LIBOMP_HEADERS_INSTALL_PATH SUBDIR include)