# See for https://openmp.llvm.org/SupportAndFAQ.html for instructions on how
# to build offload with CMake.

cmake_minimum_required(VERSION 3.20.0)
set(LLVM_SUBPROJECT_TITLE "liboffload")

# Check that the library can actually be built.
if(APPLE OR WIN32 OR WASM)
  message(WARNING "libomptarget cannot be built on Windows and MacOS X!")
  return()
elseif("${LLVM_DEFAULT_TARGET_TRIPLE}" MATCHES "^(amdgcn|nvptx|spirv)" OR
       "${CMAKE_CXX_COMPILER_TARGET}" MATCHES "^(amdgcn|nvptx|spirv)")
  message(WARNING "offload cannot be built on GPU targets yet.")
  return()
elseif(NOT "cxx_std_17" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
  message(WARNING "Host compiler must support C++17 to build libomptarget!")
  return()
elseif(NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
  message(WARNING "libomptarget on 32-bit systems is not supported!")
  return()
endif()

set(OFFLOAD_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})

# When building in tree we install the runtime according to the LLVM settings.
# TODO: Use common runtimes infrastructure for output and install paths
if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
  set(OFFLOAD_TARGET_SUBDIR "${LLVM_DEFAULT_TARGET_TRIPLE}")
  if(OFFLOAD_LIBDIR_SUBDIR)
    string(APPEND OFFLOAD_TARGET_SUBDIR "/${OFFLOAD_LIBDIR_SUBDIR}")
  endif()
  cmake_path(NORMAL_PATH OFFLOAD_TARGET_SUBDIR)
  set(OFFLOAD_INSTALL_LIBDIR "lib${LLVM_LIBDIR_SUFFIX}/${OFFLOAD_TARGET_SUBDIR}" CACHE STRING
    "Path where built offload libraries should be installed.")
else()
  set(OFFLOAD_INSTALL_LIBDIR "lib${LLVM_LIBDIR_SUFFIX}" CACHE STRING
    "Path where built offload libraries should be installed.")
endif()

set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)

option(OFFLOAD_INCLUDE_TESTS "Generate and build offload tests." ${LLVM_INCLUDE_TESTS})

# Add path for custom modules
list(INSERT CMAKE_MODULE_PATH 0
  "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
  "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
  "${CMAKE_CURRENT_SOURCE_DIR}/../runtimes/cmake/Modules"
  "${LLVM_COMMON_CMAKE_UTILS}"
  "${LLVM_COMMON_CMAKE_UTILS}/Modules"
  )

set(OPENMP_TEST_C_COMPILER_default "${LLVM_TOOLS_BINARY_DIR}/clang${CMAKE_EXECUTABLE_SUFFIX}")
set(OPENMP_TEST_CXX_COMPILER_default "${LLVM_TOOLS_BINARY_DIR}/clang++${CMAKE_EXECUTABLE_SUFFIX}")
set(OPENMP_TEST_Fortran_COMPILER_default "${LLVM_TOOLS_BINARY_DIR}/flang${CMAKE_EXECUTABLE_SUFFIX}")
if (NOT TARGET "clang")
  set(OPENMP_TEST_C_COMPILER_default "${CMAKE_C_COMPILER}")
  set(OPENMP_TEST_CXX_COMPILER_default "${CMAKE_CXX_COMPILER}")
endif()
if (NOT TARGET "flang")
  if (CMAKE_Fortran_COMPILER)
    set(OPENMP_TEST_Fortran_COMPILER_default "${CMAKE_Fortran_COMPILER}")
  else()
    unset(OPENMP_TEST_Fortran_COMPILER_default)
  endif()
endif()

set(OPENMP_TEST_C_COMPILER "${OPENMP_TEST_C_COMPILER_default}" CACHE STRING
  "C compiler to use for testing OpenMP runtime libraries.")
set(OPENMP_TEST_CXX_COMPILER "${OPENMP_TEST_CXX_COMPILER_default}" CACHE STRING
  "C++ compiler to use for testing OpenMP runtime libraries.")
set(OPENMP_TEST_Fortran_COMPILER "${OPENMP_TEST_Fortran_COMPILER_default}" CACHE STRING
  "Fortran compiler to use for testing OpenMP runtime libraries.")

# Set fortran test compiler if flang is found
if (EXISTS "${OPENMP_TEST_Fortran_COMPILER}")
  message("Using local flang build at ${OPENMP_TEST_Fortran_COMPILER}")
else()
  unset(OPENMP_TEST_Fortran_COMPILER)
endif()

# If not standalone, set CMAKE_CXX_STANDARD but don't set the global cache value,
# only set it locally for OpenMP.
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED NO)
set(CMAKE_CXX_EXTENSIONS NO)

# Set the path of all resulting libraries to a unified location so that it can
# be used for testing.
# TODO: Use common runtimes infrastructure for output and install paths
set(LIBOMPTARGET_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBOMPTARGET_LIBRARY_DIR})
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBOMPTARGET_LIBRARY_DIR})
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LIBOMPTARGET_LIBRARY_DIR})

if(NOT LLVM_LIBRARY_OUTPUT_INTDIR)
  set(LIBOMPTARGET_INTDIR ${LIBOMPTARGET_LIBRARY_DIR})
else()
  set(LIBOMPTARGET_INTDIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
endif()

# Get dependencies for the different components of the project.
include(LibomptargetGetDependencies)

# Set up testing infrastructure.
include(OpenMPTesting)

include(CheckCXXCompilerFlag)
check_cxx_compiler_flag(-Werror=global-constructors OFFLOAD_HAVE_WERROR_CTOR)

# LLVM source tree is required at build time for libomptarget
if (NOT LIBOMPTARGET_LLVM_INCLUDE_DIRS)
  message(FATAL_ERROR "Missing definition for LIBOMPTARGET_LLVM_INCLUDE_DIRS")
endif()

if(DEFINED LIBOMPTARGET_BUILD_CUDA_PLUGIN OR
   DEFINED LIBOMPTARGET_BUILD_AMDGPU_PLUGIN)
  message(WARNING "Option removed, use 'LIBOMPTARGET_PLUGINS_TO_BUILD' instead")
endif()

set(LIBOMPTARGET_ALL_PLUGIN_TARGETS amdgpu cuda)
set(LIBOMPTARGET_PLUGINS_TO_BUILD "all" CACHE STRING
    "Semicolon-separated list of plugins to use: cuda, amdgpu, level_zero, or \"all\".")

if(LIBOMPTARGET_PLUGINS_TO_BUILD STREQUAL "all")
  set(LIBOMPTARGET_PLUGINS_TO_BUILD ${LIBOMPTARGET_ALL_PLUGIN_TARGETS})
endif()

list(APPEND LIBOMPTARGET_PLUGINS_TO_BUILD "host")
list(REMOVE_DUPLICATES LIBOMPTARGET_PLUGINS_TO_BUILD)

if(NOT (CMAKE_SYSTEM_PROCESSOR MATCHES "(x86_64)|(ppc64le)|(aarch64)$"
        AND CMAKE_SYSTEM_NAME MATCHES "Linux"))
  if("amdgpu" IN_LIST LIBOMPTARGET_PLUGINS_TO_BUILD)
    message(STATUS "Not building AMDGPU plugin: only support AMDGPU in "
                   "Linux x86_64, ppc64le, or aarch64 hosts")
    list(REMOVE_ITEM LIBOMPTARGET_PLUGINS_TO_BUILD "amdgpu")
  endif()
  if("cuda" IN_LIST LIBOMPTARGET_PLUGINS_TO_BUILD)
    message(STATUS "Not building CUDA plugin: only support CUDA in "
                   "Linux x86_64, ppc64le, or aarch64 hosts")
    list(REMOVE_ITEM LIBOMPTARGET_PLUGINS_TO_BUILD "cuda")
  endif()
endif()
if(NOT (CMAKE_SYSTEM_PROCESSOR MATCHES "(x86_64)|(AMD64)$" AND
        CMAKE_SYSTEM_NAME MATCHES "Linux|Windows"))
  if("level_zero" IN_LIST LIBOMPTARGET_PLUGINS_TO_BUILD)
    message(STATUS "Not building Level Zero plugin: it is only supported on "
                   "Linux/Windows x86_64 or ppc64le hosts")
    list(REMOVE_ITEM LIBOMPTARGET_PLUGINS_TO_BUILD "level_zero")
  endif()
endif()
if("level_zero" IN_LIST LIBOMPTARGET_PLUGINS_TO_BUILD AND
   NOT LIBOMPTARGET_DEP_LEVEL_ZERO_FOUND)
  list(REMOVE_ITEM LIBOMPTARGET_PLUGINS_TO_BUILD "level_zero")
endif()
message(STATUS "Building the offload library with support for "
               "the \"${LIBOMPTARGET_PLUGINS_TO_BUILD}\" plugins")

set(LIBOMPTARGET_DLOPEN_PLUGINS "${LIBOMPTARGET_PLUGINS_TO_BUILD}" CACHE STRING
    "Semicolon-separated list of plugins to use 'dlopen' for runtime linking")

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.
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} aarch64-unknown-linux-gnu")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} aarch64-unknown-linux-gnu-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} amdgcn-amd-amdhsa")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} powerpc64le-ibm-linux-gnu")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} powerpc64le-ibm-linux-gnu-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} powerpc64-ibm-linux-gnu")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} powerpc64-ibm-linux-gnu-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} x86_64-unknown-linux-gnu")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} x86_64-unknown-linux-gnu-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} nvptx64-nvidia-cuda")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} nvptx64-nvidia-cuda-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} nvptx64-nvidia-cuda-JIT-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} s390x-ibm-linux-gnu")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} s390x-ibm-linux-gnu-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} riscv64-unknown-linux-gnu")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} riscv64-unknown-linux-gnu-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} loongarch64-unknown-linux-gnu")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} loongarch64-unknown-linux-gnu-LTO")
set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} spirv64-intel")

# Once the plugins for the different targets are validated, they will be added to
# the list of supported targets in the current system.
set (LIBOMPTARGET_SYSTEM_TARGETS "")
set (LIBOMPTARGET_TESTED_PLUGINS "")

# Check whether using debug mode. In debug mode, allow dumping progress
# messages at runtime by default. Otherwise, it can be enabled
# independently using the LIBOMPTARGET_ENABLE_DEBUG option.
string( TOLOWER "${CMAKE_BUILD_TYPE}" LIBOMPTARGET_CMAKE_BUILD_TYPE)
if(LIBOMPTARGET_CMAKE_BUILD_TYPE MATCHES debug)
  option(LIBOMPTARGET_ENABLE_DEBUG "Allow debug output with the environment variable LIBOMPTARGET_DEBUG=1" ON)
else()
  option(LIBOMPTARGET_ENABLE_DEBUG "Allow debug output with the environment variable LIBOMPTARGET_DEBUG=1" OFF)
endif()
if(LIBOMPTARGET_ENABLE_DEBUG)
  add_definitions(-DOMPTARGET_DEBUG)
endif()

# No exceptions and no RTTI, except if requested.
set(offload_compile_flags -fno-exceptions)
if(NOT LLVM_ENABLE_RTTI)
  set(offload_compile_flags ${offload_compile_flags} -fno-rtti)
endif()
if(OFFLOAD_HAVE_WERROR_CTOR)
  list(APPEND offload_compile_flags -Werror=global-constructors)
endif()

# TODO: Consider enabling LTO by default if supported.
# https://cmake.org/cmake/help/latest/module/CheckIPOSupported.html can be used
# to test for working LTO. However, before CMake 3.24 this will test the
# default linker and ignore options such as LLVM_ENABLE_LLD. As a result, CMake
# would test whether LTO works with the default linker but build with another one.
# In a typical scenario, libomptarget is compiled with the in-tree Clang, but
# linked with ld.gold, which requires the LLVMgold plugin, when it actually
# would work with the lld linker (or also fail because the system lld is too old
# to understand opaque pointers). Using gcc as the compiler would pass the test, but fail
# when linking with lld since does not understand gcc's LTO format.
set(LIBOMPTARGET_USE_LTO FALSE CACHE BOOL "Use LTO for the offload runtimes if available")
if (LIBOMPTARGET_USE_LTO)
  # CMake sets CMAKE_CXX_COMPILE_OPTIONS_IPO depending on the compiler and is
  # also what CheckIPOSupported uses to test support.
  list(APPEND offload_compile_flags ${CMAKE_CXX_COMPILE_OPTIONS_IPO})
  list(APPEND offload_link_flags ${CMAKE_CXX_COMPILE_OPTIONS_IPO})
endif()

macro(pythonize_bool var)
if (${var})
  set(${var} True)
else()
  set(${var} False)
endif()
endmacro()

# 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.
# LIBOMP_OMPT_SUPPORT indicates whether host OMPT support has been requested (default is ON).
# LIBOMPTARGET_OMPT_SUPPORT indicates whether target OMPT support has been requested (default is ON).
set(OMPT_TARGET_DEFAULT FALSE)
if ((LIBOMP_HAVE_OMPT_SUPPORT) AND (LIBOMP_OMPT_SUPPORT) AND (NOT WIN32))
  set (OMPT_TARGET_DEFAULT TRUE)
endif()
set(LIBOMPTARGET_OMPT_SUPPORT ${OMPT_TARGET_DEFAULT} CACHE BOOL "OMPT-target-support?")
if ((OMPT_TARGET_DEFAULT) AND (LIBOMPTARGET_OMPT_SUPPORT))
  add_definitions(-DOMPT_SUPPORT=1)
  message(STATUS "OMPT target enabled")
else()
  set(LIBOMPTARGET_OMPT_SUPPORT FALSE)
  message(STATUS "OMPT target disabled")
endif()

pythonize_bool(LIBOMPTARGET_OMPT_SUPPORT)

if(${LLVM_LIBC_GPU_BUILD})
  set(LIBOMPTARGET_HAS_LIBC TRUE)
else()
  set(LIBOMPTARGET_HAS_LIBC FALSE)
endif()
set(LIBOMPTARGET_GPU_LIBC_SUPPORT ${LIBOMPTARGET_HAS_LIBC} CACHE BOOL
    "Libomptarget support for the GPU libc")
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})
endif()

# TODO: Use RUNTIMES_OUTPUT_RESOURCE_LIB_DIR instead
set(LIBOMPTARGET_LLVM_LIBRARY_DIR "${LLVM_LIBRARY_DIR}" CACHE STRING
  "Path to folder containing llvm library libomptarget.so")
set(LIBOMPTARGET_LLVM_LIBRARY_INTDIR "${LIBOMPTARGET_INTDIR}" CACHE STRING
  "Path to folder where intermediate libraries will be output")

add_subdirectory(tools/offload-tblgen)

# Build offloading plugins and device RTLs if they are available.
add_subdirectory(plugins-nextgen)
add_subdirectory(tools)
add_subdirectory(docs)

# Build target agnostic offloading library.
add_subdirectory(libomptarget)

add_subdirectory(liboffload)

# Add tests.
if(OFFLOAD_INCLUDE_TESTS)
  add_subdirectory(test)
  add_subdirectory(unittests)
endif()

# Expose a high-level target to build the offloading runtimes.
# This is used in pre-commit CI to run a build of the libraries without requiring
# to invoke the check-* targets.
add_custom_target(offload
  COMMENT "Building offloading runtime libraries and plugins"
)
if(TARGET omptarget)
  add_dependencies(offload omptarget)
endif()
if(TARGET LLVMOffload)
  add_dependencies(offload LLVMOffload)
endif()