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This reverts commit d763c6e5e2d0a6b34097aa7dabca31e9aff9b0b6. Adds the patch by @hans from https://github.com/llvm/llvm-project/issues/62719 This patch fixes the Windows build. d763c6e5e2d0a6b34097aa7dabca31e9aff9b0b6 reverted the reviews D144509 [CMake] Bumps minimum version to 3.20.0. This partly undoes D137724. This change has been discussed on discourse https://discourse.llvm.org/t/rfc-upgrading-llvms-minimum-required-cmake-version/66193 Note this does not remove work-arounds for older CMake versions, that will be done in followup patches. D150532 [OpenMP] Compile assembly files as ASM, not C Since CMake 3.20, CMake explicitly passes "-x c" (or equivalent) when compiling a file which has been set as having the language C. This behaviour change only takes place if "cmake_minimum_required" is set to 3.20 or newer, or if the policy CMP0119 is set to new. Attempting to compile assembly files with "-x c" fails, however this is workarounded in many cases, as OpenMP overrides this with "-x assembler-with-cpp", however this is only added for non-Windows targets. Thus, after increasing cmake_minimum_required to 3.20, this breaks compiling the GNU assembly for Windows targets; the GNU assembly is used for ARM and AArch64 Windows targets when building with Clang. This patch unbreaks that. D150688 [cmake] Set CMP0091 to fix Windows builds after the cmake_minimum_required bump The build uses other mechanism to select the runtime. Fixes #62719 Reviewed By: #libc, Mordante Differential Revision: https://reviews.llvm.org/D151344
=========================
LLVM OpenMP CMake Modules
=========================
This directory contains CMake modules for OpenMP. These can be included into a
project to include different OpenMP features.
.. contents::
:local:
Find OpenMP Target Support
==========================
This module will attempt to find OpenMP target offloading support for a given
device. The module will attempt to compile a test program using known compiler
flags for each requested architecture. If successful, the flags required for
offloading will be loaded into the ``OpenMPTarget::OpenMPTarget_<device>``
target or the ``OpenMPTarget_<device>_FLAGS`` variable. Currently supported target
devices are ``NVPTX`` and ``AMDGPU``. This module is still under development so
some features may be missing.
To use this module, simply add the path to CMake's current module path and call
``find_package``. The module will be installed with your OpenMP installation by
default. Including OpenMP offloading support in an application should now only
require a few additions.
.. code-block:: cmake
cmake_minimum_required(VERSION 3.20.0)
project(offloadTest VERSION 1.0 LANGUAGES CXX)
list(APPEND CMAKE_MODULE_PATH "${PATH_TO_OPENMP_INSTALL}/lib/cmake/openmp")
find_package(OpenMPTarget REQUIRED NVPTX)
add_executable(offload)
target_link_libraries(offload PRIVATE OpenMPTarget::OpenMPTarget_NVPTX)
target_sources(offload PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/src/Main.cpp)
Using this module requires at least CMake version 3.20.0. Supported languages
are C and C++ with Fortran support planned in the future. If your application
requires building for a specific device architecture you can set the
``OpenMPTarget_<device>_ARCH=<flag>`` variable. Compiler support is best for
Clang but this module should work for other compiler vendors such as IBM or GNU.