forked from OSchip/llvm-project
337 lines
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ReStructuredText
337 lines
12 KiB
ReStructuredText
========================================
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How to Build the LLVM* OpenMP* Libraries
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========================================
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This repository requires `CMake <http://www.cmake.org/>`_ v2.8.0 or later. LLVM
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and Clang need a more recent version which also applies for in-tree builds. For
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more information than available in this document please see
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`LLVM's CMake documentation <https://llvm.org/docs/CMake.html>`_ and the
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`official documentation <https://cmake.org/cmake/help/v2.8.0/cmake.html>`_.
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.. contents::
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:local:
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How to Call CMake Initially, then Repeatedly
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============================================
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- When calling CMake for the first time, all needed compiler options must be
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specified on the command line. After this initial call to CMake, the compiler
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definitions must not be included for further calls to CMake. Other options
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can be specified on the command line multiple times including all definitions
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in the build options section below.
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- Example of configuring, building, reconfiguring, rebuilding:
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.. code-block:: console
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$ mkdir build
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$ cd build
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$ cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ .. # Initial configuration
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$ make
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...
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$ make clean
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$ cmake -DCMAKE_BUILD_TYPE=Debug .. # Second configuration
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$ make
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...
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$ rm -rf *
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$ cmake -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ .. # Third configuration
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$ make
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- Notice in the example how the compiler definitions are only specified for an
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empty build directory, but other build options are used at any time.
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- The file ``CMakeCache.txt`` which is created after the first call to CMake is
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a configuration file which holds all values for the build options. These
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values can be changed using a text editor to modify ``CMakeCache.txt`` as
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opposed to using definitions on the command line.
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- To have CMake create a particular type of build generator file simply include
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the ``-G <Generator name>`` option:
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.. code-block:: console
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$ cmake -G "Unix Makefiles" ...
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You can see a list of generators CMake supports by executing the cmake command
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with no arguments.
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Instructions to Build
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=====================
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.. code-block:: console
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$ cd openmp_top_level/ [ this directory with libomptarget/, runtime/, etc. ]
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$ mkdir build
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$ cd build
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[ Unix* Libraries ]
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$ cmake -DCMAKE_C_COMPILER=<C Compiler> -DCMAKE_CXX_COMPILER=<C++ Compiler> ..
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[ Windows* Libraries ]
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$ cmake -G <Generator Type> -DCMAKE_C_COMPILER=<C Compiler> -DCMAKE_CXX_COMPILER=<C++ Compiler> -DCMAKE_ASM_MASM_COMPILER=[ml | ml64] -DCMAKE_BUILD_TYPE=Release ..
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$ make
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$ make install
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CMake Options
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=============
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Builds with CMake can be customized by means of options as already seen above.
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One possibility is to pass them via the command line:
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.. code-block:: console
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$ cmake -DOPTION=<value> path/to/source
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.. note:: The first value listed is the respective default for that option.
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Generic Options
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---------------
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For full documentation consult the CMake manual or execute
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``cmake --help-variable VARIABLE_NAME`` to get information about a specific
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variable.
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**CMAKE_BUILD_TYPE** = ``Release|Debug|RelWithDebInfo``
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Build type can be ``Release``, ``Debug``, or ``RelWithDebInfo`` which chooses
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the optimization level and presence of debugging symbols.
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**CMAKE_C_COMPILER** = <C compiler name>
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Specify the C compiler.
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**CMAKE_CXX_COMPILER** = <C++ compiler name>
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Specify the C++ compiler.
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**CMAKE_Fortran_COMPILER** = <Fortran compiler name>
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Specify the Fortran compiler. This option is only needed when
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**LIBOMP_FORTRAN_MODULES** is ``ON`` (see below). So typically, a Fortran
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compiler is not needed during the build.
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**CMAKE_ASM_MASM_COMPILER** = ``ml|ml64``
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This option is only relevant for Windows*.
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Options for all Libraries
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-------------------------
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**OPENMP_ENABLE_WERROR** = ``OFF|ON``
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Treat warnings as errors and fail, if a compiler warning is triggered.
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**OPENMP_LIBDIR_SUFFIX** = ``""``
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Extra suffix to append to the directory where libraries are to be installed.
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**OPENMP_TEST_C_COMPILER** = ``${CMAKE_C_COMPILER}``
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Compiler to use for testing. Defaults to the compiler that was also used for
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building.
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**OPENMP_TEST_CXX_COMPILER** = ``${CMAKE_CXX_COMPILER}``
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Compiler to use for testing. Defaults to the compiler that was also used for
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building.
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**OPENMP_LLVM_TOOLS_DIR** = ``/path/to/built/llvm/tools``
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Additional path to search for LLVM tools needed by tests.
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**OPENMP_LLVM_LIT_EXECUTABLE** = ``/path/to/llvm-lit``
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Specify full path to ``llvm-lit`` executable for running tests. The default
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is to search the ``PATH`` and the directory in **OPENMP_LLVM_TOOLS_DIR**.
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**OPENMP_FILECHECK_EXECUTABLE** = ``/path/to/FileCheck``
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Specify full path to ``FileCheck`` executable for running tests. The default
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is to search the ``PATH`` and the directory in **OPENMP_LLVM_TOOLS_DIR**.
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Options for ``libomp``
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----------------------
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**LIBOMP_ARCH** = ``aarch64|arm|i386|mic|mips|mips64|ppc64|ppc64le|x86_64|riscv64``
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The default value for this option is chosen based on probing the compiler for
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architecture macros (e.g., is ``__x86_64__`` predefined by compiler?).
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**LIBOMP_MIC_ARCH** = ``knc|knf``
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Intel(R) Many Integrated Core Architecture (Intel(R) MIC Architecture) to
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build for. This value is ignored if **LIBOMP_ARCH** does not equal ``mic``.
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**LIBOMP_LIB_TYPE** = ``normal|profile|stubs``
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Library type can be ``normal``, ``profile``, or ``stubs``.
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**LIBOMP_USE_VERSION_SYMBOLS** = ``ON|OFF``
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Use versioned symbols for building the library. This option only makes sense
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for ELF based libraries where version symbols are supported (Linux*, some BSD*
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variants). It is ``OFF`` by default for Windows* and macOS*, but ``ON`` for
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other Unix based operating systems.
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**LIBOMP_ENABLE_SHARED** = ``ON|OFF``
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Build a shared library. If this option is ``OFF``, static OpenMP libraries
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will be built instead of dynamic ones.
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.. note::
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Static libraries are not supported on Windows*.
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**LIBOMP_FORTRAN_MODULES** = ``OFF|ON``
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Create the Fortran modules (requires Fortran compiler).
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macOS* Fat Libraries
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""""""""""""""""""""
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On macOS* machines, it is possible to build universal (or fat) libraries which
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include both i386 and x86_64 architecture objects in a single archive.
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.. code-block:: console
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$ cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_OSX_ARCHITECTURES='i386;x86_64' ..
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$ make
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There is also an option **LIBOMP_OSX_ARCHITECTURES** which can be set in case
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this is an LLVM source tree build. It will only apply for the ``libomp`` library
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avoids having the entire LLVM/Clang build produce universal binaries.
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Optional Features
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"""""""""""""""""
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**LIBOMP_USE_ADAPTIVE_LOCKS** = ``ON|OFF``
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Include adaptive locks, based on Intel(R) Transactional Synchronization
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Extensions (Intel(R) TSX). This feature is x86 specific and turned ``ON``
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by default for IA-32 architecture and Intel(R) 64 architecture.
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**LIBOMP_USE_INTERNODE_ALIGNMENT** = ``OFF|ON``
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Align certain data structures on 4096-byte. This option is useful on
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multi-node systems where a small ``CACHE_LINE`` setting leads to false sharing.
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**LIBOMP_OMPT_SUPPORT** = ``ON|OFF``
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Include support for the OpenMP Tools Interface (OMPT).
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This option is supported and ``ON`` by default for x86, x86_64, AArch64,
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PPC64 and RISCV64 on Linux* and macOS*.
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This option is ``OFF`` if this feature is not supported for the platform.
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**LIBOMP_OMPT_OPTIONAL** = ``ON|OFF``
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Include support for optional OMPT functionality. This option is ignored if
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**LIBOMP_OMPT_SUPPORT** is ``OFF``.
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**LIBOMP_STATS** = ``OFF|ON``
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Include stats-gathering code.
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**LIBOMP_USE_DEBUGGER** = ``OFF|ON``
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Include the friendly debugger interface.
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**LIBOMP_USE_HWLOC** = ``OFF|ON``
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Use `OpenMPI's hwloc library <https://www.open-mpi.org/projects/hwloc/>`_ for
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topology detection and affinity.
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**LIBOMP_HWLOC_INSTALL_DIR** = ``/path/to/hwloc/install/dir``
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Specify install location of hwloc. The configuration system will look for
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``hwloc.h`` in ``${LIBOMP_HWLOC_INSTALL_DIR}/include`` and the library in
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``${LIBOMP_HWLOC_INSTALL_DIR}/lib``. The default is ``/usr/local``.
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This option is only used if **LIBOMP_USE_HWLOC** is ``ON``.
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Additional Compiler Flags
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"""""""""""""""""""""""""
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These flags are **appended**, they do not overwrite any of the preset flags.
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**LIBOMP_CPPFLAGS** = <space-separated flags>
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Additional C preprocessor flags.
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**LIBOMP_CXXFLAGS** = <space-separated flags>
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Additional C++ compiler flags.
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**LIBOMP_ASMFLAGS** = <space-separated flags>
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Additional assembler flags.
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**LIBOMP_LDFLAGS** = <space-separated flags>
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Additional linker flags.
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**LIBOMP_LIBFLAGS** = <space-separated flags>
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Additional libraries to link.
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**LIBOMP_FFLAGS** = <space-separated flags>
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Additional Fortran compiler flags.
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Options for ``libomptarget``
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----------------------------
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**LIBOMPTARGET_OPENMP_HEADER_FOLDER** = ``""``
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Path of the folder that contains ``omp.h``. This is required for testing
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out-of-tree builds.
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**LIBOMPTARGET_OPENMP_HOST_RTL_FOLDER** = ``""``
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Path of the folder that contains ``libomp.so``. This is required for testing
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out-of-tree builds.
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Options for ``NVPTX device RTL``
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--------------------------------
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**LIBOMPTARGET_NVPTX_ENABLE_BCLIB** = ``ON|OFF``
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Enable CUDA LLVM bitcode offloading device RTL. This is used for link time
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optimization of the OMP runtime and application code. This option is enabled
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by default if the build system determines that `CMAKE_C_COMPILER` is able to
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compile and link the library.
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**LIBOMPTARGET_NVPTX_CUDA_COMPILER** = ``""``
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Location of a CUDA compiler capable of emitting LLVM bitcode. Currently only
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the Clang compiler is supported. This is only used when building the CUDA LLVM
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bitcode offloading device RTL. If unspecified and the CMake C compiler is
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Clang, then Clang is used.
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**LIBOMPTARGET_NVPTX_BC_LINKER** = ``""``
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Location of a linker capable of linking LLVM bitcode objects. This is only
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used when building the CUDA LLVM bitcode offloading device RTL. If unspecified
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and the CMake C compiler is Clang and there exists a llvm-link binary in the
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directory containing Clang, then this llvm-link binary is used.
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**LIBOMPTARGET_NVPTX_ALTERNATE_HOST_COMPILER** = ``""``
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Host compiler to use with NVCC. This compiler is not going to be used to
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produce any binary. Instead, this is used to overcome the input compiler
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checks done by NVCC. E.g. if using a default host compiler that is not
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compatible with NVCC, this option can be use to pass to NVCC a valid compiler
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to avoid the error.
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**LIBOMPTARGET_NVPTX_COMPUTE_CAPABILITIES** = ``35``
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List of CUDA compute capabilities that should be supported by the NVPTX
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device RTL. E.g. for compute capabilities 6.0 and 7.0, the option "60,70"
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should be used. Compute capability 3.5 is the minimum required.
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**LIBOMPTARGET_NVPTX_DEBUG** = ``OFF|ON``
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Enable printing of debug messages from the NVPTX device RTL.
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Example Usages of CMake
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=======================
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Typical Invocations
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-------------------
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.. code-block:: console
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$ cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ..
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$ cmake -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ ..
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$ cmake -DCMAKE_C_COMPILER=icc -DCMAKE_CXX_COMPILER=icpc ..
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Advanced Builds with Various Options
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------------------------------------
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- Build the i386 Linux* library using GCC*
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.. code-block:: console
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$ cmake -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ -DLIBOMP_ARCH=i386 ..
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- Build the x86_64 debug Mac library using Clang*
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.. code-block:: console
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$ cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DLIBOMP_ARCH=x86_64 -DCMAKE_BUILD_TYPE=Debug ..
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- Build the library (architecture determined by probing compiler) using the
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Intel(R) C Compiler and the Intel(R) C++ Compiler. Also, create Fortran
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modules with the Intel(R) Fortran Compiler.
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.. code-block:: console
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$ cmake -DCMAKE_C_COMPILER=icc -DCMAKE_CXX_COMPILER=icpc -DCMAKE_Fortran_COMPILER=ifort -DLIBOMP_FORTRAN_MODULES=on ..
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- Have CMake find the C/C++ compiler and specify additional flags for the
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preprocessor and C++ compiler.
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.. code-blocks:: console
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$ cmake -DLIBOMP_CPPFLAGS='-DNEW_FEATURE=1 -DOLD_FEATURE=0' -DLIBOMP_CXXFLAGS='--one-specific-flag --two-specific-flag' ..
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- Build the stubs library
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.. code-blocks:: console
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$ cmake -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ -DLIBOMP_LIB_TYPE=stubs ..
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**Footnotes**
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.. [*] Other names and brands may be claimed as the property of others.
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