compiler.py

from functools import partial
from hashlib import sha1
from os import environ, path
from distutils import version
from subprocess import DEVNULL, CalledProcessError, check_output, check_call
import platform
import warnings
import sys

import numpy.ctypeslib as npct
from codepy.jit import compile_from_string
from codepy.toolchain import GCCToolchain

from devito.archinfo import NVIDIAX, SKX, POWER8, POWER9
from devito.exceptions import CompilationError
from devito.logger import debug, warning, error
from devito.parameters import configuration
from devito.tools import (as_tuple, change_directory, filter_ordered,
                          memoized_meth, make_tempdir)

__all__ = ['GNUCompiler']


def sniff_compiler_version(cc):
    """
    Detect the compiler version.

    Adapted from: ::

        https://github.com/OP2/PyOP2/
    """
    try:
        ver = check_output([cc, "--version"]).decode("utf-8")
    except (CalledProcessError, UnicodeDecodeError):
        return version.LooseVersion("unknown")
    except FileNotFoundError:
        error("The `%s` compiler isn't available on this system" % cc)
        sys.exit(1)

    if ver.startswith("gcc"):
        compiler = "gcc"
    elif ver.startswith("clang"):
        compiler = "clang"
    elif ver.startswith("Apple LLVM"):
        compiler = "clang"
    elif ver.startswith("icc"):
        compiler = "icc"
    else:
        compiler = "unknown"

    ver = version.LooseVersion("unknown")
    if compiler in ["gcc", "icc"]:
        try:
            # gcc-7 series only spits out patch level on dumpfullversion.
            ver = check_output([cc, "-dumpfullversion"], stderr=DEVNULL).decode("utf-8")
            ver = '.'.join(ver.strip().split('.')[:3])
            ver = version.StrictVersion(ver)
        except CalledProcessError:
            try:
                ver = check_output([cc, "-dumpversion"], stderr=DEVNULL).decode("utf-8")
                ver = '.'.join(ver.strip().split('.')[:3])
                ver = version.StrictVersion(ver)
            except (CalledProcessError, UnicodeDecodeError):
                pass
        except UnicodeDecodeError:
            pass

    # Pure integer versions (e.g., ggc5, rather than gcc5.0) need special handling
    try:
        ver = version.StrictVersion(float(ver))
    except TypeError:
        pass

    return ver


def sniff_mpi_distro(mpiexec):
    """
    Detect the MPI version.
    """
    try:
        ver = check_output([mpiexec, "--version"]).decode("utf-8")
        if "open-mpi" in ver:
            return 'OpenMPI'
        elif "HYDRA" in ver:
            return 'MPICH'
    except (CalledProcessError, UnicodeDecodeError):
        pass
    return 'unknown'


class Compiler(GCCToolchain):
    """
    Base class for all compiler classes.

    The base class defaults all compiler specific settings to empty lists.
    Preset configurations can be built by inheriting from `Compiler` and setting
    specific flags to the desired values, e.g.:

    .. code-block:: python
      def class MyCompiler(Compiler):
          def __init__(self):
              self.cc = 'mycompiler'
              self.cflags += ['list', 'of', 'all', 'compiler', 'flags']

    The flags that can be set are:
        * :data:`self.cc`
        * :data:`self.cflag`
        * :data:`self.ldflags`
        * :data:`self.include_dirs`
        * :data:`self.libraries`
        * :data:`self.library_dirs`
        * :data:`self.defines`
        * :data:`self.src_ext`
        * :data:`self.so_ext`
        * :data:`self.undefines`

    Parameters
    ----------
    suffix : str, optional
        The JIT compiler version to be used. For example, assuming ``CC=gcc`` and
        ``suffix='4.9'``, the ``gcc-4.9`` will be used as JIT compiler.
    cpp : bool, optional
        If True, JIT compile using a C++ compiler. Defaults to False.
    mpi : bool, optional
        If True, JIT compile using an MPI compiler. Defaults to False.
    """

    fields = {'cc', 'ld'}

    def __init__(self, **kwargs):
        super(Compiler, self).__init__(**kwargs)

        self.__lookup_cmds__()

        self.suffix = kwargs.get('suffix')
        if not kwargs.get('mpi'):
            self.cc = self.CC if kwargs.get('cpp', False) is False else self.CXX
            self.cc = self.cc if self.suffix is None else ('%s-%s' %
                                                           (self.cc, self.suffix))
        else:
            self.cc = self.MPICC if kwargs.get('cpp', False) is False else self.MPICXX
        self.ld = self.cc  # Wanted by the superclass

        self.cflags = ['-O3', '-g', '-fPIC', '-Wall', '-std=c99']
        self.ldflags = ['-shared']

        self.include_dirs = []
        self.libraries = ['m']
        self.library_dirs = []
        self.defines = []
        self.undefines = []

        self.src_ext = 'c' if kwargs.get('cpp', False) is False else 'cpp'

        if platform.system() == "Linux":
            self.so_ext = '.so'
        elif platform.system() == "Darwin":
            self.so_ext = '.dylib'
        elif platform.system() == "Windows":
            self.so_ext = '.dll'
        else:
            raise NotImplementedError("Unsupported platform %s" % platform)

        if self.suffix is not None:
            try:
                self.version = version.StrictVersion(str(float(self.suffix)))
            except (TypeError, ValueError):
                self.version = version.LooseVersion(self.suffix)
        else:
            # Knowing the version may still be useful to pick supported flags
            self.version = sniff_compiler_version(self.CC)

    @memoized_meth
    def get_jit_dir(self):
        """A deterministic temporary directory for jit-compiled objects."""
        return make_tempdir('jitcache')

    @memoized_meth
    def get_codepy_dir(self):
        """A deterministic temporary directory for the codepy cache."""
        return make_tempdir('codepy')

    def load(self, soname):
        """
        Load a compiled shared object.

        Parameters
        ----------
        soname : str
            Name of the .so file (w/o the suffix).

        Returns
        -------
        obj
            The loaded shared object.
        """
        return npct.load_library(str(self.get_jit_dir().joinpath(soname)), '.')

    def save(self, soname, binary):
        """
        Store a binary into a file within a temporary directory.

        Parameters
        ----------
        soname : str
            Name of the .so file (w/o the suffix).
        binary : obj
            The binary data.
        """
        sofile = self.get_jit_dir().joinpath(soname).with_suffix(self.so_ext)
        if sofile.is_file():
            debug("%s: `%s` was not saved in `%s` as it already exists"
                  % (self, sofile.name, self.get_jit_dir()))
        else:
            with open(str(sofile), 'wb') as f:
                f.write(binary)
            debug("%s: `%s` successfully saved in `%s`"
                  % (self, sofile.name, self.get_jit_dir()))

    def make(self, loc, args):
        """Invoke the ``make`` command from within ``loc`` with arguments ``args``."""
        hash_key = sha1((loc + str(args)).encode()).hexdigest()
        logfile = path.join(self.get_jit_dir(), "%s.log" % hash_key)
        errfile = path.join(self.get_jit_dir(), "%s.err" % hash_key)

        with change_directory(loc):
            with open(logfile, "w") as lf:
                with open(errfile, "w") as ef:

                    command = ['make'] + args
                    lf.write("Compilation command:\n")
                    lf.write(" ".join(command))
                    lf.write("\n\n")
                    try:
                        check_call(command, stderr=ef, stdout=lf)
                    except CalledProcessError as e:
                        raise CompilationError('Command "%s" return error status %d. '
                                               'Unable to compile code.\n'
                                               'Compile log in %s\n'
                                               'Compile errors in %s\n' %
                                               (e.cmd, e.returncode, logfile, errfile))
        debug("Make <%s>" % " ".join(args))

    def jit_compile(self, soname, code):
        """
        JIT compile some source code given as a string.

        This function relies upon codepy's ``compile_from_string``, which performs
        caching of compilation units and avoids potential race conditions due to
        multiple processing trying to compile the same object.

        Parameters
        ----------
        soname : str
            Name of the .so file (w/o the suffix).
        code : str
            The source code to be JIT compiled.
        """
        target = str(self.get_jit_dir().joinpath(soname))
        src_file = "%s.%s" % (target, self.src_ext)

        cache_dir = self.get_codepy_dir().joinpath(soname[:7])
        if configuration['jit-backdoor'] is False:
            # Typically we end up here
            # Make a suite of cache directories based on the soname
            cache_dir.mkdir(parents=True, exist_ok=True)
        else:
            # Warning: dropping `code` on the floor in favor to whatever is written
            # within `src_file`
            try:
                with open(src_file, 'r') as f:
                    code = f.read()
                # Bypass the devito JIT cache
                # Note: can't simply use Python's `mkdtemp()` as, with MPI, different
                # ranks would end up creating different cache dirs
                cache_dir = cache_dir.joinpath('jit-backdoor')
                cache_dir.mkdir(parents=True, exist_ok=True)
            except FileNotFoundError:
                raise ValueError("Trying to use the JIT backdoor for `%s`, but "
                                 "the file isn't present" % src_file)

        # `catch_warnings` suppresses codepy complaining that it's taking
        # too long to acquire the cache lock. This warning can only appear
        # in a multiprocess session, typically (but not necessarily) when
        # many processes are frequently attempting jit-compilation (e.g.,
        # when running the test suite in parallel)
        with warnings.catch_warnings():
            warnings.simplefilter('ignore')

            # Spinlock in case of MPI
            sleep_delay = 0 if configuration['mpi'] else 1
            _, _, _, recompiled = compile_from_string(
                self, target, code, src_file,
                cache_dir=cache_dir,
                debug=configuration['debug-compiler'],
                sleep_delay=sleep_delay)

        return recompiled, src_file

    def __lookup_cmds__(self):
        self.CC = 'unknown'
        self.CXX = 'unknown'
        self.MPICC = 'unknown'
        self.MPICXX = 'unknown'

    def __str__(self):
        return self.__class__.__name__

    def __repr__(self):
        return "JITCompiler[%s]" % self.__class__.__name__

    def __getstate__(self):
        # The superclass would otherwise only return a subset of attributes
        return self.__dict__

    def add_include_dirs(self, dirs):
        self.include_dirs = filter_ordered(self.include_dirs + list(as_tuple(dirs)))

    def add_library_dirs(self, dirs):
        self.library_dirs = filter_ordered(self.library_dirs + list(as_tuple(dirs)))

    def add_libraries(self, libs):
        self.libraries = filter_ordered(self.libraries + list(as_tuple(libs)))

    def add_ldflags(self, flags):
        self.ldflags = filter_ordered(self.ldflags + list(as_tuple(flags)))


class GNUCompiler(Compiler):

    def __init__(self, *args, **kwargs):
        super(GNUCompiler, self).__init__(*args, **kwargs)

        self.cflags += ['-march=native', '-Wno-unused-result', '-Wno-unused-variable',
                        '-Wno-unused-but-set-variable', '--fast-math']

        try:
            if self.version >= version.StrictVersion("4.9.0"):
                # Append the openmp flag regardless of configuration['openmp'],
                # since GCC4.9 and later versions implement OpenMP 4.0, hence
                # they support `#pragma omp simd`
                self.ldflags += ['-fopenmp']
        except (TypeError, ValueError):
            if configuration['openmp']:
                self.ldflags += ['-fopenmp']

    def __lookup_cmds__(self):
        self.CC = 'gcc'
        self.CXX = 'g++'
        self.MPICC = 'mpicc'
        self.MPICXX = 'mpicxx'


class ClangCompiler(Compiler):

    def __init__(self, *args, **kwargs):
        super(ClangCompiler, self).__init__(*args, **kwargs)

        self.cflags += ['-Wno-unused-result', '-Wno-unused-variable', '-ffast-math']

        if configuration['platform'] == NVIDIAX:
            # Clang has offloading support via OpenMP
            self.cflags.remove('-std=c99')
            # TODO: Need a generic -march setup
            # self.cflags += ['-Xopenmp-target', '-march=sm_37']
            self.ldflags += ['-fopenmp', '-fopenmp-targets=nvptx64-nvidia-cuda']
        else:
            if configuration['platform'] in [POWER8, POWER9]:
                # -march isn't supported on power architectures
                self.cflags += ['-mcpu=native']
            else:
                self.cflags += ['-march=native']
            if configuration['openmp']:
                self.ldflags += ['-fopenmp']

    def __lookup_cmds__(self):
        self.CC = 'clang'
        self.CXX = 'clang++'
        self.MPICC = 'mpicc'
        self.MPICXX = 'mpicxx'


class IntelCompiler(Compiler):

    def __init__(self, *args, **kwargs):
        super(IntelCompiler, self).__init__(*args, **kwargs)
        self.cflags += ["-xhost"]
        if configuration['platform'] is SKX:
            # Systematically use 512-bit vectors on skylake
            self.cflags += ["-qopt-zmm-usage=high"]
        try:
            if self.version >= version.StrictVersion("15.0.0"):
                # Append the OpenMP flag regardless of configuration['openmp'],
                # since icc15 and later versions implement OpenMP 4.0, hence
                # they support `#pragma omp simd`
                self.ldflags += ['-qopenmp']
        except (TypeError, ValueError):
            if configuration['openmp']:
                # Note: fopenmp, not qopenmp, is what is needed by icc versions < 15.0
                self.ldflags += ['-fopenmp']

        # Make sure the MPI compiler uses `icc` underneath -- whatever the MPI distro is
        if kwargs.get('mpi'):
            ver = check_output([self.MPICC, "--version"]).decode("utf-8")
            if not ver.startswith("icc"):
                warning("The MPI compiler `%s` doesn't use the Intel "
                        "C/C++ compiler underneath" % self.MPICC)

    def __lookup_cmds__(self):
        self.CC = 'icc'
        self.CXX = 'icpc'

        # On some systems, the Intel distribution of MPI may be available, in
        # which case the MPI compiler may be shipped either as `mpiicc` or `mpicc`.
        # On other systems, there may be no Intel distribution of MPI available,
        # thus the MPI compiler is expected to be the classic `mpicc`. Here,
        # we try to use `mpiicc` first, while `mpicc` is our fallback, which may
        # or may not be an Intel distribution
        try:
            check_output(["mpiicc", "--version"]).decode("utf-8")
            self.MPICC = 'mpiicc'
            self.MPICXX = 'mpiicpc'
        except FileNotFoundError:
            self.MPICC = 'mpicc'
            self.MPICXX = 'mpicxx'


class IntelKNLCompiler(IntelCompiler):

    def __init__(self, *args, **kwargs):
        super(IntelKNLCompiler, self).__init__(*args, **kwargs)
        self.cflags += ["-xMIC-AVX512"]
        if not configuration['openmp']:
            warning("Running on Intel KNL without OpenMP is highly discouraged")


class CustomCompiler(Compiler):
    """
    Custom compiler based on standard environment flags.

    Notes
    -----
    Currently honours CC, CFLAGS and LDFLAGS, with defaults similar to the
    default GNU/gcc settings. If DEVITO_ARCH is enabled, the OpenMP linker
    flags are read from OMP_LDFLAGS or otherwise default to ``-fopenmp``.
    """

    def __init__(self, *args, **kwargs):
        super(CustomCompiler, self).__init__(*args, **kwargs)
        default = '-O3 -g -march=native -fPIC -Wall -std=c99'
        self.cflags = environ.get('CFLAGS', default).split(' ')
        self.ldflags = environ.get('LDFLAGS', '-shared').split(' ')
        if configuration['openmp']:
            self.ldflags += environ.get('OMP_LDFLAGS', '-fopenmp').split(' ')

    def __lookup_cmds__(self):
        self.CC = environ.get('CC', 'gcc')
        self.CXX = environ.get('CXX', 'g++')
        self.MPICC = environ.get('MPICC', 'mpicc')
        self.MPICXX = environ.get('MPICXX', 'mpicxx')


compiler_registry = {
    'custom': CustomCompiler,
    'gnu': GNUCompiler,
    'gcc': GNUCompiler,
    'clang': ClangCompiler,
    'osx': ClangCompiler,
    'intel': IntelCompiler,
    'icpc': IntelCompiler,
    'icc': IntelCompiler,
    'intel-knl': IntelKNLCompiler,
    'knl': IntelKNLCompiler,
}
"""
Registry dict for deriving Compiler classes according to the environment variable
DEVITO_ARCH. Developers should add new compiler classes here.
"""
compiler_registry.update({'gcc-%s' % i: partial(GNUCompiler, suffix=i)
                          for i in ['4.9', '5', '6', '7', '8', '9']})