"""OpenMP wrapper using a libgomp dynamically loaded library."""
from ctypes.util import find_library
from subprocess import check_output, CalledProcessError, DEVNULL
import ctypes
import os
import sys
import sysconfig
try:
# there may be an environ modification when loading config
from pythran.config import compiler
except ImportError:
def compiler():
return os.environ.get('CXX', 'c++')
cxx = compiler()
# This function and the `msvc_runtime_*` ones below are taken over from
# numpy.distutils
def get_shared_lib_extension(is_python_ext=False):
"""Return the correct file extension for shared libraries.
Parameters
----------
is_python_ext : bool, optional
Whether the shared library is a Python extension. Default is False.
Returns
-------
so_ext : str
The shared library extension.
Notes
-----
For Python shared libs, `so_ext` will typically be '.so' on Linux and OS X,
and '.pyd' on Windows. For Python >= 3.2 `so_ext` has a tag prepended on
POSIX systems according to PEP 3149.
"""
confvars = sysconfig.get_config_vars()
so_ext = confvars.get('EXT_SUFFIX', '')
if not is_python_ext:
# hardcode some known values to avoid some old distutils bugs
if (sys.platform.startswith('linux') or
sys.platform.startswith('gnukfreebsd')):
so_ext = '.so'
elif sys.platform.startswith('darwin'):
so_ext = '.dylib'
elif sys.platform.startswith('win'):
so_ext = '.dll'
else:
# don't use long extension (e.g., .cpython-310-x64_64-linux-gnu.so',
# see PEP 3149), but subtract that Python-specific part here
so_ext = so_ext.replace('.' + confvars.get('SOABI'), '', 1)
return so_ext
def msvc_runtime_version():
"Return version of MSVC runtime library, as defined by __MSC_VER__ macro"
msc_pos = sys.version.find('MSC v.')
if msc_pos != -1:
msc_ver = int(sys.version[msc_pos+6:msc_pos+10])
else:
msc_ver = None
return msc_ver
def msvc_runtime_major():
"Return major version of MSVC runtime coded like get_build_msvc_version"
major = {1300: 70, # MSVC 7.0
1310: 71, # MSVC 7.1
1400: 80, # MSVC 8
1500: 90, # MSVC 9 (aka 2008)
1600: 100, # MSVC 10 (aka 2010)
1900: 140, # MSVC 14 (aka 2015)
1910: 141, # MSVC 141 (aka 2017)
1920: 142, # MSVC 142 (aka 2019)
}.get(msvc_runtime_version(), None)
return major
class OpenMP(object):
"""
Internal representation of the OpenMP module.
Custom class is used to dynamically add omp runtime function
to this library when function is called.
"""
def __init__(self):
# FIXME: this is broken, for at least two reasons:
# (1) checking how Python was built is not a good way to determine if
# MSVC is being used right now,
# (2) the `msvc_runtime_major` function above came from
# `numpy.distutils`, where it did not have entries for 1910/1920
# and returned None instead
ver = msvc_runtime_major()
if ver is None:
self.init_not_msvc()
else:
self.init_msvc(ver)
def init_msvc(self, ver):
vcomp_path = find_library('vcomp%d.dll' % ver)
if not vcomp_path:
raise ImportError("I can't find a shared library for vcomp.")
else:
# Load the library (shouldn't fail with an absolute path right?)
self.libomp = ctypes.CDLL(vcomp_path)
self.version = 20
def get_libomp_names(self):
"""Return list of OpenMP libraries to try"""
return ['omp', 'gomp', 'iomp5']
def init_not_msvc(self):
""" Find OpenMP library and try to load if using ctype interface. """
# find_library() does not automatically search LD_LIBRARY_PATH
# until Python 3.6+, so we explicitly add it.
# LD_LIBRARY_PATH is used on Linux, while macOS uses DYLD_LIBRARY_PATH
# and DYLD_FALLBACK_LIBRARY_PATH.
env_vars = []
if sys.platform == 'darwin':
env_vars = ['DYLD_LIBRARY_PATH', 'DYLD_FALLBACK_LIBRARY_PATH']
else:
env_vars = ['LD_LIBRARY_PATH']
paths = []
for env_var in env_vars:
env_paths = os.environ.get(env_var, '')
if env_paths:
paths.extend(env_paths.split(os.pathsep))
libomp_names = self.get_libomp_names()
if cxx is not None:
for libomp_name in libomp_names:
cmd = [cxx,
'-print-file-name=lib{}{}'.format(
libomp_name,
get_shared_lib_extension())]
# The subprocess can fail in various ways, including because it
# doesn't support '-print-file-name'. In that case just give up.
try:
output = check_output(cmd,
stderr=DEVNULL)
path = os.path.dirname(output.decode().strip())
if path:
paths.append(path)
except (OSError, CalledProcessError):
pass
for libomp_name in libomp_names:
# Try to load find libomp shared library using loader search dirs
libomp_path = find_library(libomp_name)
# Try to use custom paths if lookup failed
if not libomp_path:
for path in paths:
candidate_path = os.path.join(
path,
'lib{}{}'.format(libomp_name,
get_shared_lib_extension()))
if os.path.isfile(candidate_path):
libomp_path = candidate_path
break
# Load the library
if libomp_path:
try:
self.libomp = ctypes.CDLL(libomp_path)
except OSError:
raise ImportError("found openMP library '{}' but couldn't load it. "
"This may happen if you are cross-compiling.".format(libomp_path))
self.version = 45
return
raise ImportError("I can't find a shared library for libomp, you may need to install it "
"or adjust the {} environment variable.".format(env_vars[0]))
def __getattr__(self, name):
"""
Get correct function name from libgomp ready to be use.
__getattr__ is call only `name != libomp` as libomp is a real
attribute.
"""
if name == 'VERSION':
return self.version
return getattr(self.libomp, 'omp_' + name)
# see http://mail.python.org/pipermail/python-ideas/2012-May/014969.html
sys.modules[__name__] = OpenMP()
