"""
Preferences related to C++ compilation
Preferences
--------------------
.. document_brian_prefs:: codegen.cpp
"""
from setuptools import msvc
import distutils
from distutils.ccompiler import get_default_compiler
import json
import os
import re
import platform
import socket
import struct
import subprocess
import sys
import tempfile
from brian2.core.preferences import prefs, BrianPreference
from brian2.utils.filetools import ensure_directory
from brian2.utils.logger import get_logger, std_silent
__all__ = ['get_compiler_and_args', 'get_msvc_env', 'compiler_supports_c99',
'C99Check']
logger = get_logger(__name__)
# default_buildopts stores default build options for Gcc compiler
default_buildopts = []
# Try to get architecture information to get the best compiler setting for
# Windows
msvc_arch_flag = ''
if platform.system() == 'Windows':
flags = None
previously_stored_flags = None
# Check whether we've already stored the CPU flags previously
user_dir = os.path.join(os.path.expanduser('~'), '.brian')
ensure_directory(user_dir)
flag_file = os.path.join(user_dir, 'cpu_flags.txt')
hostname = socket.gethostname()
if os.path.isfile(flag_file):
try:
with open(flag_file, 'r', encoding='utf-8') as f:
previously_stored_flags = json.load(f)
if hostname not in previously_stored_flags:
logger.debug('Ignoring stored CPU flags for a different host')
else:
flags = previously_stored_flags[hostname]
except (IOError, OSError) as ex:
logger.debug(f'Opening file "{flag_file}" to get CPU flags failed with error "{str(ex)}".')
if flags is None: # If we don't have stored info, run get_cpu_flags.py
get_cpu_flags_script = os.path.join(os.path.dirname(__file__),
'get_cpu_flags.py')
get_cpu_flags_script = os.path.abspath(get_cpu_flags_script)
try:
output = subprocess.check_output([sys.executable,
get_cpu_flags_script],
universal_newlines=True,
encoding='utf-8')
flags = json.loads(output)
# Store flags to a file so we don't have to call cpuinfo next time
try:
if previously_stored_flags is not None:
to_store = previously_stored_flags
to_store[hostname] = flags
else:
to_store = {hostname: flags}
with open(flag_file, 'w', encoding='utf-8') as f:
json.dump(to_store, f)
except (IOError, OSError) as ex:
logger.debug(f'Writing file "{flag_file}" to store CPU flags failed with error "{str(ex)}".')
except subprocess.CalledProcessError as ex:
logger.debug(f'Could not determine optimized MSVC flags, get_cpu_flags failed with: {str(ex)}')
if flags is not None:
# Note that this overwrites the arch_flag, i.e. only the best option
# will be used
if 'sse' in flags:
msvc_arch_flag = '/arch:SSE'
if 'sse2' in flags:
msvc_arch_flag = '/arch:SSE2'
if 'avx' in flags:
msvc_arch_flag = '/arch:AVX'
if 'avx2' in flags:
msvc_arch_flag = '/arch:AVX2'
else:
# Optimized default build options for a range a CPU architectures
machine = os.uname().machine
if re.match('^(x86_64|aarch64|arm.*|s390.*|i.86.*)$', machine):
default_buildopts = ['-w', '-O3', '-ffast-math',
'-fno-finite-math-only', '-march=native',
'-std=c++11']
elif re.match('^(alpha|ppc.*|sparc.*)$', machine):
default_buildopts = ['-w', '-O3', '-ffast-math',
'-fno-finite-math-only', '-mcpu=native',
'-mtune=native', '-std=c++11']
elif re.match('^(parisc.*|riscv.*|mips.*)$', machine):
default_buildopts = ['-w', '-O3', '-ffast-math',
'-fno-finite-math-only', '-std=c++11']
else:
default_buildopts = ['-w']
if os.environ.get('READTHEDOCS', 'False').lower() == 'true':
# We are getting imported during a documentation build. Set a fake prefix
# to avoid having the name of the local environment in the documentation
sys_prefix = '/path/to/your/Python/environment'
else:
sys_prefix = sys.prefix
if sys.platform == 'win32':
prefix_dir = os.path.join(sys_prefix, 'Library')
else:
prefix_dir = sys_prefix
# Preferences
prefs.register_preferences(
'codegen.cpp',
'C++ compilation preferences',
compiler = BrianPreference(
default='',
docs="""
Compiler to use (uses default if empty).
Should be ``'unix'`` or ``'msvc'``.
To specify a specific compiler binary on unix systems, set the `CXX` environment
variable instead.
"""
),
extra_compile_args=BrianPreference(
default=None,
validator=lambda v: True,
docs="""
Extra arguments to pass to compiler (if None, use either
``extra_compile_args_gcc`` or ``extra_compile_args_msvc``).
"""
),
extra_compile_args_gcc=BrianPreference(
default=default_buildopts,
docs="""
Extra compile arguments to pass to GCC compiler
"""
),
extra_compile_args_msvc=BrianPreference(
default=['/Ox', '/w', msvc_arch_flag, '/MP'],
docs="""
Extra compile arguments to pass to MSVC compiler (the default
``/arch:`` flag is determined based on the processor architecture)
"""
),
extra_link_args=BrianPreference(
default=[],
docs="""
Any extra platform- and compiler-specific information to use when
linking object files together.
"""
),
include_dirs=BrianPreference(
default=[os.path.join(prefix_dir, 'include')],
docs="""
Include directories to use.
The default value is ``$prefix/include`` (or ``$prefix/Library/include``
on Windows), where ``$prefix`` is Python's site-specific directory
prefix as returned by `sys.prefix`. This will make compilation use
library files installed into a conda environment.
"""
),
library_dirs=BrianPreference(
default=[os.path.join(prefix_dir, 'lib')],
docs="""
List of directories to search for C/C++ libraries at link time.
The default value is ``$prefix/lib`` (or ``$prefix/Library/lib``
on Windows), where ``$prefix`` is Python's site-specific directory
prefix as returned by `sys.prefix`. This will make compilation use
library files installed into a conda environment.
"""
),
runtime_library_dirs=BrianPreference(
default=[os.path.join(prefix_dir, 'lib')]
if sys.platform != 'win32' else [],
docs="""
List of directories to search for C/C++ libraries at run time.
The default value is ``$prefix/lib`` (not used on Windows), where
``$prefix`` is Python's site-specific directory prefix as returned by
`sys.prefix`. This will make compilation use library files installed
into a conda environment.
"""
),
libraries=BrianPreference(
default=[],
docs="""
List of library names (not filenames or paths) to link against.
"""
),
headers=BrianPreference(
default=[],
docs="""
A list of strings specifying header files to use when compiling the
code. The list might look like ["<vector>","'my_header'"]. Note that
the header strings need to be in a form than can be pasted at the end
of a #include statement in the C++ code.
"""
),
define_macros=BrianPreference(
default=[],
docs="""
List of macros to define; each macro is defined using a 2-tuple,
where 'value' is either the string to define it to or None to
define it without a particular value (equivalent of "#define
FOO" in source or -DFOO on Unix C compiler command line).
"""
),
msvc_vars_location=BrianPreference(
default='',
docs="""
Location of the MSVC command line tool (or search for best by default).
"""),
msvc_architecture=BrianPreference(
default='',
docs="""
MSVC architecture name (or use system architectue by default).
Could take values such as x86, amd64, etc.
"""),
)
# check whether compiler supports a flag
# Adapted from https://github.com/pybind/pybind11/
def _determine_flag_compatibility(compiler, flagname):
import tempfile
from distutils.errors import CompileError
with tempfile.NamedTemporaryFile('w', suffix='.cpp') as f, std_silent():
f.write('int main (int argc, char **argv) { return 0; }')
try:
compiler.compile([f.name], extra_postargs=[flagname])
except CompileError:
logger.warn(f"Removing unsupported flag '{flagname}' from "
f'compiler flags.')
return False
return True
_compiler_flag_compatibility = {}
[docs]def has_flag(compiler, flagname):
if compiler.compiler_type == 'msvc':
# MSVC does not raise an error for illegal flags, so determining
# whether it accepts a flag would mean parsing the output for warnings
# This is non-trivial so we don't do it (the main reason to check
# flags in the first place are differences between gcc and clang)
return True
else:
compiler_exe = ' '.join(compiler.executables['compiler_cxx'])
if (compiler_exe, flagname) not in _compiler_flag_compatibility:
compatibility = _determine_flag_compatibility(compiler, flagname)
_compiler_flag_compatibility[(compiler_exe, flagname)] = compatibility
return _compiler_flag_compatibility[(compiler_exe, flagname)]
[docs]def get_compiler_and_args():
"""
Returns the computed compiler and compilation flags
"""
compiler = prefs['codegen.cpp.compiler']
if compiler == '':
compiler = get_default_compiler()
extra_compile_args = prefs['codegen.cpp.extra_compile_args']
if extra_compile_args is None:
if compiler in ('gcc', 'unix'):
extra_compile_args = prefs['codegen.cpp.extra_compile_args_gcc']
elif compiler == 'msvc':
extra_compile_args = prefs['codegen.cpp.extra_compile_args_msvc']
else:
extra_compile_args = []
logger.warn(f"Unsupported compiler '{compiler}'.")
from distutils.ccompiler import new_compiler
from distutils.sysconfig import customize_compiler
compiler_obj = new_compiler(compiler=compiler, verbose=0)
customize_compiler(compiler_obj)
extra_compile_args = [flag
for flag in extra_compile_args
if has_flag(compiler_obj, flag)]
return compiler, extra_compile_args
_msvc_env = None
[docs]def get_msvc_env():
global _msvc_env
arch_name = prefs['codegen.cpp.msvc_architecture']
if arch_name == '':
bits = struct.calcsize('P') * 8
if bits == 64:
arch_name = 'x86_amd64'
else:
arch_name = 'x86'
# Manual specification of vcvarsall.bat location by the user
vcvars_loc = prefs['codegen.cpp.msvc_vars_location']
if vcvars_loc:
vcvars_cmd = f'"{vcvars_loc}" {arch_name}'
return None, vcvars_cmd
# Search for MSVC environment if not already cached
if _msvc_env is None:
try:
_msvc_env = msvc.msvc14_get_vc_env(arch_name)
except distutils.errors.DistutilsPlatformError:
raise IOError("Cannot find Microsoft Visual Studio, You "
"can try to set the path to vcvarsall.bat "
"via the codegen.cpp.msvc_vars_location "
"preference explicitly.")
return _msvc_env, None
_compiler_supports_c99 = None
[docs]def compiler_supports_c99():
global _compiler_supports_c99
if _compiler_supports_c99 is None:
if platform.system() == 'Windows':
fd, tmp_file = tempfile.mkstemp(suffix='.cpp')
os.write(fd, """
#if _MSC_VER < 1800
#error
#endif
""".encode())
os.close(fd)
msvc_env, vcvars_cmd = get_msvc_env()
if vcvars_cmd:
cmd = f'{vcvars_cmd} && cl /E {tmp_file} > NUL 2>&1'
else:
os.environ.update(msvc_env)
cmd = f'cl /E {tmp_file} > NUL 2>&1'
return_value = os.system(cmd)
_compiler_supports_c99 = return_value == 0
os.remove(tmp_file)
else:
cmd = ('echo "#if (__STDC_VERSION__ < 199901L)\n#error\n#endif" | '
'cc -xc -E - > /dev/null 2>&1')
return_value = os.system(cmd)
_compiler_supports_c99 = return_value == 0
return _compiler_supports_c99
[docs]class C99Check(object):
"""
Helper class to create objects that can be passed as an ``availability_check`` to
a `FunctionImplementation`.
"""
def __init__(self, name):
self.name = name
[docs] def __call__(self, *args, **kwargs):
if not compiler_supports_c99():
raise NotImplementedError(f'The "{self.name}" function needs C99 compiler support')