blob: 7c98c387c87052b3199aaed7abba7a26f8fc2945 [file] [log] [blame]
# -*- Python -*-
# Configuration file for 'lit' test runner.
# This file contains common rules for various compiler-rt testsuites.
# It is mostly copied from lit.cfg.py used by Clang.
import os
import platform
import re
import subprocess
import json
import lit.formats
import lit.util
# Choose between lit's internal shell pipeline runner and a real shell. If
# LIT_USE_INTERNAL_SHELL is in the environment, we use that as an override.
use_lit_shell = os.environ.get("LIT_USE_INTERNAL_SHELL")
if use_lit_shell:
# 0 is external, "" is default, and everything else is internal.
execute_external = (use_lit_shell == "0")
else:
# Otherwise we default to internal on Windows and external elsewhere, as
# bash on Windows is usually very slow.
execute_external = (not sys.platform in ['win32'])
# Setup test format.
config.test_format = lit.formats.ShTest(execute_external)
if execute_external:
config.available_features.add('shell')
compiler_id = getattr(config, 'compiler_id', None)
if compiler_id == "Clang":
if platform.system() != 'Windows':
config.cxx_mode_flags = ["--driver-mode=g++"]
else:
config.cxx_mode_flags = []
# We assume that sanitizers should provide good enough error
# reports and stack traces even with minimal debug info.
config.debug_info_flags = ["-gline-tables-only"]
if platform.system() == 'Windows':
# On Windows, use CodeView with column info instead of DWARF. Both VS and
# windbg do not behave well when column info is enabled, but users have
# requested it because it makes ASan reports more precise.
config.debug_info_flags.append("-gcodeview")
config.debug_info_flags.append("-gcolumn-info")
elif compiler_id == 'GNU':
config.cxx_mode_flags = ["-x c++"]
config.debug_info_flags = ["-g"]
else:
lit_config.fatal("Unsupported compiler id: %r" % compiler_id)
# Add compiler ID to the list of available features.
config.available_features.add(compiler_id)
# If needed, add cflag for shadow scale.
if config.asan_shadow_scale != '':
config.target_cflags += " -mllvm -asan-mapping-scale=" + config.asan_shadow_scale
# BFD linker in 64-bit android toolchains fails to find libc++_shared.so, which
# is a transitive shared library dependency (via asan runtime).
if config.android:
# Prepend the flag so that it can be overridden.
config.target_cflags = "-pie -fuse-ld=gold " + config.target_cflags
if config.android_ndk_version < 19:
# With a new compiler and NDK < r19 this flag ends up meaning "link against
# libc++", but NDK r19 makes this mean "link against the stub libstdc++ that
# just contains a handful of ABI functions", which makes most C++ code fail
# to link. In r19 and later we just use the default which is libc++.
config.cxx_mode_flags.append('-stdlib=libstdc++')
config.environment = dict(os.environ)
# Clear some environment variables that might affect Clang.
possibly_dangerous_env_vars = ['ASAN_OPTIONS', 'DFSAN_OPTIONS', 'LSAN_OPTIONS',
'MSAN_OPTIONS', 'UBSAN_OPTIONS',
'COMPILER_PATH', 'RC_DEBUG_OPTIONS',
'CINDEXTEST_PREAMBLE_FILE', 'LIBRARY_PATH',
'CPATH', 'C_INCLUDE_PATH', 'CPLUS_INCLUDE_PATH',
'OBJC_INCLUDE_PATH', 'OBJCPLUS_INCLUDE_PATH',
'LIBCLANG_TIMING', 'LIBCLANG_OBJTRACKING',
'LIBCLANG_LOGGING', 'LIBCLANG_BGPRIO_INDEX',
'LIBCLANG_BGPRIO_EDIT', 'LIBCLANG_NOTHREADS',
'LIBCLANG_RESOURCE_USAGE',
'LIBCLANG_CODE_COMPLETION_LOGGING',
'XRAY_OPTIONS']
# Clang/Win32 may refer to %INCLUDE%. vsvarsall.bat sets it.
if platform.system() != 'Windows':
possibly_dangerous_env_vars.append('INCLUDE')
for name in possibly_dangerous_env_vars:
if name in config.environment:
del config.environment[name]
# Tweak PATH to include llvm tools dir.
if (not config.llvm_tools_dir) or (not os.path.exists(config.llvm_tools_dir)):
lit_config.fatal("Invalid llvm_tools_dir config attribute: %r" % config.llvm_tools_dir)
path = os.path.pathsep.join((config.llvm_tools_dir, config.environment['PATH']))
config.environment['PATH'] = path
# Help MSVS link.exe find the standard libraries.
# Make sure we only try to use it when targetting Windows.
if platform.system() == 'Windows' and '-win' in config.target_triple:
config.environment['LIB'] = os.environ['LIB']
config.available_features.add(config.host_os.lower())
if re.match(r'^x86_64.*-linux', config.target_triple):
config.available_features.add("x86_64-linux")
config.available_features.add("host-byteorder-" + sys.byteorder + "-endian")
if config.have_zlib == "1":
config.available_features.add("zlib")
# Use ugly construction to explicitly prohibit "clang", "clang++" etc.
# in RUN lines.
config.substitutions.append(
(' clang', """\n\n*** Do not use 'clangXXX' in tests,
instead define '%clangXXX' substitution in lit config. ***\n\n""") )
if config.host_os == 'NetBSD':
nb_commands_dir = os.path.join(config.compiler_rt_src_root,
"test", "sanitizer_common", "netbsd_commands")
config.netbsd_noaslr_prefix = ('sh ' +
os.path.join(nb_commands_dir, 'run_noaslr.sh'))
config.netbsd_nomprotect_prefix = ('sh ' +
os.path.join(nb_commands_dir,
'run_nomprotect.sh'))
config.substitutions.append( ('%run_nomprotect',
config.netbsd_nomprotect_prefix) )
else:
config.substitutions.append( ('%run_nomprotect', '%run') )
# Allow tests to be executed on a simulator or remotely.
if config.emulator:
config.substitutions.append( ('%run', config.emulator) )
config.substitutions.append( ('%env ', "env ") )
# TODO: Implement `%device_rm` to perform removal of files in the emulator.
# For now just make it a no-op.
lit_config.warning('%device_rm is not implemented')
config.substitutions.append( ('%device_rm', 'echo ') )
config.compile_wrapper = ""
elif config.host_os == 'Darwin' and config.apple_platform != "osx":
# Darwin tests can be targetting macOS, a device or a simulator. All devices
# are declared as "ios", even for iOS derivatives (tvOS, watchOS). Similarly,
# all simulators are "iossim". See the table below.
#
# =========================================================================
# Target | Feature set
# =========================================================================
# macOS | darwin
# iOS device | darwin, ios
# iOS simulator | darwin, ios, iossim
# tvOS device | darwin, ios, tvos
# tvOS simulator | darwin, ios, iossim, tvos, tvossim
# watchOS device | darwin, ios, watchos
# watchOS simulator | darwin, ios, iossim, watchos, watchossim
# =========================================================================
ios_or_iossim = "iossim" if config.apple_platform.endswith("sim") else "ios"
config.available_features.add('ios')
device_id_env = "SANITIZER_" + ios_or_iossim.upper() + "_TEST_DEVICE_IDENTIFIER"
if ios_or_iossim == "iossim":
config.available_features.add('iossim')
if device_id_env not in os.environ:
lit_config.fatal(
'{} must be set in the environment when running iossim tests'.format(
device_id_env))
if config.apple_platform != "ios" and config.apple_platform != "iossim":
config.available_features.add(config.apple_platform)
ios_commands_dir = os.path.join(config.compiler_rt_src_root, "test", "sanitizer_common", "ios_commands")
run_wrapper = os.path.join(ios_commands_dir, ios_or_iossim + "_run.py")
env_wrapper = os.path.join(ios_commands_dir, ios_or_iossim + "_env.py")
compile_wrapper = os.path.join(ios_commands_dir, ios_or_iossim + "_compile.py")
prepare_script = os.path.join(ios_commands_dir, ios_or_iossim + "_prepare.py")
if device_id_env in os.environ:
config.environment[device_id_env] = os.environ[device_id_env]
config.substitutions.append(('%run', run_wrapper))
config.substitutions.append(('%env ', env_wrapper + " "))
# Current implementation of %device_rm uses the run_wrapper to do
# the work.
config.substitutions.append(('%device_rm', '{} rm '.format(run_wrapper)))
config.compile_wrapper = compile_wrapper
try:
prepare_output = subprocess.check_output([prepare_script, config.apple_platform, config.clang]).decode().strip()
except subprocess.CalledProcessError as e:
print("Command failed:")
print(e.output)
raise e
if len(prepare_output) > 0: print(prepare_output)
prepare_output_json = prepare_output.split("\n")[-1]
prepare_output = json.loads(prepare_output_json)
config.environment.update(prepare_output["env"])
elif config.android:
config.available_features.add('android')
compile_wrapper = os.path.join(config.compiler_rt_src_root, "test", "sanitizer_common", "android_commands", "android_compile.py") + " "
config.compile_wrapper = compile_wrapper
config.substitutions.append( ('%run', "") )
config.substitutions.append( ('%env ', "env ") )
# TODO: Implement `%device_rm` to perform removal of files on a device. For
# now just make it a no-op.
lit_config.warning('%device_rm is not implemented')
config.substitutions.append( ('%device_rm', 'echo ') )
else:
config.substitutions.append( ('%run', "") )
config.substitutions.append( ('%env ', "env ") )
# When running locally %device_rm is a no-op.
config.substitutions.append( ('%device_rm', 'echo ') )
config.compile_wrapper = ""
# Define CHECK-%os to check for OS-dependent output.
config.substitutions.append( ('CHECK-%os', ("CHECK-" + config.host_os)))
# Define %arch to check for architecture-dependent output.
config.substitutions.append( ('%arch', (config.host_arch)))
if config.host_os == 'Windows':
# FIXME: This isn't quite right. Specifically, it will succeed if the program
# does not crash but exits with a non-zero exit code. We ought to merge
# KillTheDoctor and not --crash to make the latter more useful and remove the
# need for this substitution.
config.expect_crash = "not KillTheDoctor "
else:
config.expect_crash = "not --crash "
config.substitutions.append( ("%expect_crash ", config.expect_crash) )
target_arch = getattr(config, 'target_arch', None)
if target_arch:
config.available_features.add(target_arch + '-target-arch')
if target_arch in ['x86_64', 'i386']:
config.available_features.add('x86-target-arch')
config.available_features.add(target_arch + '-' + config.host_os.lower())
compiler_rt_debug = getattr(config, 'compiler_rt_debug', False)
if not compiler_rt_debug:
config.available_features.add('compiler-rt-optimized')
libdispatch = getattr(config, 'compiler_rt_intercept_libdispatch', False)
if libdispatch:
config.available_features.add('libdispatch')
sanitizer_can_use_cxxabi = getattr(config, 'sanitizer_can_use_cxxabi', True)
if sanitizer_can_use_cxxabi:
config.available_features.add('cxxabi')
if config.has_lld:
config.available_features.add('lld-available')
if config.use_lld:
config.available_features.add('lld')
if config.can_symbolize:
config.available_features.add('can-symbolize')
if config.gwp_asan:
config.available_features.add('gwp_asan')
lit.util.usePlatformSdkOnDarwin(config, lit_config)
# Maps a lit substitution name for the minimum target OS flag
# to the macOS version that first contained the relevant feature.
darwin_min_deployment_target_substitutions = {
'%macos_min_target_10_11': '10.11',
# rdar://problem/22207160
'%darwin_min_target_with_full_runtime_arc_support': '10.11',
'%darwin_min_target_with_tls_support': '10.12',
}
if config.host_os == 'Darwin':
def get_apple_platform_version_aligned_with(macos_version, apple_platform):
"""
Given a macOS version (`macos_version`) returns the corresponding version for
the specified Apple platform if it exists.
`macos_version` - The macOS version as a string.
`apple_platform` - The Apple platform name as a string.
Returns the corresponding version as a string if it exists, otherwise
`None` is returned.
"""
m = re.match(r'^10\.(?P<min>\d+)(\.(?P<patch>\d+))?$', macos_version)
if not m:
raise Exception('Could not parse macOS version: "{}"'.format(macos_version))
ver_min = int(m.group('min'))
ver_patch = m.group('patch')
if ver_patch:
ver_patch = int(ver_patch)
else:
ver_patch = 0
result_str = ''
if apple_platform == 'osx':
# Drop patch for now.
result_str = '10.{}'.format(ver_min)
elif apple_platform.startswith('ios') or apple_platform.startswith('tvos'):
result_maj = ver_min - 2
if result_maj < 1:
return None
result_str = '{}.{}'.format(result_maj, ver_patch)
elif apple_platform.startswith('watch'):
result_maj = ver_min - 9
if result_maj < 1:
return None
result_str = '{}.{}'.format(result_maj, ver_patch)
else:
raise Exception('Unsuported apple platform "{}"'.format(apple_platform))
return result_str
osx_version = (10, 0, 0)
try:
osx_version = subprocess.check_output(["sw_vers", "-productVersion"],
universal_newlines=True)
osx_version = tuple(int(x) for x in osx_version.split('.'))
if len(osx_version) == 2: osx_version = (osx_version[0], osx_version[1], 0)
if osx_version >= (10, 11):
config.available_features.add('osx-autointerception')
config.available_features.add('osx-ld64-live_support')
else:
# The ASAN initialization-bug.cpp test should XFAIL on OS X systems
# older than El Capitan. By marking the test as being unsupported with
# this "feature", we can pass the test on newer OS X versions and other
# platforms.
config.available_features.add('osx-no-ld64-live_support')
except subprocess.CalledProcessError:
pass
config.darwin_osx_version = osx_version
# Detect x86_64h
try:
output = subprocess.check_output(["sysctl", "hw.cpusubtype"])
output_re = re.match("^hw.cpusubtype: ([0-9]+)$", output)
if output_re:
cpu_subtype = int(output_re.group(1))
if cpu_subtype == 8: # x86_64h
config.available_features.add('x86_64h')
except:
pass
def get_apple_min_deploy_target_flag_aligned_with_osx(version):
min_os_aligned_with_osx_v = get_apple_platform_version_aligned_with(version, config.apple_platform)
min_os_aligned_with_osx_v_flag = ''
if min_os_aligned_with_osx_v:
min_os_aligned_with_osx_v_flag = '{flag}={version}'.format(
flag=config.apple_platform_min_deployment_target_flag,
version=min_os_aligned_with_osx_v)
else:
lit_config.warning('Could not find a version of {} that corresponds with macOS {}'.format(
config.apple_platform,
version))
return min_os_aligned_with_osx_v_flag
for substitution, osx_version in darwin_min_deployment_target_substitutions.items():
config.substitutions.append( (substitution, get_apple_min_deploy_target_flag_aligned_with_osx(osx_version)) )
# 32-bit iOS simulator is deprecated and removed in latest Xcode.
if config.apple_platform == "iossim":
if config.target_arch == "i386":
config.unsupported = True
else:
for substitution in darwin_min_deployment_target_substitutions.keys():
config.substitutions.append( (substitution, "") )
if config.android:
env = os.environ.copy()
if config.android_serial:
env['ANDROID_SERIAL'] = config.android_serial
config.environment['ANDROID_SERIAL'] = config.android_serial
adb = os.environ.get('ADB', 'adb')
try:
android_api_level_str = subprocess.check_output([adb, "shell", "getprop", "ro.build.version.sdk"], env=env).rstrip()
except (subprocess.CalledProcessError, OSError):
lit_config.fatal("Failed to read ro.build.version.sdk (using '%s' as adb)" % adb)
try:
android_api_level = int(android_api_level_str)
except ValueError:
lit_config.fatal("Failed to read ro.build.version.sdk (using '%s' as adb): got '%s'" % (adb, android_api_level_str))
if android_api_level >= 26:
config.available_features.add('android-26')
if android_api_level >= 28:
config.available_features.add('android-28')
# Prepare the device.
android_tmpdir = '/data/local/tmp/Output'
subprocess.check_call([adb, "shell", "mkdir", "-p", android_tmpdir], env=env)
for file in config.android_files_to_push:
subprocess.check_call([adb, "push", file, android_tmpdir], env=env)
if config.host_os == 'Linux':
# detect whether we are using glibc, and which version
# NB: 'ldd' is just one of the tools commonly installed as part of glibc
ldd_ver_cmd = subprocess.Popen(['ldd', '--version'],
stdout=subprocess.PIPE,
env={'LANG': 'C'})
sout, _ = ldd_ver_cmd.communicate()
ver_line = sout.splitlines()[0]
if ver_line.startswith(b"ldd "):
from distutils.version import LooseVersion
ver = LooseVersion(ver_line.split()[-1].decode())
# 2.27 introduced some incompatibilities
if ver >= LooseVersion("2.27"):
config.available_features.add("glibc-2.27")
sancovcc_path = os.path.join(config.llvm_tools_dir, "sancov")
if os.path.exists(sancovcc_path):
config.available_features.add("has_sancovcc")
config.substitutions.append( ("%sancovcc ", sancovcc_path) )
def is_darwin_lto_supported():
return os.path.exists(os.path.join(config.llvm_shlib_dir, 'libLTO.dylib'))
def is_linux_lto_supported():
if config.use_lld:
return True
if not os.path.exists(os.path.join(config.llvm_shlib_dir, 'LLVMgold.so')):
return False
ld_cmd = subprocess.Popen([config.gold_executable, '--help'], stdout = subprocess.PIPE, env={'LANG': 'C'})
ld_out = ld_cmd.stdout.read().decode()
ld_cmd.wait()
if not '-plugin' in ld_out:
return False
return True
def is_windows_lto_supported():
return os.path.exists(os.path.join(config.llvm_tools_dir, 'lld-link.exe'))
if config.host_os == 'Darwin' and is_darwin_lto_supported():
config.lto_supported = True
config.lto_launch = ["env", "DYLD_LIBRARY_PATH=" + config.llvm_shlib_dir]
config.lto_flags = []
elif config.host_os in ['Linux', 'FreeBSD', 'NetBSD'] and is_linux_lto_supported():
config.lto_supported = True
config.lto_launch = []
if config.use_lld:
config.lto_flags = ["-fuse-ld=lld"]
else:
config.lto_flags = ["-fuse-ld=gold"]
elif config.host_os == 'Windows' and is_windows_lto_supported():
config.lto_supported = True
config.lto_launch = []
config.lto_flags = ["-fuse-ld=lld"]
else:
config.lto_supported = False
if config.lto_supported:
config.available_features.add('lto')
if config.use_thinlto:
config.available_features.add('thinlto')
config.lto_flags += ["-flto=thin"]
else:
config.lto_flags += ["-flto"]
if config.use_newpm:
config.lto_flags += ["-fexperimental-new-pass-manager"]
if config.have_rpc_xdr_h:
config.available_features.add('sunrpc')
# Ask llvm-config about assertion mode.
try:
llvm_config_cmd = subprocess.Popen(
[os.path.join(config.llvm_tools_dir, 'llvm-config'), '--assertion-mode'],
stdout = subprocess.PIPE,
env=config.environment)
except OSError as e:
print("Could not launch llvm-config in " + config.llvm_tools_dir)
print(" Failed with error #{0}: {1}".format(e.errno, e.strerror))
exit(42)
if re.search(r'ON', llvm_config_cmd.stdout.read().decode('ascii')):
config.available_features.add('asserts')
llvm_config_cmd.wait()
# Sanitizer tests tend to be flaky on Windows due to PR24554, so add some
# retries. We don't do this on otther platforms because it's slower.
if platform.system() == 'Windows':
config.test_retry_attempts = 2
# No throttling on non-Darwin platforms.
lit_config.parallelism_groups['shadow-memory'] = None
if platform.system() == 'Darwin':
ios_device = config.apple_platform != 'osx' and not config.apple_platform.endswith('sim')
# Force sequential execution when running tests on iOS devices.
if ios_device:
lit_config.warning('Forcing sequential execution for iOS device tests')
lit_config.parallelism_groups['ios-device'] = 1
config.parallelism_group = 'ios-device'
# Only run up to 3 processes that require shadow memory simultaneously on
# 64-bit Darwin. Using more scales badly and hogs the system due to
# inefficient handling of large mmap'd regions (terabytes) by the kernel.
elif config.target_arch in ['x86_64', 'x86_64h']:
lit_config.warning('Throttling sanitizer tests that require shadow memory on Darwin 64bit')
lit_config.parallelism_groups['shadow-memory'] = 3
# Multiple substitutions are necessary to support multiple shared objects used
# at once.
# Note that substitutions with numbers have to be defined first to avoid
# being subsumed by substitutions with smaller postfix.
for postfix in ["2", "1", ""]:
if config.host_os == 'Darwin':
config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, '-Wl,-rpath,@executable_path/ %dynamiclib' + postfix) )
config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '-install_name @rpath/`basename %dynamiclib{}`'.format(postfix)) )
elif config.host_os in ('FreeBSD', 'NetBSD', 'OpenBSD'):
config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, "-Wl,-z,origin -Wl,-rpath,\$ORIGIN -L%T -l%xdynamiclib_namespec" + postfix) )
config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '') )
elif config.host_os == 'Linux':
config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, "-Wl,-rpath,\$ORIGIN -L%T -l%xdynamiclib_namespec" + postfix) )
config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '') )
elif config.host_os == 'SunOS':
config.substitutions.append( ("%ld_flags_rpath_exe" + postfix, "-Wl,-R\$ORIGIN -L%T -l%xdynamiclib_namespec" + postfix) )
config.substitutions.append( ("%ld_flags_rpath_so" + postfix, '') )
# Must be defined after the substitutions that use %dynamiclib.
config.substitutions.append( ("%dynamiclib" + postfix, '%T/%xdynamiclib_filename' + postfix) )
config.substitutions.append( ("%xdynamiclib_filename" + postfix, 'lib%xdynamiclib_namespec{}.so'.format(postfix)) )
config.substitutions.append( ("%xdynamiclib_namespec", '%basename_t.dynamic') )
# Provide a substituion that can be used to tell Clang to use a static libstdc++.
# The substitution expands to nothing on non Linux platforms.
# FIXME: This should check the target OS, not the host OS.
if config.host_os == 'Linux':
config.substitutions.append( ("%linux_static_libstdcplusplus", "-stdlib=libstdc++ -static-libstdc++") )
else:
config.substitutions.append( ("%linux_static_libstdcplusplus", "") )
config.default_sanitizer_opts = []
if config.host_os == 'Darwin':
# On Darwin, we default to `abort_on_error=1`, which would make tests run
# much slower. Let's override this and run lit tests with 'abort_on_error=0'.
config.default_sanitizer_opts += ['abort_on_error=0']
config.default_sanitizer_opts += ['log_to_syslog=0']
if lit.util.which('log'):
# Querying the log can only done by a privileged user so
# so check if we can query the log.
exit_code = -1
with open('/dev/null', 'r') as f:
# Run a `log show` command the should finish fairly quickly and produce very little output.
exit_code = subprocess.call(['log', 'show', '--last', '1m', '--predicate', '1 == 0'], stdout=f, stderr=f)
if exit_code == 0:
config.available_features.add('darwin_log_cmd')
else:
lit_config.warning('log command found but cannot queried')
else:
lit_config.warning('log command not found. Some tests will be skipped.')
elif config.android:
config.default_sanitizer_opts += ['abort_on_error=0']
# Allow tests to use REQUIRES=stable-runtime. For use when you cannot use XFAIL
# because the test hangs or fails on one configuration and not the other.
if config.android or (config.target_arch not in ['arm', 'armhf', 'aarch64']):
config.available_features.add('stable-runtime')
if config.asan_shadow_scale:
config.available_features.add("shadow-scale-%s" % config.asan_shadow_scale)
else:
config.available_features.add("shadow-scale-3")
if config.expensive_checks:
config.available_features.add("expensive_checks")
# Propagate the LLD/LTO into the clang config option, so nothing else is needed.
run_wrapper = []
target_cflags = [getattr(config, 'target_cflags', None)]
extra_cflags = []
if config.use_lto and config.lto_supported:
run_wrapper += config.lto_launch
extra_cflags += config.lto_flags
elif config.use_lto and (not config.lto_supported):
config.unsupported = True
if config.use_lld and config.has_lld and not config.use_lto:
extra_cflags += ["-fuse-ld=lld"]
elif config.use_lld and (not config.has_lld):
config.unsupported = True
config.clang = " " + " ".join(run_wrapper + [config.compile_wrapper, config.clang]) + " "
config.target_cflags = " " + " ".join(target_cflags + extra_cflags) + " "