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import os
def is_active():
return True
def get_name():
return 'JavaScript'
def can_build():
return 'EM_CONFIG' in os.environ or os.path.exists(os.path.expanduser('~/.emscripten'))
def get_opts():
from SCons.Variables import BoolVariable
return [
# eval() can be a security concern, so it can be disabled.
BoolVariable('javascript_eval', 'Enable JavaScript eval interface', True),
]
def get_flags():
return [
('tools', False),
('builtin_pcre2_with_jit', False),
# Disabling the mbedtls module reduces file size.
# The module has little use due to the limited networking functionality
# in this platform. For the available networking methods, the browser
# manages TLS.
('module_mbedtls_enabled', False),
]
def configure(env):
## Build type
if env['target'] != 'debug':
# Use -Os to prioritize optimizing for reduced file size. This is
# particularly valuable for the web platform because it directly
# decreases download time.
# -Os reduces file size by around 5 MiB over -O3. -Oz only saves about
# 100 KiB over -Os, which does not justify the negative impact on
# run-time performance.
env.Append(CCFLAGS=['-Os'])
env.Append(LINKFLAGS=['-Os'])
if env['target'] == 'release_debug':
env.Append(CPPDEFINES=['DEBUG_ENABLED'])
# Retain function names for backtraces at the cost of file size.
env.Append(LINKFLAGS=['--profiling-funcs'])
else:
env.Append(CPPDEFINES=['DEBUG_ENABLED'])
env.Append(CCFLAGS=['-O1', '-g'])
env.Append(LINKFLAGS=['-O1', '-g'])
env.Append(LINKFLAGS=['-s', 'ASSERTIONS=1'])
## Compiler configuration
env['ENV'] = os.environ
em_config_file = os.getenv('EM_CONFIG') or os.path.expanduser('~/.emscripten')
if not os.path.exists(em_config_file):
raise RuntimeError("Emscripten configuration file '%s' does not exist" % em_config_file)
with open(em_config_file) as f:
em_config = {}
try:
# Emscripten configuration file is a Python file with simple assignments.
exec(f.read(), em_config)
except StandardError as e:
raise RuntimeError("Emscripten configuration file '%s' is invalid:\n%s" % (em_config_file, e))
if 'BINARYEN_ROOT' in em_config and os.path.isdir(os.path.join(em_config.get('BINARYEN_ROOT'), 'emscripten')):
# New style, emscripten path as a subfolder of BINARYEN_ROOT
env.PrependENVPath('PATH', os.path.join(em_config.get('BINARYEN_ROOT'), 'emscripten'))
elif 'EMSCRIPTEN_ROOT' in em_config:
# Old style (but can be there as a result from previous activation, so do last)
env.PrependENVPath('PATH', em_config.get('EMSCRIPTEN_ROOT'))
else:
raise RuntimeError("'BINARYEN_ROOT' or 'EMSCRIPTEN_ROOT' missing in Emscripten configuration file '%s'" % em_config_file)
env['CC'] = 'emcc'
env['CXX'] = 'em++'
env['LINK'] = 'emcc'
env['AR'] = 'emar'
env['RANLIB'] = 'emranlib'
# Use TempFileMunge since some AR invocations are too long for cmd.exe.
# Use POSIX-style paths, required with TempFileMunge.
env['ARCOM_POSIX'] = env['ARCOM'].replace(
'$TARGET', '$TARGET.posix').replace(
'$SOURCES', '$SOURCES.posix')
env['ARCOM'] = '${TEMPFILE(ARCOM_POSIX)}'
# All intermediate files are just LLVM bitcode.
env['OBJPREFIX'] = ''
env['OBJSUFFIX'] = '.bc'
env['PROGPREFIX'] = ''
# Program() output consists of multiple files, so specify suffixes manually at builder.
env['PROGSUFFIX'] = ''
env['LIBPREFIX'] = 'lib'
env['LIBSUFFIX'] = '.bc'
env['LIBPREFIXES'] = ['$LIBPREFIX']
env['LIBSUFFIXES'] = ['$LIBSUFFIX']
## Compile flags
env.Prepend(CPPPATH=['#platform/javascript'])
env.Append(CPPDEFINES=['JAVASCRIPT_ENABLED', 'UNIX_ENABLED'])
# No multi-threading (SharedArrayBuffer) available yet,
# once feasible also consider memory buffer size issues.
env.Append(CPPDEFINES=['NO_THREADS'])
# Disable exceptions and rtti on non-tools (template) builds
if not env['tools']:
# These flags help keep the file size down.
env.Append(CCFLAGS=['-fno-exceptions', '-fno-rtti'])
# Don't use dynamic_cast, necessary with no-rtti.
env.Append(CPPDEFINES=['NO_SAFE_CAST'])
if env['javascript_eval']:
env.Append(CPPDEFINES=['JAVASCRIPT_EVAL_ENABLED'])
## Link flags
# We use IDBFS in javascript_main.cpp. Since Emscripten 1.39.1 it needs to
# be linked explicitly.
env.Append(LIBS=['idbfs.js'])
env.Append(LINKFLAGS=['-s', 'BINARYEN=1'])
# Only include the JavaScript support code for the web environment
# (i.e. exclude Node.js and other unused environments).
# This makes the JavaScript support code about 4 KB smaller.
env.Append(LINKFLAGS=['-s', 'ENVIRONMENT=web'])
# This needs to be defined for Emscripten using 'fastcomp' (default pre-1.39.0)
# and undefined if using 'upstream'. And to make things simple, earlier
# Emscripten versions didn't include 'fastcomp' in their path, so we check
# against the presence of 'upstream' to conditionally add the flag.
if not "upstream" in em_config['EMSCRIPTEN_ROOT']:
env.Append(LINKFLAGS=['-s', 'BINARYEN_TRAP_MODE=\'clamp\''])
# Allow increasing memory buffer size during runtime. This is efficient
# when using WebAssembly (in comparison to asm.js) and works well for
# us since we don't know requirements at compile-time.
env.Append(LINKFLAGS=['-s', 'ALLOW_MEMORY_GROWTH=1'])
# This setting just makes WebGL 2 APIs available, it does NOT disable WebGL 1.
env.Append(LINKFLAGS=['-s', 'USE_WEBGL2=1'])
env.Append(LINKFLAGS=['-s', 'INVOKE_RUN=0'])
# TODO: Reevaluate usage of this setting now that engine.js manages engine runtime.
env.Append(LINKFLAGS=['-s', 'NO_EXIT_RUNTIME=1'])
#adding flag due to issue with emscripten 1.38.41 callMain method https://github.com/emscripten-core/emscripten/blob/incoming/ChangeLog.md#v13841-08072019
env.Append(LINKFLAGS=['-s', 'EXTRA_EXPORTED_RUNTIME_METHODS=["callMain"]'])
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