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- import os
- import sys
- 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),
- # 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 'EMSCRIPTEN_ROOT' not in em_config:
- raise RuntimeError("'EMSCRIPTEN_ROOT' missing in Emscripten configuration file '%s'" % em_config_file)
- env.PrependENVPath('PATH', em_config['EMSCRIPTEN_ROOT'])
- env['CC'] = 'emcc'
- env['CXX'] = 'em++'
- env['LINK'] = 'emcc'
- # Emscripten's ar has issues with duplicate file names, so use cc.
- env['AR'] = 'emcc'
- env['ARFLAGS'] = '-o'
- # emranlib is a noop, so it's safe to use with AR=emcc.
- 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.Append(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'])
- # 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
- env.Append(LINKFLAGS=['-s', 'BINARYEN=1'])
- 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'])
- # Since we use both memory growth and MEMFS preloading,
- # this avoids unecessary copying on start-up.
- env.Append(LINKFLAGS=['--no-heap-copy'])
- # 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'])
- # TODO: Move that to opus module's config.
- if 'module_opus_enabled' in env and env['module_opus_enabled']:
- env.opus_fixed_point = 'yes'
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