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), # 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']) # 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'])