Excluding other unused environments like Node.js makes the support code
about 4 KB smaller.
(cherry picked from commit e818b51f32
)
160 lines
6.1 KiB
Python
160 lines
6.1 KiB
Python
import os
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def is_active():
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return True
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def get_name():
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return 'JavaScript'
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def can_build():
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return 'EM_CONFIG' in os.environ or os.path.exists(os.path.expanduser('~/.emscripten'))
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def get_opts():
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from SCons.Variables import BoolVariable
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return [
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# eval() can be a security concern, so it can be disabled.
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BoolVariable('javascript_eval', 'Enable JavaScript eval interface', True),
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]
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def get_flags():
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return [
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('tools', False),
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('builtin_pcre2_with_jit', False),
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# Disabling the mbedtls module reduces file size.
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# The module has little use due to the limited networking functionality
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# in this platform. For the available networking methods, the browser
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# manages TLS.
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('module_mbedtls_enabled', False),
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]
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def configure(env):
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## Build type
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if env['target'] != 'debug':
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# Use -Os to prioritize optimizing for reduced file size. This is
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# particularly valuable for the web platform because it directly
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# decreases download time.
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# -Os reduces file size by around 5 MiB over -O3. -Oz only saves about
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# 100 KiB over -Os, which does not justify the negative impact on
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# run-time performance.
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env.Append(CCFLAGS=['-Os'])
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env.Append(LINKFLAGS=['-Os'])
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if env['target'] == 'release_debug':
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env.Append(CPPDEFINES=['DEBUG_ENABLED'])
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# Retain function names for backtraces at the cost of file size.
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env.Append(LINKFLAGS=['--profiling-funcs'])
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else:
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env.Append(CPPDEFINES=['DEBUG_ENABLED'])
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env.Append(CCFLAGS=['-O1', '-g'])
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env.Append(LINKFLAGS=['-O1', '-g'])
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env.Append(LINKFLAGS=['-s', 'ASSERTIONS=1'])
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## Compiler configuration
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env['ENV'] = os.environ
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em_config_file = os.getenv('EM_CONFIG') or os.path.expanduser('~/.emscripten')
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if not os.path.exists(em_config_file):
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raise RuntimeError("Emscripten configuration file '%s' does not exist" % em_config_file)
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with open(em_config_file) as f:
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em_config = {}
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try:
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# Emscripten configuration file is a Python file with simple assignments.
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exec(f.read(), em_config)
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except StandardError as e:
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raise RuntimeError("Emscripten configuration file '%s' is invalid:\n%s" % (em_config_file, e))
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if 'BINARYEN_ROOT' in em_config and os.path.isdir(os.path.join(em_config.get('BINARYEN_ROOT'), 'emscripten')):
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# New style, emscripten path as a subfolder of BINARYEN_ROOT
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env.PrependENVPath('PATH', os.path.join(em_config.get('BINARYEN_ROOT'), 'emscripten'))
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elif 'EMSCRIPTEN_ROOT' in em_config:
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# Old style (but can be there as a result from previous activation, so do last)
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env.PrependENVPath('PATH', em_config.get('EMSCRIPTEN_ROOT'))
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else:
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raise RuntimeError("'BINARYEN_ROOT' or 'EMSCRIPTEN_ROOT' missing in Emscripten configuration file '%s'" % em_config_file)
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env['CC'] = 'emcc'
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env['CXX'] = 'em++'
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env['LINK'] = 'emcc'
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env['AR'] = 'emar'
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env['RANLIB'] = 'emranlib'
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# Use TempFileMunge since some AR invocations are too long for cmd.exe.
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# Use POSIX-style paths, required with TempFileMunge.
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env['ARCOM_POSIX'] = env['ARCOM'].replace(
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'$TARGET', '$TARGET.posix').replace(
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'$SOURCES', '$SOURCES.posix')
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env['ARCOM'] = '${TEMPFILE(ARCOM_POSIX)}'
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# All intermediate files are just LLVM bitcode.
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env['OBJPREFIX'] = ''
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env['OBJSUFFIX'] = '.bc'
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env['PROGPREFIX'] = ''
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# Program() output consists of multiple files, so specify suffixes manually at builder.
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env['PROGSUFFIX'] = ''
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env['LIBPREFIX'] = 'lib'
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env['LIBSUFFIX'] = '.bc'
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env['LIBPREFIXES'] = ['$LIBPREFIX']
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env['LIBSUFFIXES'] = ['$LIBSUFFIX']
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## Compile flags
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env.Prepend(CPPPATH=['#platform/javascript'])
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env.Append(CPPDEFINES=['JAVASCRIPT_ENABLED', 'UNIX_ENABLED'])
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# No multi-threading (SharedArrayBuffer) available yet,
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# once feasible also consider memory buffer size issues.
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env.Append(CPPDEFINES=['NO_THREADS'])
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# Disable exceptions and rtti on non-tools (template) builds
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if not env['tools']:
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# These flags help keep the file size down.
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env.Append(CCFLAGS=['-fno-exceptions', '-fno-rtti'])
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# Don't use dynamic_cast, necessary with no-rtti.
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env.Append(CPPDEFINES=['NO_SAFE_CAST'])
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if env['javascript_eval']:
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env.Append(CPPDEFINES=['JAVASCRIPT_EVAL_ENABLED'])
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## Link flags
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# We use IDBFS in javascript_main.cpp. Since Emscripten 1.39.1 it needs to
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# be linked explicitly.
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env.Append(LIBS=['idbfs.js'])
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env.Append(LINKFLAGS=['-s', 'BINARYEN=1'])
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# Only include the JavaScript support code for the web environment
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# (i.e. exclude Node.js and other unused environments).
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# This makes the JavaScript support code about 4 KB smaller.
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env.Append(LINKFLAGS=['-s', 'ENVIRONMENT=web'])
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# This needs to be defined for Emscripten using 'fastcomp' (default pre-1.39.0)
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# and undefined if using 'upstream'. And to make things simple, earlier
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# Emscripten versions didn't include 'fastcomp' in their path, so we check
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# against the presence of 'upstream' to conditionally add the flag.
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if not "upstream" in em_config['EMSCRIPTEN_ROOT']:
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env.Append(LINKFLAGS=['-s', 'BINARYEN_TRAP_MODE=\'clamp\''])
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# Allow increasing memory buffer size during runtime. This is efficient
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# when using WebAssembly (in comparison to asm.js) and works well for
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# us since we don't know requirements at compile-time.
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env.Append(LINKFLAGS=['-s', 'ALLOW_MEMORY_GROWTH=1'])
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# This setting just makes WebGL 2 APIs available, it does NOT disable WebGL 1.
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env.Append(LINKFLAGS=['-s', 'USE_WEBGL2=1'])
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env.Append(LINKFLAGS=['-s', 'INVOKE_RUN=0'])
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# TODO: Reevaluate usage of this setting now that engine.js manages engine runtime.
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env.Append(LINKFLAGS=['-s', 'NO_EXIT_RUNTIME=1'])
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#adding flag due to issue with emscripten 1.38.41 callMain method https://github.com/emscripten-core/emscripten/blob/incoming/ChangeLog.md#v13841-08072019
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env.Append(LINKFLAGS=['-s', 'EXTRA_EXPORTED_RUNTIME_METHODS=["callMain"]'])
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