text: #!/usr/bin/env python2
  # Copyright 2011 The Emscripten Authors.  All rights reserved.
  # Emscripten is available under two separate licenses, the MIT license and the
  # University of Illinois/NCSA Open Source License.  Both these licenses can be
  # found in the LICENSE file.
  
  """emcc - compiler helper script
  =============================
  
  emcc is a drop-in replacement for a compiler like gcc or clang.
  
  See  emcc --help  for details.
  
  emcc can be influenced by a few environment variables:
  
    EMCC_DEBUG - "1" will log out useful information during compilation, as well as
                 save each compiler step as an emcc-* file in the temp dir
                 (by default /tmp/emscripten_temp). "2" will save additional emcc-*
                 steps, that would normally not be separately produced (so this
                 slows down compilation).
  
    EMMAKEN_NO_SDK - Will tell emcc *not* to use the emscripten headers. Instead
                     your system headers will be used.
  
    EMMAKEN_COMPILER - The compiler to be used, if you don't want the default clang.
  """
  
  from __future__ import print_function
  
  import json
  import logging
  import os
  import re
  import shlex
  import shutil
  import stat
  import sys
  import time
  from subprocess import PIPE
  
  import emscripten
  from tools import shared, system_libs, client_mods, js_optimizer, jsrun, colored_logger
  from tools.shared import unsuffixed, unsuffixed_basename, WINDOWS, safe_copy, safe_move, run_process, asbytes, read_and_preprocess, exit_with_error, DEBUG
  from tools.response_file import substitute_response_files
  import tools.line_endings
  from tools.toolchain_profiler import ToolchainProfiler
  if __name__ == '__main__':
    ToolchainProfiler.record_process_start()
  
  try:
    from urllib.parse import quote
  except ImportError:
    # Python 2 compatibility
    from urllib import quote
  
  logger = logging.getLogger('emcc')
  
  # endings = dot + a suffix, safe to test by  filename.endswith(endings)
  C_ENDINGS = ('.c', '.C', '.i')
  CXX_ENDINGS = ('.cpp', '.cxx', '.cc', '.c++', '.CPP', '.CXX', '.CC', '.C++', '.ii')
  OBJC_ENDINGS = ('.m', '.mi')
  OBJCXX_ENDINGS = ('.mm', '.mii')
  SPECIAL_ENDINGLESS_FILENAMES = ('/dev/null',)
  
  SOURCE_ENDINGS = C_ENDINGS + CXX_ENDINGS + OBJC_ENDINGS + OBJCXX_ENDINGS + SPECIAL_ENDINGLESS_FILENAMES
  C_ENDINGS = C_ENDINGS + SPECIAL_ENDINGLESS_FILENAMES # consider the special endingless filenames like /dev/null to be C
  
  JS_CONTAINING_ENDINGS = ('.js', '.mjs', '.html')
  OBJECT_FILE_ENDINGS = ('.bc', '.o', '.obj', '.lo')
  DYNAMICLIB_ENDINGS = ('.dylib', '.so') # Windows .dll suffix is not included in this list, since those are never linked to directly on the command line.
  STATICLIB_ENDINGS = ('.a',)
  ASSEMBLY_ENDINGS = ('.ll',)
  HEADER_ENDINGS = ('.h', '.hxx', '.hpp', '.hh', '.H', '.HXX', '.HPP', '.HH')
  WASM_ENDINGS = ('.wasm', '.wast')
  
  SUPPORTED_LINKER_FLAGS = (
      '--start-group', '--end-group',
      '-(', '-)',
      '--whole-archive', '--no-whole-archive',
      '-whole-archive', '-no-whole-archive')
  
  LIB_PREFIXES = ('', 'lib')
  
  DEFERRED_RESPONSE_FILES = ('EMTERPRETIFY_BLACKLIST', 'EMTERPRETIFY_WHITELIST', 'EMTERPRETIFY_SYNCLIST')
  
  # Mapping of emcc opt levels to llvm opt levels. We use llvm opt level 3 in emcc
  # opt levels 2 and 3 (emcc 3 is unsafe opts, so unsuitable for the only level to
  # get llvm opt level 3, and speed-wise emcc level 2 is already the slowest/most
  # optimizing level)
  LLVM_OPT_LEVEL = {
    0: ['-O0'],
    1: ['-O1'],
    2: ['-O3'],
    3: ['-O3'],
  }
  
  # Do not compile .ll files into .bc, just compile them with emscripten directly
  # Not recommended, this is mainly for the test runner, or if you have some other
  # specific need.
  # One major limitation with this mode is that libc and libc++ cannot be
  # added in. Also, LLVM optimizations will not be done, nor dead code elimination
  LEAVE_INPUTS_RAW = int(os.environ.get('EMCC_LEAVE_INPUTS_RAW', '0'))
  
  # If emcc is running with LEAVE_INPUTS_RAW and then launches an emcc to build
  # something like the struct info, then we don't want LEAVE_INPUTS_RAW to be
  # active in that emcc subprocess.
  if LEAVE_INPUTS_RAW:
    del os.environ['EMCC_LEAVE_INPUTS_RAW']
  
  # If set to 1, we will run the autodebugger (the automatic debugging tool, see
  # tools/autodebugger).  Note that this will disable inclusion of libraries. This
  # is useful because including dlmalloc makes it hard to compare native and js
  # builds
  AUTODEBUG = os.environ.get('EMCC_AUTODEBUG')
  
  # Target options
  final = None
  
  UBSAN_SANITIZERS = {
    'alignment',
    'bool',
    'builtin',
    'bounds',
    'enum',
    'float-cast-overflow',
    'float-divide-by-zero',
    'function',
    'implicit-unsigned-integer-truncation',
    'implicit-signed-integer-truncation',
    'implicit-integer-sign-change',
    'integer-divide-by-zero',
    'nonnull-attribute',
    'null',
    'nullability-arg',
    'nullability-assign',
    'nullability-return',
    'object-size',
    'pointer-overflow',
    'return',
    'returns-nonnull-attribute',
    'shift',
    'signed-integer-overflow',
    'unreachable',
    'unsigned-integer-overflow',
    'vla-bound',
    'vptr',
    'undefined',
    'undefined-trap',
    'implicit-integer-truncation',
    'implicit-integer-arithmetic-value-change',
    'implicit-conversion',
    'integer',
    'nullability',
  }
  
  
  class Intermediate(object):
    counter = 0
  
  
  # this function uses the global 'final' variable, which contains the current
  # final output file. if a method alters final, and calls this method, then it
  # must modify final globally (i.e. it can't receive final as a param and
  # return it)
  # TODO: refactor all this, a singleton that abstracts over the final output
  #       and saving of intermediates
  def save_intermediate(name, suffix='js'):
    if not DEBUG:
      return
    name = os.path.join(shared.get_emscripten_temp_dir(), 'emcc-%d-%s.%s' % (Intermediate.counter, name, suffix))
    if isinstance(final, list):
      logger.debug('(not saving intermediate %s because deferring linking)' % name)
      return
    shutil.copyfile(final, name)
    Intermediate.counter += 1
  
  
  def save_intermediate_with_wasm(name, wasm_binary):
    if not DEBUG:
      return
    save_intermediate(name) # save the js
    name = os.path.join(shared.get_emscripten_temp_dir(), 'emcc-%d-%s.wasm' % (Intermediate.counter - 1, name))
    shutil.copyfile(wasm_binary, name)
  
  
  class TimeLogger(object):
    last = time.time()
  
    @staticmethod
    def update():
      TimeLogger.last = time.time()
  
  
  def log_time(name):
    """Log out times for emcc stages"""
    if DEBUG:
      now = time.time()
      logger.debug('emcc step "%s" took %.2f seconds', name, now - TimeLogger.last)
      TimeLogger.update()
  
  
  class EmccOptions(object):
    def __init__(self):
      self.opt_level = 0
      self.debug_level = 0
      self.shrink_level = 0
      self.requested_debug = ''
      self.profiling = False
      self.profiling_funcs = False
      self.tracing = False
      self.emit_symbol_map = False
      self.js_opts = None
      self.force_js_opts = False
      self.llvm_opts = None
      self.llvm_lto = None
      self.default_cxx_std = '-std=c++03' # Enforce a consistent C++ standard when compiling .cpp files, if user does not specify one on the cmdline.
      self.use_closure_compiler = None
      self.closure_args = []
      self.js_transform = None
      self.pre_js = '' # before all js
      self.post_js = '' # after all js
      self.preload_files = []
      self.embed_files = []
      self.exclude_files = []
      self.ignore_dynamic_linking = False
      self.shell_path = shared.path_from_root('src', 'shell.html')
      self.source_map_base = ''
      self.js_libraries = []
      self.emrun = False
      self.cpu_profiler = False
      self.thread_profiler = False
      self.memory_profiler = False
      self.save_bc = False
      self.memory_init_file = None
      self.use_preload_cache = False
      self.no_heap_copy = False
      self.use_preload_plugins = False
      self.proxy_to_worker = False
      self.default_object_extension = '.o'
      self.valid_abspaths = []
      self.separate_asm = False
      self.cfi = False
      # Specifies the line ending format to use for all generated text files.
      # Defaults to using the native EOL on each platform (\r\n on Windows, \n on
      # Linux & MacOS)
      self.output_eol = os.linesep
      self.binaryen_passes = []
      # Whether we will expand the full path of any input files to remove any
      # symlinks.
      self.expand_symlinks = True
  
  
  def use_source_map(options):
    return options.debug_level >= 4
  
  
  def will_metadce(options):
    return options.opt_level >= 3 or options.shrink_level >= 1
  
  
  class JSOptimizer(object):
    def __init__(self, target, options, js_transform_tempfiles, in_temp):
      self.queue = []
      self.extra_info = {}
      self.queue_history = []
      self.blacklist = os.environ.get('EMCC_JSOPT_BLACKLIST', '').split(',')
      self.minify_whitespace = False
      self.cleanup_shell = False
  
      self.target = target
      self.opt_level = options.opt_level
      self.debug_level = options.debug_level
      self.emit_symbol_map = options.emit_symbol_map
      self.profiling_funcs = options.profiling_funcs
      self.use_closure_compiler = options.use_closure_compiler
      self.closure_args = options.closure_args
  
      self.js_transform_tempfiles = js_transform_tempfiles
      self.in_temp = in_temp
  
    def flush(self, title='js_opts'):
      self.queue = [p for p in self.queue if p not in self.blacklist]
  
      assert not shared.Settings.WASM_BACKEND, 'JSOptimizer should not run with pure wasm output'
  
      if self.extra_info is not None and len(self.extra_info) == 0:
        self.extra_info = None
  
      if len(self.queue) and not(not shared.Settings.ASM_JS and len(self.queue) == 1 and self.queue[0] == 'last'):
        passes = self.queue[:]
  
        if DEBUG != 2 or len(passes) < 2:
          # by assumption, our input is JS, and our output is JS. If a pass is going to run in the native optimizer in C++, then we
          # must give it JSON and receive from it JSON
          chunks = []
          curr = []
          for p in passes:
            if len(curr) == 0:
              curr.append(p)
            else:
              native = js_optimizer.use_native(p, source_map=use_source_map(self))
              last_native = js_optimizer.use_native(curr[-1], source_map=use_source_map(self))
              if native == last_native:
                curr.append(p)
              else:
                curr.append('emitJSON')
                chunks.append(curr)
                curr = ['receiveJSON', p]
          if len(curr):
            chunks.append(curr)
          if len(chunks) == 1:
            self.run_passes(chunks[0], title, just_split=False, just_concat=False)
          else:
            for i, chunk in enumerate(chunks):
              self.run_passes(chunk, 'js_opts_' + str(i),
                              just_split='receiveJSON' in chunk,
                              just_concat='emitJSON' in chunk)
        else:
          # DEBUG 2, run each pass separately
          extra_info = self.extra_info
          for p in passes:
            self.queue = [p]
            self.flush(p)
            self.extra_info = extra_info # flush wipes it
            log_time('part of js opts')
        self.queue_history += self.queue
        self.queue = []
      self.extra_info = {}
  
    def run_passes(self, passes, title, just_split, just_concat):
      global final
      passes = ['asm'] + passes
      if shared.Settings.PRECISE_F32:
        passes = ['asmPreciseF32'] + passes
      if (self.emit_symbol_map or shared.Settings.CYBERDWARF) and 'minifyNames' in passes:
        passes += ['symbolMap=' + self.target + '.symbols']
      if self.profiling_funcs and 'minifyNames' in passes:
        passes += ['profilingFuncs']
      if self.minify_whitespace and 'last' in passes:
        passes += ['minifyWhitespace']
      if self.cleanup_shell and 'last' in passes:
        passes += ['cleanup']
      logger.debug('applying js optimization passes: %s', ' '.join(passes))
      final = shared.Building.js_optimizer(final, passes, use_source_map(self),
                                           self.extra_info, just_split=just_split,
                                           just_concat=just_concat,
                                           output_filename=self.in_temp(os.path.basename(final) + '.jsopted.js'),
                                           extra_closure_args=self.closure_args)
      self.js_transform_tempfiles.append(final)
      save_intermediate(title, suffix='js' if 'emitJSON' not in passes else 'json')
  
    def do_minify(self):
      """minifies the code.
  
      this is also when we do certain optimizations that must be done right before or after minification
      """
      if self.opt_level >= 2:
        if self.debug_level < 2 and not self.use_closure_compiler == 2:
          self.queue += ['minifyNames']
        if self.debug_level == 0:
          self.minify_whitespace = True
  
      if self.use_closure_compiler == 1:
        self.queue += ['closure']
      elif self.debug_level <= 2 and shared.Settings.FINALIZE_ASM_JS and not self.use_closure_compiler:
        self.cleanup_shell = True
  
  
  def embed_memfile(options):
    return (shared.Settings.SINGLE_FILE or
            (shared.Settings.MEM_INIT_METHOD == 0 and
             (not shared.Settings.MAIN_MODULE and
              not shared.Settings.SIDE_MODULE and
              not use_source_map(options))))
  
  
  def apply_settings(changes):
    """Take a list of settings in form `NAME=VALUE` and apply them to the global
    Settings object.
    """
  
    def standardize_setting_change(key, value):
      # Handle aliases in settings flags. These are settings whose name
      # has changed.
      settings_aliases = {
        'BINARYEN': 'WASM',
        'BINARYEN_MEM_MAX': 'WASM_MEM_MAX',
        # TODO: change most (all?) other BINARYEN* names to WASM*
      }
      key = settings_aliases.get(key, key)
      # boolean NO_X settings are aliases for X
      # (note that *non*-boolean setting values have special meanings,
      # and we can't just flip them, so leave them as-is to be
      # handled in a special way later)
      if key.startswith('NO_') and value in ('0', '1'):
        key = key[3:]
        value = str(1 - int(value))
      return key, value
  
    for change in changes:
      key, value = change.split('=', 1)
      key, value = standardize_setting_change(key, value)
  
      # In those settings fields that represent amount of memory, translate suffixes to multiples of 1024.
      if key in ('TOTAL_STACK', 'TOTAL_MEMORY', 'MEMORY_GROWTH_STEP', 'GL_MAX_TEMP_BUFFER_SIZE',
                 'WASM_MEM_MAX', 'DEFAULT_PTHREAD_STACK_SIZE'):
        value = str(shared.expand_byte_size_suffixes(value))
  
      if value[0] == '@':
        if key not in DEFERRED_RESPONSE_FILES:
          value = open(value[1:]).read()
      else:
        value = value.replace('\\', '\\\\')
      try:
        setattr(shared.Settings, key, parse_value(value))
      except Exception as e:
        exit_with_error('a problem occured in evaluating the content after a "-s", specifically "%s": %s', change, str(e))
  
      if shared.Settings.WASM_BACKEND and key == 'BINARYEN_TRAP_MODE':
        exit_with_error('BINARYEN_TRAP_MODE is not supported by the LLVM wasm backend')
  
      if key == 'EXPORTED_FUNCTIONS':
        # used for warnings in emscripten.py
        shared.Settings.ORIGINAL_EXPORTED_FUNCTIONS = shared.Settings.EXPORTED_FUNCTIONS[:]
  
  
  def find_output_arg(args):
    """Find and remove any -o arguments.  The final one takes precedence.
    Return the final -o target along with the remaining (non-o) arguments.
    """
    outargs = []
    specified_target = None
    use_next = False
    for arg in args:
      if use_next:
        specified_target = arg
        use_next = False
        continue
      if arg == '-o':
        use_next = True
      elif arg.startswith('-o'):
        specified_target = arg[2:]
      else:
        outargs.append(arg)
    return specified_target, outargs
  
  
  def do_emscripten(infile, memfile, js_libraries):
    # Run Emscripten
    outfile = infile + '.o.js'
    with ToolchainProfiler.profile_block('emscripten.py'):
      emscripten.run(infile, outfile, memfile, js_libraries)
  
    # Detect compilation crashes and errors
    assert os.path.exists(outfile), 'Emscripten failed to generate .js'
  
    return outfile
  
  
  #
  # Main run() function
  #
  def run(args):
    global final
    target = None
  
    # Additional compiler flags that we treat as if they were passed to us on the
    # commandline
    EMCC_CFLAGS = os.environ.get('EMCC_CFLAGS')
    if DEBUG:
      cmd = ' '.join(args)
      if EMCC_CFLAGS:
        cmd += ' + ' + EMCC_CFLAGS
      logger.warning('invocation: ' + cmd + '  (in ' + os.getcwd() + ')')
    if EMCC_CFLAGS:
      args.extend(shlex.split(EMCC_CFLAGS))
  
    # Strip args[0] (program name)
    args = args[1:]
  
    if DEBUG and LEAVE_INPUTS_RAW:
      logger.warning('leaving inputs raw')
  
    if '--emscripten-cxx' in args:
      run_via_emxx = True
      args = [x for x in args if x != '--emscripten-cxx']
    else:
      run_via_emxx = False
  
    misc_temp_files = shared.configuration.get_temp_files()
  
    # Handle some global flags
  
    # read response files very early on
    try:
      args = substitute_response_files(args)
    except IOError as e:
      exit_with_error(e)
  
    if '--help' in args:
      # Documentation for emcc and its options must be updated in:
      #    site/source/docs/tools_reference/emcc.rst
      # A prebuilt local version of the documentation is available at:
      #    site/build/text/docs/tools_reference/emcc.txt
      #    (it is read from there and printed out when --help is invoked)
      # You can also build docs locally as HTML or other formats in site/
      # An online HTML version (which may be of a different version of Emscripten)
      #    is up at http://kripken.github.io/emscripten-site/docs/tools_reference/emcc.html
  
      print('''%s
  
  ------------------------------------------------------------------
  
  emcc: supported targets: llvm bitcode, javascript, NOT elf
  (autoconf likes to see elf above to enable shared object support)
  ''' % (open(shared.path_from_root('site', 'build', 'text', 'docs', 'tools_reference', 'emcc.txt')).read()))
      return 0
  
    if '--version' in args:
      try:
        revision = run_process(['git', 'show'], stdout=PIPE, stderr=PIPE, cwd=shared.path_from_root()).stdout.splitlines()[0]
      except Exception:
        revision = '(unknown revision)'
      print('''emcc (Emscripten gcc/clang-like replacement) %s (%s)
  Copyright (C) 2014 the Emscripten authors (see AUTHORS.txt)
  This is free and open source software under the MIT license.
  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    ''' % (shared.EMSCRIPTEN_VERSION, revision))
      return 0
  
    if len(args) == 1 and args[0] == '-v': # -v with no inputs
      # autoconf likes to see 'GNU' in the output to enable shared object support
      print('emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) %s' % shared.EMSCRIPTEN_VERSION, file=sys.stderr)
      code = run_process([shared.CLANG_CC, '-v'], check=False).returncode
      shared.check_sanity(force=True)
      return code
  
    shared.check_sanity(force=DEBUG)
  
    # This check comes after check_sanity because test_sanity expects this.
    if not args:
      logger.warning('no input files')
      return 1
  
    if '-dumpmachine' in args:
      print(shared.get_llvm_target())
      return 0
  
    if '-dumpversion' in args: # gcc's doc states "Print the compiler version [...] and don't do anything else."
      print(shared.EMSCRIPTEN_VERSION)
      return 0
  
    if '--cflags' in args:
      # fake running the command, to see the full args we pass to clang
      debug_env = os.environ.copy()
      args = [x for x in args if x != '--cflags']
      with misc_temp_files.get_file(suffix='.o') as temp_target:
        input_file = 'hello_world.c'
        cmd = [shared.PYTHON, sys.argv[0], shared.path_from_root('tests', input_file), '-v', '-c', '-o', temp_target] + args
        proc = run_process(cmd, stderr=PIPE, env=debug_env, check=False)
        if proc.returncode != 0:
          print(proc.stderr)
          exit_with_error('error getting cflags')
        lines = [x for x in proc.stderr.splitlines() if shared.CLANG_CC in x and input_file in x]
        parts = shlex.split(lines[0].replace('\\', '\\\\'))
        parts = [x for x in parts if x not in ['-c', '-o', '-v', '-emit-llvm'] and input_file not in x and temp_target not in x]
        print(' '.join(shared.Building.doublequote_spaces(parts[1:])))
      return 0
  
    # Default to using C++ even when run as `emcc`.
    # This means that emcc will act as a C++ linker when no source files are
    # specified.  However, when a C source is specified we do default to C.
    # This differs to clang and gcc where the default is always C unless run as
    # clang++/g++.
    use_cxx = True
  
    def get_language_mode(args):
      return_next = False
      for item in args:
        if return_next:
          return item
        if item == '-x':
          return_next = True
          continue
        if item.startswith('-x'):
          return item[2:]
      return None
  
    def has_c_source(args):
      for a in args:
        if a[0] != '-' and a.endswith(C_ENDINGS + OBJC_ENDINGS):
          return True
      return False
  
    language_mode = get_language_mode(args)
    has_fixed_language_mode = language_mode is not None
    if language_mode == 'c':
      use_cxx = False
  
    if not has_fixed_language_mode:
      if not run_via_emxx and has_c_source(args):
        use_cxx = False
  
    def is_minus_s_for_emcc(args, i):
      # -s OPT=VALUE or -s OPT are interpreted as emscripten flags.
      # -s by itself is a linker option (alias for --strip-all)
      assert args[i] == '-s'
      if len(args) > i + 1:
        arg = args[i + 1]
        if arg.split('=')[0].isupper():
          return True
  
      logger.debug('treating -s as linker option and not as -s OPT=VALUE for js compilation')
      return False
  
    # If this is a configure-type thing, do not compile to JavaScript, instead use clang
    # to compile to a native binary (using our headers, so things make sense later)
    CONFIGURE_CONFIG = (os.environ.get('EMMAKEN_JUST_CONFIGURE') or 'conftest.c' in args) and not os.environ.get('EMMAKEN_JUST_CONFIGURE_RECURSE')
    CMAKE_CONFIG = 'CMakeFiles/cmTryCompileExec.dir' in ' '.join(args)# or 'CMakeCCompilerId' in ' '.join(args)
    if CONFIGURE_CONFIG or CMAKE_CONFIG:
      # XXX use this to debug configure stuff. ./configure's generally hide our
      # normal output including stderr so we write to a file
      debug_configure = 0
  
      # Whether we fake configure tests using clang - the local, native compiler -
      # or not. if not we generate JS and use node with a shebang
      # Neither approach is perfect, you can try both, but may need to edit
      # configure scripts in some cases
      # By default we configure in js, which can break on local filesystem access,
      # etc., but is otherwise accurate so we
      # disable this if we think we have to. A value of '2' here will force JS
      # checks in all cases. In summary:
      # 0 - use native compilation for configure checks
      # 1 - use js when we think it will work
      # 2 - always use js for configure checks
      use_js = int(os.environ.get('EMCONFIGURE_JS', '2'))
  
      if debug_configure:
        tempout = '/tmp/emscripten_temp/out'
        if not os.path.exists(tempout):
          open(tempout, 'w').write('//\n')
  
      src = None
      for arg in args:
        if arg.endswith(SOURCE_ENDINGS):
          try:
            src = open(arg).read()
            if debug_configure:
              open(tempout, 'a').write('============= ' + arg + '\n' + src + '\n=============\n\n')
          except IOError:
            pass
        elif arg.endswith('.s'):
          if debug_configure:
            open(tempout, 'a').write('(compiling .s assembly, must use clang\n')
          if use_js == 1:
            use_js = 0
        elif arg == '-E' or arg == '-M' or arg == '-MM':
          if use_js == 1:
            use_js = 0
  
      if src:
        if 'fopen' in src and '"w"' in src:
          if use_js == 1:
            use_js = 0 # we cannot write to files from js!
          if debug_configure:
            open(tempout, 'a').write('Forcing clang since uses fopen to write\n')
  
      # if CONFIGURE_CC is defined, use that. let's you use local gcc etc. if you need that
      compiler = os.environ.get('CONFIGURE_CC')
      if not compiler:
        compiler = shared.EMXX if use_js else shared.CLANG_CPP
      if 'CXXCompiler' not in ' '.join(args) and not use_cxx:
        compiler = shared.to_cc(compiler)
  
      def filter_emscripten_options(argv):
        skip_next = False
        for idx, arg in enumerate(argv):
          if skip_next:
            skip_next = False
            continue
          if not use_js and arg == '-s' and is_minus_s_for_emcc(argv, idx):
            # skip -s X=Y if not using js for configure
            skip_next = True
            continue
          if use_js or arg != '--tracing':
            yield arg
  
      if compiler in (shared.EMCC, shared.EMXX):
        compiler = [shared.PYTHON, compiler]
      else:
        compiler = [compiler]
      cmd = compiler + list(filter_emscripten_options(args))
      if not use_js:
        cmd += shared.emsdk_cflags() + ['-D__EMSCRIPTEN__']
        # The preprocessor define EMSCRIPTEN is deprecated. Don't pass it to code
        # in strict mode. Code should use the define __EMSCRIPTEN__ instead.
        if not shared.Settings.STRICT:
          cmd += ['-DEMSCRIPTEN']
      if use_js:
        # configure tests want a more shell-like style, where we emit return codes on exit()
        cmd += ['-s', 'NO_EXIT_RUNTIME=0']
        # use node.js raw filesystem access, to behave just like a native executable
        cmd += ['-s', 'NODERAWFS=1']
  
      logger.debug('just configuring: ' + ' '.join(cmd))
      if debug_configure:
        open(tempout, 'a').write('emcc, just configuring: ' + ' '.join(cmd) + '\n\n')
  
      if not use_js:
        return run_process(cmd, check=False).returncode
  
      only_object = '-c' in cmd
      for i in reversed(range(len(cmd) - 1)): # Last -o directive should take precedence, if multiple are specified
        if cmd[i] == '-o':
          if not only_object:
            cmd[i + 1] += '.js'
          target = cmd[i + 1]
          break
      if not target:
        target = 'a.out.js'
      os.environ['EMMAKEN_JUST_CONFIGURE_RECURSE'] = '1'
      ret = run_process(cmd, check=False).returncode
      os.environ['EMMAKEN_JUST_CONFIGURE_RECURSE'] = ''
      if not os.path.exists(target):
        # note that emcc -c will cause target to have the wrong value here;
        # but then, we don't care about bitcode outputs anyhow, below, so
        # skipping returning early is fine
        return ret
      if target.endswith('.js'):
        shutil.copyfile(target, unsuffixed(target))
        target = unsuffixed(target)
      if not target.endswith(OBJECT_FILE_ENDINGS):
        src = open(target).read()
        full_node = ' '.join(shared.NODE_JS)
        if os.path.sep not in full_node:
          full_node = '/usr/bin/' + full_node # TODO: use whereis etc. And how about non-*NIX?
        open(target, 'w').write('#!' + full_node + '\n' + src) # add shebang
        try:
          os.chmod(target, stat.S_IMODE(os.stat(target).st_mode) | stat.S_IXUSR) # make executable
        except OSError:
          pass # can fail if e.g. writing the executable to /dev/null
      return ret
  
    CXX = os.environ.get('EMMAKEN_COMPILER', shared.CLANG_CPP)
    CC = shared.to_cc(CXX)
  
    EMMAKEN_CFLAGS = os.environ.get('EMMAKEN_CFLAGS')
    if EMMAKEN_CFLAGS:
      args += shlex.split(EMMAKEN_CFLAGS)
  
    # ---------------- Utilities ---------------
  
    def suffix(name):
      """Return the file extension"""
      return os.path.splitext(name)[1]
  
    seen_names = {}
  
    def uniquename(name):
      if name not in seen_names:
        seen_names[name] = str(len(seen_names))
      return unsuffixed(name) + '_' + seen_names[name] + suffix(name)
  
    # ---------------- End configs -------------
  
    # Check if a target is specified on the command line
    specified_target, args = find_output_arg(args)
  
    # specified_target is the user-specified one, target is what we will generate
    if specified_target:
      target = specified_target
      # check for the existence of the output directory now, to avoid having
      # to do so repeatedly when each of the various output files (.mem, .wasm,
      # etc) are written. This gives a more useful error message than the
      # IOError and python backtrace that users would otherwise see.
      dirname = os.path.dirname(target)
      if dirname and not os.path.isdir(dirname):
        exit_with_error("specified output file (%s) is in a directory that does not exist" % target)
    else:
      target = 'a.out.js'
  
    shared.Settings.TARGET_BASENAME = target_basename = unsuffixed_basename(target)
  
    final_suffix = suffix(target)
  
    temp_dir = shared.get_emscripten_temp_dir()
  
    def in_temp(name):
      return os.path.join(temp_dir, os.path.basename(name))
  
    def get_file_suffix(filename):
      """Parses the essential suffix of a filename, discarding Unix-style version
      numbers in the name. For example for 'libz.so.1.2.8' returns '.so'"""
      if filename in SPECIAL_ENDINGLESS_FILENAMES:
        return filename
      while filename:
        filename, suffix = os.path.splitext(filename)
        if not suffix[1:].isdigit():
          return suffix
      return ''
  
    def optimizing(opts):
      return '-O0' not in opts
  
    with ToolchainProfiler.profile_block('parse arguments and setup'):
      ## Parse args
  
      newargs = list(args)
  
      # Scan and strip emscripten specific cmdline warning flags.
      # This needs to run before other cmdline flags have been parsed, so that
      # warnings are properly printed during arg parse.
      newargs = shared.WarningManager.capture_warnings(newargs)
  
      for i in range(len(newargs)):
        if newargs[i] in ('-l', '-L', '-I'):
          # Scan for individual -l/-L/-I arguments and concatenate the next arg on
          # if there is no suffix
          newargs[i] += newargs[i + 1]
          newargs[i + 1] = ''
  
      options, settings_changes, newargs = parse_args(newargs)
  
      if use_cxx:
        clang_compiler = CXX
        # If user did not specify a default -std for C++ code, specify the emscripten default.
        if options.default_cxx_std:
          newargs += [options.default_cxx_std]
      else:
        # Compiling C code with .c files, don't enforce a default C++ std.
        clang_compiler = CC
  
      if '-print-search-dirs' in newargs:
        return run_process([clang_compiler, '-print-search-dirs'], check=False).returncode
  
      if options.emrun:
        options.pre_js += open(shared.path_from_root('src', 'emrun_prejs.js')).read() + '\n'
        options.post_js += open(shared.path_from_root('src', 'emrun_postjs.js')).read() + '\n'
        # emrun mode waits on program exit
        shared.Settings.EXIT_RUNTIME = 1
  
      if options.cpu_profiler:
        options.post_js += open(shared.path_from_root('src', 'cpuprofiler.js')).read() + '\n'
  
      if options.memory_profiler:
        shared.Settings.MEMORYPROFILER = 1
  
      if options.thread_profiler:
        options.post_js += open(shared.path_from_root('src', 'threadprofiler.js')).read() + '\n'
  
      if options.js_opts is None:
        options.js_opts = options.opt_level >= 2
  
      if options.llvm_opts is None:
        options.llvm_opts = LLVM_OPT_LEVEL[options.opt_level]
      elif type(options.llvm_opts) == int:
        options.llvm_opts = ['-O%d' % options.llvm_opts]
  
      if options.memory_init_file is None:
        options.memory_init_file = options.opt_level >= 2
  
      # TODO: support source maps with js_transform
      if options.js_transform and use_source_map(options):
        logger.warning('disabling source maps because a js transform is being done')
        options.debug_level = 3
  
      if DEBUG:
        start_time = time.time() # done after parsing arguments, which might affect debug state
  
      for i in range(len(newargs)):
        if newargs[i] == '-s':
          if is_minus_s_for_emcc(newargs, i):
            key = newargs[i + 1]
            # If not = is specified default to 1
            if '=' not in key:
              key += '=1'
            settings_changes.append(key)
            newargs[i] = newargs[i + 1] = ''
            if key == 'WASM_BACKEND=1':
              exit_with_error('do not set -s WASM_BACKEND, instead set EMCC_WASM_BACKEND=1 in the environment')
      newargs = [arg for arg in newargs if arg]
  
      settings_key_changes = set()
      for s in settings_changes:
        key, value = s.split('=', 1)
        settings_key_changes.add(key)
  
      # Find input files
  
      # These three arrays are used to store arguments of different types for
      # type-specific processing. In order to shuffle the arguments back together
      # after processing, all of these arrays hold tuples (original_index, value).
      # Note that the index part of the tuple can have a fractional part for input
      # arguments that expand into multiple processed arguments, as in -Wl,-f1,-f2.
      input_files = []
      libs = []
      link_flags = []
  
      # All of the above arg lists entries contain indexes into the full argument
      # list. In order to add extra implicit args (embind.cc, etc) below, we keep a
      # counter for the next index that should be used.
      next_arg_index = len(newargs)
  
      has_source_inputs = False
      has_header_inputs = False
      lib_dirs = []
  
      has_dash_c = '-c' in newargs
      has_dash_S = '-S' in newargs
      executable_endings = JS_CONTAINING_ENDINGS + ('.wasm',)
      compile_only = has_dash_c or has_dash_S
  
      link_to_object = final_suffix not in executable_endings
  
      def add_link_flag(i, f):
        # Filter out libraries that musl includes in libc itself, or which we
        # otherwise provide implicitly.
        if f in ('-lm', '-lrt', '-ldl', '-lpthread'):
          return
        if f.startswith('-l'):
          libs.append((i, f[2:]))
        if f.startswith('-L'):
          lib_dirs.append(f[2:])
  
        link_flags.append((i, f))
  
      # find input files this a simple heuristic. we should really analyze
      # based on a full understanding of gcc params, right now we just assume that
      # what is left contains no more |-x OPT| things
      for i in range(len(newargs)):
        arg = newargs[i]
        if i > 0:
          prev = newargs[i - 1]
          if prev in ('-MT', '-MF', '-MQ', '-D', '-U', '-o', '-x',
                      '-Xpreprocessor', '-include', '-imacros', '-idirafter',
                      '-iprefix', '-iwithprefix', '-iwithprefixbefore',
                      '-isysroot', '-imultilib', '-A', '-isystem', '-iquote',
                      '-install_name', '-compatibility_version',
                      '-current_version', '-I', '-L', '-include-pch'):
            continue # ignore this gcc-style argument
  
        if options.expand_symlinks and os.path.islink(arg) and get_file_suffix(os.path.realpath(arg)) in SOURCE_ENDINGS + OBJECT_FILE_ENDINGS + DYNAMICLIB_ENDINGS + ASSEMBLY_ENDINGS + HEADER_ENDINGS:
          arg = os.path.realpath(arg)
  
        if not arg.startswith('-'):
          if not os.path.exists(arg):
            exit_with_error('%s: No such file or directory ("%s" was expected to be an input file, based on the commandline arguments provided)', arg, arg)
  
          file_suffix = get_file_suffix(arg)
          if file_suffix in SOURCE_ENDINGS + OBJECT_FILE_ENDINGS + DYNAMICLIB_ENDINGS + ASSEMBLY_ENDINGS + HEADER_ENDINGS or shared.Building.is_ar(arg): # we already removed -o <target>, so all these should be inputs
            newargs[i] = ''
            if file_suffix.endswith(SOURCE_ENDINGS):
              input_files.append((i, arg))
              has_source_inputs = True
            elif file_suffix.endswith(HEADER_ENDINGS):
              input_files.append((i, arg))
              has_header_inputs = True
            elif file_suffix.endswith(ASSEMBLY_ENDINGS) or shared.Building.is_bitcode(arg) or shared.Building.is_ar(arg):
              input_files.append((i, arg))
            elif shared.Building.is_wasm(arg):
              if not shared.Settings.WASM_BACKEND:
                exit_with_error('fastcomp is not compatible with wasm object files:' + arg)
              input_files.append((i, arg))
            elif file_suffix.endswith(STATICLIB_ENDINGS + DYNAMICLIB_ENDINGS):
              # if it's not, and it's a library, just add it to libs to find later
              libname = unsuffixed_basename(arg)
              for prefix in LIB_PREFIXES:
                if not prefix:
                  continue
                if libname.startswith(prefix):
                  libname = libname[len(prefix):]
                  break
              libs.append((i, libname))
              newargs[i] = ''
            else:
              logger.warning(arg + ' is not a valid input file')
          elif file_suffix.endswith(STATICLIB_ENDINGS):
            if not shared.Building.is_ar(arg):
              if shared.Building.is_bitcode(arg):
                message = arg + ': File has a suffix of a static library ' + str(STATICLIB_ENDINGS) + ', but instead is an LLVM bitcode file! When linking LLVM bitcode files, use one of the suffixes ' + str(OBJECT_FILE_ENDINGS)
              else:
                message = arg + ': Unknown format, not a static library!'
              exit_with_error(message)
          else:
            if has_fixed_language_mode:
              newargs[i] = ''
              input_files.append((i, arg))
              has_source_inputs = True
            else:
              exit_with_error(arg + ": Input file has an unknown suffix, don't know what to do with it!")
        elif arg.startswith('-L'):
          add_link_flag(i, arg)
          newargs[i] = ''
        elif arg.startswith('-l'):
          add_link_flag(i, arg)
          newargs[i] = ''
        elif arg.startswith('-Wl,'):
          # Multiple comma separated link flags can be specified. Create fake
          # fractional indices for these: -Wl,a,b,c,d at index 4 becomes:
          # (4, a), (4.25, b), (4.5, c), (4.75, d)
          link_flags_to_add = arg.split(',')[1:]
          for flag_index, flag in enumerate(link_flags_to_add):
            add_link_flag(i + float(flag_index) / len(link_flags_to_add), flag)
          newargs[i] = ''
        elif arg == '-s':
          # -s and some other compiler flags are normally passed onto the linker
          # TODO(sbc): Pass this and other flags through when using lld
          # link_flags.append((i, arg))
          newargs[i] = ''
  
      newargs = [a for a in newargs if a]
  
      if '-fno-rtti' in newargs:
        shared.Settings.USE_RTTI = 0
  
      if has_dash_c or has_dash_S:
        assert has_source_inputs or has_header_inputs, 'Must have source code or header inputs to use -c or -S'
        if has_dash_c:
          if '-emit-llvm' in newargs:
            final_suffix = '.bc'
          else:
            final_suffix = options.default_object_extension
        elif has_dash_S:
          if '-emit-llvm' in newargs:
            final_suffix = '.ll'
          else:
            final_suffix = '.s'
        target = target_basename + final_suffix
  
        if len(input_files) > 1 and specified_target:
          exit_with_error('cannot specify -o with -c/-S and multiple source files')
  
      if '-E' in newargs:
        final_suffix = '.eout' # not bitcode, not js; but just result from preprocessing stage of the input file
      if '-M' in newargs or '-MM' in newargs:
        final_suffix = '.mout' # not bitcode, not js; but just dependency rule of the input file
  
      # target is now finalized, can finalize other _target s
      if final_suffix == '.mjs':
        shared.Settings.EXPORT_ES6 = 1
        shared.Settings.MODULARIZE = 1
        js_target = target
      else:
        js_target = unsuffixed(target) + '.js'
  
      asm_target = unsuffixed(js_target) + '.asm.js' # might not be used, but if it is, this is the name
      wasm_text_target = asm_target.replace('.asm.js', '.wast') # ditto, might not be used
      wasm_binary_target = asm_target.replace('.asm.js', '.wasm') # ditto, might not be used
      wasm_source_map_target = wasm_binary_target + '.map'
  
      if final_suffix == '.html' and not options.separate_asm and 'PRECISE_F32=2' in settings_changes:
        options.separate_asm = True
        logger.warning('forcing separate asm output (--separate-asm), because -s PRECISE_F32=2 was passed.')
      if options.separate_asm:
        shared.Settings.SEPARATE_ASM = shared.JS.get_subresource_location(asm_target)
  
      # Libraries are searched before settings_changes are applied, so apply the
      # value for STRICT from command line already now.
  
      def get_last_setting_change(setting):
        return ([None] + [x for x in settings_changes if x.startswith(setting + '=')])[-1]
  
      strict_cmdline = get_last_setting_change('STRICT')
      if strict_cmdline:
        shared.Settings.STRICT = int(strict_cmdline.split('=', 1)[1])
  
      if options.separate_asm and final_suffix != '.html':
        shared.WarningManager.warn('SEPARATE_ASM')
  
      # Apply optimization level settings
      shared.Settings.apply_opt_level(opt_level=options.opt_level, shrink_level=options.shrink_level, noisy=True)
  
      # For users that opt out of WARN_ON_UNDEFINED_SYMBOLS we assume they also
      # want to opt out of ERROR_ON_UNDEFINED_SYMBOLS.
      if 'WARN_ON_UNDEFINED_SYMBOLS=0' in settings_changes:
        shared.Settings.ERROR_ON_UNDEFINED_SYMBOLS = 0
  
      # Set ASM_JS default here so that we can override it from the command line.
      shared.Settings.ASM_JS = 1 if options.opt_level > 0 else 2
  
      # Apply -s settings in newargs here (after optimization levels, so they can override them)
      apply_settings(settings_changes)
  
      shared.verify_settings()
  
      using_lld = shared.Settings.WASM_BACKEND and not (link_to_object and not shared.Settings.WASM_OBJECT_FILES)
  
      def filter_out_dynamic_libs(inputs):
        # If not compiling to JS, then we are compiling to an intermediate bitcode
        # objects or library, so ignore dynamic linking, since multiple dynamic
        # linkings can interfere with each other
        if get_file_suffix(target) not in JS_CONTAINING_ENDINGS or options.ignore_dynamic_linking:
          def check(input_file):
            if get_file_suffix(input_file) in DYNAMICLIB_ENDINGS:
              if not options.ignore_dynamic_linking:
                logger.warning('ignoring dynamic library %s because not compiling to JS or HTML, remember to link it when compiling to JS or HTML at the end', os.path.basename(input_file))
              return False
            else:
              return True
          return [f for f in inputs if check(f[1])]
        return inputs
  
      input_files = filter_out_dynamic_libs(input_files)
  
      if len(input_files) == 0:
        exit_with_error('no input files\nnote that input files without a known suffix are ignored, make sure your input files end with one of: ' + str(SOURCE_ENDINGS + OBJECT_FILE_ENDINGS + DYNAMICLIB_ENDINGS + STATICLIB_ENDINGS + ASSEMBLY_ENDINGS + HEADER_ENDINGS))
  
      # Note the exports the user requested
      shared.Building.user_requested_exports = shared.Settings.EXPORTED_FUNCTIONS[:]
  
      # -s ASSERTIONS=1 implies the heaviest stack overflow check mode. Set the implication here explicitly to avoid having to
      # do preprocessor "#if defined(ASSERTIONS) || defined(STACK_OVERFLOW_CHECK)" in .js files, which is not supported.
      if shared.Settings.ASSERTIONS:
        shared.Settings.STACK_OVERFLOW_CHECK = 2
  
      if shared.Settings.WASM_OBJECT_FILES and not shared.Settings.WASM_BACKEND:
        if 'WASM_OBJECT_FILES=1' in settings_changes:
          exit_with_error('WASM_OBJECT_FILES can only be used with wasm backend')
        shared.Settings.WASM_OBJECT_FILES = 0
  
      if shared.Settings.STRICT:
        shared.Settings.DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR = 1
        shared.Settings.STRICT_JS = 1
        shared.Settings.AUTO_JS_LIBRARIES = 0
  
      if AUTODEBUG:
        shared.Settings.AUTODEBUG = 1
  
      # Use settings
  
      if options.debug_level > 1 and options.use_closure_compiler:
        logger.warning('disabling closure because debug info was requested')
        options.use_closure_compiler = False
  
      if shared.Settings.EMTERPRETIFY_FILE and shared.Settings.SINGLE_FILE:
        exit_with_error('cannot have both EMTERPRETIFY_FILE and SINGLE_FILE enabled at the same time')
  
      if options.use_closure_compiler and not shared.Settings.DYNAMIC_EXECUTION:
        exit_with_error('cannot have both NO_DYNAMIC_EXECUTION and closure compiler enabled at the same time')
  
      if options.emrun:
        if shared.Settings.MINIMAL_RUNTIME:
          exit_with_error('--emrun is not compatible with -s MINIMAL_RUNTIME=1')
        shared.Settings.EXPORTED_RUNTIME_METHODS.append('addOnExit')
  
      if options.use_closure_compiler:
        shared.Settings.USE_CLOSURE_COMPILER = options.use_closure_compiler
        if not shared.check_closure_compiler():
          exit_with_error('fatal: closure compiler is not configured correctly')
        if options.use_closure_compiler == 2 and shared.Settings.ASM_JS == 1:
          shared.WarningManager.warn('ALMOST_ASM', 'not all asm.js optimizations are possible with --closure 2, disabling those - your code will be run more slowly')
          shared.Settings.ASM_JS = 2
  
      if shared.Settings.MAIN_MODULE:
        assert not shared.Settings.SIDE_MODULE
        if shared.Settings.MAIN_MODULE != 2:
          shared.Settings.INCLUDE_FULL_LIBRARY = 1
      elif shared.Settings.SIDE_MODULE:
        assert not shared.Settings.MAIN_MODULE
        options.memory_init_file = False # memory init file is not supported with asm.js side modules, must be executable synchronously (for dlopen)
  
      if shared.Settings.MAIN_MODULE or shared.Settings.SIDE_MODULE:
        assert shared.Settings.ASM_JS, 'module linking requires asm.js output (-s ASM_JS=1)'
        if shared.Settings.MAIN_MODULE != 2 and shared.Settings.SIDE_MODULE != 2:
          shared.Settings.LINKABLE = 1
        shared.Settings.RELOCATABLE = 1
        assert not options.use_closure_compiler, 'cannot use closure compiler on shared modules'
        # shared modules need memory utilities to allocate their memory
        shared.Settings.EXPORTED_RUNTIME_METHODS += [
          'allocate',
          'getMemory',
        ]
  
      if shared.Settings.RELOCATABLE:
        shared.Settings.ALLOW_TABLE_GROWTH = 1
  
      # Reconfigure the cache now that settings have been applied. Some settings
      # such as WASM_OBJECT_FILES and SIDE_MODULE/MAIN_MODULE effect which cache
      # directory we use.
      shared.reconfigure_cache()
  
      if not compile_only:
        ldflags = shared.emsdk_ldflags(newargs)
        for f in ldflags:
          newargs.append(f)
          add_link_flag(len(newargs), f)
  
      if not shared.Settings.STRICT:
        # The preprocessor define EMSCRIPTEN is deprecated. Don't pass it to code
        # in strict mode. Code should use the define __EMSCRIPTEN__ instead.
        newargs += ['-DEMSCRIPTEN']
  
      newargs = shared.COMPILER_OPTS + shared.get_cflags(newargs) + newargs
  
      def is_supported_link_flag(f):
        if f in SUPPORTED_LINKER_FLAGS:
          return True
        if using_lld:
          # Add flags here to allow -Wl, options to be passed all the way through
          # to the linker.
          valid_prefixs = ('-l', '-L', '--trace-symbol', '--trace')
          if any(f.startswith(prefix) for prefix in valid_prefixs):
            return True
        else:
          # Silently ignore -l/-L flags when not using lld.  If using lld allow
          # them to pass through the linker
          if f.startswith('-l') or f.startswith('-L'):
            return False
        logger.warning('ignoring unsupported linker flag: `%s`', f)
        return False
  
      link_flags = [f for f in link_flags if is_supported_link_flag(f[1])]
  
      if shared.Settings.USE_PTHREADS:
        # These runtime methods are called from worker.js
        shared.Settings.EXPORTED_RUNTIME_METHODS += ['establishStackSpace', 'dynCall_ii']
  
      if shared.Settings.MODULARIZE_INSTANCE:
        shared.Settings.MODULARIZE = 1
  
      if shared.Settings.MODULARIZE:
        assert not options.proxy_to_worker, '-s MODULARIZE=1 and -s MODULARIZE_INSTANCE=1 are not compatible with --proxy-to-worker (if you want to run in a worker with -s MODULARIZE=1, you likely want to do the worker side setup manually)'
        # MODULARIZE's .then() method uses onRuntimeInitialized currently, so make sure
        # it is expected to be used.
        shared.Settings.INCOMING_MODULE_JS_API += ['onRuntimeInitialized']
  
      if shared.Settings.EMULATE_FUNCTION_POINTER_CASTS:
        shared.Settings.ALIASING_FUNCTION_POINTERS = 0
  
      if shared.Settings.LEGACY_VM_SUPPORT:
        # legacy vms don't have wasm
        assert not shared.Settings.WASM or shared.Settings.WASM2JS, 'LEGACY_VM_SUPPORT is only supported for asm.js, and not wasm. Build with -s WASM=0'
        shared.Settings.POLYFILL_OLD_MATH_FUNCTIONS = 1
        shared.Settings.WORKAROUND_IOS_9_RIGHT_SHIFT_BUG = 1
        shared.Settings.WORKAROUND_OLD_WEBGL_UNIFORM_UPLOAD_IGNORED_OFFSET_BUG = 1
  
      # Silently drop any individual backwards compatibility emulation flags that are known never to occur on browsers that support WebAssembly.
      if shared.Settings.WASM and not shared.Settings.WASM2JS:
        shared.Settings.POLYFILL_OLD_MATH_FUNCTIONS = 0
        shared.Settings.WORKAROUND_IOS_9_RIGHT_SHIFT_BUG = 0
        shared.Settings.WORKAROUND_OLD_WEBGL_UNIFORM_UPLOAD_IGNORED_OFFSET_BUG = 0
  
      if shared.Settings.STB_IMAGE and final_suffix in JS_CONTAINING_ENDINGS:
        input_files.append((next_arg_index, shared.path_from_root('third_party', 'stb_image.c')))
        next_arg_index += 1
        shared.Settings.EXPORTED_FUNCTIONS += ['_stbi_load', '_stbi_load_from_memory', '_stbi_image_free']
        # stb_image 2.x need to have STB_IMAGE_IMPLEMENTATION defined to include the implementation when compiling
        newargs.append('-DSTB_IMAGE_IMPLEMENTATION')
  
      forced_stdlibs = []
  
      if shared.Settings.ASMFS and final_suffix in JS_CONTAINING_ENDINGS:
        forced_stdlibs.append('libasmfs')
        newargs.append('-D__EMSCRIPTEN_ASMFS__=1')
        next_arg_index += 1
        shared.Settings.FILESYSTEM = 0
        shared.Settings.SYSCALLS_REQUIRE_FILESYSTEM = 0
        shared.Settings.FETCH = 1
        options.js_libraries.append(shared.path_from_root('src', 'library_asmfs.js'))
  
      if shared.Settings.FETCH and final_suffix in JS_CONTAINING_ENDINGS:
        forced_stdlibs.append('libfetch')
        next_arg_index += 1
        options.js_libraries.append(shared.path_from_root('src', 'library_fetch.js'))
        if shared.Settings.USE_PTHREADS:
          shared.Settings.FETCH_WORKER_FILE = unsuffixed(os.path.basename(target)) + '.fetch.js'
  
      if not shared.Settings.USE_PTHREADS or not shared.Settings.FETCH:
        shared.Settings.USE_FETCH_WORKER = 0
  
      # In asm.js+pthreads we can use a fetch worker, which is made from the main
      # asm.js code. That lets us do sync operations by blocking on the worker etc.
      # In the wasm backend we don't have a fetch worker implemented yet, however,
      # we can still do basic synchronous fetches in the same places: if we can
      # block on another thread then we aren't the main thread, and if we aren't
      # the main thread then synchronous xhrs are legitimate.
      if shared.Settings.FETCH and shared.Settings.WASM_BACKEND:
        shared.Settings.USE_FETCH_WORKER = 0
  
      if shared.Settings.DEMANGLE_SUPPORT:
        shared.Settings.EXPORTED_FUNCTIONS += ['___cxa_demangle']
        forced_stdlibs.append('libc++abi')
  
      if shared.Settings.EMBIND:
        forced_stdlibs.append('libembind')
  
      if not shared.Settings.MINIMAL_RUNTIME:
        # Always need malloc and free to be kept alive and exported, for internal use and other modules
        shared.Settings.EXPORTED_FUNCTIONS += ['_malloc', '_free']
        if shared.Settings.WASM_BACKEND:
          # setjmp/longjmp and exception handling JS code depends on this so we
          # include it by default.  Should be eliminated by meta-DCE if unused.
          shared.Settings.EXPORTED_FUNCTIONS += ['_setThrew']
  
      if shared.Settings.RELOCATABLE and not shared.Settings.DYNAMIC_EXECUTION:
        exit_with_error('cannot have both DYNAMIC_EXECUTION=0 and RELOCATABLE enabled at the same time, since RELOCATABLE needs to eval()')
  
      if shared.Settings.SIDE_MODULE and shared.Settings.GLOBAL_BASE != -1:
        exit_with_error('Cannot set GLOBAL_BASE when building SIDE_MODULE')
  
      if shared.Settings.RELOCATABLE:
        if 'EMULATED_FUNCTION_POINTERS' not in settings_key_changes and not shared.Settings.WASM_BACKEND:
          shared.Settings.EMULATED_FUNCTION_POINTERS = 2 # by default, use optimized function pointer emulation
        shared.Settings.ERROR_ON_UNDEFINED_SYMBOLS = 0
        shared.Settings.WARN_ON_UNDEFINED_SYMBOLS = 0
  
      if shared.Settings.ASYNCIFY:
        if not shared.Settings.WASM_BACKEND:
          exit_with_error('ASYNCIFY has been removed from fastcomp. There is a new implementation which can be used in the upstream wasm backend.')
  
      if shared.Settings.EMTERPRETIFY:
        shared.Settings.FINALIZE_ASM_JS = 0
        shared.Settings.SIMPLIFY_IFS = 0 # this is just harmful for emterpreting
        shared.Settings.EXPORTED_FUNCTIONS += ['emterpret']
        if not options.js_opts:
          logger.debug('enabling js opts for EMTERPRETIFY')
          options.js_opts = True
        options.force_js_opts = True
        if options.use_closure_compiler == 2:
           exit_with_error('EMTERPRETIFY requires valid asm.js, and is incompatible with closure 2 which disables that')
        assert not use_source_map(options), 'EMTERPRETIFY is not compatible with source maps (maps are not useful in emterpreted code, and splitting out non-emterpreted source maps is not yet implemented)'
  
      if shared.Settings.DISABLE_EXCEPTION_THROWING and not shared.Settings.DISABLE_EXCEPTION_CATCHING:
        exit_with_error("DISABLE_EXCEPTION_THROWING was set (probably from -fno-exceptions) but is not compatible with enabling exception catching (DISABLE_EXCEPTION_CATCHING=0). If you don't want exceptions, set DISABLE_EXCEPTION_CATCHING to 1; if you do want exceptions, don't link with -fno-exceptions")
  
      if shared.Settings.DEAD_FUNCTIONS:
        if not options.js_opts:
          logger.debug('enabling js opts for DEAD_FUNCTIONS')
          options.js_opts = True
        options.force_js_opts = True
  
      if options.proxy_to_worker:
        shared.Settings.PROXY_TO_WORKER = 1
  
      if options.use_preload_plugins or len(options.preload_files) or len(options.embed_files):
        if shared.Settings.NODERAWFS:
          exit_with_error('--preload-file and --embed-file cannot be used with NODERAWFS which disables virtual filesystem')
        # if we include any files, or intend to use preload plugins, then we definitely need filesystem support
        shared.Settings.FORCE_FILESYSTEM = 1
  
      if options.proxy_to_worker or options.use_preload_plugins:
        shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$Browser']
  
      if not shared.Settings.MINIMAL_RUNTIME:
        # In non-MINIMAL_RUNTIME, the core runtime depends on these functions to be present. (In MINIMAL_RUNTIME, they are
        # no longer always bundled in)
        shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$demangle', '$demangleAll', '$jsStackTrace', '$stackTrace']
  
      if shared.Settings.FILESYSTEM:
        if shared.Settings.SUPPORT_ERRNO:
          shared.Settings.EXPORTED_FUNCTIONS += ['___errno_location'] # so FS can report errno back to C
        # to flush streams on FS exit, we need to be able to call fflush
        # we only include it if the runtime is exitable, or when ASSERTIONS
        # (ASSERTIONS will check that streams do not need to be flushed,
        # helping people see when they should have disabled NO_EXIT_RUNTIME)
        if shared.Settings.EXIT_RUNTIME or shared.Settings.ASSERTIONS:
          shared.Settings.EXPORTED_FUNCTIONS += ['_fflush']
  
      if shared.Settings.GLOBAL_BASE < 0:
        # default if nothing else sets it
        if shared.Settings.WASM:
          # a higher global base is useful for optimizing load/store offsets, as it
          # enables the --post-emscripten pass
          shared.Settings.GLOBAL_BASE = 1024
        else:
          shared.Settings.GLOBAL_BASE = 8
  
      if shared.Settings.USE_PTHREADS:
        if shared.Settings.USE_PTHREADS == 2:
          exit_with_error('USE_PTHREADS=2 is not longer supported')
        if shared.Settings.ALLOW_MEMORY_GROWTH:
          if not shared.Settings.WASM:
            exit_with_error('Memory growth is not supported with pthreads without wasm')
          else:
            logging.warning('USE_PTHREADS + ALLOW_MEMORY_GROWTH may run non-wasm code slowly, see https://github.com/WebAssembly/design/issues/1271')
        # UTF8Decoder.decode doesn't work with a view of a SharedArrayBuffer
        shared.Settings.TEXTDECODER = 0
        options.js_libraries.append(shared.path_from_root('src', 'library_pthread.js'))
        newargs.append('-D__EMSCRIPTEN_PTHREADS__=1')
        if shared.Settings.WASM_BACKEND:
          newargs += ['-pthread']
          # some pthreads code is in asm.js library functions, which are auto-exported; for the wasm backend, we must
          # manually export them
          shared.Settings.EXPORTED_FUNCTIONS += ['_emscripten_get_global_libc', '___pthread_tsd_run_dtors', '__register_pthread_ptr', '_pthread_self', '___emscripten_pthread_data_constructor']
  
        # set location of worker.js
        shared.Settings.PTHREAD_WORKER_FILE = unsuffixed(os.path.basename(target)) + '.worker.js'
      else:
        options.js_libraries.append(shared.path_from_root('src', 'library_pthread_stub.js'))
  
      if shared.Settings.FORCE_FILESYSTEM and not shared.Settings.MINIMAL_RUNTIME:
        # when the filesystem is forced, we export by default methods that filesystem usage
        # may need, including filesystem usage from standalone file packager output (i.e.
        # file packages not built together with emcc, but that are loaded at runtime
        # separately, and they need emcc's output to contain the support they need)
        if not shared.Settings.ASMFS:
          shared.Settings.EXPORTED_RUNTIME_METHODS += [
            'FS_createFolder',
            'FS_createPath',
            'FS_createDataFile',
            'FS_createPreloadedFile',
            'FS_createLazyFile',
            'FS_createLink',
            'FS_createDevice',
            'FS_unlink'
          ]
  
        shared.Settings.EXPORTED_RUNTIME_METHODS += [
          'getMemory',
          'addRunDependency',
          'removeRunDependency',
          'calledRun',
        ]
  
      if shared.Settings.USE_PTHREADS:
        # To ensure allocated thread stacks are aligned:
        shared.Settings.EXPORTED_FUNCTIONS += ['_memalign']
  
        if shared.Settings.MODULARIZE:
          # MODULARIZE+USE_PTHREADS mode requires extra exports out to Module so that worker.js
          # can access them:
  
          # general threading variables:
          shared.Settings.EXPORTED_RUNTIME_METHODS += ['PThread', 'ExitStatus']
  
          # pthread stack setup:
          shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$establishStackSpaceInJsModule']
          shared.Settings.EXPORTED_FUNCTIONS += ['establishStackSpaceInJsModule']
  
          # stack check:
          if shared.Settings.STACK_OVERFLOW_CHECK:
            shared.Settings.EXPORTED_RUNTIME_METHODS += ['writeStackCookie', 'checkStackCookie']
  
        if shared.Settings.LINKABLE:
          exit_with_error('-s LINKABLE=1 is not supported with -s USE_PTHREADS>0!')
        if shared.Settings.SIDE_MODULE:
          exit_with_error('-s SIDE_MODULE=1 is not supported with -s USE_PTHREADS>0!')
        if shared.Settings.MAIN_MODULE:
          exit_with_error('-s MAIN_MODULE=1 is not supported with -s USE_PTHREADS>0!')
        if shared.Settings.EMTERPRETIFY:
          exit_with_error('-s EMTERPRETIFY=1 is not supported with -s USE_PTHREADS>0!')
        if shared.Settings.PROXY_TO_WORKER:
          exit_with_error('--proxy-to-worker is not supported with -s USE_PTHREADS>0! Use the option -s PROXY_TO_PTHREAD=1 if you want to run the main thread of a multithreaded application in a web worker.')
      else:
        if shared.Settings.PROXY_TO_PTHREAD:
          exit_with_error('-s PROXY_TO_PTHREAD=1 requires -s USE_PTHREADS to work!')
  
      # Enable minification of asm.js imports on -O1 and higher if -g1 or lower is used.
      if options.opt_level >= 1 and options.debug_level < 2 and not shared.Settings.WASM:
        shared.Settings.MINIFY_ASMJS_IMPORT_NAMES = 1
  
      if shared.Settings.WASM:
        if not shared.Building.need_asm_js_file():
          asm_target = asm_target.replace('.asm.js', '.temp.asm.js')
          misc_temp_files.note(asm_target)
  
      if shared.Settings.WASM:
        if shared.Settings.TOTAL_MEMORY % 65536 != 0:
          exit_with_error('For wasm, TOTAL_MEMORY must be a multiple of 64KB, was ' + str(shared.Settings.TOTAL_MEMORY))
      else:
        if shared.Settings.TOTAL_MEMORY < 16 * 1024 * 1024:
          exit_with_error('TOTAL_MEMORY must be at least 16MB, was ' + str(shared.Settings.TOTAL_MEMORY))
        if shared.Settings.TOTAL_MEMORY % (16 * 1024 * 1024) != 0:
          exit_with_error('For asm.js, TOTAL_MEMORY must be a multiple of 16MB, was ' + str(shared.Settings.TOTAL_MEMORY))
      if shared.Settings.TOTAL_MEMORY < shared.Settings.TOTAL_STACK:
        exit_with_error('TOTAL_MEMORY must be larger than TOTAL_STACK, was ' + str(shared.Settings.TOTAL_MEMORY) + ' (TOTAL_STACK=' + str(shared.Settings.TOTAL_STACK) + ')')
      if shared.Settings.WASM_MEM_MAX != -1 and shared.Settings.WASM_MEM_MAX % 65536 != 0:
        exit_with_error('WASM_MEM_MAX must be a multiple of 64KB, was ' + str(shared.Settings.WASM_MEM_MAX))
      if shared.Settings.MEMORY_GROWTH_STEP != -1 and shared.Settings.MEMORY_GROWTH_STEP % 65536 != 0:
        exit_with_error('MEMORY_GROWTH_STEP must be a multiple of 64KB, was ' + str(shared.Settings.MEMORY_GROWTH_STEP))
      if shared.Settings.USE_PTHREADS and shared.Settings.WASM and shared.Settings.ALLOW_MEMORY_GROWTH and shared.Settings.WASM_MEM_MAX == -1:
        exit_with_error('If pthreads and memory growth are enabled, WASM_MEM_MAX must be set')
  
      if shared.Settings.EXPORT_ES6 and not shared.Settings.MODULARIZE:
        exit_with_error('EXPORT_ES6 requires MODULARIZE to be set')
  
      # When MODULARIZE option is used, currently declare all module exports
      # individually - TODO: this could be optimized
      if shared.Settings.MODULARIZE and not shared.Settings.DECLARE_ASM_MODULE_EXPORTS:
        shared.Settings.DECLARE_ASM_MODULE_EXPORTS = 1
        logger.warning('Enabling -s DECLARE_ASM_MODULE_EXPORTS=1, since MODULARIZE currently requires declaring asm.js/wasm module exports in full')
  
      # In MINIMAL_RUNTIME when modularizing, by default output asm.js module under the same name as the JS module. This allows code to share same loading function for both JS and asm.js modules,
      # to save code size. The intent is that loader code captures the function variable from global scope to XHR loader local scope when it finishes loading, to avoid polluting global JS scope with
      # variables. This provides safety via encapsulation. See src/shell_minimal_runtime.html for an example.
      if shared.Settings.MINIMAL_RUNTIME and not shared.Settings.SEPARATE_ASM_MODULE_NAME and not shared.Settings.WASM and shared.Settings.MODULARIZE:
        shared.Settings.SEPARATE_ASM_MODULE_NAME = 'var ' + shared.Settings.EXPORT_NAME
  
      if shared.Settings.MODULARIZE and shared.Settings.SEPARATE_ASM and not shared.Settings.WASM and not shared.Settings.SEPARATE_ASM_MODULE_NAME:
        exit_with_error('Targeting asm.js with --separate-asm and -s MODULARIZE=1 requires specifying the target variable name to which the asm.js module is loaded into. See https://github.com/emscripten-core/emscripten/pull/7949 for details')
      # Apply default option if no custom name is provided
      if not shared.Settings.SEPARATE_ASM_MODULE_NAME:
        shared.Settings.SEPARATE_ASM_MODULE_NAME = 'Module["asm"]'
      elif shared.Settings.WASM:
        exit_with_error('-s SEPARATE_ASM_MODULE_NAME option only applies to when targeting asm.js, not with WebAssembly!')
  
      if shared.Settings.MINIMAL_RUNTIME:
        # Minimal runtime uses a different default shell file
        if options.shell_path == shared.path_from_root('src', 'shell.html'):
          options.shell_path = shared.path_from_root('src', 'shell_minimal_runtime.html')
  
        # Remove the default exported functions 'memcpy', 'memset', 'malloc', 'free', etc. - those should only be linked in if used
        shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE = []
  
        if shared.Settings.ASSERTIONS and shared.Settings.MINIMAL_RUNTIME:
          # In ASSERTIONS-builds, functions UTF8ArrayToString() and stringToUTF8Array() (which are not JS library functions), both
          # use warnOnce(), which in MINIMAL_RUNTIME is a JS library function, so explicitly have to mark dependency to warnOnce()
          # in that case. If string functions are turned to library functions in the future, then JS dependency tracking can be
          # used and this special directive can be dropped.
          shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$warnOnce']
  
        # Always use the new HTML5 API event target lookup rules
        shared.Settings.DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR = 1
  
        # Require explicit -lfoo.js flags to link with JS libraries.
        shared.Settings.AUTO_JS_LIBRARIES = 0
  
        # In asm.js always use memory init file to get the best code size, other modes are not currently supported.
        if not shared.Settings.WASM:
          options.memory_init_file = True
  
      if shared.Settings.MODULARIZE and not shared.Settings.MODULARIZE_INSTANCE and shared.Settings.EXPORT_NAME == 'Module' and final_suffix == '.html' and \
         (options.shell_path == shared.path_from_root('src', 'shell.html') or options.shell_path == shared.path_from_root('src', 'shell_minimal.html')):
        exit_with_error('Due to collision in variable name "Module", the shell file "' + options.shell_path + '" is not compatible with build options "-s MODULARIZE=1 -s EXPORT_NAME=Module". Either provide your own shell file, change the name of the export to something else to avoid the name collision. (see https://github.com/emscripten-core/emscripten/issues/7950 for details)')
  
      if shared.Settings.WASM:
        if shared.Settings.SINGLE_FILE:
          # placeholder strings for JS glue, to be replaced with subresource locations in do_binaryen
          shared.Settings.WASM_TEXT_FILE = shared.FilenameReplacementStrings.WASM_TEXT_FILE
          shared.Settings.WASM_BINARY_FILE = shared.FilenameReplacementStrings.WASM_BINARY_FILE
          shared.Settings.ASMJS_CODE_FILE = shared.FilenameReplacementStrings.ASMJS_CODE_FILE
        else:
          # set file locations, so that JS glue can find what it needs
          shared.Settings.WASM_TEXT_FILE = shared.JS.escape_for_js_string(os.path.basename(wasm_text_target))
          shared.Settings.WASM_BINARY_FILE = shared.JS.escape_for_js_string(os.path.basename(wasm_binary_target))
          shared.Settings.ASMJS_CODE_FILE = shared.JS.escape_for_js_string(os.path.basename(asm_target))
        shared.Settings.ASM_JS = 2 # when targeting wasm, we use a wasm Memory, but that is not compatible with asm.js opts
        if shared.Settings.ELIMINATE_DUPLICATE_FUNCTIONS:
          logger.warning('for wasm there is no need to set ELIMINATE_DUPLICATE_FUNCTIONS, the binaryen optimizer does it automatically')
          shared.Settings.ELIMINATE_DUPLICATE_FUNCTIONS = 0
        # default precise-f32 to on, since it works well in wasm
        shared.Settings.PRECISE_F32 = 1
        if options.js_opts and not options.force_js_opts:
          options.js_opts = None
          logger.debug('asm.js opts not forced by user or an option that depends them, and we do not intend to run the asm.js, so disabling and leaving opts to the binaryen optimizer')
        if options.use_closure_compiler == 2 and not shared.Settings.WASM2JS:
          exit_with_error('closure compiler mode 2 assumes the code is asm.js, so not meaningful for wasm')
        if any(s.startswith('MEM_INIT_METHOD=') for s in settings_changes):
          exit_with_error('MEM_INIT_METHOD is not supported in wasm. Memory will be embedded in the wasm binary if threads are not used, and included in a separate file if threads are used.')
        if shared.Settings.WASM2JS:
          shared.Settings.MAYBE_WASM2JS = 1
          # wasm2js does not support passive segments or atomics
          if shared.Settings.USE_PTHREADS:
            exit_with_error('WASM2JS does not yet support pthreads')
          # in wasm2js, keep the mem init in the wasm itself if we can and if the
          # options wouldn't tell a js build to use a separate mem init file
          shared.Settings.MEM_INIT_IN_WASM = not options.memory_init_file or shared.Settings.SINGLE_FILE
        else:
          # wasm includes the mem init in the wasm binary. The exception is
          # wasm2js, which behaves more like js.
          options.memory_init_file = True
          shared.Settings.MEM_INIT_IN_WASM = True if shared.Settings.WASM_BACKEND else not shared.Settings.USE_PTHREADS
  
        # WASM_ASYNC_COMPILATION and SWAPPABLE_ASM_MODULE do not have a meaning in MINIMAL_RUNTIME (always async)
        if not shared.Settings.MINIMAL_RUNTIME:
          if shared.Settings.WASM_ASYNC_COMPILATION == 1:
            # async compilation requires a swappable module - we swap it in when it's ready
            shared.Settings.SWAPPABLE_ASM_MODULE = 1
          else:
            # if not wasm-only, we can't do async compilation as the build can run in other
            # modes than wasm (like asm.js) which may not support an async step
            shared.Settings.WASM_ASYNC_COMPILATION = 0
            warning = 'This will reduce performance and compatibility (some browsers limit synchronous compilation), see http://kripken.github.io/emscripten-site/docs/compiling/WebAssembly.html#codegen-effects'
            if 'WASM_ASYNC_COMPILATION=1' in settings_changes:
              logger.warning('WASM_ASYNC_COMPILATION requested, but disabled because of user options. ' + warning)
            elif 'WASM_ASYNC_COMPILATION=0' not in settings_changes:
              logger.warning('WASM_ASYNC_COMPILATION disabled due to user options. ' + warning)
  
        if not shared.Settings.DECLARE_ASM_MODULE_EXPORTS:
          # Swappable wasm module/asynchronous wasm compilation requires an indirect stub
          # function generated to each function export from wasm module, so cannot use the
          # concise form of grabbing exports that does not need to refer to each export individually.
          if shared.Settings.SWAPPABLE_ASM_MODULE == 1:
            shared.Settings.DECLARE_ASM_MODULE_EXPORTS = 1
            logger.warning('Enabling -s DECLARE_ASM_MODULE_EXPORTS=1 since -s SWAPPABLE_ASM_MODULE=1 is used')
  
        # wasm side modules have suffix .wasm
        if shared.Settings.SIDE_MODULE and target.endswith('.js'):
          logger.warning('output suffix .js requested, but wasm side modules are just wasm files; emitting only a .wasm, no .js')
  
        if options.separate_asm:
          exit_with_error('cannot --separate-asm when emitting wasm, since not emitting asm.js')
  
        sanitize = set()
  
        for arg in newargs:
          if arg.startswith('-fsanitize='):
            sanitize.update(arg.split('=', 1)[1].split(','))
          elif arg.startswith('-fno-sanitize='):
            sanitize.difference_update(arg.split('=', 1)[1].split(','))
  
        if sanitize:
          shared.Settings.USE_OFFSET_CONVERTER = 1
  
          if not shared.Settings.WASM_BACKEND:
            exit_with_error('Sanitizers are not compatible with the fastcomp backend. Please upgrade to the upstream wasm backend by following these instructions: https://v8.dev/blog/emscripten-llvm-wasm#testing')
  
        if sanitize & UBSAN_SANITIZERS:
          if '-fsanitize-minimal-runtime' in newargs:
            shared.Settings.UBSAN_RUNTIME = 1
          else:
            shared.Settings.UBSAN_RUNTIME = 2
  
        if 'leak' in sanitize:
          shared.Settings.USE_LSAN = 1
          shared.Settings.EXIT_RUNTIME = 1
  
          if shared.Settings.LINKABLE:
            exit_with_error('LSan does not support dynamic linking')
  
        if 'address' in sanitize:
          shared.Settings.USE_ASAN = 1
  
          shared.Settings.GLOBAL_BASE = shared.Settings.ASAN_SHADOW_SIZE
          shared.Settings.TOTAL_MEMORY += shared.Settings.ASAN_SHADOW_SIZE
          assert shared.Settings.TOTAL_MEMORY < 2**32
  
          if shared.Settings.SAFE_HEAP:
            # SAFE_HEAP instruments ASan's shadow memory accesses.
            # Since the shadow memory starts at 0, the act of accessing the shadow memory is detected
            # by SAFE_HEAP as a null pointer dereference.
            exit_with_error('ASan does not work with SAFE_HEAP')
  
          if shared.Settings.LINKABLE:
            exit_with_error('ASan does not support dynamic linking')
  
        if sanitize and '-g4' in args:
          shared.Settings.LOAD_SOURCE_MAP = 1
  
        if shared.Settings.WASM_BACKEND:
          options.js_opts = None
  
          # wasm backend output can benefit from the binaryen optimizer (in asm2wasm,
          # we run the optimizer during asm2wasm itself). use it, if not overridden.
  
          # BINARYEN_PASSES and BINARYEN_EXTRA_PASSES are comma-separated, and we support both '-'-prefixed and unprefixed pass names
          def parse_passes(string):
            passes = string.split(',')
            passes = [('--' + p) if p[0] != '-' else p for p in passes if p]
            return passes
  
          passes = []
          if 'BINARYEN_PASSES' in settings_key_changes:
            if shared.Settings.BINARYEN_PASSES:
              passes += parse_passes(shared.Settings.BINARYEN_PASSES)
          else:
            # safe heap must run before post-emscripten, so post-emscripten can apply the sbrk ptr
            if shared.Settings.SAFE_HEAP:
              passes += ['--safe-heap']
            passes += ['--post-emscripten']
            if not shared.Settings.EXIT_RUNTIME:
              passes += ['--no-exit-runtime']
            if options.opt_level > 0 or options.shrink_level > 0:
              passes += [shared.Building.opt_level_to_str(options.opt_level, options.shrink_level)]
            elif shared.Settings.STANDALONE_WASM:
              # even if not optimizing, make an effort to remove all unused imports and
              # exports, to make the wasm as standalone as possible
              passes += ['--remove-unused-module-elements']
            if shared.Settings.GLOBAL_BASE >= 1024: # hardcoded value in the binaryen pass
              passes += ['--low-memory-unused']
            if options.debug_level < 3:
              passes += ['--strip-debug']
            if not shared.Settings.EMIT_PRODUCERS_SECTION:
              passes += ['--strip-producers']
            if shared.Settings.AUTODEBUG and shared.Settings.WASM_OBJECT_FILES:
              # adding '--flatten' here may make these even more effective
              passes += ['--instrument-locals']
              passes += ['--log-execution']
              passes += ['--instrument-memory']
              passes += ['--legalize-js-interface']
            if shared.Settings.EMULATE_FUNCTION_POINTER_CASTS:
              # note that this pass must run before asyncify, as if it runs afterwards we only
              # generate the  byn$fpcast_emu  functions after asyncify runs, and so we wouldn't
              # be able to whitelist them etc.
              passes += ['--fpcast-emu']
            if shared.Settings.ASYNCIFY:
              # TODO: allow whitelist as in asyncify
              passes += ['--asyncify']
              if shared.Settings.ASYNCIFY_IGNORE_INDIRECT:
                passes += ['--pass-arg=asyncify-ignore-indirect']
              else:
                # if we are not ignoring indirect calls, then we must treat invoke_* as if
                # they are indirect calls, since that is what they do - we can't see their
                # targets statically.
                shared.Settings.ASYNCIFY_IMPORTS += ['invoke_*']
              # with pthreads we may call main through the __call_main mechanism, which can
              # therefore reach anything in the program, so mark it as possibly causing a
              # sleep (the asyncify analysis doesn't look through JS, just wasm, so it can't
              # see what it itself calls)
              if shared.Settings.USE_PTHREADS:
                shared.Settings.ASYNCIFY_IMPORTS += ['__call_main']
              if shared.Settings.ASYNCIFY_IMPORTS:
                passes += ['--pass-arg=asyncify-imports@%s' % ','.join(['env.' + i for i in shared.Settings.ASYNCIFY_IMPORTS])]
  
              # shell escaping can be confusing; try to emit useful warnings
              def check_human_readable_list(items):
                for item in items:
                  if item.count('(') != item.count(')'):
                    logger.warning('''emcc: ASYNCIFY list contains an item without balanced parentheses ("(", ")"):''')
                    logger.warning('''   ''' + item)
                    logger.warning('''This may indicate improper escaping that led to splitting inside your names.''')
                    logger.warning('''Try to quote the entire argument, like this: -s 'ASYNCIFY_WHITELIST=["foo(int, char)", "bar"]' ''')
                    break
  
              if shared.Settings.ASYNCIFY_BLACKLIST:
                check_human_readable_list(shared.Settings.ASYNCIFY_BLACKLIST)
                passes += ['--pass-arg=asyncify-blacklist@%s' % ','.join(shared.Settings.ASYNCIFY_BLACKLIST)]
              if shared.Settings.ASYNCIFY_WHITELIST:
                check_human_readable_list(shared.Settings.ASYNCIFY_WHITELIST)
                passes += ['--pass-arg=asyncify-whitelist@%s' % ','.join(shared.Settings.ASYNCIFY_WHITELIST)]
            if shared.Settings.BINARYEN_IGNORE_IMPLICIT_TRAPS:
              passes += ['--ignore-implicit-traps']
          if shared.Settings.BINARYEN_EXTRA_PASSES:
            passes += parse_passes(shared.Settings.BINARYEN_EXTRA_PASSES)
          options.binaryen_passes = passes
  
          # to bootstrap struct_info, we need binaryen
          os.environ['EMCC_WASM_BACKEND_BINARYEN'] = '1'
  
        # run safe-heap as a binaryen pass in fastcomp wasm, while in the wasm backend we
        # run it in binaryen_passes so that it can be synchronized with the sbrk ptr
        if shared.Settings.SAFE_HEAP and shared.Building.is_wasm_only() and not shared.Settings.WASM_BACKEND:
          options.binaryen_passes += ['--safe-heap']
        if shared.Settings.EMULATE_FUNCTION_POINTER_CASTS and not shared.Settings.WASM_BACKEND:
          # emulated function pointer casts is emulated in fastcomp wasm using a binaryen pass
          options.binaryen_passes += ['--fpcast-emu']
          # we also need emulated function pointers for that, as we need a single flat
          # table, as is standard in wasm, and not asm.js split ones.
          shared.Settings.EMULATED_FUNCTION_POINTERS = 1
  
      if shared.Settings.WASM2JS:
        if not shared.Settings.WASM_BACKEND:
          exit_with_error('wasm2js is only available in the upstream wasm backend path')
        if use_source_map(options):
          exit_with_error('wasm2js does not support source maps yet (debug in wasm for now)')
  
      if target.endswith(WASM_ENDINGS):
        # if the output is just a wasm file, it will normally be a standalone one,
        # as there is no JS. an exception are side modules, as we can't tell at
        # compile time whether JS will be involved or not - the main module may
        # have JS, and the side module is expected to link against that.
        # we also do not support standalone mode in fastcomp.
        if shared.Settings.WASM_BACKEND and not shared.Settings.SIDE_MODULE:
          shared.Settings.STANDALONE_WASM = 1
        js_target = misc_temp_files.get(suffix='.js').name
  
      if shared.Settings.EVAL_CTORS:
        if not shared.Settings.WASM:
          # for asm.js: this option is not a js optimizer pass, but does run the js optimizer internally, so
          # we need to generate proper code for that (for wasm, we run a binaryen tool for this)
          shared.Settings.RUNNING_JS_OPTS = 1
  
      # memory growth does not work in dynamic linking, except for wasm
      if not shared.Settings.WASM and (shared.Settings.MAIN_MODULE or shared.Settings.SIDE_MODULE):
        assert not shared.Settings.ALLOW_MEMORY_GROWTH, 'memory growth is not supported with shared asm.js modules'
  
      if shared.Settings.MINIMAL_RUNTIME:
        if shared.Settings.ALLOW_MEMORY_GROWTH:
          logging.warning('-s ALLOW_MEMORY_GROWTH=1 is not yet supported with -s MINIMAL_RUNTIME=1')
  
        if shared.Settings.EMTERPRETIFY:
          exit_with_error('-s EMTERPRETIFY=1 is not supported with -s MINIMAL_RUNTIME=1')
  
        if shared.Settings.USE_PTHREADS:
          exit_with_error('-s USE_PTHREADS=1 is not yet supported with -s MINIMAL_RUNTIME=1')
  
        if shared.Settings.PRECISE_F32 == 2:
          exit_with_error('-s PRECISE_F32=2 is not supported with -s MINIMAL_RUNTIME=1')
  
        if shared.Settings.SINGLE_FILE:
          exit_with_error('-s SINGLE_FILE=1 is not supported with -s MINIMAL_RUNTIME=1')
  
      if shared.Settings.ALLOW_MEMORY_GROWTH and shared.Settings.ASM_JS == 1:
        # this is an issue in asm.js, but not wasm
        if not shared.Settings.WASM:
          shared.WarningManager.warn('ALMOST_ASM')
          shared.Settings.ASM_JS = 2 # memory growth does not validate as asm.js http://discourse.wicg.io/t/request-for-comments-switching-resizing-heaps-in-asm-js/641/23
  
      # safe heap in asm.js uses the js optimizer (in wasm-only mode we can use binaryen)
      if shared.Settings.SAFE_HEAP and not shared.Building.is_wasm_only():
        if not options.js_opts:
          logger.debug('enabling js opts for SAFE_HEAP')
          options.js_opts = True
        options.force_js_opts = True
  
      if options.js_opts:
        shared.Settings.RUNNING_JS_OPTS = 1
  
      if shared.Settings.CYBERDWARF:
        newargs.append('-g')
        options.debug_level = max(options.debug_level, 2)
        shared.Settings.BUNDLED_CD_DEBUG_FILE = target + ".cd"
        options.js_libraries.append(shared.path_from_root('src', 'library_cyberdwarf.js'))
        options.js_libraries.append(shared.path_from_root('src', 'library_debugger_toolkit.js'))
  
      if options.tracing:
        if shared.Settings.ALLOW_MEMORY_GROWTH:
          shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['emscripten_trace_report_memory_layout']
  
      # MINIMAL_RUNTIME always use separate .asm.js file for best performance and memory usage
      if shared.Settings.MINIMAL_RUNTIME and not shared.Settings.WASM:
        options.separate_asm = True
  
      if shared.Settings.STANDALONE_WASM:
        if not shared.Settings.WASM_BACKEND:
          exit_with_error('STANDALONE_WASM is only available in the upstream wasm backend path')
        if shared.Settings.USE_PTHREADS:
          exit_with_error('STANDALONE_WASM does not support pthreads yet')
        if shared.Settings.SIMD:
          exit_with_error('STANDALONE_WASM does not support simd yet')
        if shared.Settings.ALLOW_MEMORY_GROWTH:
          exit_with_error('STANDALONE_WASM does not support memory growth yet')
        # the wasm must be runnable without the JS, so there cannot be anything that
        # requires JS legalization
        shared.Settings.LEGALIZE_JS_FFI = 0
  
      if shared.Settings.WASM_BACKEND:
        if shared.Settings.SIMD:
          newargs.append('-msimd128')
        if shared.Settings.USE_PTHREADS:
          newargs.append('-pthread')
      else:
        # We leave the -O option in place so that the clang front-end runs in that
        # optimization mode, but we disable the actual optimization passes, as we'll
        # run them separately.
        if options.opt_level > 0:
          newargs.append('-mllvm')
          newargs.append('-disable-llvm-optzns')
  
      if not shared.Settings.LEGALIZE_JS_FFI:
        assert shared.Building.is_wasm_only(), 'LEGALIZE_JS_FFI incompatible with RUNNING_JS_OPTS.'
  
      shared.Settings.EMSCRIPTEN_VERSION = shared.EMSCRIPTEN_VERSION
      shared.Settings.OPT_LEVEL = options.opt_level
      shared.Settings.DEBUG_LEVEL = options.debug_level
      shared.Settings.PROFILING_FUNCS = options.profiling_funcs
      shared.Settings.SOURCE_MAP_BASE = options.source_map_base or ''
  
      ## Compile source code to bitcode
  
      logger.debug('compiling to bitcode')
  
      temp_files = []
  
    # exit block 'parse arguments and setup'
    log_time('parse arguments and setup')
  
    if DEBUG:
      # we are about to start using temp dirs. serialize access to the temp dir
      # when using EMCC_DEBUG, since we don't want multiple processes would to
      # use it at once, they might collide if they happen to use the same
      # tempfile names
      shared.Cache.acquire_cache_lock()
  
    try:
      with ToolchainProfiler.profile_block('compile inputs'):
        # Precompiled headers support
        if has_header_inputs:
          headers = [header for _, header in input_files]
          for header in headers:
            assert header.endswith(HEADER_ENDINGS), 'if you have one header input, we assume you want to precompile headers, and cannot have source files or other inputs as well: ' + str(headers) + ' : ' + header
          args = newargs + headers
          if specified_target:
            args += ['-o', specified_target]
          args = system_libs.process_args(args, shared.Settings)
          logger.debug("running (for precompiled headers): " + clang_compiler + ' ' + ' '.join(args))
          return run_process([clang_compiler] + args, check=False).returncode
  
        # Request LLVM debug info if explicitly specified, or building bitcode with -g, or if building a source all the way to JS with -g
        if use_source_map(options) or ((final_suffix not in JS_CONTAINING_ENDINGS or (has_source_inputs and final_suffix in JS_CONTAINING_ENDINGS)) and options.requested_debug == '-g'):
          # do not save llvm debug info if js optimizer will wipe it out anyhow (but if source maps are used, keep it)
          if use_source_map(options) or not (final_suffix in JS_CONTAINING_ENDINGS and options.js_opts):
            newargs.append('-g') # preserve LLVM debug info
            options.debug_level = 4
            shared.Settings.DEBUG_LEVEL = 4
  
        # For asm.js, the generated JavaScript could preserve LLVM value names, which can be useful for debugging.
        if options.debug_level >= 3 and not shared.Settings.WASM:
          newargs.append('-fno-discard-value-names')
  
        def is_link_flag(flag):
          return any(flag.startswith(x) for x in ('-l', '-L', '-Wl,'))
  
        compile_args = [a for a in newargs if a and not is_link_flag(a)]
  
        # Bitcode args generation code
        def get_clang_command(input_files):
          args = [clang_compiler] + compile_args + input_files
          if not shared.Building.can_inline():
            args.append('-fno-inline-functions')
          # For fastcomp backend, no LLVM IR functions should ever be annotated
          # 'optnone', because that would skip running the SimplifyCFG pass on
          # them, which is required to always run to clean up LandingPadInst
          # instructions that are not needed.
          if not shared.Settings.WASM_BACKEND:
            args += ['-Xclang', '-disable-O0-optnone']
          args = system_libs.process_args(args, shared.Settings)
          return args
  
        # -E preprocessor-only support
        if '-E' in newargs or '-M' in newargs or '-MM' in newargs or '-fsyntax-only' in newargs:
          input_files = [x[1] for x in input_files]
          cmd = get_clang_command(input_files)
          if specified_target:
            cmd += ['-o', specified_target]
          # Do not compile, but just output the result from preprocessing stage or
          # output the dependency rule. Warning: clang and gcc behave differently
          # with -MF! (clang seems to not recognize it)
          logger.debug(('just preprocessor ' if '-E' in newargs else 'just dependencies: ') + ' '.join(cmd))
          return run_process(cmd, check=False).returncode
  
        def get_object_filename(input_file):
          if compile_only and len(input_files) == 1:
            # no need for a temp file, just emit to the right place
            if specified_target:
              return specified_target
            else:
              return unsuffixed_basename(input_files[0][1]) + options.default_object_extension
          else:
            return in_temp(unsuffixed(uniquename(input_file)) + options.default_object_extension)
  
        def compile_source_file(i, input_file):
          logger.debug('compiling source file: ' + input_file)
          output_file = get_object_filename(input_file)
          temp_files.append((i, output_file))
          cmd = get_clang_command([input_file]) + ['-c', '-o', output_file]
          if shared.Settings.WASM_BACKEND and shared.Settings.RELOCATABLE:
            cmd.append('-fPIC')
            cmd.append('-fvisibility=default')
          if shared.Settings.WASM_OBJECT_FILES:
            for a in shared.Building.llvm_backend_args():
              cmd += ['-mllvm', a]
          else:
            cmd.append('-emit-llvm')
          shared.print_compiler_stage(cmd)
          shared.check_call(cmd)
          if output_file != '-':
            assert(os.path.exists(output_file))
  
        # First, generate LLVM bitcode. For each input file, we get base.o with bitcode
        for i, input_file in input_files:
          file_ending = get_file_suffix(input_file)
          if file_ending.endswith(SOURCE_ENDINGS):
            compile_source_file(i, input_file)
          else:
            if file_ending.endswith(OBJECT_FILE_ENDINGS):
              logger.debug('using object file: ' + input_file)
              temp_files.append((i, input_file))
            elif file_ending.endswith(DYNAMICLIB_ENDINGS) or shared.Building.is_ar(input_file):
              logger.debug('using library file: ' + input_file)
              temp_files.append((i, input_file))
            elif file_ending.endswith(ASSEMBLY_ENDINGS):
              if not LEAVE_INPUTS_RAW:
                logger.debug('assembling assembly file: ' + input_file)
                temp_file = in_temp(unsuffixed(uniquename(input_file)) + '.o')
                shared.Building.llvm_as(input_file, temp_file)
                temp_files.append((i, temp_file))
            else:
              if has_fixed_language_mode:
                compile_source_file(i, input_file)
              else:
                exit_with_error(input_file + ': Unknown file suffix when compiling to LLVM bitcode!')
  
      # exit block 'compile inputs'
      log_time('compile inputs')
  
      with ToolchainProfiler.profile_block('process inputs'):
        if not LEAVE_INPUTS_RAW and not shared.Settings.WASM_BACKEND:
          assert len(temp_files) == len(input_files)
  
          # Optimize source files
          if optimizing(options.llvm_opts):
            for pos, (_, input_file) in enumerate(input_files):
              file_ending = get_file_suffix(input_file)
              if file_ending.endswith(SOURCE_ENDINGS):
                temp_file = temp_files[pos][1]
                logger.debug('optimizing %s', input_file)
                # if DEBUG:
                #   shutil.copyfile(temp_file, os.path.join(shared.configuration.CANONICAL_TEMP_DIR, 'to_opt.bc')) # useful when LLVM opt aborts
                new_temp_file = in_temp(unsuffixed(uniquename(temp_file)) + '.o')
                # after optimizing, lower intrinsics to libc calls so that our linking code
                # will find them (otherwise, llvm.cos.f32() will not link in cosf(), and
                # we end up calling out to JS for Math.cos).
                opts = options.llvm_opts + ['-lower-non-em-intrinsics']
                shared.Building.llvm_opt(temp_file, opts, new_temp_file)
                temp_files[pos] = (temp_files[pos][0], new_temp_file)
  
        # If we were just compiling stop here
        if compile_only:
          if not specified_target:
            assert len(temp_files) == len(input_files)
            for tempf, inputf in zip(temp_files, input_files):
              safe_move(tempf[1], unsuffixed_basename(inputf[1]) + final_suffix)
          else:
            # Specifying -o with multiple input source files is not allowed.
            # We error out much earlier in this case.
            assert len(input_files) == 1
            input_file = input_files[0][1]
            temp_file = temp_files[0][1]
            bitcode_target = specified_target if specified_target else unsuffixed_basename(input_file) + final_suffix
            if temp_file != input_file:
              safe_move(temp_file, bitcode_target)
            else:
              shutil.copyfile(temp_file, bitcode_target)
            temp_output_base = unsuffixed(temp_file)
            if os.path.exists(temp_output_base + '.d'):
              # There was a .d file generated, from -MD or -MMD and friends, save a copy of it to where the output resides,
              # adjusting the target name away from the temporary file name to the specified target.
              # It will be deleted with the rest of the temporary directory.
              deps = open(temp_output_base + '.d').read()
              deps = deps.replace(temp_output_base + options.default_object_extension, specified_target)
              with open(os.path.join(os.path.dirname(specified_target), os.path.basename(unsuffixed(input_file) + '.d')), "w") as out_dep:
                out_dep.write(deps)
  
      # exit block 'process inputs'
      log_time('process inputs')
  
      if compile_only:
        logger.debug('stopping after compile phase')
        return 0
  
      # Decide what we will link
      consumed = process_libraries(libs, lib_dirs, temp_files)
      # Filter out libraries that are actually JS libs
      link_flags = [l for l in link_flags if l[0] not in consumed]
      temp_files = filter_out_dynamic_libs(temp_files)
  
      linker_inputs = [val for _, val in sorted(temp_files + link_flags)]
  
      if link_to_object:
        with ToolchainProfiler.profile_block('linking to object file'):
          # We have a specified target (-o <target>), which is not JavaScript or HTML, and
          # we have multiple files: Link them
          if shared.Settings.SIDE_MODULE:
            exit_with_error('SIDE_MODULE must only be used when compiling to an executable shared library, and not when emitting an object file.  That is, you should be emitting a .wasm file (for wasm) or a .js file (for asm.js). Note that when compiling to a typical native suffix for a shared library (.so, .dylib, .dll; which many build systems do) then Emscripten emits an object file, which you should then compile to .wasm or .js with SIDE_MODULE.')
          if final_suffix.lower() in ('.so', '.dylib', '.dll'):
            logger.warning('When Emscripten compiles to a typical native suffix for shared libraries (.so, .dylib, .dll) then it emits an object file. You should then compile that to an emscripten SIDE_MODULE (using that flag) with suffix .wasm (for wasm) or .js (for asm.js). (You may also want to adapt your build system to emit the more standard suffix for a an object file, \'.bc\' or \'.o\', which would avoid this warning.)')
          logger.debug('link_to_object: ' + str(linker_inputs) + ' -> ' + specified_target)
          shared.Building.link_to_object(linker_inputs, specified_target)
          logger.debug('stopping after linking to object file')
          return 0
  
      ## Continue on to create JavaScript
  
      with ToolchainProfiler.profile_block('calculate system libraries'):
        # link in ports and system libraries, if necessary
        if not LEAVE_INPUTS_RAW and \
           not shared.Settings.BOOTSTRAPPING_STRUCT_INFO and \
           not shared.Settings.SIDE_MODULE: # shared libraries/side modules link no C libraries, need them in parent
          extra_files_to_link = system_libs.get_ports(shared.Settings)
          extra_files_to_link += system_libs.calculate([f for _, f in sorted(temp_files)] + extra_files_to_link, in_temp, stdout_=None, stderr_=None, forced=forced_stdlibs)
          linker_inputs += extra_files_to_link
  
      # exit block 'calculate system libraries'
      log_time('calculate system libraries')
  
      def dedup_list(lst):
        rtn = []
        for item in lst:
          if item not in rtn:
            rtn.append(item)
        return rtn
  
      # Make a final pass over shared.Settings.EXPORTED_FUNCTIONS to remove any
      # duplication between functions added by the driver/libraries and function
      # specified by the user
      shared.Settings.EXPORTED_FUNCTIONS = dedup_list(shared.Settings.EXPORTED_FUNCTIONS)
  
      with ToolchainProfiler.profile_block('link'):
        # final will be an array if linking is deferred, otherwise a normal string.
        if shared.Settings.WASM_BACKEND:
          DEFAULT_FINAL = in_temp(target_basename + '.wasm')
        else:
          DEFAULT_FINAL = in_temp(target_basename + '.bc')
  
        def get_final():
          global final
          if isinstance(final, list):
            final = DEFAULT_FINAL
          return final
  
        # First, combine the bitcode files if there are several. We must also link if we have a singleton .a
        perform_link = len(linker_inputs) > 1 or shared.Settings.WASM_BACKEND
        if not perform_link and not LEAVE_INPUTS_RAW:
          is_bc = suffix(temp_files[0][1]) in OBJECT_FILE_ENDINGS
          is_dylib = suffix(temp_files[0][1]) in DYNAMICLIB_ENDINGS
          is_ar = shared.Building.is_ar(temp_files[0][1])
          perform_link = not (is_bc or is_dylib) and is_ar
        if perform_link:
          logger.debug('linking: ' + str(linker_inputs))
          # force archive contents to all be included, if just archives, or if linking shared modules
          force_archive_contents = all(t.endswith(STATICLIB_ENDINGS) for _, t in temp_files) or shared.Settings.LINKABLE
  
          # if  EMCC_DEBUG=2  then we must link now, so the temp files are complete.
          # if using the wasm backend, we might be using vanilla LLVM, which does not allow our fastcomp deferred linking opts.
          # TODO: we could check if this is a fastcomp build, and still speed things up here
          just_calculate = DEBUG != 2 and not shared.Settings.WASM_BACKEND
          if shared.Settings.WASM_BACKEND:
            # If LTO is enabled then use the -O opt level as the LTO level
            if options.llvm_lto:
              lto_level = options.opt_level
            else:
              lto_level = 0
            final = shared.Building.link_lld(linker_inputs, DEFAULT_FINAL, lto_level=lto_level)
          else:
            final = shared.Building.link(linker_inputs, DEFAULT_FINAL, force_archive_contents=force_archive_contents, just_calculate=just_calculate)
        else:
          logger.debug('skipping linking: ' + str(linker_inputs))
          if not LEAVE_INPUTS_RAW:
            _, temp_file = temp_files[0]
            _, input_file = input_files[0]
            final = in_temp(target_basename + '.bc')
            if temp_file != input_file:
              shutil.move(temp_file, final)
            else:
              shutil.copyfile(temp_file, final)
          else:
            _, input_file = input_files[0]
            final = in_temp(input_file)
            shutil.copyfile(input_file, final)
  
      # exit block 'link'
      log_time('link')
  
      if not shared.Settings.WASM_BACKEND:
        with ToolchainProfiler.profile_block('post-link'):
          if DEBUG:
            logger.debug('saving intermediate processing steps to %s', shared.get_emscripten_temp_dir())
            if not LEAVE_INPUTS_RAW:
              save_intermediate('basebc', 'bc')
  
          # Optimize, if asked to
          if not LEAVE_INPUTS_RAW:
            # remove LLVM debug if we are not asked for it
            link_opts = [] if use_source_map(options) or shared.Settings.CYBERDWARF else ['-strip-debug']
            if not shared.Settings.ASSERTIONS:
              link_opts += ['-disable-verify']
            else:
              # when verifying, LLVM debug info has some tricky linking aspects, and llvm-link will
              # disable the type map in that case. we added linking to opt, so we need to do
              # something similar, which we can do with a param to opt
              link_opts += ['-disable-debug-info-type-map']
  
            if options.llvm_lto is not None and options.llvm_lto >= 2 and optimizing(options.llvm_opts):
              logger.debug('running LLVM opts as pre-LTO')
              final = shared.Building.llvm_opt(final, options.llvm_opts, DEFAULT_FINAL)
              save_intermediate('opt', 'bc')
  
            # If we can LTO, do it before dce, since it opens up dce opportunities
            if (not shared.Settings.LINKABLE) and options.llvm_lto and options.llvm_lto != 2:
              if not shared.Building.can_inline():
                link_opts.append('-disable-inlining')
              # add a manual internalize with the proper things we need to be kept alive during lto
              link_opts += shared.Building.get_safe_internalize() + ['-std-link-opts']
              # execute it now, so it is done entirely before we get to the stage of legalization etc.
              final = shared.Building.llvm_opt(final, link_opts, DEFAULT_FINAL)
              save_intermediate('lto', 'bc')
              link_opts = []
            else:
              # At minimum remove dead functions etc., this potentially saves a
              # lot in the size of the generated code (and the time to compile it)
              link_opts += shared.Building.get_safe_internalize() + ['-globaldce']
  
            if options.cfi:
              if use_cxx:
                 link_opts.append("-wholeprogramdevirt")
              link_opts.append("-lowertypetests")
  
            if AUTODEBUG:
              # let llvm opt directly emit ll, to skip writing and reading all the bitcode
              link_opts += ['-S']
              final = shared.Building.llvm_opt(final, link_opts, get_final() + '.link.ll')
              save_intermediate('linktime', 'll')
            else:
              if len(link_opts) > 0:
                final = shared.Building.llvm_opt(final, link_opts, DEFAULT_FINAL)
                save_intermediate('linktime', 'bc')
              if options.save_bc:
                shutil.copyfile(final, options.save_bc)
  
          # Prepare .ll for Emscripten
          if LEAVE_INPUTS_RAW:
            assert len(input_files) == 1
          if options.save_bc:
            save_intermediate('ll', 'll')
  
          if AUTODEBUG:
            logger.debug('autodebug')
            next = get_final() + '.ad.ll'
            run_process([shared.PYTHON, shared.AUTODEBUGGER, final, next])
            final = next
            save_intermediate('autodebug', 'll')
  
          assert not isinstance(final, list), 'we must have linked the final files, if linking was deferred, by this point'
  
        # exit block 'post-link'
        log_time('post-link')
  
      with ToolchainProfiler.profile_block('emscript'):
        # Emscripten
        logger.debug('LLVM => JS')
        js_libraries = None
        if options.js_libraries:
          js_libraries = [os.path.abspath(lib) for lib in options.js_libraries]
        if options.memory_init_file:
          shared.Settings.MEM_INIT_METHOD = 1
        else:
          assert shared.Settings.MEM_INIT_METHOD != 1
  
        if embed_memfile(options):
          shared.Settings.SUPPORT_BASE64_EMBEDDING = 1
  
        final = do_emscripten(final, target + '.mem', js_libraries)
        save_intermediate('original')
  
        if shared.Settings.WASM_BACKEND:
          # we also received wast and wasm at this stage
          temp_basename = unsuffixed(final)
          wasm_temp = temp_basename + '.wasm'
          shutil.move(wasm_temp, wasm_binary_target)
          if use_source_map(options):
            shutil.move(wasm_temp + '.map', wasm_source_map_target)
  
        if shared.Settings.CYBERDWARF:
          cd_target = final + '.cd'
          shutil.move(cd_target, target + '.cd')
  
      # exit block 'emscript'
      log_time('emscript (llvm => executable code)')
  
      with ToolchainProfiler.profile_block('source transforms'):
        # Embed and preload files
        if len(options.preload_files) or len(options.embed_files):
  
          # Also, MEMFS is not aware of heap resizing feature in wasm, so if MEMFS and memory growth are used together, force
          # no_heap_copy to be enabled.
          if shared.Settings.ALLOW_MEMORY_GROWTH and not options.no_heap_copy:
            logger.info('Enabling --no-heap-copy because -s ALLOW_MEMORY_GROWTH=1 is being used with file_packager.py (pass --no-heap-copy to suppress this notification)')
            options.no_heap_copy = True
  
          logger.debug('setting up files')
          file_args = ['--from-emcc', '--export-name=' + shared.Settings.EXPORT_NAME]
          if len(options.preload_files):
            file_args.append('--preload')
            file_args += options.preload_files
          if len(options.embed_files):
            file_args.append('--embed')
            file_args += options.embed_files
          if len(options.exclude_files):
            file_args.append('--exclude')
            file_args += options.exclude_files
          if options.use_preload_cache:
            file_args.append('--use-preload-cache')
          if options.no_heap_copy:
            file_args.append('--no-heap-copy')
          if shared.Settings.LZ4:
            file_args.append('--lz4')
          if options.use_preload_plugins:
            file_args.append('--use-preload-plugins')
          file_code = run_process([shared.PYTHON, shared.FILE_PACKAGER, unsuffixed(target) + '.data'] + file_args, stdout=PIPE).stdout
          options.pre_js = file_code + options.pre_js
  
        # Apply pre and postjs files
        if options.pre_js or options.post_js:
          logger.debug('applying pre/postjses')
          src = open(final).read()
          final += '.pp.js'
          if WINDOWS: # Avoid duplicating \r\n to \r\r\n when writing out.
            if options.pre_js:
              options.pre_js = options.pre_js.replace('\r\n', '\n')
            if options.post_js:
              options.post_js = options.post_js.replace('\r\n', '\n')
          with open(final, 'w') as f:
            # pre-js code goes right after the Module integration code (so it
            # can use Module), we have a marker for it
            f.write(src.replace('// {{PRE_JSES}}', options.pre_js))
            f.write(options.post_js)
          options.pre_js = src = options.post_js = None
          save_intermediate('pre-post')
  
        # Apply a source code transformation, if requested
        if options.js_transform:
          shutil.copyfile(final, final + '.tr.js')
          final += '.tr.js'
          posix = not shared.WINDOWS
          logger.debug('applying transform: %s', options.js_transform)
          shared.check_call(shared.Building.remove_quotes(shlex.split(options.js_transform, posix=posix) + [os.path.abspath(final)]))
          save_intermediate('transformed')
  
        js_transform_tempfiles = [final]
  
      # exit block 'source transforms'
      log_time('source transforms')
  
      with ToolchainProfiler.profile_block('memory initializer'):
        memfile = None
        if (not shared.Settings.WASM_BACKEND and (shared.Settings.MEM_INIT_METHOD > 0 or embed_memfile(options))) or \
           (shared.Settings.WASM_BACKEND and not shared.Settings.MEM_INIT_IN_WASM):
          if shared.Settings.MINIMAL_RUNTIME:
            # Independent of whether user is doing -o a.html or -o a.js, generate the mem init file as a.mem (and not as a.html.mem or a.js.mem)
            memfile = target.replace('.html', '.mem').replace('.js', '.mem')
          else:
            memfile = target + '.mem'
  
        if memfile:
          if shared.Settings.WASM_BACKEND:
            # For the wasm backend, we don't have any memory info in JS. All we need to do
            # is set the memory initializer url.
            src = open(final).read()
            src = src.replace('var memoryInitializer = null;', 'var memoryInitializer = "%s";' % os.path.basename(memfile))
            open(final + '.mem.js', 'w').write(src)
            final += '.mem.js'
          else:
            # Non-wasm backend path: Strip the memory initializer out of the asmjs file
            shared.try_delete(memfile)
  
            def repl(m):
              # handle chunking of the memory initializer
              s = m.group(1)
              if len(s) == 0:
                return '' # don't emit 0-size ones
              membytes = [int(x or '0') for x in s.split(',')]
              while membytes and membytes[-1] == 0:
                membytes.pop()
              if not membytes:
                return ''
              if shared.Settings.MEM_INIT_METHOD == 2:
                # memory initializer in a string literal
                return "memoryInitializer = '%s';" % shared.JS.generate_string_initializer(membytes)
              open(memfile, 'wb').write(bytearray(membytes))
              if DEBUG:
                # Copy into temp dir as well, so can be run there too
                shared.safe_copy(memfile, os.path.join(shared.get_emscripten_temp_dir(), os.path.basename(memfile)))
              if not shared.Settings.WASM or not shared.Settings.MEM_INIT_IN_WASM:
                return 'memoryInitializer = "%s";' % shared.JS.get_subresource_location(memfile, embed_memfile(options))
              else:
                return ''
  
            src = re.sub(shared.JS.memory_initializer_pattern, repl, open(final).read(), count=1)
            open(final + '.mem.js', 'w').write(src)
            final += '.mem.js'
            src = None
            js_transform_tempfiles[-1] = final # simple text substitution preserves comment line number mappings
            if os.path.exists(memfile):
              save_intermediate('meminit')
              logger.debug('wrote memory initialization to %s', memfile)
            else:
              logger.debug('did not see memory initialization')
  
        if shared.Settings.USE_PTHREADS:
          target_dir = os.path.dirname(os.path.abspath(target))
          worker_output = os.path.join(target_dir, shared.Settings.PTHREAD_WORKER_FILE)
          with open(worker_output, 'w') as f:
            f.write(shared.read_and_preprocess(shared.path_from_root('src', 'worker.js'), expand_macros=True))
  
        # Generate the fetch.js worker script for multithreaded emscripten_fetch() support if targeting pthreads.
        if shared.Settings.USE_FETCH_WORKER:
          shared.make_fetch_worker(final, shared.Settings.FETCH_WORKER_FILE)
  
      # exit block 'memory initializer'
      log_time('memory initializer')
  
      optimizer = JSOptimizer(
        target=target,
        options=options,
        js_transform_tempfiles=js_transform_tempfiles,
        in_temp=in_temp,
      )
      with ToolchainProfiler.profile_block('js opts'):
        # It is useful to run several js optimizer passes together, to save on unneeded unparsing/reparsing
        if shared.Settings.DEAD_FUNCTIONS:
          optimizer.queue += ['eliminateDeadFuncs']
          optimizer.extra_info['dead_functions'] = shared.Settings.DEAD_FUNCTIONS
  
        if options.opt_level >= 1 and options.js_opts:
          logger.debug('running js post-opts')
  
          if DEBUG == 2:
            # Clean up the syntax a bit
            optimizer.queue += ['noop']
  
          def get_eliminate():
            if shared.Settings.ALLOW_MEMORY_GROWTH:
              return 'eliminateMemSafe'
            else:
              return 'eliminate'
  
          if options.opt_level >= 2:
            optimizer.queue += [get_eliminate()]
  
            if shared.Settings.AGGRESSIVE_VARIABLE_ELIMINATION:
              # note that this happens before registerize/minification, which can obfuscate the name of 'label', which is tricky
              optimizer.queue += ['aggressiveVariableElimination']
  
            optimizer.queue += ['simplifyExpressions']
  
            if shared.Settings.EMTERPRETIFY:
              # emterpreter code will not run through a JS optimizing JIT, do more work ourselves
              optimizer.queue += ['localCSE']
  
        if shared.Settings.EMTERPRETIFY:
          # add explicit label setting, as we will run aggressiveVariableElimination late, *after* 'label' is no longer notable by name
          optimizer.queue += ['safeLabelSetting']
  
        if options.opt_level >= 1 and options.js_opts:
          if options.opt_level >= 2:
            # simplify ifs if it is ok to make the code somewhat unreadable,
            # with commaified code breaks late aggressive variable elimination)
            # do not do this with binaryen, as commaifying confuses binaryen call type detection (FIXME, in theory, but unimportant)
            debugging = options.debug_level == 0 or options.profiling
            if shared.Settings.SIMPLIFY_IFS and debugging and not shared.Settings.WASM:
              optimizer.queue += ['simplifyIfs']
  
            if shared.Settings.PRECISE_F32:
              optimizer.queue += ['optimizeFrounds']
  
        if options.js_opts:
          if shared.Settings.SAFE_HEAP and not shared.Building.is_wasm_only():
            optimizer.queue += ['safeHeap']
  
          if options.opt_level >= 2 and options.debug_level < 3:
            if options.opt_level >= 3 or options.shrink_level > 0:
              optimizer.queue += ['registerizeHarder']
            else:
              optimizer.queue += ['registerize']
  
          # NOTE: Important that this comes after registerize/registerizeHarder
          if shared.Settings.ELIMINATE_DUPLICATE_FUNCTIONS and options.opt_level >= 2:
            optimizer.flush()
            shared.Building.eliminate_duplicate_funcs(final)
            save_intermediate('dfe')
  
        if shared.Settings.EVAL_CTORS and options.memory_init_file and not use_source_map(options) and not shared.Settings.WASM:
          optimizer.flush()
          shared.Building.eval_ctors(final, memfile)
          save_intermediate('eval-ctors')
  
        if options.js_opts:
          # some compilation modes require us to minify later or not at all
          if not shared.Settings.EMTERPRETIFY and not shared.Settings.WASM:
            optimizer.do_minify()
  
          if options.opt_level >= 2:
            optimizer.queue += ['asmLastOpts']
  
          if shared.Settings.FINALIZE_ASM_JS:
            optimizer.queue += ['last']
  
          optimizer.flush()
  
        if options.use_closure_compiler == 2 and not shared.Settings.WASM_BACKEND:
          optimizer.flush()
  
          logger.debug('running closure')
          # no need to add this to js_transform_tempfiles, because closure and
          # debug_level > 0 are never simultaneously true
          final = shared.Building.closure_compiler(final, pretty=options.debug_level >= 1,
                                                   extra_closure_args=options.closure_args)
          save_intermediate('closure')
  
      log_time('js opts')
  
      with ToolchainProfiler.profile_block('final emitting'):
        if shared.Settings.EMTERPRETIFY:
          emterpretify(js_target, optimizer, options)
  
        # Remove some trivial whitespace
        # TODO: do not run when compress has already been done on all parts of the code
        # src = open(final).read()
        # src = re.sub(r'\n+[ \n]*\n+', '\n', src)
        # open(final, 'w').write(src)
  
        # Bundle symbol data in with the cyberdwarf file
        if shared.Settings.CYBERDWARF:
          run_process([shared.PYTHON, shared.path_from_root('tools', 'emdebug_cd_merger.py'), target + '.cd', target + '.symbols'])
  
        if use_source_map(options) and not shared.Settings.WASM:
          emit_js_source_maps(target, optimizer.js_transform_tempfiles)
  
        # track files that will need native eols
        generated_text_files_with_native_eols = []
  
        if (options.separate_asm or shared.Settings.WASM) and not shared.Settings.WASM_BACKEND:
          separate_asm_js(final, asm_target)
          generated_text_files_with_native_eols += [asm_target]
  
        if shared.Settings.WASM:
          do_binaryen(target, asm_target, options, memfile, wasm_binary_target,
                      wasm_text_target, wasm_source_map_target, misc_temp_files,
                      optimizer)
  
        if shared.Settings.MODULARIZE:
          modularize()
  
        module_export_name_substitution()
  
        # Run a final regex pass to clean up items that were not possible to optimize by Closure, or unoptimalities that were left behind
        # by processing steps that occurred after Closure.
        if shared.Settings.MINIMAL_RUNTIME == 2 and shared.Settings.USE_CLOSURE_COMPILER and options.debug_level == 0:
          # Process .js runtime file
          shared.run_process([shared.PYTHON, shared.path_from_root('tools', 'hacky_postprocess_around_closure_limitations.py'), final])
          # Process .asm.js file
          if not shared.Settings.WASM:
            shared.run_process([shared.PYTHON, shared.path_from_root('tools', 'hacky_postprocess_around_closure_limitations.py'), asm_target])
  
        # The JS is now final. Move it to its final location
        shutil.move(final, js_target)
  
        generated_text_files_with_native_eols += [js_target]
  
        # If we were asked to also generate HTML, do that
        if final_suffix == '.html':
          generate_html(target, options, js_target, target_basename,
                        asm_target, wasm_binary_target,
                        memfile, optimizer)
        else:
          if options.proxy_to_worker:
            generate_worker_js(target, js_target, target_basename)
  
        if embed_memfile(options) and memfile:
          shared.try_delete(memfile)
  
        for f in generated_text_files_with_native_eols:
          tools.line_endings.convert_line_endings_in_file(f, os.linesep, options.output_eol)
      log_time('final emitting')
      # exit block 'final emitting'
  
    finally:
      if DEBUG:
        shared.Cache.release_cache_lock()
  
    if DEBUG:
      logger.debug('total time: %.2f seconds', (time.time() - start_time))
  
    return 0
  
  
  def parse_args(newargs):
    options = EmccOptions()
    settings_changes = []
    should_exit = False
  
    def check_bad_eq(arg):
      if '=' in arg:
        exit_with_error('Invalid parameter (do not use "=" with "--" options)')
  
    for i in range(len(newargs)):
      # On Windows Vista (and possibly others), excessive spaces in the command line
      # leak into the items in this array, so trim e.g. 'foo.cpp ' -> 'foo.cpp'
      newargs[i] = newargs[i].strip()
      if newargs[i].startswith('-O'):
        # Let -O default to -O2, which is what gcc does.
        options.requested_level = newargs[i][2:] or '2'
        if options.requested_level == 's':
          options.llvm_opts = ['-Os']
          options.requested_level = 2
          options.shrink_level = 1
          settings_changes.append('INLINING_LIMIT=50')
        elif options.requested_level == 'z':
          options.llvm_opts = ['-Oz']
          options.requested_level = 2
          options.shrink_level = 2
          settings_changes.append('INLINING_LIMIT=25')
        options.opt_level = validate_arg_level(options.requested_level, 3, 'Invalid optimization level: ' + newargs[i], clamp=True)
      elif newargs[i].startswith('--js-opts'):
        check_bad_eq(newargs[i])
        options.js_opts = int(newargs[i + 1])
        if options.js_opts:
          options.force_js_opts = True
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--llvm-opts'):
        check_bad_eq(newargs[i])
        options.llvm_opts = parse_value(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--llvm-lto'):
        check_bad_eq(newargs[i])
        options.llvm_lto = int(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--closure-args'):
        check_bad_eq(newargs[i])
        args = newargs[i + 1]
        options.closure_args += shlex.split(args)
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--closure'):
        check_bad_eq(newargs[i])
        options.use_closure_compiler = int(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--js-transform'):
        check_bad_eq(newargs[i])
        options.js_transform = newargs[i + 1]
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--pre-js'):
        check_bad_eq(newargs[i])
        options.pre_js += open(newargs[i + 1]).read() + '\n'
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--post-js'):
        check_bad_eq(newargs[i])
        options.post_js += open(newargs[i + 1]).read() + '\n'
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--minify'):
        check_bad_eq(newargs[i])
        assert newargs[i + 1] == '0', '0 is the only supported option for --minify; 1 has been deprecated'
        options.debug_level = max(1, options.debug_level)
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('-g'):
        requested_level = newargs[i][2:] or '3'
        options.debug_level = validate_arg_level(requested_level, 4, 'Invalid debug level: ' + newargs[i])
        options.requested_debug = newargs[i]
        newargs[i] = ''
      elif newargs[i] == '-profiling' or newargs[i] == '--profiling':
        options.debug_level = max(options.debug_level, 2)
        options.profiling = True
        newargs[i] = ''
      elif newargs[i] == '-profiling-funcs' or newargs[i] == '--profiling-funcs':
        options.profiling_funcs = True
        newargs[i] = ''
      elif newargs[i] == '--tracing' or newargs[i] == '--memoryprofiler':
        if newargs[i] == '--memoryprofiler':
          options.memory_profiler = True
        options.tracing = True
        newargs[i] = ''
        newargs.append('-D__EMSCRIPTEN_TRACING__=1')
        settings_changes.append("EMSCRIPTEN_TRACING=1")
        options.js_libraries.append(shared.path_from_root('src', 'library_trace.js'))
      elif newargs[i] == '--emit-symbol-map':
        options.emit_symbol_map = True
        shared.Settings.EMIT_SYMBOL_MAP = 1
        newargs[i] = ''
      elif newargs[i] == '--bind':
        shared.Settings.EMBIND = 1
        newargs[i] = ''
        options.js_libraries.append(shared.path_from_root('src', 'embind', 'emval.js'))
        options.js_libraries.append(shared.path_from_root('src', 'embind', 'embind.js'))
        if options.default_cxx_std:
          # Force C++11 for embind code, but only if user has not explicitly overridden a standard.
          options.default_cxx_std = '-std=c++11'
      elif newargs[i].startswith('-std=') or newargs[i].startswith('--std='):
        # User specified a standard to use, clear Emscripten from specifying it.
        options.default_cxx_std = None
      elif newargs[i].startswith('--embed-file'):
        check_bad_eq(newargs[i])
        options.embed_files.append(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--preload-file'):
        check_bad_eq(newargs[i])
        options.preload_files.append(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--exclude-file'):
        check_bad_eq(newargs[i])
        options.exclude_files.append(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--use-preload-cache'):
        options.use_preload_cache = True
        newargs[i] = ''
      elif newargs[i].startswith('--no-heap-copy'):
        options.no_heap_copy = True
        newargs[i] = ''
      elif newargs[i].startswith('--use-preload-plugins'):
        options.use_preload_plugins = True
        newargs[i] = ''
      elif newargs[i] == '--ignore-dynamic-linking':
        options.ignore_dynamic_linking = True
        newargs[i] = ''
      elif newargs[i] == '-v':
        shared.PRINT_STAGES = True
        shared.check_sanity(force=True)
      elif newargs[i].startswith('--shell-file'):
        check_bad_eq(newargs[i])
        options.shell_path = newargs[i + 1]
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--source-map-base'):
        check_bad_eq(newargs[i])
        options.source_map_base = newargs[i + 1]
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i].startswith('--js-library'):
        check_bad_eq(newargs[i])
        options.js_libraries.append(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i] == '--remove-duplicates':
        logger.warning('--remove-duplicates is deprecated as it is no longer needed. If you cannot link without it, file a bug with a testcase')
        newargs[i] = ''
      elif newargs[i] == '--jcache':
        logger.error('jcache is no longer supported')
        newargs[i] = ''
      elif newargs[i] == '--cache':
        check_bad_eq(newargs[i])
        os.environ['EM_CACHE'] = os.path.normpath(newargs[i + 1])
        shared.reconfigure_cache()
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i] == '--clear-cache':
        logger.info('clearing cache as requested by --clear-cache')
        shared.Cache.erase()
        shared.check_sanity(force=True) # this is a good time for a sanity check
        should_exit = True
      elif newargs[i] == '--clear-ports':
        logger.info('clearing ports and cache as requested by --clear-ports')
        system_libs.Ports.erase()
        shared.Cache.erase()
        shared.check_sanity(force=True) # this is a good time for a sanity check
        should_exit = True
      elif newargs[i] == '--show-ports':
        system_libs.show_ports()
        should_exit = True
      elif newargs[i] == '--save-bc':
        check_bad_eq(newargs[i])
        options.save_bc = newargs[i + 1]
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i] == '--memory-init-file':
        check_bad_eq(newargs[i])
        options.memory_init_file = int(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i] == '--proxy-to-worker':
        options.proxy_to_worker = True
        newargs[i] = ''
      elif newargs[i] == '--valid-abspath':
        options.valid_abspaths.append(newargs[i + 1])
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i] == '--separate-asm':
        options.separate_asm = True
        newargs[i] = ''
      elif newargs[i].startswith(('-I', '-L')):
        options.path_name = newargs[i][2:]
        if os.path.isabs(options.path_name) and not is_valid_abspath(options, options.path_name):
          # Of course an absolute path to a non-system-specific library or header
          # is fine, and you can ignore this warning. The danger are system headers
          # that are e.g. x86 specific and nonportable. The emscripten bundled
          # headers are modified to be portable, local system ones are generally not.
          shared.WarningManager.warn(
              'ABSOLUTE_PATHS', '-I or -L of an absolute path "' + newargs[i] +
              '" encountered. If this is to a local system header/library, it may '
              'cause problems (local system files make sense for compiling natively '
              'on your system, but not necessarily to JavaScript).')
      elif newargs[i] == '--emrun':
        options.emrun = True
        newargs[i] = ''
      elif newargs[i] == '--cpuprofiler':
        options.cpu_profiler = True
        newargs[i] = ''
      elif newargs[i] == '--threadprofiler':
        options.thread_profiler = True
        settings_changes.append('PTHREADS_PROFILING=1')
        newargs[i] = ''
      elif newargs[i] == '-fno-exceptions':
        settings_changes.append('DISABLE_EXCEPTION_THROWING=1')
      elif newargs[i] == '-fexceptions':
        settings_changes.append('DISABLE_EXCEPTION_THROWING=0')
      elif newargs[i] == '--default-obj-ext':
        newargs[i] = ''
        options.default_object_extension = newargs[i + 1]
        if not options.default_object_extension.startswith('.'):
          options.default_object_extension = '.' + options.default_object_extension
        newargs[i + 1] = ''
      elif newargs[i].startswith("-fsanitize=cfi"):
        options.cfi = True
      elif newargs[i] == "--output_eol":
        if newargs[i + 1].lower() == 'windows':
          options.output_eol = '\r\n'
        elif newargs[i + 1].lower() == 'linux':
          options.output_eol = '\n'
        else:
          exit_with_error('Invalid value "' + newargs[i + 1] + '" to --output_eol!')
        newargs[i] = ''
        newargs[i + 1] = ''
      elif newargs[i] == '--generate-config':
        optarg = newargs[i + 1]
        path = os.path.expanduser(optarg)
        if os.path.exists(path):
          exit_with_error('File ' + optarg + ' passed to --generate-config already exists!')
        else:
          shared.generate_config(optarg)
        should_exit = True
      # Record SIMD setting because it controls whether the autovectorizer runs
      elif newargs[i] == '-msimd128':
        settings_changes.append('SIMD=1')
      elif newargs[i] == '-mno-simd128':
        settings_changes.append('SIMD=0')
      # Record USE_PTHREADS setting because it controls whether --shared-memory is passed to lld
      elif newargs[i] == '-pthread':
        settings_changes.append('USE_PTHREADS=1')
      elif newargs[i] in ('-fno-diagnostics-color', '-fdiagnostics-color=never'):
        colored_logger.disable()
      elif newargs[i] == '-no-canonical-prefixes':
        options.expand_symlinks = False
  
    if should_exit:
      sys.exit(0)
  
    newargs = [arg for arg in newargs if arg]
    return options, settings_changes, newargs
  
  
  def emterpretify(js_target, optimizer, options):
    global final
    optimizer.flush('pre-emterpretify')
    logger.debug('emterpretifying')
    blacklist = shared.Settings.EMTERPRETIFY_BLACKLIST
    whitelist = shared.Settings.EMTERPRETIFY_WHITELIST
    synclist = shared.Settings.EMTERPRETIFY_SYNCLIST
    if type(blacklist) == list:
      blacklist = json.dumps(blacklist)
    if type(whitelist) == list:
      whitelist = json.dumps(whitelist)
    if type(synclist) == list:
      synclist = json.dumps(synclist)
  
    args = [shared.PYTHON,
            shared.path_from_root('tools', 'emterpretify.py'),
            js_target,
            final + '.em.js',
            blacklist,
            whitelist,
            synclist,
            str(shared.Settings.SWAPPABLE_ASM_MODULE)]
    if shared.Settings.EMTERPRETIFY_ASYNC:
      args += ['ASYNC=1']
    if shared.Settings.EMTERPRETIFY_ADVISE:
      args += ['ADVISE=1']
    if options.profiling or options.profiling_funcs:
      args += ['PROFILING=1']
    if shared.Settings.ASSERTIONS:
      args += ['ASSERTIONS=1']
    if shared.Settings.PRECISE_F32:
      args += ['FROUND=1']
    if shared.Settings.ALLOW_MEMORY_GROWTH:
      args += ['MEMORY_SAFE=1']
    if shared.Settings.EMTERPRETIFY_FILE:
      args += ['FILE="' + shared.Settings.EMTERPRETIFY_FILE + '"']
  
    try:
      # move temp js to final position, alongside its mem init file
      shutil.move(final, js_target)
      shared.check_call(args)
    finally:
      shared.try_delete(js_target)
  
    final = final + '.em.js'
  
    if shared.Settings.EMTERPRETIFY_ADVISE:
      logger.warning('halting compilation due to EMTERPRETIFY_ADVISE')
      sys.exit(0)
  
    # minify (if requested) after emterpreter processing, and finalize output
    logger.debug('finalizing emterpreted code')
    shared.Settings.FINALIZE_ASM_JS = 1
    if not shared.Settings.WASM:
      optimizer.do_minify()
    optimizer.queue += ['last']
    optimizer.flush('finalizing-emterpreted-code')
  
    # finalize the original as well, if we will be swapping it in (TODO: add specific option for this)
    if shared.Settings.SWAPPABLE_ASM_MODULE:
      real = final
      original = js_target + '.orig.js' # the emterpretify tool saves the original here
      final = original
      logger.debug('finalizing original (non-emterpreted) code at ' + final)
      if not shared.Settings.WASM:
        optimizer.do_minify()
      optimizer.queue += ['last']
      optimizer.flush('finalizing-original-code')
      safe_copy(final, original)
      final = real
  
  
  def emit_js_source_maps(target, js_transform_tempfiles):
    logger.debug('generating source maps')
    jsrun.run_js_tool(shared.path_from_root('tools', 'source-maps', 'sourcemapper.js'),
                      shared.NODE_JS, js_transform_tempfiles +
                      ['--sourceRoot', os.getcwd(),
                       '--mapFileBaseName', target,
                       '--offset', '0'])
  
  
  def separate_asm_js(final, asm_target):
    """Separate out the asm.js code, if asked. Or, if necessary for another option"""
    logger.debug('separating asm')
    shared.check_call([shared.PYTHON, shared.path_from_root('tools', 'separate_asm.py'), final, asm_target, final, shared.Settings.SEPARATE_ASM_MODULE_NAME])
  
  
  def do_binaryen(target, asm_target, options, memfile, wasm_binary_target,
                  wasm_text_target, wasm_source_map_target, misc_temp_files,
                  optimizer):
    global final
    logger.debug('using binaryen')
    binaryen_bin = shared.Building.get_binaryen_bin()
    # whether we need to emit -g (function name debug info) in the final wasm
    debug_info = options.debug_level >= 2 or options.profiling_funcs
    # whether we need to emit -g in the intermediate binaryen invocations (but not necessarily at the very end).
    # this is necessary for emitting a symbol map at the end.
    intermediate_debug_info = bool(debug_info or options.emit_symbol_map or shared.Settings.ASYNCIFY_WHITELIST or shared.Settings.ASYNCIFY_BLACKLIST)
    emit_symbol_map = options.emit_symbol_map or shared.Settings.CYBERDWARF
    # finish compiling to WebAssembly, using asm2wasm, if we didn't already emit WebAssembly directly using the wasm backend.
    if not shared.Settings.WASM_BACKEND:
      if DEBUG:
        # save the asm.js input
        shared.safe_copy(asm_target, os.path.join(shared.get_emscripten_temp_dir(), os.path.basename(asm_target)))
      cmd = [os.path.join(binaryen_bin, 'asm2wasm'), asm_target, '--total-memory=' + str(shared.Settings.TOTAL_MEMORY)]
      if shared.Settings.BINARYEN_TRAP_MODE not in ('js', 'clamp', 'allow'):
        exit_with_error('invalid BINARYEN_TRAP_MODE value: ' + shared.Settings.BINARYEN_TRAP_MODE + ' (should be js/clamp/allow)')
      cmd += ['--trap-mode=' + shared.Settings.BINARYEN_TRAP_MODE]
      if shared.Settings.BINARYEN_IGNORE_IMPLICIT_TRAPS:
        cmd += ['--ignore-implicit-traps']
      # pass optimization level to asm2wasm (if not optimizing, or which passes we should run was overridden, do not optimize)
      if options.opt_level > 0:
        cmd.append(shared.Building.opt_level_to_str(options.opt_level, options.shrink_level))
      # import mem init file if it exists, and if we will not be using asm.js as a binaryen method (as it needs the mem init file, of course)
      mem_file_exists = options.memory_init_file and os.path.exists(memfile)
      import_mem_init = mem_file_exists and shared.Settings.MEM_INIT_IN_WASM
      if import_mem_init:
        cmd += ['--mem-init=' + memfile]
        if not shared.Settings.RELOCATABLE:
          cmd += ['--mem-base=' + str(shared.Settings.GLOBAL_BASE)]
      # various options imply that the imported table may not be the exact size as
      # the wasm module's own table segments
      if shared.Settings.RELOCATABLE or shared.Settings.RESERVED_FUNCTION_POINTERS > 0 or shared.Settings.EMULATED_FUNCTION_POINTERS:
        cmd += ['--table-max=-1']
      if shared.Settings.SIDE_MODULE:
        cmd += ['--mem-max=-1']
      elif shared.Settings.WASM_MEM_MAX >= 0:
        cmd += ['--mem-max=' + str(shared.Settings.WASM_MEM_MAX)]
      if shared.Settings.LEGALIZE_JS_FFI != 1:
        cmd += ['--no-legalize-javascript-ffi']
      if shared.Building.is_wasm_only():
        cmd += ['--wasm-only'] # this asm.js is code not intended to run as asm.js, it is only ever going to be wasm, an can contain special fastcomp-wasm support
      if shared.Settings.USE_PTHREADS:
        cmd += ['--enable-threads']
      if intermediate_debug_info:
        cmd += ['-g']
      if emit_symbol_map:
        cmd += ['--symbolmap=' + target + '.symbols']
      # we prefer to emit a binary, as it is more efficient. however, when we
      # want full debug info support (not just function names), then we must
      # emit text (at least until wasm gains support for debug info in binaries)
      target_binary = options.debug_level < 3
      if target_binary:
        cmd += ['-o', wasm_binary_target]
      else:
        cmd += ['-o', wasm_text_target, '-S']
      cmd += shared.Building.get_binaryen_feature_flags()
      logger.debug('asm2wasm (asm.js => WebAssembly): ' + ' '.join(cmd))
      TimeLogger.update()
      shared.check_call(cmd)
  
      if not target_binary:
        cmd = [os.path.join(binaryen_bin, 'wasm-as'), wasm_text_target, '-o', wasm_binary_target, '--all-features', '--disable-bulk-memory']
        if intermediate_debug_info:
          cmd += ['-g']
          if use_source_map(options):
            cmd += ['--source-map=' + wasm_source_map_target]
            cmd += ['--source-map-url=' + options.source_map_base + os.path.basename(wasm_binary_target) + '.map']
        logger.debug('wasm-as (text => binary): ' + ' '.join(cmd))
        shared.check_call(cmd)
      if import_mem_init:
        # remove the mem init file in later processing; it does not need to be prefetched in the html, etc.
        if DEBUG:
          safe_move(memfile, os.path.join(shared.get_emscripten_temp_dir(), os.path.basename(memfile)))
        else:
          os.unlink(memfile)
      log_time('asm2wasm')
    if options.binaryen_passes:
      if '--post-emscripten' in options.binaryen_passes:
        # the value of the sbrk pointer has been computed by the JS compiler, and we can apply it in the wasm
        # (we can't add this value when we placed post-emscripten in the proper position in the list of
        # passes because that was before the value was computed)
        options.binaryen_passes += ['--pass-arg=emscripten-sbrk-ptr@%d' % shared.Settings.DYNAMICTOP_PTR]
        if shared.Settings.STANDALONE_WASM:
          options.binaryen_passes += ['--pass-arg=emscripten-sbrk-val@%d' % shared.Settings.DYNAMIC_BASE]
      if DEBUG:
        shared.safe_copy(wasm_binary_target, os.path.join(shared.get_emscripten_temp_dir(), os.path.basename(wasm_binary_target) + '.pre-byn'))
      cmd = [os.path.join(binaryen_bin, 'wasm-opt'), wasm_binary_target, '-o', wasm_binary_target] + options.binaryen_passes
      cmd += shared.Building.get_binaryen_feature_flags()
      if intermediate_debug_info:
        cmd += ['-g'] # preserve the debug info
      if use_source_map(options):
        cmd += ['--input-source-map=' + wasm_source_map_target]
        cmd += ['--output-source-map=' + wasm_source_map_target]
        cmd += ['--output-source-map-url=' + options.source_map_base + os.path.basename(wasm_binary_target) + '.map']
        if DEBUG:
          shared.safe_copy(wasm_source_map_target, os.path.join(shared.get_emscripten_temp_dir(), os.path.basename(wasm_source_map_target) + '.pre-byn'))
      logger.debug('wasm-opt on binaryen passes: %s', cmd)
      shared.print_compiler_stage(cmd)
      shared.check_call(cmd)
    if shared.Settings.BINARYEN_SCRIPTS:
      binaryen_scripts = os.path.join(shared.BINARYEN_ROOT, 'scripts')
      script_env = os.environ.copy()
      root_dir = os.path.abspath(os.path.dirname(__file__))
      if script_env.get('PYTHONPATH'):
        script_env['PYTHONPATH'] += ':' + root_dir
      else:
        script_env['PYTHONPATH'] = root_dir
      for script in shared.Settings.BINARYEN_SCRIPTS.split(','):
        logger.debug('running binaryen script: ' + script)
        shared.check_call([shared.PYTHON, os.path.join(binaryen_scripts, script), final, wasm_text_target], env=script_env)
    if shared.Settings.EVAL_CTORS:
      if DEBUG:
        save_intermediate_with_wasm('pre-eval-ctors', wasm_binary_target)
      shared.Building.eval_ctors(final, wasm_binary_target, binaryen_bin, debug_info=intermediate_debug_info)
  
    # after generating the wasm, do some final operations
    if shared.Settings.SIDE_MODULE and not shared.Settings.WASM_BACKEND:
      wso = shared.WebAssembly.make_shared_library(final, wasm_binary_target, shared.Settings.RUNTIME_LINKED_LIBS)
      # replace the wasm binary output with the dynamic library.
      # TODO: use a specific suffix for such files?
      shutil.move(wso, wasm_binary_target)
      if not DEBUG:
        os.unlink(asm_target) # we don't need the asm.js, it can just confuse
  
    # after generating the wasm, do some final operations
    if shared.Settings.EMIT_EMSCRIPTEN_METADATA:
      shared.WebAssembly.add_emscripten_metadata(final, wasm_binary_target)
  
    if shared.Settings.SIDE_MODULE:
      sys.exit(0) # and we are done.
  
    # pthreads memory growth requires some additional JS fixups
    if shared.Settings.USE_PTHREADS and shared.Settings.ALLOW_MEMORY_GROWTH:
      final = shared.Building.apply_wasm_memory_growth(final)
  
    if options.opt_level >= 2 and options.debug_level <= 2:
      # minify the JS
      optimizer.do_minify() # calculate how to minify
      save_intermediate_with_wasm('preclean', wasm_binary_target)
      final = shared.Building.minify_wasm_js(js_file=final,
                                             wasm_file=wasm_binary_target,
                                             expensive_optimizations=will_metadce(options),
                                             minify_whitespace=optimizer.minify_whitespace,
                                             debug_info=intermediate_debug_info,
                                             emitting_js=not target.endswith(WASM_ENDINGS))
      save_intermediate_with_wasm('postclean', wasm_binary_target)
  
    def run_closure_compiler(final):
      final = shared.Building.closure_compiler(final, pretty=not optimizer.minify_whitespace,
                                               extra_closure_args=options.closure_args)
      save_intermediate_with_wasm('closure', wasm_binary_target)
      return final
  
    if options.use_closure_compiler:
      final = run_closure_compiler(final)
  
    symbols_file = target + '.symbols' if options.emit_symbol_map else None
  
    if shared.Settings.WASM2JS:
      final = shared.Building.wasm2js(final,
                                      wasm_binary_target,
                                      opt_level=options.opt_level,
                                      minify_whitespace=optimizer.minify_whitespace,
                                      use_closure_compiler=options.use_closure_compiler,
                                      debug_info=intermediate_debug_info,
                                      symbols_file=symbols_file)
      save_intermediate('wasm2js')
  
      shared.try_delete(wasm_binary_target)
  
    # emit the final symbols, either in the binary or in a symbol map.
    # this will also remove debug info if we only kept it around in the intermediate invocations.
    # note that wasm2js handles the symbol map itself (as it manipulates and then
    # replaces the wasm with js)
    if intermediate_debug_info and not shared.Settings.WASM2JS:
      shared.Building.handle_final_wasm_symbols(wasm_file=wasm_binary_target, symbols_file=symbols_file, debug_info=debug_info)
      save_intermediate_with_wasm('symbolmap', wasm_binary_target)
  
    # replace placeholder strings with correct subresource locations
    if shared.Settings.SINGLE_FILE:
      js = open(final).read()
      for target, replacement_string, should_embed in (
          (wasm_binary_target,
           shared.FilenameReplacementStrings.WASM_BINARY_FILE,
           True),
          (asm_target,
           shared.FilenameReplacementStrings.ASMJS_CODE_FILE,
           False),
        ):
        if should_embed and os.path.isfile(target):
          js = js.replace(replacement_string, shared.JS.get_subresource_location(target))
        else:
          js = js.replace(replacement_string, '')
        shared.try_delete(target)
      with open(final, 'w') as f:
        f.write(js)
  
  
  def modularize():
    global final
    logger.debug('Modularizing, assigning to var ' + shared.Settings.EXPORT_NAME)
    src = open(final).read()
  
    # TODO: exports object generation for MINIMAL_RUNTIME
    exports_object = '{}' if shared.Settings.MINIMAL_RUNTIME else shared.Settings.EXPORT_NAME
  
    src = '''
  function(%(EXPORT_NAME)s) {
    %(EXPORT_NAME)s = %(EXPORT_NAME)s || {};
  
  %(src)s
  
    return %(exports_object)s
  }
  ''' % {
      'EXPORT_NAME': shared.Settings.EXPORT_NAME,
      'src': src,
      'exports_object': exports_object
    }
  
    if not shared.Settings.MODULARIZE_INSTANCE:
      if shared.Settings.MINIMAL_RUNTIME and not shared.Settings.USE_PTHREADS:
        # Single threaded MINIMAL_RUNTIME programs do not need access to
        # document.currentScript, so a simple export declaration is enough.
        src = 'var %s=%s' % (shared.Settings.EXPORT_NAME, src)
      else:
        # When MODULARIZE this JS may be executed later,
        # after document.currentScript is gone, so we save it.
        # (when MODULARIZE_INSTANCE, an instance is created
        # immediately anyhow, like in non-modularize mode)
        # In EXPORT_ES6 + USE_PTHREADS the 'thread' is actually an ES6 module webworker running in strict mode,
        # so doesn't have access to 'document'. In this case use 'import.meta' instead.
        if shared.Settings.EXPORT_ES6 and shared.Settings.USE_ES6_IMPORT_META:
          script_url = "import.meta.url"
        else:
          script_url = "typeof document !== 'undefined' && document.currentScript ? document.currentScript.src : undefined"
        src = '''
  var %(EXPORT_NAME)s = (function() {
    var _scriptDir = %(script_url)s;
    return (%(src)s);
  })();
  ''' % {
          'EXPORT_NAME': shared.Settings.EXPORT_NAME,
          'src': src,
          'script_url': script_url
        }
    else:
      # Create the MODULARIZE_INSTANCE instance
      # Note that we notice the global Module object, just like in normal
      # non-MODULARIZE mode (while MODULARIZE has the user create the instances,
      # and the user can decide whether to use Module there or something
      # else etc.).
      src = '''
  var %(EXPORT_NAME)s = (%(src)s)(typeof %(EXPORT_NAME)s === 'object' ? %(EXPORT_NAME)s : {});
  ''' % {
        'EXPORT_NAME': shared.Settings.EXPORT_NAME,
        'src': src
      }
  
    final = final + '.modular.js'
    with open(final, 'w') as f:
      f.write(src)
  
      # Export using a UMD style export, or ES6 exports if selected
  
      if shared.Settings.EXPORT_ES6:
        f.write('''export default %s;''' % shared.Settings.EXPORT_NAME)
      elif not shared.Settings.MINIMAL_RUNTIME:
        f.write('''if (typeof exports === 'object' && typeof module === 'object')
        module.exports = %(EXPORT_NAME)s;
      else if (typeof define === 'function' && define['amd'])
        define([], function() { return %(EXPORT_NAME)s; });
      else if (typeof exports === 'object')
        exports["%(EXPORT_NAME)s"] = %(EXPORT_NAME)s;
      ''' % {
          'EXPORT_NAME': shared.Settings.EXPORT_NAME
        })
  
    save_intermediate('modularized')
  
  
  def module_export_name_substitution():
    global final
    logger.debug('Private module export name substitution with ' + shared.Settings.EXPORT_NAME)
    src = open(final).read()
    final = final + '.module_export_name_substitution.js'
    if shared.Settings.MINIMAL_RUNTIME:
      # In MINIMAL_RUNTIME the Module object is always present to provide the .asm.js/.wasm content
      replacement = shared.Settings.EXPORT_NAME
    else:
      replacement = "typeof %(EXPORT_NAME)s !== 'undefined' ? %(EXPORT_NAME)s : {}" % {"EXPORT_NAME": shared.Settings.EXPORT_NAME}
    with open(final, 'w') as f:
      src = src.replace(shared.JS.module_export_name_substitution_pattern, replacement)
      # For Node.js and other shell environments, create an unminified Module object so that
      # loading external .asm.js file that assigns to Module['asm'] works even when Closure is used.
      if shared.Settings.MINIMAL_RUNTIME and (shared.Settings.target_environment_may_be('node') or
                                              shared.Settings.target_environment_may_be('shell')):
        src = 'if(typeof Module==="undefined"){var Module={};}' + src
      f.write(src)
    save_intermediate('module_export_name_substitution')
  
  
  def generate_minimal_runtime_html(target, options, js_target, target_basename,
                                    asm_target, wasm_binary_target,
                                    memfile, optimizer):
    logger.debug('generating HTML for minimal runtime')
    shell = read_and_preprocess(options.shell_path)
    if re.search(r'{{{\s*SCRIPT\s*}}}', shell):
      exit_with_error('--shell-file "' + options.shell_path + '": MINIMAL_RUNTIME uses a different kind of HTML page shell file than the traditional runtime! Please see $EMSCRIPTEN/src/shell_minimal_runtime.html for a template to use as a basis.')
  
    shell = shell.replace('{{{ TARGET_BASENAME }}}', target_basename)
    shell = shell.replace('{{{ EXPORT_NAME }}}', shared.Settings.EXPORT_NAME)
    shell = tools.line_endings.convert_line_endings(shell, '\n', options.output_eol)
    with open(target, 'wb') as f:
      f.write(asbytes(shell))
  
  
  def generate_traditional_runtime_html(target, options, js_target, target_basename,
                                        asm_target, wasm_binary_target,
                                        memfile, optimizer):
    script = ScriptSource()
  
    shell = read_and_preprocess(options.shell_path)
    assert '{{{ SCRIPT }}}' in shell, 'HTML shell must contain  {{{ SCRIPT }}}  , see src/shell.html for an example'
    base_js_target = os.path.basename(js_target)
  
    asm_mods = []
  
    if options.proxy_to_worker:
      proxy_worker_filename = (shared.Settings.PROXY_TO_WORKER_FILENAME or target_basename) + '.js'
      worker_js = worker_js_script(proxy_worker_filename)
      script.inline = ('''
    var filename = '%s';
    if ((',' + window.location.search.substr(1) + ',').indexOf(',noProxy,') < 0) {
      console.log('running code in a web worker');
  ''' % shared.JS.get_subresource_location(proxy_worker_filename)) + worker_js + '''
    } else {
      // note: no support for code mods (PRECISE_F32==2)
      console.log('running code on the main thread');
      var fileBytes = tryParseAsDataURI(filename);
      var script = document.createElement('script');
      if (fileBytes) {
        script.innerHTML = intArrayToString(fileBytes);
      } else {
        script.src = filename;
      }
      document.body.appendChild(script);
    }
  '''
    else:
      # Normal code generation path
      script.src = base_js_target
  
      asm_mods = client_mods.get_mods(shared.Settings,
                                      minified='minifyNames' in optimizer.queue_history,
                                      separate_asm=options.separate_asm)
  
    if not shared.Settings.SINGLE_FILE:
      if shared.Settings.EMTERPRETIFY_FILE:
        # We need to load the emterpreter file before anything else, it has to be synchronously ready
        script.un_src()
        script.inline = '''
            var emterpretURL = '%s';
            var emterpretXHR = new XMLHttpRequest();
            emterpretXHR.open('GET', emterpretURL, true);
            emterpretXHR.responseType = 'arraybuffer';
            emterpretXHR.onload = function() {
              if (emterpretXHR.status === 200 || emterpretXHR.status === 0) {
                Module.emterpreterFile = emterpretXHR.response;
              } else {
                var emterpretURLBytes = tryParseAsDataURI(emterpretURL);
                if (emterpretURLBytes) {
                  Module.emterpreterFile = emterpretURLBytes.buffer;
                }
              }
  %s
            };
            emterpretXHR.send(null);
  ''' % (shared.JS.get_subresource_location(shared.Settings.EMTERPRETIFY_FILE), script.inline)
  
      if options.memory_init_file and not shared.Settings.MEM_INIT_IN_WASM:
        # start to load the memory init file in the HTML, in parallel with the JS
        script.un_src()
        script.inline = ('''
            var memoryInitializer = '%s';
            memoryInitializer = Module['locateFile'] ? Module['locateFile'](memoryInitializer, '') : memoryInitializer;
            Module['memoryInitializerRequestURL'] = memoryInitializer;
            var meminitXHR = Module['memoryInitializerRequest'] = new XMLHttpRequest();
            meminitXHR.open('GET', memoryInitializer, true);
            meminitXHR.responseType = 'arraybuffer';
            meminitXHR.send(null);
  ''' % shared.JS.get_subresource_location(memfile)) + script.inline
  
      # Download .asm.js if --separate-asm was passed in an asm.js build, or if 'asmjs' is one
      # of the wasm run methods.
      if not options.separate_asm or shared.Settings.WASM:
        if len(asm_mods):
           exit_with_error('no --separate-asm means no client code mods are possible')
      else:
        script.un_src()
        if len(asm_mods) == 0:
          # just load the asm, then load the rest
          script.inline = '''
      var filename = '%s';
      var fileBytes = tryParseAsDataURI(filename);
      var script = document.createElement('script');
      if (fileBytes) {
        script.innerHTML = intArrayToString(fileBytes);
      } else {
        script.src = filename;
      }
      script.onload = function() {
        setTimeout(function() {
          %s
        }, 1); // delaying even 1ms is enough to allow compilation memory to be reclaimed
      };
      document.body.appendChild(script);
  ''' % (shared.JS.get_subresource_location(asm_target), script.inline)
        else:
          # may need to modify the asm code, load it as text, modify, and load asynchronously
          script.inline = '''
      var codeURL = '%s';
      var codeXHR = new XMLHttpRequest();
      codeXHR.open('GET', codeURL, true);
      codeXHR.onload = function() {
        var code;
        if (codeXHR.status === 200 || codeXHR.status === 0) {
          code = codeXHR.responseText;
        } else {
          var codeURLBytes = tryParseAsDataURI(codeURL);
          if (codeURLBytes) {
            code = intArrayToString(codeURLBytes);
          }
        }
        %s
        var blob = new Blob([code], { type: 'text/javascript' });
        codeXHR = null;
        var src = URL.createObjectURL(blob);
        var script = document.createElement('script');
        script.src = src;
        script.onload = function() {
          setTimeout(function() {
            %s
          }, 1); // delaying even 1ms is enough to allow compilation memory to be reclaimed
          URL.revokeObjectURL(script.src);
        };
        document.body.appendChild(script);
      };
      codeXHR.send(null);
  ''' % (shared.JS.get_subresource_location(asm_target), '\n'.join(asm_mods), script.inline)
  
      if shared.Settings.WASM and not shared.Settings.WASM_ASYNC_COMPILATION:
        # We need to load the wasm file before anything else, it has to be synchronously ready TODO: optimize
        script.un_src()
        script.inline = '''
            var wasmURL = '%s';
            var wasmXHR = new XMLHttpRequest();
            wasmXHR.open('GET', wasmURL, true);
            wasmXHR.responseType = 'arraybuffer';
            wasmXHR.onload = function() {
              if (wasmXHR.status === 200 || wasmXHR.status === 0) {
                Module.wasmBinary = wasmXHR.response;
              } else {
                var wasmURLBytes = tryParseAsDataURI(wasmURL);
                if (wasmURLBytes) {
                  Module.wasmBinary = wasmURLBytes.buffer;
                }
              }
  %s
            };
            wasmXHR.send(null);
  ''' % (shared.JS.get_subresource_location(wasm_binary_target), script.inline)
  
    # when script.inline isn't empty, add required helper functions such as tryParseAsDataURI
    if script.inline:
      for filename in ('arrayUtils.js', 'base64Utils.js', 'URIUtils.js'):
        content = read_and_preprocess(shared.path_from_root('src', filename))
        script.inline = content + script.inline
  
      script.inline = 'var ASSERTIONS = %s;\n%s' % (shared.Settings.ASSERTIONS, script.inline)
  
    # inline script for SINGLE_FILE output
    if shared.Settings.SINGLE_FILE:
      js_contents = script.inline or ''
      if script.src:
        js_contents += open(js_target).read()
      shared.try_delete(js_target)
      script.src = None
      script.inline = js_contents
  
    html_contents = shell.replace('{{{ SCRIPT }}}', script.replacement())
    html_contents = tools.line_endings.convert_line_endings(html_contents, '\n', options.output_eol)
    with open(target, 'wb') as f:
      f.write(asbytes(html_contents))
  
  
  def minify_html(filename, options):
    opts = []
    # -g1 and greater retain whitespace and comments in source
    if options.debug_level == 0:
      opts += ['--collapse-whitespace',
               '--collapse-inline-tag-whitespace',
               '--remove-comments',
               '--remove-tag-whitespace',
               '--sort-attributes',
               '--sort-class-name']
    # -g2 and greater do not minify HTML at all
    if options.debug_level <= 1:
      opts += ['--decode-entities',
               '--collapse-boolean-attributes',
               '--remove-attribute-quotes',
               '--remove-redundant-attributes',
               '--remove-script-type-attributes',
               '--remove-style-link-type-attributes',
               '--use-short-doctype',
               '--minify-css', 'true',
               '--minify-js', 'true']
  
    # html-minifier also has the following options, but they look unsafe for use:
    # '--remove-optional-tags': removes e.g. <head></head> and <body></body> tags from the page.
    #                           (Breaks at least browser.test_sdl2glshader)
    # '--remove-empty-attributes': removes all attributes with whitespace-only values.
    #                              (Breaks at least browser.test_asmfs_hello_file)
    # '--remove-empty-elements': removes all elements with empty contents.
    #                            (Breaks at least browser.test_asm_swapping)
  
    if options.debug_level >= 2:
      return
  
    logger.debug('minifying HTML file ' + filename)
    size_before = os.path.getsize(filename)
    start_time = time.time()
    run_process(shared.NODE_JS + [shared.path_from_root('third_party', 'html-minifier', 'cli.js'), filename, '-o', filename] + opts)
    elapsed_time = time.time() - start_time
    size_after = os.path.getsize(filename)
    delta = size_after - size_before
    logger.debug('HTML minification took {:.2f}'.format(elapsed_time) + ' seconds, and shrunk size of ' + filename + ' from ' + str(size_before) + ' to ' + str(size_after) + ' bytes, delta=' + str(delta) + ' ({:+.2f}%)'.format(delta * 100.0 / size_before))
  
  
  def generate_html(target, options, js_target, target_basename,
                    asm_target, wasm_binary_target,
                    memfile, optimizer):
    logger.debug('generating HTML')
  
    if shared.Settings.MINIMAL_RUNTIME:
      generate_minimal_runtime_html(target, options, js_target, target_basename, asm_target,
                                    wasm_binary_target, memfile, optimizer)
    else:
      generate_traditional_runtime_html(target, options, js_target, target_basename, asm_target,
                                        wasm_binary_target, memfile, optimizer)
  
    if shared.Settings.MINIFY_HTML and (options.opt_level >= 1 or options.shrink_level >= 1):
      minify_html(target, options)
  
  
  def generate_worker_js(target, js_target, target_basename):
    # compiler output is embedded as base64
    if shared.Settings.SINGLE_FILE:
      proxy_worker_filename = shared.JS.get_subresource_location(js_target)
  
    # compiler output goes in .worker.js file
    else:
      shutil.move(js_target, unsuffixed(js_target) + '.worker.js')
      worker_target_basename = target_basename + '.worker'
      proxy_worker_filename = (shared.Settings.PROXY_TO_WORKER_FILENAME or worker_target_basename) + '.js'
  
    target_contents = worker_js_script(proxy_worker_filename)
    open(target, 'w').write(target_contents)
  
  
  def worker_js_script(proxy_worker_filename):
    web_gl_client_src = open(shared.path_from_root('src', 'webGLClient.js')).read()
    idb_store_src = open(shared.path_from_root('src', 'IDBStore.js')).read()
    proxy_client_src = (
      open(shared.path_from_root('src', 'proxyClient.js')).read()
      .replace('{{{ filename }}}', proxy_worker_filename)
      .replace('{{{ IDBStore.js }}}', idb_store_src)
    )
  
    return web_gl_client_src + '\n' + proxy_client_src
  
  
  def process_libraries(libs, lib_dirs, temp_files):
    libraries = []
    consumed = []
  
    # Find library files
    for i, lib in libs:
      logger.debug('looking for library "%s"', lib)
      suffixes = STATICLIB_ENDINGS + DYNAMICLIB_ENDINGS
  
      if shared.Settings.WASM_BACKEND:
        # under the wasm .a files are found using the normal -l/-L flags to
        # the linker.
        suffixes = DYNAMICLIB_ENDINGS
  
      found = False
      for prefix in LIB_PREFIXES:
        for suff in suffixes:
          name = prefix + lib + suff
          for lib_dir in lib_dirs:
            path = os.path.join(lib_dir, name)
            if os.path.exists(path):
              logger.debug('found library "%s" at %s', lib, path)
              temp_files.append((i, path))
              consumed.append(i)
              found = True
              break
          if found:
            break
        if found:
          break
      if not found:
        jslibs = shared.Building.path_to_system_js_libraries(lib)
        if jslibs:
          libraries += jslibs
          consumed.append(i)
  
    shared.Settings.SYSTEM_JS_LIBRARIES = libraries
    return consumed
  
  
  class ScriptSource(object):
    def __init__(self):
      self.src = None # if set, we have a script to load with a src attribute
      self.inline = None # if set, we have the contents of a script to write inline in a script
  
    def un_src(self):
      """Use this if you want to modify the script and need it to be inline."""
      if self.src is None:
        return
      self.inline = '''
            var script = document.createElement('script');
            script.src = "%s";
            document.body.appendChild(script);
  ''' % self.src
      self.src = None
  
    def replacement(self):
      """Returns the script tag to replace the {{{ SCRIPT }}} tag in the target"""
      assert (self.src or self.inline) and not (self.src and self.inline)
      if self.src:
        return '<script async type="text/javascript" src="%s"></script>' % quote(self.src)
      else:
        return '<script>\n%s\n</script>' % self.inline
  
  
  def is_valid_abspath(options, path_name):
    # Any path that is underneath the emscripten repository root must be ok.
    if shared.path_from_root().replace('\\', '/') in path_name.replace('\\', '/'):
      return True
  
    def in_directory(root, child):
      # make both path absolute
      root = os.path.realpath(root)
      child = os.path.realpath(child)
  
      # return true, if the common prefix of both is equal to directory
      # e.g. /a/b/c/d.rst and directory is /a/b, the common prefix is /a/b
      return os.path.commonprefix([root, child]) == root
  
    for valid_abspath in options.valid_abspaths:
      if in_directory(valid_abspath, path_name):
        return True
    return False
  
  
  def parse_value(text):
    # Note that using response files can introduce whitespace, if the file
    # has a newline at the end. For that reason, we rstrip() in relevant
    # places here.
    def parse_string_value(text):
      first = text[0]
      if first == "'" or first == '"':
        text = text.rstrip()
        assert text[-1] == text[0] and len(text) > 1, 'unclosed opened quoted string. expected final character to be "%s" and length to be greater than 1 in "%s"' % (text[0], text)
        return text[1:-1]
      return text
  
    def parse_string_list_members(text):
      sep = ','
      values = text.split(sep)
      result = []
      index = 0
      while True:
        current = values[index].lstrip() # Cannot safely rstrip for cases like: "HERE-> ,"
        if not len(current):
          exit_with_error('string array should not contain an empty value')
        first = current[0]
        if not(first == "'" or first == '"'):
          result.append(current.rstrip())
        else:
          start = index
          while True: # Continue until closing quote found
            if index >= len(values):
              exit_with_error("unclosed quoted string. expected final character to be '%s' in '%s'" % (first, values[start]))
            new = values[index].rstrip()
            if new and new[-1] == first:
              if start == index:
                result.append(current.rstrip()[1:-1])
              else:
                result.append((current + sep + new)[1:-1])
              break
            else:
              current += sep + values[index]
              index += 1
  
        index += 1
        if index >= len(values):
          break
      return result
  
    def parse_string_list(text):
      text = text.rstrip()
      if text[-1] != ']':
        exit_with_error('unclosed opened string list. expected final character to be "]" in "%s"' % (text))
      inner = text[1:-1]
      if inner.strip() == "":
        return []
      return parse_string_list_members(inner)
  
    if text[0] == '[':
      # if json parsing fails, we fall back to our own parser, which can handle a few
      # simpler syntaxes
      try:
        return json.loads(text)
      except ValueError:
        return parse_string_list(text)
  
    try:
      return int(text)
    except ValueError:
      return parse_string_value(text)
  
  
  def validate_arg_level(level_string, max_level, err_msg, clamp=False):
    try:
      level = int(level_string)
    except ValueError:
      raise Exception(err_msg)
    if clamp:
      if level > max_level:
        logger.warning("optimization level '-O" + level_string + "' is not supported; using '-O" + str(max_level) + "' instead")
        level = max_level
    if not 0 <= level <= max_level:
      raise Exception(err_msg)
    return level
  
  
  if __name__ == '__main__':
    try:
      sys.exit(run(sys.argv))
    except KeyboardInterrupt:
      logger.warning("KeyboardInterrupt")
      sys.exit(1)
  