emcc.py

#!/usr/bin/env python2
# -*- Mode: python -*-

'''
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.
'''

import os, sys, shutil, tempfile, subprocess, shlex, time, re, logging
from subprocess import PIPE
from tools import shared, jsrun, system_libs
from tools.shared import execute, suffix, unsuffixed, unsuffixed_basename, WINDOWS, safe_move
from tools.response_file import read_response_file

# 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

BITCODE_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')
SUPPORTED_LINKER_FLAGS = ('--start-group', '-(', '--end-group', '-)')

LIB_PREFIXES = ('', 'lib')

JS_CONTAINING_SUFFIXES = ('js', 'html')

DEFERRED_REPONSE_FILES = ('EMTERPRETIFY_BLACKLIST', 'EMTERPRETIFY_WHITELIST')

# 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: 0,
  1: 1,
  2: 3,
  3: 3,
}

DEBUG = os.environ.get('EMCC_DEBUG')
if DEBUG == "0":
  DEBUG = None

TEMP_DIR = os.environ.get('EMCC_TEMP_DIR')
LEAVE_INPUTS_RAW = os.environ.get('EMCC_LEAVE_INPUTS_RAW') # 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
# 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']
AUTODEBUG = os.environ.get('EMCC_AUTODEBUG') # 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
EMCC_CFLAGS = os.environ.get('EMCC_CFLAGS') # Additional compiler flags that we treat as if they were passed to us on the commandline

# Target options
final = None
target = None
script_src = None # if set, we have a script to load with a src attribute
script_inline = None # if set, we have the contents of a script to write inline in a script

#
# Main run() function
#
def run():
  global final, target, script_src, script_inline

  if DEBUG: logging.warning('invocation: ' + ' '.join(sys.argv) + (' + ' + EMCC_CFLAGS if EMCC_CFLAGS else '') + '  (in ' + os.getcwd() + ')')
  if EMCC_CFLAGS: sys.argv.append(EMCC_CFLAGS)

  if DEBUG and LEAVE_INPUTS_RAW: logging.warning('leaving inputs raw')

  stdout = PIPE if not DEBUG else None # suppress output of child processes
  stderr = PIPE if not DEBUG else None # unless we are in DEBUG mode

  EMCC_CXX = '--emscripten-cxx' in sys.argv
  sys.argv = filter(lambda x: x != '--emscripten-cxx', sys.argv)

  if len(sys.argv) <= 1 or ('--help' not in sys.argv and len(sys.argv) >= 2 and sys.argv[1] != '--version'):
    shared.check_sanity(force=DEBUG)

  # Handle some global flags

  if len(sys.argv) == 1:
    logging.warning('no input files')
    exit(1)

  # read response files very early on
  response_file = True
  while response_file:
    response_file = None
    for index in range(1, len(sys.argv)):
      if sys.argv[index][0] == '@':
        # found one, loop again next time
        response_file = True
        extra_args = read_response_file(sys.argv[index])
        # slice in extra_args in place of the response file arg
        sys.argv[index:index+1] = extra_args
        break

  if len(sys.argv) == 1 or '--help' in sys.argv:
    # 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())
    exit(0)

  elif sys.argv[1] == '--version':
    revision = '(unknown revision)'
    here = os.getcwd()
    os.chdir(shared.path_from_root())
    try:
      revision = execute(['git', 'show'], stdout=PIPE, stderr=PIPE)[0].split('\n')[0]
    except:
      pass
    finally:
      os.chdir(here)
    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)
    exit(0)

  elif len(sys.argv) == 2 and sys.argv[1] == '-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
    code = subprocess.call([shared.CLANG, '-v'])
    shared.check_sanity(force=True)
    exit(code)

  elif '-dumpmachine' in sys.argv:
    print shared.get_llvm_target()
    exit(0)

  def is_minus_s_for_emcc(newargs, i):
    assert newargs[i] == '-s'
    if i+1 < len(newargs) and '=' in newargs[i+1] and not newargs[i+1].startswith('-'): # -s OPT=VALUE is for us, -s by itself is a linker option
      return True
    else:
      logging.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 sys.argv) and not os.environ.get('EMMAKEN_JUST_CONFIGURE_RECURSE')
  CMAKE_CONFIG = 'CMakeFiles/cmTryCompileExec.dir' in ' '.join(sys.argv)# or 'CMakeCCompilerId' in ' '.join(sys.argv)
  if CONFIGURE_CONFIG or CMAKE_CONFIG:
    debug_configure = 0 # XXX use this to debug configure stuff. ./configure's generally hide our normal output including stderr so we write to a file

    # Whether we fake configure tests using clang - the local, native compiler - or not. if not we generate JS and use node with a shebang
    # Beither 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') or 1)

    if debug_configure:
      tempout = '/tmp/emscripten_temp/out'
      if not os.path.exists(tempout):
        open(tempout, 'w').write('//\n')

    src = None
    for arg in sys.argv:
      if arg.endswith(SOURCE_ENDINGS):
        try:
          src = open(arg).read()
          if debug_configure: open(tempout, 'a').write('============= ' + arg + '\n' + src + '\n=============\n\n')
        except:
          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')

    compiler = os.environ.get('CONFIGURE_CC') or (shared.CLANG if not use_js else shared.EMCC) # if CONFIGURE_CC is defined, use that. let's you use local gcc etc. if you need that
    if not ('CXXCompiler' in ' '.join(sys.argv) or EMCC_CXX):
      compiler = shared.to_cc(compiler)

    def filter_emscripten_options(argv):
      idx = 0
      skip_next = False
      for el in argv:
        if skip_next:
          skip_next = False
          idx += 1
          continue
        if not use_js and el == '-s' and is_minus_s_for_emcc(argv, idx): # skip -s X=Y if not using js for configure
          skip_next = True
        else:
          yield el
        idx += 1

    if compiler == shared.EMCC: compiler = [shared.PYTHON, shared.EMCC]
    else: compiler = [compiler] 
    cmd = compiler + list(filter_emscripten_options(sys.argv[1:]))
    if not use_js: cmd += shared.EMSDK_OPTS + ['-D__EMSCRIPTEN__', '-DEMSCRIPTEN']
    if use_js: cmd += ['-s', 'ERROR_ON_UNDEFINED_SYMBOLS=1'] # configure tests should fail when an undefined symbol exists

    logging.debug('just configuring: ' + ' '.join(cmd))
    if debug_configure: open(tempout, 'a').write('emcc, just configuring: ' + ' '.join(cmd) + '\n\n')

    if not use_js:
      exit(subprocess.call(cmd))
    else:
      only_object = '-c' in cmd
      for i in range(len(cmd)-1):
        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 = subprocess.call(cmd)
      os.environ['EMMAKEN_JUST_CONFIGURE_RECURSE'] = ''
      if not os.path.exists(target): exit(ret) # 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 to exit(ret) is fine
      if target.endswith('.js'):
        shutil.copyfile(target, target[:-3])
        target = target[:-3]
      if not target.endswith(BITCODE_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
        import stat
        try:
          os.chmod(target, stat.S_IMODE(os.stat(target).st_mode) | stat.S_IXUSR) # make executable
        except:
          pass # can fail if e.g. writing the executable to /dev/null
      exit(ret)

  if os.environ.get('EMMAKEN_COMPILER'):
    CXX = os.environ['EMMAKEN_COMPILER']
  else:
    CXX = shared.CLANG

  CC = shared.to_cc(CXX)

  # If we got here from a redirection through emmakenxx.py, then force a C++ compiler here
  if EMCC_CXX:
    CC = CXX

  CC_ADDITIONAL_ARGS = shared.COMPILER_OPTS

  EMMAKEN_CFLAGS = os.environ.get('EMMAKEN_CFLAGS')
  if EMMAKEN_CFLAGS: sys.argv += shlex.split(EMMAKEN_CFLAGS)

  # ---------------- Utilities ---------------

  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)) if suffix(name) else '')

  # ---------------- End configs -------------

  if len(sys.argv) == 1 or sys.argv[1] in ['x', 't']:
    # noop ar
    logging.debug('just ar')
    sys.exit(0)

  use_cxx = True

  for i in range(1, len(sys.argv)):
    arg = sys.argv[i]
    if not arg.startswith('-'):
      if arg.endswith(C_ENDINGS + OBJC_ENDINGS):
        use_cxx = False

  # Check if a target is specified
  target = None
  for i in range(len(sys.argv)-1):
    if sys.argv[i].startswith('-o='):
      raise Exception('Invalid syntax: do not use -o=X, use -o X')

    if sys.argv[i] == '-o':
      target = sys.argv[i+1]
      sys.argv = sys.argv[:i] + sys.argv[i+2:]
      break

  specified_target = target
  target = specified_target if specified_target is not None else 'a.out.js' # specified_target is the user-specified one, target is what we will generate
  target_basename = unsuffixed_basename(target)

  if '.' in target:
    final_suffix = target.split('.')[-1]
  else:
    final_suffix = ''

  if TEMP_DIR:
    temp_dir = TEMP_DIR
    if os.path.exists(temp_dir):
      shutil.rmtree(temp_dir) # clear it
    os.makedirs(temp_dir)
  else:
    temp_root = shared.TEMP_DIR
    if not os.path.exists(temp_root):
      os.makedirs(temp_root)
    temp_dir = tempfile.mkdtemp(dir=temp_root)

  def in_temp(name):
    return os.path.join(temp_dir, os.path.basename(name))

  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

  # 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'
  def filename_type_suffix(filename):
    for i in reversed(filename.split('.')[1:]):
      if not i.isdigit():
        return i
    return ''

  def filename_type_ending(filename):
    if filename in SPECIAL_ENDINGLESS_FILENAMES:
      return filename
    suffix = filename_type_suffix(filename)
    return '' if not suffix else ('.' + suffix)

  # Log out times for emcc stages
  class TimeLogger:
    last = time.time()
  def log_time(name):
    now = time.time()
    logging.debug('emcc step "%s" took %.2f seconds', name, now - TimeLogger.last)
    TimeLogger.last = now

  misc_temp_files = shared.configuration.get_temp_files()

  try:
    call = CXX if use_cxx else CC

    ## Parse args

    newargs = sys.argv[1:]

    opt_level = 0
    debug_level = 0
    shrink_level = 0
    requested_debug = ''
    profiling = False
    profiling_funcs = False
    tracing = False
    emit_symbol_map = False
    js_opts = None
    llvm_opts = None
    llvm_lto = None
    use_closure_compiler = None
    js_transform = None
    pre_js = ''
    post_js = ''
    preload_files = []
    embed_files = []
    exclude_files = []
    ignore_dynamic_linking = False
    shell_path = shared.path_from_root('src', 'shell.html')
    js_libraries = []
    bind = False
    emrun = False
    cpu_profiler = False
    thread_profiler = False
    memory_profiler = False
    save_bc = False
    memory_init_file = None
    use_preload_cache = False
    no_heap_copy = False
    use_preload_plugins = False
    proxy_to_worker = False
    default_object_extension = '.o'
    valid_abspaths = []
    separate_asm = False

    def is_valid_abspath(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

      for valid_abspath in valid_abspaths:
        if in_directory(valid_abspath, path_name):
          return True
      return False


    if use_cxx:
      default_cxx_std = '-std=c++03' # Enforce a consistent C++ standard when compiling .cpp files, if user does not specify one on the cmdline.
    else:
      default_cxx_std = '' # Compiling C code with .c files, don't enforce a default C++ std.

    def check_bad_eq(arg):
      assert '=' not in arg, 'Invalid parameter (do not use "=" with "--" options)'

    # Defaults to not showing absolute path warnings
    absolute_warning_shown = True

    for i in range(len(newargs)):
      # Scan for path warning flag in advance from other cmdline flags, so that it works even if -I or -L directives are present before this.
      if newargs[i] == '-Wwarn-absolute-paths':
        newargs[i] = ''
        absolute_warning_shown = False
      elif newargs[i] == '-Wno-warn-absolute-paths':
        newargs[i] = ''
        absolute_warning_shown = True
      elif 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] = ''

    settings_changes = []

    def validate_arg_level(level_string, max_level, err_msg):
      try:
        level = int(level_string)
        assert 0 <= level <= max_level
      except:
        raise Exception(err_msg)
      return level

    should_exit = False

    for i in range(len(newargs)):
      newargs[i] = newargs[i].strip() # 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'
      if newargs[i].startswith('-O'):
        # Let -O default to -O2, which is what gcc does.
        requested_level = newargs[i][2:] or '2'
        if requested_level == 's':
          llvm_opts = ['-Os']
          requested_level = 2
          shrink_level = 1
          settings_changes.append('INLINING_LIMIT=50')
        elif requested_level == 'z':
          llvm_opts = ['-Oz']
          requested_level = 2
          shrink_level = 2
          settings_changes.append('INLINING_LIMIT=25')
        opt_level = validate_arg_level(requested_level, 3, 'Invalid optimization level: ' + newargs[i])
        # 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.
        newargs.append('-mllvm')
        newargs.append('-disable-llvm-optzns')
      elif newargs[i].startswith('--js-opts'):
        check_bad_eq(newargs[i])
        js_opts = eval(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--llvm-opts'):
        check_bad_eq(newargs[i])
        llvm_opts = eval(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--llvm-lto'):
        check_bad_eq(newargs[i])
        llvm_lto = eval(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--closure'):
        check_bad_eq(newargs[i])
        use_closure_compiler = int(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--js-transform'):
        check_bad_eq(newargs[i])
        js_transform = newargs[i+1]
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--pre-js'):
        check_bad_eq(newargs[i])
        pre_js += open(newargs[i+1]).read() + '\n'
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--post-js'):
        check_bad_eq(newargs[i])
        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'
        debug_level = max(1, debug_level)
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('-g'):
        requested_level = newargs[i][2:] or '3'
        debug_level = validate_arg_level(requested_level, 4, 'Invalid debug level: ' + newargs[i])
        requested_debug = newargs[i]
        newargs[i] = ''
      elif newargs[i] == '-profiling' or newargs[i] == '--profiling':
        debug_level = 2
        profiling = True
        newargs[i] = ''
      elif newargs[i] == '-profiling-funcs' or newargs[i] == '--profiling-funcs':
        profiling_funcs = True
        newargs[i] = ''
      elif newargs[i] == '--tracing' or newargs[i] == '--memoryprofiler':
        if newargs[i] == '--memoryprofiler':
          memory_profiler = True
        tracing = True
        newargs[i] = ''
        newargs.append('-D__EMSCRIPTEN_TRACING__=1')
        settings_changes.append("EMSCRIPTEN_TRACING=1")
        js_libraries.append(shared.path_from_root('src', 'library_trace.js'))
      elif newargs[i] == '--emit-symbol-map':
        emit_symbol_map = True
        newargs[i] = ''
      elif newargs[i] == '--bind':
        bind = True
        newargs[i] = ''
        js_libraries.append(shared.path_from_root('src', 'embind', 'emval.js'))
        js_libraries.append(shared.path_from_root('src', 'embind', 'embind.js'))
        if default_cxx_std:
          default_cxx_std = '-std=c++11' # Force C++11 for embind code, but only if user has not explicitly overridden a standard.
      elif newargs[i].startswith('-std=') or newargs[i].startswith('--std='):
        default_cxx_std = '' # User specified a standard to use, clear Emscripten from specifying it.
      elif newargs[i].startswith('--embed-file'):
        check_bad_eq(newargs[i])
        embed_files.append(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--preload-file'):
        check_bad_eq(newargs[i])
        preload_files.append(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--exclude-file'):
        check_bad_eq(newargs[i])
        exclude_files.append(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--use-preload-cache'):
        use_preload_cache = True
        newargs[i] = ''
      elif newargs[i].startswith('--no-heap-copy'):
        no_heap_copy = True
        newargs[i] = ''
      elif newargs[i].startswith('--use-preload-plugins'):
        use_preload_plugins = True
        newargs[i] = ''
      elif newargs[i] == '--ignore-dynamic-linking':
        ignore_dynamic_linking = True
        newargs[i] = ''
      elif newargs[i] == '-v':
        shared.COMPILER_OPTS += ['-v']
        shared.check_sanity(force=True)
        newargs[i] = ''
      elif newargs[i].startswith('--shell-file'):
        check_bad_eq(newargs[i])
        shell_path = newargs[i+1]
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i].startswith('--js-library'):
        check_bad_eq(newargs[i])
        js_libraries.append(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i] == '--remove-duplicates':
        logging.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':
        logging.error('jcache is no longer supported')
        newargs[i] = ''
      elif newargs[i] == '--cache':
        check_bad_eq(newargs[i])
        os.environ['EM_CACHE'] = newargs[i+1]
        shared.reconfigure_cache()
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i] == '--clear-cache':
        logging.warning('clearing 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':
        logging.warning('clearing ports')
        system_libs.Ports.erase()
        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])
        save_bc = newargs[i+1]
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i] == '--memory-init-file':
        check_bad_eq(newargs[i])
        memory_init_file = int(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i] == '--proxy-to-worker':
        proxy_to_worker = True
        newargs[i] = ''
      elif newargs[i] == '--valid-abspath':
        valid_abspaths.append(newargs[i+1])
        newargs[i] = ''
        newargs[i+1] = ''
      elif newargs[i] == '--separate-asm':
        separate_asm = True
        newargs[i] = ''
      elif newargs[i].startswith(('-I', '-L')):
        path_name = newargs[i][2:]
        if not absolute_warning_shown and os.path.isabs(path_name) and not is_valid_abspath(path_name):
          logging.warning('-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).') # 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
          absolute_warning_shown = True
      elif newargs[i] == '--emrun':
        emrun = True
        newargs[i] = ''
      elif newargs[i] == '--cpuprofiler':
        cpu_profiler = True
        newargs[i] = ''
      elif newargs[i] == '--threadprofiler':
        thread_profiler = True
        settings_changes.append('PTHREADS_PROFILING=1')
        newargs[i] = ''
      elif newargs[i] == '--default-obj-ext':
        newargs[i] = ''
        default_object_extension = newargs[i+1]
        if not default_object_extension.startswith('.'):
          default_object_extension = '.' + default_object_extension
        newargs[i+1] = ''
      elif newargs[i] == '-msse':
        newargs.append('-D__SSE__=1')
        newargs[i] = ''
      elif newargs[i] == '-msse2':
        newargs.append('-D__SSE__=1')
        newargs.append('-D__SSE2__=1')
        newargs[i] = ''
      elif newargs[i] == '-msse3':
        newargs.append('-D__SSE__=1')
        newargs.append('-D__SSE2__=1')
        newargs.append('-D__SSE3__=1')
        newargs[i] = ''
      elif newargs[i] == '-mssse3':
        newargs.append('-D__SSE__=1')
        newargs.append('-D__SSE2__=1')
        newargs.append('-D__SSE3__=1')
        newargs.append('-D__SSSE3__=1')
        newargs[i] = ''
      elif newargs[i] == '-msse4.1':
        newargs.append('-D__SSE__=1')
        newargs.append('-D__SSE2__=1')
        newargs.append('-D__SSE3__=1')
        newargs.append('-D__SSSE3__=1')
        newargs.append('-D__SSE4_1__=1')
        newargs[i] = ''

    if should_exit:
      sys.exit(0)

    newargs = [arg for arg in newargs if arg is not '']

    # If user did not specify a default -std for C++ code, specify the emscripten default.
    if default_cxx_std:
      newargs = newargs + [default_cxx_std]

    if emrun:
      pre_js += open(shared.path_from_root('src', 'emrun_prejs.js')).read() + '\n'
      post_js += open(shared.path_from_root('src', 'emrun_postjs.js')).read() + '\n'

    if cpu_profiler:
      post_js += open(shared.path_from_root('src', 'cpuprofiler.js')).read() + '\n'

    if memory_profiler:
      post_js += open(shared.path_from_root('src', 'memoryprofiler.js')).read() + '\n'

    if thread_profiler:
      post_js += open(shared.path_from_root('src', 'threadprofiler.js')).read() + '\n'

    if js_opts is None: js_opts = opt_level >= 2
    if llvm_opts is None: llvm_opts = LLVM_OPT_LEVEL[opt_level]
    if opt_level == 0: debug_level = max(3, debug_level)
    if memory_init_file is None: memory_init_file = opt_level >= 2

    # TODO: support source maps with js_transform
    if js_transform and debug_level >= 4:
      logging.warning('disabling source maps because a js transform is being done')
      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):
          settings_changes.append(newargs[i+1])
          newargs[i] = newargs[i+1] = ''
    newargs = [arg for arg in newargs if arg is not '']

    # 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 = [shared.path_from_root('system', 'local', 'lib'),
                shared.path_from_root('system', 'lib')]
    for i in range(len(newargs)): # find input files XXX 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
      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 os.path.islink(arg) and os.path.realpath(arg).endswith(SOURCE_ENDINGS + BITCODE_ENDINGS + DYNAMICLIB_ENDINGS + ASSEMBLY_ENDINGS + HEADER_ENDINGS):
        arg = os.path.realpath(arg)

      if not arg.startswith('-'):
        if not os.path.exists(arg):
          logging.error('%s: No such file or directory ("%s" was expected to be an input file, based on the commandline arguments provided)', arg, arg)
          exit(1)

        arg_ending = filename_type_ending(arg)
        if arg_ending.endswith(SOURCE_ENDINGS + BITCODE_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 arg_ending.endswith(SOURCE_ENDINGS):
            input_files.append((i, arg))
            has_source_inputs = True
          elif arg_ending.endswith(HEADER_ENDINGS):
            input_files.append((i, arg))
            has_header_inputs = True
          elif arg_ending.endswith(ASSEMBLY_ENDINGS) or shared.Building.is_bitcode(arg): # this should be bitcode, make sure it is valid
            input_files.append((i, arg))
          elif arg_ending.endswith(STATICLIB_ENDINGS + DYNAMICLIB_ENDINGS):
            # if it's not, and it's a library, just add it to libs to find later
            l = unsuffixed_basename(arg)
            for prefix in LIB_PREFIXES:
              if not prefix: continue
              if l.startswith(prefix):
                l = l[len(prefix):]
                break
            libs.append((i, l))
            newargs[i] = ''
          else:
            logging.warning(arg + ' is not valid LLVM bitcode')
        elif arg_ending.endswith(STATICLIB_ENDINGS):
          if not shared.Building.is_ar(arg):
            if shared.Building.is_bitcode(arg):
              logging.error(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(BITCODE_ENDINGS))
            else:
              logging.error(arg + ': Unknown format, not a static library!')
            exit(1)
        else:
          logging.error(arg + ": Input file has an unknown suffix, don't know what to do with it!")
          exit(1)
      elif arg.startswith('-L'):
        lib_dirs.append(arg[2:])
        newargs[i] = ''
      elif arg.startswith('-l'):
        libs.append((i, arg[2:]))
        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):
          # Only keep flags that shared.Building.link knows how to deal with.
          # We currently can't handle flags with options (like
          # -Wl,-rpath,/bin:/lib, where /bin:/lib is an option for the -rpath
          # flag).
          if flag in SUPPORTED_LINKER_FLAGS:
            link_flags.append((i + float(flag_index) / len(link_flags_to_add), flag))
        newargs[i] = ''

    original_input_files = input_files[:]

    newargs = [arg for arg in newargs if arg is not '']

    # -c means do not link in gcc, and for us, the parallel is to not go all the way to JS, but stop at bitcode
    has_dash_c = '-c' in newargs
    if has_dash_c:
      assert has_source_inputs or has_header_inputs, 'Must have source code or header inputs to use -c'
      target = target_basename + '.o'
      final_suffix = 'o'
    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
    final_ending = ('.' + final_suffix) if len(final_suffix) > 0 else ''

    # target is now finalized, can finalize other _target s
    js_target = unsuffixed(target) + '.js'

    asm_target = js_target[:-3] + '.asm.js' # might not be used, but if it is, this is the name
    wasm_target = asm_target.replace('.asm.js', '.wast') # ditto, might not be used
    if final_suffix == 'html' and not separate_asm and 'PRECISE_F32=2' in settings_changes or 'USE_PTHREADS=2' in settings_changes:
      separate_asm = True
      logging.warning('forcing separate asm output (--separate-asm), because -s PRECISE_F32=2 or -s USE_PTHREADS=2 was passed.')
    if separate_asm:
      shared.Settings.SEPARATE_ASM = asm_target

    # Find library files
    for i, lib in libs:
      logging.debug('looking for library "%s"', lib)
      found = False
      for prefix in LIB_PREFIXES:
        for suff in STATICLIB_ENDINGS + DYNAMICLIB_ENDINGS:
          name = prefix + lib + suff
          for lib_dir in lib_dirs:
            path = os.path.join(lib_dir, name)
            if os.path.exists(path):
              logging.debug('found library "%s" at %s', lib, path)
              input_files.append((i, path))
              found = True
              break
          if found: break
        if found: break
      if not found and lib not in ['GL', 'GLU', 'glut', 'm', 'c', 'SDL', 'stdc++']: # whitelist our default libraries
        logging.warning('emcc: cannot find library "%s"', lib)

    # 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 not filename_type_suffix(target) in JS_CONTAINING_SUFFIXES or ignore_dynamic_linking:
      def check(input_file):
        if filename_type_ending(input_file) in DYNAMICLIB_ENDINGS:
          if not ignore_dynamic_linking: logging.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
      input_files = [(i, input_file) for (i, input_file) in input_files if check(input_file)]

    if len(input_files) == 0:
      logging.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 + BITCODE_ENDINGS + DYNAMICLIB_ENDINGS + STATICLIB_ENDINGS + ASSEMBLY_ENDINGS + HEADER_ENDINGS))
      exit(1)

    newargs = CC_ADDITIONAL_ARGS + newargs

    if separate_asm and final_suffix != 'html':
      logging.warning("--separate-asm works best when compiling to HTML. otherwise, you must yourself load the '.asm.js' file that is emitted separately, and must do so before loading the main '.js` file")

    # If we are using embind and generating JS, now is the time to link in bind.cpp
    if bind and final_suffix in JS_CONTAINING_SUFFIXES:
      input_files.append((next_arg_index, shared.path_from_root('system', 'lib', 'embind', 'bind.cpp')))
      next_arg_index += 1

    # Apply optimization level settings
    shared.Settings.apply_opt_level(opt_level, noisy=True)

    if os.environ.get('EMCC_FAST_COMPILER') == '0':
      logging.critical('Non-fastcomp compiler is no longer available, please use fastcomp or an older version of emscripten')
      sys.exit(1)

    # Set ASM_JS default here so that we can override it from the command line.
    shared.Settings.ASM_JS = 1 if opt_level > 0 else 2

    # Apply -s settings in newargs here (after optimization levels, so they can override them)
    for change in settings_changes:
      key, value = change.split('=')
      original_exported_response = False

      if value[0] == '@':
        if key not in DEFERRED_REPONSE_FILES:
          if key == 'EXPORTED_FUNCTIONS':
            original_exported_response = value
          value = open(value[1:]).read()
        else:
          value = '"' + value + '"'
      else:
        value = value.replace('\\', '\\\\')
      exec 'shared.Settings.' + key + ' = ' + value in globals(), locals()
      if key == 'EXPORTED_FUNCTIONS':
        # used for warnings in emscripten.py
        shared.Settings.ORIGINAL_EXPORTED_FUNCTIONS = original_exported_response or shared.Settings.EXPORTED_FUNCTIONS[:]

    try:
      assert shared.Settings.ASM_JS > 0, 'ASM_JS must be enabled in fastcomp'
      assert shared.Settings.SAFE_HEAP in [0, 1], 'safe heap must be 0 or 1 in fastcomp'
      assert shared.Settings.UNALIGNED_MEMORY == 0, 'forced unaligned memory not supported in fastcomp'
      assert shared.Settings.FORCE_ALIGNED_MEMORY == 0, 'forced aligned memory is not supported in fastcomp'
      assert shared.Settings.PGO == 0, 'pgo not supported in fastcomp'
      assert shared.Settings.QUANTUM_SIZE == 4, 'altering the QUANTUM_SIZE is not supported'
    except Exception, e:
      logging.error('Compiler settings are incompatible with fastcomp. You can fall back to the older compiler core, although that is not recommended, see http://kripken.github.io/emscripten-site/docs/building_from_source/LLVM-Backend.html')
      raise e

    assert not shared.Settings.PGO, 'cannot run PGO in ASM_JS mode'

    if shared.Settings.SAFE_HEAP and not js_opts:
      js_opts = True
      logging.debug('enabling js opts for SAFE_HEAP')

    if debug_level > 1 and use_closure_compiler:
      logging.warning('disabling closure because debug info was requested')
      use_closure_compiler = False

    assert not (shared.Settings.NO_DYNAMIC_EXECUTION and use_closure_compiler), 'cannot have both NO_DYNAMIC_EXECUTION and closure compiler enabled at the same time'

    if use_closure_compiler:
      shared.Settings.USE_CLOSURE_COMPILER = use_closure_compiler
      if not shared.check_closure_compiler():
        logging.error('fatal: closure compiler is not configured correctly')
        sys.exit(1)
      if use_closure_compiler == 2 and shared.Settings.ASM_JS == 1:
        logging.warning('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
      memory_init_file = False # memory init file is not supported with 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:
        shared.Settings.LINKABLE = 1
      shared.Settings.RELOCATABLE = 1
      shared.Settings.PRECISE_I64_MATH = 1 # other might use precise math, we need to be able to print it
      assert not use_closure_compiler, 'cannot use closure compiler on shared modules'
      assert not shared.Settings.ALLOW_MEMORY_GROWTH, 'memory growth is not supported with shared modules yet'

    if shared.Settings.ALLOW_MEMORY_GROWTH:
      logging.warning('not all asm.js optimizations are possible with ALLOW_MEMORY_GROWTH, disabling those')
      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

    if shared.Settings.EMULATE_FUNCTION_POINTER_CASTS:
      shared.Settings.ALIASING_FUNCTION_POINTERS = 0

    if shared.Settings.SPLIT_MEMORY:
      assert shared.Settings.SPLIT_MEMORY > shared.Settings.TOTAL_STACK, 'SPLIT_MEMORY must be at least TOTAL_STACK (stack must fit in first chunk)'
      assert shared.Settings.SPLIT_MEMORY & (shared.Settings.SPLIT_MEMORY-1) == 0, 'SPLIT_MEMORY must be a power of 2'
      if shared.Settings.ASM_JS == 1:
        logging.warning('not all asm.js optimizations are possible with SPLIT_MEMORY, disabling those')
        shared.Settings.ASM_JS = 2
      if shared.Settings.SAFE_HEAP:
        shared.Settings.SAFE_HEAP = 0
        shared.Settings.SAFE_SPLIT_MEMORY = 1 # we use our own infrastructure
      assert not shared.Settings.RELOCATABLE, 'no SPLIT_MEMORY with RELOCATABLE'
      assert not shared.Settings.USE_PTHREADS, 'no SPLIT_MEMORY with pthreads'
      if not js_opts:
        js_opts = True
        logging.debug('enabling js opts for SPLIT_MEMORY')
      if use_closure_compiler:
        use_closure_compiler = False
        logging.warning('cannot use closure compiler on split memory, for now, disabling')

    if shared.Settings.STB_IMAGE and final_suffix in JS_CONTAINING_SUFFIXES:
      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.DEMANGLE_SUPPORT:
      shared.Settings.EXPORTED_FUNCTIONS += ['___cxa_demangle']
      forced_stdlibs += ['libcxxabi']

    if not shared.Settings.ONLY_MY_CODE:
      if type(shared.Settings.EXPORTED_FUNCTIONS) in (list, tuple):
        # always need malloc and free to be kept alive and exported, for internal use and other modules
        for required_export in ['_malloc', '_free']:
          if required_export not in shared.Settings.EXPORTED_FUNCTIONS:
            shared.Settings.EXPORTED_FUNCTIONS.append(required_export)
      else:
        logging.debug('using response file for EXPORTED_FUNCTIONS, make sure it includes _malloc and _free')

    assert not (bind and shared.Settings.NO_DYNAMIC_EXECUTION), 'NO_DYNAMIC_EXECUTION disallows embind'

    assert not (shared.Settings.NO_DYNAMIC_EXECUTION and shared.Settings.RELOCATABLE), 'cannot have both NO_DYNAMIC_EXECUTION and RELOCATABLE enabled at the same time, since RELOCATABLE needs to eval()'

    if shared.Settings.RELOCATABLE:
      assert shared.Settings.GLOBAL_BASE < 1
      if shared.Settings.EMULATED_FUNCTION_POINTERS == 0:
        shared.Settings.EMULATED_FUNCTION_POINTERS = 2 # by default, use optimized function pointer emulation
      shared.Settings.ERROR_ON_UNDEFINED_SYMBOLS = shared.Settings.WARN_ON_UNDEFINED_SYMBOLS = 0
      if not shared.Settings.SIDE_MODULE:
        shared.Settings.EXPORT_ALL = 1

    if shared.Settings.EMTERPRETIFY:
      shared.Settings.FINALIZE_ASM_JS = 0
      #shared.Settings.GLOBAL_BASE = 8*256 # keep enough space at the bottom for a full stack frame, for z-interpreter
      shared.Settings.SIMPLIFY_IFS = 0 # this is just harmful for emterpreting
      shared.Settings.EXPORTED_FUNCTIONS += ['emterpret']
      if not js_opts:
        js_opts = True
        logging.debug('enabling js opts for EMTERPRETIFY')
      assert use_closure_compiler is not 2, 'EMTERPRETIFY requires valid asm.js, and is incompatible with closure 2 which disables that'

    if shared.Settings.DEAD_FUNCTIONS and not js_opts:
      js_opts = True
      logging.debug('enabling js opts for DEAD_FUNCTIONS')

    if proxy_to_worker:
      shared.Settings.PROXY_TO_WORKER = 1

    if use_preload_plugins or len(preload_files) > 0 or len(embed_files) > 0:
      # if we include any files, or intend to use preload plugins, then we definitely need filesystem support
      shared.Settings.FORCE_FILESYSTEM = 1

    if proxy_to_worker or use_preload_plugins:
      shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$Browser']

    if js_opts:
      shared.Settings.RUNNING_JS_OPTS = 1

    if not shared.Settings.NO_FILESYSTEM and not shared.Settings.ONLY_MY_CODE:
      shared.Settings.EXPORTED_FUNCTIONS += ['___errno_location'] # so FS can report errno back to C
      if not shared.Settings.NO_EXIT_RUNTIME:
        shared.Settings.EXPORTED_FUNCTIONS += ['_fflush'] # to flush the streams on FS quit
                                                          # TODO this forces 4 syscalls, maybe we should avoid it?

    if shared.Settings.USE_PTHREADS:
      if not any(s.startswith('PTHREAD_POOL_SIZE=') for s in settings_changes):
        settings_changes.append('PTHREAD_POOL_SIZE=0')
      js_libraries.append(shared.path_from_root('src', 'library_pthread.js'))
      newargs.append('-D__EMSCRIPTEN_PTHREADS__=1')
      shared.Settings.FORCE_FILESYSTEM = 1 # proxying of utime requires the filesystem
    else:
      js_libraries.append(shared.path_from_root('src', 'library_pthread_stub.js'))

    if shared.Settings.USE_PTHREADS:
      if shared.Settings.PROXY_TO_WORKER:
        logging.error('-s PROXY_TO_WORKER=1 is not yet supported with -s USE_PTHREADS=1!')
        exit(1)
      if shared.Settings.LINKABLE:
        logging.error('-s LINKABLE=1 is not supported with -s USE_PTHREADS=1!')
        exit(1)
      if shared.Settings.SIDE_MODULE:
        logging.error('-s SIDE_MODULE=1 is not supported with -s USE_PTHREADS=1!')
        exit(1)
      if shared.Settings.MAIN_MODULE:
        logging.error('-s MAIN_MODULE=1 is not supported with -s USE_PTHREADS=1!')
        exit(1)

    if shared.Settings.BINARYEN:
      debug_level = max(1, debug_level) # keep whitespace readable, for asm.js parser simplicity
      shared.Settings.GLOBAL_BASE = 1024 # leave some room for mapping global vars
      assert not shared.Settings.SPLIT_MEMORY, 'WebAssembly does not support split memory'

    if tracing:
      if shared.Settings.ALLOW_MEMORY_GROWTH:
        shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['emscripten_trace_report_memory_layout']

    if shared.Settings.ONLY_MY_CODE:
      shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE = []
      separate_asm = True
      shared.Settings.FINALIZE_ASM_JS = False

    shared.Settings.EMSCRIPTEN_VERSION = shared.EMSCRIPTEN_VERSION
    shared.Settings.OPT_LEVEL = opt_level
    shared.Settings.DEBUG_LEVEL = debug_level

    ## Compile source code to bitcode

    logging.debug('compiling to bitcode')

    temp_files = []

    log_time('parse arguments and setup')

    # 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 + shared.EMSDK_CXX_OPTS + headers
      if specified_target:
        args += ['-o', specified_target]
      args = system_libs.process_args(args, shared.Settings)
      logging.debug("running (for precompiled headers): " + call + ' ' + ' '.join(args))
      execute([call] + args) # let compiler frontend print directly, so colors are saved (PIPE kills that)
      sys.exit(0)

    def get_bitcode_file(input_file):
      if final_suffix not in JS_CONTAINING_SUFFIXES:
        # no need for a temp file, just emit to the right place
        if len(input_files) == 1:
          # can just emit directly to the target
          if specified_target:
            if specified_target.endswith('/') or specified_target.endswith('\\') or os.path.isdir(specified_target):
              return os.path.join(specified_target, os.path.basename(unsuffixed(input_file))) + default_object_extension
            return specified_target
          return unsuffixed(input_file) + final_ending
        else:
          if has_dash_c: return unsuffixed(input_file) + default_object_extension
      return in_temp(unsuffixed(uniquename(input_file)) + default_object_extension)

    # 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 debug_level >= 4 or ((final_suffix not in JS_CONTAINING_SUFFIXES or (has_source_inputs and final_suffix in JS_CONTAINING_SUFFIXES)) and requested_debug == '-g'):
      if debug_level == 4 or not (final_suffix in JS_CONTAINING_SUFFIXES and js_opts): # do not save llvm debug info if js optimizer will wipe it out anyhow (but if source maps are used, keep it)
        newargs.append('-g') # preserve LLVM debug info
        debug_level = 4

    # Bitcode args generation code
    def get_bitcode_args(input_files):
      file_ending = filename_type_ending(input_files[0])
      args = [call] + newargs + input_files
      if file_ending.endswith(CXX_ENDINGS):
        args += shared.EMSDK_CXX_OPTS
      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:
      input_files = map(lambda x: x[1], input_files)
      cmd = get_bitcode_args(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)
      logging.debug(('just preprocessor ' if '-E' in newargs else 'just dependencies: ') + ' '.join(cmd))
      exit(subprocess.call(cmd))

    # First, generate LLVM bitcode. For each input file, we get base.o with bitcode
    for i, input_file in input_files:
      file_ending = filename_type_ending(input_file)
      if file_ending.endswith(SOURCE_ENDINGS):
        logging.debug('compiling source file: ' + input_file)
        output_file = get_bitcode_file(input_file)
        temp_files.append((i, output_file))
        args = get_bitcode_args([input_file]) + ['-emit-llvm', '-c', '-o', output_file]
        logging.debug("running: " + ' '.join(args))
        execute(args) # let compiler frontend print directly, so colors are saved (PIPE kills that)
        if not os.path.exists(output_file):
          logging.error('compiler frontend failed to generate LLVM bitcode, halting')
          sys.exit(1)
      else: # bitcode
        if file_ending.endswith(BITCODE_ENDINGS):
          logging.debug('using bitcode file: ' + input_file)
          temp_files.append((i, input_file))
        elif file_ending.endswith(DYNAMICLIB_ENDINGS) or shared.Building.is_ar(input_file):
          logging.debug('using library file: ' + input_file)
          temp_files.append((i, input_file))
        elif file_ending.endswith(ASSEMBLY_ENDINGS):
          if not LEAVE_INPUTS_RAW:
            logging.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:
          logging.error(input_file + ': Unknown file suffix when compiling to LLVM bitcode!')
          sys.exit(1)

    log_time('bitcodeize inputs')

    if not LEAVE_INPUTS_RAW:
      assert len(temp_files) == len(input_files)

      # Optimize source files
      if llvm_opts > 0:
        for pos, (_, input_file) in enumerate(input_files):
          file_ending = filename_type_ending(input_file)
          if file_ending.endswith(SOURCE_ENDINGS):
            temp_file = temp_files[pos][1]
            logging.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')
            shared.Building.llvm_opt(temp_file, llvm_opts, new_temp_file)
            temp_files[pos] = (temp_files[pos][0], new_temp_file)

    # Decide what we will link
    linker_inputs = [val for _, val in sorted(temp_files + link_flags)]

    # If we were just asked to generate bitcode, stop there
    if final_suffix not in JS_CONTAINING_SUFFIXES:
      if not specified_target:
        assert len(temp_files) == len(input_files)
        for i in range(len(input_files)):
          safe_move(temp_files[i][1], unsuffixed_basename(input_files[i][1]) + final_ending)
      else:
        if len(input_files) == 1:
          _, input_file = input_files[0]
          _, temp_file = temp_files[0]
          bitcode_target = specified_target if specified_target else unsuffixed_basename(input_file) + final_ending
          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 + 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)
        else:
          assert len(original_input_files) == 1 or not has_dash_c, 'fatal error: cannot specify -o with -c with multiple files' + str(sys.argv) + ':' + str(original_input_files)
          # We have a specified target (-o <target>), which is not JavaScript or HTML, and
          # we have multiple files: Link them
          logging.debug('link: ' + str(linker_inputs) + specified_target)
          # Sort arg tuples and pass the extracted values to link.
          shared.Building.link(linker_inputs, specified_target)
      logging.debug('stopping at bitcode')
      if final_suffix.lower() in ['so', 'dylib', 'dll']:
        logging.warning('Dynamic libraries (.so, .dylib, .dll) are currently not supported by Emscripten. For build system emulation purposes, Emscripten'
          + ' will now generate a static library file (.bc) with the suffix \'.' + final_suffix + '\'. For best practices,'
          + ' please adapt your build system to directly generate a static LLVM bitcode library by setting the output suffix to \'.bc.\')')
      exit(0)

    log_time('process inputs')

    ## Continue on to create JavaScript

    logging.debug('will generate JavaScript')

    extra_files_to_link = []

    if not LEAVE_INPUTS_RAW and \
       not shared.Settings.BUILD_AS_SHARED_LIB and \
       not shared.Settings.BOOTSTRAPPING_STRUCT_INFO and \
       not shared.Settings.ONLY_MY_CODE 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, stderr, forced=forced_stdlibs)

    log_time('calculate system libraries')

    # final will be an array if linking is deferred, otherwise a normal string. 
    DEFAULT_FINAL = in_temp(target_basename + '.bc')
    def get_final():
      global final
      if type(final) != str:
        final = DEFAULT_FINAL
      return final

    # First, combine the bitcode files if there are several. We must also link if we have a singleton .a
    if len(input_files) + len(extra_files_to_link) > 1 or \
       (not LEAVE_INPUTS_RAW and not (suffix(temp_files[0][1]) in BITCODE_ENDINGS or suffix(temp_files[0][1]) in DYNAMICLIB_ENDINGS) and shared.Building.is_ar(temp_files[0][1])):
      linker_inputs += extra_files_to_link
      logging.debug('linking: ' + str(linker_inputs))
      # force archive contents to all be included, if just archives, or if linking shared modules
      force_archive_contents = len([temp for i, temp in temp_files if not temp.endswith(STATICLIB_ENDINGS)]) == 0 or not shared.Building.can_build_standalone()
      just_calculate = DEBUG != '2' # if  EMCC_DEBUG=2 , link now, otherwise defer to be more efficient
      final = shared.Building.link(linker_inputs, DEFAULT_FINAL, force_archive_contents=force_archive_contents, temp_files=misc_temp_files, just_calculate=just_calculate)
    else:
      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)

    log_time('link')

    if DEBUG:
      emscripten_temp_dir = shared.get_emscripten_temp_dir()
      logging.debug('saving intermediate processing steps to %s', emscripten_temp_dir)

      class Intermediate:
        counter = 0
      def save_intermediate(name=None, suffix='js'):
        name = os.path.join(emscripten_temp_dir, 'emcc-%d%s.%s' % (Intermediate.counter, '' if name is None else '-' + name, suffix))
        if type(final) != str:
          logging.debug('(not saving intermediate %s because deferring linking)' % name)
          return
        shutil.copyfile(final, name)
        Intermediate.counter += 1

      if not LEAVE_INPUTS_RAW: save_intermediate('basebc', 'bc')

    # Optimize, if asked to
    if not LEAVE_INPUTS_RAW:
      link_opts = [] if debug_level >= 4 else ['-strip-debug'] # remove LLVM debug if we are not asked for it
      if not shared.Settings.ASSERTIONS:
        link_opts += ['-disable-verify']

      if llvm_lto >= 2 and llvm_opts > 0:
        logging.debug('running LLVM opts as pre-LTO')
        final = shared.Building.llvm_opt(final, llvm_opts, DEFAULT_FINAL)
        if DEBUG: save_intermediate('opt', 'bc')

      # If we can LTO, do it before dce, since it opens up dce opportunities
      if shared.Building.can_build_standalone() and llvm_lto and 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)
        if DEBUG: 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 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')
        if DEBUG: save_intermediate('linktime', 'll')
      else:
        if len(link_opts) > 0:
          final = shared.Building.llvm_opt(final, link_opts, DEFAULT_FINAL)
          if DEBUG: save_intermediate('linktime', 'bc')
        if save_bc:
          shutil.copyfile(final, save_bc)

    # Prepare .ll for Emscripten
    if LEAVE_INPUTS_RAW:
      assert len(input_files) == 1
    if DEBUG and save_bc: save_intermediate('ll', 'll')

    if AUTODEBUG:
      logging.debug('autodebug')
      next = get_final() + '.ad.ll'
      execute([shared.PYTHON, shared.AUTODEBUGGER, final, next])
      final = next
      if DEBUG: save_intermediate('autodebug', 'll')

    assert type(final) == str, 'we must have linked the final files, if linking was deferred, by this point'

    log_time('post-link')

    # Emscripten
    logging.debug('LLVM => JS')
    extra_args = [] if not js_libraries else ['--libraries', ','.join(map(os.path.abspath, js_libraries))]
    if memory_init_file:
      shared.Settings.MEM_INIT_METHOD = 1
    else:
      assert shared.Settings.MEM_INIT_METHOD != 1
    final = shared.Building.emscripten(final, append_ext=False, extra_args=extra_args)
    if DEBUG: save_intermediate('original')

    if shared.Settings.WASM_BACKEND:
      # we also received wasm at this stage
      wasm_temp = final[:-3] + '.wast'
      shutil.move(wasm_temp, wasm_target)
      open(wasm_target + '.mappedGlobals', 'w').write('{}') # no need for mapped globals for now, but perhaps some day

    log_time('emscript (llvm=>%s)' % ('wasm' if shared.Settings.BINARYEN else 'js'))

    # Embed and preload files
    if shared.Settings.SPLIT_MEMORY:
      no_heap_copy = True # copying into the heap is risky when split - the chunks might be too small for the file package!

    if len(preload_files) + len(embed_files) > 0:
      logging.debug('setting up files')
      file_args = []
      if len(preload_files) > 0:
        file_args.append('--preload')
        file_args += preload_files
      if len(embed_files) > 0:
        file_args.append('--embed')
        file_args += embed_files
      if len(exclude_files) > 0:
        file_args.append('--exclude')
        file_args += exclude_files
      if use_preload_cache:
        file_args.append('--use-preload-cache')
      if no_heap_copy:
        file_args.append('--no-heap-copy')
      if not use_closure_compiler:
        file_args.append('--no-closure')
      if shared.Settings.LZ4:
        file_args.append('--lz4')
      if use_preload_plugins:
        file_args.append('--use-preload-plugins')
      file_code = execute([shared.PYTHON, shared.FILE_PACKAGER, unsuffixed(target) + '.data'] + file_args, stdout=PIPE)[0]
      pre_js = file_code + pre_js

    # Apply pre and postjs files
    if pre_js or post_js:
      logging.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 pre_js: pre_js = pre_js.replace('\r\n', '\n')
        if post_js: post_js = post_js.replace('\r\n', '\n')
      open(final, 'w').write(pre_js + src + post_js)
      if DEBUG: save_intermediate('pre-post')

    # Apply a source code transformation, if requested
    if js_transform:
      shutil.copyfile(final, final + '.tr.js')
      final += '.tr.js'
      posix = True if not shared.WINDOWS else False
      logging.debug('applying transform: %s', js_transform)
      subprocess.check_call(shlex.split(js_transform, posix=posix) + [os.path.abspath(final)])
      if DEBUG: save_intermediate('transformed')

    js_transform_tempfiles = [final]

    if shared.Settings.MEM_INIT_METHOD > 0:
      memfile = target + '.mem'
      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 not memory_init_file:
          # memory initializer in a string literal
          return "memoryInitializer = '%s';" % shared.JS.generate_string_initializer(list(membytes))
        open(memfile, 'wb').write(''.join(map(chr, 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)))
        return 'memoryInitializer = "%s";' % os.path.basename(memfile)
      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 DEBUG:
        if os.path.exists(memfile):
          save_intermediate('meminit')
          logging.debug('wrote memory initialization to %s', memfile)
        else:
          logging.debug('did not see memory initialization')
    elif not shared.Settings.MAIN_MODULE and not shared.Settings.SIDE_MODULE and debug_level < 4:
      # not writing a binary init, but we can at least optimize them by splitting them up
      src = open(final).read()
      src = shared.JS.optimize_initializer(src)
      if src is not None:
        logging.debug('optimizing memory initialization')
        open(final + '.mem.js', 'w').write(src)
        final += '.mem.js'
        src = None

    if shared.Settings.USE_PTHREADS:
      shutil.copyfile(shared.path_from_root('src', 'pthread-main.js'), os.path.join(os.path.dirname(os.path.abspath(target)), 'pthread-main.js'))

    if shared.Settings.BINARYEN:
      # Insert a call to integrate with wasm.js
      js = open(final).read()
      js = js.replace('// {{PREAMBLE_ADDITIONS}}', 'integrateWasmJS(Module);\n// {{PREAMBLE_ADDITIONS}}')
      final += '.binaryen.js'
      open(final, 'w').write(js)

    log_time('source transforms')

    # It is useful to run several js optimizer passes together, to save on unneeded unparsing/reparsing
    class JSOptimizer:
      queue = []
      extra_info = {}
      queue_history = []
      blacklist = (os.environ.get('EMCC_JSOPT_BLACKLIST') or '').split(',')
      minify_whitespace = False
      cleanup_shell = False

      @staticmethod
      def flush(title='js_opts'):
        JSOptimizer.queue = filter(lambda p: p not in JSOptimizer.blacklist, JSOptimizer.queue)

        if shared.Settings.WASM_BACKEND:
          logging.debug('ignoring js-optimizer passes since emitting pure wasm: ' + ' '.join(JSOptimizer.queue))
          return

        if JSOptimizer.extra_info is not None and len(JSOptimizer.extra_info) == 0:
          JSOptimizer.extra_info = None

        if len(JSOptimizer.queue) > 0 and not(not shared.Settings.ASM_JS and len(JSOptimizer.queue) == 1 and JSOptimizer.queue[0] == 'last'):

          def run_passes(passes, title, just_split, just_concat):
            global final, target
            passes = ['asm'] + passes
            if shared.Settings.PRECISE_F32:
              passes = ['asmPreciseF32'] + passes
            if emit_symbol_map and 'minifyNames' in passes:
              passes += ['symbolMap='+target+'.symbols']
            if profiling_funcs and 'minifyNames' in passes:
              passes += ['profilingFuncs']
            if JSOptimizer.minify_whitespace and 'last' in passes:
              passes += ['minifyWhitespace']
            if JSOptimizer.cleanup_shell and 'last' in passes:
              passes += ['cleanup']
            logging.debug('applying js optimization passes: %s', ' '.join(passes))
            misc_temp_files.note(final)
            final = shared.Building.js_optimizer(final, passes, debug_level >= 4, JSOptimizer.extra_info, just_split=just_split, just_concat=just_concat)
            misc_temp_files.note(final)
            js_transform_tempfiles.append(final)
            if DEBUG: save_intermediate(title, suffix='js' if 'emitJSON' not in passes else 'json')

          passes = JSOptimizer.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 = shared.js_optimizer.use_native(p, source_map=debug_level >= 4)
                last_native = shared.js_optimizer.use_native(curr[-1], source_map=debug_level >= 4)
                if native == last_native:
                  curr.append(p)
                else:
                  curr.append('emitJSON')
                  chunks.append(curr)
                  curr = ['receiveJSON', p]
            if len(curr) > 0:
              chunks.append(curr)
            if len(chunks) == 1:
              run_passes(chunks[0], title, just_split=False, just_concat=False)
            else:
              for i in range(len(chunks)):
                run_passes(chunks[i], 'js_opts_' + str(i), just_split='receiveJSON' in chunks[i], just_concat='emitJSON' in chunks[i])
          else:
            # DEBUG 2, run each pass separately
            extra_info = JSOptimizer.extra_info
            for p in passes:
              JSOptimizer.queue = [p]
              JSOptimizer.flush(p)
              JSOptimizer.extra_info = extra_info # flush wipes it
              log_time('part of js opts')
          JSOptimizer.queue_history += JSOptimizer.queue
          JSOptimizer.queue = []
        JSOptimizer.extra_info = {}

    if shared.Settings.DEAD_FUNCTIONS:
      JSOptimizer.queue += ['eliminateDeadFuncs']
      JSOptimizer.extra_info['dead_functions'] = shared.Settings.DEAD_FUNCTIONS

    if opt_level >= 1 and js_opts:
      logging.debug('running js post-opts')

      if DEBUG == '2':
        # Clean up the syntax a bit
        JSOptimizer.queue += ['noop']

      def get_eliminate():
        if shared.Settings.ALLOW_MEMORY_GROWTH:
          return 'eliminateMemSafe'
        else:
          return 'eliminate'

      if opt_level >= 2:
        JSOptimizer.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
          JSOptimizer.queue += ['aggressiveVariableElimination']

        JSOptimizer.queue += ['simplifyExpressions']

        if shared.Settings.EMTERPRETIFY:
          # emterpreter code will not run through a JS optimizing JIT, do more work ourselves
          JSOptimizer.queue += ['localCSE']

    if shared.Settings.EMTERPRETIFY:
      # add explicit label setting, as we will run aggressiveVariableElimination late, *after* 'label' is no longer notable by name
      JSOptimizer.queue += ['safeLabelSetting']

    if opt_level >= 1 and js_opts:
      if opt_level >= 2:
        # simplify ifs if it is ok to make the code somewhat unreadable, and unless outlining (simplified ifs
        # with commaified code breaks late aggressive variable elimination)
        if shared.Settings.SIMPLIFY_IFS and (debug_level == 0 or profiling) and shared.Settings.OUTLINING_LIMIT == 0: JSOptimizer.queue += ['simplifyIfs']

        if shared.Settings.PRECISE_F32: JSOptimizer.queue += ['optimizeFrounds']

    def do_minify(): # minifies the code. this is also when we do certain optimizations that must be done right before or after minification
      if shared.Settings.SPLIT_MEMORY: JSOptimizer.queue += ['splitMemory', 'simplifyExpressions'] # must be done before minification

      if opt_level >= 2:
        if debug_level < 2 and not use_closure_compiler == 2:
          JSOptimizer.queue += ['minifyNames']
        if debug_level == 0:
          JSOptimizer.minify_whitespace = True

      if use_closure_compiler == 1:
        JSOptimizer.queue += ['closure']
      elif debug_level <= 2 and shared.Settings.FINALIZE_ASM_JS and not use_closure_compiler:
        JSOptimizer.cleanup_shell = True

    if js_opts:
      if shared.Settings.SAFE_HEAP: JSOptimizer.queue += ['safeHeap']

      if shared.Settings.OUTLINING_LIMIT > 0:
        JSOptimizer.queue += ['outline']
        JSOptimizer.extra_info['sizeToOutline'] = shared.Settings.OUTLINING_LIMIT

      if opt_level >= 2 and debug_level < 3:
        if opt_level >= 3 or shrink_level > 0:
          JSOptimizer.queue += ['registerizeHarder']
        else:
          JSOptimizer.queue += ['registerize']

      # NOTE: Important that this comes after registerize/registerizeHarder
      if shared.Settings.ELIMINATE_DUPLICATE_FUNCTIONS and opt_level >= 2:
        JSOptimizer.flush()
        shared.Building.eliminate_duplicate_funcs(final)

      if not shared.Settings.EMTERPRETIFY:
        do_minify()

      if opt_level >= 2:
        JSOptimizer.queue += ['asmLastOpts']

      if shared.Settings.FINALIZE_ASM_JS: JSOptimizer.queue += ['last']

      JSOptimizer.flush()

    if use_closure_compiler == 2:
      JSOptimizer.flush()

      logging.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=debug_level >= 1)
      if DEBUG: save_intermediate('closure')

    log_time('js opts')

    if shared.Settings.MODULARIZE:
      logging.debug('Modularizing, assigning to var ' + shared.Settings.EXPORT_NAME)
      src = open(final).read()
      final = final + '.modular.js'
      f = open(final, 'w')
      f.write('var ' + shared.Settings.EXPORT_NAME + ' = function(Module) {\n')
      f.write('  Module = Module || {};\n')
      f.write('\n')
      f.write(src)
      f.write('\n')
      f.write('  return Module;\n')
      f.write('};\n')
      f.close()
      src = None

    if shared.Settings.EMTERPRETIFY:
      JSOptimizer.flush()
      logging.debug('emterpretifying')
      import json
      try:
        # move temp js to final position, alongside its mem init file
        shutil.move(final, js_target)
        args = [shared.PYTHON, shared.path_from_root('tools', 'emterpretify.py'), js_target, final + '.em.js', json.dumps(shared.Settings.EMTERPRETIFY_BLACKLIST), json.dumps(shared.Settings.EMTERPRETIFY_WHITELIST), '', str(shared.Settings.SWAPPABLE_ASM_MODULE)]
        if shared.Settings.EMTERPRETIFY_ASYNC:
          args += ['ASYNC=1']
        if shared.Settings.EMTERPRETIFY_ADVISE:
          args += ['ADVISE=1']
        if profiling or 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 + '"']
        execute(args)
        final = final + '.em.js'
      finally:
        shared.try_delete(js_target)

      if shared.Settings.EMTERPRETIFY_ADVISE:
        logging.warning('halting compilation due to EMTERPRETIFY_ADVISE')
        sys.exit(0)

      # minify (if requested) after emterpreter processing, and finalize output
      logging.debug('finalizing emterpreted code')
      shared.Settings.FINALIZE_ASM_JS = 1
      do_minify()
      JSOptimizer.queue += ['last']
      JSOptimizer.flush()

      # 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
        logging.debug('finalizing original (non-emterpreted) code at ' + final)
        do_minify()
        JSOptimizer.queue += ['last']
        JSOptimizer.flush()
        safe_move(final, original)
        final = real

    # 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)

    # Emit source maps, if needed
    if debug_level >= 4:
      logging.debug('generating source maps')
      jsrun.run_js(shared.path_from_root('tools', 'source-maps', 'sourcemapper.js'),
        shared.NODE_JS, js_transform_tempfiles +
          ['--sourceRoot', os.getcwd(),
           '--mapFileBaseName', target,
           '--offset', str(0)])

    # Move final output to the js target
    shutil.move(final, js_target)

    # Separate out the asm.js code, if asked. Or, if necessary for another option
    if (separate_asm or shared.Settings.BINARYEN) and not shared.Settings.WASM_BACKEND:
      temp_target = misc_temp_files.get(suffix='.js').name
      execute([shared.PYTHON, shared.path_from_root('tools', 'separate_asm.py'), js_target, asm_target, temp_target])
      shutil.move(temp_target, js_target)

      # extra only-my-code logic
      if shared.Settings.ONLY_MY_CODE:
        temp = asm_target + '.only.js'
        print jsrun.run_js(shared.path_from_root('tools', 'js-optimizer.js'), shared.NODE_JS, args=[asm_target, 'eliminateDeadGlobals', 'last', 'asm'], stdout=open(temp, 'w'))
        shutil.move(temp, asm_target)

    if shared.Settings.BINARYEN:
      # Emit wasm.js at the top of the js. TODO: for html, it could be a separate script tag
      binaryen_bin = os.path.join(shared.Settings.BINARYEN, 'bin')
      wasm_js = open(os.path.join(binaryen_bin, 'wasm.js')).read()
      wasm_js = wasm_js.replace("Module['asmjsCodeFile']", '"' + os.path.basename(asm_target) + '"') # " or '? who knows :)
      wasm_js = wasm_js.replace('Module["asmjsCodeFile"]', '"' + os.path.basename(asm_target) + '"')
      wasm_js = wasm_js.replace("Module['wasmCodeFile']", '"' + os.path.basename(wasm_target) + '"') # " or '? who knows :)
      wasm_js = wasm_js.replace('Module["wasmCodeFile"]', '"' + os.path.basename(wasm_target) + '"')
      wasm_js = wasm_js.replace("Module['providedTotalMemory']", str(shared.Settings.TOTAL_MEMORY))
      wasm_js = wasm_js.replace('Module["providedTotalMemory"]', str(shared.Settings.TOTAL_MEMORY))
      wasm_js = wasm_js.replace('EMSCRIPTEN_', 'emscripten_') # do not confuse the markers
      if shared.Settings.BINARYEN_METHOD:
        method = '(Module[\'wasmJSMethod\'] || "' + shared.Settings.BINARYEN_METHOD + '")'
        wasm_js = wasm_js.replace("Module['wasmJSMethod']", method) # " or '? who knows :)
        wasm_js = wasm_js.replace('Module["wasmJSMethod"]', method)
      js = open(js_target).read()
      combined = open(js_target, 'w')
      combined.write(wasm_js)
      combined.write('\n//^wasm.js\n')
      combined.write(js)
      combined.close()
      if not shared.Settings.WASM_BACKEND:
        # generate .wast file
        subprocess.check_call([os.path.join(binaryen_bin, 'asm2wasm'), asm_target, '--mapped-globals=' + wasm_target + '.mappedGlobals'], stdout=open(wasm_target, 'w'))

    # If we were asked to also generate HTML, do that
    if final_suffix == 'html':
      logging.debug('generating HTML')
      shell = open(shell_path).read()
      assert '{{{ SCRIPT }}}' in shell, 'HTML shell must contain  {{{ SCRIPT }}}  , see src/shell.html for an example'
      base_js_target = os.path.basename(js_target)

      def un_src(): # use this if you want to modify the script and need it to be inline
        global script_src, script_inline
        if script_src is None: return
        script_inline = '''
          var script = document.createElement('script');
          script.src = "%s";
          document.body.appendChild(script);
''' % script_src
        script_src = None

      asm_mods = []

      if proxy_to_worker:
        child_js = shared.Settings.PROXY_TO_WORKER_FILENAME or target_basename
        script_inline = '''
  if ((',' + window.location.search.substr(1) + ',').indexOf(',noProxy,') < 0) {
    console.log('running code in a web worker');
''' + open(shared.path_from_root('src', 'webGLClient.js')).read() + '\n' + shared.read_and_preprocess(shared.path_from_root('src', 'proxyClient.js')).replace('{{{ filename }}}', child_js).replace('{{{ IDBStore.js }}}', open(shared.path_from_root('src', 'IDBStore.js')).read()) + '''
  } else {
    // note: no support for code mods (PRECISE_F32==2)
    console.log('running code on the main thread');
    var script = document.createElement('script');
    script.src = "%s.js";
    document.body.appendChild(script);
  }
''' % child_js
      else:
        # Normal code generation path
        script_src = base_js_target

        from tools import client_mods
        asm_mods = client_mods.get_mods(shared.Settings, minified = 'minifyNames' in JSOptimizer.queue_history, separate_asm = separate_asm)

      if shared.Settings.EMTERPRETIFY_FILE:
        # We need to load the emterpreter file before anything else, it has to be synchronously ready
        un_src()
        script_inline = '''
          var xhr = new XMLHttpRequest();
          xhr.open('GET', '%s', true);
          xhr.responseType = 'arraybuffer';
          xhr.onload = function() {
            Module.emterpreterFile = xhr.response;
%s
          };
          xhr.send(null);
''' % (shared.Settings.EMTERPRETIFY_FILE, script_inline)

      if memory_init_file:
        # start to load the memory init file in the HTML, in parallel with the JS
        un_src()
        script_inline = ('''
          (function() {
            var memoryInitializer = '%s';
            if (typeof Module['locateFile'] === 'function') {
              memoryInitializer = Module['locateFile'](memoryInitializer);
            } else if (Module['memoryInitializerPrefixURL']) {
              memoryInitializer = Module['memoryInitializerPrefixURL'] + memoryInitializer;
            }
            var xhr = Module['memoryInitializerRequest'] = new XMLHttpRequest();
            xhr.open('GET', memoryInitializer, true);
            xhr.responseType = 'arraybuffer';
            xhr.send(null);
          })();
''' % os.path.basename(memfile)) + script_inline

      if separate_asm:
        un_src()
        if len(asm_mods) == 0:
          # just load the asm, then load the rest
          script_inline = '''
    var script = document.createElement('script');
    script.src = "%s";
    script.onload = function() {
      setTimeout(function() {
        %s
      }, 1); // delaying even 1ms is enough to allow compilation memory to be reclaimed
    };
    document.body.appendChild(script);
''' % (os.path.basename(asm_target), script_inline)
        else:
          # may need to modify the asm code, load it as text, modify, and load asynchronously
          script_inline = '''
    var codeXHR = new XMLHttpRequest();
    codeXHR.open('GET', '%s', true);
    codeXHR.onload = function() {
      var code = codeXHR.responseText;
      %s
      var blob = new Blob([code], { type: 'text/javascript' });
      codeXHR = null;
      var src = URL.createObjectURL(blob);
      var script = document.createElement('script');
      script.src = URL.createObjectURL(blob);
      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);
''' % (os.path.basename(asm_target), '\n'.join(asm_mods), script_inline)
      else:
        assert len(asm_mods) == 0, 'no --separate-asm means no client code mods are possible'

      html = open(target, 'w')
      assert (script_src or script_inline) and not (script_src and script_inline)
      if script_src:
        script_replacement = '<script async type="text/javascript" src="%s"></script>' % script_src
      else:
        script_replacement = '<script>\n%s\n</script>' % script_inline
      html.write(shell.replace('{{{ SCRIPT }}}', script_replacement))
      html.close()
    else: # final_suffix != html
      if proxy_to_worker:
        shutil.move(js_target, js_target[:-3] + '.worker.js') # compiler output goes in .worker.js file
        worker_target_basename = target_basename + '.worker'
        open(target, 'w').write(open(shared.path_from_root('src', 'webGLClient.js')).read() + '\n' + open(shared.path_from_root('src', 'proxyClient.js')).read().replace('{{{ filename }}}', shared.Settings.PROXY_TO_WORKER_FILENAME or worker_target_basename).replace('{{{ IDBStore.js }}}', open(shared.path_from_root('src', 'IDBStore.js')).read()))

    log_time('final emitting')

    if DEBUG: logging.debug('total time: %.2f seconds', (time.time() - start_time))

  finally:
    if not TEMP_DIR:
      try:
        shutil.rmtree(temp_dir)
      except:
        pass
    else:
      logging.info('emcc saved files are in:' + temp_dir)

if __name__ == '__main__':
  run()