path: root/tools/shared.py

import shutil, time, os, sys, json, tempfile, copy, shlex, atexit, subprocess, hashlib, cPickle, re
from subprocess import Popen, PIPE, STDOUT
from tempfile import mkstemp
import jsrun, cache, tempfiles
from response_file import create_response_file

def listify(x):
  if type(x) is not list: return [x]
  return x

# Temp file utilities
from tempfiles import try_delete

# On Windows python suffers from a particularly nasty bug if python is spawning new processes while python itself is spawned from some other non-console process.
# Use a custom replacement for Popen on Windows to avoid the "WindowsError: [Error 6] The handle is invalid" errors when emcc is driven through cmake or mingw32-make. 
# See http://bugs.python.org/issue3905
class WindowsPopen:
  def __init__(self, args, bufsize=0, executable=None, stdin=None, stdout=None, stderr=None, preexec_fn=None, close_fds=False, 
               shell=False, cwd=None, env=None, universal_newlines=False, startupinfo=None, creationflags=0):
    self.stdin = stdin
    self.stdout = stdout
    self.stderr = stderr
    
    # (stdin, stdout, stderr) store what the caller originally wanted to be done with the streams.
    # (stdin_, stdout_, stderr_) will store the fixed set of streams that workaround the bug.
    self.stdin_ = stdin
    self.stdout_ = stdout
    self.stderr_ = stderr
    
    # If the caller wants one of these PIPEd, we must PIPE them all to avoid the 'handle is invalid' bug.
    if self.stdin_ == PIPE or self.stdout_ == PIPE or self.stderr_ == PIPE:
      if self.stdin_ == None:
        self.stdin_ = PIPE
      if self.stdout_ == None:
        self.stdout_ = PIPE
      if self.stderr_ == None:
        self.stderr_ = PIPE

    # emscripten.py supports reading args from a response file instead of cmdline.
    # Use .rsp to avoid cmdline length limitations on Windows.
    if len(args) >= 2 and args[1].endswith("emscripten.py"):
      self.response_filename = create_response_file(args[2:], TEMP_DIR)
      args = args[0:2] + ['@' + self.response_filename]
      
    try:
      # Call the process with fixed streams.
      self.process = subprocess.Popen(args, bufsize, executable, self.stdin_, self.stdout_, self.stderr_, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags)
    except Exception, e:
      print >> sys.stderr, '\nsubprocess.Popen(args=%s) failed! Exception %s\n' % (' '.join(args), str(e))
      raise e

  def communicate(self, input=None):
    output = self.process.communicate(input)
    self.returncode = self.process.returncode

    # If caller never wanted to PIPE stdout or stderr, route the output back to screen to avoid swallowing output.
    if self.stdout == None and self.stdout_ == PIPE and len(output[0].strip()) > 0:
      print >> sys.stdout, output[0]
    if self.stderr == None and self.stderr_ == PIPE and len(output[1].strip()) > 0:
      print >> sys.stderr, output[1]

    # Return a mock object to the caller. This works as long as all emscripten code immediately .communicate()s the result, and doesn't
    # leave the process object around for longer/more exotic uses.
    if self.stdout == None and self.stderr == None:
      return (None, None)
    if self.stdout == None:
      return (None, output[1])
    if self.stderr == None:
      return (output[0], None)
    return (output[0], output[1])

  def poll(self):
    return self.process.poll()

  def kill(self):
    return self.process.kill()
  
  def __del__(self):
    try:
      # Clean up the temporary response file that was used to spawn this process, so that we don't leave temp files around.
      tempfiles.try_delete(self.response_filename)
    except:
      pass # Mute all exceptions in dtor, particularly if we didn't use a response file, self.response_filename doesn't exist.

# Install our replacement Popen handler if we are running on Windows to avoid python spawn process function.
if os.name == 'nt':
  Popen = WindowsPopen

__rootpath__ = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
def path_from_root(*pathelems):
  return os.path.join(__rootpath__, *pathelems)

# Emscripten configuration is done through the EM_CONFIG environment variable.
# If the string value contained in this environment variable contains newline
# separated definitions, then these definitions will be used to configure
# Emscripten.  Otherwise, the string is understood to be a path to a settings
# file that contains the required definitions.

EM_CONFIG = os.environ.get('EM_CONFIG')
if not EM_CONFIG:
  EM_CONFIG = '~/.emscripten'
if '\n' in EM_CONFIG:
  CONFIG_FILE = None
else:
  CONFIG_FILE = os.path.expanduser(EM_CONFIG)
  if not os.path.exists(CONFIG_FILE):
    config_file = open(path_from_root('tools', 'settings_template_readonly.py')).read().split('\n')
    config_file = config_file[1:] # remove "this file will be copied..."
    config_file = '\n'.join(config_file)
    # autodetect some default paths
    config_file = config_file.replace('{{{ EMSCRIPTEN_ROOT }}}', __rootpath__)
    llvm_root = '/usr/bin'
    try:
      llvm_root = os.path.dirname(Popen(['which', 'clang'], stdout=PIPE).communicate()[0].replace('\n', ''))
    except:
      pass
    config_file = config_file.replace('{{{ LLVM_ROOT }}}', llvm_root)
    node = 'node'
    try:
      node = Popen(['which', 'node'], stdout=PIPE).communicate()[0].replace('\n', '') or \
             Popen(['which', 'nodejs'], stdout=PIPE).communicate()[0].replace('\n', '') or node
    except:
      pass
    config_file = config_file.replace('{{{ NODE }}}', node)
    python = 'python'
    try:
      python = Popen(['which', 'python'], stdout=PIPE).communicate()[0].replace('\n', '')
    except:
      pass
    config_file = config_file.replace('{{{ PYTHON }}}', python)    

    # write
    open(CONFIG_FILE, 'w').write(config_file)
    print >> sys.stderr, '''
==============================================================================
Welcome to Emscripten!

This is the first time any of the Emscripten tools has been run.

A settings file has been copied to %s, at absolute path: %s

It contains our best guesses for the important paths, which are:

  LLVM_ROOT       = %s
  PYTHON          = %s
  NODE_JS         = %s
  EMSCRIPTEN_ROOT = %s

Please edit the file if any of those are incorrect.

This command will now exit. When you are done editing those paths, re-run it.
==============================================================================
''' % (EM_CONFIG, CONFIG_FILE, llvm_root, python, node, __rootpath__)
    sys.exit(0)
try:
  config_text = open(CONFIG_FILE, 'r').read() if CONFIG_FILE else EM_CONFIG
  exec(config_text)
except Exception, e:
  print >> sys.stderr, 'Error in evaluating %s (at %s): %s, text: %s' % (EM_CONFIG, CONFIG_FILE, str(e), config_text)
  sys.exit(1)

# Expectations

EXPECTED_LLVM_VERSION = (3,2)

def check_clang_version():
  expected = 'clang version ' + '.'.join(map(str, EXPECTED_LLVM_VERSION))
  actual = Popen([CLANG, '-v'], stderr=PIPE).communicate()[1].split('\n')[0]
  if expected in actual:
    return True
  print >> sys.stderr, 'warning: LLVM version appears incorrect (seeing "%s", expected "%s")' % (actual, expected)
  return False

def check_llvm_version():
  try:
    check_clang_version();
  except Exception, e:
    print >> sys.stderr, 'warning: Could not verify LLVM version: %s' % str(e)

EXPECTED_NODE_VERSION = (0,6,8)

def check_node_version():
  try:
    node = listify(NODE_JS)
    actual = Popen(node + ['--version'], stdout=PIPE).communicate()[0].strip()
    version = tuple(map(int, actual.replace('v', '').split('.')))
    if version >= EXPECTED_NODE_VERSION:
      return True
    print >> sys.stderr, 'warning: node version appears too old (seeing "%s", expected "%s")' % (actual, 'v' + ('.'.join(map(str, EXPECTED_NODE_VERSION))))
    return False
  except Exception, e:
    print >> sys.stderr, 'warning: cannot check node version:', e
    return False

# Check that basic stuff we need (a JS engine to compile, Node.js, and Clang and LLVM)
# exists.
# The test runner always does this check (through |force|). emcc does this less frequently,
# only when ${EM_CONFIG}_sanity does not exist or is older than EM_CONFIG (so,
# we re-check sanity when the settings are changed)
# We also re-check sanity and clear the cache when the version changes

EMSCRIPTEN_VERSION = '1.3.7'

def check_sanity(force=False):
  try:
    if not force:
      if not CONFIG_FILE:
        return # config stored directly in EM_CONFIG => skip sanity checks
      settings_mtime = os.stat(CONFIG_FILE).st_mtime
      sanity_file = CONFIG_FILE + '_sanity'
      reason = 'unknown'
      try:
        sanity_mtime = os.stat(sanity_file).st_mtime
        if sanity_mtime <= settings_mtime:
          reason = 'settings file has changed'
        else:
          sanity_version = open(sanity_file).read()
          if sanity_version != EMSCRIPTEN_VERSION:
            reason = 'version bump'
          else:
            return # all is well
      except:
        pass

      print >> sys.stderr, '(Emscripten: %s, clearing cache)' % reason
      Cache.erase()

    # some warning, not fatal checks - do them even if EM_IGNORE_SANITY is on
    check_llvm_version()
    check_node_version()

    if os.environ.get('EM_IGNORE_SANITY'):
      print >> sys.stderr, 'EM_IGNORE_SANITY set, ignoring sanity checks'
      return

    print >> sys.stderr, '(Emscripten: Running sanity checks)'

    if not check_engine(COMPILER_ENGINE):
      print >> sys.stderr, 'FATAL: The JavaScript shell used for compiling (%s) does not seem to work, check the paths in %s' % (COMPILER_ENGINE, EM_CONFIG)
      sys.exit(1)

    if NODE_JS != COMPILER_ENGINE:
      if not check_engine(NODE_JS):
        print >> sys.stderr, 'FATAL: Node.js (%s) does not seem to work, check the paths in %s' % (NODE_JS, EM_CONFIG)
        sys.exit(1)

    for cmd in [CLANG, LLVM_LINK, LLVM_AR, LLVM_OPT, LLVM_AS, LLVM_DIS, LLVM_NM]:
      if not os.path.exists(cmd) and not os.path.exists(cmd + '.exe'): # .exe extension required for Windows
        print >> sys.stderr, 'FATAL: Cannot find %s, check the paths in %s' % (cmd, EM_CONFIG)
        sys.exit(1)

    try:
      subprocess.call([JAVA, '-version'], stdout=PIPE, stderr=PIPE)
    except:
      print >> sys.stderr, 'WARNING: java does not seem to exist, required for closure compiler. -O2 and above will fail. You need to define JAVA in ~/.emscripten'

    if not os.path.exists(CLOSURE_COMPILER):
      print >> sys.stderr, 'WARNING: Closure compiler (%s) does not exist, check the paths in %s. -O2 and above will fail' % (CLOSURE_COMPILER, EM_CONFIG)

    # Sanity check passed!

    if not force:
      # Only create/update this file if the sanity check succeeded, i.e., we got here
      f = open(sanity_file, 'w')
      f.write(EMSCRIPTEN_VERSION)
      f.close()

  except Exception, e:
    # Any error here is not worth failing on
    print 'WARNING: sanity check failed to run', e

# Tools/paths

LLVM_ADD_VERSION = os.getenv('LLVM_ADD_VERSION')
CLANG_ADD_VERSION = os.getenv('CLANG_ADD_VERSION')

# Some distributions ship with multiple llvm versions so they add
# the version to the binaries, cope with that
def build_llvm_tool_path(tool):
  if LLVM_ADD_VERSION:
    return os.path.join(LLVM_ROOT, tool + "-" + LLVM_ADD_VERSION)
  else:
    return os.path.join(LLVM_ROOT, tool)

# Some distributions ship with multiple clang versions so they add
# the version to the binaries, cope with that
def build_clang_tool_path(tool):
  if CLANG_ADD_VERSION:
    return os.path.join(LLVM_ROOT, tool + "-" + CLANG_ADD_VERSION)
  else:
    return os.path.join(LLVM_ROOT, tool)

CLANG_CC=os.path.expanduser(build_clang_tool_path('clang'))
CLANG_CPP=os.path.expanduser(build_clang_tool_path('clang++'))
CLANG=CLANG_CPP
LLVM_LINK=build_llvm_tool_path('llvm-link')
LLVM_AR=build_llvm_tool_path('llvm-ar')
LLVM_OPT=os.path.expanduser(build_llvm_tool_path('opt'))
LLVM_AS=os.path.expanduser(build_llvm_tool_path('llvm-as'))
LLVM_DIS=os.path.expanduser(build_llvm_tool_path('llvm-dis'))
LLVM_NM=os.path.expanduser(build_llvm_tool_path('llvm-nm'))
LLVM_INTERPRETER=os.path.expanduser(build_llvm_tool_path('lli'))
LLVM_COMPILER=os.path.expanduser(build_llvm_tool_path('llc'))

EMSCRIPTEN = path_from_root('emscripten.py')
DEMANGLER = path_from_root('third_party', 'demangler.py')
NAMESPACER = path_from_root('tools', 'namespacer.py')
EMCC = path_from_root('emcc')
EMXX = path_from_root('em++')
EMAR = path_from_root('emar')
EMRANLIB = path_from_root('emranlib')
EMLIBTOOL = path_from_root('emlibtool')
EMCONFIG = path_from_root('em-config')
EMMAKEN = path_from_root('tools', 'emmaken.py')
AUTODEBUGGER = path_from_root('tools', 'autodebugger.py')
BINDINGS_GENERATOR = path_from_root('tools', 'bindings_generator.py')
EXEC_LLVM = path_from_root('tools', 'exec_llvm.py')
FILE_PACKAGER = path_from_root('tools', 'file_packager.py')

# Temp dir. Create a random one, unless EMCC_DEBUG is set, in which case use TEMP_DIR/emscripten_temp

class Configuration:
  def __init__(self, environ):
    self.DEBUG = environ.get('EMCC_DEBUG')
    if self.DEBUG == "0":
      self.DEBUG = None
    self.DEBUG_CACHE = self.DEBUG and "cache" in self.DEBUG
    self.EMSCRIPTEN_TEMP_DIR = None

    try:
      self.TEMP_DIR = TEMP_DIR
    except NameError:
      print >> sys.stderr, 'TEMP_DIR not defined in ~/.emscripten, using /tmp'
      self.TEMP_DIR = '/tmp'

    self.CANONICAL_TEMP_DIR = os.path.join(self.TEMP_DIR, 'emscripten_temp')

    if self.DEBUG:
      try:
        self.EMSCRIPTEN_TEMP_DIR = self.CANONICAL_TEMP_DIR
        if not os.path.exists(self.EMSCRIPTEN_TEMP_DIR):
          os.makedirs(self.EMSCRIPTEN_TEMP_DIR)
      except Exception, e:
        print >> sys.stderr, e, 'Could not create canonical temp dir. Check definition of TEMP_DIR in ~/.emscripten'

  def get_temp_files(self):
    return tempfiles.TempFiles(
      tmp=self.TEMP_DIR if not self.DEBUG else self.EMSCRIPTEN_TEMP_DIR,
      save_debug_files=os.environ.get('EMCC_DEBUG_SAVE'))

  def debug_log(self, msg):
    if self.DEBUG:
      print >> sys.stderr, msg

configuration = Configuration(environ=os.environ)
DEBUG = configuration.DEBUG
EMSCRIPTEN_TEMP_DIR = configuration.EMSCRIPTEN_TEMP_DIR
DEBUG_CACHE = configuration.DEBUG_CACHE
CANONICAL_TEMP_DIR = configuration.CANONICAL_TEMP_DIR

if not EMSCRIPTEN_TEMP_DIR:
  EMSCRIPTEN_TEMP_DIR = tempfile.mkdtemp(prefix='emscripten_temp_', dir=configuration.TEMP_DIR)
  def clean_temp():
    try_delete(EMSCRIPTEN_TEMP_DIR)
  atexit.register(clean_temp)

# EM_CONFIG stuff

try:
  JS_ENGINES
except:
  try:
    JS_ENGINES = [JS_ENGINE]
  except Exception, e:
    print 'ERROR: %s does not seem to have JS_ENGINES or JS_ENGINE set up' % EM_CONFIG
    raise

try:
  CLOSURE_COMPILER
except:
  CLOSURE_COMPILER = path_from_root('third_party', 'closure-compiler', 'compiler.jar')

try:
  PYTHON
except:
  if DEBUG: print >> sys.stderr, 'PYTHON not defined in ~/.emscripten, using "python"'
  PYTHON = 'python'

try:
  JAVA
except:
  if DEBUG: print >> sys.stderr, 'JAVA not defined in ~/.emscripten, using "java"'
  JAVA = 'java'

# Additional compiler options

try:
  COMPILER_OPTS # Can be set in EM_CONFIG, optionally
except:
  COMPILER_OPTS = []
# Force a simple, standard target as much as possible: target 32-bit linux, and disable various flags that hint at other platforms
COMPILER_OPTS = COMPILER_OPTS + ['-m32', '-U__i386__', '-U__i386', '-Ui386',
                                 '-U__SSE__', '-U__SSE_MATH__', '-U__SSE2__', '-U__SSE2_MATH__', '-U__MMX__',
                                 '-DEMSCRIPTEN', '-U__STRICT_ANSI__',
                                 '-target', 'i386-pc-linux-gnu', '-D__IEEE_LITTLE_ENDIAN', '-fno-math-errno']

USE_EMSDK = not os.environ.get('EMMAKEN_NO_SDK')

if USE_EMSDK:
  # Disable system C and C++ include directories, and add our own (using -idirafter so they are last, like system dirs, which
  # allows projects to override them)
  EMSDK_OPTS = ['-nostdinc', '-nostdinc++', '-Xclang', '-nobuiltininc', '-Xclang', '-nostdsysteminc',
    '-Xclang', '-isystem' + path_from_root('system', 'local', 'include'),
    '-Xclang', '-isystem' + path_from_root('system', 'include', 'libcxx'),
    '-Xclang', '-isystem' + path_from_root('system', 'include'),
    '-Xclang', '-isystem' + path_from_root('system', 'include', 'emscripten'),
    '-Xclang', '-isystem' + path_from_root('system', 'include', 'bsd'), # posix stuff
    '-Xclang', '-isystem' + path_from_root('system', 'include', 'libc'),
    '-Xclang', '-isystem' + path_from_root('system', 'include', 'gfx'),
    '-Xclang', '-isystem' + path_from_root('system', 'include', 'net'),
    '-Xclang', '-isystem' + path_from_root('system', 'include', 'SDL'),
  ] + [
    '-U__APPLE__', '-U__linux__'
  ]
  COMPILER_OPTS += EMSDK_OPTS
else:
  EMSDK_OPTS = []

#print >> sys.stderr, 'SDK opts', ' '.join(EMSDK_OPTS)
#print >> sys.stderr, 'Compiler opts', ' '.join(COMPILER_OPTS)

# Engine tweaks

try:
  if 'gcparam' not in str(SPIDERMONKEY_ENGINE):
    if type(SPIDERMONKEY_ENGINE) is str:
      SPIDERMONKEY_ENGINE = [SPIDERMONKEY_ENGINE]
    SPIDERMONKEY_ENGINE += ['-e', "gcparam('maxBytes', 1024*1024*1024);"] # Our very large files need lots of gc heap
except NameError:
  pass

WINDOWS = sys.platform.startswith('win')

# If we have 'env', we should use that to find python, because |python| may fail while |env python| may work
# (For example, if system python is 3.x while we need 2.x, and env gives 2.x if told to do so.)
ENV_PREFIX = []
if not WINDOWS:
  try:
    assert 'Python' in Popen(['env', 'python', '-V'], stdout=PIPE, stderr=STDOUT).communicate()[0]
    ENV_PREFIX = ['env']
  except:
    pass

# Utilities

def check_engine(engine):
  # TODO: we call this several times, perhaps cache the results?
  try:
    if not CONFIG_FILE:
      return True # config stored directly in EM_CONFIG => skip engine check
    return 'hello, world!' in run_js(path_from_root('tests', 'hello_world.js'), engine)
  except Exception, e:
    print 'Checking JS engine %s failed. Check %s. Details: %s' % (str(engine), EM_CONFIG, str(e))
    return False

def run_js(filename, engine=None, *args, **kw):
  if engine is None:
    engine = JS_ENGINES[0]
  return jsrun.run_js(filename, engine, *args, **kw)

def to_cc(cxx):
  # By default, LLVM_GCC and CLANG are really the C++ versions. This gets an explicit C version
  return cxx.replace('clang++', 'clang').replace('g++', 'gcc')

def line_splitter(data):
  """Silly little tool to split JSON arrays over many lines."""

  out = ''
  counter = 0

  for i in range(len(data)):
    out += data[i]
    if data[i] == ' ' and counter > 60:
      out += '\n'
      counter = 0
    else:
      counter += 1

  return out

def limit_size(string, MAX=80*20):
  if len(string) < MAX: return string
  return string[0:MAX/2] + '\n[..]\n' + string[-MAX/2:]

def read_pgo_data(filename):
  '''
    Reads the output of PGO and generates proper information for CORRECT_* == 2 's *_LINES options
  '''
  signs_lines = []
  overflows_lines = []

  for line in open(filename, 'r'):
    try:
      if line.rstrip() == '': continue
      if '%0 failures' in line: continue
      left, right = line.split(' : ')
      signature = left.split('|')[1]
      if 'Sign' in left:
        signs_lines.append(signature)
      elif 'Overflow' in left:
        overflows_lines.append(signature)
    except:
      pass

  return {
    'signs_lines': signs_lines,
    'overflows_lines': overflows_lines
  }

def unique_ordered(values): # return a list of unique values in an input list, without changing order (list(set(.)) would change order randomly)
  seen = set()
  def check(value):
    if value in seen: return False
    seen.add(value)
    return True
  return filter(check, values)

# Settings. A global singleton. Not pretty, but nicer than passing |, settings| everywhere

class Settings:
  @classmethod
  def reset(self):
    class Settings2:
      QUANTUM_SIZE = 4
      reset = Settings.reset

      # Given some emcc-type args (-O3, -s X=Y, etc.), fill Settings with the right settings
      @classmethod
      def load(self, args=[]):
        # Load the JS defaults into python
        settings = open(path_from_root('src', 'settings.js')).read().replace('var ', 'Settings.').replace('//', '#')
        exec settings in globals()

        # Apply additional settings. First -O, then -s
        for i in range(len(args)):
          if args[i].startswith('-O'):
            level = eval(args[i][2])
            Settings.apply_opt_level(level)
        for i in range(len(args)):
          if args[i] == '-s':
            exec 'Settings.' + args[i+1] in globals() # execute the setting

      # Transforms the Settings information into emcc-compatible args (-s X=Y, etc.). Basically
      # the reverse of load_settings, except for -Ox which is relevant there but not here
      @classmethod
      def serialize(self):
        ret = []
        for key, value in Settings.__dict__.iteritems():
          if key == key.upper(): # this is a hack. all of our settings are ALL_CAPS, python internals are not
            jsoned = json.dumps(value, sort_keys=True)
            ret += ['-s', key + '=' + jsoned]
        return ret

      @classmethod
      def apply_opt_level(self, opt_level, noisy=False):
        if opt_level >= 1:
          Settings.ASM_JS = 1
          Settings.ASSERTIONS = 0
          Settings.DISABLE_EXCEPTION_CATCHING = 1
          Settings.EMIT_GENERATED_FUNCTIONS = 1
        if opt_level >= 2:
          Settings.RELOOP = 1
        if opt_level >= 3:
          # Aside from these, -O3 also runs closure compiler and llvm lto
          Settings.DOUBLE_MODE = 0
          Settings.PRECISE_I64_MATH = 0
          if noisy: print >> sys.stderr, 'Warning: Applying some potentially unsafe optimizations! (Use -O2 if this fails.)'

    global Settings
    Settings = Settings2
    Settings.load() # load defaults

Settings.reset()

# Building

class Building:
  COMPILER = CLANG
  LLVM_OPTS = False
  COMPILER_TEST_OPTS = [] # For use of the test runner

  @staticmethod
  def get_building_env(native=False):
    env = os.environ.copy()
    if native:
      env['CC'] = CLANG_CC
      env['CXX'] = CLANG_CPP
      env['LD'] = CLANG
      env['CFLAGS'] = '-O2 -fno-math-errno'
      return env
    env['CC'] = EMCC if not WINDOWS else 'python %r' % EMCC
    env['CXX'] = EMXX if not WINDOWS else 'python %r' % EMXX
    env['AR'] = EMAR if not WINDOWS else 'python %r' % EMAR
    env['LD'] = EMCC if not WINDOWS else 'python %r' % EMCC
    env['LDSHARED'] = EMCC if not WINDOWS else 'python %r' % EMCC
    env['RANLIB'] = EMRANLIB if not WINDOWS else 'python %r' % EMRANLIB
    #env['LIBTOOL'] = EMLIBTOOL if not WINDOWS else 'python %r' % EMLIBTOOL
    env['EMMAKEN_COMPILER'] = Building.COMPILER
    env['EMSCRIPTEN_TOOLS'] = path_from_root('tools')
    env['CFLAGS'] = env['EMMAKEN_CFLAGS'] = ' '.join(Building.COMPILER_TEST_OPTS)
    env['HOST_CC'] = CLANG_CC
    env['HOST_CXX'] = CLANG_CPP
    env['HOST_CFLAGS'] = "-W" #if set to nothing, CFLAGS is used, which we don't want
    env['HOST_CXXFLAGS'] = "-W" #if set to nothing, CXXFLAGS is used, which we don't want
    env['PKG_CONFIG_LIBDIR'] = path_from_root('system', 'local', 'lib', 'pkgconfig') + os.path.pathsep + path_from_root('system', 'lib', 'pkgconfig')
    env['PKG_CONFIG_PATH'] = os.environ.get ('EM_PKG_CONFIG_PATH') or ''
    return env

  @staticmethod
  def handle_CMake_toolchain(args, env):
    CMakeToolchain = ('''# the name of the target operating system
SET(CMAKE_SYSTEM_NAME Linux)

# which C and C++ compiler to use
SET(CMAKE_C_COMPILER   %(winfix)s$EMSCRIPTEN_ROOT/emcc)
SET(CMAKE_CXX_COMPILER %(winfix)s$EMSCRIPTEN_ROOT/em++)
SET(CMAKE_AR           %(winfix)s$EMSCRIPTEN_ROOT/emar)
SET(CMAKE_RANLIB       %(winfix)s$EMSCRIPTEN_ROOT/emranlib)
SET(CMAKE_C_FLAGS      $CFLAGS)
SET(CMAKE_CXX_FLAGS    $CXXFLAGS)

# here is the target environment located
SET(CMAKE_FIND_ROOT_PATH  $EMSCRIPTEN_ROOT/system/include )

# adjust the default behaviour of the FIND_XXX() commands:
# search headers and libraries in the target environment, search
# programs in the host environment
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE BOTH)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)''' % { 'winfix': '' if not WINDOWS else 'python ' }) \
      .replace('$EMSCRIPTEN_ROOT', path_from_root('').replace('\\', '/')) \
      .replace('$CFLAGS', env['CFLAGS']) \
      .replace('$CXXFLAGS', env['CFLAGS'])
    toolchainFile = mkstemp(suffix='.cmaketoolchain.txt', dir=configuration.TEMP_DIR)[1]
    open(toolchainFile, 'w').write(CMakeToolchain)
    args.append('-DCMAKE_TOOLCHAIN_FILE=%s' % os.path.abspath(toolchainFile))
    return args

  @staticmethod
  def configure(args, stdout=None, stderr=None, env=None):
    if not args:
      return
    if env is None:
      env = Building.get_building_env()
    env['EMMAKEN_JUST_CONFIGURE'] = '1'
    if 'cmake' in args[0]:
      args = Building.handle_CMake_toolchain(args, env)
    try:
      Popen(args, stdout=stdout, stderr=stderr, env=env).communicate()
    except Exception, e:
      print >> sys.stderr, 'Error: Exception thrown when invoking Popen in configure with args: "%s"!' % ' '.join(args)
      raise
    del env['EMMAKEN_JUST_CONFIGURE']

  @staticmethod
  def make(args, stdout=None, stderr=None, env=None):
    if env is None:
      env = Building.get_building_env()
    if not args:
      print >> sys.stderr, 'Error: Executable to run not specified.'
      sys.exit(1)
    #args += ['VERBOSE=1']
    try:
      Popen(args, stdout=stdout, stderr=stderr, env=env).communicate()
    except Exception, e:
      print >> sys.stderr, 'Error: Exception thrown when invoking Popen in make with args: "%s"!' % ' '.join(args)
      raise

  @staticmethod
  def build_library(name, build_dir, output_dir, generated_libs, configure=['sh', './configure'], configure_args=[], make=['make'], make_args=['-j', '2'], cache=None, cache_name=None, copy_project=False, env_init={}, source_dir=None, native=False):
    ''' Build a library into a .bc file. We build the .bc file once and cache it for all our tests. (We cache in
        memory since the test directory is destroyed and recreated for each test. Note that we cache separately
        for different compilers).
        This cache is just during the test runner. There is a different concept of caching as well, see |Cache|. '''

    if type(generated_libs) is not list: generated_libs = [generated_libs]
    if source_dir is None: source_dir = path_from_root('tests', name.replace('_native', ''))

    temp_dir = build_dir
    if copy_project:
      project_dir = os.path.join(temp_dir, name)
      if os.path.exists(project_dir):
        shutil.rmtree(project_dir)
      shutil.copytree(source_dir, project_dir) # Useful in debugging sometimes to comment this out, and two lines above
    else:
      project_dir = build_dir
    try:
      old_dir = os.getcwd()
    except:
      old_dir = None
    os.chdir(project_dir)
    generated_libs = map(lambda lib: os.path.join(project_dir, lib), generated_libs)
    #for lib in generated_libs:
    #  try:
    #    os.unlink(lib) # make sure compilation completed successfully
    #  except:
    #    pass
    env = Building.get_building_env(native)
    for k, v in env_init.iteritems():
      env[k] = v
    if configure: # Useful in debugging sometimes to comment this out (and the lines below up to and including the |link| call)
      Building.configure(configure + configure_args, stdout=open(os.path.join(project_dir, 'configure_'), 'w'),
                                                     stderr=open(os.path.join(project_dir, 'configure_err'), 'w'), env=env)
    def open_make_out(i, mode='r'):
      return open(os.path.join(project_dir, 'make_' + str(i)), mode)
    
    def open_make_err(i, mode='r'):
      return open(os.path.join(project_dir, 'make_err' + str(i)), mode)
    
    for i in range(2): # FIXME: Sad workaround for some build systems that need to be run twice to succeed (e.g. poppler)
      with open_make_out(i, 'w') as make_out:
        with open_make_err(i, 'w') as make_err:
          Building.make(make + make_args, stdout=make_out,
                                          stderr=make_err, env=env)
      try:
        if cache is not None:
          cache[cache_name] = []
          for f in generated_libs:
            basename = os.path.basename(f)
            cache[cache_name].append((basename, open(f, 'rb').read()))
        break
      except Exception, e:
        if i > 0:
          # Due to the ugly hack above our best guess is to output the first run
          with open_make_err(0) as ferr:
            for line in ferr:
              sys.stderr.write(line)
          raise Exception('could not build library ' + name + ' due to exception ' + str(e))
    if old_dir:
      os.chdir(old_dir)
    return generated_libs

  @staticmethod
  def link(files, target):
    actual_files = []
    unresolved_symbols = set(['main']) # tracking unresolveds is necessary for .a linking, see below. (and main is always a necessary symbol)
    resolved_symbols = set()
    temp_dirs = []
    files = map(os.path.abspath, files)
    has_ar = False
    for f in files:
      has_ar = has_ar or Building.is_ar(f)
    for f in files:
      if not Building.is_ar(f):
        if Building.is_bitcode(f):
          if has_ar:
            new_symbols = Building.llvm_nm(f)
            resolved_symbols = resolved_symbols.union(new_symbols.defs)
            unresolved_symbols = unresolved_symbols.union(new_symbols.undefs.difference(resolved_symbols)).difference(new_symbols.defs)
          actual_files.append(f)
      else:
        # Extract object files from ar archives, and link according to gnu ld semantics
        # (link in an entire .o from the archive if it supplies symbols still unresolved)
        cwd = os.getcwd()
        try:
          temp_dir = os.path.join(EMSCRIPTEN_TEMP_DIR, 'ar_output_' + str(os.getpid()) + '_' + str(len(temp_dirs)))
          temp_dirs.append(temp_dir)
          if not os.path.exists(temp_dir):
            os.makedirs(temp_dir)
          os.chdir(temp_dir)
          contents = filter(lambda x: len(x) > 0, Popen([LLVM_AR, 't', f], stdout=PIPE).communicate()[0].split('\n'))
          #print >> sys.stderr, '  considering archive', f, ':', contents
          if len(contents) == 0:
            print >> sys.stderr, 'Warning: Archive %s appears to be empty (recommendation: link an .so instead of .a)' % f
          else:
            for content in contents: # ar will silently fail if the directory for the file does not exist, so make all the necessary directories
              dirname = os.path.dirname(content)
              if dirname and not os.path.exists(dirname):
                os.makedirs(dirname)
            Popen([LLVM_AR, 'x', f], stdout=PIPE).communicate() # if absolute paths, files will appear there. otherwise, in this directory
            contents = map(lambda content: os.path.join(temp_dir, content), contents)
            contents = filter(os.path.exists, map(os.path.abspath, contents))
            added_contents = set()
            added = True
            #print >> sys.stderr, '  initial undef are now ', unresolved_symbols, '\n'
            while added: # recursively traverse until we have everything we need
              #print >> sys.stderr, '  running loop of archive including for', f
              added = False
              for content in contents:
                if content in added_contents: continue 
                new_symbols = Building.llvm_nm(content)
                # Link in the .o if it provides symbols, *or* this is a singleton archive (which is apparently an exception in gcc ld)
                #print >> sys.stderr, 'need', content, '?', unresolved_symbols, 'and we can supply', new_symbols.defs
                #print >> sys.stderr, content, 'DEF', new_symbols.defs, '\n'
                if new_symbols.defs.intersection(unresolved_symbols) or len(files) == 1:
                  if Building.is_bitcode(content):
                    #print >> sys.stderr, '  adding object', content, '\n'
                    resolved_symbols = resolved_symbols.union(new_symbols.defs)
                    unresolved_symbols = unresolved_symbols.union(new_symbols.undefs.difference(resolved_symbols)).difference(new_symbols.defs)
                    #print >> sys.stderr, '  undef are now ', unresolved_symbols, '\n'
                    actual_files.append(content)
                    added_contents.add(content)
                    added = True
            #print >> sys.stderr, '  done running loop of archive including for', f
        finally:
          os.chdir(cwd)
    try_delete(target)

    # Finish link
    actual_files = unique_ordered(actual_files) # tolerate people trying to link a.so a.so etc.
    if DEBUG: print >>sys.stderr, 'emcc: llvm-linking:', actual_files

    # check for too-long command line
    link_cmd = [LLVM_LINK] + actual_files + ['-o', target]
    # 8k is a bit of an arbitrary limit, but a reasonable one
    # for max command line size before we use a respose file
    response_file = None
    if WINDOWS and len(' '.join(link_cmd)) > 8192:
      if DEBUG: print >>sys.stderr, 'using response file for llvm-link'
      [response_fd, response_file] = mkstemp(suffix='.response', dir=TEMP_DIR)

      link_cmd = [LLVM_LINK, "@" + response_file]

      response_fh = os.fdopen(response_fd, 'w')
      for arg in actual_files:
        # we can't put things with spaces in the response file
        if " " in arg:
          link_cmd.append(arg)
        else:
          response_fh.write(arg + "\n")
      response_fh.close()
      link_cmd.append("-o")
      link_cmd.append(target)

      if len(' '.join(link_cmd)) > 8192:
        print >>sys.stderr, 'emcc: warning: link command line is very long, even with response file -- use paths with no spaces'

    output = Popen(link_cmd, stdout=PIPE).communicate()[0]

    if response_file:
      os.unlink(response_file)

    assert os.path.exists(target) and (output is None or 'Could not open input file' not in output), 'Linking error: ' + output
    for temp_dir in temp_dirs:
      try_delete(temp_dir)

  # Emscripten optimizations that we run on the .ll file
  @staticmethod
  def ll_opts(filename):
    ## Remove target info. This helps LLVM opts, if we run them later
    #cleaned = filter(lambda line: not line.startswith('target datalayout = ') and not line.startswith('target triple = '),
    #                 open(filename + '.o.ll', 'r').readlines())
    #os.unlink(filename + '.o.ll')
    #open(filename + '.o.ll.orig', 'w').write(''.join(cleaned))
    pass

  # LLVM optimizations
  # @param opt Either an integer, in which case it is the optimization level (-O1, -O2, etc.), or a list of raw
  #            optimization passes passed to llvm opt
  @staticmethod
  def llvm_opt(filename, opts):
    if type(opts) is int:
      opts = Building.pick_llvm_opts(opts)
    #opts += ['-debug-pass=Arguments']
    if DEBUG: print >> sys.stderr, 'emcc: LLVM opts:', opts
    output = Popen([LLVM_OPT, filename] + opts + ['-o=' + filename + '.opt.bc'], stdout=PIPE).communicate()[0]
    assert os.path.exists(filename + '.opt.bc'), 'Failed to run llvm optimizations: ' + output
    shutil.move(filename + '.opt.bc', filename)

  @staticmethod
  def llvm_opts(filename): # deprecated version, only for test runner. TODO: remove
    if Building.LLVM_OPTS:
      shutil.move(filename + '.o', filename + '.o.pre')
      output = Popen([LLVM_OPT, filename + '.o.pre'] + Building.LLVM_OPT_OPTS + ['-o=' + filename + '.o'], stdout=PIPE).communicate()[0]
      assert os.path.exists(filename + '.o'), 'Failed to run llvm optimizations: ' + output

  @staticmethod
  def llvm_dis(input_filename, output_filename=None):
    # LLVM binary ==> LLVM assembly
    if output_filename is None:
      # use test runner conventions
      output_filename = input_filename + '.o.ll'
      input_filename = input_filename + '.o'
    try_delete(output_filename)
    output = Popen([LLVM_DIS, input_filename, '-o=' + output_filename], stdout=PIPE).communicate()[0]
    assert os.path.exists(output_filename), 'Could not create .ll file: ' + output
    return output_filename

  @staticmethod
  def llvm_as(input_filename, output_filename=None):
    # LLVM assembly ==> LLVM binary
    if output_filename is None:
      # use test runner conventions
      output_filename = input_filename + '.o'
      input_filename = input_filename + '.o.ll'
    try_delete(output_filename)
    output = Popen([LLVM_AS, input_filename, '-o=' + output_filename], stdout=PIPE).communicate()[0]
    assert os.path.exists(output_filename), 'Could not create bc file: ' + output
    return output_filename

  nm_cache = {} # cache results of nm - it can be slow to run

  @staticmethod
  def llvm_nm(filename, stdout=PIPE, stderr=None):
    if filename in Building.nm_cache:
      #if DEBUG: print >> sys.stderr, 'loading nm results for %s from cache' % filename
      return Building.nm_cache[filename]

    # LLVM binary ==> list of symbols
    output = Popen([LLVM_NM, filename], stdout=stdout, stderr=stderr).communicate()[0]
    class ret:
      defs = []
      undefs = []
      commons = []
    for line in output.split('\n'):
      if len(line) == 0: continue
      parts = filter(lambda seg: len(seg) > 0, line.split(' '))
      if len(parts) == 2: # ignore lines with absolute offsets, these are not bitcode anyhow (e.g. |00000630 t d_source_name|)
        status, symbol = parts
        if status == 'U':
          ret.undefs.append(symbol)
        elif status != 'C':
          ret.defs.append(symbol)
        else:
          ret.commons.append(symbol)
    ret.defs = set(ret.defs)
    ret.undefs = set(ret.undefs)
    ret.commons = set(ret.commons)
    Building.nm_cache[filename] = ret
    return ret

  @staticmethod
  def emcc(filename, args=[], output_filename=None, stdout=None, stderr=None, env=None):
    if output_filename is None:
      output_filename = filename + '.o'
    try_delete(output_filename)
    Popen([PYTHON, EMCC, filename] + args + ['-o', output_filename], stdout=stdout, stderr=stderr, env=env).communicate()
    assert os.path.exists(output_filename), 'emcc could not create output file: ' + output_filename

  @staticmethod
  def emar(action, output_filename, filenames, stdout=None, stderr=None, env=None):
    try_delete(output_filename)
    Popen([PYTHON, EMAR, action, output_filename] + filenames, stdout=stdout, stderr=stderr, env=env).communicate()
    if 'c' in action:
      assert os.path.exists(output_filename), 'emar could not create output file: ' + output_filename

  @staticmethod
  def emscripten(filename, append_ext=True, extra_args=[]):
    # Allow usage of emscripten.py without warning
    os.environ['EMSCRIPTEN_SUPPRESS_USAGE_WARNING'] = '1'

    # Run Emscripten
    Settings.RELOOPER = Cache.get_path('relooper.js')
    settings = Settings.serialize()
    compiler_output = jsrun.timeout_run(Popen([PYTHON, EMSCRIPTEN, filename + ('.o.ll' if append_ext else ''), '-o', filename + '.o.js'] + settings + extra_args, stdout=PIPE), None, 'Compiling')
    #print compiler_output

    # Detect compilation crashes and errors
    if compiler_output is not None and 'Traceback' in compiler_output and 'in test_' in compiler_output: print compiler_output; assert 0
    assert os.path.exists(filename + '.o.js') and len(open(filename + '.o.js', 'r').read()) > 0, 'Emscripten failed to generate .js: ' + str(compiler_output)

    return filename + '.o.js'

  @staticmethod
  def can_build_standalone():
    return not Settings.BUILD_AS_SHARED_LIB and not Settings.LINKABLE

  @staticmethod
  def can_use_unsafe_opts():
    return Settings.USE_TYPED_ARRAYS == 2

  @staticmethod
  def can_inline():
    return Settings.INLINING_LIMIT == 0

  @staticmethod
  def get_safe_internalize():
    exports = ','.join(map(lambda exp: exp[1:], Settings.EXPORTED_FUNCTIONS))
    # internalize carefully, llvm 3.2 will remove even main if not told not to
    return ['-internalize', '-internalize-public-api-list=' + exports]

  @staticmethod
  def pick_llvm_opts(optimization_level):
    '''
      It may be safe to use nonportable optimizations (like -OX) if we remove the platform info from the .ll
      (which we do in do_ll_opts) - but even there we have issues (even in TA2) with instruction combining
      into i64s. In any case, the handpicked ones here should be safe and portable. They are also tuned for
      things that look useful.

      An easy way to see LLVM's standard list of passes is

        llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments
    '''
    assert 0 <= optimization_level <= 3
    unsafe = Building.can_use_unsafe_opts()
    opts = []
    if optimization_level > 0:
      if unsafe:
        if not Building.can_inline():
          opts.append('-disable-inlining')
        if not Building.can_build_standalone():
          # -O1 does not have -gobaldce, which removes stuff that is needed for libraries and linkables
          optimization_level = min(1, optimization_level)
        opts.append('-O%d' % optimization_level)
        #print '[unsafe: %s]' % ','.join(opts)
      else:
        allow_nonportable = False
        optimize_size = True
        use_aa = False

        # PassManagerBuilder::populateModulePassManager
        if allow_nonportable and use_aa: # ammo.js results indicate this can be nonportable
          opts.append('-tbaa')
          opts.append('-basicaa') # makes fannkuch slow but primes fast

        if Building.can_build_standalone():
          opts += Building.get_safe_internalize()

        opts.append('-globalopt')
        opts.append('-ipsccp')
        opts.append('-deadargelim')
        if allow_nonportable: opts.append('-instcombine')
        opts.append('-simplifycfg')

        opts.append('-prune-eh')
        if Building.can_inline(): opts.append('-inline')
        opts.append('-functionattrs')
        if optimization_level > 2:
          opts.append('-argpromotion')

        # XXX Danger: Can turn a memcpy into something that violates the
        #             load-store consistency hypothesis. See hashnum() in Lua.
        #             Note: this opt is of great importance for raytrace...
        if allow_nonportable: opts.append('-scalarrepl')

        if allow_nonportable: opts.append('-early-cse') # ?
        opts.append('-simplify-libcalls')
        opts.append('-jump-threading')
        if allow_nonportable: opts.append('-correlated-propagation') # ?
        opts.append('-simplifycfg')
        if allow_nonportable: opts.append('-instcombine')

        opts.append('-tailcallelim')
        opts.append('-simplifycfg')
        opts.append('-reassociate')
        opts.append('-loop-rotate')
        opts.append('-licm')
        opts.append('-loop-unswitch') # XXX should depend on optimize_size
        if allow_nonportable: opts.append('-instcombine')
        if Settings.QUANTUM_SIZE == 4: opts.append('-indvars') # XXX this infinite-loops raytrace on q1 (loop in |new node_t[count]| has 68 hardcoded &not fixed)
        if allow_nonportable: opts.append('-loop-idiom') # ?
        opts.append('-loop-deletion')
        opts.append('-loop-unroll')

        ##### not in llvm-3.0. but have |      #addExtensionsToPM(EP_LoopOptimizerEnd, MPM);| if allow_nonportable: opts.append('-instcombine')

        # XXX Danger: Messes up Lua output for unknown reasons
        #             Note: this opt is of minor importance for raytrace...
        if optimization_level > 1 and allow_nonportable: opts.append('-gvn')

        opts.append('-memcpyopt') # Danger?
        opts.append('-sccp')

        if allow_nonportable: opts.append('-instcombine')
        opts.append('-jump-threading')
        opts.append('-correlated-propagation')
        opts.append('-dse')
        #addExtensionsToPM(EP_ScalarOptimizerLate, MPM);

        opts.append('-adce')
        opts.append('-simplifycfg')
        if allow_nonportable: opts.append('-instcombine')

        opts.append('-strip-dead-prototypes')

        if Building.can_build_standalone():
          opts.append('-globaldce')

        if optimization_level > 1: opts.append('-constmerge')

    Building.LLVM_OPT_OPTS = opts
    return opts

  @staticmethod
  def js_optimizer(filename, passes, jcache):
    return js_optimizer.run(filename, passes, listify(NODE_JS), jcache)

  @staticmethod
  def closure_compiler(filename):
    if not os.path.exists(CLOSURE_COMPILER):
      raise Exception('Closure compiler appears to be missing, looked at: ' + str(CLOSURE_COMPILER))

    # Something like this (adjust memory as needed):
    #   java -Xmx1024m -jar CLOSURE_COMPILER --compilation_level ADVANCED_OPTIMIZATIONS --variable_map_output_file src.cpp.o.js.vars --js src.cpp.o.js --js_output_file src.cpp.o.cc.js
    args = [JAVA,
            '-Xmx' + (os.environ.get('JAVA_HEAP_SIZE') or '1024m'), # if you need a larger Java heap, use this environment variable
            '-jar', CLOSURE_COMPILER,
            '--compilation_level', 'ADVANCED_OPTIMIZATIONS',
            '--formatting', 'PRETTY_PRINT',
            '--language_in', 'ECMASCRIPT5',
            #'--variable_map_output_file', filename + '.vars',
            '--js', filename, '--js_output_file', filename + '.cc.js']
    if os.environ.get('EMCC_CLOSURE_ARGS'):
      args += shlex.split(os.environ.get('EMCC_CLOSURE_ARGS'))
    process = Popen(args, stdout=PIPE, stderr=STDOUT)
    cc_output = process.communicate()[0]
    if process.returncode != 0 or not os.path.exists(filename + '.cc.js'):
      raise Exception('closure compiler error: ' + cc_output + ' (rc: %d)' % process.returncode)

    return filename + '.cc.js'

  _is_ar_cache = {}
  @staticmethod
  def is_ar(filename):
    try:
      if Building._is_ar_cache.get(filename):
        return Building._is_ar_cache[filename]
      b = open(filename, 'r').read(8)
      sigcheck = b[0] == '!' and b[1] == '<' and \
                 b[2] == 'a' and b[3] == 'r' and \
                 b[4] == 'c' and b[5] == 'h' and \
                 b[6] == '>' and ord(b[7]) == 10
      Building._is_ar_cache[filename] = sigcheck
      return sigcheck
    except Exception, e:
      if DEBUG: print >> sys.stderr, 'shared.Building.is_ar failed to test whether file \'%s\' is a llvm archive file! Failed on exception: %s' % (filename, e)
      return False

  @staticmethod
  def is_bitcode(filename):
    # look for magic signature
    b = open(filename, 'r').read(4)
    if b[0] == 'B' and b[1] == 'C':
      return True
    # look for ar signature
    elif Building.is_ar(filename):
      return True
    # on OS X, there is a 20-byte prefix
    elif ord(b[0]) == 222 and ord(b[1]) == 192 and ord(b[2]) == 23 and ord(b[3]) == 11:
      b = open(filename, 'r').read(24)
      return b[20] == 'B' and b[21] == 'C'

    return False

  # Make sure the relooper exists. If it does not, check out the relooper code and bootstrap it
  @staticmethod
  def ensure_relooper(relooper):
    if os.path.exists(relooper): return
    Cache.ensure()
    curr = os.getcwd()
    try:
      ok = False
      print >> sys.stderr, '======================================='
      print >> sys.stderr, 'bootstrapping relooper...'
      os.chdir(path_from_root('src'))

      emcc_debug = os.environ.get('EMCC_DEBUG')
      if emcc_debug: del os.environ['EMCC_DEBUG']

      def make(opt_level):
        raw = relooper + '.raw.js'
        Building.emcc(os.path.join('relooper', 'Relooper.cpp'), ['-I' + os.path.join('relooper'), '--post-js',
          os.path.join('relooper', 'emscripten', 'glue.js'),
          '--memory-init-file', '0',
          '-s', 'TOTAL_MEMORY=67108864',
          '-s', 'EXPORTED_FUNCTIONS=["_rl_set_output_buffer","_rl_make_output_buffer","_rl_new_block","_rl_delete_block","_rl_block_add_branch_to","_rl_new_relooper","_rl_delete_relooper","_rl_relooper_add_block","_rl_relooper_calculate","_rl_relooper_render", "_rl_set_asm_js_mode"]',
          '-s', 'DEFAULT_LIBRARY_FUNCS_TO_INCLUDE=["memcpy", "memset", "malloc", "free", "puts"]',
          '-s', 'RELOOPER="' + relooper + '"',
          '-O' + str(opt_level), '--closure', '0'], raw)
        f = open(relooper, 'w')
        f.write("// Relooper, (C) 2012 Alon Zakai, MIT license, https://github.com/kripken/Relooper\n")
        f.write("var Relooper = (function() {\n");
        f.write(open(raw).read())
        f.write('\n  return Module.Relooper;\n')
        f.write('})();\n')
        f.close()

      # bootstrap phase 1: generate unrelooped relooper, for which we do not need a relooper (so we cannot recurse infinitely in this function)
      print >> sys.stderr, '  bootstrap phase 1'
      make(1)
      # bootstrap phase 2: generate relooped relooper, using the unrelooped relooper (we see relooper.js exists so we cannot recurse infinitely in this function)
      print >> sys.stderr, '  bootstrap phase 2'
      make(2)
      print >> sys.stderr, 'bootstrapping relooper succeeded'
      print >> sys.stderr, '======================================='
      ok = True
    finally:
      os.chdir(curr)
      if emcc_debug: os.environ['EMCC_DEBUG'] = emcc_debug
      if not ok:
        print >> sys.stderr, 'bootstrapping relooper failed. You may need to manually create relooper.js by compiling it, see src/relooper/emscripten'
        1/0

  @staticmethod
  def preprocess(infile, outfile):
    '''
      Preprocess source C/C++ in some special ways that emscripten needs. Returns
      a filename (potentially the same one if nothing was changed).

      Currently this only does emscripten_jcache_printf(..) rewriting.
    '''
    src = open(infile).read() # stack warning on jcacheprintf! in docs # add jcache printf test separatrely, for content of printf
    if 'emscripten_jcache_printf' not in src: return infile
    def fix(m):
      text = m.groups(0)[0]
      assert text.count('(') == 1 and text.count(')') == 1, 'must have simple expressions in emscripten_jcache_printf calls, no parens'
      assert text.count('"') == 2, 'must have simple expressions in emscripten_jcache_printf calls, no strings as varargs parameters'
      start = text.index('(')
      end = text.rindex(')')
      args = text[start+1:end].split(',')
      args = map(lambda x: x.strip(), args)
      if args[0][0] == '"':
        # flatten out
        args = map(lambda x: str(ord(x)), args[0][1:len(args[0])-1]) + ['0'] + args[1:]
      return 'emscripten_jcache_printf_(' + ','.join(args) + ')'
    src = re.sub(r'(emscripten_jcache_printf\([^)]+\))', lambda m: fix(m), src)
    open(outfile, 'w').write(src)
    return outfile

# compatibility with existing emcc, etc. scripts
Cache = cache.Cache(debug=DEBUG_CACHE)
JCache = cache.JCache(Cache)
chunkify = cache.chunkify

class JS:
  @staticmethod
  def to_nice_ident(ident): # limited version of the JS function toNiceIdent
    return ident.replace('%', '$').replace('@', '_');

# Compression of code and data for smaller downloads
class Compression:
  on = False

  @staticmethod
  def compressed_name(filename):
    return filename + '.compress'

  @staticmethod
  def compress(filename):
    execute(Compression.encoder, stdin=open(filename, 'rb'), stdout=open(Compression.compressed_name(filename), 'wb'))

  @staticmethod
  def worth_it(original, compressed):
    return compressed < original - 1500 # save at least one TCP packet or so

def execute(cmd, *args, **kw):
  try:
    return Popen(cmd, *args, **kw).communicate() # let compiler frontend print directly, so colors are saved (PIPE kills that)
  except:
    if not isinstance(cmd, str):
      cmd = ' '.join(cmd)
    print >> sys.stderr, 'Invoking Process failed: <<< ' + cmd + ' >>>'
    raise

def suffix(name):
  parts = name.split('.')
  if len(parts) > 1:
    return parts[-1]
  else:
    return None

def unsuffixed(name):
  return '.'.join(name.split('.')[:-1])

def unsuffixed_basename(name):
  return os.path.basename(unsuffixed(name))

import js_optimizer