emcc_wrapper.py

# This is a simple wrapper for the "emcc" command from the emscripten compiler.
# Unlike the emscripten SDK script, it lets you specify the compiler version
# number. Just pass the version number using the "--version" flag and put the
# flags for "emcc" after the "--":
#
#   python emcc_wrapper.py --version 1.27.0 -- -O3 -s NO_EXIT_RUNTIME=1 ...
#
import os
import sys
import pipes
import urllib2
import hashlib
import subprocess
import argparse

cache_folder = os.path.expanduser('~/.emcc_wrapper')

def run(command, **kwargs):
  print ' '.join(map(pipes.quote, command))
  subprocess.check_call(command, **kwargs)

def mkdir(path):
  try:
    os.makedirs(path)
  except:
    pass

def fetch(url):
  print 'fetching', url
  request = urllib2.urlopen(url)
  content = ''
  while True:
    chunk = request.read(128 * 1024)
    if not chunk:
      sys.stdout.write('\n')
      return content
    content += chunk
    sys.stdout.write('\r%.1f mb' % (float(len(content)) / (1024 * 1024)))
    sys.stdout.flush()

def extract(file, folder):
  print 'extracting to', folder
  mkdir(folder)
  run(['unzip', file, '-d', folder])

def download(url):
  path = os.path.join(cache_folder, 'downloads', hashlib.md5(url).hexdigest())
  if not os.path.exists(path):
    content = fetch(url)
    mkdir(os.path.dirname(path))
    open(path, 'w').write(content)
  return path

def download_github_release(repo, version, path):
  url = 'https://github.com/kripken/%s/archive/%s.zip' % (repo, version)
  path = os.path.join(cache_folder, version, path)
  if not os.path.exists(path):
    temp = path + '-temp'
    extract(download(url), temp)
    nested = os.path.join(temp, '%s-%s' % (repo, version))
    if os.path.exists(nested):
      os.rename(nested, path)
      os.rmdir(temp)
    else:
      os.rename(temp, path)
  return path

def build_llvm(source, version):
  target = os.path.join(os.path.dirname(source), 'llvm-build')
  if not os.path.exists(target):
    mkdir(target)
    flags = [
      # These are from http://kripken.github.io/emscripten-site/docs/building_from_source/building_fastcomp_manually_from_source.html
      '-DCMAKE_BUILD_TYPE=Release',
      '-DLLVM_TARGETS_TO_BUILD=X86;JSBackend',
      '-DLLVM_INCLUDE_EXAMPLES=OFF',
      '-DLLVM_INCLUDE_TESTS=OFF',
      '-DCLANG_INCLUDE_EXAMPLES=OFF',
      '-DCLANG_INCLUDE_TESTS=OFF',
    ]
    run(['cmake', source] + flags, cwd=target)
    run(['make', '-j4'], cwd=target)
  return os.path.join(target, 'bin')

def main():
  parser = argparse.ArgumentParser()
  parser.add_argument('arguments', metavar='ARGUMENT', nargs='*', help='arguments for the real emcc')
  parser.add_argument('--version', required=True, help='the emscripten SDK version')
  parser.add_argument('--python', default='python', help='the python binary to use')
  options = parser.parse_args()

  emscripten_path = download_github_release('emscripten', options.version, 'emscripten')
  llvm_path = download_github_release('emscripten-fastcomp', options.version, 'emscripten-fastcomp')
  clang_path = download_github_release('emscripten-fastcomp-clang', options.version, os.path.join('emscripten-fastcomp', 'tools', 'clang'))
  bin_path = build_llvm(llvm_path, options.version)

  config = [
    ('EMSCRIPTEN_ROOT', emscripten_path),
    ('LLVM_ROOT', bin_path),
    ('NODE_JS', 'node'),
    ('COMPILER_ENGINE', 'node'),
    ('JS_ENGINES', ['node']),
  ]

  command = [options.python, os.path.join(emscripten_path, 'emcc')]
  command += ['--em-config', ';'.join('%s=%s' % (name, repr(value)) for name, value in config)]
  command += options.arguments
  run(command)

if __name__ == '__main__':
  main()