Function emscript

tools/emscripten.py:356–476

(in_wasm, out_wasm, outfile_js, js_syms, finalize=True, base_metadata=None)

def emscript(in_wasm, out_wasm, outfile_js, js_syms, finalize=True, base_metadata=None):
  # Overview:
  #   * Run wasm-emscripten-finalize to extract metadata and modify the binary
  #     to use emscripten's wasm<->JS ABI
  #   * Use the metadata to generate the JS glue that goes with the wasm

  # set file locations, so that JS glue can find what it needs
  settings.WASM_BINARY_FILE = js_manipulation.escape_for_js_string(os.path.basename(out_wasm))

  if finalize:
    metadata = finalize_wasm(in_wasm, out_wasm, js_syms)
  else:
    # Skip finalize and only extract the metadata.
    if in_wasm != out_wasm:
      shutil.copy(in_wasm, out_wasm)
    metadata = get_metadata(in_wasm, out_wasm, False, [])

  # If the binary has already been finalized the settings have already been
  # updated and we can skip updating them.
  if finalize:
    update_settings_glue(out_wasm, metadata, base_metadata)

  if not settings.WASM_BIGINT and metadata.em_js_funcs:
    for em_js_func, raw in metadata.em_js_funcs.items():
      args, _ = raw.split('<::>', 1)
      args = args[1:-1].strip()

      if not args or args == 'void':
        args = []
      else:
        args = args.split(',')
      signature = metadata.em_js_func_types.get(em_js_func)
      if signature and len(signature.params) != len(args):
        diagnostics.warning('em-js-i64', 'using 64-bit arguments in EM_JS function without WASM_BIGINT is not yet fully supported: `%s` (%s, %s)', em_js_func, args, signature.params)

  asm_consts = create_asm_consts(metadata)
  em_js_funcs = create_em_js(metadata)

  if settings.SIDE_MODULE:
    # When building side modules, validate the EM_ASM and EM_JS string by running
    # them through node.  Without this step, syntax errors are not surfaced
    # until runtime.
    # We use subprocess directly here rather than shared.check_call since
    # check_call doesn't support the `input` argument.
    if asm_consts:
      validate = '\n'.join([f'var tmp = {f};' for _, f in asm_consts])
      proc = subprocess.run([*config.NODE_JS, '--check', '-'], input=validate.encode('utf-8'))
      if proc.returncode:
        exit_with_error(f'EM_ASM function validation failed (node returned {proc.returncode})')

    if em_js_funcs:
      validate = '\n'.join(em_js_funcs)
      proc = subprocess.run([*config.NODE_JS, '--check', '-'], input=validate.encode('utf-8'))
      if proc.returncode:
        exit_with_error(f'EM_JS function validation failed (node returned {proc.returncode})')

  if not outfile_js:
    report_missing_exports_wasm_only(metadata)