Function lld_flags_for_executable

tools/building.py:153–277

(external_symbols)

def lld_flags_for_executable(external_symbols):
  cmd = []
  if external_symbols:
    if settings.INCLUDE_FULL_LIBRARY:
      # When INCLUDE_FULL_LIBRARY is set try to export every possible
      # native dependency of a JS function.
      all_deps = set()
      for deps in external_symbols.values():
        for dep in deps:
          if dep not in all_deps:
            cmd.append('--export-if-defined=' + dep)
          all_deps.add(dep)
    stub = create_stub_object(external_symbols)
    cmd.append(stub)

  if settings.FAKE_DYLIBS or (not settings.MAIN_MODULE and not settings.SIDE_MODULE):
    cmd.append('-Bstatic')
  else:
    # wasm-ld still defaults to static linking by default. If that ever changes, we can remove this line.
    cmd.append('-Bdynamic')

  if not settings.ERROR_ON_UNDEFINED_SYMBOLS:
    cmd.append('--import-undefined')

  if settings.IMPORTED_MEMORY:
    cmd.append('--import-memory')

  if settings.SHARED_MEMORY:
    cmd.append('--shared-memory')

  # wasm-ld can strip debug info for us. this strips both the Names
  # section and DWARF, so we can only use it when we don't need any of
  # those things.
  if (not settings.GENERATE_DWARF and
      not settings.EMIT_SYMBOL_MAP and
      not settings.GENERATE_SOURCE_MAP and
      not settings.EMIT_NAME_SECTION and
      not settings.ASYNCIFY):
    cmd.append('--strip-debug')

  if settings.LTO and not settings.EXIT_RUNTIME:
    # The WebAssembly backend can generate new references to `__cxa_atexit` at
    # LTO time.  This `-u` flag forces the `__cxa_atexit` symbol to be
    # included at LTO time.  For other such symbols we exclude them from LTO
    # and always build them as normal object files, but that would inhibit the
    # LowerGlobalDtors optimization which allows destructors to be completely
    # removed when __cxa_atexit is a no-op.
    cmd.append('-u__cxa_atexit')

  c_exports = [e for e in settings.EXPORTED_FUNCTIONS if is_c_symbol(e)]
  # Strip the leading underscores
  c_exports = [demangle_c_symbol_name(e) for e in c_exports]
  # Filter out symbols external/JS symbols
  c_exports = [e for e in c_exports if e not in external_symbols]
  c_exports += settings.REQUIRED_EXPORTS
  if settings.MAIN_MODULE:
    c_exports += side_module_external_deps(external_symbols)
  for export in c_exports: