Function build_llvm

emsdk.py:1124–1181

(tool)

def build_llvm(tool):
  debug_print(f'build_llvm({tool})')
  llvm_root = tool.installation_path()
  llvm_src_root = os.path.join(llvm_root, 'src')
  success = git_clone_checkout_and_pull(tool.download_url(), llvm_src_root, tool.git_branch)
  if not success:
    return False

  build_dir = llvm_build_dir(tool)
  build_root = os.path.join(llvm_root, build_dir)

  build_type = decide_cmake_build_type(tool)

  # Configure
  tests_arg = 'ON' if BUILD_FOR_TESTING else 'OFF'

  enable_assertions = ENABLE_LLVM_ASSERTIONS.lower() == 'on' or (ENABLE_LLVM_ASSERTIONS == 'auto' and build_type.lower() != 'release' and build_type.lower() != 'minsizerel')

  if ARCH in {'x86', 'x86_64'}:
    targets_to_build = 'WebAssembly;X86'
  elif ARCH == 'arm':
    targets_to_build = 'WebAssembly;ARM'
  elif ARCH == 'arm64':
    targets_to_build = 'WebAssembly;AArch64'
  else:
    targets_to_build = 'WebAssembly'
  cmake_generator, args = get_generator_and_config_args(tool)
  args += ['-DLLVM_TARGETS_TO_BUILD=' + targets_to_build,
           '-DLLVM_INCLUDE_EXAMPLES=OFF',
           '-DLLVM_INCLUDE_TESTS=' + tests_arg,
           '-DCLANG_INCLUDE_TESTS=' + tests_arg,
           '-DLLVM_ENABLE_ASSERTIONS=' + ('ON' if enable_assertions else 'OFF'),
           # Disable optional LLVM dependencies, these can cause unwanted .so dependencies
           # that prevent distributing the generated compiler for end users.
           '-DLLVM_ENABLE_LIBXML2=OFF', '-DLLDB_ENABLE_LIBEDIT=OFF',
           '-DLLVM_ENABLE_LIBEDIT=OFF', '-DLLVM_ENABLE_LIBPFM=OFF']
  # LLVM build system bug: compiler-rt does not build on Windows. It insists on performing a CMake install step that writes to C:\Program Files. Attempting
  # to reroute that to build_root directory then fails on an error
  #  file INSTALL cannot find
  #  "C:/code/emsdk/llvm/git/build_master_vs2017_64/$(Configuration)/lib/clang/10.0.0/lib/windows/clang_rt.ubsan_standalone-x86_64.lib".
  # (there instead of $(Configuration), one would need ${CMAKE_BUILD_TYPE} ?)
  # It looks like compiler-rt is not compatible to build on Windows?
  args += ['-DLLVM_ENABLE_PROJECTS=clang;lld']
  # To enable widest possible chance of success for building, let the code
  # compile through with older toolchains that are about to be deprecated by
  # upstream LLVM.
  args += ['-DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN=ON']

  if os.getenv('LLVM_CMAKE_ARGS'):
    extra_args = os.environ['LLVM_CMAKE_ARGS'].split(',')
    print('Passing the following extra arguments to LLVM CMake configuration: ' + str(extra_args))
    args += extra_args

  cmakelists_dir = os.path.join(llvm_src_root, 'llvm')

  success = cmake_configure_and_build(cmake_generator, build_root, cmakelists_dir, build_type, args)

  return success