Move tools/llvm/driver to pnacl/driver.

tools/llvm/driver/pnacl-driver.py

-#!/usr/bin/python
-# Copyright (c) 2011 The Native Client Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-#
-# IMPORTANT NOTE: If you make local mods to this file, you must run:
-#   %  tools/llvm/utman.sh driver
-# in order for them to take effect in the scons build.  This command
-# updates the copy in the toolchain/ tree.
-#
-
-from driver_tools import *
-
-EXTRA_ENV = {
-  'ALLOW_TRANSLATE': '0',  # Allow bitcode translation before linking.
-                           # It doesn't normally make sense to do this.
-
-  'ALLOW_NATIVE'   : '0',  # Allow native objects (.S,.s,.o) to be in the
-                           # linker line for .pexe or .pso generation.
-                           # It doesn't normally make sense to do this.
-  'EMIT_LL'     : '1',    # Produce an intermediate .ll file
-                          # Currently enabled for debugging.
-  'BIAS'        : 'NONE', # This can be 'NONE', 'ARM', 'X8632', or 'X8664'.
-                          # When not set to none, this causes the front-end to
-                          # act like a target-specific compiler. This bias is
-                          # currently needed while compiling llvm-gcc, newlib,
-                          # and some scons tests.
-                          # TODO(pdox): Can this be removed?
-  'MC_DIRECT'   : '1',    # Use MC direct object emission instead of
-                          # producing an intermediate .s file
-  'LANGUAGE'    : 'C',    # C or CXX
-  'FRONTEND'    : '',     # CLANG, LLVMGCC, or DRAGONEGG
-
-  # Command-line options
-  'GCC_MODE'    : '',     # '' (default), '-E', '-c', or '-S'
-  'SHARED'      : '0',    # Produce a shared library
-  'STDINC'      : '1',    # Include standard headers (-nostdinc sets to 0)
-  'STDLIB'      : '1',    # Include standard libraries (-nostdlib sets to 0)
-  'DIAGNOSTIC'  : '0',    # Diagnostic flag detected
-  'STATIC'      : '${LIBMODE_NEWLIB ? 1 : 0}', # -static (on for newlib)
-  'PIC'         : '0',    # Generate PIC
-
-  'INPUTS'      : '',    # Input files
-  'OUTPUT'      : '',    # Output file
-  'UNMATCHED'   : '',    # Unrecognized parameters
-
-  # We need to remove the pre-existing ARM defines which appear
-  # because we are using the ARM llvm-gcc frontend.
-  # TODO(pdox): Prevent these from being defined by llvm-gcc in
-  #             the first place by creating a custom target for PNaCl.
-  'REMOVE_BIAS' : '-U__arm__ -U__APCS_32__ -U__thumb__ -U__thumb2__ ' +
-                  '-U__ARMEB__ -U__THUMBEB__ -U__ARMWEL__ ' +
-                  '-U__ARMEL__ -U__THUMBEL__ -U__SOFTFP__ ' +
-                  '-U__VFP_FP__ -U__ARM_NEON__ -U__ARM_FP16 ' +
-                  '-U__ARM_FP16__ -U__MAVERICK__ -U__XSCALE__ -U__IWMMXT__ ' +
-                  '-U__ARM_EABI__ -U__ARM_ARCH_7A__',
-
-  'BIAS_NONE'   : '${FRONTEND==LLVMGCC ? ${REMOVE_BIAS}}',
-  'BIAS_ARM'    : '-D__arm__ -D__ARM_ARCH_7A__ -D__ARMEL__',
-  'BIAS_X8632'  : '${REMOVE_BIAS} ' +
-                  '-D__i386__ -D__i386 -D__i686 -D__i686__ -D__pentium4__',
-  'BIAS_X8664'  : '${REMOVE_BIAS} ' +
-                  '-D__amd64__ -D__amd64 -D__x86_64__ -D__x86_64 -D__core2__',
-
-  'OPT_LEVEL'   : '0',
-  'CC_FLAGS'    : '-O${OPT_LEVEL} ' +
-                  '-nostdinc -DNACL_LINUX=1 ${BIAS_%BIAS%} ' +
-                  '${CC_FLAGS_%FRONTEND%}',
-  'CC_FLAGS_LLVMGCC': '-D__native_client__=1 -D__pnacl__=1 ' +
-                      '-fuse-llvm-va-arg -Werror-portable-llvm',
-  'CC_FLAGS_CLANG': '-ccc-host-triple le32-unknown-nacl',
-  'CC_FLAGS_DRAGONEGG': '-D__native_client__=1 -D__pnacl__=1 ' +
-                        '-flto -fplugin=${DRAGONEGG_PLUGIN}',
-
-  'ISYSTEM'        : '${ISYSTEM_USER} ${ISYSTEM_BUILTIN}',
-  'ISYSTEM_BUILTIN': '${STDINC ? ${ISYSTEM_%LIBMODE%}}',
-  'ISYSTEM_USER'   : '',  # System include directories specified by
-                          # using the -isystem flag.
-
-
-  'ISYSTEM_CLANG':
-      '${BASE_LLVM}/lib/clang/3.0/include ' +
-      # Fall back to gcc include, for unwind.h
-      '${BASE_LLVM_GCC}/lib/gcc/arm-none-linux-gnueabi/4.2.1/include',
-
-  'ISYSTEM_LLVMGCC':
-      '${BASE_LLVM_GCC}/lib/gcc/arm-none-linux-gnueabi/4.2.1/include ' +
-      '${BASE_LLVM_GCC}/' +
-        'lib/gcc/arm-none-linux-gnueabi/4.2.1/install-tools/include',
-
-  'ISYSTEM_DRAGONEGG':
-      '${BASE_LLVM_GCC}/lib/gcc/arm-none-linux-gnueabi/4.2.1/include ' +
-      '${BASE_LLVM_GCC}/' +
-        'lib/gcc/arm-none-linux-gnueabi/4.2.1/install-tools/include',
-
-  'ISYSTEM_newlib' :
-    '${BASE_SDK}/include ' +
-    '${ISYSTEM_%FRONTEND%} ' +
-    '${BASE_LIBSTDCPP}/include/c++/4.2.1 ' +
-    '${BASE_LIBSTDCPP}/include/c++/4.2.1/arm-none-linux-gnueabi ' +
-    '${BASE_INCLUDE} ' +
-    '${BASE_NEWLIB}/arm-none-linux-gnueabi/include',
-
-  'ISYSTEM_glibc' :
-    '${BASE_SDK}/include ' +
-    '${BASE_GLIBC}/include ' +
-    '${ISYSTEM_%FRONTEND%} ' +
-    '${BASE_GLIBC}/include/c++/4.4.3 ' +
-    '${BASE_GLIBC}/include/c++/4.4.3/x86_64-nacl',
-
-  'LD_FLAGS' : '-O${OPT_LEVEL} ${STATIC ? -static} ${SHARED ? -shared} ' +
-               '${PIC ? -fPIC} ${@AddPrefix:-L:SEARCH_DIRS}',
-
-  'SEARCH_DIRS'      : '${SEARCH_DIRS_USER} ${PREFIXES}',
-  'SEARCH_DIRS_USER' : '', # Directories specified using -L
-  'PREFIXES'         : '', # Prefixes specified by using the -B flag.
-
-  # Library Strings
-  'EMITMODE'         : '${STATIC ? static : ${SHARED ? shared : dynamic}}',
-
-  'LD_ARGS' : '${STDLIB ? ${LD_ARGS_%LIBMODE%_%EMITMODE%}' +
-                      ' : ${LD_ARGS_nostdlib}}',
-
-  # ${ld_inputs} signifies where to place the objects and libraries
-  # provided on the command-line.
-  'LD_ARGS_nostdlib': '-barebones-link -nostdlib ${ld_inputs}',
-
-  'LD_ARGS_newlib_static':
-    '-l:crt1.o -l:nacl_startup.bc ${ld_inputs} ' +
-    '--start-group -lgcc_eh -lgcc -lc -lnacl ' +
-    '${LIBSTDCPP} -l:libcrt_platform.a --end-group',
-
-  # The next three are copied verbatim from nacl-gcc
-  'LD_ARGS_glibc_static':
-    '-l:crt1.o -l:crti.o -l:crtbeginT.o ' +
-    '${ld_inputs} ${LIBSTDCPP} ' +
-    '--start-group -lgcc -lgcc_eh -lc ' +
-    '--end-group -l:crtend.o -l:crtn.o',
-
-  'LD_ARGS_glibc_shared':
-    '--eh-frame-hdr -shared -l:crti.o -l:crtbeginS.o ' +
-    '${ld_inputs} ${LIBSTDCPP} ' +
-    '-lgcc --as-needed -lgcc_s --no-as-needed ' +
-    '-lc -lgcc --as-needed -lgcc_s --no-as-needed ' +
-    '-l:crtendS.o -l:crtn.o',
-
-  'LD_ARGS_glibc_dynamic':
-    '--eh-frame-hdr -l:crt1.o -l:crti.o ' +
-    '-l:crtbegin.o ${ld_inputs} ${LIBSTDCPP} ' +
-    '-lgcc --as-needed -lgcc_s --no-as-needed ' +
-    '-lc -lgcc --as-needed -lgcc_s --no-as-needed ' +
-    '-l:crtend.o -l:crtn.o',
-
-  'LIBSTDCPP'   : '${LANGUAGE==CXX ? -lstdc++ -lm }',
-
-  'CC'              : '${CC_%FRONTEND%_%LANGUAGE%}',
-  'CC_LLVMGCC_C'    : '${LLVM_GCC}',
-  'CC_LLVMGCC_CXX'  : '${LLVM_GXX}',
-  'CC_CLANG_C'      : '${CLANG}',
-  'CC_CLANG_CXX'    : '${CLANGXX}',
-  'CC_DRAGONEGG_C'  : '${DRAGONEGG_GCC}',
-  'CC_DRAGONEGG_CXX': '${DRAGONEGG_GXX}',
-
-  'RUN_CC': '${CC} -emit-llvm ${mode} ${CC_FLAGS} ' +
-            '${@AddPrefix:-isystem :ISYSTEM} ' +
-            '${input} -o ${output}',
-
-  'RUN_PP' : '${CC} -E ${CC_FLAGS} ${@AddPrefix:-isystem :ISYSTEM} ' +
-             '"${input}" -o "${output}"'
-}
-env.update(EXTRA_ENV)
-
-def AddLDFlag(*args):
-  env.append('LD_FLAGS', *args)
-
-def AddCCFlag(*args):
-  env.append('CC_FLAGS', *args)
-
-def AddBPrefix(prefix):
-  prefix = pathtools.normalize(prefix)
-  if pathtools.isdir(prefix) and not prefix.endswith('/'):
-    prefix += '/'
-
-  env.append('PREFIXES', prefix)
-
-  # Add prefix/include to isystem if it exists
-  include_dir = prefix + 'include'
-  if pathtools.isdir(include_dir):
-    env.append('ISYSTEM_USER', include_dir)
-
-CustomPatterns = [
-  ( '--driver=(.+)',             "env.set('CC', pathtools.normalize($0))\n"),
-  ( '--pnacl-skip-ll',           "env.set('EMIT_LL', '0')"),
-
-  ( '--pnacl-gcc',               "env.set('LANGUAGE', 'C')\n"
-                                 "env.set('FRONTEND', 'LLVMGCC')"),
-  ( '--pnacl-gxx',               "env.set('LANGUAGE', 'CXX')\n"
-                                 "env.set('FRONTEND', 'LLVMGCC')"),
-
-  ( '--pnacl-clang',             "env.set('LANGUAGE', 'C')\n"
-                                 "env.set('FRONTEND', 'CLANG')"),
-  ( '--pnacl-clangxx',           "env.set('LANGUAGE', 'CXX')\n"
-                                 "env.set('FRONTEND', 'CLANG')"),
-
-  ( '--pnacl-dgcc',              "env.set('LANGUAGE', 'C')\n"
-                                 "env.set('FRONTEND', 'DRAGONEGG')"),
-  ( '--pnacl-dgxx',              "env.set('LANGUAGE', 'CXX')\n"
-                                 "env.set('FRONTEND', 'DRAGONEGG')"),
-
-  ( '--pnacl-allow-native',      "env.set('ALLOW_NATIVE', '1')"),
-  ( '--pnacl-allow-translate',   "env.set('ALLOW_TRANSLATE', '1')"),
-  ( '--pnacl-native-hack', "env.append('LD_FLAGS', '--pnacl-native-hack')\n"
-                           "env.set('ALLOW_NATIVE', '1')"),
-]
-
-GCCPatterns = [
-  ( '-o(.+)',          "env.set('OUTPUT', pathtools.normalize($0))"),
-  ( ('-o', '(.+)'),    "env.set('OUTPUT', pathtools.normalize($0))"),
-
-  ( '-E',              "env.set('GCC_MODE', '-E')"),
-  ( '-S',              "env.set('GCC_MODE', '-S')"),
-  ( '-c',              "env.set('GCC_MODE', '-c')"),
-
-  ( '-nostdinc',       "env.set('STDINC', '0')"),
-  ( '-nostdlib',       "env.set('STDLIB', '0')"),
-
-  # We don't care about -fPIC, but pnacl-ld and pnacl-translate do.
-  ( '-fPIC',           "env.set('PIC', '1')"),
-
-  # We must include -l, -Xlinker, and -Wl options into the INPUTS
-  # in the order they appeared. This is the exactly behavior of gcc.
-  # For example: gcc foo.c -Wl,--start-group -lx -ly -Wl,--end-group
-  #
-  ( '(-l.+)',             "env.append('INPUTS', $0)"),
-  ( ('(-l)','(.+)'),      "env.append('INPUTS', $0+$1)"),
-  ( ('-Xlinker','(.*)'),  "env.append('INPUTS', '-Xlinker=' + $0)"),
-  ( '(-Wl,.*)',           "env.append('INPUTS', $0)"),
-  ( '(-Bstatic)',         "env.append('INPUTS', $0)"),
-  ( '(-Bdynamic)',        "env.append('INPUTS', $0)"),
-
-  ( '-O([0-4s])',         "env.set('OPT_LEVEL', $0)\n"),
-  ( '-O',                 "env.set('OPT_LEVEL', '1')\n"),
-
-  ( ('-isystem', '(.*)'),
-                       "env.append('ISYSTEM_USER', pathtools.normalize($0))"),
-  ( ('-I', '(.+)'),    "env.append('CC_FLAGS', '-I'+pathtools.normalize($0))"),
-  ( '-I(.+)',          "env.append('CC_FLAGS', '-I'+pathtools.normalize($0))"),
-
-  ( '(-g)',                   AddCCFlag),
-  ( '(-W.*)',                 AddCCFlag),
-  ( '(-std=.*)',              AddCCFlag),
-  ( ('(-D)','(.*)'),          AddCCFlag),
-  ( '(-D.+)',                 AddCCFlag),
-  ( ('(-U)','(.*)'),          AddCCFlag),
-  ( '(-U.+)',                 AddCCFlag),
-  ( '(-f.*)',                 AddCCFlag),
-  ( '(-pedantic)',            AddCCFlag),
-  ( '(-pedantic-errors)',     AddCCFlag),
-  ( '(-g.*)',                 AddCCFlag),
-  ( '(-xassembler-with-cpp)', AddCCFlag),
-
-  ( '-shared',                "env.set('SHARED', '1')"),
-  ( '-static',                "env.set('STATIC', '1')"),
-
-  ( ('-B','(.*)'),            AddBPrefix),
-  ( ('-B(.+)'),               AddBPrefix),
-
-  ( ('-L','(.+)'), "env.append('SEARCH_DIRS_USER', pathtools.normalize($0))"),
-  ( '-L(.+)',      "env.append('SEARCH_DIRS_USER', pathtools.normalize($0))"),
-
-  ( '(-Wp,.*)',       AddCCFlag),
-  ( '(-MMD)',         AddCCFlag),
-  ( '(-MP)',          AddCCFlag),
-  ( '(-MD)',          AddCCFlag),
-  ( ('(-MT)','(.*)'), AddCCFlag),
-  ( ('(-MF)','(.*)'), "env.append('CC_FLAGS', $0, pathtools.normalize($1))"),
-
-  # With -xc, GCC considers future inputs to be an input source file.
-  # The following is not the correct handling of -x,
-  # but it works in the limited case used by llvm/configure.
-  # TODO(pdox): Make this -x really work in the general case.
-  ( '-xc',                    "env.append('CC_FLAGS', '-xc')\n"
-                              "SetForcedFileType('src')"),
-
-  # Ignore these gcc flags
-  ( '(-msse)',                ""),
-  ( '(-march=armv7-a)',       ""),
-
-  ( '(-s)',                   AddLDFlag),
-  ( '(--strip-all)',          AddLDFlag),
-  ( '(--strip-debug)',        AddLDFlag),
-
-  # Ignore these assembler flags
-  ( '(-Qy)',                  ""),
-  ( ('(--traditional-format)', '.*'), ""),
-  ( '(-gstabs)',              ""),
-  ( '(--gstabs)',             ""),
-  ( '(-gdwarf2)',             ""),
-  ( '(--gdwarf2)',             ""),
-  ( '(--fatal-warnings)',     ""),
-  ( '(-meabi=.*)',            ""),
-  ( '(-mfpu=.*)',             ""),
-
-  # GCC diagnostic mode triggers
-  ( '(-print-.*)',            "env.set('DIAGNOSTIC', '1')"),
-  ( '(--print.*)',            "env.set('DIAGNOSTIC', '1')"),
-  ( '(-dumpspecs)',           "env.set('DIAGNOSTIC', '1')"),
-  ( '(-v|--v|--version)',     "env.set('DIAGNOSTIC', '1')"),
-  ( '(-V)',                   "env.set('DIAGNOSTIC', '1')\n"
-                              "env.clear('CC_FLAGS')"),
-  ( '(-d.*)',                 "env.set('DIAGNOSTIC', '1')"),
-
-  # Catch all other command-line arguments
-  ( '(-.*)',              "env.append('UNMATCHED', $0)"),
-
-  # Input Files
-  # Call ForceFileType for all input files at the time they are
-  # parsed on the command-line. This ensures that the gcc "-x"
-  # setting is correctly applied.
-
-  ( '(.*)',  "env.append('INPUTS', pathtools.normalize($0))\n"
-             "ForceFileType(pathtools.normalize($0))"),
-]
-
-
-def main(argv):
-  _, real_argv = ParseArgs(argv, CustomPatterns, must_match = False)
-  ParseArgs(real_argv, GCCPatterns)
-
-  # "configure", especially when run as part of a toolchain bootstrap
-  # process, will invoke gcc with various diagnostic options and
-  # parse the output. In these cases we do not alter the incoming
-  # commandline. It is also important to not emit spurious messages.
-  if env.getbool('DIAGNOSTIC'):
-    RunWithLog(env.get('CC') + env.get('CC_FLAGS') + real_argv)
-    return 0
-
-  unmatched = env.get('UNMATCHED')
-  if len(unmatched) > 0:
-    UnrecognizedOption(*unmatched)
-
-  libmode_newlib = env.getbool('LIBMODE_NEWLIB')
-  is_static = env.getbool('STATIC')
-  is_shared = env.getbool('SHARED')
-
-  if libmode_newlib and (is_shared or not is_static):
-    Log.Fatal("Can't produce dynamic objects with newlib.")
-
-  if env.getbool('STATIC') and env.getbool('SHARED'):
-    Log.Fatal("Can't handle both -static and -shared")
-
-  inputs = env.get('INPUTS')
-  output = env.getone('OUTPUT')
-
-  if len(inputs) == 0:
-    Log.Fatal('No input files')
-
-  # If -arch was given, we are compiling directly to native code
-  compiling_to_native = GetArch() is not None
-
-  gcc_mode = env.getone('GCC_MODE')
-
-  if env.getbool('SHARED'):
-    bclink_output = 'pso'
-    link_output = 'so'
-  else:
-    bclink_output = 'pexe'
-    link_output = 'nexe'
-
-  output_type_map = {
-    ('-E', False) : 'pp',
-    ('-E', True)  : 'pp',
-    ('-c', False) : 'po',
-    ('-c', True)  : 'o',
-    ('-S', False) : 'll',
-    ('-S', True)  : 's',
-    ('',   False) : bclink_output,
-    ('',   True)  : link_output
-  }
-
-  output_type = output_type_map[(gcc_mode, compiling_to_native)]
-  needs_linking = (gcc_mode == '')
-
-  # There are multiple input files and no linking is being done.
-  # There will be multiple outputs. Handle this case separately.
-  if not needs_linking:
-    if output != '' and len(inputs) > 1:
-      Log.Fatal('Cannot have -o with -c, -S, or -E and multiple inputs')
-
-    for f in inputs:
-      if f.startswith('-'):
-        continue
-      intype = FileType(f)
-      if ((output_type == 'pp' and intype not in ('src','S')) or
-          (output_type == 'll' and intype not in 'src') or
-          (output_type == 'po' and intype not in ('src','ll')) or
-          (output_type == 's' and intype not in ('src','ll','po','S')) or
-          (output_type == 'o' and intype not in ('src','ll','po','S','s'))):
-        Log.Fatal("%s: Unexpected type of file for '%s'",
-                  pathtools.touser(f), gcc_mode)
-
-      if output == '':
-        f_output = DefaultOutputName(f, output_type)
-      else:
-        f_output = output
-
-      namegen = TempNameGen([f], f_output)
-      CompileOne(f, output_type, namegen, f_output)
-    return 0
-
-  # Linking case
-  assert(needs_linking)
-  assert(output_type in ('pso','so','pexe','nexe'))
-
-  if output == '':
-    output = pathtools.normalize('a.out')
-  namegen = TempNameGen(inputs, output)
-
-  # Compile all source files (c/c++/ll) to .po
-  for i in xrange(0, len(inputs)):
-    if inputs[i].startswith('-'):
-      continue
-    intype = FileType(inputs[i])
-    if intype in ('src','ll'):
-      inputs[i] = CompileOne(inputs[i], 'po', namegen)
-
-  # Compile all .s/.S to .o
-  if env.getbool('ALLOW_NATIVE'):
-    for i in xrange(0, len(inputs)):
-      if inputs[i].startswith('-'):
-        continue
-      intype = FileType(inputs[i])
-      if intype in ('s','S'):
-        inputs[i] = CompileOne(inputs[i], 'o', namegen)
-
-  # We should only be left with .po and .o and libraries
-  for f in inputs:
-    if f.startswith('-'):
-      continue
-    intype = FileType(f)
-    if intype in ('o','s','S') or IsNativeArchive(f):
-      if not env.getbool('ALLOW_NATIVE'):
-        Log.Fatal('%s: Native object files not allowed in link. '
-                  'Use --pnacl-allow-native to override.', pathtools.touser(f))
-    assert(intype in ('po','o','so','pso','ldscript') or IsArchive(f))
-
-  # Fix the user-specified linker arguments
-  ld_inputs = []
-  for f in inputs:
-    if f.startswith('-Xlinker='):
-      ld_inputs.append(f[len('-Xlinker='):])
-    elif f.startswith('-Wl,'):
-      ld_inputs += f[len('-Wl,'):].split(',')
-    else:
-      ld_inputs.append(f)
-
-  # Invoke the linker
-  env.set('ld_inputs', *ld_inputs)
-
-  ld_args = env.get('LD_ARGS')
-  ld_flags = env.get('LD_FLAGS')
-
-  RunDriver('pnacl-ld', ld_flags + ld_args + ['-o', output])
-  return 0
-
-def CompileOne(input, output_type, namegen, output = None):
-  if output is None:
-    output = namegen.TempNameForInput(input, output_type)
-
-  chain = DriverChain(input, output, namegen)
-  SetupChain(chain, FileType(input), output_type)
-  chain.run()
-  return output
-
-def RunPP(input, output):
-  RunWithEnv("${RUN_PP}", input=input, output=output)
-
-def RunCC(input, output, mode):
-  RunWithEnv("${RUN_CC}", input=input, output=output, mode=mode)
-
-def RunLLVMAS(input, output):
-  RunDriver('pnacl-as', [input, '-o', output], suppress_arch = True)
-
-def RunNativeAS(input, output):
-  RunDriver('pnacl-as', [input, '-o', output])
-
-def RunTranslate(input, output, mode):
-  if not env.getbool('ALLOW_TRANSLATE'):
-    Log.Fatal('%s: Trying to convert bitcode to an object file before '
-              'bitcode linking. This is supposed to wait until '
-              'translation. Use --pnacl-allow-translate to override.',
-              pathtools.touser(input))
-  args = [mode, input, '-o', output]
-  if env.getbool('PIC'):
-    args += ['-fPIC']
-  RunDriver('pnacl-translate', args)
-
-def SetupChain(chain, input_type, output_type):
-  assert(output_type in ('pp','ll','po','s','o'))
-  cur_type = input_type
-
-  # src -> pp
-  if cur_type == 'src' and output_type == 'pp':
-    chain.add(RunPP, 'cpp')
-    cur_type = 'pp'
-  if cur_type == output_type:
-    return
-
-  # src -> ll
-  if cur_type == 'src' and (env.getbool('EMIT_LL') or output_type == 'll'):
-    chain.add(RunCC, 'll', mode='-S')
-    cur_type = 'll'
-  if cur_type == output_type:
-    return
-
-  # ll -> po
-  if cur_type == 'll':
-    chain.add(RunLLVMAS, 'po')
-    cur_type = 'po'
-  if cur_type == output_type:
-    return
-
-  # src -> po
-  if cur_type == 'src' and output_type == 'po':
-    chain.add(RunCC, 'po', mode='-c')
-    cur_type = 'po'
-  if cur_type == output_type:
-    return
-
-  # po -> o
-  if env.getbool('MC_DIRECT') and cur_type == 'po' and output_type == 'o':
-    chain.add(RunTranslate, 'o', mode='-c')
-    cur_type = 'o'
-  if cur_type == output_type:
-    return
-
-  # po -> s
-  if cur_type == 'po':
-    chain.add(RunTranslate, 's', mode='-S')
-    cur_type = 's'
-  if cur_type == output_type:
-    return
-
-  # S -> s
-  if cur_type == 'S':
-    chain.add(RunPP, 's')
-    cur_type = 's'
-  if cur_type == output_type:
-    return
-
-  # s -> o
-  if cur_type == 's' and output_type == 'o':
-    chain.add(RunNativeAS, 'o')
-    cur_type = 'o'
-  if cur_type == output_type:
-    return
-
-  Log.Fatal("Unable to compile .%s to .%s", input_type, output_type)
-
-
-if __name__ == "__main__":
-  DriverMain(main)