1438   if (const Arg *A = Args.getLastArg(OPT_x)) {
1439     StringRef XValue = A->getValue();
1440
1441     // Parse suffixes: '<lang>(-header|[-module-map][-cpp-output])'.
1442     // FIXME: Supporting '<lang>-header-cpp-output' would be useful.
1443     bool Preprocessed = XValue.consume_back("-cpp-output");
1444     bool ModuleMap = XValue.consume_back("-module-map");
1445     IsHeaderFile =
1446         !Preprocessed && !ModuleMap && XValue.consume_back("-header");
1447
1448     // Principal languages.
1449     DashX = llvm::StringSwitch<InputKind>(XValue)
1450                 .Case("c", InputKind::C)
1451                 .Case("cl", InputKind::OpenCL)
1452                 .Case("cuda", InputKind::CUDA)
1453                 .Case("c++", InputKind::CXX)
1454                 .Case("objective-c", InputKind::ObjC)
1455                 .Case("objective-c++", InputKind::ObjCXX)
1456                 .Case("renderscript", InputKind::RenderScript)
1457                 .Default(InputKind::Unknown);
1458
1459     // "objc[++]-cpp-output" is an acceptable synonym for
1460     // "objective-c[++]-cpp-output".
1461     if (DashX.isUnknown() && Preprocessed && !IsHeaderFile && !ModuleMap)
1462       DashX = llvm::StringSwitch<InputKind>(XValue)
1463                   .Case("objc", InputKind::ObjC)
1464                   .Case("objc++", InputKind::ObjCXX)
1465                   .Default(InputKind::Unknown);
1466
1467     // Some special cases cannot be combined with suffixes.
1468     if (DashX.isUnknown() && !Preprocessed && !ModuleMap && !IsHeaderFile)
1469       DashX = llvm::StringSwitch<InputKind>(XValue)
1470                   .Case("cpp-output", InputKind(InputKind::C).getPreprocessed())
1471                   .Case("assembler-with-cpp", InputKind::Asm)
1472                   .Cases("ast", "pcm",
1473                          InputKind(InputKind::Unknown, InputKind::Precompiled))
1474                   .Case("ir", InputKind::LLVM_IR)
1475                   .Default(InputKind::Unknown);
1476
1477     if (DashX.isUnknown())
1478       Diags.Report(diag::err_drv_invalid_value)
1479         << A->getAsString(Args) << A->getValue();
1480
1481     if (Preprocessed)
1482       DashX = DashX.getPreprocessed();
1483     if (ModuleMap)
1484       DashX = DashX.withFormat(InputKind::ModuleMap);
1485   }