[Clang] Move assembler into a separate file

[aykevl]

Summary

This change adds an AssemblerInvocation class, similar to the CompilerInvocation class. It can be used to invoke cc1as directly.

The project I'm working on wants to compile Clang and use it as a static library. For that to work, there must be a way to invoke the assembler programmatically, using the same arguments as you would otherwise pass to cc1as.

---

This patch is outdated, updating it is fairly trivial. I'd like to have some feedback on the idea first, though.

[aykevl]

• removed useless anonymous namespace

[aykevl]

ping?

[aykevl]

*friendly ping*

[aykevl]

Ping?
This would be super useful to have: it avoids copying most of cc1as.

[aykevl]

Ping?
I'm not sure who to add as a reviewer.

[aykevl]

@echristo any chance you could take a look at this?

[echristo]

Hmm. In general I'd like to hear more about what you're trying. Can you give an idea of how you'd like to invoke the library to assemble something via clang? Why not just call into llvm directly? I'm not necessarily against changing the layering here fwiw, just wanted to get a better visual on what this is going to look like at the end and how it'll be used.

Thanks!

[aykevl]

(sorry, I missed your comment)

I basically want to run clang by linking to it and calling it directly, without invoking any external commands.
You can see here how I did it:
https://github.com/tinygo-org/tinygo/blob/master/builder/clang.cpp
I copied the cc1as code in the project and modified it a little bit to be callable, essentially what this patch does:
https://github.com/tinygo-org/tinygo/blob/master/builder/cc1as.cpp

Ideally there would be something like the tinygo_clang_driver in Clang. Maybe there is, the last time I looked I couldn't find it.
What is most important is that it will not try to call clang externally, because that will make distribution much harder.

As a sidenote: I have needed to work around some global state in Clang/LLVM by creating a new process (essentially calling argv[0]) and doing the C file compilation in there. As one compiler invocation of TinyGo may need to compile several C files, global state led to problems. This is different from calling clang as I'm still shipping a single statically linked binary instead of several binaries.

[aykevl]

The reason to not call into LLVM directly is because I want to use the compiler driver, to be compatible with all the compiler flags. Reimplementing the assembler driver would be a pain.

[aykevl]

ping?

[echristo]

Thanks for the explanation, lgtm.

-eric

[aykevl]

Thanks! I have updated this patch to match LLVM main and committed it.

[aykevl]

Well that didn't quite work. I get errors like this:

tools/clang/lib/Frontend/CMakeFiles/obj.clangFrontend.dir/AssemblerInvocation.cpp.o:(.toc+0x0): undefined reference to `vtable for llvm::MCSubtargetInfo'
tools/clang/lib/Frontend/CMakeFiles/obj.clangFrontend.dir/AssemblerInvocation.cpp.o: In function `clang::ExecuteAssembler(clang::AssemblerInvocation&, clang::DiagnosticsEngine&)':
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x418): undefined reference to `llvm::MCTargetOptions::MCTargetOptions()'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x564): undefined reference to `llvm::MCContext::MCContext(llvm::MCAsmInfo const*, llvm::MCRegisterInfo const*, llvm::MCObjectFileInfo const*, llvm::SourceMgr const*, llvm::MCTargetOptions const*, bool)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x5c0): undefined reference to `llvm::MCObjectFileInfo::InitMCObjectFileInfo(llvm::Triple const&, bool, llvm::MCContext&, bool)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x71c): undefined reference to `llvm::MCContext::addDebugPrefixMapEntry(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0xa1c): undefined reference to `llvm::MCAsmBackend::createDwoObjectWriter(llvm::raw_pwrite_stream&, llvm::raw_pwrite_stream&) const'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0xea0): undefined reference to `llvm::MCContext::setGenDwarfRootFile(llvm::StringRef, llvm::StringRef)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x11d8): undefined reference to `llvm::createAsmStreamer(llvm::MCContext&, std::unique_ptr<llvm::formatted_raw_ostream, std::default_delete<llvm::formatted_raw_ostream> >, bool, bool, llvm::MCInstPrinter*, std::unique_ptr<llvm::MCCodeEmitter, std::default_delete<llvm::MCCodeEmitter> >&&, std::unique_ptr<llvm::MCAsmBackend, std::default_delete<llvm::MCAsmBackend> >&&, bool)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x137c): undefined reference to `llvm::createMCAsmParser(llvm::SourceMgr&, llvm::MCContext&, llvm::MCStreamer&, llvm::MCAsmInfo const&, unsigned int)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x1460): undefined reference to `llvm::MCContext::setSymbolValue(llvm::MCStreamer&, llvm::StringRef, unsigned long)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x1500): undefined reference to `llvm::MCContext::setSymbolValue(llvm::MCStreamer&, llvm::StringRef, unsigned long)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x16dc): undefined reference to `llvm::MCContext::~MCContext()'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x1be8): undefined reference to `llvm::createELFStreamer(llvm::MCContext&, std::unique_ptr<llvm::MCAsmBackend, std::default_delete<llvm::MCAsmBackend> >&&, std::unique_ptr<llvm::MCObjectWriter, std::default_delete<llvm::MCObjectWriter> >&&, std::unique_ptr<llvm::MCCodeEmitter, std::default_delete<llvm::MCCodeEmitter> >&&, bool)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x1c08): undefined reference to `llvm::createXCOFFStreamer(llvm::MCContext&, std::unique_ptr<llvm::MCAsmBackend, std::default_delete<llvm::MCAsmBackend> >&&, std::unique_ptr<llvm::MCObjectWriter, std::default_delete<llvm::MCObjectWriter> >&&, std::unique_ptr<llvm::MCCodeEmitter, std::default_delete<llvm::MCCodeEmitter> >&&, bool)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x1d20): undefined reference to `llvm::MCContext::getMachOSection(llvm::StringRef, llvm::StringRef, unsigned int, unsigned int, llvm::SectionKind, char const*)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x1d54): undefined reference to `llvm::MCStreamer::emitZeros(unsigned long)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x1d68): undefined reference to `llvm::MCAsmParser::setTargetParser(llvm::MCTargetAsmParser&)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x2090): undefined reference to `llvm::MCAsmBackend::createObjectWriter(llvm::raw_pwrite_stream&) const'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x2128): undefined reference to `llvm::createNullStreamer(llvm::MCContext&)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x24e0): undefined reference to `llvm::createMachOStreamer(llvm::MCContext&, std::unique_ptr<llvm::MCAsmBackend, std::default_delete<llvm::MCAsmBackend> >&&, std::unique_ptr<llvm::MCObjectWriter, std::default_delete<llvm::MCObjectWriter> >&&, std::unique_ptr<llvm::MCCodeEmitter, std::default_delete<llvm::MCCodeEmitter> >&&, bool, bool, bool)'
AssemblerInvocation.cpp:(.text._ZN5clang16ExecuteAssemblerERNS_19AssemblerInvocationERNS_17DiagnosticsEngineE+0x2500): undefined reference to `llvm::createWasmStreamer(llvm::MCContext&, std::unique_ptr<llvm::MCAsmBackend, std::default_delete<llvm::MCAsmBackend> >&&, std::unique_ptr<llvm::MCObjectWriter, std::default_delete<llvm::MCObjectWriter> >&&, std::unique_ptr<llvm::MCCodeEmitter, std::default_delete<llvm::MCCodeEmitter> >&&, bool)'
collect2: error: ld returned 1 exit status

See:
http://lab.llvm.org:8011/#/builders/57/builds/3704
http://lab.llvm.org:8011/#/builders/112/builds/3216
http://lab.llvm.org:8011/#/builders/121/builds/3900

[aykevl]

@echristo do you have an idea what's going on or how to fix this? I suspect I'm not including a required dependency or maybe I've put AssemblerInvocation in the wrong directory/library.
I'm not very familiar with CMake or C++ so I'm not sure how to best fix this.

[hubert.reinterpretcast]

@aykevl, please check http://lab.llvm.org:8011/#/builders/57/builds/3704: it seems you are missing a change to clang/lib/Frontend/CMakeLists.txt to update the LLVM_LINK_COMPONENTS.

[hubert.reinterpretcast]

In D63852#2517500, @aykevl wrote:

or maybe I've put AssemblerInvocation in the wrong directory/library.

This seems to be a good design question. I think a lot of people consider -cc1 functionality to be the "frontend". I am not sure that goes for -cc1as functionality. This might even be a new library in a sense (a libclangAssemblyFrontend).

[aykevl]

Yeah I was wondering the same thing when I saw the failure. Unfortunately such design is a bit outside of my LLVM knowledge. I would just like to use cc1as_main.cpp functionality outside of LLVM without needing to update my copy of cc1as with every LLVM update.

clang/include/clang/Frontend/AssemblerInvocation.h

+//===- AssemblerInvocation.h - Assembler Invocation Helper Data -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_FRONTEND_ASSEMBLERINVOCATION_H
+#define LLVM_CLANG_FRONTEND_ASSEMBLERINVOCATION_H
+
+#include "llvm/MC/MCTargetOptions.h"
+
+namespace clang {
+
+/// Helper class for representing a single invocation of the assembler.
+struct AssemblerInvocation {
+  /// @name Target Options
+  /// @{
+
+  /// The name of the target triple to assemble for.
+  std::string Triple;
+
+  /// If given, the name of the target CPU to determine which instructions
+  /// are legal.
+  std::string CPU;
+
+  /// The list of target specific features to enable or disable -- this should
+  /// be a list of strings starting with '+' or '-'.
+  std::vector<std::string> Features;
+
+  /// The list of symbol definitions.
+  std::vector<std::string> SymbolDefs;
+
+  /// @}
+  /// @name Language Options
+  /// @{
+
+  std::vector<std::string> IncludePaths;
+  unsigned NoInitialTextSection : 1;
+  unsigned SaveTemporaryLabels : 1;
+  unsigned GenDwarfForAssembly : 1;
+  unsigned RelaxELFRelocations : 1;
+  unsigned DwarfVersion;
+  std::string DwarfDebugFlags;
+  std::string DwarfDebugProducer;
+  std::string DebugCompilationDir;
+  std::map<const std::string, const std::string> DebugPrefixMap;
+  llvm::DebugCompressionType CompressDebugSections =
+      llvm::DebugCompressionType::None;
+  std::string MainFileName;
+  std::string SplitDwarfOutput;
+
+  /// @}
+  /// @name Frontend Options
+  /// @{
+
+  std::string InputFile;
+  std::vector<std::string> LLVMArgs;
+  std::string OutputPath;
+  enum FileType {
+    FT_Asm,  ///< Assembly (.s) output, transliterate mode.
+    FT_Null, ///< No output, for timing purposes.
+    FT_Obj   ///< Object file output.
+  };
+  FileType OutputType;
+  unsigned ShowHelp : 1;
+  unsigned ShowVersion : 1;
+
+  /// @}
+  /// @name Transliterate Options
+  /// @{
+
+  unsigned OutputAsmVariant;
+  unsigned ShowEncoding : 1;
+  unsigned ShowInst : 1;
+
+  /// @}
+  /// @name Assembler Options
+  /// @{
+
+  unsigned RelaxAll : 1;
+  unsigned NoExecStack : 1;
+  unsigned FatalWarnings : 1;
+  unsigned NoWarn : 1;
+  unsigned IncrementalLinkerCompatible : 1;
+  unsigned EmbedBitcode : 1;
+
+  /// The name of the relocation model to use.
+  std::string RelocationModel;
+
+  /// The ABI targeted by the backend. Specified using -target-abi. Empty
+  /// otherwise.
+  std::string TargetABI;
+
+  /// @}
+
+public:
+  AssemblerInvocation() {
+    Triple = "";
+    NoInitialTextSection = 0;
+    InputFile = "-";
+    OutputPath = "-";
+    OutputType = FT_Asm;
+    OutputAsmVariant = 0;
+    ShowInst = 0;
+    ShowEncoding = 0;
+    RelaxAll = 0;
+    NoExecStack = 0;
+    FatalWarnings = 0;
+    NoWarn = 0;
+    IncrementalLinkerCompatible = 0;
+    DwarfVersion = 0;
+    EmbedBitcode = 0;
+  }
+
+  static bool CreateFromArgs(AssemblerInvocation &Res,
+                             ArrayRef<const char *> Argv,
+                             DiagnosticsEngine &Diags);
+};
+
+bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags);
+
+} // namespace clang
+
+#endif // LLVM_CLANG_FRONTEND_ASSEMBLERINVOCATION_H

clang/lib/Frontend/AssemblerInvocation.cpp

-//===-- cc1as_main.cpp - Clang Assembler  ---------------------------------===//
+//===- AssemblerInvocation.cpp ---------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
-// This is the entry point to the clang -cc1as functionality, which implements
-// the direct interface to the LLVM MC based assembler.
-//
-//===----------------------------------------------------------------------===//
 
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticOptions.h"
 #include "clang/Driver/DriverDiagnostic.h"
 #include "clang/Driver/Options.h"
+#include "clang/Frontend/AssemblerInvocation.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Frontend/Utils.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/MC/MCAsmBackend.h"

 #include "llvm/Option/OptTable.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
-#include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
 #include <memory>
 #include <system_error>
 using namespace clang;
 using namespace clang::driver;
 using namespace clang::driver::options;
 using namespace llvm;
 using namespace llvm::opt;
 
-namespace {
-
-/// Helper class for representing a single invocation of the assembler.
-struct AssemblerInvocation {
-  /// @name Target Options
-  /// @{
-
-  /// The name of the target triple to assemble for.
-  std::string Triple;
-
-  /// If given, the name of the target CPU to determine which instructions
-  /// are legal.
-  std::string CPU;
-
-  /// The list of target specific features to enable or disable -- this should
-  /// be a list of strings starting with '+' or '-'.
-  std::vector<std::string> Features;
-
-  /// The list of symbol definitions.
-  std::vector<std::string> SymbolDefs;
-
-  /// @}
-  /// @name Language Options
-  /// @{
-
-  std::vector<std::string> IncludePaths;
-  unsigned NoInitialTextSection : 1;
-  unsigned SaveTemporaryLabels : 1;
-  unsigned GenDwarfForAssembly : 1;
-  unsigned RelaxELFRelocations : 1;
-  unsigned DwarfVersion;
-  std::string DwarfDebugFlags;
-  std::string DwarfDebugProducer;
-  std::string DebugCompilationDir;
-  std::map<const std::string, const std::string> DebugPrefixMap;
-  llvm::DebugCompressionType CompressDebugSections =
-      llvm::DebugCompressionType::None;
-  std::string MainFileName;
-  std::string SplitDwarfOutput;
-
-  /// @}
-  /// @name Frontend Options
-  /// @{
-
-  std::string InputFile;
-  std::vector<std::string> LLVMArgs;
-  std::string OutputPath;
-  enum FileType {
-    FT_Asm,  ///< Assembly (.s) output, transliterate mode.
-    FT_Null, ///< No output, for timing purposes.
-    FT_Obj   ///< Object file output.
-  };
-  FileType OutputType;
-  unsigned ShowHelp : 1;
-  unsigned ShowVersion : 1;
-
-  /// @}
-  /// @name Transliterate Options
-  /// @{
-
-  unsigned OutputAsmVariant;
-  unsigned ShowEncoding : 1;
-  unsigned ShowInst : 1;
-
-  /// @}
-  /// @name Assembler Options
-  /// @{
-
-  unsigned RelaxAll : 1;
-  unsigned NoExecStack : 1;
-  unsigned FatalWarnings : 1;
-  unsigned NoWarn : 1;
-  unsigned IncrementalLinkerCompatible : 1;
-  unsigned EmbedBitcode : 1;
-
-  /// The name of the relocation model to use.
-  std::string RelocationModel;
-
-  /// The ABI targeted by the backend. Specified using -target-abi. Empty
-  /// otherwise.
-  std::string TargetABI;
-
-  /// @}
-
-public:
-  AssemblerInvocation() {
-    Triple = "";
-    NoInitialTextSection = 0;
-    InputFile = "-";
-    OutputPath = "-";
-    OutputType = FT_Asm;
-    OutputAsmVariant = 0;
-    ShowInst = 0;
-    ShowEncoding = 0;
-    RelaxAll = 0;
-    NoExecStack = 0;
-    FatalWarnings = 0;
-    NoWarn = 0;
-    IncrementalLinkerCompatible = 0;
-    DwarfVersion = 0;
-    EmbedBitcode = 0;
-  }
-
-  static bool CreateFromArgs(AssemblerInvocation &Res,
-                             ArrayRef<const char *> Argv,
-                             DiagnosticsEngine &Diags);
-};
-
-}
+namespace clang {
 
 bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
                                          ArrayRef<const char *> Argv,
                                          DiagnosticsEngine &Diags) {
   bool Success = true;
 
   // Parse the arguments.
   const OptTable &OptTbl = getDriverOptTable();
getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
   if (EC) {
     Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
     return nullptr;
   }
 
   return Out;
 }
 
-static bool ExecuteAssembler(AssemblerInvocation &Opts,
-                             DiagnosticsEngine &Diags) {
+bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
   // Get the target specific parser.
   std::string Error;
   const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
   if (!TheTarget)
     return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
 
   ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
       MemoryBuffer::getFileOrSTDIN(Opts.InputFile);
if (Opts.OutputPath != "-")
       sys::fs::remove(Opts.OutputPath);
     if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
       sys::fs::remove(Opts.SplitDwarfOutput);
   }
 
   return Failed;
 }
 
-static void LLVMErrorHandler(void *UserData, const std::string &Message,
-                             bool GenCrashDiag) {
-  DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
-
-  Diags.Report(diag::err_fe_error_backend) << Message;
-
-  // We cannot recover from llvm errors.
-  sys::Process::Exit(1);
-}
-
-int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
-  // Initialize targets and assembly printers/parsers.
-  InitializeAllTargetInfos();
-  InitializeAllTargetMCs();
-  InitializeAllAsmParsers();
-
-  // Construct our diagnostic client.
-  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
-  TextDiagnosticPrinter *DiagClient
-    = new TextDiagnosticPrinter(errs(), &*DiagOpts);
-  DiagClient->setPrefix("clang -cc1as");
-  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
-  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
-
-  // Set an error handler, so that any LLVM backend diagnostics go through our
-  // error handler.
-  ScopedFatalErrorHandler FatalErrorHandler
-    (LLVMErrorHandler, static_cast<void*>(&Diags));
-
-  // Parse the arguments.
-  AssemblerInvocation Asm;
-  if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
-    return 1;
-
-  if (Asm.ShowHelp) {
-    getDriverOptTable().PrintHelp(
-        llvm::outs(), "clang -cc1as [options] file...",
-        "Clang Integrated Assembler",
-        /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
-        /*ShowAllAliases=*/false);
-    return 0;
-  }
-
-  // Honor -version.
-  //
-  // FIXME: Use a better -version message?
-  if (Asm.ShowVersion) {
-    llvm::cl::PrintVersionMessage();
-    return 0;
-  }
-
-  // Honor -mllvm.
-  //
-  // FIXME: Remove this, one day.
-  if (!Asm.LLVMArgs.empty()) {
-    unsigned NumArgs = Asm.LLVMArgs.size();
-    auto Args = std::make_unique<const char*[]>(NumArgs + 2);
-    Args[0] = "clang (LLVM option parsing)";
-    for (unsigned i = 0; i != NumArgs; ++i)
-      Args[i + 1] = Asm.LLVMArgs[i].c_str();
-    Args[NumArgs + 1] = nullptr;
-    llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
-  }
-
-  // Execute the invocation, unless there were parsing errors.
-  bool Failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
-
-  // If any timers were active but haven't been destroyed yet, print their
-  // results now.
-  TimerGroup::printAll(errs());
-  TimerGroup::clearAll();
-
-  return !!Failed;
-}
+} // namespace clang

clang/lib/Frontend/CMakeLists.txt

 add_subdirectory(Rewrite)
 
 set(LLVM_LINK_COMPONENTS
   BitReader
   BitstreamReader
   Option
   ProfileData
   Support
   )
 
 add_clang_library(clangFrontend
+  AssemblerInvocation.cpp
   ASTConsumers.cpp
   ASTMerge.cpp
   ASTUnit.cpp
   ChainedDiagnosticConsumer.cpp
   ChainedIncludesSource.cpp
   CompilerInstance.cpp
   CompilerInvocation.cpp
   CreateInvocationFromCommandLine.cpp

clang/tools/driver/cc1as_main.cpp

 // the direct interface to the LLVM MC based assembler.
 //
 //===----------------------------------------------------------------------===//
 
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticOptions.h"
 #include "clang/Driver/DriverDiagnostic.h"
 #include "clang/Driver/Options.h"
+#include "clang/Frontend/AssemblerInvocation.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Frontend/Utils.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/MC/MCAsmBackend.h"

 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
 #include <memory>
 #include <system_error>
 using namespace clang;
-using namespace clang::driver;
-using namespace clang::driver::options;
 using namespace llvm;
 using namespace llvm::opt;
 
-namespace {
-
-/// Helper class for representing a single invocation of the assembler.
-struct AssemblerInvocation {
-  /// @name Target Options
-  /// @{
-
-  /// The name of the target triple to assemble for.
-  std::string Triple;
-
-  /// If given, the name of the target CPU to determine which instructions
-  /// are legal.
-  std::string CPU;
-
-  /// The list of target specific features to enable or disable -- this should
-  /// be a list of strings starting with '+' or '-'.
-  std::vector<std::string> Features;
-
-  /// The list of symbol definitions.
-  std::vector<std::string> SymbolDefs;
-
-  /// @}
-  /// @name Language Options
-  /// @{
-
-  std::vector<std::string> IncludePaths;
-  unsigned NoInitialTextSection : 1;
-  unsigned SaveTemporaryLabels : 1;
-  unsigned GenDwarfForAssembly : 1;
-  unsigned RelaxELFRelocations : 1;
-  unsigned DwarfVersion;
-  std::string DwarfDebugFlags;
-  std::string DwarfDebugProducer;
-  std::string DebugCompilationDir;
-  std::map<const std::string, const std::string> DebugPrefixMap;
-  llvm::DebugCompressionType CompressDebugSections =
-      llvm::DebugCompressionType::None;
-  std::string MainFileName;
-  std::string SplitDwarfOutput;
-
-  /// @}
-  /// @name Frontend Options
-  /// @{
-
-  std::string InputFile;
-  std::vector<std::string> LLVMArgs;
-  std::string OutputPath;
-  enum FileType {
-    FT_Asm,  ///< Assembly (.s) output, transliterate mode.
-    FT_Null, ///< No output, for timing purposes.
-    FT_Obj   ///< Object file output.
-  };
-  FileType OutputType;
-  unsigned ShowHelp : 1;
-  unsigned ShowVersion : 1;
-
-  /// @}
-  /// @name Transliterate Options
-  /// @{
-
-  unsigned OutputAsmVariant;
-  unsigned ShowEncoding : 1;
-  unsigned ShowInst : 1;
-
-  /// @}
-  /// @name Assembler Options
-  /// @{
-
-  unsigned RelaxAll : 1;
-  unsigned NoExecStack : 1;
-  unsigned FatalWarnings : 1;
-  unsigned NoWarn : 1;
-  unsigned IncrementalLinkerCompatible : 1;
-  unsigned EmbedBitcode : 1;
-
-  /// The name of the relocation model to use.
-  std::string RelocationModel;
-
-  /// The ABI targeted by the backend. Specified using -target-abi. Empty
-  /// otherwise.
-  std::string TargetABI;
-
-  /// @}
-
-public:
-  AssemblerInvocation() {
-    Triple = "";
-    NoInitialTextSection = 0;
-    InputFile = "-";
-    OutputPath = "-";
-    OutputType = FT_Asm;
-    OutputAsmVariant = 0;
-    ShowInst = 0;
-    ShowEncoding = 0;
-    RelaxAll = 0;
-    NoExecStack = 0;
-    FatalWarnings = 0;
-    NoWarn = 0;
-    IncrementalLinkerCompatible = 0;
-    DwarfVersion = 0;
-    EmbedBitcode = 0;
-  }
-
-  static bool CreateFromArgs(AssemblerInvocation &Res,
-                             ArrayRef<const char *> Argv,
-                             DiagnosticsEngine &Diags);
-};
-
-}
-
-bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
-                                         ArrayRef<const char *> Argv,
-                                         DiagnosticsEngine &Diags) {
-  bool Success = true;
-
-  // Parse the arguments.
-  const OptTable &OptTbl = getDriverOptTable();
-
-  const unsigned IncludedFlagsBitmask = options::CC1AsOption;
-  unsigned MissingArgIndex, MissingArgCount;
-  InputArgList Args = OptTbl.ParseArgs(Argv, MissingArgIndex, MissingArgCount,
-                                       IncludedFlagsBitmask);
-
-  // Check for missing argument error.
-  if (MissingArgCount) {
-    Diags.Report(diag::err_drv_missing_argument)
-        << Args.getArgString(MissingArgIndex) << MissingArgCount;
-    Success = false;
-  }
-
-  // Issue errors on unknown arguments.
-  for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
-    auto ArgString = A->getAsString(Args);
-    std::string Nearest;
-    if (OptTbl.findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
-      Diags.Report(diag::err_drv_unknown_argument) << ArgString;
-    else
-      Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
-          << ArgString << Nearest;
-    Success = false;
-  }
-
-  // Construct the invocation.
-
-  // Target Options
-  Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
-  Opts.CPU = std::string(Args.getLastArgValue(OPT_target_cpu));
-  Opts.Features = Args.getAllArgValues(OPT_target_feature);
-
-  // Use the default target triple if unspecified.
-  if (Opts.Triple.empty())
-    Opts.Triple = llvm::sys::getDefaultTargetTriple();
-
-  // Language Options
-  Opts.IncludePaths = Args.getAllArgValues(OPT_I);
-  Opts.NoInitialTextSection = Args.hasArg(OPT_n);
-  Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
-  // Any DebugInfoKind implies GenDwarfForAssembly.
-  Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
-
-  if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections_EQ)) {
-    Opts.CompressDebugSections =
-        llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
-            .Case("none", llvm::DebugCompressionType::None)
-            .Case("zlib", llvm::DebugCompressionType::Z)
-            .Case("zlib-gnu", llvm::DebugCompressionType::GNU)
-            .Default(llvm::DebugCompressionType::None);
-  }
-
-  Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
-  Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
-  Opts.DwarfDebugFlags =
-      std::string(Args.getLastArgValue(OPT_dwarf_debug_flags));
-  Opts.DwarfDebugProducer =
-      std::string(Args.getLastArgValue(OPT_dwarf_debug_producer));
-  Opts.DebugCompilationDir =
-      std::string(Args.getLastArgValue(OPT_fdebug_compilation_dir));
-  Opts.MainFileName = std::string(Args.getLastArgValue(OPT_main_file_name));
-
-  for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ)) {
-    auto Split = StringRef(Arg).split('=');
-    Opts.DebugPrefixMap.insert(
-        {std::string(Split.first), std::string(Split.second)});
-  }
-
-  // Frontend Options
-  if (Args.hasArg(OPT_INPUT)) {
-    bool First = true;
-    for (const Arg *A : Args.filtered(OPT_INPUT)) {
-      if (First) {
-        Opts.InputFile = A->getValue();
-        First = false;
-      } else {
-        Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
-        Success = false;
-      }
-    }
-  }
-  Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
-  Opts.OutputPath = std::string(Args.getLastArgValue(OPT_o));
-  Opts.SplitDwarfOutput =
-      std::string(Args.getLastArgValue(OPT_split_dwarf_output));
-  if (Arg *A = Args.getLastArg(OPT_filetype)) {
-    StringRef Name = A->getValue();
-    unsigned OutputType = StringSwitch<unsigned>(Name)
-      .Case("asm", FT_Asm)
-      .Case("null", FT_Null)
-      .Case("obj", FT_Obj)
-      .Default(~0U);
-    if (OutputType == ~0U) {
-      Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
-      Success = false;
-    } else
-      Opts.OutputType = FileType(OutputType);
-  }
-  Opts.ShowHelp = Args.hasArg(OPT_help);
-  Opts.ShowVersion = Args.hasArg(OPT_version);
-
-  // Transliterate Options
-  Opts.OutputAsmVariant =
-      getLastArgIntValue(Args, OPT_output_asm_variant, 0, Diags);
-  Opts.ShowEncoding = Args.hasArg(OPT_show_encoding);
-  Opts.ShowInst = Args.hasArg(OPT_show_inst);
-
-  // Assemble Options
-  Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
-  Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
-  Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
-  Opts.NoWarn = Args.hasArg(OPT_massembler_no_warn);
-  Opts.RelocationModel =
-      std::string(Args.getLastArgValue(OPT_mrelocation_model, "pic"));
-  Opts.TargetABI = std::string(Args.getLastArgValue(OPT_target_abi));
-  Opts.IncrementalLinkerCompatible =
-      Args.hasArg(OPT_mincremental_linker_compatible);
-  Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
-
-  // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
-  // EmbedBitcode behaves the same for all embed options for assembly files.
-  if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
-    Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
-                            .Case("all", 1)
-                            .Case("bitcode", 1)
-                            .Case("marker", 1)
-                            .Default(0);
-  }
-
-  return Success;
-}
-
-static std::unique_ptr<raw_fd_ostream>
-getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
-  // Make sure that the Out file gets unlinked from the disk if we get a
-  // SIGINT.
-  if (Path != "-")
-    sys::RemoveFileOnSignal(Path);
-
-  std::error_code EC;
-  auto Out = std::make_unique<raw_fd_ostream>(
-      Path, EC, (Binary ? sys::fs::OF_None : sys::fs::OF_Text));
-  if (EC) {
-    Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
-    return nullptr;
-  }
-
-  return Out;
-}
-
-static bool ExecuteAssembler(AssemblerInvocation &Opts,
-                             DiagnosticsEngine &Diags) {
-  // Get the target specific parser.
-  std::string Error;
-  const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
-  if (!TheTarget)
-    return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
-
-  ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
-      MemoryBuffer::getFileOrSTDIN(Opts.InputFile);
-
-  if (std::error_code EC = Buffer.getError()) {
-    Error = EC.message();
-    return Diags.Report(diag::err_fe_error_reading) << Opts.InputFile;
-  }
-
-  SourceMgr SrcMgr;
-
-  // Tell SrcMgr about this buffer, which is what the parser will pick up.
-  unsigned BufferIndex = SrcMgr.AddNewSourceBuffer(std::move(*Buffer), SMLoc());
-
-  // Record the location of the include directories so that the lexer can find
-  // it later.
-  SrcMgr.setIncludeDirs(Opts.IncludePaths);
-
-  std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
-  assert(MRI && "Unable to create target register info!");
-
-  MCTargetOptions MCOptions;
-  std::unique_ptr<MCAsmInfo> MAI(
-      TheTarget->createMCAsmInfo(*MRI, Opts.Triple, MCOptions));
-  assert(MAI && "Unable to create target asm info!");
-
-  // Ensure MCAsmInfo initialization occurs before any use, otherwise sections
-  // may be created with a combination of default and explicit settings.
-  MAI->setCompressDebugSections(Opts.CompressDebugSections);
-
-  MAI->setRelaxELFRelocations(Opts.RelaxELFRelocations);
-
-  bool IsBinary = Opts.OutputType == AssemblerInvocation::FT_Obj;
-  if (Opts.OutputPath.empty())
-    Opts.OutputPath = "-";
-  std::unique_ptr<raw_fd_ostream> FDOS =
-      getOutputStream(Opts.OutputPath, Diags, IsBinary);
-  if (!FDOS)
-    return true;
-  std::unique_ptr<raw_fd_ostream> DwoOS;
-  if (!Opts.SplitDwarfOutput.empty())
-    DwoOS = getOutputStream(Opts.SplitDwarfOutput, Diags, IsBinary);
-
-  // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
-  // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
-  std::unique_ptr<MCObjectFileInfo> MOFI(new MCObjectFileInfo());
-
-  MCContext Ctx(MAI.get(), MRI.get(), MOFI.get(), &SrcMgr, &MCOptions);
-
-  bool PIC = false;
-  if (Opts.RelocationModel == "static") {
-    PIC = false;
-  } else if (Opts.RelocationModel == "pic") {
-    PIC = true;
-  } else {
-    assert(Opts.RelocationModel == "dynamic-no-pic" &&
-           "Invalid PIC model!");
-    PIC = false;
-  }
-
-  MOFI->InitMCObjectFileInfo(Triple(Opts.Triple), PIC, Ctx);
-  if (Opts.SaveTemporaryLabels)
-    Ctx.setAllowTemporaryLabels(false);
-  if (Opts.GenDwarfForAssembly)
-    Ctx.setGenDwarfForAssembly(true);
-  if (!Opts.DwarfDebugFlags.empty())
-    Ctx.setDwarfDebugFlags(StringRef(Opts.DwarfDebugFlags));
-  if (!Opts.DwarfDebugProducer.empty())
-    Ctx.setDwarfDebugProducer(StringRef(Opts.DwarfDebugProducer));
-  if (!Opts.DebugCompilationDir.empty())
-    Ctx.setCompilationDir(Opts.DebugCompilationDir);
-  else {
-    // If no compilation dir is set, try to use the current directory.
-    SmallString<128> CWD;
-    if (!sys::fs::current_path(CWD))
-      Ctx.setCompilationDir(CWD);
-  }
-  if (!Opts.DebugPrefixMap.empty())
-    for (const auto &KV : Opts.DebugPrefixMap)
-      Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
-  if (!Opts.MainFileName.empty())
-    Ctx.setMainFileName(StringRef(Opts.MainFileName));
-  Ctx.setDwarfVersion(Opts.DwarfVersion);
-  if (Opts.GenDwarfForAssembly)
-    Ctx.setGenDwarfRootFile(Opts.InputFile,
-                            SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());
-
-  // Build up the feature string from the target feature list.
-  std::string FS = llvm::join(Opts.Features, ",");
-
-  std::unique_ptr<MCStreamer> Str;
-
-  std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
-  assert(MCII && "Unable to create instruction info!");
-
-  std::unique_ptr<MCSubtargetInfo> STI(
-      TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
-  assert(STI && "Unable to create subtarget info!");
-
-  raw_pwrite_stream *Out = FDOS.get();
-  std::unique_ptr<buffer_ostream> BOS;
-
-  MCOptions.MCNoWarn = Opts.NoWarn;
-  MCOptions.MCFatalWarnings = Opts.FatalWarnings;
-  MCOptions.ABIName = Opts.TargetABI;
-
-  // FIXME: There is a bit of code duplication with addPassesToEmitFile.
-  if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
-    MCInstPrinter *IP = TheTarget->createMCInstPrinter(
-        llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
-
-    std::unique_ptr<MCCodeEmitter> CE;
-    if (Opts.ShowEncoding)
-      CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
-    std::unique_ptr<MCAsmBackend> MAB(
-        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
-
-    auto FOut = std::make_unique<formatted_raw_ostream>(*Out);
-    Str.reset(TheTarget->createAsmStreamer(
-        Ctx, std::move(FOut), /*asmverbose*/ true,
-        /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
-        Opts.ShowInst));
-  } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
-    Str.reset(createNullStreamer(Ctx));
-  } else {
-    assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
-           "Invalid file type!");
-    if (!FDOS->supportsSeeking()) {
-      BOS = std::make_unique<buffer_ostream>(*FDOS);
-      Out = BOS.get();
-    }
-
-    std::unique_ptr<MCCodeEmitter> CE(
-        TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
-    std::unique_ptr<MCAsmBackend> MAB(
-        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
-    assert(MAB && "Unable to create asm backend!");
-
-    std::unique_ptr<MCObjectWriter> OW =
-        DwoOS ? MAB->createDwoObjectWriter(*Out, *DwoOS)
-              : MAB->createObjectWriter(*Out);
-
-    Triple T(Opts.Triple);
-    Str.reset(TheTarget->createMCObjectStreamer(
-        T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI,
-        Opts.RelaxAll, Opts.IncrementalLinkerCompatible,
-        /*DWARFMustBeAtTheEnd*/ true));
-    Str.get()->InitSections(Opts.NoExecStack);
-  }
-
-  // When -fembed-bitcode is passed to clang_as, a 1-byte marker
-  // is emitted in __LLVM,__asm section if the object file is MachO format.
-  if (Opts.EmbedBitcode && Ctx.getObjectFileInfo()->getObjectFileType() ==
-                               MCObjectFileInfo::IsMachO) {
-    MCSection *AsmLabel = Ctx.getMachOSection(
-        "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
-    Str.get()->SwitchSection(AsmLabel);
-    Str.get()->emitZeros(1);
-  }
-
-  // Assembly to object compilation should leverage assembly info.
-  Str->setUseAssemblerInfoForParsing(true);
-
-  bool Failed = false;
-
-  std::unique_ptr<MCAsmParser> Parser(
-      createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
-
-  // FIXME: init MCTargetOptions from sanitizer flags here.
-  std::unique_ptr<MCTargetAsmParser> TAP(
-      TheTarget->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
-  if (!TAP)
-    Failed = Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
-
-  // Set values for symbols, if any.
-  for (auto &S : Opts.SymbolDefs) {
-    auto Pair = StringRef(S).split('=');
-    auto Sym = Pair.first;
-    auto Val = Pair.second;
-    int64_t Value;
-    // We have already error checked this in the driver.
-    Val.getAsInteger(0, Value);
-    Ctx.setSymbolValue(Parser->getStreamer(), Sym, Value);
-  }
-
-  if (!Failed) {
-    Parser->setTargetParser(*TAP.get());
-    Failed = Parser->Run(Opts.NoInitialTextSection);
-  }
-
-  // Parser has a reference to the output stream (Str), so close Parser first.
-  Parser.reset();
-  Str.reset();
-  // Close the output stream early.
-  BOS.reset();
-  FDOS.reset();
-
-  // Delete output file if there were errors.
-  if (Failed) {
-    if (Opts.OutputPath != "-")
-      sys::fs::remove(Opts.OutputPath);
-    if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
-      sys::fs::remove(Opts.SplitDwarfOutput);
-  }
-
-  return Failed;
-}
-
 static void LLVMErrorHandler(void *UserData, const std::string &Message,
                              bool GenCrashDiag) {
   DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
 
   Diags.Report(diag::err_fe_error_backend) << Message;
 
   // We cannot recover from llvm errors.
   sys::Process::Exit(1);
ScopedFatalErrorHandler FatalErrorHandler
     (LLVMErrorHandler, static_cast<void*>(&Diags));
 
   // Parse the arguments.
   AssemblerInvocation Asm;
   if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
     return 1;
 
   if (Asm.ShowHelp) {
-    getDriverOptTable().PrintHelp(
+    clang::driver::getDriverOptTable().PrintHelp(
         llvm::outs(), "clang -cc1as [options] file...",
         "Clang Integrated Assembler",
         /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
         /*ShowAllAliases=*/false);
     return 0;
   }
 
   // Honor -version.