xref: /freebsd/contrib/llvm-project/clang/tools/driver/cc1as_main.cpp (revision f976241773df2260e6170317080761d1c5814fe5) 
1 //===-- cc1as_main.cpp - Clang Assembler  ---------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This is the entry point to the clang -cc1as functionality, which implements
10 // the direct interface to the LLVM MC based assembler.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Basic/Diagnostic.h"
15 #include "clang/Basic/DiagnosticOptions.h"
16 #include "clang/Driver/DriverDiagnostic.h"
17 #include "clang/Driver/Options.h"
18 #include "clang/Frontend/FrontendDiagnostic.h"
19 #include "clang/Frontend/TextDiagnosticPrinter.h"
20 #include "clang/Frontend/Utils.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/StringSwitch.h"
23 #include "llvm/ADT/Triple.h"
24 #include "llvm/IR/DataLayout.h"
25 #include "llvm/MC/MCAsmBackend.h"
26 #include "llvm/MC/MCAsmInfo.h"
27 #include "llvm/MC/MCCodeEmitter.h"
28 #include "llvm/MC/MCContext.h"
29 #include "llvm/MC/MCInstrInfo.h"
30 #include "llvm/MC/MCObjectFileInfo.h"
31 #include "llvm/MC/MCObjectWriter.h"
32 #include "llvm/MC/MCParser/MCAsmParser.h"
33 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
34 #include "llvm/MC/MCRegisterInfo.h"
35 #include "llvm/MC/MCSectionMachO.h"
36 #include "llvm/MC/MCStreamer.h"
37 #include "llvm/MC/MCSubtargetInfo.h"
38 #include "llvm/MC/MCTargetOptions.h"
39 #include "llvm/Option/Arg.h"
40 #include "llvm/Option/ArgList.h"
41 #include "llvm/Option/OptTable.h"
42 #include "llvm/Support/CommandLine.h"
43 #include "llvm/Support/ErrorHandling.h"
44 #include "llvm/Support/FileSystem.h"
45 #include "llvm/Support/FormattedStream.h"
46 #include "llvm/Support/Host.h"
47 #include "llvm/Support/MemoryBuffer.h"
48 #include "llvm/Support/Path.h"
49 #include "llvm/Support/Signals.h"
50 #include "llvm/Support/SourceMgr.h"
51 #include "llvm/Support/TargetRegistry.h"
52 #include "llvm/Support/TargetSelect.h"
53 #include "llvm/Support/Timer.h"
54 #include "llvm/Support/raw_ostream.h"
55 #include <memory>
56 #include <system_error>
57 using namespace clang;
58 using namespace clang::driver;
59 using namespace clang::driver::options;
60 using namespace llvm;
61 using namespace llvm::opt;
62 
63 namespace {
64 
65 /// Helper class for representing a single invocation of the assembler.
66 struct AssemblerInvocation {
67   /// @name Target Options
68   /// @{
69 
70   /// The name of the target triple to assemble for.
71   std::string Triple;
72 
73   /// If given, the name of the target CPU to determine which instructions
74   /// are legal.
75   std::string CPU;
76 
77   /// The list of target specific features to enable or disable -- this should
78   /// be a list of strings starting with '+' or '-'.
79   std::vector<std::string> Features;
80 
81   /// The list of symbol definitions.
82   std::vector<std::string> SymbolDefs;
83 
84   /// @}
85   /// @name Language Options
86   /// @{
87 
88   std::vector<std::string> IncludePaths;
89   unsigned NoInitialTextSection : 1;
90   unsigned SaveTemporaryLabels : 1;
91   unsigned GenDwarfForAssembly : 1;
92   unsigned RelaxELFRelocations : 1;
93   unsigned DwarfVersion;
94   std::string DwarfDebugFlags;
95   std::string DwarfDebugProducer;
96   std::string DebugCompilationDir;
97   std::map<const std::string, const std::string> DebugPrefixMap;
98   llvm::DebugCompressionType CompressDebugSections =
99       llvm::DebugCompressionType::None;
100   std::string MainFileName;
101   std::string SplitDwarfOutput;
102 
103   /// @}
104   /// @name Frontend Options
105   /// @{
106 
107   std::string InputFile;
108   std::vector<std::string> LLVMArgs;
109   std::string OutputPath;
110   enum FileType {
111     FT_Asm,  ///< Assembly (.s) output, transliterate mode.
112     FT_Null, ///< No output, for timing purposes.
113     FT_Obj   ///< Object file output.
114   };
115   FileType OutputType;
116   unsigned ShowHelp : 1;
117   unsigned ShowVersion : 1;
118 
119   /// @}
120   /// @name Transliterate Options
121   /// @{
122 
123   unsigned OutputAsmVariant;
124   unsigned ShowEncoding : 1;
125   unsigned ShowInst : 1;
126 
127   /// @}
128   /// @name Assembler Options
129   /// @{
130 
131   unsigned RelaxAll : 1;
132   unsigned NoExecStack : 1;
133   unsigned FatalWarnings : 1;
134   unsigned IncrementalLinkerCompatible : 1;
135   unsigned EmbedBitcode : 1;
136 
137   /// The name of the relocation model to use.
138   std::string RelocationModel;
139 
140   /// The ABI targeted by the backend. Specified using -target-abi. Empty
141   /// otherwise.
142   std::string TargetABI;
143 
144   /// @}
145 
146 public:
147   AssemblerInvocation() {
148     Triple = "";
149     NoInitialTextSection = 0;
150     InputFile = "-";
151     OutputPath = "-";
152     OutputType = FT_Asm;
153     OutputAsmVariant = 0;
154     ShowInst = 0;
155     ShowEncoding = 0;
156     RelaxAll = 0;
157     NoExecStack = 0;
158     FatalWarnings = 0;
159     IncrementalLinkerCompatible = 0;
160     DwarfVersion = 0;
161     EmbedBitcode = 0;
162   }
163 
164   static bool CreateFromArgs(AssemblerInvocation &Res,
165                              ArrayRef<const char *> Argv,
166                              DiagnosticsEngine &Diags);
167 };
168 
169 }
170 
171 bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
172                                          ArrayRef<const char *> Argv,
173                                          DiagnosticsEngine &Diags) {
174   bool Success = true;
175 
176   // Parse the arguments.
177   std::unique_ptr<OptTable> OptTbl(createDriverOptTable());
178 
179   const unsigned IncludedFlagsBitmask = options::CC1AsOption;
180   unsigned MissingArgIndex, MissingArgCount;
181   InputArgList Args = OptTbl->ParseArgs(Argv, MissingArgIndex, MissingArgCount,
182                                         IncludedFlagsBitmask);
183 
184   // Check for missing argument error.
185   if (MissingArgCount) {
186     Diags.Report(diag::err_drv_missing_argument)
187         << Args.getArgString(MissingArgIndex) << MissingArgCount;
188     Success = false;
189   }
190 
191   // Issue errors on unknown arguments.
192   for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
193     auto ArgString = A->getAsString(Args);
194     std::string Nearest;
195     if (OptTbl->findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
196       Diags.Report(diag::err_drv_unknown_argument) << ArgString;
197     else
198       Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
199           << ArgString << Nearest;
200     Success = false;
201   }
202 
203   // Construct the invocation.
204 
205   // Target Options
206   Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
207   Opts.CPU = Args.getLastArgValue(OPT_target_cpu);
208   Opts.Features = Args.getAllArgValues(OPT_target_feature);
209 
210   // Use the default target triple if unspecified.
211   if (Opts.Triple.empty())
212     Opts.Triple = llvm::sys::getDefaultTargetTriple();
213 
214   // Language Options
215   Opts.IncludePaths = Args.getAllArgValues(OPT_I);
216   Opts.NoInitialTextSection = Args.hasArg(OPT_n);
217   Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
218   // Any DebugInfoKind implies GenDwarfForAssembly.
219   Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
220 
221   if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections,
222                                      OPT_compress_debug_sections_EQ)) {
223     if (A->getOption().getID() == OPT_compress_debug_sections) {
224       // TODO: be more clever about the compression type auto-detection
225       Opts.CompressDebugSections = llvm::DebugCompressionType::GNU;
226     } else {
227       Opts.CompressDebugSections =
228           llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
229               .Case("none", llvm::DebugCompressionType::None)
230               .Case("zlib", llvm::DebugCompressionType::Z)
231               .Case("zlib-gnu", llvm::DebugCompressionType::GNU)
232               .Default(llvm::DebugCompressionType::None);
233     }
234   }
235 
236   Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
237   Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
238   Opts.DwarfDebugFlags = Args.getLastArgValue(OPT_dwarf_debug_flags);
239   Opts.DwarfDebugProducer = Args.getLastArgValue(OPT_dwarf_debug_producer);
240   Opts.DebugCompilationDir = Args.getLastArgValue(OPT_fdebug_compilation_dir);
241   Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
242 
243   for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ))
244     Opts.DebugPrefixMap.insert(StringRef(Arg).split('='));
245 
246   // Frontend Options
247   if (Args.hasArg(OPT_INPUT)) {
248     bool First = true;
249     for (const Arg *A : Args.filtered(OPT_INPUT)) {
250       if (First) {
251         Opts.InputFile = A->getValue();
252         First = false;
253       } else {
254         Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
255         Success = false;
256       }
257     }
258   }
259   Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
260   Opts.OutputPath = Args.getLastArgValue(OPT_o);
261   Opts.SplitDwarfOutput = Args.getLastArgValue(OPT_split_dwarf_output);
262   if (Arg *A = Args.getLastArg(OPT_filetype)) {
263     StringRef Name = A->getValue();
264     unsigned OutputType = StringSwitch<unsigned>(Name)
265       .Case("asm", FT_Asm)
266       .Case("null", FT_Null)
267       .Case("obj", FT_Obj)
268       .Default(~0U);
269     if (OutputType == ~0U) {
270       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
271       Success = false;
272     } else
273       Opts.OutputType = FileType(OutputType);
274   }
275   Opts.ShowHelp = Args.hasArg(OPT_help);
276   Opts.ShowVersion = Args.hasArg(OPT_version);
277 
278   // Transliterate Options
279   Opts.OutputAsmVariant =
280       getLastArgIntValue(Args, OPT_output_asm_variant, 0, Diags);
281   Opts.ShowEncoding = Args.hasArg(OPT_show_encoding);
282   Opts.ShowInst = Args.hasArg(OPT_show_inst);
283 
284   // Assemble Options
285   Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
286   Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
287   Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
288   Opts.RelocationModel = Args.getLastArgValue(OPT_mrelocation_model, "pic");
289   Opts.TargetABI = Args.getLastArgValue(OPT_target_abi);
290   Opts.IncrementalLinkerCompatible =
291       Args.hasArg(OPT_mincremental_linker_compatible);
292   Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
293 
294   // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
295   // EmbedBitcode behaves the same for all embed options for assembly files.
296   if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
297     Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
298                             .Case("all", 1)
299                             .Case("bitcode", 1)
300                             .Case("marker", 1)
301                             .Default(0);
302   }
303 
304   return Success;
305 }
306 
307 static std::unique_ptr<raw_fd_ostream>
308 getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
309   // Make sure that the Out file gets unlinked from the disk if we get a
310   // SIGINT.
311   if (Path != "-")
312     sys::RemoveFileOnSignal(Path);
313 
314   std::error_code EC;
315   auto Out = llvm::make_unique<raw_fd_ostream>(
316       Path, EC, (Binary ? sys::fs::F_None : sys::fs::F_Text));
317   if (EC) {
318     Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
319     return nullptr;
320   }
321 
322   return Out;
323 }
324 
325 static bool ExecuteAssembler(AssemblerInvocation &Opts,
326                              DiagnosticsEngine &Diags) {
327   // Get the target specific parser.
328   std::string Error;
329   const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
330   if (!TheTarget)
331     return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
332 
333   ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
334       MemoryBuffer::getFileOrSTDIN(Opts.InputFile);
335 
336   if (std::error_code EC = Buffer.getError()) {
337     Error = EC.message();
338     return Diags.Report(diag::err_fe_error_reading) << Opts.InputFile;
339   }
340 
341   SourceMgr SrcMgr;
342 
343   // Tell SrcMgr about this buffer, which is what the parser will pick up.
344   unsigned BufferIndex = SrcMgr.AddNewSourceBuffer(std::move(*Buffer), SMLoc());
345 
346   // Record the location of the include directories so that the lexer can find
347   // it later.
348   SrcMgr.setIncludeDirs(Opts.IncludePaths);
349 
350   std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
351   assert(MRI && "Unable to create target register info!");
352 
353   std::unique_ptr<MCAsmInfo> MAI(TheTarget->createMCAsmInfo(*MRI, Opts.Triple));
354   assert(MAI && "Unable to create target asm info!");
355 
356   // Ensure MCAsmInfo initialization occurs before any use, otherwise sections
357   // may be created with a combination of default and explicit settings.
358   MAI->setCompressDebugSections(Opts.CompressDebugSections);
359 
360   MAI->setRelaxELFRelocations(Opts.RelaxELFRelocations);
361 
362   bool IsBinary = Opts.OutputType == AssemblerInvocation::FT_Obj;
363   if (Opts.OutputPath.empty())
364     Opts.OutputPath = "-";
365   std::unique_ptr<raw_fd_ostream> FDOS =
366       getOutputStream(Opts.OutputPath, Diags, IsBinary);
367   if (!FDOS)
368     return true;
369   std::unique_ptr<raw_fd_ostream> DwoOS;
370   if (!Opts.SplitDwarfOutput.empty())
371     DwoOS = getOutputStream(Opts.SplitDwarfOutput, Diags, IsBinary);
372 
373   // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
374   // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
375   std::unique_ptr<MCObjectFileInfo> MOFI(new MCObjectFileInfo());
376 
377   MCContext Ctx(MAI.get(), MRI.get(), MOFI.get(), &SrcMgr);
378 
379   bool PIC = false;
380   if (Opts.RelocationModel == "static") {
381     PIC = false;
382   } else if (Opts.RelocationModel == "pic") {
383     PIC = true;
384   } else {
385     assert(Opts.RelocationModel == "dynamic-no-pic" &&
386            "Invalid PIC model!");
387     PIC = false;
388   }
389 
390   MOFI->InitMCObjectFileInfo(Triple(Opts.Triple), PIC, Ctx);
391   if (Opts.SaveTemporaryLabels)
392     Ctx.setAllowTemporaryLabels(false);
393   if (Opts.GenDwarfForAssembly)
394     Ctx.setGenDwarfForAssembly(true);
395   if (!Opts.DwarfDebugFlags.empty())
396     Ctx.setDwarfDebugFlags(StringRef(Opts.DwarfDebugFlags));
397   if (!Opts.DwarfDebugProducer.empty())
398     Ctx.setDwarfDebugProducer(StringRef(Opts.DwarfDebugProducer));
399   if (!Opts.DebugCompilationDir.empty())
400     Ctx.setCompilationDir(Opts.DebugCompilationDir);
401   else {
402     // If no compilation dir is set, try to use the current directory.
403     SmallString<128> CWD;
404     if (!sys::fs::current_path(CWD))
405       Ctx.setCompilationDir(CWD);
406   }
407   if (!Opts.DebugPrefixMap.empty())
408     for (const auto &KV : Opts.DebugPrefixMap)
409       Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
410   if (!Opts.MainFileName.empty())
411     Ctx.setMainFileName(StringRef(Opts.MainFileName));
412   Ctx.setDwarfVersion(Opts.DwarfVersion);
413   if (Opts.GenDwarfForAssembly)
414     Ctx.setGenDwarfRootFile(Opts.InputFile,
415                             SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());
416 
417   // Build up the feature string from the target feature list.
418   std::string FS;
419   if (!Opts.Features.empty()) {
420     FS = Opts.Features[0];
421     for (unsigned i = 1, e = Opts.Features.size(); i != e; ++i)
422       FS += "," + Opts.Features[i];
423   }
424 
425   std::unique_ptr<MCStreamer> Str;
426 
427   std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
428   std::unique_ptr<MCSubtargetInfo> STI(
429       TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
430 
431   raw_pwrite_stream *Out = FDOS.get();
432   std::unique_ptr<buffer_ostream> BOS;
433 
434   MCTargetOptions MCOptions;
435   MCOptions.ABIName = Opts.TargetABI;
436 
437   // FIXME: There is a bit of code duplication with addPassesToEmitFile.
438   if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
439     MCInstPrinter *IP = TheTarget->createMCInstPrinter(
440         llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
441 
442     std::unique_ptr<MCCodeEmitter> CE;
443     if (Opts.ShowEncoding)
444       CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
445     std::unique_ptr<MCAsmBackend> MAB(
446         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
447 
448     auto FOut = llvm::make_unique<formatted_raw_ostream>(*Out);
449     Str.reset(TheTarget->createAsmStreamer(
450         Ctx, std::move(FOut), /*asmverbose*/ true,
451         /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
452         Opts.ShowInst));
453   } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
454     Str.reset(createNullStreamer(Ctx));
455   } else {
456     assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
457            "Invalid file type!");
458     if (!FDOS->supportsSeeking()) {
459       BOS = make_unique<buffer_ostream>(*FDOS);
460       Out = BOS.get();
461     }
462 
463     std::unique_ptr<MCCodeEmitter> CE(
464         TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
465     std::unique_ptr<MCAsmBackend> MAB(
466         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
467     std::unique_ptr<MCObjectWriter> OW =
468         DwoOS ? MAB->createDwoObjectWriter(*Out, *DwoOS)
469               : MAB->createObjectWriter(*Out);
470 
471     Triple T(Opts.Triple);
472     Str.reset(TheTarget->createMCObjectStreamer(
473         T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI,
474         Opts.RelaxAll, Opts.IncrementalLinkerCompatible,
475         /*DWARFMustBeAtTheEnd*/ true));
476     Str.get()->InitSections(Opts.NoExecStack);
477   }
478 
479   // When -fembed-bitcode is passed to clang_as, a 1-byte marker
480   // is emitted in __LLVM,__asm section if the object file is MachO format.
481   if (Opts.EmbedBitcode && Ctx.getObjectFileInfo()->getObjectFileType() ==
482                                MCObjectFileInfo::IsMachO) {
483     MCSection *AsmLabel = Ctx.getMachOSection(
484         "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
485     Str.get()->SwitchSection(AsmLabel);
486     Str.get()->EmitZeros(1);
487   }
488 
489   // Assembly to object compilation should leverage assembly info.
490   Str->setUseAssemblerInfoForParsing(true);
491 
492   bool Failed = false;
493 
494   std::unique_ptr<MCAsmParser> Parser(
495       createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
496 
497   // FIXME: init MCTargetOptions from sanitizer flags here.
498   std::unique_ptr<MCTargetAsmParser> TAP(
499       TheTarget->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
500   if (!TAP)
501     Failed = Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
502 
503   // Set values for symbols, if any.
504   for (auto &S : Opts.SymbolDefs) {
505     auto Pair = StringRef(S).split('=');
506     auto Sym = Pair.first;
507     auto Val = Pair.second;
508     int64_t Value;
509     // We have already error checked this in the driver.
510     Val.getAsInteger(0, Value);
511     Ctx.setSymbolValue(Parser->getStreamer(), Sym, Value);
512   }
513 
514   if (!Failed) {
515     Parser->setTargetParser(*TAP.get());
516     Failed = Parser->Run(Opts.NoInitialTextSection);
517   }
518 
519   // Close Streamer first.
520   // It might have a reference to the output stream.
521   Str.reset();
522   // Close the output stream early.
523   BOS.reset();
524   FDOS.reset();
525 
526   // Delete output file if there were errors.
527   if (Failed) {
528     if (Opts.OutputPath != "-")
529       sys::fs::remove(Opts.OutputPath);
530     if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
531       sys::fs::remove(Opts.SplitDwarfOutput);
532   }
533 
534   return Failed;
535 }
536 
537 static void LLVMErrorHandler(void *UserData, const std::string &Message,
538                              bool GenCrashDiag) {
539   DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
540 
541   Diags.Report(diag::err_fe_error_backend) << Message;
542 
543   // We cannot recover from llvm errors.
544   exit(1);
545 }
546 
547 int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
548   // Initialize targets and assembly printers/parsers.
549   InitializeAllTargetInfos();
550   InitializeAllTargetMCs();
551   InitializeAllAsmParsers();
552 
553   // Construct our diagnostic client.
554   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
555   TextDiagnosticPrinter *DiagClient
556     = new TextDiagnosticPrinter(errs(), &*DiagOpts);
557   DiagClient->setPrefix("clang -cc1as");
558   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
559   DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
560 
561   // Set an error handler, so that any LLVM backend diagnostics go through our
562   // error handler.
563   ScopedFatalErrorHandler FatalErrorHandler
564     (LLVMErrorHandler, static_cast<void*>(&Diags));
565 
566   // Parse the arguments.
567   AssemblerInvocation Asm;
568   if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
569     return 1;
570 
571   if (Asm.ShowHelp) {
572     std::unique_ptr<OptTable> Opts(driver::createDriverOptTable());
573     Opts->PrintHelp(llvm::outs(), "clang -cc1as [options] file...",
574                     "Clang Integrated Assembler",
575                     /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
576                     /*ShowAllAliases=*/false);
577     return 0;
578   }
579 
580   // Honor -version.
581   //
582   // FIXME: Use a better -version message?
583   if (Asm.ShowVersion) {
584     llvm::cl::PrintVersionMessage();
585     return 0;
586   }
587 
588   // Honor -mllvm.
589   //
590   // FIXME: Remove this, one day.
591   if (!Asm.LLVMArgs.empty()) {
592     unsigned NumArgs = Asm.LLVMArgs.size();
593     auto Args = llvm::make_unique<const char*[]>(NumArgs + 2);
594     Args[0] = "clang (LLVM option parsing)";
595     for (unsigned i = 0; i != NumArgs; ++i)
596       Args[i + 1] = Asm.LLVMArgs[i].c_str();
597     Args[NumArgs + 1] = nullptr;
598     llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
599   }
600 
601   // Execute the invocation, unless there were parsing errors.
602   bool Failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
603 
604   // If any timers were active but haven't been destroyed yet, print their
605   // results now.
606   TimerGroup::printAll(errs());
607 
608   return !!Failed;
609 }
610