xref: /freebsd/contrib/llvm-project/clang/tools/driver/cc1as_main.cpp (revision b4af4f93c682e445bf159f0d1ec90b636296c946) 
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/Process.h"
50 #include "llvm/Support/Signals.h"
51 #include "llvm/Support/SourceMgr.h"
52 #include "llvm/Support/TargetRegistry.h"
53 #include "llvm/Support/TargetSelect.h"
54 #include "llvm/Support/Timer.h"
55 #include "llvm/Support/raw_ostream.h"
56 #include <memory>
57 #include <system_error>
58 using namespace clang;
59 using namespace clang::driver;
60 using namespace clang::driver::options;
61 using namespace llvm;
62 using namespace llvm::opt;
63 
64 namespace {
65 
66 /// Helper class for representing a single invocation of the assembler.
67 struct AssemblerInvocation {
68   /// @name Target Options
69   /// @{
70 
71   /// The name of the target triple to assemble for.
72   std::string Triple;
73 
74   /// If given, the name of the target CPU to determine which instructions
75   /// are legal.
76   std::string CPU;
77 
78   /// The list of target specific features to enable or disable -- this should
79   /// be a list of strings starting with '+' or '-'.
80   std::vector<std::string> Features;
81 
82   /// The list of symbol definitions.
83   std::vector<std::string> SymbolDefs;
84 
85   /// @}
86   /// @name Language Options
87   /// @{
88 
89   std::vector<std::string> IncludePaths;
90   unsigned NoInitialTextSection : 1;
91   unsigned SaveTemporaryLabels : 1;
92   unsigned GenDwarfForAssembly : 1;
93   unsigned RelaxELFRelocations : 1;
94   unsigned DwarfVersion;
95   std::string DwarfDebugFlags;
96   std::string DwarfDebugProducer;
97   std::string DebugCompilationDir;
98   std::map<const std::string, const std::string> DebugPrefixMap;
99   llvm::DebugCompressionType CompressDebugSections =
100       llvm::DebugCompressionType::None;
101   std::string MainFileName;
102   std::string SplitDwarfOutput;
103 
104   /// @}
105   /// @name Frontend Options
106   /// @{
107 
108   std::string InputFile;
109   std::vector<std::string> LLVMArgs;
110   std::string OutputPath;
111   enum FileType {
112     FT_Asm,  ///< Assembly (.s) output, transliterate mode.
113     FT_Null, ///< No output, for timing purposes.
114     FT_Obj   ///< Object file output.
115   };
116   FileType OutputType;
117   unsigned ShowHelp : 1;
118   unsigned ShowVersion : 1;
119 
120   /// @}
121   /// @name Transliterate Options
122   /// @{
123 
124   unsigned OutputAsmVariant;
125   unsigned ShowEncoding : 1;
126   unsigned ShowInst : 1;
127 
128   /// @}
129   /// @name Assembler Options
130   /// @{
131 
132   unsigned RelaxAll : 1;
133   unsigned NoExecStack : 1;
134   unsigned FatalWarnings : 1;
135   unsigned NoWarn : 1;
136   unsigned IncrementalLinkerCompatible : 1;
137   unsigned EmbedBitcode : 1;
138 
139   /// The name of the relocation model to use.
140   std::string RelocationModel;
141 
142   /// The ABI targeted by the backend. Specified using -target-abi. Empty
143   /// otherwise.
144   std::string TargetABI;
145 
146   /// @}
147 
148 public:
149   AssemblerInvocation() {
150     Triple = "";
151     NoInitialTextSection = 0;
152     InputFile = "-";
153     OutputPath = "-";
154     OutputType = FT_Asm;
155     OutputAsmVariant = 0;
156     ShowInst = 0;
157     ShowEncoding = 0;
158     RelaxAll = 0;
159     NoExecStack = 0;
160     FatalWarnings = 0;
161     NoWarn = 0;
162     IncrementalLinkerCompatible = 0;
163     DwarfVersion = 0;
164     EmbedBitcode = 0;
165   }
166 
167   static bool CreateFromArgs(AssemblerInvocation &Res,
168                              ArrayRef<const char *> Argv,
169                              DiagnosticsEngine &Diags);
170 };
171 
172 }
173 
174 bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
175                                          ArrayRef<const char *> Argv,
176                                          DiagnosticsEngine &Diags) {
177   bool Success = true;
178 
179   // Parse the arguments.
180   const OptTable &OptTbl = getDriverOptTable();
181 
182   const unsigned IncludedFlagsBitmask = options::CC1AsOption;
183   unsigned MissingArgIndex, MissingArgCount;
184   InputArgList Args = OptTbl.ParseArgs(Argv, MissingArgIndex, MissingArgCount,
185                                        IncludedFlagsBitmask);
186 
187   // Check for missing argument error.
188   if (MissingArgCount) {
189     Diags.Report(diag::err_drv_missing_argument)
190         << Args.getArgString(MissingArgIndex) << MissingArgCount;
191     Success = false;
192   }
193 
194   // Issue errors on unknown arguments.
195   for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
196     auto ArgString = A->getAsString(Args);
197     std::string Nearest;
198     if (OptTbl.findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
199       Diags.Report(diag::err_drv_unknown_argument) << ArgString;
200     else
201       Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
202           << ArgString << Nearest;
203     Success = false;
204   }
205 
206   // Construct the invocation.
207 
208   // Target Options
209   Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
210   Opts.CPU = Args.getLastArgValue(OPT_target_cpu);
211   Opts.Features = Args.getAllArgValues(OPT_target_feature);
212 
213   // Use the default target triple if unspecified.
214   if (Opts.Triple.empty())
215     Opts.Triple = llvm::sys::getDefaultTargetTriple();
216 
217   // Language Options
218   Opts.IncludePaths = Args.getAllArgValues(OPT_I);
219   Opts.NoInitialTextSection = Args.hasArg(OPT_n);
220   Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
221   // Any DebugInfoKind implies GenDwarfForAssembly.
222   Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
223 
224   if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections,
225                                      OPT_compress_debug_sections_EQ)) {
226     if (A->getOption().getID() == OPT_compress_debug_sections) {
227       // TODO: be more clever about the compression type auto-detection
228       Opts.CompressDebugSections = llvm::DebugCompressionType::GNU;
229     } else {
230       Opts.CompressDebugSections =
231           llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
232               .Case("none", llvm::DebugCompressionType::None)
233               .Case("zlib", llvm::DebugCompressionType::Z)
234               .Case("zlib-gnu", llvm::DebugCompressionType::GNU)
235               .Default(llvm::DebugCompressionType::None);
236     }
237   }
238 
239   Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
240   Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
241   Opts.DwarfDebugFlags = Args.getLastArgValue(OPT_dwarf_debug_flags);
242   Opts.DwarfDebugProducer = Args.getLastArgValue(OPT_dwarf_debug_producer);
243   Opts.DebugCompilationDir = Args.getLastArgValue(OPT_fdebug_compilation_dir);
244   Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
245 
246   for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ))
247     Opts.DebugPrefixMap.insert(StringRef(Arg).split('='));
248 
249   // Frontend Options
250   if (Args.hasArg(OPT_INPUT)) {
251     bool First = true;
252     for (const Arg *A : Args.filtered(OPT_INPUT)) {
253       if (First) {
254         Opts.InputFile = A->getValue();
255         First = false;
256       } else {
257         Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
258         Success = false;
259       }
260     }
261   }
262   Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
263   Opts.OutputPath = Args.getLastArgValue(OPT_o);
264   Opts.SplitDwarfOutput = Args.getLastArgValue(OPT_split_dwarf_output);
265   if (Arg *A = Args.getLastArg(OPT_filetype)) {
266     StringRef Name = A->getValue();
267     unsigned OutputType = StringSwitch<unsigned>(Name)
268       .Case("asm", FT_Asm)
269       .Case("null", FT_Null)
270       .Case("obj", FT_Obj)
271       .Default(~0U);
272     if (OutputType == ~0U) {
273       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
274       Success = false;
275     } else
276       Opts.OutputType = FileType(OutputType);
277   }
278   Opts.ShowHelp = Args.hasArg(OPT_help);
279   Opts.ShowVersion = Args.hasArg(OPT_version);
280 
281   // Transliterate Options
282   Opts.OutputAsmVariant =
283       getLastArgIntValue(Args, OPT_output_asm_variant, 0, Diags);
284   Opts.ShowEncoding = Args.hasArg(OPT_show_encoding);
285   Opts.ShowInst = Args.hasArg(OPT_show_inst);
286 
287   // Assemble Options
288   Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
289   Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
290   Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
291   Opts.NoWarn = Args.hasArg(OPT_massembler_no_warn);
292   Opts.RelocationModel = Args.getLastArgValue(OPT_mrelocation_model, "pic");
293   Opts.TargetABI = Args.getLastArgValue(OPT_target_abi);
294   Opts.IncrementalLinkerCompatible =
295       Args.hasArg(OPT_mincremental_linker_compatible);
296   Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
297 
298   // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
299   // EmbedBitcode behaves the same for all embed options for assembly files.
300   if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
301     Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
302                             .Case("all", 1)
303                             .Case("bitcode", 1)
304                             .Case("marker", 1)
305                             .Default(0);
306   }
307 
308   return Success;
309 }
310 
311 static std::unique_ptr<raw_fd_ostream>
312 getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
313   // Make sure that the Out file gets unlinked from the disk if we get a
314   // SIGINT.
315   if (Path != "-")
316     sys::RemoveFileOnSignal(Path);
317 
318   std::error_code EC;
319   auto Out = std::make_unique<raw_fd_ostream>(
320       Path, EC, (Binary ? sys::fs::OF_None : sys::fs::OF_Text));
321   if (EC) {
322     Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
323     return nullptr;
324   }
325 
326   return Out;
327 }
328 
329 static bool ExecuteAssembler(AssemblerInvocation &Opts,
330                              DiagnosticsEngine &Diags) {
331   // Get the target specific parser.
332   std::string Error;
333   const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
334   if (!TheTarget)
335     return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
336 
337   ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
338       MemoryBuffer::getFileOrSTDIN(Opts.InputFile);
339 
340   if (std::error_code EC = Buffer.getError()) {
341     Error = EC.message();
342     return Diags.Report(diag::err_fe_error_reading) << Opts.InputFile;
343   }
344 
345   SourceMgr SrcMgr;
346 
347   // Tell SrcMgr about this buffer, which is what the parser will pick up.
348   unsigned BufferIndex = SrcMgr.AddNewSourceBuffer(std::move(*Buffer), SMLoc());
349 
350   // Record the location of the include directories so that the lexer can find
351   // it later.
352   SrcMgr.setIncludeDirs(Opts.IncludePaths);
353 
354   std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
355   assert(MRI && "Unable to create target register info!");
356 
357   MCTargetOptions MCOptions;
358   std::unique_ptr<MCAsmInfo> MAI(
359       TheTarget->createMCAsmInfo(*MRI, Opts.Triple, MCOptions));
360   assert(MAI && "Unable to create target asm info!");
361 
362   // Ensure MCAsmInfo initialization occurs before any use, otherwise sections
363   // may be created with a combination of default and explicit settings.
364   MAI->setCompressDebugSections(Opts.CompressDebugSections);
365 
366   MAI->setRelaxELFRelocations(Opts.RelaxELFRelocations);
367 
368   bool IsBinary = Opts.OutputType == AssemblerInvocation::FT_Obj;
369   if (Opts.OutputPath.empty())
370     Opts.OutputPath = "-";
371   std::unique_ptr<raw_fd_ostream> FDOS =
372       getOutputStream(Opts.OutputPath, Diags, IsBinary);
373   if (!FDOS)
374     return true;
375   std::unique_ptr<raw_fd_ostream> DwoOS;
376   if (!Opts.SplitDwarfOutput.empty())
377     DwoOS = getOutputStream(Opts.SplitDwarfOutput, Diags, IsBinary);
378 
379   // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
380   // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
381   std::unique_ptr<MCObjectFileInfo> MOFI(new MCObjectFileInfo());
382 
383   MCContext Ctx(MAI.get(), MRI.get(), MOFI.get(), &SrcMgr, &MCOptions);
384 
385   bool PIC = false;
386   if (Opts.RelocationModel == "static") {
387     PIC = false;
388   } else if (Opts.RelocationModel == "pic") {
389     PIC = true;
390   } else {
391     assert(Opts.RelocationModel == "dynamic-no-pic" &&
392            "Invalid PIC model!");
393     PIC = false;
394   }
395 
396   MOFI->InitMCObjectFileInfo(Triple(Opts.Triple), PIC, Ctx);
397   if (Opts.SaveTemporaryLabels)
398     Ctx.setAllowTemporaryLabels(false);
399   if (Opts.GenDwarfForAssembly)
400     Ctx.setGenDwarfForAssembly(true);
401   if (!Opts.DwarfDebugFlags.empty())
402     Ctx.setDwarfDebugFlags(StringRef(Opts.DwarfDebugFlags));
403   if (!Opts.DwarfDebugProducer.empty())
404     Ctx.setDwarfDebugProducer(StringRef(Opts.DwarfDebugProducer));
405   if (!Opts.DebugCompilationDir.empty())
406     Ctx.setCompilationDir(Opts.DebugCompilationDir);
407   else {
408     // If no compilation dir is set, try to use the current directory.
409     SmallString<128> CWD;
410     if (!sys::fs::current_path(CWD))
411       Ctx.setCompilationDir(CWD);
412   }
413   if (!Opts.DebugPrefixMap.empty())
414     for (const auto &KV : Opts.DebugPrefixMap)
415       Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
416   if (!Opts.MainFileName.empty())
417     Ctx.setMainFileName(StringRef(Opts.MainFileName));
418   Ctx.setDwarfVersion(Opts.DwarfVersion);
419   if (Opts.GenDwarfForAssembly)
420     Ctx.setGenDwarfRootFile(Opts.InputFile,
421                             SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());
422 
423   // Build up the feature string from the target feature list.
424   std::string FS;
425   if (!Opts.Features.empty()) {
426     FS = Opts.Features[0];
427     for (unsigned i = 1, e = Opts.Features.size(); i != e; ++i)
428       FS += "," + Opts.Features[i];
429   }
430 
431   std::unique_ptr<MCStreamer> Str;
432 
433   std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
434   std::unique_ptr<MCSubtargetInfo> STI(
435       TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
436 
437   raw_pwrite_stream *Out = FDOS.get();
438   std::unique_ptr<buffer_ostream> BOS;
439 
440   MCOptions.MCNoWarn = Opts.NoWarn;
441   MCOptions.MCFatalWarnings = Opts.FatalWarnings;
442   MCOptions.ABIName = Opts.TargetABI;
443 
444   // FIXME: There is a bit of code duplication with addPassesToEmitFile.
445   if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
446     MCInstPrinter *IP = TheTarget->createMCInstPrinter(
447         llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
448 
449     std::unique_ptr<MCCodeEmitter> CE;
450     if (Opts.ShowEncoding)
451       CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
452     std::unique_ptr<MCAsmBackend> MAB(
453         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
454 
455     auto FOut = std::make_unique<formatted_raw_ostream>(*Out);
456     Str.reset(TheTarget->createAsmStreamer(
457         Ctx, std::move(FOut), /*asmverbose*/ true,
458         /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
459         Opts.ShowInst));
460   } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
461     Str.reset(createNullStreamer(Ctx));
462   } else {
463     assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
464            "Invalid file type!");
465     if (!FDOS->supportsSeeking()) {
466       BOS = std::make_unique<buffer_ostream>(*FDOS);
467       Out = BOS.get();
468     }
469 
470     std::unique_ptr<MCCodeEmitter> CE(
471         TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
472     std::unique_ptr<MCAsmBackend> MAB(
473         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
474     std::unique_ptr<MCObjectWriter> OW =
475         DwoOS ? MAB->createDwoObjectWriter(*Out, *DwoOS)
476               : MAB->createObjectWriter(*Out);
477 
478     Triple T(Opts.Triple);
479     Str.reset(TheTarget->createMCObjectStreamer(
480         T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI,
481         Opts.RelaxAll, Opts.IncrementalLinkerCompatible,
482         /*DWARFMustBeAtTheEnd*/ true));
483     Str.get()->InitSections(Opts.NoExecStack);
484   }
485 
486   // When -fembed-bitcode is passed to clang_as, a 1-byte marker
487   // is emitted in __LLVM,__asm section if the object file is MachO format.
488   if (Opts.EmbedBitcode && Ctx.getObjectFileInfo()->getObjectFileType() ==
489                                MCObjectFileInfo::IsMachO) {
490     MCSection *AsmLabel = Ctx.getMachOSection(
491         "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
492     Str.get()->SwitchSection(AsmLabel);
493     Str.get()->EmitZeros(1);
494   }
495 
496   // Assembly to object compilation should leverage assembly info.
497   Str->setUseAssemblerInfoForParsing(true);
498 
499   bool Failed = false;
500 
501   std::unique_ptr<MCAsmParser> Parser(
502       createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
503 
504   // FIXME: init MCTargetOptions from sanitizer flags here.
505   std::unique_ptr<MCTargetAsmParser> TAP(
506       TheTarget->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
507   if (!TAP)
508     Failed = Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
509 
510   // Set values for symbols, if any.
511   for (auto &S : Opts.SymbolDefs) {
512     auto Pair = StringRef(S).split('=');
513     auto Sym = Pair.first;
514     auto Val = Pair.second;
515     int64_t Value;
516     // We have already error checked this in the driver.
517     Val.getAsInteger(0, Value);
518     Ctx.setSymbolValue(Parser->getStreamer(), Sym, Value);
519   }
520 
521   if (!Failed) {
522     Parser->setTargetParser(*TAP.get());
523     Failed = Parser->Run(Opts.NoInitialTextSection);
524   }
525 
526   // Close Streamer first.
527   // It might have a reference to the output stream.
528   Str.reset();
529   // Close the output stream early.
530   BOS.reset();
531   FDOS.reset();
532 
533   // Delete output file if there were errors.
534   if (Failed) {
535     if (Opts.OutputPath != "-")
536       sys::fs::remove(Opts.OutputPath);
537     if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
538       sys::fs::remove(Opts.SplitDwarfOutput);
539   }
540 
541   return Failed;
542 }
543 
544 static void LLVMErrorHandler(void *UserData, const std::string &Message,
545                              bool GenCrashDiag) {
546   DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
547 
548   Diags.Report(diag::err_fe_error_backend) << Message;
549 
550   // We cannot recover from llvm errors.
551   sys::Process::Exit(1);
552 }
553 
554 int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
555   // Initialize targets and assembly printers/parsers.
556   InitializeAllTargetInfos();
557   InitializeAllTargetMCs();
558   InitializeAllAsmParsers();
559 
560   // Construct our diagnostic client.
561   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
562   TextDiagnosticPrinter *DiagClient
563     = new TextDiagnosticPrinter(errs(), &*DiagOpts);
564   DiagClient->setPrefix("clang -cc1as");
565   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
566   DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
567 
568   // Set an error handler, so that any LLVM backend diagnostics go through our
569   // error handler.
570   ScopedFatalErrorHandler FatalErrorHandler
571     (LLVMErrorHandler, static_cast<void*>(&Diags));
572 
573   // Parse the arguments.
574   AssemblerInvocation Asm;
575   if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
576     return 1;
577 
578   if (Asm.ShowHelp) {
579     getDriverOptTable().PrintHelp(
580         llvm::outs(), "clang -cc1as [options] file...",
581         "Clang Integrated Assembler",
582         /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
583         /*ShowAllAliases=*/false);
584     return 0;
585   }
586 
587   // Honor -version.
588   //
589   // FIXME: Use a better -version message?
590   if (Asm.ShowVersion) {
591     llvm::cl::PrintVersionMessage();
592     return 0;
593   }
594 
595   // Honor -mllvm.
596   //
597   // FIXME: Remove this, one day.
598   if (!Asm.LLVMArgs.empty()) {
599     unsigned NumArgs = Asm.LLVMArgs.size();
600     auto Args = std::make_unique<const char*[]>(NumArgs + 2);
601     Args[0] = "clang (LLVM option parsing)";
602     for (unsigned i = 0; i != NumArgs; ++i)
603       Args[i + 1] = Asm.LLVMArgs[i].c_str();
604     Args[NumArgs + 1] = nullptr;
605     llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
606   }
607 
608   // Execute the invocation, unless there were parsing errors.
609   bool Failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
610 
611   // If any timers were active but haven't been destroyed yet, print their
612   // results now.
613   TimerGroup::printAll(errs());
614   TimerGroup::clearAll();
615 
616   return !!Failed;
617 }
618