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 Dwarf64 : 1;
95   unsigned DwarfVersion;
96   std::string DwarfDebugFlags;
97   std::string DwarfDebugProducer;
98   std::string DebugCompilationDir;
99   std::map<const std::string, const std::string> DebugPrefixMap;
100   llvm::DebugCompressionType CompressDebugSections =
101       llvm::DebugCompressionType::None;
102   std::string MainFileName;
103   std::string SplitDwarfOutput;
104 
105   /// @}
106   /// @name Frontend Options
107   /// @{
108 
109   std::string InputFile;
110   std::vector<std::string> LLVMArgs;
111   std::string OutputPath;
112   enum FileType {
113     FT_Asm,  ///< Assembly (.s) output, transliterate mode.
114     FT_Null, ///< No output, for timing purposes.
115     FT_Obj   ///< Object file output.
116   };
117   FileType OutputType;
118   unsigned ShowHelp : 1;
119   unsigned ShowVersion : 1;
120 
121   /// @}
122   /// @name Transliterate Options
123   /// @{
124 
125   unsigned OutputAsmVariant;
126   unsigned ShowEncoding : 1;
127   unsigned ShowInst : 1;
128 
129   /// @}
130   /// @name Assembler Options
131   /// @{
132 
133   unsigned RelaxAll : 1;
134   unsigned NoExecStack : 1;
135   unsigned FatalWarnings : 1;
136   unsigned NoWarn : 1;
137   unsigned IncrementalLinkerCompatible : 1;
138   unsigned EmbedBitcode : 1;
139 
140   /// The name of the relocation model to use.
141   std::string RelocationModel;
142 
143   /// The ABI targeted by the backend. Specified using -target-abi. Empty
144   /// otherwise.
145   std::string TargetABI;
146 
147   /// @}
148 
149 public:
150   AssemblerInvocation() {
151     Triple = "";
152     NoInitialTextSection = 0;
153     InputFile = "-";
154     OutputPath = "-";
155     OutputType = FT_Asm;
156     OutputAsmVariant = 0;
157     ShowInst = 0;
158     ShowEncoding = 0;
159     RelaxAll = 0;
160     NoExecStack = 0;
161     FatalWarnings = 0;
162     NoWarn = 0;
163     IncrementalLinkerCompatible = 0;
164     Dwarf64 = 0;
165     DwarfVersion = 0;
166     EmbedBitcode = 0;
167   }
168 
169   static bool CreateFromArgs(AssemblerInvocation &Res,
170                              ArrayRef<const char *> Argv,
171                              DiagnosticsEngine &Diags);
172 };
173 
174 }
175 
176 bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
177                                          ArrayRef<const char *> Argv,
178                                          DiagnosticsEngine &Diags) {
179   bool Success = true;
180 
181   // Parse the arguments.
182   const OptTable &OptTbl = getDriverOptTable();
183 
184   const unsigned IncludedFlagsBitmask = options::CC1AsOption;
185   unsigned MissingArgIndex, MissingArgCount;
186   InputArgList Args = OptTbl.ParseArgs(Argv, MissingArgIndex, MissingArgCount,
187                                        IncludedFlagsBitmask);
188 
189   // Check for missing argument error.
190   if (MissingArgCount) {
191     Diags.Report(diag::err_drv_missing_argument)
192         << Args.getArgString(MissingArgIndex) << MissingArgCount;
193     Success = false;
194   }
195 
196   // Issue errors on unknown arguments.
197   for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
198     auto ArgString = A->getAsString(Args);
199     std::string Nearest;
200     if (OptTbl.findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
201       Diags.Report(diag::err_drv_unknown_argument) << ArgString;
202     else
203       Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
204           << ArgString << Nearest;
205     Success = false;
206   }
207 
208   // Construct the invocation.
209 
210   // Target Options
211   Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
212   Opts.CPU = std::string(Args.getLastArgValue(OPT_target_cpu));
213   Opts.Features = Args.getAllArgValues(OPT_target_feature);
214 
215   // Use the default target triple if unspecified.
216   if (Opts.Triple.empty())
217     Opts.Triple = llvm::sys::getDefaultTargetTriple();
218 
219   // Language Options
220   Opts.IncludePaths = Args.getAllArgValues(OPT_I);
221   Opts.NoInitialTextSection = Args.hasArg(OPT_n);
222   Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
223   // Any DebugInfoKind implies GenDwarfForAssembly.
224   Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
225 
226   if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections_EQ)) {
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   Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
236   if (auto *DwarfFormatArg = Args.getLastArg(OPT_gdwarf64, OPT_gdwarf32))
237     Opts.Dwarf64 = DwarfFormatArg->getOption().matches(OPT_gdwarf64);
238   Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
239   Opts.DwarfDebugFlags =
240       std::string(Args.getLastArgValue(OPT_dwarf_debug_flags));
241   Opts.DwarfDebugProducer =
242       std::string(Args.getLastArgValue(OPT_dwarf_debug_producer));
243   if (const Arg *A = Args.getLastArg(options::OPT_ffile_compilation_dir_EQ,
244                                      options::OPT_fdebug_compilation_dir_EQ))
245     Opts.DebugCompilationDir = A->getValue();
246   Opts.MainFileName = std::string(Args.getLastArgValue(OPT_main_file_name));
247 
248   for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ)) {
249     auto Split = StringRef(Arg).split('=');
250     Opts.DebugPrefixMap.insert(
251         {std::string(Split.first), std::string(Split.second)});
252   }
253 
254   // Frontend Options
255   if (Args.hasArg(OPT_INPUT)) {
256     bool First = true;
257     for (const Arg *A : Args.filtered(OPT_INPUT)) {
258       if (First) {
259         Opts.InputFile = A->getValue();
260         First = false;
261       } else {
262         Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
263         Success = false;
264       }
265     }
266   }
267   Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
268   Opts.OutputPath = std::string(Args.getLastArgValue(OPT_o));
269   Opts.SplitDwarfOutput =
270       std::string(Args.getLastArgValue(OPT_split_dwarf_output));
271   if (Arg *A = Args.getLastArg(OPT_filetype)) {
272     StringRef Name = A->getValue();
273     unsigned OutputType = StringSwitch<unsigned>(Name)
274       .Case("asm", FT_Asm)
275       .Case("null", FT_Null)
276       .Case("obj", FT_Obj)
277       .Default(~0U);
278     if (OutputType == ~0U) {
279       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
280       Success = false;
281     } else
282       Opts.OutputType = FileType(OutputType);
283   }
284   Opts.ShowHelp = Args.hasArg(OPT_help);
285   Opts.ShowVersion = Args.hasArg(OPT_version);
286 
287   // Transliterate Options
288   Opts.OutputAsmVariant =
289       getLastArgIntValue(Args, OPT_output_asm_variant, 0, Diags);
290   Opts.ShowEncoding = Args.hasArg(OPT_show_encoding);
291   Opts.ShowInst = Args.hasArg(OPT_show_inst);
292 
293   // Assemble Options
294   Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
295   Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
296   Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
297   Opts.NoWarn = Args.hasArg(OPT_massembler_no_warn);
298   Opts.RelocationModel =
299       std::string(Args.getLastArgValue(OPT_mrelocation_model, "pic"));
300   Opts.TargetABI = std::string(Args.getLastArgValue(OPT_target_abi));
301   Opts.IncrementalLinkerCompatible =
302       Args.hasArg(OPT_mincremental_linker_compatible);
303   Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
304 
305   // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
306   // EmbedBitcode behaves the same for all embed options for assembly files.
307   if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
308     Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
309                             .Case("all", 1)
310                             .Case("bitcode", 1)
311                             .Case("marker", 1)
312                             .Default(0);
313   }
314 
315   return Success;
316 }
317 
318 static std::unique_ptr<raw_fd_ostream>
319 getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
320   // Make sure that the Out file gets unlinked from the disk if we get a
321   // SIGINT.
322   if (Path != "-")
323     sys::RemoveFileOnSignal(Path);
324 
325   std::error_code EC;
326   auto Out = std::make_unique<raw_fd_ostream>(
327       Path, EC, (Binary ? sys::fs::OF_None : sys::fs::OF_TextWithCRLF));
328   if (EC) {
329     Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
330     return nullptr;
331   }
332 
333   return Out;
334 }
335 
336 static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,
337                                  DiagnosticsEngine &Diags) {
338   // Get the target specific parser.
339   std::string Error;
340   const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
341   if (!TheTarget)
342     return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
343 
344   ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
345       MemoryBuffer::getFileOrSTDIN(Opts.InputFile, /*IsText=*/true);
346 
347   if (std::error_code EC = Buffer.getError()) {
348     Error = EC.message();
349     return Diags.Report(diag::err_fe_error_reading) << Opts.InputFile;
350   }
351 
352   SourceMgr SrcMgr;
353 
354   // Tell SrcMgr about this buffer, which is what the parser will pick up.
355   unsigned BufferIndex = SrcMgr.AddNewSourceBuffer(std::move(*Buffer), SMLoc());
356 
357   // Record the location of the include directories so that the lexer can find
358   // it later.
359   SrcMgr.setIncludeDirs(Opts.IncludePaths);
360 
361   std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
362   assert(MRI && "Unable to create target register info!");
363 
364   MCTargetOptions MCOptions;
365   std::unique_ptr<MCAsmInfo> MAI(
366       TheTarget->createMCAsmInfo(*MRI, Opts.Triple, MCOptions));
367   assert(MAI && "Unable to create target asm info!");
368 
369   // Ensure MCAsmInfo initialization occurs before any use, otherwise sections
370   // may be created with a combination of default and explicit settings.
371   MAI->setCompressDebugSections(Opts.CompressDebugSections);
372 
373   MAI->setRelaxELFRelocations(Opts.RelaxELFRelocations);
374 
375   bool IsBinary = Opts.OutputType == AssemblerInvocation::FT_Obj;
376   if (Opts.OutputPath.empty())
377     Opts.OutputPath = "-";
378   std::unique_ptr<raw_fd_ostream> FDOS =
379       getOutputStream(Opts.OutputPath, Diags, IsBinary);
380   if (!FDOS)
381     return true;
382   std::unique_ptr<raw_fd_ostream> DwoOS;
383   if (!Opts.SplitDwarfOutput.empty())
384     DwoOS = getOutputStream(Opts.SplitDwarfOutput, Diags, IsBinary);
385 
386   // Build up the feature string from the target feature list.
387   std::string FS = llvm::join(Opts.Features, ",");
388 
389   std::unique_ptr<MCSubtargetInfo> STI(
390       TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
391   assert(STI && "Unable to create subtarget info!");
392 
393   MCContext Ctx(Triple(Opts.Triple), MAI.get(), MRI.get(), STI.get(), &SrcMgr,
394                 &MCOptions);
395 
396   bool PIC = false;
397   if (Opts.RelocationModel == "static") {
398     PIC = false;
399   } else if (Opts.RelocationModel == "pic") {
400     PIC = true;
401   } else {
402     assert(Opts.RelocationModel == "dynamic-no-pic" &&
403            "Invalid PIC model!");
404     PIC = false;
405   }
406 
407   // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
408   // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
409   std::unique_ptr<MCObjectFileInfo> MOFI(
410       TheTarget->createMCObjectFileInfo(Ctx, PIC));
411   Ctx.setObjectFileInfo(MOFI.get());
412 
413   if (Opts.SaveTemporaryLabels)
414     Ctx.setAllowTemporaryLabels(false);
415   if (Opts.GenDwarfForAssembly)
416     Ctx.setGenDwarfForAssembly(true);
417   if (!Opts.DwarfDebugFlags.empty())
418     Ctx.setDwarfDebugFlags(StringRef(Opts.DwarfDebugFlags));
419   if (!Opts.DwarfDebugProducer.empty())
420     Ctx.setDwarfDebugProducer(StringRef(Opts.DwarfDebugProducer));
421   if (!Opts.DebugCompilationDir.empty())
422     Ctx.setCompilationDir(Opts.DebugCompilationDir);
423   else {
424     // If no compilation dir is set, try to use the current directory.
425     SmallString<128> CWD;
426     if (!sys::fs::current_path(CWD))
427       Ctx.setCompilationDir(CWD);
428   }
429   if (!Opts.DebugPrefixMap.empty())
430     for (const auto &KV : Opts.DebugPrefixMap)
431       Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
432   if (!Opts.MainFileName.empty())
433     Ctx.setMainFileName(StringRef(Opts.MainFileName));
434   Ctx.setDwarfFormat(Opts.Dwarf64 ? dwarf::DWARF64 : dwarf::DWARF32);
435   Ctx.setDwarfVersion(Opts.DwarfVersion);
436   if (Opts.GenDwarfForAssembly)
437     Ctx.setGenDwarfRootFile(Opts.InputFile,
438                             SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());
439 
440   std::unique_ptr<MCStreamer> Str;
441 
442   std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
443   assert(MCII && "Unable to create instruction info!");
444 
445   raw_pwrite_stream *Out = FDOS.get();
446   std::unique_ptr<buffer_ostream> BOS;
447 
448   MCOptions.MCNoWarn = Opts.NoWarn;
449   MCOptions.MCFatalWarnings = Opts.FatalWarnings;
450   MCOptions.ABIName = Opts.TargetABI;
451 
452   // FIXME: There is a bit of code duplication with addPassesToEmitFile.
453   if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
454     MCInstPrinter *IP = TheTarget->createMCInstPrinter(
455         llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
456 
457     std::unique_ptr<MCCodeEmitter> CE;
458     if (Opts.ShowEncoding)
459       CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
460     std::unique_ptr<MCAsmBackend> MAB(
461         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
462 
463     auto FOut = std::make_unique<formatted_raw_ostream>(*Out);
464     Str.reset(TheTarget->createAsmStreamer(
465         Ctx, std::move(FOut), /*asmverbose*/ true,
466         /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
467         Opts.ShowInst));
468   } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
469     Str.reset(createNullStreamer(Ctx));
470   } else {
471     assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
472            "Invalid file type!");
473     if (!FDOS->supportsSeeking()) {
474       BOS = std::make_unique<buffer_ostream>(*FDOS);
475       Out = BOS.get();
476     }
477 
478     std::unique_ptr<MCCodeEmitter> CE(
479         TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
480     std::unique_ptr<MCAsmBackend> MAB(
481         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
482     assert(MAB && "Unable to create asm backend!");
483 
484     std::unique_ptr<MCObjectWriter> OW =
485         DwoOS ? MAB->createDwoObjectWriter(*Out, *DwoOS)
486               : MAB->createObjectWriter(*Out);
487 
488     Triple T(Opts.Triple);
489     Str.reset(TheTarget->createMCObjectStreamer(
490         T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI,
491         Opts.RelaxAll, Opts.IncrementalLinkerCompatible,
492         /*DWARFMustBeAtTheEnd*/ true));
493     Str.get()->InitSections(Opts.NoExecStack);
494   }
495 
496   // When -fembed-bitcode is passed to clang_as, a 1-byte marker
497   // is emitted in __LLVM,__asm section if the object file is MachO format.
498   if (Opts.EmbedBitcode && Ctx.getObjectFileType() == MCContext::IsMachO) {
499     MCSection *AsmLabel = Ctx.getMachOSection(
500         "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
501     Str.get()->SwitchSection(AsmLabel);
502     Str.get()->emitZeros(1);
503   }
504 
505   // Assembly to object compilation should leverage assembly info.
506   Str->setUseAssemblerInfoForParsing(true);
507 
508   bool Failed = false;
509 
510   std::unique_ptr<MCAsmParser> Parser(
511       createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
512 
513   // FIXME: init MCTargetOptions from sanitizer flags here.
514   std::unique_ptr<MCTargetAsmParser> TAP(
515       TheTarget->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
516   if (!TAP)
517     Failed = Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
518 
519   // Set values for symbols, if any.
520   for (auto &S : Opts.SymbolDefs) {
521     auto Pair = StringRef(S).split('=');
522     auto Sym = Pair.first;
523     auto Val = Pair.second;
524     int64_t Value;
525     // We have already error checked this in the driver.
526     Val.getAsInteger(0, Value);
527     Ctx.setSymbolValue(Parser->getStreamer(), Sym, Value);
528   }
529 
530   if (!Failed) {
531     Parser->setTargetParser(*TAP.get());
532     Failed = Parser->Run(Opts.NoInitialTextSection);
533   }
534 
535   return Failed;
536 }
537 
538 static bool ExecuteAssembler(AssemblerInvocation &Opts,
539                              DiagnosticsEngine &Diags) {
540   bool Failed = ExecuteAssemblerImpl(Opts, Diags);
541 
542   // Delete output file if there were errors.
543   if (Failed) {
544     if (Opts.OutputPath != "-")
545       sys::fs::remove(Opts.OutputPath);
546     if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
547       sys::fs::remove(Opts.SplitDwarfOutput);
548   }
549 
550   return Failed;
551 }
552 
553 static void LLVMErrorHandler(void *UserData, const std::string &Message,
554                              bool GenCrashDiag) {
555   DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
556 
557   Diags.Report(diag::err_fe_error_backend) << Message;
558 
559   // We cannot recover from llvm errors.
560   sys::Process::Exit(1);
561 }
562 
563 int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
564   // Initialize targets and assembly printers/parsers.
565   InitializeAllTargetInfos();
566   InitializeAllTargetMCs();
567   InitializeAllAsmParsers();
568 
569   // Construct our diagnostic client.
570   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
571   TextDiagnosticPrinter *DiagClient
572     = new TextDiagnosticPrinter(errs(), &*DiagOpts);
573   DiagClient->setPrefix("clang -cc1as");
574   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
575   DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
576 
577   // Set an error handler, so that any LLVM backend diagnostics go through our
578   // error handler.
579   ScopedFatalErrorHandler FatalErrorHandler
580     (LLVMErrorHandler, static_cast<void*>(&Diags));
581 
582   // Parse the arguments.
583   AssemblerInvocation Asm;
584   if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
585     return 1;
586 
587   if (Asm.ShowHelp) {
588     getDriverOptTable().printHelp(
589         llvm::outs(), "clang -cc1as [options] file...",
590         "Clang Integrated Assembler",
591         /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
592         /*ShowAllAliases=*/false);
593     return 0;
594   }
595 
596   // Honor -version.
597   //
598   // FIXME: Use a better -version message?
599   if (Asm.ShowVersion) {
600     llvm::cl::PrintVersionMessage();
601     return 0;
602   }
603 
604   // Honor -mllvm.
605   //
606   // FIXME: Remove this, one day.
607   if (!Asm.LLVMArgs.empty()) {
608     unsigned NumArgs = Asm.LLVMArgs.size();
609     auto Args = std::make_unique<const char*[]>(NumArgs + 2);
610     Args[0] = "clang (LLVM option parsing)";
611     for (unsigned i = 0; i != NumArgs; ++i)
612       Args[i + 1] = Asm.LLVMArgs[i].c_str();
613     Args[NumArgs + 1] = nullptr;
614     llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
615   }
616 
617   // Execute the invocation, unless there were parsing errors.
618   bool Failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
619 
620   // If any timers were active but haven't been destroyed yet, print their
621   // results now.
622   TimerGroup::printAll(errs());
623   TimerGroup::clearAll();
624 
625   return !!Failed;
626 }
627