xref: /freebsd/contrib/llvm-project/clang/tools/driver/cc1as_main.cpp (revision a90b9d0159070121c221b966469c3e36d912bf82) 
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/StringExtras.h"
23 #include "llvm/ADT/StringSwitch.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/MC/TargetRegistry.h"
40 #include "llvm/Option/Arg.h"
41 #include "llvm/Option/ArgList.h"
42 #include "llvm/Option/OptTable.h"
43 #include "llvm/Support/CommandLine.h"
44 #include "llvm/Support/ErrorHandling.h"
45 #include "llvm/Support/FileSystem.h"
46 #include "llvm/Support/FormattedStream.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/TargetSelect.h"
53 #include "llvm/Support/Timer.h"
54 #include "llvm/Support/raw_ostream.h"
55 #include "llvm/TargetParser/Host.h"
56 #include "llvm/TargetParser/Triple.h"
57 #include <memory>
58 #include <optional>
59 #include <system_error>
60 using namespace clang;
61 using namespace clang::driver;
62 using namespace clang::driver::options;
63 using namespace llvm;
64 using namespace llvm::opt;
65 
66 namespace {
67 
68 /// Helper class for representing a single invocation of the assembler.
69 struct AssemblerInvocation {
70   /// @name Target Options
71   /// @{
72 
73   /// The name of the target triple to assemble for.
74   std::string Triple;
75 
76   /// If given, the name of the target CPU to determine which instructions
77   /// are legal.
78   std::string CPU;
79 
80   /// The list of target specific features to enable or disable -- this should
81   /// be a list of strings starting with '+' or '-'.
82   std::vector<std::string> Features;
83 
84   /// The list of symbol definitions.
85   std::vector<std::string> SymbolDefs;
86 
87   /// @}
88   /// @name Language Options
89   /// @{
90 
91   std::vector<std::string> IncludePaths;
92   unsigned NoInitialTextSection : 1;
93   unsigned SaveTemporaryLabels : 1;
94   unsigned GenDwarfForAssembly : 1;
95   unsigned RelaxELFRelocations : 1;
96   unsigned Dwarf64 : 1;
97   unsigned DwarfVersion;
98   std::string DwarfDebugFlags;
99   std::string DwarfDebugProducer;
100   std::string DebugCompilationDir;
101   llvm::SmallVector<std::pair<std::string, std::string>, 0> DebugPrefixMap;
102   llvm::DebugCompressionType CompressDebugSections =
103       llvm::DebugCompressionType::None;
104   std::string MainFileName;
105   std::string SplitDwarfOutput;
106 
107   /// @}
108   /// @name Frontend Options
109   /// @{
110 
111   std::string InputFile;
112   std::vector<std::string> LLVMArgs;
113   std::string OutputPath;
114   enum FileType {
115     FT_Asm,  ///< Assembly (.s) output, transliterate mode.
116     FT_Null, ///< No output, for timing purposes.
117     FT_Obj   ///< Object file output.
118   };
119   FileType OutputType;
120   unsigned ShowHelp : 1;
121   unsigned ShowVersion : 1;
122 
123   /// @}
124   /// @name Transliterate Options
125   /// @{
126 
127   unsigned OutputAsmVariant;
128   unsigned ShowEncoding : 1;
129   unsigned ShowInst : 1;
130 
131   /// @}
132   /// @name Assembler Options
133   /// @{
134 
135   unsigned RelaxAll : 1;
136   unsigned NoExecStack : 1;
137   unsigned FatalWarnings : 1;
138   unsigned NoWarn : 1;
139   unsigned NoTypeCheck : 1;
140   unsigned IncrementalLinkerCompatible : 1;
141   unsigned EmbedBitcode : 1;
142 
143   /// Whether to emit DWARF unwind info.
144   EmitDwarfUnwindType EmitDwarfUnwind;
145 
146   // Whether to emit compact-unwind for non-canonical entries.
147   // Note: maybe overriden by other constraints.
148   unsigned EmitCompactUnwindNonCanonical : 1;
149 
150   /// The name of the relocation model to use.
151   std::string RelocationModel;
152 
153   /// The ABI targeted by the backend. Specified using -target-abi. Empty
154   /// otherwise.
155   std::string TargetABI;
156 
157   /// Darwin target variant triple, the variant of the deployment target
158   /// for which the code is being compiled.
159   std::optional<llvm::Triple> DarwinTargetVariantTriple;
160 
161   /// The version of the darwin target variant SDK which was used during the
162   /// compilation
163   llvm::VersionTuple DarwinTargetVariantSDKVersion;
164 
165   /// The name of a file to use with \c .secure_log_unique directives.
166   std::string AsSecureLogFile;
167   /// @}
168 
169 public:
170   AssemblerInvocation() {
171     Triple = "";
172     NoInitialTextSection = 0;
173     InputFile = "-";
174     OutputPath = "-";
175     OutputType = FT_Asm;
176     OutputAsmVariant = 0;
177     ShowInst = 0;
178     ShowEncoding = 0;
179     RelaxAll = 0;
180     NoExecStack = 0;
181     FatalWarnings = 0;
182     NoWarn = 0;
183     NoTypeCheck = 0;
184     IncrementalLinkerCompatible = 0;
185     Dwarf64 = 0;
186     DwarfVersion = 0;
187     EmbedBitcode = 0;
188     EmitDwarfUnwind = EmitDwarfUnwindType::Default;
189     EmitCompactUnwindNonCanonical = false;
190   }
191 
192   static bool CreateFromArgs(AssemblerInvocation &Res,
193                              ArrayRef<const char *> Argv,
194                              DiagnosticsEngine &Diags);
195 };
196 
197 }
198 
199 bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
200                                          ArrayRef<const char *> Argv,
201                                          DiagnosticsEngine &Diags) {
202   bool Success = true;
203 
204   // Parse the arguments.
205   const OptTable &OptTbl = getDriverOptTable();
206 
207   llvm::opt::Visibility VisibilityMask(options::CC1AsOption);
208   unsigned MissingArgIndex, MissingArgCount;
209   InputArgList Args =
210       OptTbl.ParseArgs(Argv, MissingArgIndex, MissingArgCount, VisibilityMask);
211 
212   // Check for missing argument error.
213   if (MissingArgCount) {
214     Diags.Report(diag::err_drv_missing_argument)
215         << Args.getArgString(MissingArgIndex) << MissingArgCount;
216     Success = false;
217   }
218 
219   // Issue errors on unknown arguments.
220   for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
221     auto ArgString = A->getAsString(Args);
222     std::string Nearest;
223     if (OptTbl.findNearest(ArgString, Nearest, VisibilityMask) > 1)
224       Diags.Report(diag::err_drv_unknown_argument) << ArgString;
225     else
226       Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
227           << ArgString << Nearest;
228     Success = false;
229   }
230 
231   // Construct the invocation.
232 
233   // Target Options
234   Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
235   if (Arg *A = Args.getLastArg(options::OPT_darwin_target_variant_triple))
236     Opts.DarwinTargetVariantTriple = llvm::Triple(A->getValue());
237   if (Arg *A = Args.getLastArg(OPT_darwin_target_variant_sdk_version_EQ)) {
238     VersionTuple Version;
239     if (Version.tryParse(A->getValue()))
240       Diags.Report(diag::err_drv_invalid_value)
241           << A->getAsString(Args) << A->getValue();
242     else
243       Opts.DarwinTargetVariantSDKVersion = Version;
244   }
245 
246   Opts.CPU = std::string(Args.getLastArgValue(OPT_target_cpu));
247   Opts.Features = Args.getAllArgValues(OPT_target_feature);
248 
249   // Use the default target triple if unspecified.
250   if (Opts.Triple.empty())
251     Opts.Triple = llvm::sys::getDefaultTargetTriple();
252 
253   // Language Options
254   Opts.IncludePaths = Args.getAllArgValues(OPT_I);
255   Opts.NoInitialTextSection = Args.hasArg(OPT_n);
256   Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
257   // Any DebugInfoKind implies GenDwarfForAssembly.
258   Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
259 
260   if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections_EQ)) {
261     Opts.CompressDebugSections =
262         llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
263             .Case("none", llvm::DebugCompressionType::None)
264             .Case("zlib", llvm::DebugCompressionType::Zlib)
265             .Case("zstd", llvm::DebugCompressionType::Zstd)
266             .Default(llvm::DebugCompressionType::None);
267   }
268 
269   Opts.RelaxELFRelocations = !Args.hasArg(OPT_mrelax_relocations_no);
270   if (auto *DwarfFormatArg = Args.getLastArg(OPT_gdwarf64, OPT_gdwarf32))
271     Opts.Dwarf64 = DwarfFormatArg->getOption().matches(OPT_gdwarf64);
272   Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
273   Opts.DwarfDebugFlags =
274       std::string(Args.getLastArgValue(OPT_dwarf_debug_flags));
275   Opts.DwarfDebugProducer =
276       std::string(Args.getLastArgValue(OPT_dwarf_debug_producer));
277   if (const Arg *A = Args.getLastArg(options::OPT_ffile_compilation_dir_EQ,
278                                      options::OPT_fdebug_compilation_dir_EQ))
279     Opts.DebugCompilationDir = A->getValue();
280   Opts.MainFileName = std::string(Args.getLastArgValue(OPT_main_file_name));
281 
282   for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ)) {
283     auto Split = StringRef(Arg).split('=');
284     Opts.DebugPrefixMap.emplace_back(Split.first, Split.second);
285   }
286 
287   // Frontend Options
288   if (Args.hasArg(OPT_INPUT)) {
289     bool First = true;
290     for (const Arg *A : Args.filtered(OPT_INPUT)) {
291       if (First) {
292         Opts.InputFile = A->getValue();
293         First = false;
294       } else {
295         Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
296         Success = false;
297       }
298     }
299   }
300   Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
301   Opts.OutputPath = std::string(Args.getLastArgValue(OPT_o));
302   Opts.SplitDwarfOutput =
303       std::string(Args.getLastArgValue(OPT_split_dwarf_output));
304   if (Arg *A = Args.getLastArg(OPT_filetype)) {
305     StringRef Name = A->getValue();
306     unsigned OutputType = StringSwitch<unsigned>(Name)
307       .Case("asm", FT_Asm)
308       .Case("null", FT_Null)
309       .Case("obj", FT_Obj)
310       .Default(~0U);
311     if (OutputType == ~0U) {
312       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
313       Success = false;
314     } else
315       Opts.OutputType = FileType(OutputType);
316   }
317   Opts.ShowHelp = Args.hasArg(OPT_help);
318   Opts.ShowVersion = Args.hasArg(OPT_version);
319 
320   // Transliterate Options
321   Opts.OutputAsmVariant =
322       getLastArgIntValue(Args, OPT_output_asm_variant, 0, Diags);
323   Opts.ShowEncoding = Args.hasArg(OPT_show_encoding);
324   Opts.ShowInst = Args.hasArg(OPT_show_inst);
325 
326   // Assemble Options
327   Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
328   Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
329   Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
330   Opts.NoWarn = Args.hasArg(OPT_massembler_no_warn);
331   Opts.NoTypeCheck = Args.hasArg(OPT_mno_type_check);
332   Opts.RelocationModel =
333       std::string(Args.getLastArgValue(OPT_mrelocation_model, "pic"));
334   Opts.TargetABI = std::string(Args.getLastArgValue(OPT_target_abi));
335   Opts.IncrementalLinkerCompatible =
336       Args.hasArg(OPT_mincremental_linker_compatible);
337   Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
338 
339   // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
340   // EmbedBitcode behaves the same for all embed options for assembly files.
341   if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
342     Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
343                             .Case("all", 1)
344                             .Case("bitcode", 1)
345                             .Case("marker", 1)
346                             .Default(0);
347   }
348 
349   if (auto *A = Args.getLastArg(OPT_femit_dwarf_unwind_EQ)) {
350     Opts.EmitDwarfUnwind =
351         llvm::StringSwitch<EmitDwarfUnwindType>(A->getValue())
352             .Case("always", EmitDwarfUnwindType::Always)
353             .Case("no-compact-unwind", EmitDwarfUnwindType::NoCompactUnwind)
354             .Case("default", EmitDwarfUnwindType::Default);
355   }
356 
357   Opts.EmitCompactUnwindNonCanonical =
358       Args.hasArg(OPT_femit_compact_unwind_non_canonical);
359 
360   Opts.AsSecureLogFile = Args.getLastArgValue(OPT_as_secure_log_file);
361 
362   return Success;
363 }
364 
365 static std::unique_ptr<raw_fd_ostream>
366 getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
367   // Make sure that the Out file gets unlinked from the disk if we get a
368   // SIGINT.
369   if (Path != "-")
370     sys::RemoveFileOnSignal(Path);
371 
372   std::error_code EC;
373   auto Out = std::make_unique<raw_fd_ostream>(
374       Path, EC, (Binary ? sys::fs::OF_None : sys::fs::OF_TextWithCRLF));
375   if (EC) {
376     Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
377     return nullptr;
378   }
379 
380   return Out;
381 }
382 
383 static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,
384                                  DiagnosticsEngine &Diags) {
385   // Get the target specific parser.
386   std::string Error;
387   const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
388   if (!TheTarget)
389     return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
390 
391   ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
392       MemoryBuffer::getFileOrSTDIN(Opts.InputFile, /*IsText=*/true);
393 
394   if (std::error_code EC = Buffer.getError()) {
395     return Diags.Report(diag::err_fe_error_reading)
396            << Opts.InputFile << EC.message();
397   }
398 
399   SourceMgr SrcMgr;
400 
401   // Tell SrcMgr about this buffer, which is what the parser will pick up.
402   unsigned BufferIndex = SrcMgr.AddNewSourceBuffer(std::move(*Buffer), SMLoc());
403 
404   // Record the location of the include directories so that the lexer can find
405   // it later.
406   SrcMgr.setIncludeDirs(Opts.IncludePaths);
407 
408   std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
409   assert(MRI && "Unable to create target register info!");
410 
411   MCTargetOptions MCOptions;
412   MCOptions.EmitDwarfUnwind = Opts.EmitDwarfUnwind;
413   MCOptions.EmitCompactUnwindNonCanonical = Opts.EmitCompactUnwindNonCanonical;
414   MCOptions.AsSecureLogFile = Opts.AsSecureLogFile;
415 
416   std::unique_ptr<MCAsmInfo> MAI(
417       TheTarget->createMCAsmInfo(*MRI, Opts.Triple, MCOptions));
418   assert(MAI && "Unable to create target asm info!");
419 
420   // Ensure MCAsmInfo initialization occurs before any use, otherwise sections
421   // may be created with a combination of default and explicit settings.
422   MAI->setCompressDebugSections(Opts.CompressDebugSections);
423 
424   MAI->setRelaxELFRelocations(Opts.RelaxELFRelocations);
425 
426   bool IsBinary = Opts.OutputType == AssemblerInvocation::FT_Obj;
427   if (Opts.OutputPath.empty())
428     Opts.OutputPath = "-";
429   std::unique_ptr<raw_fd_ostream> FDOS =
430       getOutputStream(Opts.OutputPath, Diags, IsBinary);
431   if (!FDOS)
432     return true;
433   std::unique_ptr<raw_fd_ostream> DwoOS;
434   if (!Opts.SplitDwarfOutput.empty())
435     DwoOS = getOutputStream(Opts.SplitDwarfOutput, Diags, IsBinary);
436 
437   // Build up the feature string from the target feature list.
438   std::string FS = llvm::join(Opts.Features, ",");
439 
440   std::unique_ptr<MCSubtargetInfo> STI(
441       TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
442   assert(STI && "Unable to create subtarget info!");
443 
444   MCContext Ctx(Triple(Opts.Triple), MAI.get(), MRI.get(), STI.get(), &SrcMgr,
445                 &MCOptions);
446 
447   bool PIC = false;
448   if (Opts.RelocationModel == "static") {
449     PIC = false;
450   } else if (Opts.RelocationModel == "pic") {
451     PIC = true;
452   } else {
453     assert(Opts.RelocationModel == "dynamic-no-pic" &&
454            "Invalid PIC model!");
455     PIC = false;
456   }
457 
458   // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
459   // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
460   std::unique_ptr<MCObjectFileInfo> MOFI(
461       TheTarget->createMCObjectFileInfo(Ctx, PIC));
462   if (Opts.DarwinTargetVariantTriple)
463     MOFI->setDarwinTargetVariantTriple(*Opts.DarwinTargetVariantTriple);
464   if (!Opts.DarwinTargetVariantSDKVersion.empty())
465     MOFI->setDarwinTargetVariantSDKVersion(Opts.DarwinTargetVariantSDKVersion);
466   Ctx.setObjectFileInfo(MOFI.get());
467 
468   if (Opts.SaveTemporaryLabels)
469     Ctx.setAllowTemporaryLabels(false);
470   if (Opts.GenDwarfForAssembly)
471     Ctx.setGenDwarfForAssembly(true);
472   if (!Opts.DwarfDebugFlags.empty())
473     Ctx.setDwarfDebugFlags(StringRef(Opts.DwarfDebugFlags));
474   if (!Opts.DwarfDebugProducer.empty())
475     Ctx.setDwarfDebugProducer(StringRef(Opts.DwarfDebugProducer));
476   if (!Opts.DebugCompilationDir.empty())
477     Ctx.setCompilationDir(Opts.DebugCompilationDir);
478   else {
479     // If no compilation dir is set, try to use the current directory.
480     SmallString<128> CWD;
481     if (!sys::fs::current_path(CWD))
482       Ctx.setCompilationDir(CWD);
483   }
484   if (!Opts.DebugPrefixMap.empty())
485     for (const auto &KV : Opts.DebugPrefixMap)
486       Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
487   if (!Opts.MainFileName.empty())
488     Ctx.setMainFileName(StringRef(Opts.MainFileName));
489   Ctx.setDwarfFormat(Opts.Dwarf64 ? dwarf::DWARF64 : dwarf::DWARF32);
490   Ctx.setDwarfVersion(Opts.DwarfVersion);
491   if (Opts.GenDwarfForAssembly)
492     Ctx.setGenDwarfRootFile(Opts.InputFile,
493                             SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());
494 
495   std::unique_ptr<MCStreamer> Str;
496 
497   std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
498   assert(MCII && "Unable to create instruction info!");
499 
500   raw_pwrite_stream *Out = FDOS.get();
501   std::unique_ptr<buffer_ostream> BOS;
502 
503   MCOptions.MCNoWarn = Opts.NoWarn;
504   MCOptions.MCFatalWarnings = Opts.FatalWarnings;
505   MCOptions.MCNoTypeCheck = Opts.NoTypeCheck;
506   MCOptions.ABIName = Opts.TargetABI;
507 
508   // FIXME: There is a bit of code duplication with addPassesToEmitFile.
509   if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
510     MCInstPrinter *IP = TheTarget->createMCInstPrinter(
511         llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
512 
513     std::unique_ptr<MCCodeEmitter> CE;
514     if (Opts.ShowEncoding)
515       CE.reset(TheTarget->createMCCodeEmitter(*MCII, Ctx));
516     std::unique_ptr<MCAsmBackend> MAB(
517         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
518 
519     auto FOut = std::make_unique<formatted_raw_ostream>(*Out);
520     Str.reset(TheTarget->createAsmStreamer(
521         Ctx, std::move(FOut), /*asmverbose*/ true,
522         /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
523         Opts.ShowInst));
524   } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
525     Str.reset(createNullStreamer(Ctx));
526   } else {
527     assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
528            "Invalid file type!");
529     if (!FDOS->supportsSeeking()) {
530       BOS = std::make_unique<buffer_ostream>(*FDOS);
531       Out = BOS.get();
532     }
533 
534     std::unique_ptr<MCCodeEmitter> CE(
535         TheTarget->createMCCodeEmitter(*MCII, Ctx));
536     std::unique_ptr<MCAsmBackend> MAB(
537         TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
538     assert(MAB && "Unable to create asm backend!");
539 
540     std::unique_ptr<MCObjectWriter> OW =
541         DwoOS ? MAB->createDwoObjectWriter(*Out, *DwoOS)
542               : MAB->createObjectWriter(*Out);
543 
544     Triple T(Opts.Triple);
545     Str.reset(TheTarget->createMCObjectStreamer(
546         T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI,
547         Opts.RelaxAll, Opts.IncrementalLinkerCompatible,
548         /*DWARFMustBeAtTheEnd*/ true));
549     Str.get()->initSections(Opts.NoExecStack, *STI);
550   }
551 
552   // When -fembed-bitcode is passed to clang_as, a 1-byte marker
553   // is emitted in __LLVM,__asm section if the object file is MachO format.
554   if (Opts.EmbedBitcode && Ctx.getObjectFileType() == MCContext::IsMachO) {
555     MCSection *AsmLabel = Ctx.getMachOSection(
556         "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
557     Str.get()->switchSection(AsmLabel);
558     Str.get()->emitZeros(1);
559   }
560 
561   // Assembly to object compilation should leverage assembly info.
562   Str->setUseAssemblerInfoForParsing(true);
563 
564   bool Failed = false;
565 
566   std::unique_ptr<MCAsmParser> Parser(
567       createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
568 
569   // FIXME: init MCTargetOptions from sanitizer flags here.
570   std::unique_ptr<MCTargetAsmParser> TAP(
571       TheTarget->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
572   if (!TAP)
573     Failed = Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
574 
575   // Set values for symbols, if any.
576   for (auto &S : Opts.SymbolDefs) {
577     auto Pair = StringRef(S).split('=');
578     auto Sym = Pair.first;
579     auto Val = Pair.second;
580     int64_t Value;
581     // We have already error checked this in the driver.
582     Val.getAsInteger(0, Value);
583     Ctx.setSymbolValue(Parser->getStreamer(), Sym, Value);
584   }
585 
586   if (!Failed) {
587     Parser->setTargetParser(*TAP.get());
588     Failed = Parser->Run(Opts.NoInitialTextSection);
589   }
590 
591   return Failed;
592 }
593 
594 static bool ExecuteAssembler(AssemblerInvocation &Opts,
595                              DiagnosticsEngine &Diags) {
596   bool Failed = ExecuteAssemblerImpl(Opts, Diags);
597 
598   // Delete output file if there were errors.
599   if (Failed) {
600     if (Opts.OutputPath != "-")
601       sys::fs::remove(Opts.OutputPath);
602     if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
603       sys::fs::remove(Opts.SplitDwarfOutput);
604   }
605 
606   return Failed;
607 }
608 
609 static void LLVMErrorHandler(void *UserData, const char *Message,
610                              bool GenCrashDiag) {
611   DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
612 
613   Diags.Report(diag::err_fe_error_backend) << Message;
614 
615   // We cannot recover from llvm errors.
616   sys::Process::Exit(1);
617 }
618 
619 int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
620   // Initialize targets and assembly printers/parsers.
621   InitializeAllTargetInfos();
622   InitializeAllTargetMCs();
623   InitializeAllAsmParsers();
624 
625   // Construct our diagnostic client.
626   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
627   TextDiagnosticPrinter *DiagClient
628     = new TextDiagnosticPrinter(errs(), &*DiagOpts);
629   DiagClient->setPrefix("clang -cc1as");
630   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
631   DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
632 
633   // Set an error handler, so that any LLVM backend diagnostics go through our
634   // error handler.
635   ScopedFatalErrorHandler FatalErrorHandler
636     (LLVMErrorHandler, static_cast<void*>(&Diags));
637 
638   // Parse the arguments.
639   AssemblerInvocation Asm;
640   if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
641     return 1;
642 
643   if (Asm.ShowHelp) {
644     getDriverOptTable().printHelp(
645         llvm::outs(), "clang -cc1as [options] file...",
646         "Clang Integrated Assembler", /*ShowHidden=*/false,
647         /*ShowAllAliases=*/false,
648         llvm::opt::Visibility(driver::options::CC1AsOption));
649 
650     return 0;
651   }
652 
653   // Honor -version.
654   //
655   // FIXME: Use a better -version message?
656   if (Asm.ShowVersion) {
657     llvm::cl::PrintVersionMessage();
658     return 0;
659   }
660 
661   // Honor -mllvm.
662   //
663   // FIXME: Remove this, one day.
664   if (!Asm.LLVMArgs.empty()) {
665     unsigned NumArgs = Asm.LLVMArgs.size();
666     auto Args = std::make_unique<const char*[]>(NumArgs + 2);
667     Args[0] = "clang (LLVM option parsing)";
668     for (unsigned i = 0; i != NumArgs; ++i)
669       Args[i + 1] = Asm.LLVMArgs[i].c_str();
670     Args[NumArgs + 1] = nullptr;
671     llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
672   }
673 
674   // Execute the invocation, unless there were parsing errors.
675   bool Failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
676 
677   // If any timers were active but haven't been destroyed yet, print their
678   // results now.
679   TimerGroup::printAll(errs());
680   TimerGroup::clearAll();
681 
682   return !!Failed;
683 }
684