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