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      1 //===-- llc.cpp - Implement the LLVM Native Code Generator ----------------===//
      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 llc code generator driver. It provides a convenient
     11 // command-line interface for generating native assembly-language code
     12 // or C code, given LLVM bitcode.
     13 //
     14 //===----------------------------------------------------------------------===//
     15 
     16 
     17 #include "llvm/ADT/STLExtras.h"
     18 #include "llvm/ADT/Triple.h"
     19 #include "llvm/Analysis/TargetLibraryInfo.h"
     20 #include "llvm/CodeGen/CommandFlags.h"
     21 #include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
     22 #include "llvm/CodeGen/LinkAllCodegenComponents.h"
     23 #include "llvm/CodeGen/MIRParser/MIRParser.h"
     24 #include "llvm/CodeGen/MachineFunctionPass.h"
     25 #include "llvm/CodeGen/MachineModuleInfo.h"
     26 #include "llvm/CodeGen/TargetPassConfig.h"
     27 #include "llvm/IR/DataLayout.h"
     28 #include "llvm/IR/DiagnosticInfo.h"
     29 #include "llvm/IR/DiagnosticPrinter.h"
     30 #include "llvm/IR/IRPrintingPasses.h"
     31 #include "llvm/IR/LLVMContext.h"
     32 #include "llvm/IR/LegacyPassManager.h"
     33 #include "llvm/IR/Module.h"
     34 #include "llvm/IR/Verifier.h"
     35 #include "llvm/IRReader/IRReader.h"
     36 #include "llvm/MC/SubtargetFeature.h"
     37 #include "llvm/Pass.h"
     38 #include "llvm/Support/CommandLine.h"
     39 #include "llvm/Support/Debug.h"
     40 #include "llvm/Support/FileSystem.h"
     41 #include "llvm/Support/FormattedStream.h"
     42 #include "llvm/Support/Host.h"
     43 #include "llvm/Support/ManagedStatic.h"
     44 #include "llvm/Support/PluginLoader.h"
     45 #include "llvm/Support/PrettyStackTrace.h"
     46 #include "llvm/Support/Signals.h"
     47 #include "llvm/Support/SourceMgr.h"
     48 #include "llvm/Support/TargetRegistry.h"
     49 #include "llvm/Support/TargetSelect.h"
     50 #include "llvm/Support/ToolOutputFile.h"
     51 #include "llvm/Target/TargetMachine.h"
     52 #include "llvm/Target/TargetSubtargetInfo.h"
     53 #include "llvm/Transforms/Utils/Cloning.h"
     54 #include <memory>
     55 using namespace llvm;
     56 
     57 // General options for llc.  Other pass-specific options are specified
     58 // within the corresponding llc passes, and target-specific options
     59 // and back-end code generation options are specified with the target machine.
     60 //
     61 static cl::opt<std::string>
     62 InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
     63 
     64 static cl::opt<std::string>
     65 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
     66 
     67 static cl::opt<unsigned>
     68 TimeCompilations("time-compilations", cl::Hidden, cl::init(1u),
     69                  cl::value_desc("N"),
     70                  cl::desc("Repeat compilation N times for timing"));
     71 
     72 static cl::opt<bool>
     73 NoIntegratedAssembler("no-integrated-as", cl::Hidden,
     74                       cl::desc("Disable integrated assembler"));
     75 
     76 static cl::opt<bool>
     77     PreserveComments("preserve-as-comments", cl::Hidden,
     78                      cl::desc("Preserve Comments in outputted assembly"),
     79                      cl::init(true));
     80 
     81 // Determine optimization level.
     82 static cl::opt<char>
     83 OptLevel("O",
     84          cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
     85                   "(default = '-O2')"),
     86          cl::Prefix,
     87          cl::ZeroOrMore,
     88          cl::init(' '));
     89 
     90 static cl::opt<std::string>
     91 TargetTriple("mtriple", cl::desc("Override target triple for module"));
     92 
     93 static cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
     94                               cl::desc("Do not verify input module"));
     95 
     96 static cl::opt<bool> DisableSimplifyLibCalls("disable-simplify-libcalls",
     97                                              cl::desc("Disable simplify-libcalls"));
     98 
     99 static cl::opt<bool> ShowMCEncoding("show-mc-encoding", cl::Hidden,
    100                                     cl::desc("Show encoding in .s output"));
    101 
    102 static cl::opt<bool> EnableDwarfDirectory(
    103     "enable-dwarf-directory", cl::Hidden,
    104     cl::desc("Use .file directives with an explicit directory."));
    105 
    106 static cl::opt<bool> AsmVerbose("asm-verbose",
    107                                 cl::desc("Add comments to directives."),
    108                                 cl::init(true));
    109 
    110 static cl::opt<bool>
    111     CompileTwice("compile-twice", cl::Hidden,
    112                  cl::desc("Run everything twice, re-using the same pass "
    113                           "manager and verify the result is the same."),
    114                  cl::init(false));
    115 
    116 static cl::opt<bool> DiscardValueNames(
    117     "discard-value-names",
    118     cl::desc("Discard names from Value (other than GlobalValue)."),
    119     cl::init(false), cl::Hidden);
    120 
    121 namespace {
    122 static ManagedStatic<std::vector<std::string>> RunPassNames;
    123 
    124 struct RunPassOption {
    125   void operator=(const std::string &Val) const {
    126     if (Val.empty())
    127       return;
    128     SmallVector<StringRef, 8> PassNames;
    129     StringRef(Val).split(PassNames, ',', -1, false);
    130     for (auto PassName : PassNames)
    131       RunPassNames->push_back(PassName);
    132   }
    133 };
    134 }
    135 
    136 static RunPassOption RunPassOpt;
    137 
    138 static cl::opt<RunPassOption, true, cl::parser<std::string>> RunPass(
    139     "run-pass",
    140     cl::desc("Run compiler only for specified passes (comma separated list)"),
    141     cl::value_desc("pass-name"), cl::ZeroOrMore, cl::location(RunPassOpt));
    142 
    143 static int compileModule(char **, LLVMContext &);
    144 
    145 static std::unique_ptr<tool_output_file>
    146 GetOutputStream(const char *TargetName, Triple::OSType OS,
    147                 const char *ProgName) {
    148   // If we don't yet have an output filename, make one.
    149   if (OutputFilename.empty()) {
    150     if (InputFilename == "-")
    151       OutputFilename = "-";
    152     else {
    153       // If InputFilename ends in .bc or .ll, remove it.
    154       StringRef IFN = InputFilename;
    155       if (IFN.endswith(".bc") || IFN.endswith(".ll"))
    156         OutputFilename = IFN.drop_back(3);
    157       else if (IFN.endswith(".mir"))
    158         OutputFilename = IFN.drop_back(4);
    159       else
    160         OutputFilename = IFN;
    161 
    162       switch (FileType) {
    163       case TargetMachine::CGFT_AssemblyFile:
    164         if (TargetName[0] == 'c') {
    165           if (TargetName[1] == 0)
    166             OutputFilename += ".cbe.c";
    167           else if (TargetName[1] == 'p' && TargetName[2] == 'p')
    168             OutputFilename += ".cpp";
    169           else
    170             OutputFilename += ".s";
    171         } else
    172           OutputFilename += ".s";
    173         break;
    174       case TargetMachine::CGFT_ObjectFile:
    175         if (OS == Triple::Win32)
    176           OutputFilename += ".obj";
    177         else
    178           OutputFilename += ".o";
    179         break;
    180       case TargetMachine::CGFT_Null:
    181         OutputFilename += ".null";
    182         break;
    183       }
    184     }
    185   }
    186 
    187   // Decide if we need "binary" output.
    188   bool Binary = false;
    189   switch (FileType) {
    190   case TargetMachine::CGFT_AssemblyFile:
    191     break;
    192   case TargetMachine::CGFT_ObjectFile:
    193   case TargetMachine::CGFT_Null:
    194     Binary = true;
    195     break;
    196   }
    197 
    198   // Open the file.
    199   std::error_code EC;
    200   sys::fs::OpenFlags OpenFlags = sys::fs::F_None;
    201   if (!Binary)
    202     OpenFlags |= sys::fs::F_Text;
    203   auto FDOut = llvm::make_unique<tool_output_file>(OutputFilename, EC,
    204                                                    OpenFlags);
    205   if (EC) {
    206     errs() << EC.message() << '\n';
    207     return nullptr;
    208   }
    209 
    210   return FDOut;
    211 }
    212 
    213 static void DiagnosticHandler(const DiagnosticInfo &DI, void *Context) {
    214   bool *HasError = static_cast<bool *>(Context);
    215   if (DI.getSeverity() == DS_Error)
    216     *HasError = true;
    217 
    218   DiagnosticPrinterRawOStream DP(errs());
    219   errs() << LLVMContext::getDiagnosticMessagePrefix(DI.getSeverity()) << ": ";
    220   DI.print(DP);
    221   errs() << "\n";
    222 }
    223 
    224 // main - Entry point for the llc compiler.
    225 //
    226 int main(int argc, char **argv) {
    227   sys::PrintStackTraceOnErrorSignal(argv[0]);
    228   PrettyStackTraceProgram X(argc, argv);
    229 
    230   // Enable debug stream buffering.
    231   EnableDebugBuffering = true;
    232 
    233   LLVMContext Context;
    234   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    235 
    236   // Initialize targets first, so that --version shows registered targets.
    237   InitializeAllTargets();
    238   InitializeAllTargetMCs();
    239   InitializeAllAsmPrinters();
    240   InitializeAllAsmParsers();
    241 
    242   // Initialize codegen and IR passes used by llc so that the -print-after,
    243   // -print-before, and -stop-after options work.
    244   PassRegistry *Registry = PassRegistry::getPassRegistry();
    245   initializeCore(*Registry);
    246   initializeCodeGen(*Registry);
    247   initializeLoopStrengthReducePass(*Registry);
    248   initializeLowerIntrinsicsPass(*Registry);
    249   initializeUnreachableBlockElimLegacyPassPass(*Registry);
    250 
    251   // Register the target printer for --version.
    252   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
    253 
    254   cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
    255 
    256   Context.setDiscardValueNames(DiscardValueNames);
    257 
    258   // Set a diagnostic handler that doesn't exit on the first error
    259   bool HasError = false;
    260   Context.setDiagnosticHandler(DiagnosticHandler, &HasError);
    261 
    262   // Compile the module TimeCompilations times to give better compile time
    263   // metrics.
    264   for (unsigned I = TimeCompilations; I; --I)
    265     if (int RetVal = compileModule(argv, Context))
    266       return RetVal;
    267   return 0;
    268 }
    269 
    270 static int compileModule(char **argv, LLVMContext &Context) {
    271   // Load the module to be compiled...
    272   SMDiagnostic Err;
    273   std::unique_ptr<Module> M;
    274   std::unique_ptr<MIRParser> MIR;
    275   Triple TheTriple;
    276 
    277   bool SkipModule = MCPU == "help" ||
    278                     (!MAttrs.empty() && MAttrs.front() == "help");
    279 
    280   // If user just wants to list available options, skip module loading
    281   if (!SkipModule) {
    282     if (StringRef(InputFilename).endswith_lower(".mir")) {
    283       MIR = createMIRParserFromFile(InputFilename, Err, Context);
    284       if (MIR)
    285         M = MIR->parseLLVMModule();
    286     } else
    287       M = parseIRFile(InputFilename, Err, Context);
    288     if (!M) {
    289       Err.print(argv[0], errs());
    290       return 1;
    291     }
    292 
    293     // Verify module immediately to catch problems before doInitialization() is
    294     // called on any passes.
    295     if (!NoVerify && verifyModule(*M, &errs())) {
    296       errs() << argv[0] << ": " << InputFilename
    297              << ": error: input module is broken!\n";
    298       return 1;
    299     }
    300 
    301     // If we are supposed to override the target triple, do so now.
    302     if (!TargetTriple.empty())
    303       M->setTargetTriple(Triple::normalize(TargetTriple));
    304     TheTriple = Triple(M->getTargetTriple());
    305   } else {
    306     TheTriple = Triple(Triple::normalize(TargetTriple));
    307   }
    308 
    309   if (TheTriple.getTriple().empty())
    310     TheTriple.setTriple(sys::getDefaultTargetTriple());
    311 
    312   // Get the target specific parser.
    313   std::string Error;
    314   const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
    315                                                          Error);
    316   if (!TheTarget) {
    317     errs() << argv[0] << ": " << Error;
    318     return 1;
    319   }
    320 
    321   std::string CPUStr = getCPUStr(), FeaturesStr = getFeaturesStr();
    322 
    323   CodeGenOpt::Level OLvl = CodeGenOpt::Default;
    324   switch (OptLevel) {
    325   default:
    326     errs() << argv[0] << ": invalid optimization level.\n";
    327     return 1;
    328   case ' ': break;
    329   case '0': OLvl = CodeGenOpt::None; break;
    330   case '1': OLvl = CodeGenOpt::Less; break;
    331   case '2': OLvl = CodeGenOpt::Default; break;
    332   case '3': OLvl = CodeGenOpt::Aggressive; break;
    333   }
    334 
    335   TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
    336   Options.DisableIntegratedAS = NoIntegratedAssembler;
    337   Options.MCOptions.ShowMCEncoding = ShowMCEncoding;
    338   Options.MCOptions.MCUseDwarfDirectory = EnableDwarfDirectory;
    339   Options.MCOptions.AsmVerbose = AsmVerbose;
    340   Options.MCOptions.PreserveAsmComments = PreserveComments;
    341 
    342   std::unique_ptr<TargetMachine> Target(
    343       TheTarget->createTargetMachine(TheTriple.getTriple(), CPUStr, FeaturesStr,
    344                                      Options, getRelocModel(), CMModel, OLvl));
    345 
    346   assert(Target && "Could not allocate target machine!");
    347 
    348   // If we don't have a module then just exit now. We do this down
    349   // here since the CPU/Feature help is underneath the target machine
    350   // creation.
    351   if (SkipModule)
    352     return 0;
    353 
    354   assert(M && "Should have exited if we didn't have a module!");
    355   if (FloatABIForCalls != FloatABI::Default)
    356     Options.FloatABIType = FloatABIForCalls;
    357 
    358   // Figure out where we are going to send the output.
    359   std::unique_ptr<tool_output_file> Out =
    360       GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]);
    361   if (!Out) return 1;
    362 
    363   // Build up all of the passes that we want to do to the module.
    364   legacy::PassManager PM;
    365 
    366   // Add an appropriate TargetLibraryInfo pass for the module's triple.
    367   TargetLibraryInfoImpl TLII(Triple(M->getTargetTriple()));
    368 
    369   // The -disable-simplify-libcalls flag actually disables all builtin optzns.
    370   if (DisableSimplifyLibCalls)
    371     TLII.disableAllFunctions();
    372   PM.add(new TargetLibraryInfoWrapperPass(TLII));
    373 
    374   // Add the target data from the target machine, if it exists, or the module.
    375   M->setDataLayout(Target->createDataLayout());
    376 
    377   // Override function attributes based on CPUStr, FeaturesStr, and command line
    378   // flags.
    379   setFunctionAttributes(CPUStr, FeaturesStr, *M);
    380 
    381   if (RelaxAll.getNumOccurrences() > 0 &&
    382       FileType != TargetMachine::CGFT_ObjectFile)
    383     errs() << argv[0]
    384              << ": warning: ignoring -mc-relax-all because filetype != obj";
    385 
    386   {
    387     raw_pwrite_stream *OS = &Out->os();
    388 
    389     // Manually do the buffering rather than using buffer_ostream,
    390     // so we can memcmp the contents in CompileTwice mode
    391     SmallVector<char, 0> Buffer;
    392     std::unique_ptr<raw_svector_ostream> BOS;
    393     if ((FileType != TargetMachine::CGFT_AssemblyFile &&
    394          !Out->os().supportsSeeking()) ||
    395         CompileTwice) {
    396       BOS = make_unique<raw_svector_ostream>(Buffer);
    397       OS = BOS.get();
    398     }
    399 
    400     AnalysisID StartBeforeID = nullptr;
    401     AnalysisID StartAfterID = nullptr;
    402     AnalysisID StopAfterID = nullptr;
    403     const PassRegistry *PR = PassRegistry::getPassRegistry();
    404     if (!RunPassNames->empty()) {
    405       if (!StartAfter.empty() || !StopAfter.empty()) {
    406         errs() << argv[0] << ": start-after and/or stop-after passes are "
    407                              "redundant when run-pass is specified.\n";
    408         return 1;
    409       }
    410       if (!MIR) {
    411         errs() << argv[0] << ": run-pass needs a .mir input.\n";
    412         return 1;
    413       }
    414       LLVMTargetMachine &LLVMTM = static_cast<LLVMTargetMachine&>(*Target);
    415       TargetPassConfig *TPC = LLVMTM.createPassConfig(PM);
    416       PM.add(TPC);
    417       LLVMTM.addMachineModuleInfo(PM);
    418       LLVMTM.addMachineFunctionAnalysis(PM, MIR.get());
    419       TPC->printAndVerify("");
    420 
    421       for (std::string &RunPassName : *RunPassNames) {
    422         const PassInfo *PI = PR->getPassInfo(RunPassName);
    423         if (!PI) {
    424           errs() << argv[0] << ": run-pass " << RunPassName << " is not registered.\n";
    425           return 1;
    426         }
    427 
    428         Pass *P;
    429         if (PI->getTargetMachineCtor())
    430           P = PI->getTargetMachineCtor()(Target.get());
    431         else if (PI->getNormalCtor())
    432           P = PI->getNormalCtor()();
    433         else {
    434           errs() << argv[0] << ": cannot create pass: "
    435                  << PI->getPassName() << "\n";
    436           return 1;
    437         }
    438         std::string Banner
    439           = std::string("After ") + std::string(P->getPassName());
    440         PM.add(P);
    441         TPC->printAndVerify(Banner);
    442       }
    443       PM.add(createPrintMIRPass(*OS));
    444     } else {
    445       if (!StartAfter.empty()) {
    446         const PassInfo *PI = PR->getPassInfo(StartAfter);
    447         if (!PI) {
    448           errs() << argv[0] << ": start-after pass is not registered.\n";
    449           return 1;
    450         }
    451         StartAfterID = PI->getTypeInfo();
    452       }
    453       if (!StopAfter.empty()) {
    454         const PassInfo *PI = PR->getPassInfo(StopAfter);
    455         if (!PI) {
    456           errs() << argv[0] << ": stop-after pass is not registered.\n";
    457           return 1;
    458         }
    459         StopAfterID = PI->getTypeInfo();
    460       }
    461 
    462       // Ask the target to add backend passes as necessary.
    463       if (Target->addPassesToEmitFile(PM, *OS, FileType, NoVerify,
    464                                       StartBeforeID, StartAfterID, StopAfterID,
    465                                       MIR.get())) {
    466         errs() << argv[0] << ": target does not support generation of this"
    467                << " file type!\n";
    468         return 1;
    469       }
    470     }
    471 
    472     // Before executing passes, print the final values of the LLVM options.
    473     cl::PrintOptionValues();
    474 
    475     // If requested, run the pass manager over the same module again,
    476     // to catch any bugs due to persistent state in the passes. Note that
    477     // opt has the same functionality, so it may be worth abstracting this out
    478     // in the future.
    479     SmallVector<char, 0> CompileTwiceBuffer;
    480     if (CompileTwice) {
    481       std::unique_ptr<Module> M2(llvm::CloneModule(M.get()));
    482       PM.run(*M2);
    483       CompileTwiceBuffer = Buffer;
    484       Buffer.clear();
    485     }
    486 
    487     PM.run(*M);
    488 
    489     auto HasError = *static_cast<bool *>(Context.getDiagnosticContext());
    490     if (HasError)
    491       return 1;
    492 
    493     // Compare the two outputs and make sure they're the same
    494     if (CompileTwice) {
    495       if (Buffer.size() != CompileTwiceBuffer.size() ||
    496           (memcmp(Buffer.data(), CompileTwiceBuffer.data(), Buffer.size()) !=
    497            0)) {
    498         errs()
    499             << "Running the pass manager twice changed the output.\n"
    500                "Writing the result of the second run to the specified output\n"
    501                "To generate the one-run comparison binary, just run without\n"
    502                "the compile-twice option\n";
    503         Out->os() << Buffer;
    504         Out->keep();
    505         return 1;
    506       }
    507     }
    508 
    509     if (BOS) {
    510       Out->os() << Buffer;
    511     }
    512   }
    513 
    514   // Declare success.
    515   Out->keep();
    516 
    517   return 0;
    518 }
    519