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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/IR/LLVMContext.h"
     18 #include "llvm/ADT/Triple.h"
     19 #include "llvm/Assembly/PrintModulePass.h"
     20 #include "llvm/CodeGen/CommandFlags.h"
     21 #include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
     22 #include "llvm/CodeGen/LinkAllCodegenComponents.h"
     23 #include "llvm/IR/DataLayout.h"
     24 #include "llvm/IR/Module.h"
     25 #include "llvm/IRReader/IRReader.h"
     26 #include "llvm/MC/SubtargetFeature.h"
     27 #include "llvm/Pass.h"
     28 #include "llvm/PassManager.h"
     29 #include "llvm/Support/CommandLine.h"
     30 #include "llvm/Support/Debug.h"
     31 #include "llvm/Support/FormattedStream.h"
     32 #include "llvm/Support/Host.h"
     33 #include "llvm/Support/ManagedStatic.h"
     34 #include "llvm/Support/PluginLoader.h"
     35 #include "llvm/Support/PrettyStackTrace.h"
     36 #include "llvm/Support/Signals.h"
     37 #include "llvm/Support/SourceMgr.h"
     38 #include "llvm/Support/TargetRegistry.h"
     39 #include "llvm/Support/TargetSelect.h"
     40 #include "llvm/Support/ToolOutputFile.h"
     41 #include "llvm/Target/TargetLibraryInfo.h"
     42 #include "llvm/Target/TargetMachine.h"
     43 #include <memory>
     44 using namespace llvm;
     45 
     46 // General options for llc.  Other pass-specific options are specified
     47 // within the corresponding llc passes, and target-specific options
     48 // and back-end code generation options are specified with the target machine.
     49 //
     50 static cl::opt<std::string>
     51 InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
     52 
     53 static cl::opt<std::string>
     54 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
     55 
     56 static cl::opt<unsigned>
     57 TimeCompilations("time-compilations", cl::Hidden, cl::init(1u),
     58                  cl::value_desc("N"),
     59                  cl::desc("Repeat compilation N times for timing"));
     60 
     61 // Determine optimization level.
     62 static cl::opt<char>
     63 OptLevel("O",
     64          cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
     65                   "(default = '-O2')"),
     66          cl::Prefix,
     67          cl::ZeroOrMore,
     68          cl::init(' '));
     69 
     70 static cl::opt<std::string>
     71 TargetTriple("mtriple", cl::desc("Override target triple for module"));
     72 
     73 cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
     74                        cl::desc("Do not verify input module"));
     75 
     76 cl::opt<bool>
     77 DisableSimplifyLibCalls("disable-simplify-libcalls",
     78                         cl::desc("Disable simplify-libcalls"),
     79                         cl::init(false));
     80 
     81 static int compileModule(char**, LLVMContext&);
     82 
     83 // GetFileNameRoot - Helper function to get the basename of a filename.
     84 static inline std::string
     85 GetFileNameRoot(const std::string &InputFilename) {
     86   std::string IFN = InputFilename;
     87   std::string outputFilename;
     88   int Len = IFN.length();
     89   if ((Len > 2) &&
     90       IFN[Len-3] == '.' &&
     91       ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
     92        (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
     93     outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
     94   } else {
     95     outputFilename = IFN;
     96   }
     97   return outputFilename;
     98 }
     99 
    100 static tool_output_file *GetOutputStream(const char *TargetName,
    101                                          Triple::OSType OS,
    102                                          const char *ProgName) {
    103   // If we don't yet have an output filename, make one.
    104   if (OutputFilename.empty()) {
    105     if (InputFilename == "-")
    106       OutputFilename = "-";
    107     else {
    108       OutputFilename = GetFileNameRoot(InputFilename);
    109 
    110       switch (FileType) {
    111       case TargetMachine::CGFT_AssemblyFile:
    112         if (TargetName[0] == 'c') {
    113           if (TargetName[1] == 0)
    114             OutputFilename += ".cbe.c";
    115           else if (TargetName[1] == 'p' && TargetName[2] == 'p')
    116             OutputFilename += ".cpp";
    117           else
    118             OutputFilename += ".s";
    119         } else
    120           OutputFilename += ".s";
    121         break;
    122       case TargetMachine::CGFT_ObjectFile:
    123         if (OS == Triple::Win32)
    124           OutputFilename += ".obj";
    125         else
    126           OutputFilename += ".o";
    127         break;
    128       case TargetMachine::CGFT_Null:
    129         OutputFilename += ".null";
    130         break;
    131       }
    132     }
    133   }
    134 
    135   // Decide if we need "binary" output.
    136   bool Binary = false;
    137   switch (FileType) {
    138   case TargetMachine::CGFT_AssemblyFile:
    139     break;
    140   case TargetMachine::CGFT_ObjectFile:
    141   case TargetMachine::CGFT_Null:
    142     Binary = true;
    143     break;
    144   }
    145 
    146   // Open the file.
    147   std::string error;
    148   sys::fs::OpenFlags OpenFlags = sys::fs::F_None;
    149   if (Binary)
    150     OpenFlags |= sys::fs::F_Binary;
    151   tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
    152                                                  OpenFlags);
    153   if (!error.empty()) {
    154     errs() << error << '\n';
    155     delete FDOut;
    156     return 0;
    157   }
    158 
    159   return FDOut;
    160 }
    161 
    162 // main - Entry point for the llc compiler.
    163 //
    164 int main(int argc, char **argv) {
    165   sys::PrintStackTraceOnErrorSignal();
    166   PrettyStackTraceProgram X(argc, argv);
    167 
    168   // Enable debug stream buffering.
    169   EnableDebugBuffering = true;
    170 
    171   LLVMContext &Context = getGlobalContext();
    172   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    173 
    174   // Initialize targets first, so that --version shows registered targets.
    175   InitializeAllTargets();
    176   InitializeAllTargetMCs();
    177   InitializeAllAsmPrinters();
    178   InitializeAllAsmParsers();
    179 
    180   // Initialize codegen and IR passes used by llc so that the -print-after,
    181   // -print-before, and -stop-after options work.
    182   PassRegistry *Registry = PassRegistry::getPassRegistry();
    183   initializeCore(*Registry);
    184   initializeCodeGen(*Registry);
    185   initializeLoopStrengthReducePass(*Registry);
    186   initializeLowerIntrinsicsPass(*Registry);
    187   initializeUnreachableBlockElimPass(*Registry);
    188 
    189   // Register the target printer for --version.
    190   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
    191 
    192   cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
    193 
    194   // Compile the module TimeCompilations times to give better compile time
    195   // metrics.
    196   for (unsigned I = TimeCompilations; I; --I)
    197     if (int RetVal = compileModule(argv, Context))
    198       return RetVal;
    199   return 0;
    200 }
    201 
    202 static int compileModule(char **argv, LLVMContext &Context) {
    203   // Load the module to be compiled...
    204   SMDiagnostic Err;
    205   OwningPtr<Module> M;
    206   Module *mod = 0;
    207   Triple TheTriple;
    208 
    209   bool SkipModule = MCPU == "help" ||
    210                     (!MAttrs.empty() && MAttrs.front() == "help");
    211 
    212   // If user just wants to list available options, skip module loading
    213   if (!SkipModule) {
    214     M.reset(ParseIRFile(InputFilename, Err, Context));
    215     mod = M.get();
    216     if (mod == 0) {
    217       Err.print(argv[0], errs());
    218       return 1;
    219     }
    220 
    221     // If we are supposed to override the target triple, do so now.
    222     if (!TargetTriple.empty())
    223       mod->setTargetTriple(Triple::normalize(TargetTriple));
    224     TheTriple = Triple(mod->getTargetTriple());
    225   } else {
    226     TheTriple = Triple(Triple::normalize(TargetTriple));
    227   }
    228 
    229   if (TheTriple.getTriple().empty())
    230     TheTriple.setTriple(sys::getDefaultTargetTriple());
    231 
    232   // Get the target specific parser.
    233   std::string Error;
    234   const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
    235                                                          Error);
    236   if (!TheTarget) {
    237     errs() << argv[0] << ": " << Error;
    238     return 1;
    239   }
    240 
    241   // Package up features to be passed to target/subtarget
    242   std::string FeaturesStr;
    243   if (MAttrs.size()) {
    244     SubtargetFeatures Features;
    245     for (unsigned i = 0; i != MAttrs.size(); ++i)
    246       Features.AddFeature(MAttrs[i]);
    247     FeaturesStr = Features.getString();
    248   }
    249 
    250   CodeGenOpt::Level OLvl = CodeGenOpt::Default;
    251   switch (OptLevel) {
    252   default:
    253     errs() << argv[0] << ": invalid optimization level.\n";
    254     return 1;
    255   case ' ': break;
    256   case '0': OLvl = CodeGenOpt::None; break;
    257   case '1': OLvl = CodeGenOpt::Less; break;
    258   case '2': OLvl = CodeGenOpt::Default; break;
    259   case '3': OLvl = CodeGenOpt::Aggressive; break;
    260   }
    261 
    262   TargetOptions Options;
    263   Options.LessPreciseFPMADOption = EnableFPMAD;
    264   Options.NoFramePointerElim = DisableFPElim;
    265   Options.AllowFPOpFusion = FuseFPOps;
    266   Options.UnsafeFPMath = EnableUnsafeFPMath;
    267   Options.NoInfsFPMath = EnableNoInfsFPMath;
    268   Options.NoNaNsFPMath = EnableNoNaNsFPMath;
    269   Options.HonorSignDependentRoundingFPMathOption =
    270       EnableHonorSignDependentRoundingFPMath;
    271   Options.UseSoftFloat = GenerateSoftFloatCalls;
    272   if (FloatABIForCalls != FloatABI::Default)
    273     Options.FloatABIType = FloatABIForCalls;
    274   Options.NoZerosInBSS = DontPlaceZerosInBSS;
    275   Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
    276   Options.DisableTailCalls = DisableTailCalls;
    277   Options.StackAlignmentOverride = OverrideStackAlignment;
    278   Options.TrapFuncName = TrapFuncName;
    279   Options.PositionIndependentExecutable = EnablePIE;
    280   Options.EnableSegmentedStacks = SegmentedStacks;
    281   Options.UseInitArray = UseInitArray;
    282 
    283   OwningPtr<TargetMachine>
    284     target(TheTarget->createTargetMachine(TheTriple.getTriple(),
    285                                           MCPU, FeaturesStr, Options,
    286                                           RelocModel, CMModel, OLvl));
    287   assert(target.get() && "Could not allocate target machine!");
    288   assert(mod && "Should have exited after outputting help!");
    289   TargetMachine &Target = *target.get();
    290 
    291   if (DisableDotLoc)
    292     Target.setMCUseLoc(false);
    293 
    294   if (DisableCFI)
    295     Target.setMCUseCFI(false);
    296 
    297   if (EnableDwarfDirectory)
    298     Target.setMCUseDwarfDirectory(true);
    299 
    300   if (GenerateSoftFloatCalls)
    301     FloatABIForCalls = FloatABI::Soft;
    302 
    303   // Disable .loc support for older OS X versions.
    304   if (TheTriple.isMacOSX() &&
    305       TheTriple.isMacOSXVersionLT(10, 6))
    306     Target.setMCUseLoc(false);
    307 
    308   // Figure out where we are going to send the output.
    309   OwningPtr<tool_output_file> Out
    310     (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
    311   if (!Out) return 1;
    312 
    313   // Build up all of the passes that we want to do to the module.
    314   PassManager PM;
    315 
    316   // Add an appropriate TargetLibraryInfo pass for the module's triple.
    317   TargetLibraryInfo *TLI = new TargetLibraryInfo(TheTriple);
    318   if (DisableSimplifyLibCalls)
    319     TLI->disableAllFunctions();
    320   PM.add(TLI);
    321 
    322   // Add intenal analysis passes from the target machine.
    323   Target.addAnalysisPasses(PM);
    324 
    325   // Add the target data from the target machine, if it exists, or the module.
    326   if (const DataLayout *TD = Target.getDataLayout())
    327     PM.add(new DataLayout(*TD));
    328   else
    329     PM.add(new DataLayout(mod));
    330 
    331   // Override default to generate verbose assembly.
    332   Target.setAsmVerbosityDefault(true);
    333 
    334   if (RelaxAll) {
    335     if (FileType != TargetMachine::CGFT_ObjectFile)
    336       errs() << argv[0]
    337              << ": warning: ignoring -mc-relax-all because filetype != obj";
    338     else
    339       Target.setMCRelaxAll(true);
    340   }
    341 
    342   {
    343     formatted_raw_ostream FOS(Out->os());
    344 
    345     AnalysisID StartAfterID = 0;
    346     AnalysisID StopAfterID = 0;
    347     const PassRegistry *PR = PassRegistry::getPassRegistry();
    348     if (!StartAfter.empty()) {
    349       const PassInfo *PI = PR->getPassInfo(StartAfter);
    350       if (!PI) {
    351         errs() << argv[0] << ": start-after pass is not registered.\n";
    352         return 1;
    353       }
    354       StartAfterID = PI->getTypeInfo();
    355     }
    356     if (!StopAfter.empty()) {
    357       const PassInfo *PI = PR->getPassInfo(StopAfter);
    358       if (!PI) {
    359         errs() << argv[0] << ": stop-after pass is not registered.\n";
    360         return 1;
    361       }
    362       StopAfterID = PI->getTypeInfo();
    363     }
    364 
    365     // Ask the target to add backend passes as necessary.
    366     if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify,
    367                                    StartAfterID, StopAfterID)) {
    368       errs() << argv[0] << ": target does not support generation of this"
    369              << " file type!\n";
    370       return 1;
    371     }
    372 
    373     // Before executing passes, print the final values of the LLVM options.
    374     cl::PrintOptionValues();
    375 
    376     PM.run(*mod);
    377   }
    378 
    379   // Declare success.
    380   Out->keep();
    381 
    382   return 0;
    383 }
    384