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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 #include "llvm/IR/LLVMContext.h"
     17 #include "llvm/ADT/Triple.h"
     18 #include "llvm/Assembly/PrintModulePass.h"
     19 #include "llvm/CodeGen/CommandFlags.h"
     20 #include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
     21 #include "llvm/CodeGen/LinkAllCodegenComponents.h"
     22 #include "llvm/IR/DataLayout.h"
     23 #include "llvm/IR/Module.h"
     24 #include "llvm/MC/SubtargetFeature.h"
     25 #include "llvm/Pass.h"
     26 #include "llvm/PassManager.h"
     27 #include "llvm/Support/CommandLine.h"
     28 #include "llvm/Support/Debug.h"
     29 #include "llvm/Support/FormattedStream.h"
     30 #include "llvm/Support/Host.h"
     31 #include "llvm/Support/IRReader.h"
     32 #include "llvm/Support/ManagedStatic.h"
     33 #include "llvm/Support/PluginLoader.h"
     34 #include "llvm/Support/PrettyStackTrace.h"
     35 #include "llvm/Support/Signals.h"
     36 #include "llvm/Support/TargetRegistry.h"
     37 #include "llvm/Support/TargetSelect.h"
     38 #include "llvm/Support/ToolOutputFile.h"
     39 #include "llvm/Target/TargetLibraryInfo.h"
     40 #include "llvm/Target/TargetMachine.h"
     41 #include <memory>
     42 using namespace llvm;
     43 
     44 // General options for llc.  Other pass-specific options are specified
     45 // within the corresponding llc passes, and target-specific options
     46 // and back-end code generation options are specified with the target machine.
     47 //
     48 static cl::opt<std::string>
     49 InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
     50 
     51 static cl::opt<std::string>
     52 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
     53 
     54 static cl::opt<unsigned>
     55 TimeCompilations("time-compilations", cl::Hidden, cl::init(1u),
     56                  cl::value_desc("N"),
     57                  cl::desc("Repeat compilation N times for timing"));
     58 
     59 // Determine optimization level.
     60 static cl::opt<char>
     61 OptLevel("O",
     62          cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
     63                   "(default = '-O2')"),
     64          cl::Prefix,
     65          cl::ZeroOrMore,
     66          cl::init(' '));
     67 
     68 static cl::opt<std::string>
     69 TargetTriple("mtriple", cl::desc("Override target triple for module"));
     70 
     71 cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
     72                        cl::desc("Do not verify input module"));
     73 
     74 cl::opt<bool>
     75 DisableSimplifyLibCalls("disable-simplify-libcalls",
     76                         cl::desc("Disable simplify-libcalls"),
     77                         cl::init(false));
     78 
     79 static int compileModule(char**, LLVMContext&);
     80 
     81 // GetFileNameRoot - Helper function to get the basename of a filename.
     82 static inline std::string
     83 GetFileNameRoot(const std::string &InputFilename) {
     84   std::string IFN = InputFilename;
     85   std::string outputFilename;
     86   int Len = IFN.length();
     87   if ((Len > 2) &&
     88       IFN[Len-3] == '.' &&
     89       ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
     90        (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
     91     outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
     92   } else {
     93     outputFilename = IFN;
     94   }
     95   return outputFilename;
     96 }
     97 
     98 static tool_output_file *GetOutputStream(const char *TargetName,
     99                                          Triple::OSType OS,
    100                                          const char *ProgName) {
    101   // If we don't yet have an output filename, make one.
    102   if (OutputFilename.empty()) {
    103     if (InputFilename == "-")
    104       OutputFilename = "-";
    105     else {
    106       OutputFilename = GetFileNameRoot(InputFilename);
    107 
    108       switch (FileType) {
    109       case TargetMachine::CGFT_AssemblyFile:
    110         if (TargetName[0] == 'c') {
    111           if (TargetName[1] == 0)
    112             OutputFilename += ".cbe.c";
    113           else if (TargetName[1] == 'p' && TargetName[2] == 'p')
    114             OutputFilename += ".cpp";
    115           else
    116             OutputFilename += ".s";
    117         } else
    118           OutputFilename += ".s";
    119         break;
    120       case TargetMachine::CGFT_ObjectFile:
    121         if (OS == Triple::Win32)
    122           OutputFilename += ".obj";
    123         else
    124           OutputFilename += ".o";
    125         break;
    126       case TargetMachine::CGFT_Null:
    127         OutputFilename += ".null";
    128         break;
    129       }
    130     }
    131   }
    132 
    133   // Decide if we need "binary" output.
    134   bool Binary = false;
    135   switch (FileType) {
    136   case TargetMachine::CGFT_AssemblyFile:
    137     break;
    138   case TargetMachine::CGFT_ObjectFile:
    139   case TargetMachine::CGFT_Null:
    140     Binary = true;
    141     break;
    142   }
    143 
    144   // Open the file.
    145   std::string error;
    146   unsigned OpenFlags = 0;
    147   if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
    148   tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
    149                                                  OpenFlags);
    150   if (!error.empty()) {
    151     errs() << error << '\n';
    152     delete FDOut;
    153     return 0;
    154   }
    155 
    156   return FDOut;
    157 }
    158 
    159 // main - Entry point for the llc compiler.
    160 //
    161 int main(int argc, char **argv) {
    162   sys::PrintStackTraceOnErrorSignal();
    163   PrettyStackTraceProgram X(argc, argv);
    164 
    165   // Enable debug stream buffering.
    166   EnableDebugBuffering = true;
    167 
    168   LLVMContext &Context = getGlobalContext();
    169   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    170 
    171   // Initialize targets first, so that --version shows registered targets.
    172   InitializeAllTargets();
    173   InitializeAllTargetMCs();
    174   InitializeAllAsmPrinters();
    175   InitializeAllAsmParsers();
    176 
    177   // Initialize codegen and IR passes used by llc so that the -print-after,
    178   // -print-before, and -stop-after options work.
    179   PassRegistry *Registry = PassRegistry::getPassRegistry();
    180   initializeCore(*Registry);
    181   initializeCodeGen(*Registry);
    182   initializeLoopStrengthReducePass(*Registry);
    183   initializeLowerIntrinsicsPass(*Registry);
    184   initializeUnreachableBlockElimPass(*Registry);
    185 
    186   // Register the target printer for --version.
    187   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
    188 
    189   cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
    190 
    191   // Compile the module TimeCompilations times to give better compile time
    192   // metrics.
    193   for (unsigned I = TimeCompilations; I; --I)
    194     if (int RetVal = compileModule(argv, Context))
    195       return RetVal;
    196   return 0;
    197 }
    198 
    199 static int compileModule(char **argv, LLVMContext &Context) {
    200   // Load the module to be compiled...
    201   SMDiagnostic Err;
    202   std::auto_ptr<Module> M;
    203   Module *mod = 0;
    204   Triple TheTriple;
    205 
    206   bool SkipModule = MCPU == "help" ||
    207                     (!MAttrs.empty() && MAttrs.front() == "help");
    208 
    209   // If user just wants to list available options, skip module loading
    210   if (!SkipModule) {
    211     M.reset(ParseIRFile(InputFilename, Err, Context));
    212     mod = M.get();
    213     if (mod == 0) {
    214       Err.print(argv[0], errs());
    215       return 1;
    216     }
    217 
    218     // If we are supposed to override the target triple, do so now.
    219     if (!TargetTriple.empty())
    220       mod->setTargetTriple(Triple::normalize(TargetTriple));
    221     TheTriple = Triple(mod->getTargetTriple());
    222   } else {
    223     TheTriple = Triple(Triple::normalize(TargetTriple));
    224   }
    225 
    226   if (TheTriple.getTriple().empty())
    227     TheTriple.setTriple(sys::getDefaultTargetTriple());
    228 
    229   // Get the target specific parser.
    230   std::string Error;
    231   const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
    232                                                          Error);
    233   if (!TheTarget) {
    234     errs() << argv[0] << ": " << Error;
    235     return 1;
    236   }
    237 
    238   // Package up features to be passed to target/subtarget
    239   std::string FeaturesStr;
    240   if (MAttrs.size()) {
    241     SubtargetFeatures Features;
    242     for (unsigned i = 0; i != MAttrs.size(); ++i)
    243       Features.AddFeature(MAttrs[i]);
    244     FeaturesStr = Features.getString();
    245   }
    246 
    247   CodeGenOpt::Level OLvl = CodeGenOpt::Default;
    248   switch (OptLevel) {
    249   default:
    250     errs() << argv[0] << ": invalid optimization level.\n";
    251     return 1;
    252   case ' ': break;
    253   case '0': OLvl = CodeGenOpt::None; break;
    254   case '1': OLvl = CodeGenOpt::Less; break;
    255   case '2': OLvl = CodeGenOpt::Default; break;
    256   case '3': OLvl = CodeGenOpt::Aggressive; break;
    257   }
    258 
    259   TargetOptions Options;
    260   Options.LessPreciseFPMADOption = EnableFPMAD;
    261   Options.NoFramePointerElim = DisableFPElim;
    262   Options.NoFramePointerElimNonLeaf = DisableFPElimNonLeaf;
    263   Options.AllowFPOpFusion = FuseFPOps;
    264   Options.UnsafeFPMath = EnableUnsafeFPMath;
    265   Options.NoInfsFPMath = EnableNoInfsFPMath;
    266   Options.NoNaNsFPMath = EnableNoNaNsFPMath;
    267   Options.HonorSignDependentRoundingFPMathOption =
    268       EnableHonorSignDependentRoundingFPMath;
    269   Options.UseSoftFloat = GenerateSoftFloatCalls;
    270   if (FloatABIForCalls != FloatABI::Default)
    271     Options.FloatABIType = FloatABIForCalls;
    272   Options.NoZerosInBSS = DontPlaceZerosInBSS;
    273   Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
    274   Options.DisableTailCalls = DisableTailCalls;
    275   Options.StackAlignmentOverride = OverrideStackAlignment;
    276   Options.RealignStack = EnableRealignStack;
    277   Options.TrapFuncName = TrapFuncName;
    278   Options.PositionIndependentExecutable = EnablePIE;
    279   Options.EnableSegmentedStacks = SegmentedStacks;
    280   Options.UseInitArray = UseInitArray;
    281   Options.SSPBufferSize = SSPBufferSize;
    282 
    283   std::auto_ptr<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