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