1 //===-- llvm-lto: a simple command-line program to link modules with LTO --===// 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 program takes in a list of bitcode files, links them, performs link-time 11 // optimization, and outputs an object file. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/ADT/StringSet.h" 16 #include "llvm/Bitcode/ReaderWriter.h" 17 #include "llvm/CodeGen/CommandFlags.h" 18 #include "llvm/IR/DiagnosticPrinter.h" 19 #include "llvm/IR/LLVMContext.h" 20 #include "llvm/LTO/LTOCodeGenerator.h" 21 #include "llvm/LTO/LTOModule.h" 22 #include "llvm/Object/FunctionIndexObjectFile.h" 23 #include "llvm/Support/CommandLine.h" 24 #include "llvm/Support/FileSystem.h" 25 #include "llvm/Support/ManagedStatic.h" 26 #include "llvm/Support/PrettyStackTrace.h" 27 #include "llvm/Support/Signals.h" 28 #include "llvm/Support/TargetSelect.h" 29 #include "llvm/Support/ToolOutputFile.h" 30 #include "llvm/Support/raw_ostream.h" 31 #include <list> 32 33 using namespace llvm; 34 35 static cl::opt<char> 36 OptLevel("O", 37 cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] " 38 "(default = '-O2')"), 39 cl::Prefix, 40 cl::ZeroOrMore, 41 cl::init('2')); 42 43 static cl::opt<bool> DisableVerify( 44 "disable-verify", cl::init(false), 45 cl::desc("Do not run the verifier during the optimization pipeline")); 46 47 static cl::opt<bool> 48 DisableInline("disable-inlining", cl::init(false), 49 cl::desc("Do not run the inliner pass")); 50 51 static cl::opt<bool> 52 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false), 53 cl::desc("Do not run the GVN load PRE pass")); 54 55 static cl::opt<bool> 56 DisableLTOVectorization("disable-lto-vectorization", cl::init(false), 57 cl::desc("Do not run loop or slp vectorization during LTO")); 58 59 static cl::opt<bool> 60 UseDiagnosticHandler("use-diagnostic-handler", cl::init(false), 61 cl::desc("Use a diagnostic handler to test the handler interface")); 62 63 static cl::opt<bool> 64 ThinLTO("thinlto", cl::init(false), 65 cl::desc("Only write combined global index for ThinLTO backends")); 66 67 static cl::opt<bool> 68 SaveModuleFile("save-merged-module", cl::init(false), 69 cl::desc("Write merged LTO module to file before CodeGen")); 70 71 static cl::list<std::string> 72 InputFilenames(cl::Positional, cl::OneOrMore, 73 cl::desc("<input bitcode files>")); 74 75 static cl::opt<std::string> 76 OutputFilename("o", cl::init(""), 77 cl::desc("Override output filename"), 78 cl::value_desc("filename")); 79 80 static cl::list<std::string> 81 ExportedSymbols("exported-symbol", 82 cl::desc("Symbol to export from the resulting object file"), 83 cl::ZeroOrMore); 84 85 static cl::list<std::string> 86 DSOSymbols("dso-symbol", 87 cl::desc("Symbol to put in the symtab in the resulting dso"), 88 cl::ZeroOrMore); 89 90 static cl::opt<bool> ListSymbolsOnly( 91 "list-symbols-only", cl::init(false), 92 cl::desc("Instead of running LTO, list the symbols in each IR file")); 93 94 static cl::opt<bool> SetMergedModule( 95 "set-merged-module", cl::init(false), 96 cl::desc("Use the first input module as the merged module")); 97 98 static cl::opt<unsigned> Parallelism("j", cl::Prefix, cl::init(1), 99 cl::desc("Number of backend threads")); 100 101 namespace { 102 struct ModuleInfo { 103 std::vector<bool> CanBeHidden; 104 }; 105 } 106 107 static void handleDiagnostics(lto_codegen_diagnostic_severity_t Severity, 108 const char *Msg, void *) { 109 errs() << "llvm-lto: "; 110 switch (Severity) { 111 case LTO_DS_NOTE: 112 errs() << "note: "; 113 break; 114 case LTO_DS_REMARK: 115 errs() << "remark: "; 116 break; 117 case LTO_DS_ERROR: 118 errs() << "error: "; 119 break; 120 case LTO_DS_WARNING: 121 errs() << "warning: "; 122 break; 123 } 124 errs() << Msg << "\n"; 125 } 126 127 static std::string CurrentActivity; 128 static void diagnosticHandler(const DiagnosticInfo &DI) { 129 raw_ostream &OS = errs(); 130 OS << "llvm-lto: "; 131 switch (DI.getSeverity()) { 132 case DS_Error: 133 OS << "error"; 134 break; 135 case DS_Warning: 136 OS << "warning"; 137 break; 138 case DS_Remark: 139 OS << "remark"; 140 break; 141 case DS_Note: 142 OS << "note"; 143 break; 144 } 145 if (!CurrentActivity.empty()) 146 OS << ' ' << CurrentActivity; 147 OS << ": "; 148 149 DiagnosticPrinterRawOStream DP(OS); 150 DI.print(DP); 151 OS << '\n'; 152 153 if (DI.getSeverity() == DS_Error) 154 exit(1); 155 } 156 157 static void diagnosticHandlerWithContenxt(const DiagnosticInfo &DI, 158 void *Context) { 159 diagnosticHandler(DI); 160 } 161 162 static void error(const Twine &Msg) { 163 errs() << "llvm-lto: " << Msg << '\n'; 164 exit(1); 165 } 166 167 static void error(std::error_code EC, const Twine &Prefix) { 168 if (EC) 169 error(Prefix + ": " + EC.message()); 170 } 171 172 template <typename T> 173 static void error(const ErrorOr<T> &V, const Twine &Prefix) { 174 error(V.getError(), Prefix); 175 } 176 177 static std::unique_ptr<LTOModule> 178 getLocalLTOModule(StringRef Path, std::unique_ptr<MemoryBuffer> &Buffer, 179 const TargetOptions &Options) { 180 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr = 181 MemoryBuffer::getFile(Path); 182 error(BufferOrErr, "error loading file '" + Path + "'"); 183 Buffer = std::move(BufferOrErr.get()); 184 CurrentActivity = ("loading file '" + Path + "'").str(); 185 ErrorOr<std::unique_ptr<LTOModule>> Ret = LTOModule::createInLocalContext( 186 Buffer->getBufferStart(), Buffer->getBufferSize(), Options, Path); 187 CurrentActivity = ""; 188 return std::move(*Ret); 189 } 190 191 /// \brief List symbols in each IR file. 192 /// 193 /// The main point here is to provide lit-testable coverage for the LTOModule 194 /// functionality that's exposed by the C API to list symbols. Moreover, this 195 /// provides testing coverage for modules that have been created in their own 196 /// contexts. 197 static void listSymbols(const TargetOptions &Options) { 198 for (auto &Filename : InputFilenames) { 199 std::unique_ptr<MemoryBuffer> Buffer; 200 std::unique_ptr<LTOModule> Module = 201 getLocalLTOModule(Filename, Buffer, Options); 202 203 // List the symbols. 204 outs() << Filename << ":\n"; 205 for (int I = 0, E = Module->getSymbolCount(); I != E; ++I) 206 outs() << Module->getSymbolName(I) << "\n"; 207 } 208 } 209 210 /// Create a combined index file from the input IR files and write it. 211 /// 212 /// This is meant to enable testing of ThinLTO combined index generation, 213 /// currently available via the gold plugin via -thinlto. 214 static void createCombinedFunctionIndex() { 215 FunctionInfoIndex CombinedIndex; 216 uint64_t NextModuleId = 0; 217 for (auto &Filename : InputFilenames) { 218 CurrentActivity = "loading file '" + Filename + "'"; 219 ErrorOr<std::unique_ptr<FunctionInfoIndex>> IndexOrErr = 220 llvm::getFunctionIndexForFile(Filename, diagnosticHandler); 221 std::unique_ptr<FunctionInfoIndex> Index = std::move(IndexOrErr.get()); 222 CurrentActivity = ""; 223 // Skip files without a function summary. 224 if (!Index) 225 continue; 226 CombinedIndex.mergeFrom(std::move(Index), ++NextModuleId); 227 } 228 std::error_code EC; 229 assert(!OutputFilename.empty()); 230 raw_fd_ostream OS(OutputFilename + ".thinlto.bc", EC, 231 sys::fs::OpenFlags::F_None); 232 error(EC, "error opening the file '" + OutputFilename + ".thinlto.bc'"); 233 WriteFunctionSummaryToFile(CombinedIndex, OS); 234 OS.close(); 235 } 236 237 int main(int argc, char **argv) { 238 // Print a stack trace if we signal out. 239 sys::PrintStackTraceOnErrorSignal(); 240 PrettyStackTraceProgram X(argc, argv); 241 242 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit. 243 cl::ParseCommandLineOptions(argc, argv, "llvm LTO linker\n"); 244 245 if (OptLevel < '0' || OptLevel > '3') 246 error("optimization level must be between 0 and 3"); 247 248 // Initialize the configured targets. 249 InitializeAllTargets(); 250 InitializeAllTargetMCs(); 251 InitializeAllAsmPrinters(); 252 InitializeAllAsmParsers(); 253 254 // set up the TargetOptions for the machine 255 TargetOptions Options = InitTargetOptionsFromCodeGenFlags(); 256 257 if (ListSymbolsOnly) { 258 listSymbols(Options); 259 return 0; 260 } 261 262 if (ThinLTO) { 263 createCombinedFunctionIndex(); 264 return 0; 265 } 266 267 unsigned BaseArg = 0; 268 269 LLVMContext Context; 270 Context.setDiagnosticHandler(diagnosticHandlerWithContenxt, nullptr, true); 271 272 LTOCodeGenerator CodeGen(Context); 273 274 if (UseDiagnosticHandler) 275 CodeGen.setDiagnosticHandler(handleDiagnostics, nullptr); 276 277 CodeGen.setCodePICModel(RelocModel); 278 279 CodeGen.setDebugInfo(LTO_DEBUG_MODEL_DWARF); 280 CodeGen.setTargetOptions(Options); 281 282 llvm::StringSet<llvm::MallocAllocator> DSOSymbolsSet; 283 for (unsigned i = 0; i < DSOSymbols.size(); ++i) 284 DSOSymbolsSet.insert(DSOSymbols[i]); 285 286 std::vector<std::string> KeptDSOSyms; 287 288 for (unsigned i = BaseArg; i < InputFilenames.size(); ++i) { 289 CurrentActivity = "loading file '" + InputFilenames[i] + "'"; 290 ErrorOr<std::unique_ptr<LTOModule>> ModuleOrErr = 291 LTOModule::createFromFile(Context, InputFilenames[i].c_str(), Options); 292 std::unique_ptr<LTOModule> &Module = *ModuleOrErr; 293 CurrentActivity = ""; 294 295 unsigned NumSyms = Module->getSymbolCount(); 296 for (unsigned I = 0; I < NumSyms; ++I) { 297 StringRef Name = Module->getSymbolName(I); 298 if (!DSOSymbolsSet.count(Name)) 299 continue; 300 lto_symbol_attributes Attrs = Module->getSymbolAttributes(I); 301 unsigned Scope = Attrs & LTO_SYMBOL_SCOPE_MASK; 302 if (Scope != LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN) 303 KeptDSOSyms.push_back(Name); 304 } 305 306 // We use the first input module as the destination module when 307 // SetMergedModule is true. 308 if (SetMergedModule && i == BaseArg) { 309 // Transfer ownership to the code generator. 310 CodeGen.setModule(std::move(Module)); 311 } else if (!CodeGen.addModule(Module.get())) { 312 // Print a message here so that we know addModule() did not abort. 313 errs() << argv[0] << ": error adding file '" << InputFilenames[i] << "'\n"; 314 return 1; 315 } 316 } 317 318 // Add all the exported symbols to the table of symbols to preserve. 319 for (unsigned i = 0; i < ExportedSymbols.size(); ++i) 320 CodeGen.addMustPreserveSymbol(ExportedSymbols[i].c_str()); 321 322 // Add all the dso symbols to the table of symbols to expose. 323 for (unsigned i = 0; i < KeptDSOSyms.size(); ++i) 324 CodeGen.addMustPreserveSymbol(KeptDSOSyms[i].c_str()); 325 326 // Set cpu and attrs strings for the default target/subtarget. 327 CodeGen.setCpu(MCPU.c_str()); 328 329 CodeGen.setOptLevel(OptLevel - '0'); 330 331 std::string attrs; 332 for (unsigned i = 0; i < MAttrs.size(); ++i) { 333 if (i > 0) 334 attrs.append(","); 335 attrs.append(MAttrs[i]); 336 } 337 338 if (!attrs.empty()) 339 CodeGen.setAttr(attrs.c_str()); 340 341 if (FileType.getNumOccurrences()) 342 CodeGen.setFileType(FileType); 343 344 if (!OutputFilename.empty()) { 345 if (!CodeGen.optimize(DisableVerify, DisableInline, DisableGVNLoadPRE, 346 DisableLTOVectorization)) { 347 // Diagnostic messages should have been printed by the handler. 348 errs() << argv[0] << ": error optimizing the code\n"; 349 return 1; 350 } 351 352 if (SaveModuleFile) { 353 std::string ModuleFilename = OutputFilename; 354 ModuleFilename += ".merged.bc"; 355 std::string ErrMsg; 356 357 if (!CodeGen.writeMergedModules(ModuleFilename.c_str())) { 358 errs() << argv[0] << ": writing merged module failed.\n"; 359 return 1; 360 } 361 } 362 363 std::list<tool_output_file> OSs; 364 std::vector<raw_pwrite_stream *> OSPtrs; 365 for (unsigned I = 0; I != Parallelism; ++I) { 366 std::string PartFilename = OutputFilename; 367 if (Parallelism != 1) 368 PartFilename += "." + utostr(I); 369 std::error_code EC; 370 OSs.emplace_back(PartFilename, EC, sys::fs::F_None); 371 if (EC) { 372 errs() << argv[0] << ": error opening the file '" << PartFilename 373 << "': " << EC.message() << "\n"; 374 return 1; 375 } 376 OSPtrs.push_back(&OSs.back().os()); 377 } 378 379 if (!CodeGen.compileOptimized(OSPtrs)) { 380 // Diagnostic messages should have been printed by the handler. 381 errs() << argv[0] << ": error compiling the code\n"; 382 return 1; 383 } 384 385 for (tool_output_file &OS : OSs) 386 OS.keep(); 387 } else { 388 if (Parallelism != 1) { 389 errs() << argv[0] << ": -j must be specified together with -o\n"; 390 return 1; 391 } 392 393 if (SaveModuleFile) { 394 errs() << argv[0] << ": -save-merged-module must be specified with -o\n"; 395 return 1; 396 } 397 398 const char *OutputName = nullptr; 399 if (!CodeGen.compile_to_file(&OutputName, DisableVerify, DisableInline, 400 DisableGVNLoadPRE, DisableLTOVectorization)) { 401 // Diagnostic messages should have been printed by the handler. 402 errs() << argv[0] << ": error compiling the code\n"; 403 return 1; 404 } 405 406 outs() << "Wrote native object file '" << OutputName << "'\n"; 407 } 408 409 return 0; 410 } 411