1 //===- llvm-link.cpp - Low-level LLVM linker ------------------------------===// 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 utility may be invoked in the following manner: 11 // llvm-link a.bc b.bc c.bc -o x.bc 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/ADT/STLExtras.h" 16 #include "llvm/Bitcode/ReaderWriter.h" 17 #include "llvm/IR/AutoUpgrade.h" 18 #include "llvm/IR/DiagnosticInfo.h" 19 #include "llvm/IR/DiagnosticPrinter.h" 20 #include "llvm/IR/LLVMContext.h" 21 #include "llvm/IR/Module.h" 22 #include "llvm/IR/ModuleSummaryIndex.h" 23 #include "llvm/IR/Verifier.h" 24 #include "llvm/IRReader/IRReader.h" 25 #include "llvm/Linker/Linker.h" 26 #include "llvm/Object/ModuleSummaryIndexObjectFile.h" 27 #include "llvm/Support/CommandLine.h" 28 #include "llvm/Support/FileSystem.h" 29 #include "llvm/Support/ManagedStatic.h" 30 #include "llvm/Support/Path.h" 31 #include "llvm/Support/PrettyStackTrace.h" 32 #include "llvm/Support/Signals.h" 33 #include "llvm/Support/SourceMgr.h" 34 #include "llvm/Support/SystemUtils.h" 35 #include "llvm/Support/ToolOutputFile.h" 36 #include "llvm/Transforms/Utils/FunctionImportUtils.h" 37 38 #include <memory> 39 #include <utility> 40 using namespace llvm; 41 42 static cl::list<std::string> 43 InputFilenames(cl::Positional, cl::OneOrMore, 44 cl::desc("<input bitcode files>")); 45 46 static cl::list<std::string> OverridingInputs( 47 "override", cl::ZeroOrMore, cl::value_desc("filename"), 48 cl::desc( 49 "input bitcode file which can override previously defined symbol(s)")); 50 51 // Option to simulate function importing for testing. This enables using 52 // llvm-link to simulate ThinLTO backend processes. 53 static cl::list<std::string> Imports( 54 "import", cl::ZeroOrMore, cl::value_desc("function:filename"), 55 cl::desc("Pair of function name and filename, where function should be " 56 "imported from bitcode in filename")); 57 58 // Option to support testing of function importing. The module summary 59 // must be specified in the case were we request imports via the -import 60 // option, as well as when compiling any module with functions that may be 61 // exported (imported by a different llvm-link -import invocation), to ensure 62 // consistent promotion and renaming of locals. 63 static cl::opt<std::string> 64 SummaryIndex("summary-index", cl::desc("Module summary index filename"), 65 cl::init(""), cl::value_desc("filename")); 66 67 static cl::opt<std::string> 68 OutputFilename("o", cl::desc("Override output filename"), cl::init("-"), 69 cl::value_desc("filename")); 70 71 static cl::opt<bool> 72 Internalize("internalize", cl::desc("Internalize linked symbols")); 73 74 static cl::opt<bool> 75 DisableDITypeMap("disable-debug-info-type-map", 76 cl::desc("Don't use a uniquing type map for debug info")); 77 78 static cl::opt<bool> 79 OnlyNeeded("only-needed", cl::desc("Link only needed symbols")); 80 81 static cl::opt<bool> 82 Force("f", cl::desc("Enable binary output on terminals")); 83 84 static cl::opt<bool> 85 OutputAssembly("S", 86 cl::desc("Write output as LLVM assembly"), cl::Hidden); 87 88 static cl::opt<bool> 89 Verbose("v", cl::desc("Print information about actions taken")); 90 91 static cl::opt<bool> 92 DumpAsm("d", cl::desc("Print assembly as linked"), cl::Hidden); 93 94 static cl::opt<bool> 95 SuppressWarnings("suppress-warnings", cl::desc("Suppress all linking warnings"), 96 cl::init(false)); 97 98 static cl::opt<bool> PreserveBitcodeUseListOrder( 99 "preserve-bc-uselistorder", 100 cl::desc("Preserve use-list order when writing LLVM bitcode."), 101 cl::init(true), cl::Hidden); 102 103 static cl::opt<bool> PreserveAssemblyUseListOrder( 104 "preserve-ll-uselistorder", 105 cl::desc("Preserve use-list order when writing LLVM assembly."), 106 cl::init(false), cl::Hidden); 107 108 // Read the specified bitcode file in and return it. This routine searches the 109 // link path for the specified file to try to find it... 110 // 111 static std::unique_ptr<Module> loadFile(const char *argv0, 112 const std::string &FN, 113 LLVMContext &Context, 114 bool MaterializeMetadata = true) { 115 SMDiagnostic Err; 116 if (Verbose) errs() << "Loading '" << FN << "'\n"; 117 std::unique_ptr<Module> Result = 118 getLazyIRFileModule(FN, Err, Context, !MaterializeMetadata); 119 if (!Result) { 120 Err.print(argv0, errs()); 121 return nullptr; 122 } 123 124 if (MaterializeMetadata) { 125 Result->materializeMetadata(); 126 UpgradeDebugInfo(*Result); 127 } 128 129 return Result; 130 } 131 132 namespace { 133 134 /// Helper to load on demand a Module from file and cache it for subsequent 135 /// queries during function importing. 136 class ModuleLazyLoaderCache { 137 /// Cache of lazily loaded module for import. 138 StringMap<std::unique_ptr<Module>> ModuleMap; 139 140 /// Retrieve a Module from the cache or lazily load it on demand. 141 std::function<std::unique_ptr<Module>(const char *argv0, 142 const std::string &FileName)> 143 createLazyModule; 144 145 public: 146 /// Create the loader, Module will be initialized in \p Context. 147 ModuleLazyLoaderCache(std::function<std::unique_ptr<Module>( 148 const char *argv0, const std::string &FileName)> 149 createLazyModule) 150 : createLazyModule(std::move(createLazyModule)) {} 151 152 /// Retrieve a Module from the cache or lazily load it on demand. 153 Module &operator()(const char *argv0, const std::string &FileName); 154 155 std::unique_ptr<Module> takeModule(const std::string &FileName) { 156 auto I = ModuleMap.find(FileName); 157 assert(I != ModuleMap.end()); 158 std::unique_ptr<Module> Ret = std::move(I->second); 159 ModuleMap.erase(I); 160 return Ret; 161 } 162 }; 163 164 // Get a Module for \p FileName from the cache, or load it lazily. 165 Module &ModuleLazyLoaderCache::operator()(const char *argv0, 166 const std::string &Identifier) { 167 auto &Module = ModuleMap[Identifier]; 168 if (!Module) 169 Module = createLazyModule(argv0, Identifier); 170 return *Module; 171 } 172 } // anonymous namespace 173 174 static void diagnosticHandler(const DiagnosticInfo &DI) { 175 unsigned Severity = DI.getSeverity(); 176 switch (Severity) { 177 case DS_Error: 178 errs() << "ERROR: "; 179 break; 180 case DS_Warning: 181 if (SuppressWarnings) 182 return; 183 errs() << "WARNING: "; 184 break; 185 case DS_Remark: 186 case DS_Note: 187 llvm_unreachable("Only expecting warnings and errors"); 188 } 189 190 DiagnosticPrinterRawOStream DP(errs()); 191 DI.print(DP); 192 errs() << '\n'; 193 } 194 195 static void diagnosticHandlerWithContext(const DiagnosticInfo &DI, void *C) { 196 diagnosticHandler(DI); 197 } 198 199 /// Import any functions requested via the -import option. 200 static bool importFunctions(const char *argv0, LLVMContext &Context, 201 Linker &L) { 202 if (SummaryIndex.empty()) 203 return true; 204 ErrorOr<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr = 205 llvm::getModuleSummaryIndexForFile(SummaryIndex, diagnosticHandler); 206 std::error_code EC = IndexOrErr.getError(); 207 if (EC) { 208 errs() << EC.message() << '\n'; 209 return false; 210 } 211 auto Index = std::move(IndexOrErr.get()); 212 213 // Map of Module -> List of globals to import from the Module 214 std::map<StringRef, DenseSet<const GlobalValue *>> ModuleToGlobalsToImportMap; 215 auto ModuleLoader = [&Context](const char *argv0, 216 const std::string &Identifier) { 217 return loadFile(argv0, Identifier, Context, false); 218 }; 219 ModuleLazyLoaderCache ModuleLoaderCache(ModuleLoader); 220 for (const auto &Import : Imports) { 221 // Identify the requested function and its bitcode source file. 222 size_t Idx = Import.find(':'); 223 if (Idx == std::string::npos) { 224 errs() << "Import parameter bad format: " << Import << "\n"; 225 return false; 226 } 227 std::string FunctionName = Import.substr(0, Idx); 228 std::string FileName = Import.substr(Idx + 1, std::string::npos); 229 230 // Load the specified source module. 231 auto &SrcModule = ModuleLoaderCache(argv0, FileName); 232 233 if (verifyModule(SrcModule, &errs())) { 234 errs() << argv0 << ": " << FileName 235 << ": error: input module is broken!\n"; 236 return false; 237 } 238 239 Function *F = SrcModule.getFunction(FunctionName); 240 if (!F) { 241 errs() << "Ignoring import request for non-existent function " 242 << FunctionName << " from " << FileName << "\n"; 243 continue; 244 } 245 // We cannot import weak_any functions without possibly affecting the 246 // order they are seen and selected by the linker, changing program 247 // semantics. 248 if (F->hasWeakAnyLinkage()) { 249 errs() << "Ignoring import request for weak-any function " << FunctionName 250 << " from " << FileName << "\n"; 251 continue; 252 } 253 254 if (Verbose) 255 errs() << "Importing " << FunctionName << " from " << FileName << "\n"; 256 257 auto &Entry = ModuleToGlobalsToImportMap[SrcModule.getModuleIdentifier()]; 258 Entry.insert(F); 259 260 F->materialize(); 261 } 262 263 // Do the actual import of globals now, one Module at a time 264 for (auto &GlobalsToImportPerModule : ModuleToGlobalsToImportMap) { 265 // Get the module for the import 266 auto &GlobalsToImport = GlobalsToImportPerModule.second; 267 std::unique_ptr<Module> SrcModule = 268 ModuleLoaderCache.takeModule(GlobalsToImportPerModule.first); 269 assert(&Context == &SrcModule->getContext() && "Context mismatch"); 270 271 // If modules were created with lazy metadata loading, materialize it 272 // now, before linking it (otherwise this will be a noop). 273 SrcModule->materializeMetadata(); 274 UpgradeDebugInfo(*SrcModule); 275 276 // Linkage Promotion and renaming 277 if (renameModuleForThinLTO(*SrcModule, *Index, &GlobalsToImport)) 278 return true; 279 280 // Instruct the linker to not automatically import linkonce defintion. 281 unsigned Flags = Linker::Flags::DontForceLinkLinkonceODR; 282 283 if (L.linkInModule(std::move(SrcModule), Flags, &GlobalsToImport)) 284 return false; 285 } 286 287 return true; 288 } 289 290 static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L, 291 const cl::list<std::string> &Files, 292 unsigned Flags) { 293 // Filter out flags that don't apply to the first file we load. 294 unsigned ApplicableFlags = Flags & Linker::Flags::OverrideFromSrc; 295 for (const auto &File : Files) { 296 std::unique_ptr<Module> M = loadFile(argv0, File, Context); 297 if (!M.get()) { 298 errs() << argv0 << ": error loading file '" << File << "'\n"; 299 return false; 300 } 301 302 // Note that when ODR merging types cannot verify input files in here When 303 // doing that debug metadata in the src module might already be pointing to 304 // the destination. 305 if (DisableDITypeMap && verifyModule(*M, &errs())) { 306 errs() << argv0 << ": " << File << ": error: input module is broken!\n"; 307 return false; 308 } 309 310 // If a module summary index is supplied, load it so linkInModule can treat 311 // local functions/variables as exported and promote if necessary. 312 if (!SummaryIndex.empty()) { 313 ErrorOr<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr = 314 llvm::getModuleSummaryIndexForFile(SummaryIndex, diagnosticHandler); 315 std::error_code EC = IndexOrErr.getError(); 316 if (EC) { 317 errs() << EC.message() << '\n'; 318 return false; 319 } 320 auto Index = std::move(IndexOrErr.get()); 321 322 // Promotion 323 if (renameModuleForThinLTO(*M, *Index)) 324 return true; 325 } 326 327 if (Verbose) 328 errs() << "Linking in '" << File << "'\n"; 329 330 if (L.linkInModule(std::move(M), ApplicableFlags)) 331 return false; 332 // All linker flags apply to linking of subsequent files. 333 ApplicableFlags = Flags; 334 } 335 336 return true; 337 } 338 339 int main(int argc, char **argv) { 340 // Print a stack trace if we signal out. 341 sys::PrintStackTraceOnErrorSignal(argv[0]); 342 PrettyStackTraceProgram X(argc, argv); 343 344 LLVMContext Context; 345 Context.setDiagnosticHandler(diagnosticHandlerWithContext, nullptr, true); 346 347 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit. 348 cl::ParseCommandLineOptions(argc, argv, "llvm linker\n"); 349 350 if (!DisableDITypeMap) 351 Context.enableDebugTypeODRUniquing(); 352 353 auto Composite = make_unique<Module>("llvm-link", Context); 354 Linker L(*Composite); 355 356 unsigned Flags = Linker::Flags::None; 357 if (Internalize) 358 Flags |= Linker::Flags::InternalizeLinkedSymbols; 359 if (OnlyNeeded) 360 Flags |= Linker::Flags::LinkOnlyNeeded; 361 362 // First add all the regular input files 363 if (!linkFiles(argv[0], Context, L, InputFilenames, Flags)) 364 return 1; 365 366 // Next the -override ones. 367 if (!linkFiles(argv[0], Context, L, OverridingInputs, 368 Flags | Linker::Flags::OverrideFromSrc)) 369 return 1; 370 371 // Import any functions requested via -import 372 if (!importFunctions(argv[0], Context, L)) 373 return 1; 374 375 if (DumpAsm) errs() << "Here's the assembly:\n" << *Composite; 376 377 std::error_code EC; 378 tool_output_file Out(OutputFilename, EC, sys::fs::F_None); 379 if (EC) { 380 errs() << EC.message() << '\n'; 381 return 1; 382 } 383 384 if (verifyModule(*Composite, &errs())) { 385 errs() << argv[0] << ": error: linked module is broken!\n"; 386 return 1; 387 } 388 389 if (Verbose) errs() << "Writing bitcode...\n"; 390 if (OutputAssembly) { 391 Composite->print(Out.os(), nullptr, PreserveAssemblyUseListOrder); 392 } else if (Force || !CheckBitcodeOutputToConsole(Out.os(), true)) 393 WriteBitcodeToFile(Composite.get(), Out.os(), PreserveBitcodeUseListOrder); 394 395 // Declare success. 396 Out.keep(); 397 398 return 0; 399 } 400
