1 //===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===// 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 file implements the Link Time Optimization library. This library is 11 // intended to be used by linker to optimize code at link time. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "LTOModule.h" 16 #include "LTOCodeGenerator.h" 17 #include "llvm/Constants.h" 18 #include "llvm/DerivedTypes.h" 19 #include "llvm/Linker.h" 20 #include "llvm/LLVMContext.h" 21 #include "llvm/Module.h" 22 #include "llvm/PassManager.h" 23 #include "llvm/ADT/StringExtras.h" 24 #include "llvm/ADT/Triple.h" 25 #include "llvm/Analysis/Passes.h" 26 #include "llvm/Analysis/Verifier.h" 27 #include "llvm/Bitcode/ReaderWriter.h" 28 #include "llvm/MC/MCAsmInfo.h" 29 #include "llvm/MC/MCContext.h" 30 #include "llvm/MC/SubtargetFeature.h" 31 #include "llvm/Target/Mangler.h" 32 #include "llvm/Target/TargetOptions.h" 33 #include "llvm/Target/TargetData.h" 34 #include "llvm/Target/TargetMachine.h" 35 #include "llvm/Target/TargetRegisterInfo.h" 36 #include "llvm/Support/CommandLine.h" 37 #include "llvm/Support/FormattedStream.h" 38 #include "llvm/Support/MemoryBuffer.h" 39 #include "llvm/Support/SystemUtils.h" 40 #include "llvm/Support/ToolOutputFile.h" 41 #include "llvm/Support/Host.h" 42 #include "llvm/Support/Program.h" 43 #include "llvm/Support/Signals.h" 44 #include "llvm/Support/TargetRegistry.h" 45 #include "llvm/Support/TargetSelect.h" 46 #include "llvm/Support/system_error.h" 47 #include "llvm/Config/config.h" 48 #include "llvm/Transforms/IPO.h" 49 #include "llvm/Transforms/IPO/PassManagerBuilder.h" 50 #include <cstdlib> 51 #include <unistd.h> 52 #include <fcntl.h> 53 54 55 using namespace llvm; 56 57 static cl::opt<bool> DisableInline("disable-inlining", 58 cl::desc("Do not run the inliner pass")); 59 60 61 const char* LTOCodeGenerator::getVersionString() 62 { 63 #ifdef LLVM_VERSION_INFO 64 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO; 65 #else 66 return PACKAGE_NAME " version " PACKAGE_VERSION; 67 #endif 68 } 69 70 71 LTOCodeGenerator::LTOCodeGenerator() 72 : _context(getGlobalContext()), 73 _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL), 74 _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false), 75 _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC), 76 _nativeObjectFile(NULL) 77 { 78 InitializeAllTargets(); 79 InitializeAllTargetMCs(); 80 InitializeAllAsmPrinters(); 81 } 82 83 LTOCodeGenerator::~LTOCodeGenerator() 84 { 85 delete _target; 86 delete _nativeObjectFile; 87 } 88 89 90 91 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) 92 { 93 94 if(mod->getLLVVMModule()->MaterializeAllPermanently(&errMsg)) 95 return true; 96 97 bool ret = _linker.LinkInModule(mod->getLLVVMModule(), &errMsg); 98 99 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs(); 100 for (int i = 0, e = undefs.size(); i != e; ++i) 101 _asmUndefinedRefs[undefs[i]] = 1; 102 103 return ret; 104 } 105 106 107 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg) 108 { 109 switch (debug) { 110 case LTO_DEBUG_MODEL_NONE: 111 _emitDwarfDebugInfo = false; 112 return false; 113 114 case LTO_DEBUG_MODEL_DWARF: 115 _emitDwarfDebugInfo = true; 116 return false; 117 } 118 errMsg = "unknown debug format"; 119 return true; 120 } 121 122 123 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model, 124 std::string& errMsg) 125 { 126 switch (model) { 127 case LTO_CODEGEN_PIC_MODEL_STATIC: 128 case LTO_CODEGEN_PIC_MODEL_DYNAMIC: 129 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC: 130 _codeModel = model; 131 return false; 132 } 133 errMsg = "unknown pic model"; 134 return true; 135 } 136 137 void LTOCodeGenerator::setCpu(const char* mCpu) 138 { 139 _mCpu = mCpu; 140 } 141 142 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym) 143 { 144 _mustPreserveSymbols[sym] = 1; 145 } 146 147 148 bool LTOCodeGenerator::writeMergedModules(const char *path, 149 std::string &errMsg) { 150 if (determineTarget(errMsg)) 151 return true; 152 153 // mark which symbols can not be internalized 154 applyScopeRestrictions(); 155 156 // create output file 157 std::string ErrInfo; 158 tool_output_file Out(path, ErrInfo, 159 raw_fd_ostream::F_Binary); 160 if (!ErrInfo.empty()) { 161 errMsg = "could not open bitcode file for writing: "; 162 errMsg += path; 163 return true; 164 } 165 166 // write bitcode to it 167 WriteBitcodeToFile(_linker.getModule(), Out.os()); 168 Out.os().close(); 169 170 if (Out.os().has_error()) { 171 errMsg = "could not write bitcode file: "; 172 errMsg += path; 173 Out.os().clear_error(); 174 return true; 175 } 176 177 Out.keep(); 178 return false; 179 } 180 181 182 bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg) 183 { 184 // make unique temp .o file to put generated object file 185 sys::PathWithStatus uniqueObjPath("lto-llvm.o"); 186 if ( uniqueObjPath.createTemporaryFileOnDisk(false, &errMsg) ) { 187 uniqueObjPath.eraseFromDisk(); 188 return true; 189 } 190 sys::RemoveFileOnSignal(uniqueObjPath); 191 192 // generate object file 193 bool genResult = false; 194 tool_output_file objFile(uniqueObjPath.c_str(), errMsg); 195 if (!errMsg.empty()) 196 return true; 197 genResult = this->generateObjectFile(objFile.os(), errMsg); 198 objFile.os().close(); 199 if (objFile.os().has_error()) { 200 objFile.os().clear_error(); 201 return true; 202 } 203 objFile.keep(); 204 if ( genResult ) { 205 uniqueObjPath.eraseFromDisk(); 206 return true; 207 } 208 209 _nativeObjectPath = uniqueObjPath.str(); 210 *name = _nativeObjectPath.c_str(); 211 return false; 212 } 213 214 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) 215 { 216 const char *name; 217 if (compile_to_file(&name, errMsg)) 218 return NULL; 219 220 // remove old buffer if compile() called twice 221 delete _nativeObjectFile; 222 223 // read .o file into memory buffer 224 OwningPtr<MemoryBuffer> BuffPtr; 225 if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) { 226 errMsg = ec.message(); 227 return NULL; 228 } 229 _nativeObjectFile = BuffPtr.take(); 230 231 // remove temp files 232 sys::Path(_nativeObjectPath).eraseFromDisk(); 233 234 // return buffer, unless error 235 if ( _nativeObjectFile == NULL ) 236 return NULL; 237 *length = _nativeObjectFile->getBufferSize(); 238 return _nativeObjectFile->getBufferStart(); 239 } 240 241 bool LTOCodeGenerator::determineTarget(std::string& errMsg) 242 { 243 if ( _target == NULL ) { 244 std::string Triple = _linker.getModule()->getTargetTriple(); 245 if (Triple.empty()) 246 Triple = sys::getHostTriple(); 247 248 // create target machine from info for merged modules 249 const Target *march = TargetRegistry::lookupTarget(Triple, errMsg); 250 if ( march == NULL ) 251 return true; 252 253 // The relocation model is actually a static member of TargetMachine 254 // and needs to be set before the TargetMachine is instantiated. 255 Reloc::Model RelocModel = Reloc::Default; 256 switch( _codeModel ) { 257 case LTO_CODEGEN_PIC_MODEL_STATIC: 258 RelocModel = Reloc::Static; 259 break; 260 case LTO_CODEGEN_PIC_MODEL_DYNAMIC: 261 RelocModel = Reloc::PIC_; 262 break; 263 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC: 264 RelocModel = Reloc::DynamicNoPIC; 265 break; 266 } 267 268 // construct LTOModule, hand over ownership of module and target 269 SubtargetFeatures Features; 270 Features.getDefaultSubtargetFeatures(llvm::Triple(Triple)); 271 std::string FeatureStr = Features.getString(); 272 _target = march->createTargetMachine(Triple, _mCpu, FeatureStr, 273 RelocModel); 274 } 275 return false; 276 } 277 278 void LTOCodeGenerator::applyRestriction(GlobalValue &GV, 279 std::vector<const char*> &mustPreserveList, 280 SmallPtrSet<GlobalValue*, 8> &asmUsed, 281 Mangler &mangler) { 282 SmallString<64> Buffer; 283 mangler.getNameWithPrefix(Buffer, &GV, false); 284 285 if (GV.isDeclaration()) 286 return; 287 if (_mustPreserveSymbols.count(Buffer)) 288 mustPreserveList.push_back(GV.getName().data()); 289 if (_asmUndefinedRefs.count(Buffer)) 290 asmUsed.insert(&GV); 291 } 292 293 static void findUsedValues(GlobalVariable *LLVMUsed, 294 SmallPtrSet<GlobalValue*, 8> &UsedValues) { 295 if (LLVMUsed == 0) return; 296 297 ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer()); 298 if (Inits == 0) return; 299 300 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i) 301 if (GlobalValue *GV = 302 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts())) 303 UsedValues.insert(GV); 304 } 305 306 void LTOCodeGenerator::applyScopeRestrictions() { 307 if (_scopeRestrictionsDone) return; 308 Module *mergedModule = _linker.getModule(); 309 310 // Start off with a verification pass. 311 PassManager passes; 312 passes.add(createVerifierPass()); 313 314 // mark which symbols can not be internalized 315 MCContext Context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(), NULL); 316 Mangler mangler(Context, *_target->getTargetData()); 317 std::vector<const char*> mustPreserveList; 318 SmallPtrSet<GlobalValue*, 8> asmUsed; 319 320 for (Module::iterator f = mergedModule->begin(), 321 e = mergedModule->end(); f != e; ++f) 322 applyRestriction(*f, mustPreserveList, asmUsed, mangler); 323 for (Module::global_iterator v = mergedModule->global_begin(), 324 e = mergedModule->global_end(); v != e; ++v) 325 applyRestriction(*v, mustPreserveList, asmUsed, mangler); 326 for (Module::alias_iterator a = mergedModule->alias_begin(), 327 e = mergedModule->alias_end(); a != e; ++a) 328 applyRestriction(*a, mustPreserveList, asmUsed, mangler); 329 330 GlobalVariable *LLVMCompilerUsed = 331 mergedModule->getGlobalVariable("llvm.compiler.used"); 332 findUsedValues(LLVMCompilerUsed, asmUsed); 333 if (LLVMCompilerUsed) 334 LLVMCompilerUsed->eraseFromParent(); 335 336 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(_context); 337 std::vector<Constant*> asmUsed2; 338 for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = asmUsed.begin(), 339 e = asmUsed.end(); i !=e; ++i) { 340 GlobalValue *GV = *i; 341 Constant *c = ConstantExpr::getBitCast(GV, i8PTy); 342 asmUsed2.push_back(c); 343 } 344 345 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size()); 346 LLVMCompilerUsed = 347 new llvm::GlobalVariable(*mergedModule, ATy, false, 348 llvm::GlobalValue::AppendingLinkage, 349 llvm::ConstantArray::get(ATy, asmUsed2), 350 "llvm.compiler.used"); 351 352 LLVMCompilerUsed->setSection("llvm.metadata"); 353 354 passes.add(createInternalizePass(mustPreserveList)); 355 356 // apply scope restrictions 357 passes.run(*mergedModule); 358 359 _scopeRestrictionsDone = true; 360 } 361 362 /// Optimize merged modules using various IPO passes 363 bool LTOCodeGenerator::generateObjectFile(raw_ostream &out, 364 std::string &errMsg) { 365 if ( this->determineTarget(errMsg) ) 366 return true; 367 368 // mark which symbols can not be internalized 369 this->applyScopeRestrictions(); 370 371 Module* mergedModule = _linker.getModule(); 372 373 // if options were requested, set them 374 if ( !_codegenOptions.empty() ) 375 cl::ParseCommandLineOptions(_codegenOptions.size(), 376 const_cast<char **>(&_codegenOptions[0])); 377 378 // Instantiate the pass manager to organize the passes. 379 PassManager passes; 380 381 // Start off with a verification pass. 382 passes.add(createVerifierPass()); 383 384 // Add an appropriate TargetData instance for this module... 385 passes.add(new TargetData(*_target->getTargetData())); 386 387 PassManagerBuilder().populateLTOPassManager(passes, /*Internalize=*/ false, 388 !DisableInline); 389 390 // Make sure everything is still good. 391 passes.add(createVerifierPass()); 392 393 FunctionPassManager *codeGenPasses = new FunctionPassManager(mergedModule); 394 395 codeGenPasses->add(new TargetData(*_target->getTargetData())); 396 397 formatted_raw_ostream Out(out); 398 399 if (_target->addPassesToEmitFile(*codeGenPasses, Out, 400 TargetMachine::CGFT_ObjectFile, 401 CodeGenOpt::Aggressive)) { 402 errMsg = "target file type not supported"; 403 return true; 404 } 405 406 // Run our queue of passes all at once now, efficiently. 407 passes.run(*mergedModule); 408 409 // Run the code generator, and write assembly file 410 codeGenPasses->doInitialization(); 411 412 for (Module::iterator 413 it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it) 414 if (!it->isDeclaration()) 415 codeGenPasses->run(*it); 416 417 codeGenPasses->doFinalization(); 418 delete codeGenPasses; 419 420 return false; // success 421 } 422 423 424 /// Optimize merged modules using various IPO passes 425 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options) 426 { 427 for (std::pair<StringRef, StringRef> o = getToken(options); 428 !o.first.empty(); o = getToken(o.second)) { 429 // ParseCommandLineOptions() expects argv[0] to be program name. 430 // Lazily add that. 431 if ( _codegenOptions.empty() ) 432 _codegenOptions.push_back("libLTO"); 433 _codegenOptions.push_back(strdup(o.first.str().c_str())); 434 } 435 } 436
