LTOCodeGenerator.cpp revision 9780d352b9108d49097970f6686fd61aba58d7fc
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 "LTOCodeGenerator.h" 16#include "LTOModule.h" 17#include "llvm/Constants.h" 18#include "llvm/DataLayout.h" 19#include "llvm/DerivedTypes.h" 20#include "llvm/Linker.h" 21#include "llvm/LLVMContext.h" 22#include "llvm/Module.h" 23#include "llvm/PassManager.h" 24#include "llvm/Analysis/Passes.h" 25#include "llvm/Analysis/Verifier.h" 26#include "llvm/Bitcode/ReaderWriter.h" 27#include "llvm/Config/config.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/TargetMachine.h" 34#include "llvm/Target/TargetRegisterInfo.h" 35#include "llvm/Transforms/IPO.h" 36#include "llvm/Transforms/IPO/PassManagerBuilder.h" 37#include "llvm/Support/CommandLine.h" 38#include "llvm/Support/FormattedStream.h" 39#include "llvm/Support/MemoryBuffer.h" 40#include "llvm/Support/ToolOutputFile.h" 41#include "llvm/Support/Host.h" 42#include "llvm/Support/Signals.h" 43#include "llvm/Support/TargetRegistry.h" 44#include "llvm/Support/TargetSelect.h" 45#include "llvm/Support/system_error.h" 46#include "llvm/ADT/StringExtras.h" 47using namespace llvm; 48 49static cl::opt<bool> 50DisableInline("disable-inlining", cl::init(false), 51 cl::desc("Do not run the inliner pass")); 52 53static cl::opt<bool> 54DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false), 55 cl::desc("Do not run the GVN load PRE pass")); 56 57const char* LTOCodeGenerator::getVersionString() { 58#ifdef LLVM_VERSION_INFO 59 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO; 60#else 61 return PACKAGE_NAME " version " PACKAGE_VERSION; 62#endif 63} 64 65LTOCodeGenerator::LTOCodeGenerator() 66 : _context(getGlobalContext()), 67 _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL), 68 _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false), 69 _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC), 70 _nativeObjectFile(NULL) { 71 InitializeAllTargets(); 72 InitializeAllTargetMCs(); 73 InitializeAllAsmPrinters(); 74} 75 76LTOCodeGenerator::~LTOCodeGenerator() { 77 delete _target; 78 delete _nativeObjectFile; 79 80 for (std::vector<char*>::iterator I = _codegenOptions.begin(), 81 E = _codegenOptions.end(); I != E; ++I) 82 free(*I); 83} 84 85bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) { 86 bool ret = _linker.LinkInModule(mod->getLLVVMModule(), &errMsg); 87 88 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs(); 89 for (int i = 0, e = undefs.size(); i != e; ++i) 90 _asmUndefinedRefs[undefs[i]] = 1; 91 92 return ret; 93} 94 95bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, 96 std::string& errMsg) { 97 switch (debug) { 98 case LTO_DEBUG_MODEL_NONE: 99 _emitDwarfDebugInfo = false; 100 return false; 101 102 case LTO_DEBUG_MODEL_DWARF: 103 _emitDwarfDebugInfo = true; 104 return false; 105 } 106 llvm_unreachable("Unknown debug format!"); 107} 108 109bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model, 110 std::string& errMsg) { 111 switch (model) { 112 case LTO_CODEGEN_PIC_MODEL_STATIC: 113 case LTO_CODEGEN_PIC_MODEL_DYNAMIC: 114 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC: 115 _codeModel = model; 116 return false; 117 } 118 llvm_unreachable("Unknown PIC model!"); 119} 120 121bool LTOCodeGenerator::writeMergedModules(const char *path, 122 std::string &errMsg) { 123 if (determineTarget(errMsg)) 124 return true; 125 126 // mark which symbols can not be internalized 127 applyScopeRestrictions(); 128 129 // create output file 130 std::string ErrInfo; 131 tool_output_file Out(path, ErrInfo, 132 raw_fd_ostream::F_Binary); 133 if (!ErrInfo.empty()) { 134 errMsg = "could not open bitcode file for writing: "; 135 errMsg += path; 136 return true; 137 } 138 139 // write bitcode to it 140 WriteBitcodeToFile(_linker.getModule(), Out.os()); 141 Out.os().close(); 142 143 if (Out.os().has_error()) { 144 errMsg = "could not write bitcode file: "; 145 errMsg += path; 146 Out.os().clear_error(); 147 return true; 148 } 149 150 Out.keep(); 151 return false; 152} 153 154bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg) { 155 // make unique temp .o file to put generated object file 156 sys::PathWithStatus uniqueObjPath("lto-llvm.o"); 157 if (uniqueObjPath.createTemporaryFileOnDisk(false, &errMsg)) { 158 uniqueObjPath.eraseFromDisk(); 159 return true; 160 } 161 sys::RemoveFileOnSignal(uniqueObjPath); 162 163 // generate object file 164 bool genResult = false; 165 tool_output_file objFile(uniqueObjPath.c_str(), errMsg); 166 if (!errMsg.empty()) { 167 uniqueObjPath.eraseFromDisk(); 168 return true; 169 } 170 171 genResult = this->generateObjectFile(objFile.os(), errMsg); 172 objFile.os().close(); 173 if (objFile.os().has_error()) { 174 objFile.os().clear_error(); 175 uniqueObjPath.eraseFromDisk(); 176 return true; 177 } 178 179 objFile.keep(); 180 if (genResult) { 181 uniqueObjPath.eraseFromDisk(); 182 return true; 183 } 184 185 _nativeObjectPath = uniqueObjPath.str(); 186 *name = _nativeObjectPath.c_str(); 187 return false; 188} 189 190const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) { 191 const char *name; 192 if (compile_to_file(&name, errMsg)) 193 return NULL; 194 195 // remove old buffer if compile() called twice 196 delete _nativeObjectFile; 197 198 // read .o file into memory buffer 199 OwningPtr<MemoryBuffer> BuffPtr; 200 if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) { 201 errMsg = ec.message(); 202 sys::Path(_nativeObjectPath).eraseFromDisk(); 203 return NULL; 204 } 205 _nativeObjectFile = BuffPtr.take(); 206 207 // remove temp files 208 sys::Path(_nativeObjectPath).eraseFromDisk(); 209 210 // return buffer, unless error 211 if (_nativeObjectFile == NULL) 212 return NULL; 213 *length = _nativeObjectFile->getBufferSize(); 214 return _nativeObjectFile->getBufferStart(); 215} 216 217bool LTOCodeGenerator::determineTarget(std::string& errMsg) { 218 if (_target != NULL) 219 return false; 220 221 std::string TripleStr = _linker.getModule()->getTargetTriple(); 222 if (TripleStr.empty()) 223 TripleStr = sys::getDefaultTargetTriple(); 224 llvm::Triple Triple(TripleStr); 225 226 // create target machine from info for merged modules 227 const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg); 228 if (march == NULL) 229 return true; 230 231 // The relocation model is actually a static member of TargetMachine and 232 // needs to be set before the TargetMachine is instantiated. 233 Reloc::Model RelocModel = Reloc::Default; 234 switch (_codeModel) { 235 case LTO_CODEGEN_PIC_MODEL_STATIC: 236 RelocModel = Reloc::Static; 237 break; 238 case LTO_CODEGEN_PIC_MODEL_DYNAMIC: 239 RelocModel = Reloc::PIC_; 240 break; 241 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC: 242 RelocModel = Reloc::DynamicNoPIC; 243 break; 244 } 245 246 // construct LTOModule, hand over ownership of module and target 247 SubtargetFeatures Features; 248 Features.getDefaultSubtargetFeatures(Triple); 249 std::string FeatureStr = Features.getString(); 250 // Set a default CPU for Darwin triples. 251 if (_mCpu.empty() && Triple.isOSDarwin()) { 252 if (Triple.getArch() == llvm::Triple::x86_64) 253 _mCpu = "core2"; 254 else if (Triple.getArch() == llvm::Triple::x86) 255 _mCpu = "yonah"; 256 } 257 TargetOptions Options; 258 LTOModule::getTargetOptions(Options); 259 _target = march->createTargetMachine(TripleStr, _mCpu, FeatureStr, Options, 260 RelocModel, CodeModel::Default, 261 CodeGenOpt::Aggressive); 262 return false; 263} 264 265void LTOCodeGenerator:: 266applyRestriction(GlobalValue &GV, 267 std::vector<const char*> &mustPreserveList, 268 SmallPtrSet<GlobalValue*, 8> &asmUsed, 269 Mangler &mangler) { 270 SmallString<64> Buffer; 271 mangler.getNameWithPrefix(Buffer, &GV, false); 272 273 if (GV.isDeclaration()) 274 return; 275 if (_mustPreserveSymbols.count(Buffer)) 276 mustPreserveList.push_back(GV.getName().data()); 277 if (_asmUndefinedRefs.count(Buffer)) 278 asmUsed.insert(&GV); 279} 280 281static void findUsedValues(GlobalVariable *LLVMUsed, 282 SmallPtrSet<GlobalValue*, 8> &UsedValues) { 283 if (LLVMUsed == 0) return; 284 285 ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer()); 286 if (Inits == 0) return; 287 288 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i) 289 if (GlobalValue *GV = 290 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts())) 291 UsedValues.insert(GV); 292} 293 294void LTOCodeGenerator::applyScopeRestrictions() { 295 if (_scopeRestrictionsDone) return; 296 Module *mergedModule = _linker.getModule(); 297 298 // Start off with a verification pass. 299 PassManager passes; 300 passes.add(createVerifierPass()); 301 302 // mark which symbols can not be internalized 303 MCContext Context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(),NULL); 304 Mangler mangler(Context, *_target->getDataLayout()); 305 std::vector<const char*> mustPreserveList; 306 SmallPtrSet<GlobalValue*, 8> asmUsed; 307 308 for (Module::iterator f = mergedModule->begin(), 309 e = mergedModule->end(); f != e; ++f) 310 applyRestriction(*f, mustPreserveList, asmUsed, mangler); 311 for (Module::global_iterator v = mergedModule->global_begin(), 312 e = mergedModule->global_end(); v != e; ++v) 313 applyRestriction(*v, mustPreserveList, asmUsed, mangler); 314 for (Module::alias_iterator a = mergedModule->alias_begin(), 315 e = mergedModule->alias_end(); a != e; ++a) 316 applyRestriction(*a, mustPreserveList, asmUsed, mangler); 317 318 GlobalVariable *LLVMCompilerUsed = 319 mergedModule->getGlobalVariable("llvm.compiler.used"); 320 findUsedValues(LLVMCompilerUsed, asmUsed); 321 if (LLVMCompilerUsed) 322 LLVMCompilerUsed->eraseFromParent(); 323 324 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(_context); 325 std::vector<Constant*> asmUsed2; 326 for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = asmUsed.begin(), 327 e = asmUsed.end(); i !=e; ++i) { 328 GlobalValue *GV = *i; 329 Constant *c = ConstantExpr::getBitCast(GV, i8PTy); 330 asmUsed2.push_back(c); 331 } 332 333 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size()); 334 LLVMCompilerUsed = 335 new llvm::GlobalVariable(*mergedModule, ATy, false, 336 llvm::GlobalValue::AppendingLinkage, 337 llvm::ConstantArray::get(ATy, asmUsed2), 338 "llvm.compiler.used"); 339 340 LLVMCompilerUsed->setSection("llvm.metadata"); 341 342 passes.add(createInternalizePass(mustPreserveList)); 343 344 // apply scope restrictions 345 passes.doInitialization(); 346 passes.run(*mergedModule); 347 passes.doFinalization(); 348 349 _scopeRestrictionsDone = true; 350} 351 352/// Optimize merged modules using various IPO passes 353bool LTOCodeGenerator::generateObjectFile(raw_ostream &out, 354 std::string &errMsg) { 355 if (this->determineTarget(errMsg)) 356 return true; 357 358 Module* mergedModule = _linker.getModule(); 359 360 // if options were requested, set them 361 if (!_codegenOptions.empty()) 362 cl::ParseCommandLineOptions(_codegenOptions.size(), 363 const_cast<char **>(&_codegenOptions[0])); 364 365 // mark which symbols can not be internalized 366 this->applyScopeRestrictions(); 367 368 // Instantiate the pass manager to organize the passes. 369 PassManager passes; 370 371 // Start off with a verification pass. 372 passes.add(createVerifierPass()); 373 374 // Add an appropriate DataLayout instance for this module... 375 passes.add(new DataLayout(*_target->getDataLayout())); 376 passes.add(new TargetTransformInfo(_target->getScalarTargetTransformInfo(), 377 _target->getVectorTargetTransformInfo())); 378 379 // Enabling internalize here would use its AllButMain variant. It 380 // keeps only main if it exists and does nothing for libraries. Instead 381 // we create the pass ourselves with the symbol list provided by the linker. 382 PassManagerBuilder().populateLTOPassManager(passes, /*Internalize=*/false, 383 !DisableInline, 384 DisableGVNLoadPRE); 385 386 // Make sure everything is still good. 387 passes.add(createVerifierPass()); 388 389 FunctionPassManager *codeGenPasses = new FunctionPassManager(mergedModule); 390 391 codeGenPasses->add(new DataLayout(*_target->getDataLayout())); 392 393 formatted_raw_ostream Out(out); 394 395 if (_target->addPassesToEmitFile(*codeGenPasses, Out, 396 TargetMachine::CGFT_ObjectFile)) { 397 errMsg = "target file type not supported"; 398 return true; 399 } 400 401 // Run our queue of passes all at once now, efficiently. 402 passes.doInitialization(); 403 passes.run(*mergedModule); 404 passes.doFinalization(); 405 406 // Run the code generator, and write assembly file 407 codeGenPasses->doInitialization(); 408 409 for (Module::iterator 410 it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it) 411 if (!it->isDeclaration()) 412 codeGenPasses->run(*it); 413 414 codeGenPasses->doFinalization(); 415 delete codeGenPasses; 416 417 return false; // success 418} 419 420/// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging 421/// LTO problems. 422void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) { 423 for (std::pair<StringRef, StringRef> o = getToken(options); 424 !o.first.empty(); o = getToken(o.second)) { 425 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add 426 // that. 427 if (_codegenOptions.empty()) 428 _codegenOptions.push_back(strdup("libLTO")); 429 _codegenOptions.push_back(strdup(o.first.str().c_str())); 430 } 431} 432