tools/lto/LTOCodeGenerator.cpp

   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
  18
  19 #include "llvm/Constants.h"
  20 #include "llvm/DerivedTypes.h"
  21 #include "llvm/Linker.h"
  22 #include "llvm/Module.h"
  23 #include "llvm/ModuleProvider.h"
  24 #include "llvm/PassManager.h"
  25 #include "llvm/ADT/StringExtras.h"
  26 #include "llvm/Analysis/Passes.h"
  27 #include "llvm/Analysis/LoopPass.h"
  28 #include "llvm/Analysis/Verifier.h"
  29 #include "llvm/Bitcode/ReaderWriter.h"
  30 #include "llvm/CodeGen/FileWriters.h"
  31 #include "llvm/Support/CommandLine.h"
  32 #include "llvm/Support/Mangler.h"
  33 #include "llvm/Support/MemoryBuffer.h"
  34 #include "llvm/Support/StandardPasses.h"
  35 #include "llvm/Support/SystemUtils.h"
  36 #include "llvm/Support/raw_ostream.h"
  37 #include "llvm/System/Signals.h"
  38 #include "llvm/Target/SubtargetFeature.h"
  39 #include "llvm/Target/TargetOptions.h"
  40 #include "llvm/Target/TargetAsmInfo.h"
  41 #include "llvm/Target/TargetData.h"
  42 #include "llvm/Target/TargetMachine.h"
  43 #include "llvm/Target/TargetMachineRegistry.h"
  44 #include "llvm/Target/TargetSelect.h"
  45 #include "llvm/Transforms/IPO.h"
  46 #include "llvm/Transforms/Scalar.h"
  47 #include "llvm/Config/config.h"
  48
  49
  50 #include <cstdlib>
  51 #include <fstream>
  52 #include <unistd.h>
  53 #include <fcntl.h>
  54
  55
  56 using namespace llvm;
  57
  58 static cl::opt<bool> DisableInline("disable-inlining",
  59   cl::desc("Do not run the inliner pass"));
  60
  61
  62 const char* LTOCodeGenerator::getVersionString()
  63 {
  64 #ifdef LLVM_VERSION_INFO
  65     return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
  66 #else
  67     return PACKAGE_NAME " version " PACKAGE_VERSION;
  68 #endif
  69 }
  70
  71
  72 LTOCodeGenerator::LTOCodeGenerator(const LLVMContext& Context)
  73     : _context(Context),
  74       _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
  75       _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
  76       _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
  77       _nativeObjectFile(NULL), _gccPath(NULL), _assemblerPath(NULL)
  78 {
  79   InitializeAllTargets();
  80   InitializeAllAsmPrinters();
  81
  82 }
  83
  84 LTOCodeGenerator::~LTOCodeGenerator()
  85 {
  86     delete _target;
  87     delete _nativeObjectFile;
  88 }
  89
  90
  91
  92 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg)
  93 {
  94     return _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
  95 }
  96
  97
  98 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg)
  99 {
 100     switch (debug) {
 101         case LTO_DEBUG_MODEL_NONE:
 102             _emitDwarfDebugInfo = false;
 103             return false;
 104
 105         case LTO_DEBUG_MODEL_DWARF:
 106             _emitDwarfDebugInfo = true;
 107             return false;
 108     }
 109     errMsg = "unknown debug format";
 110     return true;
 111 }
 112
 113
 114 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
 115                                        std::string& errMsg)
 116 {
 117     switch (model) {
 118         case LTO_CODEGEN_PIC_MODEL_STATIC:
 119         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 120         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 121             _codeModel = model;
 122             return false;
 123     }
 124     errMsg = "unknown pic model";
 125     return true;
 126 }
 127
 128 void LTOCodeGenerator::setGccPath(const char* path)
 129 {
 130     if ( _gccPath )
 131         delete _gccPath;
 132     _gccPath = new sys::Path(path);
 133 }
 134
 135 void LTOCodeGenerator::setAssemblerPath(const char* path)
 136 {
 137     if ( _assemblerPath )
 138         delete _assemblerPath;
 139     _assemblerPath = new sys::Path(path);
 140 }
 141
 142 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
 143 {
 144     _mustPreserveSymbols[sym] = 1;
 145 }
 146
 147
 148 bool LTOCodeGenerator::writeMergedModules(const char* path, std::string& errMsg)
 149 {
 150     if ( this->determineTarget(errMsg) )
 151         return true;
 152
 153     // mark which symbols can not be internalized
 154     this->applyScopeRestrictions();
 155
 156     // create output file
 157     std::ofstream out(path, std::ios_base::out|std::ios::trunc|std::ios::binary);
 158     if ( out.fail() ) {
 159         errMsg = "could not open bitcode file for writing: ";
 160         errMsg += path;
 161         return true;
 162     }
 163
 164     // write bitcode to it
 165     WriteBitcodeToFile(_linker.getModule(), out);
 166     if ( out.fail() ) {
 167         errMsg = "could not write bitcode file: ";
 168         errMsg += path;
 169         return true;
 170     }
 171
 172     return false;
 173 }
 174
 175
 176 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
 177 {
 178     // make unique temp .s file to put generated assembly code
 179     sys::Path uniqueAsmPath("lto-llvm.s");
 180     if ( uniqueAsmPath.createTemporaryFileOnDisk(true, &errMsg) )
 181         return NULL;
 182     sys::RemoveFileOnSignal(uniqueAsmPath);
 183
 184     // generate assembly code
 185     bool genResult = false;
 186     {
 187       raw_fd_ostream asmFile(uniqueAsmPath.c_str(), false, errMsg);
 188       if (!errMsg.empty())
 189         return NULL;
 190       genResult = this->generateAssemblyCode(asmFile, errMsg);
 191     }
 192     if ( genResult ) {
 193         if ( uniqueAsmPath.exists() )
 194             uniqueAsmPath.eraseFromDisk();
 195         return NULL;
 196     }
 197
 198     // make unique temp .o file to put generated object file
 199     sys::PathWithStatus uniqueObjPath("lto-llvm.o");
 200     if ( uniqueObjPath.createTemporaryFileOnDisk(true, &errMsg) ) {
 201         if ( uniqueAsmPath.exists() )
 202             uniqueAsmPath.eraseFromDisk();
 203         return NULL;
 204     }
 205     sys::RemoveFileOnSignal(uniqueObjPath);
 206
 207     // assemble the assembly code
 208     const std::string& uniqueObjStr = uniqueObjPath.toString();
 209     bool asmResult = this->assemble(uniqueAsmPath.toString(),
 210                                                         uniqueObjStr, errMsg);
 211     if ( !asmResult ) {
 212         // remove old buffer if compile() called twice
 213         delete _nativeObjectFile;
 214
 215         // read .o file into memory buffer
 216         _nativeObjectFile = MemoryBuffer::getFile(uniqueObjStr.c_str(),&errMsg);
 217     }
 218
 219     // remove temp files
 220     uniqueAsmPath.eraseFromDisk();
 221     uniqueObjPath.eraseFromDisk();
 222
 223     // return buffer, unless error
 224     if ( _nativeObjectFile == NULL )
 225         return NULL;
 226     *length = _nativeObjectFile->getBufferSize();
 227     return _nativeObjectFile->getBufferStart();
 228 }
 229
 230
 231 bool LTOCodeGenerator::assemble(const std::string& asmPath,
 232                                 const std::string& objPath, std::string& errMsg)
 233 {
 234     sys::Path tool;
 235     bool needsCompilerOptions = true;
 236     if ( _assemblerPath ) {
 237         tool = *_assemblerPath;
 238         needsCompilerOptions = false;
 239     }
 240     else if ( _gccPath ) {
 241         tool = *_gccPath;
 242     } else {
 243         // find compiler driver
 244         tool = sys::Program::FindProgramByName("gcc");
 245         if ( tool.isEmpty() ) {
 246             errMsg = "can't locate gcc";
 247             return true;
 248         }
 249     }
 250
 251     // build argument list
 252     std::vector<const char*> args;
 253     std::string targetTriple = _linker.getModule()->getTargetTriple();
 254     args.push_back(tool.c_str());
 255     if ( targetTriple.find("darwin") != std::string::npos ) {
 256         // darwin specific command line options
 257         if (strncmp(targetTriple.c_str(), "i386-apple-", 11) == 0) {
 258             args.push_back("-arch");
 259             args.push_back("i386");
 260         }
 261         else if (strncmp(targetTriple.c_str(), "x86_64-apple-", 13) == 0) {
 262             args.push_back("-arch");
 263             args.push_back("x86_64");
 264         }
 265         else if (strncmp(targetTriple.c_str(), "powerpc-apple-", 14) == 0) {
 266             args.push_back("-arch");
 267             args.push_back("ppc");
 268         }
 269         else if (strncmp(targetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
 270             args.push_back("-arch");
 271             args.push_back("ppc64");
 272         }
 273         else if (strncmp(targetTriple.c_str(), "arm-apple-", 10) == 0) {
 274             args.push_back("-arch");
 275             args.push_back("arm");
 276         }
 277         else if ((strncmp(targetTriple.c_str(), "armv4t-apple-", 13) == 0) ||
 278                  (strncmp(targetTriple.c_str(), "thumbv4t-apple-", 15) == 0)) {
 279             args.push_back("-arch");
 280             args.push_back("armv4t");
 281         }
 282         else if ((strncmp(targetTriple.c_str(), "armv5-apple-", 12) == 0) ||
 283                  (strncmp(targetTriple.c_str(), "armv5e-apple-", 13) == 0) ||
 284                  (strncmp(targetTriple.c_str(), "thumbv5-apple-", 14) == 0) ||
 285                  (strncmp(targetTriple.c_str(), "thumbv5e-apple-", 15) == 0)) {
 286             args.push_back("-arch");
 287             args.push_back("armv5");
 288         }
 289         else if ((strncmp(targetTriple.c_str(), "armv6-apple-", 12) == 0) ||
 290                  (strncmp(targetTriple.c_str(), "thumbv6-apple-", 14) == 0)) {
 291             args.push_back("-arch");
 292             args.push_back("armv6");
 293         }
 294         else if ((strncmp(targetTriple.c_str(), "armv7-apple-", 12) == 0) ||
 295                  (strncmp(targetTriple.c_str(), "thumbv7-apple-", 14) == 0)) {
 296             args.push_back("-arch");
 297             args.push_back("armv7");
 298         }
 299         // add -static to assembler command line when code model requires
 300         if ( (_assemblerPath != NULL) && (_codeModel == LTO_CODEGEN_PIC_MODEL_STATIC) )
 301             args.push_back("-static");
 302     }
 303     if ( needsCompilerOptions ) {
 304         args.push_back("-c");
 305         args.push_back("-x");
 306         args.push_back("assembler");
 307     }
 308     args.push_back("-o");
 309     args.push_back(objPath.c_str());
 310     args.push_back(asmPath.c_str());
 311     args.push_back(0);
 312
 313     // invoke assembler
 314     if ( sys::Program::ExecuteAndWait(tool, &args[0], 0, 0, 0, 0, &errMsg) ) {
 315         errMsg = "error in assembly";
 316         return true;
 317     }
 318     return false; // success
 319 }
 320
 321
 322
 323 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
 324 {
 325     if ( _target == NULL ) {
 326         // create target machine from info for merged modules
 327         Module* mergedModule = _linker.getModule();
 328         const TargetMachineRegistry::entry* march =
 329           TargetMachineRegistry::getClosestStaticTargetForModule(
 330                                                        *mergedModule, errMsg);
 331         if ( march == NULL )
 332             return true;
 333
 334         // The relocation model is actually a static member of TargetMachine
 335         // and needs to be set before the TargetMachine is instantiated.
 336         switch( _codeModel ) {
 337         case LTO_CODEGEN_PIC_MODEL_STATIC:
 338             TargetMachine::setRelocationModel(Reloc::Static);
 339             break;
 340         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 341             TargetMachine::setRelocationModel(Reloc::PIC_);
 342             break;
 343         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 344             TargetMachine::setRelocationModel(Reloc::DynamicNoPIC);
 345             break;
 346         }
 347
 348         // construct LTModule, hand over ownership of module and target
 349         std::string FeatureStr =
 350           getFeatureString(_linker.getModule()->getTargetTriple().c_str());
 351         _target = march->CtorFn(*mergedModule, FeatureStr.c_str());
 352     }
 353     return false;
 354 }
 355
 356 void LTOCodeGenerator::applyScopeRestrictions()
 357 {
 358     if ( !_scopeRestrictionsDone ) {
 359         Module* mergedModule = _linker.getModule();
 360
 361         // Start off with a verification pass.
 362         PassManager passes;
 363         passes.add(createVerifierPass());
 364
 365         // mark which symbols can not be internalized
 366         if ( !_mustPreserveSymbols.empty() ) {
 367             Mangler mangler(*mergedModule,
 368                                 _target->getTargetAsmInfo()->getGlobalPrefix());
 369             std::vector<const char*> mustPreserveList;
 370             for (Module::iterator f = mergedModule->begin(),
 371                                         e = mergedModule->end(); f != e; ++f) {
 372                 if ( !f->isDeclaration()
 373                   && _mustPreserveSymbols.count(mangler.getValueName(f)) )
 374                     mustPreserveList.push_back(::strdup(f->getName().c_str()));
 375             }
 376             for (Module::global_iterator v = mergedModule->global_begin(),
 377                                  e = mergedModule->global_end(); v !=  e; ++v) {
 378                 if ( !v->isDeclaration()
 379                   && _mustPreserveSymbols.count(mangler.getValueName(v)) )
 380                     mustPreserveList.push_back(::strdup(v->getName().c_str()));
 381             }
 382             passes.add(createInternalizePass(mustPreserveList));
 383         }
 384         // apply scope restrictions
 385         passes.run(*mergedModule);
 386
 387         _scopeRestrictionsDone = true;
 388     }
 389 }
 390
 391 /// Optimize merged modules using various IPO passes
 392 bool LTOCodeGenerator::generateAssemblyCode(raw_ostream& out,
 393                                             std::string& errMsg)
 394 {
 395     if (  this->determineTarget(errMsg) )
 396         return true;
 397
 398     // mark which symbols can not be internalized
 399     this->applyScopeRestrictions();
 400
 401     Module* mergedModule = _linker.getModule();
 402
 403      // If target supports exception handling then enable it now.
 404     if ( _target->getTargetAsmInfo()->doesSupportExceptionHandling() )
 405         llvm::ExceptionHandling = true;
 406
 407     // if options were requested, set them
 408     if ( !_codegenOptions.empty() )
 409         cl::ParseCommandLineOptions(_codegenOptions.size(),
 410                                                 (char**)&_codegenOptions[0]);
 411
 412     // Instantiate the pass manager to organize the passes.
 413     PassManager passes;
 414
 415     // Start off with a verification pass.
 416     passes.add(createVerifierPass());
 417
 418     // Add an appropriate TargetData instance for this module...
 419     passes.add(new TargetData(*_target->getTargetData()));
 420
 421     createStandardLTOPasses(&passes, /*Internalize=*/ false, !DisableInline,
 422                             /*VerifyEach=*/ false);
 423
 424     // Make sure everything is still good.
 425     passes.add(createVerifierPass());
 426
 427     FunctionPassManager* codeGenPasses =
 428             new FunctionPassManager(new ExistingModuleProvider(mergedModule));
 429
 430     codeGenPasses->add(new TargetData(*_target->getTargetData()));
 431
 432     MachineCodeEmitter* mce = NULL;
 433
 434     switch (_target->addPassesToEmitFile(*codeGenPasses, out,
 435                                          TargetMachine::AssemblyFile,
 436                                          CodeGenOpt::Aggressive)) {
 437         case FileModel::MachOFile:
 438             mce = AddMachOWriter(*codeGenPasses, out, *_target);
 439             break;
 440         case FileModel::ElfFile:
 441             mce = AddELFWriter(*codeGenPasses, out, *_target);
 442             break;
 443         case FileModel::AsmFile:
 444             break;
 445         case FileModel::Error:
 446         case FileModel::None:
 447             errMsg = "target file type not supported";
 448             return true;
 449     }
 450
 451     if (_target->addPassesToEmitFileFinish(*codeGenPasses, mce,
 452                                            CodeGenOpt::Aggressive)) {
 453         errMsg = "target does not support generation of this file type";
 454         return true;
 455     }
 456
 457     // Run our queue of passes all at once now, efficiently.
 458     passes.run(*mergedModule);
 459
 460     // Run the code generator, and write assembly file
 461     codeGenPasses->doInitialization();
 462
 463     for (Module::iterator
 464            it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
 465       if (!it->isDeclaration())
 466         codeGenPasses->run(*it);
 467
 468     codeGenPasses->doFinalization();
 469     return false; // success
 470 }
 471
 472
 473 /// Optimize merged modules using various IPO passes
 474 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
 475 {
 476     std::string ops(options);
 477     for (std::string o = getToken(ops); !o.empty(); o = getToken(ops)) {
 478         // ParseCommandLineOptions() expects argv[0] to be program name.
 479         // Lazily add that.
 480         if ( _codegenOptions.empty() )
 481             _codegenOptions.push_back("libLTO");
 482         _codegenOptions.push_back(strdup(o.c_str()));
 483     }
 484 }