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 #include "llvm/Constants.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/ADT/StringExtras.h"
  25 #include "llvm/ADT/Triple.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/Support/CommandLine.h"
  31 #include "llvm/Support/FormattedStream.h"
  32 #include "llvm/Support/MemoryBuffer.h"
  33 #include "llvm/Support/StandardPasses.h"
  34 #include "llvm/Support/SystemUtils.h"
  35 #include "llvm/System/Host.h"
  36 #include "llvm/System/Program.h"
  37 #include "llvm/System/Signals.h"
  38 #include "llvm/Target/Mangler.h"
  39 #include "llvm/Target/SubtargetFeature.h"
  40 #include "llvm/Target/TargetOptions.h"
  41 #include "llvm/MC/MCAsmInfo.h"
  42 #include "llvm/Target/TargetData.h"
  43 #include "llvm/Target/TargetMachine.h"
  44 #include "llvm/Target/TargetRegistry.h"
  45 #include "llvm/Target/TargetSelect.h"
  46 #include "llvm/Transforms/IPO.h"
  47 #include "llvm/Transforms/Scalar.h"
  48 #include "llvm/Config/config.h"
  49 #include <cstdlib>
  50 #include <unistd.h>
  51 #include <fcntl.h>
  52
  53
  54 using namespace llvm;
  55
  56 static cl::opt<bool> DisableInline("disable-inlining",
  57   cl::desc("Do not run the inliner pass"));
  58
  59
  60 const char* LTOCodeGenerator::getVersionString()
  61 {
  62 #ifdef LLVM_VERSION_INFO
  63     return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
  64 #else
  65     return PACKAGE_NAME " version " PACKAGE_VERSION;
  66 #endif
  67 }
  68
  69
  70 LTOCodeGenerator::LTOCodeGenerator()
  71     : _context(getGlobalContext()),
  72       _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
  73       _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
  74       _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
  75       _nativeObjectFile(NULL), _assemblerPath(NULL)
  76 {
  77     InitializeAllTargets();
  78     InitializeAllAsmPrinters();
  79 }
  80
  81 LTOCodeGenerator::~LTOCodeGenerator()
  82 {
  83     delete _target;
  84     delete _nativeObjectFile;
  85 }
  86
  87
  88
  89 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg)
  90 {
  91     return _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
  92 }
  93
  94
  95 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg)
  96 {
  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     errMsg = "unknown debug format";
 107     return true;
 108 }
 109
 110
 111 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
 112                                        std::string& errMsg)
 113 {
 114     switch (model) {
 115         case LTO_CODEGEN_PIC_MODEL_STATIC:
 116         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 117         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 118             _codeModel = model;
 119             return false;
 120     }
 121     errMsg = "unknown pic model";
 122     return true;
 123 }
 124
 125 void LTOCodeGenerator::setAssemblerPath(const char* path)
 126 {
 127     if ( _assemblerPath )
 128         delete _assemblerPath;
 129     _assemblerPath = new sys::Path(path);
 130 }
 131
 132 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
 133 {
 134     _mustPreserveSymbols[sym] = 1;
 135 }
 136
 137
 138 bool LTOCodeGenerator::writeMergedModules(const char *path,
 139                                           std::string &errMsg) {
 140   if (determineTarget(errMsg))
 141     return true;
 142
 143   // mark which symbols can not be internalized
 144   applyScopeRestrictions();
 145
 146   // create output file
 147   std::string ErrInfo;
 148   raw_fd_ostream Out(path, ErrInfo,
 149                      raw_fd_ostream::F_Binary);
 150   if (!ErrInfo.empty()) {
 151     errMsg = "could not open bitcode file for writing: ";
 152     errMsg += path;
 153     return true;
 154   }
 155
 156   // write bitcode to it
 157   WriteBitcodeToFile(_linker.getModule(), Out);
 158
 159   if (Out.has_error()) {
 160     errMsg = "could not write bitcode file: ";
 161     errMsg += path;
 162     return true;
 163   }
 164
 165   return false;
 166 }
 167
 168
 169 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
 170 {
 171     // make unique temp .s file to put generated assembly code
 172     sys::Path uniqueAsmPath("lto-llvm.s");
 173     if ( uniqueAsmPath.createTemporaryFileOnDisk(true, &errMsg) )
 174         return NULL;
 175     sys::RemoveFileOnSignal(uniqueAsmPath);
 176
 177     // generate assembly code
 178     bool genResult = false;
 179     {
 180       raw_fd_ostream asmFD(uniqueAsmPath.c_str(), errMsg);
 181       formatted_raw_ostream asmFile(asmFD);
 182       if (!errMsg.empty())
 183         return NULL;
 184       genResult = this->generateAssemblyCode(asmFile, errMsg);
 185     }
 186     if ( genResult ) {
 187         if ( uniqueAsmPath.exists() )
 188             uniqueAsmPath.eraseFromDisk();
 189         return NULL;
 190     }
 191
 192     // make unique temp .o file to put generated object file
 193     sys::PathWithStatus uniqueObjPath("lto-llvm.o");
 194     if ( uniqueObjPath.createTemporaryFileOnDisk(true, &errMsg) ) {
 195         if ( uniqueAsmPath.exists() )
 196             uniqueAsmPath.eraseFromDisk();
 197         return NULL;
 198     }
 199     sys::RemoveFileOnSignal(uniqueObjPath);
 200
 201     // assemble the assembly code
 202     const std::string& uniqueObjStr = uniqueObjPath.str();
 203     bool asmResult = this->assemble(uniqueAsmPath.str(), uniqueObjStr, errMsg);
 204     if ( !asmResult ) {
 205         // remove old buffer if compile() called twice
 206         delete _nativeObjectFile;
 207
 208         // read .o file into memory buffer
 209         _nativeObjectFile = MemoryBuffer::getFile(uniqueObjStr.c_str(),&errMsg);
 210     }
 211
 212     // remove temp files
 213     uniqueAsmPath.eraseFromDisk();
 214     uniqueObjPath.eraseFromDisk();
 215
 216     // return buffer, unless error
 217     if ( _nativeObjectFile == NULL )
 218         return NULL;
 219     *length = _nativeObjectFile->getBufferSize();
 220     return _nativeObjectFile->getBufferStart();
 221 }
 222
 223
 224 bool LTOCodeGenerator::assemble(const std::string& asmPath,
 225                                 const std::string& objPath, std::string& errMsg)
 226 {
 227     sys::Path tool;
 228     bool needsCompilerOptions = true;
 229     if ( _assemblerPath ) {
 230         tool = *_assemblerPath;
 231         needsCompilerOptions = false;
 232     } else {
 233         // find compiler driver
 234         tool = sys::Program::FindProgramByName("gcc");
 235         if ( tool.isEmpty() ) {
 236             errMsg = "can't locate gcc";
 237             return true;
 238         }
 239     }
 240
 241     // build argument list
 242     std::vector<const char*> args;
 243     llvm::Triple targetTriple(_linker.getModule()->getTargetTriple());
 244     const char *arch = targetTriple.getArchNameForAssembler();
 245
 246     args.push_back(tool.c_str());
 247
 248     if (targetTriple.getOS() == Triple::Darwin) {
 249         // darwin specific command line options
 250         if (arch != NULL) {
 251             args.push_back("-arch");
 252             args.push_back(arch);
 253         }
 254         // add -static to assembler command line when code model requires
 255         if ( (_assemblerPath != NULL) && (_codeModel == LTO_CODEGEN_PIC_MODEL_STATIC) )
 256             args.push_back("-static");
 257     }
 258     if ( needsCompilerOptions ) {
 259         args.push_back("-c");
 260         args.push_back("-x");
 261         args.push_back("assembler");
 262     }
 263     args.push_back("-o");
 264     args.push_back(objPath.c_str());
 265     args.push_back(asmPath.c_str());
 266     args.push_back(0);
 267
 268     // invoke assembler
 269     if ( sys::Program::ExecuteAndWait(tool, &args[0], 0, 0, 0, 0, &errMsg) ) {
 270         errMsg = "error in assembly";
 271         return true;
 272     }
 273     return false; // success
 274 }
 275
 276
 277
 278 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
 279 {
 280     if ( _target == NULL ) {
 281         std::string Triple = _linker.getModule()->getTargetTriple();
 282         if (Triple.empty())
 283           Triple = sys::getHostTriple();
 284
 285         // create target machine from info for merged modules
 286         const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
 287         if ( march == NULL )
 288             return true;
 289
 290         // The relocation model is actually a static member of TargetMachine
 291         // and needs to be set before the TargetMachine is instantiated.
 292         switch( _codeModel ) {
 293         case LTO_CODEGEN_PIC_MODEL_STATIC:
 294             TargetMachine::setRelocationModel(Reloc::Static);
 295             break;
 296         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 297             TargetMachine::setRelocationModel(Reloc::PIC_);
 298             break;
 299         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 300             TargetMachine::setRelocationModel(Reloc::DynamicNoPIC);
 301             break;
 302         }
 303
 304         // construct LTModule, hand over ownership of module and target
 305         const std::string FeatureStr =
 306             SubtargetFeatures::getDefaultSubtargetFeatures(llvm::Triple(Triple));
 307         _target = march->createTargetMachine(Triple, FeatureStr);
 308     }
 309     return false;
 310 }
 311
 312 void LTOCodeGenerator::applyScopeRestrictions()
 313 {
 314     if ( !_scopeRestrictionsDone ) {
 315         Module* mergedModule = _linker.getModule();
 316
 317         // Start off with a verification pass.
 318         PassManager passes;
 319         passes.add(createVerifierPass());
 320
 321         // mark which symbols can not be internalized
 322         if ( !_mustPreserveSymbols.empty() ) {
 323             Mangler mangler(*_target->getMCAsmInfo());
 324             std::vector<const char*> mustPreserveList;
 325             for (Module::iterator f = mergedModule->begin(),
 326                                         e = mergedModule->end(); f != e; ++f) {
 327                 if ( !f->isDeclaration()
 328                   && _mustPreserveSymbols.count(mangler.getNameWithPrefix(f)) )
 329                   mustPreserveList.push_back(::strdup(f->getNameStr().c_str()));
 330             }
 331             for (Module::global_iterator v = mergedModule->global_begin(),
 332                                  e = mergedModule->global_end(); v !=  e; ++v) {
 333                 if ( !v->isDeclaration()
 334                   && _mustPreserveSymbols.count(mangler.getNameWithPrefix(v)) )
 335                   mustPreserveList.push_back(::strdup(v->getNameStr().c_str()));
 336             }
 337             passes.add(createInternalizePass(mustPreserveList));
 338         }
 339         // apply scope restrictions
 340         passes.run(*mergedModule);
 341
 342         _scopeRestrictionsDone = true;
 343     }
 344 }
 345
 346 /// Optimize merged modules using various IPO passes
 347 bool LTOCodeGenerator::generateAssemblyCode(formatted_raw_ostream& out,
 348                                             std::string& errMsg)
 349 {
 350     if ( this->determineTarget(errMsg) )
 351         return true;
 352
 353     // mark which symbols can not be internalized
 354     this->applyScopeRestrictions();
 355
 356     Module* mergedModule = _linker.getModule();
 357
 358     // If target supports exception handling then enable it now.
 359     switch (_target->getMCAsmInfo()->getExceptionHandlingType()) {
 360     case ExceptionHandling::Dwarf:
 361       llvm::DwarfExceptionHandling = true;
 362       break;
 363     case ExceptionHandling::SjLj:
 364       llvm::SjLjExceptionHandling = true;
 365       break;
 366     case ExceptionHandling::None:
 367       break;
 368     default:
 369       assert (0 && "Unknown exception handling model!");
 370     }
 371
 372     // if options were requested, set them
 373     if ( !_codegenOptions.empty() )
 374         cl::ParseCommandLineOptions(_codegenOptions.size(),
 375                                                 (char**)&_codegenOptions[0]);
 376
 377     // Instantiate the pass manager to organize the passes.
 378     PassManager passes;
 379
 380     // Start off with a verification pass.
 381     passes.add(createVerifierPass());
 382
 383     // Add an appropriate TargetData instance for this module...
 384     passes.add(new TargetData(*_target->getTargetData()));
 385
 386     createStandardLTOPasses(&passes, /*Internalize=*/ false, !DisableInline,
 387                             /*VerifyEach=*/ false);
 388
 389     // Make sure everything is still good.
 390     passes.add(createVerifierPass());
 391
 392     FunctionPassManager* codeGenPasses = new FunctionPassManager(mergedModule);
 393
 394     codeGenPasses->add(new TargetData(*_target->getTargetData()));
 395
 396     if (_target->addPassesToEmitFile(*codeGenPasses, out,
 397                                      TargetMachine::CGFT_AssemblyFile,
 398                                      CodeGenOpt::Aggressive)) {
 399       errMsg = "target file type not supported";
 400       return true;
 401     }
 402
 403     // Run our queue of passes all at once now, efficiently.
 404     passes.run(*mergedModule);
 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
 416     return false; // success
 417 }
 418
 419
 420 /// Optimize merged modules using various IPO passes
 421 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
 422 {
 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.
 426         // Lazily add that.
 427         if ( _codegenOptions.empty() )
 428             _codegenOptions.push_back("libLTO");
 429         _codegenOptions.push_back(strdup(o.first.str().c_str()));
 430     }
 431 }