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/LLVMContext.h"
  23 #include "llvm/Module.h"
  24 #include "llvm/ModuleProvider.h"
  25 #include "llvm/PassManager.h"
  26 #include "llvm/ADT/StringExtras.h"
  27 #include "llvm/ADT/Triple.h"
  28 #include "llvm/Analysis/Passes.h"
  29 #include "llvm/Analysis/LoopPass.h"
  30 #include "llvm/Analysis/Verifier.h"
  31 #include "llvm/Bitcode/ReaderWriter.h"
  32 #include "llvm/CodeGen/FileWriters.h"
  33 #include "llvm/Support/CommandLine.h"
  34 #include "llvm/Support/FormattedStream.h"
  35 #include "llvm/Support/Mangler.h"
  36 #include "llvm/Support/MemoryBuffer.h"
  37 #include "llvm/Support/StandardPasses.h"
  38 #include "llvm/Support/SystemUtils.h"
  39 #include "llvm/System/Host.h"
  40 #include "llvm/System/Program.h"
  41 #include "llvm/System/Signals.h"
  42 #include "llvm/Target/SubtargetFeature.h"
  43 #include "llvm/Target/TargetOptions.h"
  44 #include "llvm/MC/MCAsmInfo.h"
  45 #include "llvm/Target/TargetData.h"
  46 #include "llvm/Target/TargetMachine.h"
  47 #include "llvm/Target/TargetRegistry.h"
  48 #include "llvm/Target/TargetSelect.h"
  49 #include "llvm/Transforms/IPO.h"
  50 #include "llvm/Transforms/Scalar.h"
  51 #include "llvm/Config/config.h"
  52 #include <cstdlib>
  53 #include <unistd.h>
  54 #include <fcntl.h>
  55
  56
  57 using namespace llvm;
  58
  59 static cl::opt<bool> DisableInline("disable-inlining",
  60   cl::desc("Do not run the inliner pass"));
  61
  62
  63 const char* LTOCodeGenerator::getVersionString()
  64 {
  65 #ifdef LLVM_VERSION_INFO
  66     return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
  67 #else
  68     return PACKAGE_NAME " version " PACKAGE_VERSION;
  69 #endif
  70 }
  71
  72
  73 LTOCodeGenerator::LTOCodeGenerator()
  74     : _context(getGlobalContext()),
  75       _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
  76       _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
  77       _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
  78       _nativeObjectFile(NULL), _assemblerPath(NULL)
  79 {
  80     InitializeAllTargets();
  81     InitializeAllAsmPrinters();
  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::setAssemblerPath(const char* path)
 129 {
 130     if ( _assemblerPath )
 131         delete _assemblerPath;
 132     _assemblerPath = new sys::Path(path);
 133 }
 134
 135 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
 136 {
 137     _mustPreserveSymbols[sym] = 1;
 138 }
 139
 140
 141 bool LTOCodeGenerator::writeMergedModules(const char *path,
 142                                           std::string &errMsg) {
 143   if (determineTarget(errMsg))
 144     return true;
 145
 146   // mark which symbols can not be internalized
 147   applyScopeRestrictions();
 148
 149   // create output file
 150   std::string ErrInfo;
 151   raw_fd_ostream Out(path, ErrInfo,
 152                      raw_fd_ostream::F_Binary);
 153   if (!ErrInfo.empty()) {
 154     errMsg = "could not open bitcode file for writing: ";
 155     errMsg += path;
 156     return true;
 157   }
 158
 159   // write bitcode to it
 160   WriteBitcodeToFile(_linker.getModule(), Out);
 161
 162   if (Out.has_error()) {
 163     errMsg = "could not write bitcode file: ";
 164     errMsg += path;
 165     return true;
 166   }
 167
 168   return false;
 169 }
 170
 171
 172 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
 173 {
 174     // make unique temp .s file to put generated assembly code
 175     sys::Path uniqueAsmPath("lto-llvm.s");
 176     if ( uniqueAsmPath.createTemporaryFileOnDisk(true, &errMsg) )
 177         return NULL;
 178     sys::RemoveFileOnSignal(uniqueAsmPath);
 179
 180     // generate assembly code
 181     bool genResult = false;
 182     {
 183       raw_fd_ostream asmFD(uniqueAsmPath.c_str(), errMsg);
 184       formatted_raw_ostream asmFile(asmFD);
 185       if (!errMsg.empty())
 186         return NULL;
 187       genResult = this->generateAssemblyCode(asmFile, errMsg);
 188     }
 189     if ( genResult ) {
 190         if ( uniqueAsmPath.exists() )
 191             uniqueAsmPath.eraseFromDisk();
 192         return NULL;
 193     }
 194
 195     // make unique temp .o file to put generated object file
 196     sys::PathWithStatus uniqueObjPath("lto-llvm.o");
 197     if ( uniqueObjPath.createTemporaryFileOnDisk(true, &errMsg) ) {
 198         if ( uniqueAsmPath.exists() )
 199             uniqueAsmPath.eraseFromDisk();
 200         return NULL;
 201     }
 202     sys::RemoveFileOnSignal(uniqueObjPath);
 203
 204     // assemble the assembly code
 205     const std::string& uniqueObjStr = uniqueObjPath.str();
 206     bool asmResult = this->assemble(uniqueAsmPath.str(), uniqueObjStr, errMsg);
 207     if ( !asmResult ) {
 208         // remove old buffer if compile() called twice
 209         delete _nativeObjectFile;
 210
 211         // read .o file into memory buffer
 212         _nativeObjectFile = MemoryBuffer::getFile(uniqueObjStr.c_str(),&errMsg);
 213     }
 214
 215     // remove temp files
 216     uniqueAsmPath.eraseFromDisk();
 217     uniqueObjPath.eraseFromDisk();
 218
 219     // return buffer, unless error
 220     if ( _nativeObjectFile == NULL )
 221         return NULL;
 222     *length = _nativeObjectFile->getBufferSize();
 223     return _nativeObjectFile->getBufferStart();
 224 }
 225
 226
 227 bool LTOCodeGenerator::assemble(const std::string& asmPath,
 228                                 const std::string& objPath, std::string& errMsg)
 229 {
 230     sys::Path tool;
 231     bool needsCompilerOptions = true;
 232     if ( _assemblerPath ) {
 233         tool = *_assemblerPath;
 234         needsCompilerOptions = false;
 235     } else {
 236         // find compiler driver
 237         tool = sys::Program::FindProgramByName("gcc");
 238         if ( tool.isEmpty() ) {
 239             errMsg = "can't locate gcc";
 240             return true;
 241         }
 242     }
 243
 244     // build argument list
 245     std::vector<const char*> args;
 246     llvm::Triple targetTriple(_linker.getModule()->getTargetTriple());
 247     const char *arch = targetTriple.getArchNameForAssembler();
 248
 249     args.push_back(tool.c_str());
 250
 251     if (targetTriple.getOS() == Triple::Darwin) {
 252         // darwin specific command line options
 253         if (arch != NULL) {
 254             args.push_back("-arch");
 255             args.push_back(arch);
 256         }
 257         // add -static to assembler command line when code model requires
 258         if ( (_assemblerPath != NULL) && (_codeModel == LTO_CODEGEN_PIC_MODEL_STATIC) )
 259             args.push_back("-static");
 260     }
 261     if ( needsCompilerOptions ) {
 262         args.push_back("-c");
 263         args.push_back("-x");
 264         args.push_back("assembler");
 265     }
 266     args.push_back("-o");
 267     args.push_back(objPath.c_str());
 268     args.push_back(asmPath.c_str());
 269     args.push_back(0);
 270
 271     // invoke assembler
 272     if ( sys::Program::ExecuteAndWait(tool, &args[0], 0, 0, 0, 0, &errMsg) ) {
 273         errMsg = "error in assembly";
 274         return true;
 275     }
 276     return false; // success
 277 }
 278
 279
 280
 281 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
 282 {
 283     if ( _target == NULL ) {
 284         std::string Triple = _linker.getModule()->getTargetTriple();
 285         if (Triple.empty())
 286           Triple = sys::getHostTriple();
 287
 288         // create target machine from info for merged modules
 289         const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
 290         if ( march == NULL )
 291             return true;
 292
 293         // The relocation model is actually a static member of TargetMachine
 294         // and needs to be set before the TargetMachine is instantiated.
 295         switch( _codeModel ) {
 296         case LTO_CODEGEN_PIC_MODEL_STATIC:
 297             TargetMachine::setRelocationModel(Reloc::Static);
 298             break;
 299         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 300             TargetMachine::setRelocationModel(Reloc::PIC_);
 301             break;
 302         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 303             TargetMachine::setRelocationModel(Reloc::DynamicNoPIC);
 304             break;
 305         }
 306
 307         // Prepare subtarget feature set for the given command line options.
 308         SubtargetFeatures features;
 309
 310         // Set the rest of features by default.
 311         // Note: Please keep this after all explict feature settings to make sure
 312         // defaults will not override explicitly set options.
 313         features.AddFeatures(
 314             SubtargetFeatures::getDefaultSubtargetFeatures(llvm::Triple(Triple)));
 315
 316         // construct LTModule, hand over ownership of module and target
 317         _target = march->createTargetMachine(Triple, features.getString());
 318     }
 319     return false;
 320 }
 321
 322 void LTOCodeGenerator::applyScopeRestrictions()
 323 {
 324     if ( !_scopeRestrictionsDone ) {
 325         Module* mergedModule = _linker.getModule();
 326
 327         // Start off with a verification pass.
 328         PassManager passes;
 329         passes.add(createVerifierPass());
 330
 331         // mark which symbols can not be internalized
 332         if ( !_mustPreserveSymbols.empty() ) {
 333             Mangler mangler(*mergedModule,
 334                                 _target->getMCAsmInfo()->getGlobalPrefix());
 335             std::vector<const char*> mustPreserveList;
 336             for (Module::iterator f = mergedModule->begin(),
 337                                         e = mergedModule->end(); f != e; ++f) {
 338                 if ( !f->isDeclaration()
 339                   && _mustPreserveSymbols.count(mangler.getMangledName(f)) )
 340                   mustPreserveList.push_back(::strdup(f->getNameStr().c_str()));
 341             }
 342             for (Module::global_iterator v = mergedModule->global_begin(),
 343                                  e = mergedModule->global_end(); v !=  e; ++v) {
 344                 if ( !v->isDeclaration()
 345                   && _mustPreserveSymbols.count(mangler.getMangledName(v)) )
 346                   mustPreserveList.push_back(::strdup(v->getNameStr().c_str()));
 347             }
 348             passes.add(createInternalizePass(mustPreserveList));
 349         }
 350         // apply scope restrictions
 351         passes.run(*mergedModule);
 352
 353         _scopeRestrictionsDone = true;
 354     }
 355 }
 356
 357 /// Optimize merged modules using various IPO passes
 358 bool LTOCodeGenerator::generateAssemblyCode(formatted_raw_ostream& out,
 359                                             std::string& errMsg)
 360 {
 361     if ( this->determineTarget(errMsg) )
 362         return true;
 363
 364     // mark which symbols can not be internalized
 365     this->applyScopeRestrictions();
 366
 367     Module* mergedModule = _linker.getModule();
 368
 369     // If target supports exception handling then enable it now.
 370     switch (_target->getMCAsmInfo()->getExceptionHandlingType()) {
 371     case ExceptionHandling::Dwarf:
 372       llvm::DwarfExceptionHandling = true;
 373       break;
 374     case ExceptionHandling::SjLj:
 375       llvm::SjLjExceptionHandling = true;
 376       break;
 377     case ExceptionHandling::None:
 378       break;
 379     default:
 380       assert (0 && "Unknown exception handling model!");
 381     }
 382
 383     // if options were requested, set them
 384     if ( !_codegenOptions.empty() )
 385         cl::ParseCommandLineOptions(_codegenOptions.size(),
 386                                                 (char**)&_codegenOptions[0]);
 387
 388     // Instantiate the pass manager to organize the passes.
 389     PassManager passes;
 390
 391     // Start off with a verification pass.
 392     passes.add(createVerifierPass());
 393
 394     // Add an appropriate TargetData instance for this module...
 395     passes.add(new TargetData(*_target->getTargetData()));
 396
 397     createStandardLTOPasses(&passes, /*Internalize=*/ false, !DisableInline,
 398                             /*VerifyEach=*/ false);
 399
 400     // Make sure everything is still good.
 401     passes.add(createVerifierPass());
 402
 403     FunctionPassManager* codeGenPasses =
 404             new FunctionPassManager(new ExistingModuleProvider(mergedModule));
 405
 406     codeGenPasses->add(new TargetData(*_target->getTargetData()));
 407
 408     ObjectCodeEmitter* oce = NULL;
 409
 410     switch (_target->addPassesToEmitFile(*codeGenPasses, out,
 411                                          TargetMachine::AssemblyFile,
 412                                          CodeGenOpt::Aggressive)) {
 413         case FileModel::MachOFile:
 414             oce = AddMachOWriter(*codeGenPasses, out, *_target);
 415             break;
 416         case FileModel::ElfFile:
 417             oce = AddELFWriter(*codeGenPasses, out, *_target);
 418             break;
 419         case FileModel::AsmFile:
 420             break;
 421         case FileModel::Error:
 422         case FileModel::None:
 423             errMsg = "target file type not supported";
 424             return true;
 425     }
 426
 427     if (_target->addPassesToEmitFileFinish(*codeGenPasses, oce,
 428                                            CodeGenOpt::Aggressive)) {
 429         errMsg = "target does not support generation of this file type";
 430         return true;
 431     }
 432
 433     // Run our queue of passes all at once now, efficiently.
 434     passes.run(*mergedModule);
 435
 436     // Run the code generator, and write assembly file
 437     codeGenPasses->doInitialization();
 438
 439     for (Module::iterator
 440            it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
 441       if (!it->isDeclaration())
 442         codeGenPasses->run(*it);
 443
 444     codeGenPasses->doFinalization();
 445
 446     return false; // success
 447 }
 448
 449
 450 /// Optimize merged modules using various IPO passes
 451 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
 452 {
 453     std::string ops(options);
 454     for (std::string o = getToken(ops); !o.empty(); o = getToken(ops)) {
 455         // ParseCommandLineOptions() expects argv[0] to be program name.
 456         // Lazily add that.
 457         if ( _codegenOptions.empty() )
 458             _codegenOptions.push_back("libLTO");
 459         _codegenOptions.push_back(strdup(o.c_str()));
 460     }
 461 }