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/Analysis/Passes.h"
  28 #include "llvm/Analysis/LoopPass.h"
  29 #include "llvm/Analysis/Verifier.h"
  30 #include "llvm/Bitcode/ReaderWriter.h"
  31 #include "llvm/CodeGen/FileWriters.h"
  32 #include "llvm/Support/CommandLine.h"
  33 #include "llvm/Support/FormattedStream.h"
  34 #include "llvm/Support/Mangler.h"
  35 #include "llvm/Support/MemoryBuffer.h"
  36 #include "llvm/Support/StandardPasses.h"
  37 #include "llvm/Support/SystemUtils.h"
  38 #include "llvm/System/Signals.h"
  39 #include "llvm/Target/SubtargetFeature.h"
  40 #include "llvm/Target/TargetOptions.h"
  41 #include "llvm/Target/TargetAsmInfo.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
  50
  51 #include <cstdlib>
  52 #include <fstream>
  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), _gccPath(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::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 asmFD(raw_fd_ostream(uniqueAsmPath.c_str(),
 188                                           /*Binary=*/false, /*Force=*/true,
 189                                           errMsg));
 190       formatted_raw_ostream asmFile(asmFD);
 191       if (!errMsg.empty())
 192         return NULL;
 193       genResult = this->generateAssemblyCode(asmFile, errMsg);
 194     }
 195     if ( genResult ) {
 196         if ( uniqueAsmPath.exists() )
 197             uniqueAsmPath.eraseFromDisk();
 198         return NULL;
 199     }
 200
 201     // make unique temp .o file to put generated object file
 202     sys::PathWithStatus uniqueObjPath("lto-llvm.o");
 203     if ( uniqueObjPath.createTemporaryFileOnDisk(true, &errMsg) ) {
 204         if ( uniqueAsmPath.exists() )
 205             uniqueAsmPath.eraseFromDisk();
 206         return NULL;
 207     }
 208     sys::RemoveFileOnSignal(uniqueObjPath);
 209
 210     // assemble the assembly code
 211     const std::string& uniqueObjStr = uniqueObjPath.toString();
 212     bool asmResult = this->assemble(uniqueAsmPath.toString(),
 213                                                         uniqueObjStr, errMsg);
 214     if ( !asmResult ) {
 215         // remove old buffer if compile() called twice
 216         delete _nativeObjectFile;
 217
 218         // read .o file into memory buffer
 219         _nativeObjectFile = MemoryBuffer::getFile(uniqueObjStr.c_str(),&errMsg);
 220     }
 221
 222     // remove temp files
 223     uniqueAsmPath.eraseFromDisk();
 224     uniqueObjPath.eraseFromDisk();
 225
 226     // return buffer, unless error
 227     if ( _nativeObjectFile == NULL )
 228         return NULL;
 229     *length = _nativeObjectFile->getBufferSize();
 230     return _nativeObjectFile->getBufferStart();
 231 }
 232
 233
 234 bool LTOCodeGenerator::assemble(const std::string& asmPath,
 235                                 const std::string& objPath, std::string& errMsg)
 236 {
 237     sys::Path tool;
 238     bool needsCompilerOptions = true;
 239     if ( _assemblerPath ) {
 240         tool = *_assemblerPath;
 241         needsCompilerOptions = false;
 242     }
 243     else if ( _gccPath ) {
 244         tool = *_gccPath;
 245     } else {
 246         // find compiler driver
 247         tool = sys::Program::FindProgramByName("gcc");
 248         if ( tool.isEmpty() ) {
 249             errMsg = "can't locate gcc";
 250             return true;
 251         }
 252     }
 253
 254     // build argument list
 255     std::vector<const char*> args;
 256     std::string targetTriple = _linker.getModule()->getTargetTriple();
 257     args.push_back(tool.c_str());
 258     if ( targetTriple.find("darwin") != std::string::npos ) {
 259         // darwin specific command line options
 260         if (strncmp(targetTriple.c_str(), "i386-apple-", 11) == 0) {
 261             args.push_back("-arch");
 262             args.push_back("i386");
 263         }
 264         else if (strncmp(targetTriple.c_str(), "x86_64-apple-", 13) == 0) {
 265             args.push_back("-arch");
 266             args.push_back("x86_64");
 267         }
 268         else if (strncmp(targetTriple.c_str(), "powerpc-apple-", 14) == 0) {
 269             args.push_back("-arch");
 270             args.push_back("ppc");
 271         }
 272         else if (strncmp(targetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
 273             args.push_back("-arch");
 274             args.push_back("ppc64");
 275         }
 276         else if (strncmp(targetTriple.c_str(), "arm-apple-", 10) == 0) {
 277             args.push_back("-arch");
 278             args.push_back("arm");
 279         }
 280         else if ((strncmp(targetTriple.c_str(), "armv4t-apple-", 13) == 0) ||
 281                  (strncmp(targetTriple.c_str(), "thumbv4t-apple-", 15) == 0)) {
 282             args.push_back("-arch");
 283             args.push_back("armv4t");
 284         }
 285         else if ((strncmp(targetTriple.c_str(), "armv5-apple-", 12) == 0) ||
 286                  (strncmp(targetTriple.c_str(), "armv5e-apple-", 13) == 0) ||
 287                  (strncmp(targetTriple.c_str(), "thumbv5-apple-", 14) == 0) ||
 288                  (strncmp(targetTriple.c_str(), "thumbv5e-apple-", 15) == 0)) {
 289             args.push_back("-arch");
 290             args.push_back("armv5");
 291         }
 292         else if ((strncmp(targetTriple.c_str(), "armv6-apple-", 12) == 0) ||
 293                  (strncmp(targetTriple.c_str(), "thumbv6-apple-", 14) == 0)) {
 294             args.push_back("-arch");
 295             args.push_back("armv6");
 296         }
 297         else if ((strncmp(targetTriple.c_str(), "armv7-apple-", 12) == 0) ||
 298                  (strncmp(targetTriple.c_str(), "thumbv7-apple-", 14) == 0)) {
 299             args.push_back("-arch");
 300             args.push_back("armv7");
 301         }
 302         // add -static to assembler command line when code model requires
 303         if ( (_assemblerPath != NULL) && (_codeModel == LTO_CODEGEN_PIC_MODEL_STATIC) )
 304             args.push_back("-static");
 305     }
 306     if ( needsCompilerOptions ) {
 307         args.push_back("-c");
 308         args.push_back("-x");
 309         args.push_back("assembler");
 310     }
 311     args.push_back("-o");
 312     args.push_back(objPath.c_str());
 313     args.push_back(asmPath.c_str());
 314     args.push_back(0);
 315
 316     // invoke assembler
 317     if ( sys::Program::ExecuteAndWait(tool, &args[0], 0, 0, 0, 0, &errMsg) ) {
 318         errMsg = "error in assembly";
 319         return true;
 320     }
 321     return false; // success
 322 }
 323
 324
 325
 326 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
 327 {
 328     if ( _target == NULL ) {
 329         // create target machine from info for merged modules
 330         Module* mergedModule = _linker.getModule();
 331         const Target *march =
 332           TargetRegistry::lookupTarget(mergedModule->getTargetTriple(),
 333                                        /*FallbackToHost=*/true,
 334                                        /*RequireJIT=*/false,
 335                                        errMsg);
 336         if ( march == NULL )
 337             return true;
 338
 339         // The relocation model is actually a static member of TargetMachine
 340         // and needs to be set before the TargetMachine is instantiated.
 341         switch( _codeModel ) {
 342         case LTO_CODEGEN_PIC_MODEL_STATIC:
 343             TargetMachine::setRelocationModel(Reloc::Static);
 344             break;
 345         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 346             TargetMachine::setRelocationModel(Reloc::PIC_);
 347             break;
 348         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 349             TargetMachine::setRelocationModel(Reloc::DynamicNoPIC);
 350             break;
 351         }
 352
 353         // construct LTModule, hand over ownership of module and target
 354         std::string FeatureStr =
 355           getFeatureString(_linker.getModule()->getTargetTriple().c_str());
 356         _target = march->createTargetMachine(*mergedModule, FeatureStr.c_str());
 357     }
 358     return false;
 359 }
 360
 361 void LTOCodeGenerator::applyScopeRestrictions()
 362 {
 363     if ( !_scopeRestrictionsDone ) {
 364         Module* mergedModule = _linker.getModule();
 365
 366         // Start off with a verification pass.
 367         PassManager passes;
 368         passes.add(createVerifierPass());
 369
 370         // mark which symbols can not be internalized
 371         if ( !_mustPreserveSymbols.empty() ) {
 372             Mangler mangler(*mergedModule,
 373                                 _target->getTargetAsmInfo()->getGlobalPrefix());
 374             std::vector<const char*> mustPreserveList;
 375             for (Module::iterator f = mergedModule->begin(),
 376                                         e = mergedModule->end(); f != e; ++f) {
 377                 if ( !f->isDeclaration()
 378                   && _mustPreserveSymbols.count(mangler.getMangledName(f)) )
 379                   mustPreserveList.push_back(::strdup(f->getNameStr().c_str()));
 380             }
 381             for (Module::global_iterator v = mergedModule->global_begin(),
 382                                  e = mergedModule->global_end(); v !=  e; ++v) {
 383                 if ( !v->isDeclaration()
 384                   && _mustPreserveSymbols.count(mangler.getMangledName(v)) )
 385                   mustPreserveList.push_back(::strdup(v->getNameStr().c_str()));
 386             }
 387             passes.add(createInternalizePass(mustPreserveList));
 388         }
 389         // apply scope restrictions
 390         passes.run(*mergedModule);
 391
 392         _scopeRestrictionsDone = true;
 393     }
 394 }
 395
 396 /// Optimize merged modules using various IPO passes
 397 bool LTOCodeGenerator::generateAssemblyCode(formatted_raw_ostream& out,
 398                                             std::string& errMsg)
 399 {
 400     if ( this->determineTarget(errMsg) )
 401         return true;
 402
 403     // mark which symbols can not be internalized
 404     this->applyScopeRestrictions();
 405
 406     Module* mergedModule = _linker.getModule();
 407
 408      // If target supports exception handling then enable it now.
 409     if ( _target->getTargetAsmInfo()->doesSupportExceptionHandling() )
 410         llvm::ExceptionHandling = true;
 411
 412     // if options were requested, set them
 413     if ( !_codegenOptions.empty() )
 414         cl::ParseCommandLineOptions(_codegenOptions.size(),
 415                                                 (char**)&_codegenOptions[0]);
 416
 417     // Instantiate the pass manager to organize the passes.
 418     PassManager passes;
 419
 420     // Start off with a verification pass.
 421     passes.add(createVerifierPass());
 422
 423     // Add an appropriate TargetData instance for this module...
 424     passes.add(new TargetData(*_target->getTargetData()));
 425
 426     createStandardLTOPasses(&passes, /*Internalize=*/ false, !DisableInline,
 427                             /*VerifyEach=*/ false);
 428
 429     // Make sure everything is still good.
 430     passes.add(createVerifierPass());
 431
 432     FunctionPassManager* codeGenPasses =
 433             new FunctionPassManager(new ExistingModuleProvider(mergedModule));
 434
 435     codeGenPasses->add(new TargetData(*_target->getTargetData()));
 436
 437     ObjectCodeEmitter* oce = NULL;
 438
 439     switch (_target->addPassesToEmitFile(*codeGenPasses, out,
 440                                          TargetMachine::AssemblyFile,
 441                                          CodeGenOpt::Aggressive)) {
 442         case FileModel::MachOFile:
 443             oce = AddMachOWriter(*codeGenPasses, out, *_target);
 444             break;
 445         case FileModel::ElfFile:
 446             oce = AddELFWriter(*codeGenPasses, out, *_target);
 447             break;
 448         case FileModel::AsmFile:
 449             break;
 450         case FileModel::Error:
 451         case FileModel::None:
 452             errMsg = "target file type not supported";
 453             return true;
 454     }
 455
 456     if (_target->addPassesToEmitFileFinish(*codeGenPasses, oce,
 457                                            CodeGenOpt::Aggressive)) {
 458         errMsg = "target does not support generation of this file type";
 459         return true;
 460     }
 461
 462     // Run our queue of passes all at once now, efficiently.
 463     passes.run(*mergedModule);
 464
 465     // Run the code generator, and write assembly file
 466     codeGenPasses->doInitialization();
 467
 468     for (Module::iterator
 469            it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
 470       if (!it->isDeclaration())
 471         codeGenPasses->run(*it);
 472
 473     codeGenPasses->doFinalization();
 474
 475     out.flush();
 476
 477     return false; // success
 478 }
 479
 480
 481 /// Optimize merged modules using various IPO passes
 482 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
 483 {
 484     std::string ops(options);
 485     for (std::string o = getToken(ops); !o.empty(); o = getToken(ops)) {
 486         // ParseCommandLineOptions() expects argv[0] to be program name.
 487         // Lazily add that.
 488         if ( _codegenOptions.empty() )
 489             _codegenOptions.push_back("libLTO");
 490         _codegenOptions.push_back(strdup(o.c_str()));
 491     }
 492 }