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/Bitcode/ReaderWriter.h"
  28 #include "llvm/MC/MCAsmInfo.h"
  29 #include "llvm/MC/MCContext.h"
  30 #include "llvm/Target/Mangler.h"
  31 #include "llvm/Target/SubtargetFeature.h"
  32 #include "llvm/Target/TargetOptions.h"
  33 #include "llvm/Target/TargetData.h"
  34 #include "llvm/Target/TargetMachine.h"
  35 #include "llvm/Target/TargetRegistry.h"
  36 #include "llvm/Target/TargetSelect.h"
  37 #include "llvm/Support/CommandLine.h"
  38 #include "llvm/Support/FormattedStream.h"
  39 #include "llvm/Support/MemoryBuffer.h"
  40 #include "llvm/Support/StandardPasses.h"
  41 #include "llvm/Support/SystemUtils.h"
  42 #include "llvm/Support/ToolOutputFile.h"
  43 #include "llvm/Support/Host.h"
  44 #include "llvm/Support/Program.h"
  45 #include "llvm/Support/Signals.h"
  46 #include "llvm/Support/system_error.h"
  47 #include "llvm/Config/config.h"
  48 #include <cstdlib>
  49 #include <unistd.h>
  50 #include <fcntl.h>
  51
  52
  53 using namespace llvm;
  54
  55 static cl::opt<bool> DisableInline("disable-inlining",
  56   cl::desc("Do not run the inliner pass"));
  57
  58
  59 const char* LTOCodeGenerator::getVersionString()
  60 {
  61 #ifdef LLVM_VERSION_INFO
  62     return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
  63 #else
  64     return PACKAGE_NAME " version " PACKAGE_VERSION;
  65 #endif
  66 }
  67
  68
  69 LTOCodeGenerator::LTOCodeGenerator()
  70     : _context(getGlobalContext()),
  71       _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
  72       _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
  73       _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
  74       _nativeObjectFile(NULL), _assemblerPath(NULL)
  75 {
  76     InitializeAllTargets();
  77     InitializeAllAsmPrinters();
  78 }
  79
  80 LTOCodeGenerator::~LTOCodeGenerator()
  81 {
  82     delete _target;
  83     delete _nativeObjectFile;
  84 }
  85
  86
  87
  88 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg)
  89 {
  90     return _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
  91 }
  92
  93
  94 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg)
  95 {
  96     switch (debug) {
  97         case LTO_DEBUG_MODEL_NONE:
  98             _emitDwarfDebugInfo = false;
  99             return false;
 100
 101         case LTO_DEBUG_MODEL_DWARF:
 102             _emitDwarfDebugInfo = true;
 103             return false;
 104     }
 105     errMsg = "unknown debug format";
 106     return true;
 107 }
 108
 109
 110 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
 111                                        std::string& errMsg)
 112 {
 113     switch (model) {
 114         case LTO_CODEGEN_PIC_MODEL_STATIC:
 115         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 116         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 117             _codeModel = model;
 118             return false;
 119     }
 120     errMsg = "unknown pic model";
 121     return true;
 122 }
 123
 124 void LTOCodeGenerator::setCpu(const char* mCpu)
 125 {
 126   _mCpu = mCpu;
 127 }
 128
 129 void LTOCodeGenerator::setAssemblerPath(const char* path)
 130 {
 131     if ( _assemblerPath )
 132         delete _assemblerPath;
 133     _assemblerPath = new sys::Path(path);
 134 }
 135
 136 void LTOCodeGenerator::setAssemblerArgs(const char** args, int nargs)
 137 {
 138   for (int i = 0; i < nargs; ++i) {
 139     const char *arg = args[i];
 140     _assemblerArgs.push_back(arg);
 141   }
 142 }
 143
 144 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
 145 {
 146     _mustPreserveSymbols[sym] = 1;
 147 }
 148
 149
 150 bool LTOCodeGenerator::writeMergedModules(const char *path,
 151                                           std::string &errMsg) {
 152   if (determineTarget(errMsg))
 153     return true;
 154
 155   // mark which symbols can not be internalized
 156   applyScopeRestrictions();
 157
 158   // create output file
 159   std::string ErrInfo;
 160   tool_output_file Out(path, ErrInfo,
 161                        raw_fd_ostream::F_Binary);
 162   if (!ErrInfo.empty()) {
 163     errMsg = "could not open bitcode file for writing: ";
 164     errMsg += path;
 165     return true;
 166   }
 167
 168   // write bitcode to it
 169   WriteBitcodeToFile(_linker.getModule(), Out.os());
 170   Out.os().close();
 171
 172   if (Out.os().has_error()) {
 173     errMsg = "could not write bitcode file: ";
 174     errMsg += path;
 175     Out.os().clear_error();
 176     return true;
 177   }
 178
 179   Out.keep();
 180   return false;
 181 }
 182
 183
 184 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
 185 {
 186     // make unique temp .s file to put generated assembly code
 187     sys::Path uniqueAsmPath("lto-llvm.s");
 188     if ( uniqueAsmPath.createTemporaryFileOnDisk(false, &errMsg) )
 189         return NULL;
 190     sys::RemoveFileOnSignal(uniqueAsmPath);
 191
 192     // generate assembly code
 193     bool genResult = false;
 194     {
 195       tool_output_file asmFile(uniqueAsmPath.c_str(), errMsg);
 196       if (!errMsg.empty())
 197         return NULL;
 198       genResult = this->generateAssemblyCode(asmFile.os(), errMsg);
 199       asmFile.os().close();
 200       if (asmFile.os().has_error()) {
 201         asmFile.os().clear_error();
 202         return NULL;
 203       }
 204       asmFile.keep();
 205     }
 206     if ( genResult ) {
 207         uniqueAsmPath.eraseFromDisk();
 208         return NULL;
 209     }
 210
 211     // make unique temp .o file to put generated object file
 212     sys::PathWithStatus uniqueObjPath("lto-llvm.o");
 213     if ( uniqueObjPath.createTemporaryFileOnDisk(false, &errMsg) ) {
 214         uniqueAsmPath.eraseFromDisk();
 215         return NULL;
 216     }
 217     sys::RemoveFileOnSignal(uniqueObjPath);
 218
 219     // assemble the assembly code
 220     const std::string& uniqueObjStr = uniqueObjPath.str();
 221     bool asmResult = this->assemble(uniqueAsmPath.str(), uniqueObjStr, errMsg);
 222     if ( !asmResult ) {
 223         // remove old buffer if compile() called twice
 224         delete _nativeObjectFile;
 225
 226         // read .o file into memory buffer
 227         OwningPtr<MemoryBuffer> BuffPtr;
 228         if (error_code ec = MemoryBuffer::getFile(uniqueObjStr.c_str(),BuffPtr))
 229           errMsg = ec.message();
 230         _nativeObjectFile = BuffPtr.take();
 231     }
 232
 233     // remove temp files
 234     uniqueAsmPath.eraseFromDisk();
 235     uniqueObjPath.eraseFromDisk();
 236
 237     // return buffer, unless error
 238     if ( _nativeObjectFile == NULL )
 239         return NULL;
 240     *length = _nativeObjectFile->getBufferSize();
 241     return _nativeObjectFile->getBufferStart();
 242 }
 243
 244
 245 bool LTOCodeGenerator::assemble(const std::string& asmPath,
 246                                 const std::string& objPath, std::string& errMsg)
 247 {
 248     sys::Path tool;
 249     bool needsCompilerOptions = true;
 250     if ( _assemblerPath ) {
 251         tool = *_assemblerPath;
 252         needsCompilerOptions = false;
 253     } else {
 254         // find compiler driver
 255         tool = sys::Program::FindProgramByName("gcc");
 256         if ( tool.isEmpty() ) {
 257             errMsg = "can't locate gcc";
 258             return true;
 259         }
 260     }
 261
 262     // build argument list
 263     std::vector<const char*> args;
 264     llvm::Triple targetTriple(_linker.getModule()->getTargetTriple());
 265     const char *arch = targetTriple.getArchNameForAssembler();
 266
 267     args.push_back(tool.c_str());
 268
 269     if (targetTriple.getOS() == Triple::Darwin) {
 270         // darwin specific command line options
 271         if (arch != NULL) {
 272             args.push_back("-arch");
 273             args.push_back(arch);
 274         }
 275         // add -static to assembler command line when code model requires
 276         if ( (_assemblerPath != NULL) &&
 277             (_codeModel == LTO_CODEGEN_PIC_MODEL_STATIC) )
 278             args.push_back("-static");
 279     }
 280     if ( needsCompilerOptions ) {
 281         args.push_back("-c");
 282         args.push_back("-x");
 283         args.push_back("assembler");
 284     } else {
 285         for (std::vector<std::string>::iterator I = _assemblerArgs.begin(),
 286                E = _assemblerArgs.end(); I != E; ++I) {
 287             args.push_back(I->c_str());
 288         }
 289     }
 290     args.push_back("-o");
 291     args.push_back(objPath.c_str());
 292     args.push_back(asmPath.c_str());
 293     args.push_back(0);
 294
 295     // invoke assembler
 296     if ( sys::Program::ExecuteAndWait(tool, &args[0], 0, 0, 0, 0, &errMsg) ) {
 297         errMsg = "error in assembly";
 298         return true;
 299     }
 300     return false; // success
 301 }
 302
 303
 304
 305 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
 306 {
 307     if ( _target == NULL ) {
 308         std::string Triple = _linker.getModule()->getTargetTriple();
 309         if (Triple.empty())
 310           Triple = sys::getHostTriple();
 311
 312         // create target machine from info for merged modules
 313         const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
 314         if ( march == NULL )
 315             return true;
 316
 317         // The relocation model is actually a static member of TargetMachine
 318         // and needs to be set before the TargetMachine is instantiated.
 319         switch( _codeModel ) {
 320         case LTO_CODEGEN_PIC_MODEL_STATIC:
 321             TargetMachine::setRelocationModel(Reloc::Static);
 322             break;
 323         case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
 324             TargetMachine::setRelocationModel(Reloc::PIC_);
 325             break;
 326         case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
 327             TargetMachine::setRelocationModel(Reloc::DynamicNoPIC);
 328             break;
 329         }
 330
 331         // construct LTModule, hand over ownership of module and target
 332         SubtargetFeatures Features;
 333         Features.getDefaultSubtargetFeatures(_mCpu, llvm::Triple(Triple));
 334         std::string FeatureStr = Features.getString();
 335         _target = march->createTargetMachine(Triple, FeatureStr);
 336     }
 337     return false;
 338 }
 339
 340 void LTOCodeGenerator::applyScopeRestrictions() {
 341   if (_scopeRestrictionsDone) return;
 342   Module *mergedModule = _linker.getModule();
 343
 344   // Start off with a verification pass.
 345   PassManager passes;
 346   passes.add(createVerifierPass());
 347
 348   // mark which symbols can not be internalized
 349   if (!_mustPreserveSymbols.empty()) {
 350     MCContext Context(*_target->getMCAsmInfo(), NULL);
 351     Mangler mangler(Context, *_target->getTargetData());
 352     std::vector<const char*> mustPreserveList;
 353     for (Module::iterator f = mergedModule->begin(),
 354          e = mergedModule->end(); f != e; ++f) {
 355       if (!f->isDeclaration() &&
 356           _mustPreserveSymbols.count(mangler.getNameWithPrefix(f)))
 357         mustPreserveList.push_back(::strdup(f->getNameStr().c_str()));
 358     }
 359     for (Module::global_iterator v = mergedModule->global_begin(),
 360          e = mergedModule->global_end(); v !=  e; ++v) {
 361       if (!v->isDeclaration() &&
 362           _mustPreserveSymbols.count(mangler.getNameWithPrefix(v)))
 363         mustPreserveList.push_back(::strdup(v->getNameStr().c_str()));
 364     }
 365     passes.add(createInternalizePass(mustPreserveList));
 366   }
 367
 368   // apply scope restrictions
 369   passes.run(*mergedModule);
 370
 371   _scopeRestrictionsDone = true;
 372 }
 373
 374 /// Optimize merged modules using various IPO passes
 375 bool LTOCodeGenerator::generateAssemblyCode(raw_ostream& out,
 376                                             std::string& errMsg)
 377 {
 378     if ( this->determineTarget(errMsg) )
 379         return true;
 380
 381     // mark which symbols can not be internalized
 382     this->applyScopeRestrictions();
 383
 384     Module* mergedModule = _linker.getModule();
 385
 386     // if options were requested, set them
 387     if ( !_codegenOptions.empty() )
 388         cl::ParseCommandLineOptions(_codegenOptions.size(),
 389                                     const_cast<char **>(&_codegenOptions[0]));
 390
 391     // Instantiate the pass manager to organize the passes.
 392     PassManager passes;
 393
 394     // Start off with a verification pass.
 395     passes.add(createVerifierPass());
 396
 397     // Add an appropriate TargetData instance for this module...
 398     passes.add(new TargetData(*_target->getTargetData()));
 399
 400     createStandardLTOPasses(&passes, /*Internalize=*/ false, !DisableInline,
 401                             /*VerifyEach=*/ false);
 402
 403     // Make sure everything is still good.
 404     passes.add(createVerifierPass());
 405
 406     FunctionPassManager* codeGenPasses = new FunctionPassManager(mergedModule);
 407
 408     codeGenPasses->add(new TargetData(*_target->getTargetData()));
 409
 410     formatted_raw_ostream Out(out);
 411
 412     if (_target->addPassesToEmitFile(*codeGenPasses, Out,
 413                                      TargetMachine::CGFT_AssemblyFile,
 414                                      CodeGenOpt::Aggressive)) {
 415       errMsg = "target file type not supported";
 416       return true;
 417     }
 418
 419     // Run our queue of passes all at once now, efficiently.
 420     passes.run(*mergedModule);
 421
 422     // Run the code generator, and write assembly file
 423     codeGenPasses->doInitialization();
 424
 425     for (Module::iterator
 426            it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
 427       if (!it->isDeclaration())
 428         codeGenPasses->run(*it);
 429
 430     codeGenPasses->doFinalization();
 431
 432     return false; // success
 433 }
 434
 435
 436 /// Optimize merged modules using various IPO passes
 437 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
 438 {
 439     for (std::pair<StringRef, StringRef> o = getToken(options);
 440          !o.first.empty(); o = getToken(o.second)) {
 441         // ParseCommandLineOptions() expects argv[0] to be program name.
 442         // Lazily add that.
 443         if ( _codegenOptions.empty() )
 444             _codegenOptions.push_back("libLTO");
 445         _codegenOptions.push_back(strdup(o.first.str().c_str()));
 446     }
 447 }