Beispiel #1
0
void LTOCodeGenerator::
applyRestriction(GlobalValue &GV,
                 ArrayRef<StringRef> Libcalls,
                 std::vector<const char*> &MustPreserveList,
                 SmallPtrSetImpl<GlobalValue*> &AsmUsed,
                 Mangler &Mangler) {
  // There are no restrictions to apply to declarations.
  if (GV.isDeclaration())
    return;

  // There is nothing more restrictive than private linkage.
  if (GV.hasPrivateLinkage())
    return;

  SmallString<64> Buffer;
  TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);

  if (MustPreserveSymbols.count(Buffer))
    MustPreserveList.push_back(GV.getName().data());
  if (AsmUndefinedRefs.count(Buffer))
    AsmUsed.insert(&GV);

  // Conservatively append user-supplied runtime library functions to
  // llvm.compiler.used.  These could be internalized and deleted by
  // optimizations like -globalopt, causing problems when later optimizations
  // add new library calls (e.g., llvm.memset => memset and printf => puts).
  // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
  if (isa<Function>(GV) &&
      std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
    AsmUsed.insert(&GV);
}
Beispiel #2
0
static void DumpSymbolNameForGlobalValue(GlobalValue &GV) {
  // Private linkage and available_externally linkage don't exist in symtab.
  if (GV.hasPrivateLinkage() || GV.hasLinkerPrivateLinkage() ||
      GV.hasLinkerPrivateWeakLinkage() || GV.hasAvailableExternallyLinkage())
    return;
  
  const std::string SymbolAddrStr = "        "; // Not used yet...
  char TypeChar = TypeCharForSymbol(GV);
  if ((TypeChar != 'U') && UndefinedOnly)
    return;
  if ((TypeChar == 'U') && DefinedOnly)
    return;
  if (GV.hasLocalLinkage () && ExternalOnly)
    return;
  if (OutputFormat == posix) {
    outs() << GV.getName () << " " << TypeCharForSymbol(GV) << " "
           << SymbolAddrStr << "\n";
  } else if (OutputFormat == bsd) {
    outs() << SymbolAddrStr << " " << TypeCharForSymbol(GV) << " "
           << GV.getName () << "\n";
  } else if (OutputFormat == sysv) {
    std::string PaddedName (GV.getName ());
    while (PaddedName.length () < 20)
      PaddedName += " ";
    outs() << PaddedName << "|" << SymbolAddrStr << "|   "
           << TypeCharForSymbol(GV)
           << "  |                  |      |     |\n";
  }
}
Beispiel #3
0
static bool shouldInternalize(const GlobalValue &GV,
                              const std::set<std::string> &ExternalNames,
                              const std::set<std::string> &DSONames) {
  // Function must be defined here
  if (GV.isDeclaration())
    return false;

  // Available externally is really just a "declaration with a body".
  if (GV.hasAvailableExternallyLinkage())
    return false;

  // Already has internal linkage
  if (GV.hasLocalLinkage())
    return false;

  // Marked to keep external?
  if (ExternalNames.count(GV.getName()))
    return false;

  // Not needed for the symbol table?
  if (!DSONames.count(GV.getName()))
    return true;

  // Not a linkonce. Someone can depend on it being on the symbol table.
  if (!GV.hasLinkOnceLinkage())
    return false;

  // The address is not important, we can hide it.
  if (GV.hasUnnamedAddr())
    return true;

  // FIXME: Check if the address is used.
  return false;
}
Beispiel #4
0
void ModuleLinker::addLazyFor(GlobalValue &GV, IRMover::ValueAdder Add) {
  if (!shouldLinkReferencedLinkOnce())
    // For ThinLTO we don't import more than what was required.
    // The client has to guarantee that the linkonce will be availabe at link
    // time (by promoting it to weak for instance).
    return;

  // Add these to the internalize list
  if (!GV.hasLinkOnceLinkage() && !shouldLinkOnlyNeeded())
    return;

  if (shouldInternalizeLinkedSymbols())
    Internalize.insert(GV.getName());
  Add(GV);

  const Comdat *SC = GV.getComdat();
  if (!SC)
    return;
  for (GlobalValue *GV2 : LazyComdatMembers[SC]) {
    GlobalValue *DGV = getLinkedToGlobal(GV2);
    bool LinkFromSrc = true;
    if (DGV && shouldLinkFromSource(LinkFromSrc, *DGV, *GV2))
      return;
    if (!LinkFromSrc)
      continue;
    if (shouldInternalizeLinkedSymbols())
      Internalize.insert(GV2->getName());
    Add(*GV2);
  }
}
Beispiel #5
0
static bool shouldInternalize(const GlobalValue &GV,
                              const std::set<std::string> &ExternalNames,
                              bool OnlyHidden) {
  if (OnlyHidden && !GV.hasHiddenVisibility())
    return false;

  // Function must be defined here
  if (GV.isDeclaration())
    return false;

  // Available externally is really just a "declaration with a body".
  if (GV.hasAvailableExternallyLinkage())
    return false;

  // Assume that dllexported symbols are referenced elsewhere
  if (GV.hasDLLExportStorageClass())
    return false;

  // Already has internal linkage
  if (GV.hasLocalLinkage())
    return false;

  // Marked to keep external?
  if (ExternalNames.count(GV.getName()))
    return false;

  return true;
}
Beispiel #6
0
void LTOCodeGenerator::
applyRestriction(GlobalValue &GV,
                 std::vector<const char*> &MustPreserveList,
                 std::vector<const char*> &DSOList,
                 SmallPtrSet<GlobalValue*, 8> &AsmUsed,
                 Mangler &Mangler) {
  SmallString<64> Buffer;
  Mangler.getNameWithPrefix(Buffer, &GV, false);

  if (GV.isDeclaration())
    return;
  if (MustPreserveSymbols.count(Buffer))
    MustPreserveList.push_back(GV.getName().data());
  if (DSOSymbols.count(Buffer))
    DSOList.push_back(GV.getName().data());
  if (AsmUndefinedRefs.count(Buffer))
    AsmUsed.insert(&GV);
}
Beispiel #7
0
Module * llvmutil_extractmodule(Module * OrigMod, TargetMachine * TM, std::vector<llvm::GlobalValue*> * livevalues, std::vector<std::string> * symbolnames, bool internalizeandoptimize) {
        assert(symbolnames == NULL || livevalues->size() == symbolnames->size());
        ValueToValueMapTy VMap;
        #if LLVM_VERSION >= 34
        Module * M = llvmutil_extractmodulewithproperties(OrigMod->getModuleIdentifier(), OrigMod, (llvm::GlobalValue **)&(*livevalues)[0], livevalues->size(), AlwaysCopy, NULL, VMap);
        #else
        Module * M = CloneModule(OrigMod, VMap);
        internalizeandoptimize = true; //we need to do this regardless of the input because it is the only way we can extract just the needed functions from the module
        #endif

        //rename values to symbolsnames
        std::vector<const char *> names;
        for(size_t i = 0; i < livevalues->size(); i++) {
            GlobalValue * fn = cast<GlobalValue>(VMap[(*livevalues)[i]]);
            const std::string & name = (*symbolnames)[i];
            GlobalValue * gv = M->getNamedValue(name);
            if(gv) { //if there is already a symbol with this name, rename it
                gv->setName(Twine((*symbolnames)[i],"_renamed"));
            }
            fn->setName(name); //and set our function to this name
            assert(fn->getName() == name);
            names.push_back(name.c_str()); //internalize pass has weird interface, so we need to copy the names here
        }
        
        if (!internalizeandoptimize)
            return M;
    
        //at this point we run optimizations on the module
        //first internalize all functions not mentioned in "names" using an internalize pass and then perform 
        //standard optimizations
        PassManager MPM;
        llvmutil_addtargetspecificpasses(&MPM, TM);
    
        MPM.add(createVerifierPass()); //make sure we haven't messed stuff up yet
        MPM.add(createInternalizePass(names));
        MPM.add(createGlobalDCEPass()); //run this early since anything not in the table of exported functions is still in this module
                                         //this will remove dead functions
        
        PassManagerBuilder PMB;
        PMB.OptLevel = 3;
        PMB.SizeLevel = 0;
    
#if LLVM_VERSION >= 35
        PMB.LoopVectorize = true;
        PMB.SLPVectorize = true;
#endif

        PMB.populateModulePassManager(MPM);
    
        MPM.run(*M);
    

        return M;
}
Beispiel #8
0
void Variables::changeGlobal(Change* change, Module &module) {

  GlobalValue* oldTarget = dyn_cast<GlobalValue>(change->getValue());
  Type* oldType = oldTarget->getType()->getElementType();
  Type* newType = change->getType()[0];
  errs() << "Changing the precision of variable \"" << oldTarget->getName() << "\" from " << *oldType << " to " << *newType << ".\n";

  if (diffTypes(oldType, newType)) {      
    Constant *initializer;
    GlobalVariable* newTarget;

    if (PointerType *newPointerType = dyn_cast<PointerType>(newType)) {
      initializer = ConstantPointerNull::get(newPointerType);
      newTarget = new GlobalVariable(module, newType, false, GlobalValue::CommonLinkage, initializer, "");
    }
    else if (ArrayType * atype = dyn_cast<ArrayType>(newType)) {

      // preparing initializer
      Type *temp = Type::getFloatTy(module.getContext());
      vector<Constant*> operands;
      operands.push_back(ConstantFP::get(temp, 0));
      ArrayRef<Constant*> *arrayRef = new ArrayRef<Constant*>(operands);
      initializer = ConstantArray::get(atype, *arrayRef);

      newTarget = new GlobalVariable(module, newType, false, GlobalValue::CommonLinkage, initializer, "");
    }
    else {
      initializer = ConstantFP::get(newType, 0);
      newTarget = new GlobalVariable(module, newType, false, GlobalValue::CommonLinkage, initializer, "");
    }

    /*
    GlobalVariable* newTarget = new GlobalVariable(module, newType, false, GlobalValue::CommonLinkage, initializer, "");
    */

    unsigned alignment = getAlignment(newType);
    newTarget->setAlignment(alignment);

    newTarget->takeName(oldTarget);
    
    // iterating through instructions using old AllocaInst
    Value::use_iterator it = oldTarget->use_begin();
    for(; it != oldTarget->use_end(); it++) {
      Transformer::transform(it, newTarget, oldTarget, newType, oldType, alignment);
    }	  
    //oldTarget->eraseFromParent();
  }
  else {
    errs() << "No changes required.\n";
  }
  return;
}
Beispiel #9
0
static void DumpSymbolNameForGlobalValue(GlobalValue &GV) {
  const std::string SymbolAddrStr = "        "; // Not used yet...
  char TypeChar = TypeCharForSymbol (GV);
  if ((TypeChar != 'U') && UndefinedOnly)
    return;
  if ((TypeChar == 'U') && DefinedOnly)
    return;
  if (GV.hasLocalLinkage () && ExternalOnly)
    return;
  if (OutputFormat == posix) {
    std::cout << GV.getName () << " " << TypeCharForSymbol (GV) << " "
              << SymbolAddrStr << "\n";
  } else if (OutputFormat == bsd) {
    std::cout << SymbolAddrStr << " " << TypeCharForSymbol (GV) << " "
              << GV.getName () << "\n";
  } else if (OutputFormat == sysv) {
    std::string PaddedName (GV.getName ());
    while (PaddedName.length () < 20)
      PaddedName += " ";
    std::cout << PaddedName << "|" << SymbolAddrStr << "|   "
              << TypeCharForSymbol (GV)
              << "  |                  |      |     |\n";
  }
}
Beispiel #10
0
static void DumpSymbolNameForGlobalValue(GlobalValue &GV) {
  // Private linkage and available_externally linkage don't exist in symtab.
  if (GV.hasPrivateLinkage() ||
      GV.hasLinkerPrivateLinkage() ||
      GV.hasLinkerPrivateWeakLinkage() ||
      GV.hasAvailableExternallyLinkage())
    return;
  char TypeChar = TypeCharForSymbol(GV);
  if (GV.hasLocalLinkage () && ExternalOnly)
    return;

  NMSymbol s;
  s.Address = object::UnknownAddressOrSize;
  s.Size = object::UnknownAddressOrSize;
  s.TypeChar = TypeChar;
  s.Name     = GV.getName();
  SymbolList.push_back(s);
}
Beispiel #11
0
void ModuleLinker::addLazyFor(GlobalValue &GV, IRMover::ValueAdder Add) {
  // Add these to the internalize list
  if (!GV.hasLinkOnceLinkage())
    return;

  if (shouldInternalizeLinkedSymbols())
    Internalize.insert(GV.getName());
  Add(GV);

  const Comdat *SC = GV.getComdat();
  if (!SC)
    return;
  for (GlobalValue *GV2 : ComdatMembers[SC]) {
    if (!GV2->hasLocalLinkage() && shouldInternalizeLinkedSymbols())
      Internalize.insert(GV2->getName());
    Add(*GV2);
  }
}
bool UnsafeTypeCastingCheck::doInitialization(llvm::Module &mod) { 
  errs() << "initialization... \n"; 
  
  for (Module::global_iterator git = mod.global_begin() ;
       git != mod.global_end() ; 
       git++) {
    GlobalValue *gv = dyn_cast<GlobalValue>(git);
    string gv_name = gv->getName().str(); 
    if (gv_name.compare("blockDim") == 0 || 
	gv_name.compare("gridDim") == 0 || 
	gv_name.compare("blockIdx") == 0 || 
	gv_name.compare("threadIdx") == 0) {
      setPointedType(gv, UINT_UT); 
    }
  }

  // get utcc_assert function call (assertion) 
  code_modified = false; 
  assert_func = mod.getFunction("utcc_assert"); 
  assert(assert_func != NULL); 

  return false; 
}
Beispiel #13
0
void ModuleLinker::addLazyFor(GlobalValue &GV, IRMover::ValueAdder Add) {
    // Add these to the internalize list
    if (!GV.hasLinkOnceLinkage())
        return;

    if (shouldInternalizeLinkedSymbols())
        Internalize.insert(GV.getName());
    Add(GV);

    const Comdat *SC = GV.getComdat();
    if (!SC)
        return;
    for (GlobalValue *GV2 : LazyComdatMembers[SC]) {
        GlobalValue *DGV = getLinkedToGlobal(GV2);
        bool LinkFromSrc = true;
        if (DGV && shouldLinkFromSource(LinkFromSrc, *DGV, *GV2))
            return;
        if (!LinkFromSrc)
            continue;
        if (shouldInternalizeLinkedSymbols())
            Internalize.insert(GV2->getName());
        Add(*GV2);
    }
}
Beispiel #14
0
void BitcodeCompiler::add(BitcodeFile &F) {
  std::unique_ptr<IRObjectFile> Obj = std::move(F.Obj);
  std::vector<GlobalValue *> Keep;
  unsigned BodyIndex = 0;
  ArrayRef<Symbol *> Syms = F.getSymbols();

  Module &M = Obj->getModule();
  if (M.getDataLayoutStr().empty())
    fatal("invalid bitcode file: " + F.getName() + " has no datalayout");

  // Discard non-compatible debug infos if necessary.
  M.materializeMetadata();
  UpgradeDebugInfo(M);

  // If a symbol appears in @llvm.used, the linker is required
  // to treat the symbol as there is a reference to the symbol
  // that it cannot see. Therefore, we can't internalize.
  SmallPtrSet<GlobalValue *, 8> Used;
  collectUsedGlobalVariables(M, Used, /* CompilerUsed */ false);

  for (const BasicSymbolRef &Sym : Obj->symbols()) {
    uint32_t Flags = Sym.getFlags();
    GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());
    if (GV && GV->hasAppendingLinkage())
      Keep.push_back(GV);
    if (BitcodeFile::shouldSkip(Flags))
      continue;
    Symbol *S = Syms[BodyIndex++];
    if (Flags & BasicSymbolRef::SF_Undefined) {
      handleUndefinedAsmRefs(Sym, GV, AsmUndefinedRefs);
      continue;
    }
    auto *B = dyn_cast<DefinedBitcode>(S->body());
    if (!B || B->File != &F)
      continue;

    // We collect the set of symbols we want to internalize here
    // and change the linkage after the IRMover executed, i.e. after
    // we imported the symbols and satisfied undefined references
    // to it. We can't just change linkage here because otherwise
    // the IRMover will just rename the symbol.
    if (GV && shouldInternalize(Used, S, GV))
      InternalizedSyms.insert(GV->getName());

    // At this point we know that either the combined LTO object will provide a
    // definition of a symbol, or we will internalize it. In either case, we
    // need to undefine the symbol. In the former case, the real definition
    // needs to be able to replace the original definition without conflicting.
    // In the latter case, we need to allow the combined LTO object to provide a
    // definition with the same name, for example when doing parallel codegen.
    undefine(S);

    if (!GV)
      // Module asm symbol.
      continue;

    switch (GV->getLinkage()) {
    default:
      break;
    case llvm::GlobalValue::LinkOnceAnyLinkage:
      GV->setLinkage(GlobalValue::WeakAnyLinkage);
      break;
    case llvm::GlobalValue::LinkOnceODRLinkage:
      GV->setLinkage(GlobalValue::WeakODRLinkage);
      break;
    }

    Keep.push_back(GV);
  }

  if (Error E = Mover.move(Obj->takeModule(), Keep,
                           [](GlobalValue &, IRMover::ValueAdder) {})) {
    handleAllErrors(std::move(E), [&](const llvm::ErrorInfoBase &EIB) {
      fatal("failed to link module " + F.getName() + ": " + EIB.message());
    });
  }
}
Beispiel #15
0
bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
                                        const GlobalValue &Dest,
                                        const GlobalValue &Src) {

    // Should we unconditionally use the Src?
    if (shouldOverrideFromSrc()) {
        LinkFromSrc = true;
        return false;
    }

    // We always have to add Src if it has appending linkage.
    if (Src.hasAppendingLinkage()) {
        // Should have prevented importing for appending linkage in linkIfNeeded.
        assert(!isPerformingImport());
        LinkFromSrc = true;
        return false;
    }

    bool SrcIsDeclaration = Src.isDeclarationForLinker();
    bool DestIsDeclaration = Dest.isDeclarationForLinker();

    if (isPerformingImport()) {
        if (isa<Function>(&Src)) {
            // For functions, LinkFromSrc iff this is a function requested
            // for importing. For variables, decide below normally.
            LinkFromSrc = GlobalsToImport->count(&Src);
            return false;
        }

        // Check if this is an alias with an already existing definition
        // in Dest, which must have come from a prior importing pass from
        // the same Src module. Unlike imported function and variable
        // definitions, which are imported as available_externally and are
        // not definitions for the linker, that is not a valid linkage for
        // imported aliases which must be definitions. Simply use the existing
        // Dest copy.
        if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
            assert(isa<GlobalAlias>(&Dest));
            LinkFromSrc = false;
            return false;
        }
    }

    if (SrcIsDeclaration) {
        // If Src is external or if both Src & Dest are external..  Just link the
        // external globals, we aren't adding anything.
        if (Src.hasDLLImportStorageClass()) {
            // If one of GVs is marked as DLLImport, result should be dllimport'ed.
            LinkFromSrc = DestIsDeclaration;
            return false;
        }
        // If the Dest is weak, use the source linkage.
        if (Dest.hasExternalWeakLinkage()) {
            LinkFromSrc = true;
            return false;
        }
        // Link an available_externally over a declaration.
        LinkFromSrc = !Src.isDeclaration() && Dest.isDeclaration();
        return false;
    }

    if (DestIsDeclaration) {
        // If Dest is external but Src is not:
        LinkFromSrc = true;
        return false;
    }

    if (Src.hasCommonLinkage()) {
        if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
            LinkFromSrc = true;
            return false;
        }

        if (!Dest.hasCommonLinkage()) {
            LinkFromSrc = false;
            return false;
        }

        const DataLayout &DL = Dest.getParent()->getDataLayout();
        uint64_t DestSize = DL.getTypeAllocSize(Dest.getValueType());
        uint64_t SrcSize = DL.getTypeAllocSize(Src.getValueType());
        LinkFromSrc = SrcSize > DestSize;
        return false;
    }

    if (Src.isWeakForLinker()) {
        assert(!Dest.hasExternalWeakLinkage());
        assert(!Dest.hasAvailableExternallyLinkage());

        if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
            LinkFromSrc = true;
            return false;
        }

        LinkFromSrc = false;
        return false;
    }

    if (Dest.isWeakForLinker()) {
        assert(Src.hasExternalLinkage());
        LinkFromSrc = true;
        return false;
    }

    assert(!Src.hasExternalWeakLinkage());
    assert(!Dest.hasExternalWeakLinkage());
    assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
           "Unexpected linkage type!");
    return emitError("Linking globals named '" + Src.getName() +
                     "': symbol multiply defined!");
}
Beispiel #16
0
static std::unique_ptr<Module>
getModuleForFile(LLVMContext &Context, claimed_file &F,
                 ld_plugin_input_file &Info, raw_fd_ostream *ApiFile,
                 StringSet<> &Internalize, StringSet<> &Maybe) {

  if (get_symbols(F.handle, F.syms.size(), F.syms.data()) != LDPS_OK)
    message(LDPL_FATAL, "Failed to get symbol information");

  const void *View;
  if (get_view(F.handle, &View) != LDPS_OK)
    message(LDPL_FATAL, "Failed to get a view of file");

  MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
                            Info.name);
  ErrorOr<std::unique_ptr<object::IRObjectFile>> ObjOrErr =
      object::IRObjectFile::create(BufferRef, Context);

  if (std::error_code EC = ObjOrErr.getError())
    message(LDPL_FATAL, "Could not read bitcode from file : %s",
            EC.message().c_str());

  object::IRObjectFile &Obj = **ObjOrErr;

  Module &M = Obj.getModule();

  M.materializeMetadata();
  UpgradeDebugInfo(M);

  SmallPtrSet<GlobalValue *, 8> Used;
  collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);

  DenseSet<GlobalValue *> Drop;
  std::vector<GlobalAlias *> KeptAliases;

  unsigned SymNum = 0;
  for (auto &ObjSym : Obj.symbols()) {
    if (shouldSkip(ObjSym.getFlags()))
      continue;
    ld_plugin_symbol &Sym = F.syms[SymNum];
    ++SymNum;

    ld_plugin_symbol_resolution Resolution =
        (ld_plugin_symbol_resolution)Sym.resolution;

    if (options::generate_api_file)
      *ApiFile << Sym.name << ' ' << getResolutionName(Resolution) << '\n';

    GlobalValue *GV = Obj.getSymbolGV(ObjSym.getRawDataRefImpl());
    if (!GV) {
      freeSymName(Sym);
      continue; // Asm symbol.
    }

    if (Resolution != LDPR_PREVAILING_DEF_IRONLY && GV->hasCommonLinkage()) {
      // Common linkage is special. There is no single symbol that wins the
      // resolution. Instead we have to collect the maximum alignment and size.
      // The IR linker does that for us if we just pass it every common GV.
      // We still have to keep track of LDPR_PREVAILING_DEF_IRONLY so we
      // internalize once the IR linker has done its job.
      freeSymName(Sym);
      continue;
    }

    switch (Resolution) {
    case LDPR_UNKNOWN:
      llvm_unreachable("Unexpected resolution");

    case LDPR_RESOLVED_IR:
    case LDPR_RESOLVED_EXEC:
    case LDPR_RESOLVED_DYN:
      assert(GV->isDeclarationForLinker());
      break;

    case LDPR_UNDEF:
      if (!GV->isDeclarationForLinker()) {
        assert(GV->hasComdat());
        Drop.insert(GV);
      }
      break;

    case LDPR_PREVAILING_DEF_IRONLY: {
      keepGlobalValue(*GV, KeptAliases);
      if (!Used.count(GV)) {
        // Since we use the regular lib/Linker, we cannot just internalize GV
        // now or it will not be copied to the merged module. Instead we force
        // it to be copied and then internalize it.
        Internalize.insert(GV->getName());
      }
      break;
    }

    case LDPR_PREVAILING_DEF:
      keepGlobalValue(*GV, KeptAliases);
      break;

    case LDPR_PREEMPTED_IR:
      // Gold might have selected a linkonce_odr and preempted a weak_odr.
      // In that case we have to make sure we don't end up internalizing it.
      if (!GV->isDiscardableIfUnused())
        Maybe.erase(GV->getName());

      // fall-through
    case LDPR_PREEMPTED_REG:
      Drop.insert(GV);
      break;

    case LDPR_PREVAILING_DEF_IRONLY_EXP: {
      // We can only check for address uses after we merge the modules. The
      // reason is that this GV might have a copy in another module
      // and in that module the address might be significant, but that
      // copy will be LDPR_PREEMPTED_IR.
      if (GV->hasLinkOnceODRLinkage())
        Maybe.insert(GV->getName());
      keepGlobalValue(*GV, KeptAliases);
      break;
    }
    }

    freeSymName(Sym);
  }

  ValueToValueMapTy VM;
  LocalValueMaterializer Materializer(Drop);
  for (GlobalAlias *GA : KeptAliases) {
    // Gold told us to keep GA. It is possible that a GV usied in the aliasee
    // expression is being dropped. If that is the case, that GV must be copied.
    Constant *Aliasee = GA->getAliasee();
    Constant *Replacement = mapConstantToLocalCopy(Aliasee, VM, &Materializer);
    GA->setAliasee(Replacement);
  }

  for (auto *GV : Drop)
    drop(*GV);

  return Obj.takeModule();
}
void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {

  ValueInfo VI;
  if (GV.hasName()) {
    VI = ImportIndex.getValueInfo(GV.getGUID());
    // Set synthetic function entry counts.
    if (VI && ImportIndex.hasSyntheticEntryCounts()) {
      if (Function *F = dyn_cast<Function>(&GV)) {
        if (!F->isDeclaration()) {
          for (auto &S : VI.getSummaryList()) {
            FunctionSummary *FS = dyn_cast<FunctionSummary>(S->getBaseObject());
            if (FS->modulePath() == M.getModuleIdentifier()) {
              F->setEntryCount(Function::ProfileCount(FS->entryCount(),
                                                      Function::PCT_Synthetic));
              break;
            }
          }
        }
      }
    }
    // Check the summaries to see if the symbol gets resolved to a known local
    // definition.
    if (VI && VI.isDSOLocal()) {
      GV.setDSOLocal(true);
      if (GV.hasDLLImportStorageClass())
        GV.setDLLStorageClass(GlobalValue::DefaultStorageClass);
    }
  }

  // Mark read-only variables which can be imported with specific attribute.
  // We can't internalize them now because IRMover will fail to link variable
  // definitions to their external declarations during ThinLTO import. We'll
  // internalize read-only variables later, after import is finished.
  // See internalizeImmutableGVs.
  //
  // If global value dead stripping is not enabled in summary then
  // propagateConstants hasn't been run. We can't internalize GV
  // in such case.
  if (!GV.isDeclaration() && VI && ImportIndex.withGlobalValueDeadStripping()) {
    const auto &SL = VI.getSummaryList();
    auto *GVS = SL.empty() ? nullptr : dyn_cast<GlobalVarSummary>(SL[0].get());
    if (GVS && GVS->isReadOnly())
      cast<GlobalVariable>(&GV)->addAttribute("thinlto-internalize");
  }

  bool DoPromote = false;
  if (GV.hasLocalLinkage() &&
      ((DoPromote = shouldPromoteLocalToGlobal(&GV)) || isPerformingImport())) {
    // Save the original name string before we rename GV below.
    auto Name = GV.getName().str();
    // Once we change the name or linkage it is difficult to determine
    // again whether we should promote since shouldPromoteLocalToGlobal needs
    // to locate the summary (based on GUID from name and linkage). Therefore,
    // use DoPromote result saved above.
    GV.setName(getName(&GV, DoPromote));
    GV.setLinkage(getLinkage(&GV, DoPromote));
    if (!GV.hasLocalLinkage())
      GV.setVisibility(GlobalValue::HiddenVisibility);

    // If we are renaming a COMDAT leader, ensure that we record the COMDAT
    // for later renaming as well. This is required for COFF.
    if (const auto *C = GV.getComdat())
      if (C->getName() == Name)
        RenamedComdats.try_emplace(C, M.getOrInsertComdat(GV.getName()));
  } else
    GV.setLinkage(getLinkage(&GV, /* DoPromote */ false));

  // Remove functions imported as available externally defs from comdats,
  // as this is a declaration for the linker, and will be dropped eventually.
  // It is illegal for comdats to contain declarations.
  auto *GO = dyn_cast<GlobalObject>(&GV);
  if (GO && GO->isDeclarationForLinker() && GO->hasComdat()) {
    // The IRMover should not have placed any imported declarations in
    // a comdat, so the only declaration that should be in a comdat
    // at this point would be a definition imported as available_externally.
    assert(GO->hasAvailableExternallyLinkage() &&
           "Expected comdat on definition (possibly available external)");
    GO->setComdat(nullptr);
  }
}
Beispiel #18
0
bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
                                        const GlobalValue &Dest,
                                        const GlobalValue &Src) {

  // Should we unconditionally use the Src?
  if (shouldOverrideFromSrc()) {
    LinkFromSrc = true;
    return false;
  }

  // We always have to add Src if it has appending linkage.
  if (Src.hasAppendingLinkage()) {
    // Should have prevented importing for appending linkage in linkIfNeeded.
    assert(!isPerformingImport());
    LinkFromSrc = true;
    return false;
  }

  if (isPerformingImport()) {
    // LinkFromSrc iff this is a global requested for importing.
    LinkFromSrc = GlobalsToImport->count(&Src);
    return false;
  }

  bool SrcIsDeclaration = Src.isDeclarationForLinker();
  bool DestIsDeclaration = Dest.isDeclarationForLinker();

  if (SrcIsDeclaration) {
    // If Src is external or if both Src & Dest are external..  Just link the
    // external globals, we aren't adding anything.
    if (Src.hasDLLImportStorageClass()) {
      // If one of GVs is marked as DLLImport, result should be dllimport'ed.
      LinkFromSrc = DestIsDeclaration;
      return false;
    }
    // If the Dest is weak, use the source linkage.
    if (Dest.hasExternalWeakLinkage()) {
      LinkFromSrc = true;
      return false;
    }
    // Link an available_externally over a declaration.
    LinkFromSrc = !Src.isDeclaration() && Dest.isDeclaration();
    return false;
  }

  if (DestIsDeclaration) {
    // If Dest is external but Src is not:
    LinkFromSrc = true;
    return false;
  }

  if (Src.hasCommonLinkage()) {
    if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
      LinkFromSrc = true;
      return false;
    }

    if (!Dest.hasCommonLinkage()) {
      LinkFromSrc = false;
      return false;
    }

    const DataLayout &DL = Dest.getParent()->getDataLayout();
    uint64_t DestSize = DL.getTypeAllocSize(Dest.getValueType());
    uint64_t SrcSize = DL.getTypeAllocSize(Src.getValueType());
    LinkFromSrc = SrcSize > DestSize;
    return false;
  }

  if (Src.isWeakForLinker()) {
    assert(!Dest.hasExternalWeakLinkage());
    assert(!Dest.hasAvailableExternallyLinkage());

    if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
      LinkFromSrc = true;
      return false;
    }

    LinkFromSrc = false;
    return false;
  }

  if (Dest.isWeakForLinker()) {
    assert(Src.hasExternalLinkage());
    LinkFromSrc = true;
    return false;
  }

  assert(!Src.hasExternalWeakLinkage());
  assert(!Dest.hasExternalWeakLinkage());
  assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
         "Unexpected linkage type!");
  return emitError("Linking globals named '" + Src.getName() +
                   "': symbol multiply defined!");
}
Beispiel #19
0
void BitcodeCompiler::add(BitcodeFile &F) {
  std::unique_ptr<IRObjectFile> Obj =
      check(IRObjectFile::create(F.MB, Context));
  std::vector<GlobalValue *> Keep;
  unsigned BodyIndex = 0;
  ArrayRef<SymbolBody *> Bodies = F.getSymbols();

  Module &M = Obj->getModule();
  if (M.getDataLayoutStr().empty())
    fatal("invalid bitcode file: " + F.getName() + " has no datalayout");

  // If a symbol appears in @llvm.used, the linker is required
  // to treat the symbol as there is a reference to the symbol
  // that it cannot see. Therefore, we can't internalize.
  SmallPtrSet<GlobalValue *, 8> Used;
  collectUsedGlobalVariables(M, Used, /* CompilerUsed */ false);

  for (const BasicSymbolRef &Sym : Obj->symbols()) {
    GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());
    // Ignore module asm symbols.
    if (!GV)
      continue;
    if (GV->hasAppendingLinkage()) {
      Keep.push_back(GV);
      continue;
    }
    if (BitcodeFile::shouldSkip(Sym))
      continue;
    SymbolBody *B = Bodies[BodyIndex++];
    if (!B || &B->repl() != B || !isa<DefinedBitcode>(B))
      continue;
    switch (GV->getLinkage()) {
    default:
      break;
    case llvm::GlobalValue::LinkOnceAnyLinkage:
      GV->setLinkage(GlobalValue::WeakAnyLinkage);
      break;
    case llvm::GlobalValue::LinkOnceODRLinkage:
      GV->setLinkage(GlobalValue::WeakODRLinkage);
      break;
    }

    // We collect the set of symbols we want to internalize here
    // and change the linkage after the IRMover executed, i.e. after
    // we imported the symbols and satisfied undefined references
    // to it. We can't just change linkage here because otherwise
    // the IRMover will just rename the symbol.
    // Shared libraries need to be handled slightly differently.
    // For now, let's be conservative and just never internalize
    // symbols when creating a shared library.
    if (!Config->Shared && !Config->ExportDynamic && !B->isUsedInRegularObj() &&
        !B->MustBeInDynSym)
      if (!Used.count(GV))
        InternalizedSyms.insert(GV->getName());

    Keep.push_back(GV);
  }

  Mover.move(Obj->takeModule(), Keep,
             [](GlobalValue &, IRMover::ValueAdder) {});
}
Beispiel #20
0
static std::unique_ptr<Module>
getModuleForFile(LLVMContext &Context, claimed_file &F, const void *View,
                 ld_plugin_input_file &Info, raw_fd_ostream *ApiFile,
                 StringSet<> &Internalize, StringSet<> &Maybe,
                 std::vector<GlobalValue *> &Keep,
                 StringMap<unsigned> &Realign) {
  MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
                            Info.name);
  ErrorOr<std::unique_ptr<object::IRObjectFile>> ObjOrErr =
      object::IRObjectFile::create(BufferRef, Context);

  if (std::error_code EC = ObjOrErr.getError())
    message(LDPL_FATAL, "Could not read bitcode from file : %s",
            EC.message().c_str());

  object::IRObjectFile &Obj = **ObjOrErr;

  Module &M = Obj.getModule();

  M.materializeMetadata();
  UpgradeDebugInfo(M);

  SmallPtrSet<GlobalValue *, 8> Used;
  collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);

  unsigned SymNum = 0;
  for (auto &ObjSym : Obj.symbols()) {
    GlobalValue *GV = Obj.getSymbolGV(ObjSym.getRawDataRefImpl());
    if (GV && GV->hasAppendingLinkage())
      Keep.push_back(GV);

    if (shouldSkip(ObjSym.getFlags()))
      continue;
    ld_plugin_symbol &Sym = F.syms[SymNum];
    ++SymNum;

    ld_plugin_symbol_resolution Resolution =
        (ld_plugin_symbol_resolution)Sym.resolution;

    if (options::generate_api_file)
      *ApiFile << Sym.name << ' ' << getResolutionName(Resolution) << '\n';

    if (!GV) {
      freeSymName(Sym);
      continue; // Asm symbol.
    }

    ResolutionInfo &Res = ResInfo[Sym.name];
    if (Resolution == LDPR_PREVAILING_DEF_IRONLY_EXP && !Res.IsLinkonceOdr)
      Resolution = LDPR_PREVAILING_DEF;

    // In ThinLTO mode change all prevailing resolutions to LDPR_PREVAILING_DEF.
    // For ThinLTO the IR files are compiled through the backend independently,
    // so we need to ensure that any prevailing linkonce copy will be emitted
    // into the object file by making it weak. Additionally, we can skip the
    // IRONLY handling for internalization, which isn't performed in ThinLTO
    // mode currently anyway.
    if (options::thinlto && (Resolution == LDPR_PREVAILING_DEF_IRONLY_EXP ||
                             Resolution == LDPR_PREVAILING_DEF_IRONLY))
      Resolution = LDPR_PREVAILING_DEF;

    GV->setUnnamedAddr(Res.UnnamedAddr);
    GV->setVisibility(Res.Visibility);

    // Override gold's resolution for common symbols. We want the largest
    // one to win.
    if (GV->hasCommonLinkage()) {
      if (Resolution == LDPR_PREVAILING_DEF_IRONLY)
        Res.CommonInternal = true;

      if (Resolution == LDPR_PREVAILING_DEF_IRONLY ||
          Resolution == LDPR_PREVAILING_DEF)
        Res.UseCommon = true;

      const DataLayout &DL = GV->getParent()->getDataLayout();
      uint64_t Size = DL.getTypeAllocSize(GV->getType()->getElementType());
      unsigned Align = GV->getAlignment();

      if (Res.UseCommon && Size >= Res.CommonSize) {
        // Take GV.
        if (Res.CommonInternal)
          Resolution = LDPR_PREVAILING_DEF_IRONLY;
        else
          Resolution = LDPR_PREVAILING_DEF;
        cast<GlobalVariable>(GV)->setAlignment(
            std::max(Res.CommonAlign, Align));
      } else {
        // Do not take GV, it's smaller than what we already have in the
        // combined module.
        Resolution = LDPR_PREEMPTED_IR;
        if (Align > Res.CommonAlign)
          // Need to raise the alignment though.
          Realign[Sym.name] = Align;
      }

      Res.CommonSize = std::max(Res.CommonSize, Size);
      Res.CommonAlign = std::max(Res.CommonAlign, Align);
    }

    switch (Resolution) {
    case LDPR_UNKNOWN:
      llvm_unreachable("Unexpected resolution");

    case LDPR_RESOLVED_IR:
    case LDPR_RESOLVED_EXEC:
    case LDPR_RESOLVED_DYN:
    case LDPR_PREEMPTED_IR:
    case LDPR_PREEMPTED_REG:
      break;

    case LDPR_UNDEF:
      if (!GV->isDeclarationForLinker())
        assert(GV->hasComdat());
      break;

    case LDPR_PREVAILING_DEF_IRONLY: {
      Keep.push_back(GV);
      // The IR linker has to be able to map this value to a declaration,
      // so we can only internalize after linking.
      if (!Used.count(GV))
        Internalize.insert(GV->getName());
      break;
    }

    case LDPR_PREVAILING_DEF:
      Keep.push_back(GV);
      // There is a non IR use, so we have to force optimizations to keep this.
      switch (GV->getLinkage()) {
      default:
        break;
      case GlobalValue::LinkOnceAnyLinkage:
        GV->setLinkage(GlobalValue::WeakAnyLinkage);
        break;
      case GlobalValue::LinkOnceODRLinkage:
        GV->setLinkage(GlobalValue::WeakODRLinkage);
        break;
      }
      break;

    case LDPR_PREVAILING_DEF_IRONLY_EXP: {
      // We can only check for address uses after we merge the modules. The
      // reason is that this GV might have a copy in another module
      // and in that module the address might be significant, but that
      // copy will be LDPR_PREEMPTED_IR.
      Maybe.insert(GV->getName());
      Keep.push_back(GV);
      break;
    }
    }

    freeSymName(Sym);
  }

  return Obj.takeModule();
}
Beispiel #21
0
bool InternalizePass::runOnModule(Module &M) {
  CallGraphWrapperPass *CGPass = getAnalysisIfAvailable<CallGraphWrapperPass>();
  CallGraph *CG = CGPass ? &CGPass->getCallGraph() : 0;
  CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0;
  bool Changed = false;

  SmallPtrSet<GlobalValue *, 8> Used;
  collectUsedGlobalVariables(M, Used, false);

  // We must assume that globals in llvm.used have a reference that not even
  // the linker can see, so we don't internalize them.
  // For llvm.compiler.used the situation is a bit fuzzy. The assembler and
  // linker can drop those symbols. If this pass is running as part of LTO,
  // one might think that it could just drop llvm.compiler.used. The problem
  // is that even in LTO llvm doesn't see every reference. For example,
  // we don't see references from function local inline assembly. To be
  // conservative, we internalize symbols in llvm.compiler.used, but we
  // keep llvm.compiler.used so that the symbol is not deleted by llvm.
  for (SmallPtrSet<GlobalValue *, 8>::iterator I = Used.begin(), E = Used.end();
       I != E; ++I) {
    GlobalValue *V = *I;
    ExternalNames.insert(V->getName());
  }

  // Mark all functions not in the api as internal.
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
    if (!shouldInternalize(*I, ExternalNames, OnlyHidden))
      continue;

    I->setLinkage(GlobalValue::InternalLinkage);

    if (ExternalNode)
      // Remove a callgraph edge from the external node to this function.
      ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);

    Changed = true;
    ++NumFunctions;
    DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n");
  }

  // Never internalize the llvm.used symbol.  It is used to implement
  // attribute((used)).
  // FIXME: Shouldn't this just filter on llvm.metadata section??
  ExternalNames.insert("llvm.used");
  ExternalNames.insert("llvm.compiler.used");

  // Never internalize anchors used by the machine module info, else the info
  // won't find them.  (see MachineModuleInfo.)
  ExternalNames.insert("llvm.global_ctors");
  ExternalNames.insert("llvm.global_dtors");
  ExternalNames.insert("llvm.global.annotations");

  // Never internalize symbols code-gen inserts.
  // FIXME: We should probably add this (and the __stack_chk_guard) via some
  // type of call-back in CodeGen.
  ExternalNames.insert("__stack_chk_fail");
  ExternalNames.insert("__stack_chk_guard");

  // Mark all global variables with initializers that are not in the api as
  // internal as well.
  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I) {
    if (!shouldInternalize(*I, ExternalNames, OnlyHidden))
      continue;

    I->setLinkage(GlobalValue::InternalLinkage);
    Changed = true;
    ++NumGlobals;
    DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n");
  }

  // Mark all aliases that are not in the api as internal as well.
  for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
       I != E; ++I) {
    if (!shouldInternalize(*I, ExternalNames, OnlyHidden))
      continue;

    I->setLinkage(GlobalValue::InternalLinkage);
    Changed = true;
    ++NumAliases;
    DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n");
  }

  return Changed;
}
Beispiel #22
0
std::unique_ptr<llvm::Module>
klee::linkModules(std::vector<std::unique_ptr<llvm::Module>> &modules,
                  llvm::StringRef entryFunction, std::string &errorMsg) {
  assert(!modules.empty() && "modules list should not be empty");

  if (entryFunction.empty()) {
    // If no entry function is provided, link all modules together into one
    std::unique_ptr<llvm::Module> composite = std::move(modules.back());
    modules.pop_back();

    // Just link all modules together
    for (auto &module : modules) {
      if (linkTwoModules(composite.get(), std::move(module), errorMsg))
        continue;

      // Linking failed
      errorMsg = "Linking archive module with composite failed:" + errorMsg;
      return nullptr;
    }

    // clean up every module as we already linked in every module
    modules.clear();
    return composite;
  }

  // Starting from the module containing the entry function, resolve unresolved
  // dependencies recursively


  // search for the module containing the entry function
  std::unique_ptr<llvm::Module> composite;
  for (auto &module : modules) {
    if (!module || !module->getNamedValue(entryFunction))
      continue;
    if (composite) {
      errorMsg =
          "Function " + entryFunction.str() +
          " defined in different modules (" + module->getModuleIdentifier() +
          " already defined in: " + composite->getModuleIdentifier() + ")";
      return nullptr;
    }
    composite = std::move(module);
  }

  // fail if not found
  if (!composite) {
    errorMsg = "'" + entryFunction.str() + "' function not found in module.";
    return nullptr;
  }

  while (true) {
    std::set<std::string> undefinedSymbols;
    GetAllUndefinedSymbols(composite.get(), undefinedSymbols);

    // Stop in nothing is undefined
    if (undefinedSymbols.empty())
      break;

    bool merged = false;
    for (auto &module : modules) {
      if (!module)
        continue;

      for (auto symbol : undefinedSymbols) {
        GlobalValue *GV =
            dyn_cast_or_null<GlobalValue>(module->getNamedValue(symbol));
        if (!GV || GV->isDeclaration())
          continue;

        // Found symbol, therefore merge in module
        KLEE_DEBUG_WITH_TYPE("klee_linker",
                             dbgs() << "Found " << GV->getName() << " in "
                                    << module->getModuleIdentifier() << "\n");
        if (linkTwoModules(composite.get(), std::move(module), errorMsg)) {
          module = nullptr;
          merged = true;
          break;
        }
        // Linking failed
        errorMsg = "Linking archive module with composite failed:" + errorMsg;
        return nullptr;
      }
    }
    if (!merged)
      break;
  }

  // Condense the module array
  std::vector<std::unique_ptr<llvm::Module>> LeftoverModules;
  for (auto &module : modules) {
    if (module)
      LeftoverModules.emplace_back(std::move(module));
  }

  modules.swap(LeftoverModules);
  return composite;
}