C++ GlobalVariable::getName方法代码示例

bool GenericToNVVM::runOnModule(Module &M) {
  // Create a clone of each global variable that has the default address space.
  // The clone is created with the global address space  specifier, and the pair
  // of original global variable and its clone is placed in the GVMap for later
  // use.

  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E;) {
    GlobalVariable *GV = I++;
    if (GV->getType()->getAddressSpace() == llvm::ADDRESS_SPACE_GENERIC &&
        !llvm::isTexture(*GV) && !llvm::isSurface(*GV) &&
        !GV->getName().startswith("llvm.")) {
      GlobalVariable *NewGV = new GlobalVariable(
          M, GV->getType()->getElementType(), GV->isConstant(),
          GV->getLinkage(),
          GV->hasInitializer() ? GV->getInitializer() : nullptr,
          "", GV, GV->getThreadLocalMode(), llvm::ADDRESS_SPACE_GLOBAL);
      NewGV->copyAttributesFrom(GV);
      GVMap[GV] = NewGV;
    }
  }

  // Return immediately, if every global variable has a specific address space
  // specifier.
  if (GVMap.empty()) {
    return false;
  }

  // Walk through the instructions in function defitinions, and replace any use
  // of original global variables in GVMap with a use of the corresponding
  // copies in GVMap.  If necessary, promote constants to instructions.
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
    if (I->isDeclaration()) {
      continue;
    }
    IRBuilder<> Builder(I->getEntryBlock().getFirstNonPHIOrDbg());
    for (Function::iterator BBI = I->begin(), BBE = I->end(); BBI != BBE;
         ++BBI) {
      for (BasicBlock::iterator II = BBI->begin(), IE = BBI->end(); II != IE;
           ++II) {
        for (unsigned i = 0, e = II->getNumOperands(); i < e; ++i) {
          Value *Operand = II->getOperand(i);
          if (isa<Constant>(Operand)) {
            II->setOperand(
                i, remapConstant(&M, I, cast<Constant>(Operand), Builder));
          }
        }
      }
    }
    ConstantToValueMap.clear();
  }

  // Walk through the metadata section and update the debug information
  // associated with the global variables in the default address space.
  for (Module::named_metadata_iterator I = M.named_metadata_begin(),
                                       E = M.named_metadata_end();
       I != E; I++) {
    remapNamedMDNode(&M, I);
  }

  // Walk through the global variable  initializers, and replace any use of
  // original global variables in GVMap with a use of the corresponding copies
  // in GVMap.  The copies need to be bitcast to the original global variable
  // types, as we cannot use cvta in global variable initializers.
  for (GVMapTy::iterator I = GVMap.begin(), E = GVMap.end(); I != E;) {
    GlobalVariable *GV = I->first;
    GlobalVariable *NewGV = I->second;
    ++I;
    Constant *BitCastNewGV = ConstantExpr::getPointerCast(NewGV, GV->getType());
    // At this point, the remaining uses of GV should be found only in global
    // variable initializers, as other uses have been already been removed
    // while walking through the instructions in function definitions.
    for (Value::use_iterator UI = GV->use_begin(), UE = GV->use_end();
         UI != UE;)
      (UI++)->set(BitCastNewGV);
    std::string Name = GV->getName();
    GV->removeDeadConstantUsers();
    GV->eraseFromParent();
    NewGV->setName(Name);
  }
  GVMap.clear();

  return true;
}

// This function replaces all global variables with new variables that have
// trailing redzones. It also creates a function that poisons
// redzones and inserts this function into llvm.global_ctors.
bool AddressSanitizer::insertGlobalRedzones(Module &M) {
  SmallVector<GlobalVariable *, 16> GlobalsToChange;

  for (Module::GlobalListType::iterator G = M.getGlobalList().begin(),
       E = M.getGlobalList().end(); G != E; ++G) {
    Type *Ty = cast<PointerType>(G->getType())->getElementType();
    DEBUG(dbgs() << "GLOBAL: " << *G);

    if (!Ty->isSized()) continue;
    if (!G->hasInitializer()) continue;
    // Touch only those globals that will not be defined in other modules.
    // Don't handle ODR type linkages since other modules may be built w/o asan.
    if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
        G->getLinkage() != GlobalVariable::PrivateLinkage &&
        G->getLinkage() != GlobalVariable::InternalLinkage)
      continue;
    // Two problems with thread-locals:
    //   - The address of the main thread's copy can't be computed at link-time.
    //   - Need to poison all copies, not just the main thread's one.
    if (G->isThreadLocal())
      continue;
    // For now, just ignore this Alloca if the alignment is large.
    if (G->getAlignment() > RedzoneSize) continue;

    // Ignore all the globals with the names starting with "\01L_OBJC_".
    // Many of those are put into the .cstring section. The linker compresses
    // that section by removing the spare \0s after the string terminator, so
    // our redzones get broken.
    if ((G->getName().find("\01L_OBJC_") == 0) ||
        (G->getName().find("\01l_OBJC_") == 0)) {
      DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
      continue;
    }

    if (G->hasSection()) {
      StringRef Section(G->getSection());
      // Ignore the globals from the __OBJC section. The ObjC runtime assumes
      // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
      // them.
      if ((Section.find("__OBJC,") == 0) ||
          (Section.find("__DATA, __objc_") == 0)) {
        DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
        continue;
      }
      // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
      // Constant CFString instances are compiled in the following way:
      //  -- the string buffer is emitted into
      //     __TEXT,__cstring,cstring_literals
      //  -- the constant NSConstantString structure referencing that buffer
      //     is placed into __DATA,__cfstring
      // Therefore there's no point in placing redzones into __DATA,__cfstring.
      // Moreover, it causes the linker to crash on OS X 10.7
      if (Section.find("__DATA,__cfstring") == 0) {
        DEBUG(dbgs() << "Ignoring CFString: " << *G);
        continue;
      }
    }

    GlobalsToChange.push_back(G);
  }

  size_t n = GlobalsToChange.size();
  if (n == 0) return false;

  // A global is described by a structure
  //   size_t beg;
  //   size_t size;
  //   size_t size_with_redzone;
  //   const char *name;
  // We initialize an array of such structures and pass it to a run-time call.
  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
                                               IntptrTy, IntptrTy, NULL);
  SmallVector<Constant *, 16> Initializers(n);

  IRBuilder<> IRB(CtorInsertBefore);

  for (size_t i = 0; i < n; i++) {
    GlobalVariable *G = GlobalsToChange[i];
    PointerType *PtrTy = cast<PointerType>(G->getType());
    Type *Ty = PtrTy->getElementType();
    uint64_t SizeInBytes = TD->getTypeStoreSizeInBits(Ty) / 8;
    uint64_t RightRedzoneSize = RedzoneSize +
        (RedzoneSize - (SizeInBytes % RedzoneSize));
    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);

    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
    Constant *NewInitializer = ConstantStruct::get(
        NewTy, G->getInitializer(),
        Constant::getNullValue(RightRedZoneTy), NULL);

    SmallString<2048> DescriptionOfGlobal = G->getName();
    DescriptionOfGlobal += " (";
    DescriptionOfGlobal += M.getModuleIdentifier();
    DescriptionOfGlobal += ")";
    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);

    // Create a new global variable with enough space for a redzone.
//.........这里部分代码省略.........

bool StripDeadDebugInfo::runOnModule(Module &M) {
  bool Changed = false;

  // Debugging infomration is encoded in llvm IR using metadata. This is designed
  // such a way that debug info for symbols preserved even if symbols are
  // optimized away by the optimizer. This special pass removes debug info for 
  // such symbols.

  // llvm.dbg.gv keeps track of debug info for global variables.
  if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.gv")) {
    SmallVector<MDNode *, 8> MDs;
    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
      if (DIGlobalVariable(NMD->getOperand(i)).Verify())
        MDs.push_back(NMD->getOperand(i));
      else
        Changed = true;
    NMD->eraseFromParent();
    NMD = NULL;

    for (SmallVector<MDNode *, 8>::iterator I = MDs.begin(),
           E = MDs.end(); I != E; ++I) {
      GlobalVariable *GV = DIGlobalVariable(*I).getGlobal();
      if (GV && M.getGlobalVariable(GV->getName(), true)) {
        if (!NMD)
          NMD = M.getOrInsertNamedMetadata("llvm.dbg.gv");
        NMD->addOperand(*I);
      }
      else
        Changed = true;
    }
  }

  // llvm.dbg.sp keeps track of debug info for subprograms.
  if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.sp")) {
    SmallVector<MDNode *, 8> MDs;
    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
      if (DISubprogram(NMD->getOperand(i)).Verify())
        MDs.push_back(NMD->getOperand(i));
      else
        Changed = true;
    NMD->eraseFromParent();
    NMD = NULL;

    for (SmallVector<MDNode *, 8>::iterator I = MDs.begin(),
           E = MDs.end(); I != E; ++I) {
      bool FnIsLive = false;
      if (Function *F = DISubprogram(*I).getFunction())
        if (M.getFunction(F->getName()))
          FnIsLive = true;
      if (FnIsLive) {
          if (!NMD)
            NMD = M.getOrInsertNamedMetadata("llvm.dbg.sp");
          NMD->addOperand(*I);
      } else {
        // Remove llvm.dbg.lv.fnname named mdnode which may have been used
        // to hold debug info for dead function's local variables.
        StringRef FName = DISubprogram(*I).getLinkageName();
        if (FName.empty())
          FName = DISubprogram(*I).getName();
        if (NamedMDNode *LVNMD = 
            M.getNamedMetadata(Twine("llvm.dbg.lv.", 
                                     getRealLinkageName(FName)))) 
          LVNMD->eraseFromParent();
      }
    }
  }

  return Changed;
}

// destructively move the contents of src into dest
// this assumes that the targets of the two modules are the same
// including the DataLayout and ModuleFlags (for example)
// and that there is no module-level assembly
static void jl_merge_module(Module *dest, std::unique_ptr<Module> src)
{
    assert(dest != src.get());
    for (Module::global_iterator I = src->global_begin(), E = src->global_end(); I != E;) {
        GlobalVariable *sG = &*I;
        GlobalValue *dG = dest->getNamedValue(sG->getName());
        ++I;
        // Replace a declaration with the definition:
        if (dG) {
            if (sG->isDeclaration()) {
                sG->replaceAllUsesWith(dG);
                sG->eraseFromParent();
                continue;
            }
            else {
                dG->replaceAllUsesWith(sG);
                dG->eraseFromParent();
            }
        }
        // Reparent the global variable:
        sG->removeFromParent();
        dest->getGlobalList().push_back(sG);
        // Comdat is owned by the Module, recreate it in the new parent:
        addComdat(sG);
    }

    for (Module::iterator I = src->begin(), E = src->end(); I != E;) {
        Function *sG = &*I;
        GlobalValue *dG = dest->getNamedValue(sG->getName());
        ++I;
        // Replace a declaration with the definition:
        if (dG) {
            if (sG->isDeclaration()) {
                sG->replaceAllUsesWith(dG);
                sG->eraseFromParent();
                continue;
            }
            else {
                dG->replaceAllUsesWith(sG);
                dG->eraseFromParent();
            }
        }
        // Reparent the global variable:
        sG->removeFromParent();
        dest->getFunctionList().push_back(sG);
        // Comdat is owned by the Module, recreate it in the new parent:
        addComdat(sG);
    }

    for (Module::alias_iterator I = src->alias_begin(), E = src->alias_end(); I != E;) {
        GlobalAlias *sG = &*I;
        GlobalValue *dG = dest->getNamedValue(sG->getName());
        ++I;
        if (dG) {
            if (!dG->isDeclaration()) { // aliases are always definitions, so this test is reversed from the above two
                sG->replaceAllUsesWith(dG);
                sG->eraseFromParent();
                continue;
            }
            else {
                dG->replaceAllUsesWith(sG);
                dG->eraseFromParent();
            }
        }
        sG->removeFromParent();
        dest->getAliasList().push_back(sG);
    }

    // metadata nodes need to be explicitly merged not just copied
    // so there are special passes here for each known type of metadata
    NamedMDNode *sNMD = src->getNamedMetadata("llvm.dbg.cu");
    if (sNMD) {
        NamedMDNode *dNMD = dest->getOrInsertNamedMetadata("llvm.dbg.cu");
#if JL_LLVM_VERSION >= 30500
        for (NamedMDNode::op_iterator I = sNMD->op_begin(), E = sNMD->op_end(); I != E; ++I) {
            dNMD->addOperand(*I);
        }
#else
        for (unsigned i = 0, l = sNMD->getNumOperands(); i < l; i++) {
            dNMD->addOperand(sNMD->getOperand(i));
        }
#endif
    }
}

bool GlobalMerge::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
                          const BitVector &GlobalSet, Module &M, bool isConst,
                          unsigned AddrSpace) const {
  assert(Globals.size() > 1);

  Type *Int32Ty = Type::getInt32Ty(M.getContext());
  auto &DL = M.getDataLayout();

  DEBUG(dbgs() << " Trying to merge set, starts with #"
               << GlobalSet.find_first() << "\n");

  ssize_t i = GlobalSet.find_first();
  while (i != -1) {
    ssize_t j = 0;
    uint64_t MergedSize = 0;
    std::vector<Type*> Tys;
    std::vector<Constant*> Inits;

    bool HasExternal = false;
    GlobalVariable *TheFirstExternal = nullptr;
    for (j = i; j != -1; j = GlobalSet.find_next(j)) {
      Type *Ty = Globals[j]->getValueType();
      MergedSize += DL.getTypeAllocSize(Ty);
      if (MergedSize > MaxOffset) {
        break;
      }
      Tys.push_back(Ty);
      Inits.push_back(Globals[j]->getInitializer());

      if (Globals[j]->hasExternalLinkage() && !HasExternal) {
        HasExternal = true;
        TheFirstExternal = Globals[j];
      }
    }

    // If merged variables doesn't have external linkage, we needn't to expose
    // the symbol after merging.
    GlobalValue::LinkageTypes Linkage = HasExternal
                                            ? GlobalValue::ExternalLinkage
                                            : GlobalValue::InternalLinkage;
    StructType *MergedTy = StructType::get(M.getContext(), Tys);
    Constant *MergedInit = ConstantStruct::get(MergedTy, Inits);

    // On Darwin external linkage needs to be preserved, otherwise dsymutil
    // cannot preserve the debug info for the merged variables.  If they have
    // external linkage, use the symbol name of the first variable merged as the
    // suffix of global symbol name.  This avoids a link-time naming conflict
    // for the _MergedGlobals symbols.
    Twine MergedName =
        (IsMachO && HasExternal)
            ? "_MergedGlobals_" + TheFirstExternal->getName()
            : "_MergedGlobals";
    auto MergedLinkage = IsMachO ? Linkage : GlobalValue::PrivateLinkage;
    auto *MergedGV = new GlobalVariable(
        M, MergedTy, isConst, MergedLinkage, MergedInit, MergedName, nullptr,
        GlobalVariable::NotThreadLocal, AddrSpace);

    const StructLayout *MergedLayout = DL.getStructLayout(MergedTy);

    for (ssize_t k = i, idx = 0; k != j; k = GlobalSet.find_next(k), ++idx) {
      GlobalValue::LinkageTypes Linkage = Globals[k]->getLinkage();
      std::string Name = Globals[k]->getName();

      // Copy metadata while adjusting any debug info metadata by the original
      // global's offset within the merged global.
      MergedGV->copyMetadata(Globals[k], MergedLayout->getElementOffset(idx));

      Constant *Idx[2] = {
        ConstantInt::get(Int32Ty, 0),
        ConstantInt::get(Int32Ty, idx),
      };
      Constant *GEP =
          ConstantExpr::getInBoundsGetElementPtr(MergedTy, MergedGV, Idx);
      Globals[k]->replaceAllUsesWith(GEP);
      Globals[k]->eraseFromParent();

      // When the linkage is not internal we must emit an alias for the original
      // variable name as it may be accessed from another object. On non-Mach-O
      // we can also emit an alias for internal linkage as it's safe to do so.
      // It's not safe on Mach-O as the alias (and thus the portion of the
      // MergedGlobals variable) may be dead stripped at link time.
      if (Linkage != GlobalValue::InternalLinkage || !IsMachO) {
        GlobalAlias::create(Tys[idx], AddrSpace, Linkage, Name, GEP, &M);
      }

      NumMerged++;
    }
    i = j;
  }

  return true;
}

bool ReflectorPass::runOnModule(Module & module) {
  using llvm::Module;

  Module::GlobalListType & globals = module.getGlobalList();
  for (Module::GlobalListType::iterator it = globals.begin(); it != globals.end(); ++it) {
    if (GlobalVariable * globalVar = dyn_cast<GlobalVariable>(it)) {
      if (globalVar->getName().startswith(".module")) {
//        errs() << globalVar->getName() << "\n";
        modules_[globalVar->getName()] = globalVar;
      } else if (globalVar->getName().startswith(".package")) {
//        errs() << globalVar->getName() << "\n";
        std::string packageName(globalVar->getName());
        packageName.erase(0, 9); // remove ".package."
        /*Package * p =*/ getOrCreatePackage(packageName, globalVar);
      }
    }
  }

  if (!packages_.empty()) {
    Type * packageType = requireType("tart.reflect.Package", module);
    Type * moduleArrayType = requireType("tart.reflect.Module[]", module);
    Type * packageArrayType = requireType("tart.reflect.Package[]", module);
    Type * stringType = requireType("tart.core.String", module);
    Type * moduleType = requireType("tart.reflect.Module", module);

    Constant * emptyModuleArray = requireGlobal("tart.reflect.Module[].emptyArray", module);
    Constant * emptyPackageArray = requireGlobal("tart.reflect.Package[].emptyArray", module);
    Constant * packageTypeInfo = requireGlobal("tart.reflect.Package.TIB", module);
    Constant * packageArrayTypeInfo = requireGlobal("tart.reflect.Package[].TIB", module);
    Constant * moduleArrayTypeInfo = requireGlobal("tart.reflect.Module[].TIB", module);
    Constant * stringTypeInfo = requireGlobal("tart.core.String.TIB", module);

    for (GlobalVarMap::iterator it = modules_.begin(); it != modules_.end(); ++it) {
      GlobalVariable * moduleVar = it->second;
      std::string packageName(moduleVar->getName());
      // remove everything after the last '.'
      packageName.erase(packageName.rfind('.'), packageName.npos);
      packageName.erase(0, 8); // remove ".module."

      Package * p = getOrCreateSubPackage(packageName, &module);
      if (p != NULL) {
        //errs() << "Package " << packageName << " found for module " << moduleVar->getName() << "\n";
        p->addModule(moduleVar);
      }
    }

    for (PackageMap::iterator it = packages_.begin(); it != packages_.end(); ++it) {
      Package * p = it->second;

      // Start construction of the updated package structure.

      ConstantBuilder cb(module);
      cb.addObjectHeader(packageTypeInfo);    // Object header

      if (p->global()->hasInitializer()) {
        ConstantRef packageConst = p->global()->getInitializer();
        cb.addField(packageConst.operand(1));   // Package name
      } else {
        cb.addField(createString(module, stringTypeInfo, stringType, p->name()));
      }

      // List of modules in package

      if (!p->modules().empty()) {
        Type * modulePtrType = moduleType->getPointerTo();
        ConstantList modules;
        std::sort(p->modules().begin(), p->modules().end(), ModuleNameComparator());
        for (GlobalVarList::iterator m = p->modules().begin(); m != p->modules().end(); ++m) {
          modules.push_back(ConstantExpr::getPointerCast(*m, modulePtrType));
        }

        cb.addField(createArray(module, modules, moduleArrayTypeInfo, moduleArrayType,
            ".modules." + p->name()));
      } else {
        cb.addField(emptyModuleArray);
      }

      // List of subpackages in package

      if (!p->subpackages().empty()) {
        ConstantList subpackages;
        std::sort(p->subpackages().begin(), p->subpackages().end(), PackageNameComparator());
        for (PackageList::iterator m = p->subpackages().begin(); m != p->subpackages().end(); ++m) {
          Package * subPackage = *m;
          assert(subPackage->global() != NULL);
          subpackages.push_back(subPackage->global());
        }

        cb.addField(createArray(module, subpackages, packageArrayTypeInfo, packageArrayType,
            ".subpackages." + p->name()));
      } else {
        cb.addField(emptyPackageArray);
      }

      p->global()->setInitializer(cb.buildStruct(packageType));
    }
  }

  return false;
}

/// emit_global_to_llvm - Emit the specified VAR_DECL or aggregate CONST_DECL to
/// LLVM as a global variable.  This function implements the end of
/// assemble_variable.
void emit_global_to_llvm(tree decl) {
  if (errorcount || sorrycount) return;

  // FIXME: Support alignment on globals: DECL_ALIGN.
  // FIXME: DECL_PRESERVE_P indicates the var is marked with attribute 'used'.

  // Global register variables don't turn into LLVM GlobalVariables.
  if (TREE_CODE(decl) == VAR_DECL && DECL_REGISTER(decl))
    return;

  timevar_push(TV_LLVM_GLOBALS);

  // Get or create the global variable now.
  GlobalVariable *GV = cast<GlobalVariable>(DECL_LLVM(decl));
  
  // Convert the initializer over.
  Constant *Init;
  if (DECL_INITIAL(decl) == 0 || DECL_INITIAL(decl) == error_mark_node) {
    // This global should be zero initialized.  Reconvert the type in case the
    // forward def of the global and the real def differ in type (e.g. declared
    // as 'int A[]', and defined as 'int A[100]').
    Init = Constant::getNullValue(ConvertType(TREE_TYPE(decl)));
  } else {
    assert((TREE_CONSTANT(DECL_INITIAL(decl)) || 
            TREE_CODE(DECL_INITIAL(decl)) == STRING_CST) &&
           "Global initializer should be constant!");
    
    // Temporarily set an initializer for the global, so we don't infinitely
    // recurse.  If we don't do this, we can hit cases where we see "oh a global
    // with an initializer hasn't been initialized yet, call emit_global_to_llvm
    // on it".  When constructing the initializer it might refer to itself.
    // this can happen for things like void *G = &G;
    //
    GV->setInitializer(UndefValue::get(GV->getType()->getElementType()));
    Init = TreeConstantToLLVM::Convert(DECL_INITIAL(decl));
  }

  // If we had a forward definition that has a type that disagrees with our
  // initializer, insert a cast now.  This sort of thing occurs when we have a
  // global union, and the LLVM type followed a union initializer that is
  // different from the union element used for the type.
  if (GV->getType()->getElementType() != Init->getType()) {
    GV->removeFromParent();
    GlobalVariable *NGV = new GlobalVariable(Init->getType(), GV->isConstant(),
                                             GlobalValue::ExternalLinkage, 0,
                                             GV->getName(), TheModule);
    GV->replaceAllUsesWith(ConstantExpr::getBitCast(NGV, GV->getType()));
    delete GV;
    SET_DECL_LLVM(decl, NGV);
    GV = NGV;
  }
 
  // Set the initializer.
  GV->setInitializer(Init);

  // Set thread local (TLS)
  if (TREE_CODE(decl) == VAR_DECL && DECL_THREAD_LOCAL(decl))
    GV->setThreadLocal(true);

  // Set the linkage.
  if (!TREE_PUBLIC(decl)) {
    GV->setLinkage(GlobalValue::InternalLinkage);
  } else if (DECL_WEAK(decl) || DECL_ONE_ONLY(decl) ||
             (DECL_COMMON(decl) &&  // DECL_COMMON is only meaningful if no init
              (!DECL_INITIAL(decl) || DECL_INITIAL(decl) == error_mark_node))) {
    // llvm-gcc also includes DECL_VIRTUAL_P here.
    GV->setLinkage(GlobalValue::WeakLinkage);
  } else if (DECL_COMDAT(decl)) {
    GV->setLinkage(GlobalValue::LinkOnceLinkage);
  }

#ifdef TARGET_ADJUST_LLVM_LINKAGE
  TARGET_ADJUST_LLVM_LINKAGE(GV,decl);
#endif /* TARGET_ADJUST_LLVM_LINKAGE */

  // Handle visibility style
  if (TREE_PUBLIC(decl)) {
    if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN)
      GV->setVisibility(GlobalValue::HiddenVisibility);
    else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED)
      GV->setVisibility(GlobalValue::ProtectedVisibility);
  }

  // Set the section for the global.
  if (TREE_CODE(decl) == VAR_DECL || TREE_CODE(decl) == CONST_DECL) {
    if (DECL_SECTION_NAME(decl)) {
      GV->setSection(TREE_STRING_POINTER(DECL_SECTION_NAME(decl)));
#ifdef LLVM_IMPLICIT_TARGET_GLOBAL_VAR_SECTION
    } else if (const char *Section = 
                LLVM_IMPLICIT_TARGET_GLOBAL_VAR_SECTION(decl)) {
      GV->setSection(Section);
#endif
    }
    
    // Set the alignment for the global if one of the following condition is met
    // 1) DECL_ALIGN_UNIT does not match alignment as per ABI specification
    // 2) DECL_ALIGN is set by user.
//.........这里部分代码省略.........

//.........这里部分代码省略.........
    DECL_COMMON(decl) = 0;
  
  // Okay, now we need to create an LLVM global variable or function for this
  // object.  Note that this is quite possibly a forward reference to the
  // object, so its type may change later.
  if (TREE_CODE(decl) == FUNCTION_DECL) {
    assert(Name[0] && "Function with empty name!");
    // If this function has already been created, reuse the decl.  This happens
    // when we have something like __builtin_memset and memset in the same file.
    Function *FnEntry = TheModule->getFunction(Name);
    if (FnEntry == 0) {
      unsigned CC;
      const FunctionType *Ty = 
        TheTypeConverter->ConvertFunctionType(TREE_TYPE(decl), decl, NULL, CC);
      FnEntry = new Function(Ty, Function::ExternalLinkage, Name, TheModule);
      FnEntry->setCallingConv(CC);

      // Check for external weak linkage
      if (DECL_EXTERNAL(decl) && DECL_WEAK(decl))
        FnEntry->setLinkage(Function::ExternalWeakLinkage);
      
#ifdef TARGET_ADJUST_LLVM_LINKAGE
      TARGET_ADJUST_LLVM_LINKAGE(FnEntry,decl);
#endif /* TARGET_ADJUST_LLVM_LINKAGE */

      // Handle visibility style
      if (TREE_PUBLIC(decl)) {
        if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN)
          FnEntry->setVisibility(GlobalValue::HiddenVisibility);
        else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED)
          FnEntry->setVisibility(GlobalValue::ProtectedVisibility);
      }

      assert(FnEntry->getName() == Name &&"Preexisting fn with the same name!");
    }
    SET_DECL_LLVM(decl, FnEntry);
  } else {
    assert((TREE_CODE(decl) == VAR_DECL ||
            TREE_CODE(decl) == CONST_DECL) && "Not a function or var decl?");
    const Type *Ty = ConvertType(TREE_TYPE(decl));
    GlobalVariable *GV ;

    // If we have "extern void foo", make the global have type {} instead of
    // type void.
    if (Ty == Type::VoidTy) 
      Ty = StructType::get(std::vector<const Type*>(), false);
    
    if (Name[0] == 0) {   // Global has no name.
      GV = new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage, 0,
                              "", TheModule);

      // Check for external weak linkage
      if (DECL_EXTERNAL(decl) && DECL_WEAK(decl))
        GV->setLinkage(GlobalValue::ExternalWeakLinkage);
      
#ifdef TARGET_ADJUST_LLVM_LINKAGE
      TARGET_ADJUST_LLVM_LINKAGE(GV,decl);
#endif /* TARGET_ADJUST_LLVM_LINKAGE */

      // Handle visibility style
      if (TREE_PUBLIC(decl)) {
        if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN)
          GV->setVisibility(GlobalValue::HiddenVisibility);
        else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED)
          GV->setVisibility(GlobalValue::ProtectedVisibility);
      }

bool BlackList::isIn(const GlobalVariable &G) const {
  return isIn(*G.getParent()) || inSection("global", G.getName());
}

bool BlackList::isInInit(const GlobalVariable &G) const {
  return (isIn(*G.getParent()) ||
          inSection("global-init", G.getName()) ||
          inSection("global-init-type", GetGVTypeString(G)));
}

bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
                          Module &M, bool isConst, unsigned AddrSpace) const {
  const TargetLowering *TLI = TM->getTargetLowering();
  const DataLayout *DL = TLI->getDataLayout();

  // FIXME: Infer the maximum possible offset depending on the actual users
  // (these max offsets are different for the users inside Thumb or ARM
  // functions)
  unsigned MaxOffset = TLI->getMaximalGlobalOffset();

  // FIXME: Find better heuristics
  std::stable_sort(Globals.begin(), Globals.end(),
                   [DL](const GlobalVariable *GV1, const GlobalVariable *GV2) {
    Type *Ty1 = cast<PointerType>(GV1->getType())->getElementType();
    Type *Ty2 = cast<PointerType>(GV2->getType())->getElementType();

    return (DL->getTypeAllocSize(Ty1) < DL->getTypeAllocSize(Ty2));
  });

  Type *Int32Ty = Type::getInt32Ty(M.getContext());

  assert(Globals.size() > 1);

  // FIXME: This simple solution merges globals all together as maximum as
  // possible. However, with this solution it would be hard to remove dead
  // global symbols at link-time. An alternative solution could be checking
  // global symbols references function by function, and make the symbols
  // being referred in the same function merged and we would probably need
  // to introduce heuristic algorithm to solve the merge conflict from
  // different functions.
  for (size_t i = 0, e = Globals.size(); i != e; ) {
    size_t j = 0;
    uint64_t MergedSize = 0;
    std::vector<Type*> Tys;
    std::vector<Constant*> Inits;

    bool HasExternal = false;
    GlobalVariable *TheFirstExternal = 0;
    for (j = i; j != e; ++j) {
      Type *Ty = Globals[j]->getType()->getElementType();
      MergedSize += DL->getTypeAllocSize(Ty);
      if (MergedSize > MaxOffset) {
        break;
      }
      Tys.push_back(Ty);
      Inits.push_back(Globals[j]->getInitializer());

      if (Globals[j]->hasExternalLinkage() && !HasExternal) {
        HasExternal = true;
        TheFirstExternal = Globals[j];
      }
    }

    // If merged variables doesn't have external linkage, we needn't to expose
    // the symbol after merging.
    GlobalValue::LinkageTypes Linkage = HasExternal
                                            ? GlobalValue::ExternalLinkage
                                            : GlobalValue::InternalLinkage;

    // If merged variables have external linkage, we use symbol name of the
    // first variable merged as the suffix of global symbol name. This would
    // be able to avoid the link-time naming conflict for globalm symbols.
    Twine MergedGVName = HasExternal
                             ? "_MergedGlobals_" + TheFirstExternal->getName()
                             : "_MergedGlobals";

    StructType *MergedTy = StructType::get(M.getContext(), Tys);
    Constant *MergedInit = ConstantStruct::get(MergedTy, Inits);

    GlobalVariable *MergedGV = new GlobalVariable(
        M, MergedTy, isConst, Linkage, MergedInit, MergedGVName, nullptr,
        GlobalVariable::NotThreadLocal, AddrSpace);

    for (size_t k = i; k < j; ++k) {
      GlobalValue::LinkageTypes Linkage = Globals[k]->getLinkage();
      std::string Name = Globals[k]->getName();

      Constant *Idx[2] = {
        ConstantInt::get(Int32Ty, 0),
        ConstantInt::get(Int32Ty, k-i)
      };
      Constant *GEP = ConstantExpr::getInBoundsGetElementPtr(MergedGV, Idx);
      Globals[k]->replaceAllUsesWith(GEP);
      Globals[k]->eraseFromParent();

      if (Linkage != GlobalValue::InternalLinkage) {
        // Generate a new alias...
        auto *PTy = cast<PointerType>(GEP->getType());
        GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
                            Linkage, Name, GEP, &M);
      }

      NumMerged++;
    }
    i = j;
  }

  return true;
}

// This function replaces all global variables with new variables that have
// trailing redzones. It also creates a function that poisons
// redzones and inserts this function into llvm.global_ctors.
bool AddressSanitizer::insertGlobalRedzones(Module &M) {
  SmallVector<GlobalVariable *, 16> GlobalsToChange;

  for (Module::GlobalListType::iterator G = M.global_begin(),
       E = M.global_end(); G != E; ++G) {
    if (ShouldInstrumentGlobal(G))
      GlobalsToChange.push_back(G);
  }

  size_t n = GlobalsToChange.size();
  if (n == 0) return false;

  // A global is described by a structure
  //   size_t beg;
  //   size_t size;
  //   size_t size_with_redzone;
  //   const char *name;
  //   size_t has_dynamic_init;
  // We initialize an array of such structures and pass it to a run-time call.
  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
                                               IntptrTy, IntptrTy,
                                               IntptrTy, NULL);
  SmallVector<Constant *, 16> Initializers(n), DynamicInit;

  IRBuilder<> IRB(CtorInsertBefore);

  if (ClInitializers)
    FindDynamicInitializers(M);

  // The addresses of the first and last dynamically initialized globals in
  // this TU.  Used in initialization order checking.
  Value *FirstDynamic = 0, *LastDynamic = 0;

  for (size_t i = 0; i < n; i++) {
    GlobalVariable *G = GlobalsToChange[i];
    PointerType *PtrTy = cast<PointerType>(G->getType());
    Type *Ty = PtrTy->getElementType();
    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
    uint64_t RightRedzoneSize = RedzoneSize +
        (RedzoneSize - (SizeInBytes % RedzoneSize));
    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
    // Determine whether this global should be poisoned in initialization.
    bool GlobalHasDynamicInitializer = HasDynamicInitializer(G);
    // Don't check initialization order if this global is blacklisted.
    GlobalHasDynamicInitializer &= !BL->isInInit(*G);

    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
    Constant *NewInitializer = ConstantStruct::get(
        NewTy, G->getInitializer(),
        Constant::getNullValue(RightRedZoneTy), NULL);

    SmallString<2048> DescriptionOfGlobal = G->getName();
    DescriptionOfGlobal += " (";
    DescriptionOfGlobal += M.getModuleIdentifier();
    DescriptionOfGlobal += ")";
    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);

    // Create a new global variable with enough space for a redzone.
    GlobalVariable *NewGlobal = new GlobalVariable(
        M, NewTy, G->isConstant(), G->getLinkage(),
        NewInitializer, "", G, G->getThreadLocalMode());
    NewGlobal->copyAttributesFrom(G);
    NewGlobal->setAlignment(RedzoneSize);

    Value *Indices2[2];
    Indices2[0] = IRB.getInt32(0);
    Indices2[1] = IRB.getInt32(0);

    G->replaceAllUsesWith(
        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
    NewGlobal->takeName(G);
    G->eraseFromParent();

    Initializers[i] = ConstantStruct::get(
        GlobalStructTy,
        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
        ConstantInt::get(IntptrTy, SizeInBytes),
        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
        ConstantExpr::getPointerCast(Name, IntptrTy),
        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
        NULL);

    // Populate the first and last globals declared in this TU.
    if (ClInitializers && GlobalHasDynamicInitializer) {
      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
      if (FirstDynamic == 0)
        FirstDynamic = LastDynamic;
    }

    DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
  }

  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
  GlobalVariable *AllGlobals = new GlobalVariable(
      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");

//.........这里部分代码省略.........

std::vector<SDBuildCHA::nmd_t>
SDBuildCHA::extractMetadata(NamedMDNode* md) {
  std::set<vtbl_name_t> classes;
  std::vector<SDBuildCHA::nmd_t> infoVec;

  unsigned op = 0;

  do {
    SDBuildCHA::nmd_t info;
    MDString* infoMDstr = dyn_cast_or_null<MDString>(md->getOperand(op++)->getOperand(0));
    assert(infoMDstr);
    info.className = infoMDstr->getString().str();
    GlobalVariable* classVtbl = sd_mdnodeToGV(md->getOperand(op++));

    if (classVtbl) {
      info.className = classVtbl->getName();
    }

    unsigned numOperands = sd_getNumberFromMDTuple(md->getOperand(op++)->getOperand(0));

    for (unsigned i = op; i < op + numOperands; ++i) {
      SDBuildCHA::nmd_sub_t subInfo;
      llvm::MDTuple* tup = dyn_cast<llvm::MDTuple>(md->getOperand(i));
      assert(tup);
      assert(tup->getNumOperands() == 5);

      subInfo.order = sd_getNumberFromMDTuple(tup->getOperand(0));
      subInfo.start = sd_getNumberFromMDTuple(tup->getOperand(1));
      subInfo.end = sd_getNumberFromMDTuple(tup->getOperand(2));
      subInfo.addressPoint = sd_getNumberFromMDTuple(tup->getOperand(3));
      llvm::MDTuple* parentsTup = dyn_cast<llvm::MDTuple>(tup->getOperand(4));

      unsigned numParents = sd_getNumberFromMDTuple(parentsTup->getOperand(0));
      for (int j = 0; j < numParents; j++) {
        vtbl_name_t ptName = sd_getStringFromMDTuple(parentsTup->getOperand(1+j*3));
        unsigned ptIdx = sd_getNumberFromMDTuple(parentsTup->getOperand(1+j*3+1));
        GlobalVariable* parentVtable = sd_mdnodeToGV(parentsTup->getOperand(1+j*3+2).get());

        if (parentVtable) {
          ptName = parentVtable->getName();
        }
        subInfo.parents.insert(vtbl_t(ptName, ptIdx));
      }

      bool currRangeCheck = (subInfo.start <= subInfo.addressPoint &&
                     subInfo.addressPoint <= subInfo.end);
      bool prevVtblCheck = (i == op || (--info.subVTables.end())->end < subInfo.start);

      assert(currRangeCheck && prevVtblCheck);

      info.subVTables.push_back(subInfo);
    }
    op += numOperands;

    if (classes.count(info.className) == 0) {
      classes.insert(info.className);
      infoVec.push_back(info);
    }
  } while (op < md->getNumOperands());

  return infoVec;
}