C++ SmallVector::pop_back方法代码示例

AbstractFunctionDecl *SILDeclRef::getOverriddenWitnessTableEntry(
                                                 AbstractFunctionDecl *func) {
  if (!isa<ProtocolDecl>(func->getDeclContext()))
    return func;

  AbstractFunctionDecl *bestOverridden = nullptr;

  SmallVector<AbstractFunctionDecl *, 4> stack;
  SmallPtrSet<AbstractFunctionDecl *, 4> visited;
  stack.push_back(func);
  visited.insert(func);

  while (!stack.empty()) {
    auto current = stack.back();
    stack.pop_back();

    auto overriddenDecls = current->getOverriddenDecls();
    if (overriddenDecls.empty()) {
      // This entry introduced a witness table entry. Determine whether it is
      // better than the best entry we've seen thus far.
      if (!bestOverridden ||
          ProtocolDecl::compare(
                        cast<ProtocolDecl>(current->getDeclContext()),
                        cast<ProtocolDecl>(bestOverridden->getDeclContext()))
            < 0) {
        bestOverridden = cast<AbstractFunctionDecl>(current);
      }

      continue;
    }

    // Add overridden declarations to the stack.
    for (auto overridden : overriddenDecls) {
      auto overriddenFunc = cast<AbstractFunctionDecl>(overridden);
      if (visited.insert(overriddenFunc).second)
        stack.push_back(overriddenFunc);
    }
  }

  return bestOverridden;
}

bool CXXRecordDecl::forallBases(ForallBasesCallback *BaseMatches,
                                void *OpaqueData,
                                bool AllowShortCircuit) const {
  SmallVector<const CXXRecordDecl*, 8> Queue;

  const CXXRecordDecl *Record = this;
  bool AllMatches = true;
  while (true) {
    for (CXXRecordDecl::base_class_const_iterator
           I = Record->bases_begin(), E = Record->bases_end(); I != E; ++I) {
      const RecordType *Ty = I->getType()->getAs<RecordType>();
      if (!Ty) {
        if (AllowShortCircuit) return false;
        AllMatches = false;
        continue;
      }

      CXXRecordDecl *Base = 
            cast_or_null<CXXRecordDecl>(Ty->getDecl()->getDefinition());
      if (!Base) {
        if (AllowShortCircuit) return false;
        AllMatches = false;
        continue;
      }
      
      Queue.push_back(Base);
      if (!BaseMatches(Base, OpaqueData)) {
        if (AllowShortCircuit) return false;
        AllMatches = false;
        continue;
      }
    }

    if (Queue.empty()) break;
    Record = Queue.back(); // not actually a queue.
    Queue.pop_back();
  }

  return AllMatches;
}

void NestedNameSpecifierLocBuilder::MakeTrivial(ASTContext &Context, 
                                                NestedNameSpecifier *Qualifier, 
                                                SourceRange R) {
  Representation = Qualifier;
  
  // Construct bogus (but well-formed) source information for the 
  // nested-name-specifier.
  BufferSize = 0;
  SmallVector<NestedNameSpecifier *, 4> Stack;
  for (NestedNameSpecifier *NNS = Qualifier; NNS; NNS = NNS->getPrefix())
    Stack.push_back(NNS);
  while (!Stack.empty()) {
    NestedNameSpecifier *NNS = Stack.back();
    Stack.pop_back();
    switch (NNS->getKind()) {
      case NestedNameSpecifier::Identifier:
      case NestedNameSpecifier::Namespace:
      case NestedNameSpecifier::NamespaceAlias:
        SaveSourceLocation(R.getBegin(), Buffer, BufferSize, BufferCapacity);
        break;
        
      case NestedNameSpecifier::TypeSpec:
      case NestedNameSpecifier::TypeSpecWithTemplate: {
        TypeSourceInfo *TSInfo
        = Context.getTrivialTypeSourceInfo(QualType(NNS->getAsType(), 0),
                                           R.getBegin());
        SavePointer(TSInfo->getTypeLoc().getOpaqueData(), Buffer, BufferSize, 
                    BufferCapacity);
        break;
      }
        
      case NestedNameSpecifier::Global:
        break;
    }
    
    // Save the location of the '::'.
    SaveSourceLocation(Stack.empty()? R.getEnd() : R.getBegin(), 
                       Buffer, BufferSize, BufferCapacity);
  }
}

/// constructScopeNest
void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
  assert(Scope && "Unable to calculate scope dominance graph!");
  SmallVector<LexicalScope *, 4> WorkStack;
  WorkStack.push_back(Scope);
  unsigned Counter = 0;
  while (!WorkStack.empty()) {
    LexicalScope *WS = WorkStack.back();
    const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
    bool visitedChildren = false;
    for (auto &ChildScope : Children)
      if (!ChildScope->getDFSOut()) {
        WorkStack.push_back(ChildScope);
        visitedChildren = true;
        ChildScope->setDFSIn(++Counter);
        break;
      }
    if (!visitedChildren) {
      WorkStack.pop_back();
      WS->setDFSOut(++Counter);
    }
  }
}

// Look through full copies and PHIs to get the set of non-copy MachineInstrs
// that can produce MI.
void A15SDOptimizer::elideCopiesAndPHIs(MachineInstr *MI,
                                        SmallVectorImpl<MachineInstr*> &Outs) {
   // Looking through PHIs may create loops so we need to track what
   // instructions we have visited before.
   std::set<MachineInstr *> Reached;
   SmallVector<MachineInstr *, 8> Front;
   Front.push_back(MI);
   while (Front.size() != 0) {
     MI = Front.back();
     Front.pop_back();

     // If we have already explored this MachineInstr, ignore it.
     if (Reached.find(MI) != Reached.end())
       continue;
     Reached.insert(MI);
     if (MI->isPHI()) {
       for (unsigned I = 1, E = MI->getNumOperands(); I != E; I += 2) {
         unsigned Reg = MI->getOperand(I).getReg();
         if (!TRI->isVirtualRegister(Reg)) {
           continue;
         }
         MachineInstr *NewMI = MRI->getVRegDef(Reg);
         if (!NewMI)
           continue;
         Front.push_back(NewMI);
       }
     } else if (MI->isFullCopy()) {
       if (!TRI->isVirtualRegister(MI->getOperand(1).getReg()))
         continue;
       MachineInstr *NewMI = MRI->getVRegDef(MI->getOperand(1).getReg());
       if (!NewMI)
         continue;
       Front.push_back(NewMI);
     } else {
       DEBUG(dbgs() << "Found partial copy" << *MI <<"\n");
       Outs.push_back(MI);
     }
   }
}

void ScheduleDAGSDNodes::dumpNode(const SUnit &SU) const {
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  dumpNodeName(SU);
  dbgs() << ": ";

  if (!SU.getNode()) {
    dbgs() << "PHYS REG COPY\n";
    return;
  }

  SU.getNode()->dump(DAG);
  dbgs() << "\n";
  SmallVector<SDNode *, 4> GluedNodes;
  for (SDNode *N = SU.getNode()->getGluedNode(); N; N = N->getGluedNode())
    GluedNodes.push_back(N);
  while (!GluedNodes.empty()) {
    dbgs() << "    ";
    GluedNodes.back()->dump(DAG);
    dbgs() << "\n";
    GluedNodes.pop_back();
  }
#endif
}

void Module::markUnavailable(bool MissingRequirement) {
  if (!IsAvailable)
    return;

  SmallVector<Module *, 2> Stack;
  Stack.push_back(this);
  while (!Stack.empty()) {
    Module *Current = Stack.back();
    Stack.pop_back();

    if (!Current->IsAvailable)
      continue;

    Current->IsAvailable = false;
    Current->IsMissingRequirement |= MissingRequirement;
    for (submodule_iterator Sub = Current->submodule_begin(),
                         SubEnd = Current->submodule_end();
         Sub != SubEnd; ++Sub) {
      if ((*Sub)->IsAvailable)
        Stack.push_back(*Sub);
    }
  }
}

static bool IsValueIntLoadRecursive(Value *V) {
  SmallVector<Value*, 4> Worklist;
  DenseSet<const Value *> VisitedValues;
  Worklist.push_back(V);
  VisitedValues.insert(V);

  while (!Worklist.empty()) {
    Value *CurValue = Worklist.back();
    Worklist.pop_back();

    if (!CanCheckValue(CurValue))
      continue;

    if (IsLoad(CurValue))
      return true;

    if (User *U = dyn_cast<User>(CurValue)) {
      // Do not walk through call instructions. The call arguments are not
      // necessarily directly related to the result, so it makes no sense to
      // cross-check them.
      //
      // Alternatively we could check call return values as if they were loads
      // expected to be datarando'd, but this may add false positives. Will
      // just ignore calls for now.
      if (isa<CallInst>(CurValue) ||
          isa<InvokeInst>(CurValue)) {
        continue;
      }

      for (Value *V : U->operands())
        if (VisitedValues.insert(V).second)
          Worklist.push_back(V);
    }
  }

  return false;
}

      bool Find(const TypedValueRegion *R) {
        QualType T = R->getValueType();
        if (const RecordType *RT = T->getAsStructureType()) {
          const RecordDecl *RD = RT->getDecl()->getDefinition();
          assert(RD && "Referred record has no definition");
          for (const auto *I : RD->fields()) {
            const FieldRegion *FR = MrMgr.getFieldRegion(I, R);
            FieldChain.push_back(I);
            T = I->getType();
            if (T->getAsStructureType()) {
              if (Find(FR))
                return true;
            }
            else {
              const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR));
              if (V.isUndef())
                return true;
            }
            FieldChain.pop_back();
          }
        }

        return false;
      }

/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
/// trivially dead instruction, delete it.  If that makes any of its operands
/// trivially dead, delete them too, recursively.
///
/// If DeadInst is specified, the vector is filled with the instructions that
/// are actually deleted.
void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V,
                                      SmallVectorImpl<Instruction*> *DeadInst) {
  Instruction *I = dyn_cast<Instruction>(V);
  if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
    return;
  
  SmallVector<Instruction*, 16> DeadInsts;
  DeadInsts.push_back(I);
  
  while (!DeadInsts.empty()) {
    I = DeadInsts.back();
    DeadInsts.pop_back();

    // If the client wanted to know, tell it about deleted instructions.
    if (DeadInst)
      DeadInst->push_back(I);
    
    // Null out all of the instruction's operands to see if any operand becomes
    // dead as we go.
    for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
      Value *OpV = I->getOperand(i);
      I->setOperand(i, 0);
      
      if (!OpV->use_empty()) continue;
    
      // If the operand is an instruction that became dead as we nulled out the
      // operand, and if it is 'trivially' dead, delete it in a future loop
      // iteration.
      if (Instruction *OpI = dyn_cast<Instruction>(OpV))
        if (isInstructionTriviallyDead(OpI))
          DeadInsts.push_back(OpI);
    }
    
    I->eraseFromParent();
  }
}

//.........这里部分代码省略.........
        if (!Callee || Callee->isDeclaration()) continue;
      
        // If this call site was obtained by inlining another function, verify
        // that the include path for the function did not include the callee
        // itself.  If so, we'd be recursively inlining the same function,
        // which would provide the same callsites, which would cause us to
        // infinitely inline.
        int InlineHistoryID = CallSites[CSi].second;
        if (InlineHistoryID != -1 &&
            InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory))
          continue;
        
        LLVMContext &CallerCtx = Caller->getContext();

        // Get DebugLoc to report. CS will be invalid after Inliner.
        DebugLoc DLoc = CS.getInstruction()->getDebugLoc();

        // If the policy determines that we should inline this function,
        // try to do so.
        if (!shouldInline(CS)) {
          emitOptimizationRemarkMissed(CallerCtx, DEBUG_TYPE, *Caller, DLoc,
                                       Twine(Callee->getName() +
                                             " will not be inlined into " +
                                             Caller->getName()));
          continue;
        }

        // Attempt to inline the function.
        if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas,
                                  InlineHistoryID, InsertLifetime)) {
          emitOptimizationRemarkMissed(CallerCtx, DEBUG_TYPE, *Caller, DLoc,
                                       Twine(Callee->getName() +
                                             " will not be inlined into " +
                                             Caller->getName()));
          continue;
        }
        ++NumInlined;

        // Report the inline decision.
        emitOptimizationRemark(
            CallerCtx, DEBUG_TYPE, *Caller, DLoc,
            Twine(Callee->getName() + " inlined into " + Caller->getName()));

        // If inlining this function gave us any new call sites, throw them
        // onto our worklist to process.  They are useful inline candidates.
        if (!InlineInfo.InlinedCalls.empty()) {
          // Create a new inline history entry for this, so that we remember
          // that these new callsites came about due to inlining Callee.
          int NewHistoryID = InlineHistory.size();
          InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID));

          for (unsigned i = 0, e = InlineInfo.InlinedCalls.size();
               i != e; ++i) {
            Value *Ptr = InlineInfo.InlinedCalls[i];
            CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID));
          }
        }
      }
      
      // If we inlined or deleted the last possible call site to the function,
      // delete the function body now.
      if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() &&
          // TODO: Can remove if in SCC now.
          !SCCFunctions.count(Callee) &&
          
          // The function may be apparently dead, but if there are indirect
          // callgraph references to the node, we cannot delete it yet, this
          // could invalidate the CGSCC iterator.
          CG[Callee]->getNumReferences() == 0) {
        DEBUG(dbgs() << "    -> Deleting dead function: "
              << Callee->getName() << "\n");
        CallGraphNode *CalleeNode = CG[Callee];
        
        // Remove any call graph edges from the callee to its callees.
        CalleeNode->removeAllCalledFunctions();
        
        // Removing the node for callee from the call graph and delete it.
        delete CG.removeFunctionFromModule(CalleeNode);
        ++NumDeleted;
      }

      // Remove this call site from the list.  If possible, use 
      // swap/pop_back for efficiency, but do not use it if doing so would
      // move a call site to a function in this SCC before the
      // 'FirstCallInSCC' barrier.
      if (SCC.isSingular()) {
        CallSites[CSi] = CallSites.back();
        CallSites.pop_back();
      } else {
        CallSites.erase(CallSites.begin()+CSi);
      }
      --CSi;

      Changed = true;
      LocalChange = true;
    }
  } while (LocalChange);

  return Changed;
}

void WebAssemblyMCInstLower::lower(const MachineInstr *MI,
                                   MCInst &OutMI) const {
  OutMI.setOpcode(MI->getOpcode());

  const MCInstrDesc &Desc = MI->getDesc();
  for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) {
    const MachineOperand &MO = MI->getOperand(I);

    MCOperand MCOp;
    switch (MO.getType()) {
    default:
      MI->print(errs());
      llvm_unreachable("unknown operand type");
    case MachineOperand::MO_MachineBasicBlock:
      MI->print(errs());
      llvm_unreachable("MachineBasicBlock operand should have been rewritten");
    case MachineOperand::MO_Register: {
      // Ignore all implicit register operands.
      if (MO.isImplicit())
        continue;
      const WebAssemblyFunctionInfo &MFI =
          *MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>();
      unsigned WAReg = MFI.getWAReg(MO.getReg());
      MCOp = MCOperand::createReg(WAReg);
      break;
    }
    case MachineOperand::MO_Immediate:
      if (I < Desc.NumOperands) {
        const MCOperandInfo &Info = Desc.OpInfo[I];
        if (Info.OperandType == WebAssembly::OPERAND_TYPEINDEX) {
          MCSymbol *Sym = Printer.createTempSymbol("typeindex");

          SmallVector<wasm::ValType, 4> Returns;
          SmallVector<wasm::ValType, 4> Params;

          const MachineRegisterInfo &MRI =
              MI->getParent()->getParent()->getRegInfo();
          for (const MachineOperand &MO : MI->defs())
            Returns.push_back(getType(MRI.getRegClass(MO.getReg())));
          for (const MachineOperand &MO : MI->explicit_uses())
            if (MO.isReg())
              Params.push_back(getType(MRI.getRegClass(MO.getReg())));

          // call_indirect instructions have a callee operand at the end which
          // doesn't count as a param.
          if (WebAssembly::isCallIndirect(*MI))
            Params.pop_back();

          auto *WasmSym = cast<MCSymbolWasm>(Sym);
          auto Signature = make_unique<wasm::WasmSignature>(std::move(Returns),
                                                            std::move(Params));
          WasmSym->setSignature(Signature.get());
          Printer.addSignature(std::move(Signature));
          WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);

          const MCExpr *Expr = MCSymbolRefExpr::create(
              WasmSym, MCSymbolRefExpr::VK_WASM_TYPEINDEX, Ctx);
          MCOp = MCOperand::createExpr(Expr);
          break;
        }
      }
      MCOp = MCOperand::createImm(MO.getImm());
      break;
    case MachineOperand::MO_FPImmediate: {
      // TODO: MC converts all floating point immediate operands to double.
      // This is fine for numeric values, but may cause NaNs to change bits.
      const ConstantFP *Imm = MO.getFPImm();
      if (Imm->getType()->isFloatTy())
        MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToFloat());
      else if (Imm->getType()->isDoubleTy())
        MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToDouble());
      else
        llvm_unreachable("unknown floating point immediate type");
      break;
    }
    case MachineOperand::MO_GlobalAddress:
      MCOp = lowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
      break;
    case MachineOperand::MO_ExternalSymbol:
      // The target flag indicates whether this is a symbol for a
      // variable or a function.
      assert(MO.getTargetFlags() == 0 &&
             "WebAssembly uses only symbol flags on ExternalSymbols");
      MCOp = lowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
      break;
    case MachineOperand::MO_MCSymbol:
      // This is currently used only for LSDA symbols (GCC_except_table),
      // because global addresses or other external symbols are handled above.
      assert(MO.getTargetFlags() == 0 &&
             "WebAssembly does not use target flags on MCSymbol");
      MCOp = lowerSymbolOperand(MO, MO.getMCSymbol());
      break;
    }

    OutMI.addOperand(MCOp);
  }

  if (!WasmKeepRegisters)
    removeRegisterOperands(MI, OutMI);
}

/// EmitSchedule - Emit the machine code in scheduled order. Return the new
/// InsertPos and MachineBasicBlock that contains this insertion
/// point. ScheduleDAGSDNodes holds a BB pointer for convenience, but this does
/// not necessarily refer to returned BB. The emitter may split blocks.
MachineBasicBlock *ScheduleDAGSDNodes::
EmitSchedule(MachineBasicBlock::iterator &InsertPos) {
  InstrEmitter Emitter(BB, InsertPos);
  DenseMap<SDValue, unsigned> VRBaseMap;
  DenseMap<SUnit*, unsigned> CopyVRBaseMap;
  SmallVector<std::pair<unsigned, MachineInstr*>, 32> Orders;
  SmallSet<unsigned, 8> Seen;
  bool HasDbg = DAG->hasDebugValues();

  // If this is the first BB, emit byval parameter dbg_value's.
  if (HasDbg && BB->getParent()->begin() == MachineFunction::iterator(BB)) {
    SDDbgInfo::DbgIterator PDI = DAG->ByvalParmDbgBegin();
    SDDbgInfo::DbgIterator PDE = DAG->ByvalParmDbgEnd();
    for (; PDI != PDE; ++PDI) {
      MachineInstr *DbgMI= Emitter.EmitDbgValue(*PDI, VRBaseMap);
      if (DbgMI)
        BB->insert(InsertPos, DbgMI);
    }
  }

  for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
    SUnit *SU = Sequence[i];
    if (!SU) {
      // Null SUnit* is a noop.
      TII->insertNoop(*Emitter.getBlock(), InsertPos);
      continue;
    }

    // For pre-regalloc scheduling, create instructions corresponding to the
    // SDNode and any glued SDNodes and append them to the block.
    if (!SU->getNode()) {
      // Emit a copy.
      EmitPhysRegCopy(SU, CopyVRBaseMap, InsertPos);
      continue;
    }

    SmallVector<SDNode *, 4> GluedNodes;
    for (SDNode *N = SU->getNode()->getGluedNode(); N;
         N = N->getGluedNode())
      GluedNodes.push_back(N);
    while (!GluedNodes.empty()) {
      SDNode *N = GluedNodes.back();
      Emitter.EmitNode(GluedNodes.back(), SU->OrigNode != SU, SU->isCloned,
                       VRBaseMap);
      // Remember the source order of the inserted instruction.
      if (HasDbg)
        ProcessSourceNode(N, DAG, Emitter, VRBaseMap, Orders, Seen);
      GluedNodes.pop_back();
    }
    Emitter.EmitNode(SU->getNode(), SU->OrigNode != SU, SU->isCloned,
                     VRBaseMap);
    // Remember the source order of the inserted instruction.
    if (HasDbg)
      ProcessSourceNode(SU->getNode(), DAG, Emitter, VRBaseMap, Orders,
                        Seen);
  }

  // Insert all the dbg_values which have not already been inserted in source
  // order sequence.
  if (HasDbg) {
    MachineBasicBlock::iterator BBBegin = BB->getFirstNonPHI();

    // Sort the source order instructions and use the order to insert debug
    // values.
    std::sort(Orders.begin(), Orders.end(), OrderSorter());

    SDDbgInfo::DbgIterator DI = DAG->DbgBegin();
    SDDbgInfo::DbgIterator DE = DAG->DbgEnd();
    // Now emit the rest according to source order.
    unsigned LastOrder = 0;
    for (unsigned i = 0, e = Orders.size(); i != e && DI != DE; ++i) {
      unsigned Order = Orders[i].first;
      MachineInstr *MI = Orders[i].second;
      // Insert all SDDbgValue's whose order(s) are before "Order".
      if (!MI)
        continue;
      for (; DI != DE &&
             (*DI)->getOrder() >= LastOrder && (*DI)->getOrder() < Order; ++DI) {
        if ((*DI)->isInvalidated())
          continue;
        MachineInstr *DbgMI = Emitter.EmitDbgValue(*DI, VRBaseMap);
        if (DbgMI) {
          if (!LastOrder)
            // Insert to start of the BB (after PHIs).
            BB->insert(BBBegin, DbgMI);
          else {
            // Insert at the instruction, which may be in a different
            // block, if the block was split by a custom inserter.
            MachineBasicBlock::iterator Pos = MI;
            MI->getParent()->insert(llvm::next(Pos), DbgMI);
          }
        }
      }
      LastOrder = Order;
    }
    // Add trailing DbgValue's before the terminator. FIXME: May want to add
//.........这里部分代码省略.........

void PathDiagnosticConsumer::HandlePathDiagnostic(PathDiagnostic *D) {
  OwningPtr<PathDiagnostic> OwningD(D);
  
  if (!D || D->path.empty())
    return;
  
  // We need to flatten the locations (convert Stmt* to locations) because
  // the referenced statements may be freed by the time the diagnostics
  // are emitted.
  D->flattenLocations();

  // If the PathDiagnosticConsumer does not support diagnostics that
  // cross file boundaries, prune out such diagnostics now.
  if (!supportsCrossFileDiagnostics()) {
    // Verify that the entire path is from the same FileID.
    FileID FID;
    const SourceManager &SMgr = (*D->path.begin())->getLocation().getManager();
    SmallVector<const PathPieces *, 5> WorkList;
    WorkList.push_back(&D->path);

    while (!WorkList.empty()) {
      const PathPieces &path = *WorkList.back();
      WorkList.pop_back();

      for (PathPieces::const_iterator I = path.begin(), E = path.end();
           I != E; ++I) {
        const PathDiagnosticPiece *piece = I->getPtr();
        FullSourceLoc L = piece->getLocation().asLocation().getExpansionLoc();
      
        if (FID.isInvalid()) {
          FID = SMgr.getFileID(L);
        } else if (SMgr.getFileID(L) != FID)
          return; // FIXME: Emit a warning?
      
        // Check the source ranges.
        ArrayRef<SourceRange> Ranges = piece->getRanges();
        for (ArrayRef<SourceRange>::iterator I = Ranges.begin(),
                                             E = Ranges.end(); I != E; ++I) {
          SourceLocation L = SMgr.getExpansionLoc(I->getBegin());
          if (!L.isFileID() || SMgr.getFileID(L) != FID)
            return; // FIXME: Emit a warning?
          L = SMgr.getExpansionLoc(I->getEnd());
          if (!L.isFileID() || SMgr.getFileID(L) != FID)
            return; // FIXME: Emit a warning?
        }
        
        if (const PathDiagnosticCallPiece *call =
            dyn_cast<PathDiagnosticCallPiece>(piece)) {
          WorkList.push_back(&call->path);
        }
        else if (const PathDiagnosticMacroPiece *macro =
                 dyn_cast<PathDiagnosticMacroPiece>(piece)) {
          WorkList.push_back(&macro->subPieces);
        }
      }
    }
    
    if (FID.isInvalid())
      return; // FIXME: Emit a warning?
  }  

  // Profile the node to see if we already have something matching it
  llvm::FoldingSetNodeID profile;
  D->Profile(profile);
  void *InsertPos = 0;

  if (PathDiagnostic *orig = Diags.FindNodeOrInsertPos(profile, InsertPos)) {
    // Keep the PathDiagnostic with the shorter path.
    // Note, the enclosing routine is called in deterministic order, so the
    // results will be consistent between runs (no reason to break ties if the
    // size is the same).
    const unsigned orig_size = orig->full_size();
    const unsigned new_size = D->full_size();
    if (orig_size <= new_size)
      return;

    assert(orig != D);
    Diags.RemoveNode(orig);
    delete orig;
  }
  
  Diags.InsertNode(OwningD.take());
}

//.........这里部分代码省略.........
      }
    }

    // Ignore stub implementations.
    if (auto ctor = dyn_cast<ConstructorDecl>(decl)) {
      if (ctor->hasStubImplementation())
        return false;
    }

    // Check access.
    if (!(options & NL_IgnoreAccessibility))
      if (auto VD = dyn_cast<ValueDecl>(decl))
        return VD->isAccessibleFrom(this);

    return true;
  };

  ReferencedNameTracker *tracker = nullptr;
  if (auto containingSourceFile = dyn_cast<SourceFile>(getModuleScopeContext()))
    tracker = containingSourceFile->getReferencedNameTracker();

  bool isLookupCascading;
  if (tracker) {
    if (auto maybeLookupCascade = checkLookupCascading())
      isLookupCascading = maybeLookupCascade.getValue();
    else
      tracker = nullptr;
  }

  // Visit all of the nominal types we know about, discovering any others
  // we need along the way.
  while (!stack.empty()) {
    auto current = stack.back();
    stack.pop_back();

    if (tracker)
      tracker->addUsedMember({current, member.getBaseName()},isLookupCascading);

    // Make sure we've resolved implicit constructors, if we need them.
    if (member.getBaseName() == ctx.Id_init && typeResolver)
      typeResolver->resolveImplicitConstructors(current);

    // Look for results within the current nominal type and its extensions.
    bool currentIsProtocol = isa<ProtocolDecl>(current);
    for (auto decl : current->lookupDirect(member)) {
      // If we're performing a type lookup, don't even attempt to validate
      // the decl if its not a type.
      if ((options & NL_OnlyTypes) && !isa<TypeDecl>(decl))
        continue;

      // Resolve the declaration signature when we find the
      // declaration.
      if (typeResolver && !decl->isBeingTypeChecked()) {
        typeResolver->resolveDeclSignature(decl);

        if (!decl->hasType())
          continue;
      }

      if (isAcceptableDecl(current, decl))
        decls.push_back(decl);
    }

    // If we're not supposed to visit our supertypes, we're done.
    if ((options & NL_VisitSupertypes) == 0)
      continue;