C++ SmallPtrSetImpl::count方法代码示例

// Is any successor of BB in the LiveIn set?
static bool successorHasLiveIn(SILBasicBlock *BB,
                               llvm::SmallPtrSetImpl<SILBasicBlock *> &LiveIn) {
  for (auto &Succ : BB->getSuccessors())
    if (LiveIn.count(Succ))
      return true;

  return false;
}

void ModuleManager::removeModules(
    ModuleIterator first, ModuleIterator last,
    llvm::SmallPtrSetImpl<ModuleFile *> &LoadedSuccessfully,
    ModuleMap *modMap) {
  if (first == last)
    return;

  // Collect the set of module file pointers that we'll be removing.
  llvm::SmallPtrSet<ModuleFile *, 4> victimSet(first, last);

  auto IsVictim = [&](ModuleFile *MF) {
    return victimSet.count(MF);
  };
  // Remove any references to the now-destroyed modules.
  for (unsigned i = 0, n = Chain.size(); i != n; ++i) {
    Chain[i]->ImportedBy.remove_if(IsVictim);
  }
  Roots.erase(std::remove_if(Roots.begin(), Roots.end(), IsVictim),
              Roots.end());

  // Delete the modules and erase them from the various structures.
  for (ModuleIterator victim = first; victim != last; ++victim) {
    Modules.erase((*victim)->File);

    if (modMap) {
      StringRef ModuleName = (*victim)->ModuleName;
      if (Module *mod = modMap->findModule(ModuleName)) {
        mod->setASTFile(nullptr);
      }
    }

    // Files that didn't make it through ReadASTCore successfully will be
    // rebuilt (or there was an error). Invalidate them so that we can load the
    // new files that will be renamed over the old ones.
    if (LoadedSuccessfully.count(*victim) == 0)
      FileMgr.invalidateCache((*victim)->File);

    delete *victim;
  }

  // Remove the modules from the chain.
  Chain.erase(first, last);
}

/// \brief Issue an "unreachable code" diagnostic if the blocks contains or
/// leads to another block that contains user code.
///
/// Note, we rely on SILLocation information to determine if SILInstructions
/// correspond to user code.
static bool diagnoseUnreachableBlock(const SILBasicBlock &B,
                                     SILModule &M,
                                     const SILBasicBlockSet &Reachable,
                                     UnreachableUserCodeReportingState *State,
                                     const SILBasicBlock *TopLevelB,
                         llvm::SmallPtrSetImpl<const SILBasicBlock*> &Visited){
  if (Visited.count(&B))
    return false;
  Visited.insert(&B);
  
  assert(State);
  for (auto I = B.begin(), E = B.end(); I != E; ++I) {
    SILLocation Loc = I->getLoc();
    // If we've reached an implicit return, we have not found any user code and
    // can stop searching for it.
    if (Loc.is<ImplicitReturnLocation>() || Loc.isAutoGenerated())
      return false;

    // Check if the instruction corresponds to user-written code, also make
    // sure we don't report an error twice for the same instruction.
    if (isUserCode(&*I) && !State->BlocksWithErrors.count(&B)) {

      // Emit the diagnostic.
      auto BrInfoIter = State->MetaMap.find(TopLevelB);
      assert(BrInfoIter != State->MetaMap.end());
      auto BrInfo = BrInfoIter->second;

      switch (BrInfo.Kind) {
      case (UnreachableKind::FoldedBranch):
        // Emit the diagnostic on the unreachable block and emit the
        // note on the branch responsible for the unreachable code.
        diagnose(M.getASTContext(), Loc.getSourceLoc(), diag::unreachable_code);
        diagnose(M.getASTContext(), BrInfo.Loc.getSourceLoc(),
                 diag::unreachable_code_branch, BrInfo.CondIsAlwaysTrue);
        break;

      case (UnreachableKind::FoldedSwitchEnum): {
        // If we are warning about a switch condition being a constant, the main
        // emphasis should be on the condition (to ensure we have a single
        // message per switch).
        const SwitchStmt *SS = BrInfo.Loc.getAsASTNode<SwitchStmt>();
        if (!SS)
          break;
        assert(SS);
        const Expr *SE = SS->getSubjectExpr();
        diagnose(M.getASTContext(), SE->getLoc(), diag::switch_on_a_constant);
        diagnose(M.getASTContext(), Loc.getSourceLoc(),
                 diag::unreachable_code_note);
        break;
      }

      case (UnreachableKind::NoreturnCall): {
        // Specialcase when we are warning about unreachable code after a call
        // to a noreturn function.
        if (!BrInfo.Loc.isASTNode<ExplicitCastExpr>()) {
          assert(BrInfo.Loc.isASTNode<ApplyExpr>());
          diagnose(M.getASTContext(), Loc.getSourceLoc(),
                   diag::unreachable_code);
          diagnose(M.getASTContext(), BrInfo.Loc.getSourceLoc(),
                   diag::call_to_noreturn_note);
        }
        break;
      }
      }

      // Record that we've reported this unreachable block to avoid duplicates
      // in the future.
      State->BlocksWithErrors.insert(&B);
      return true;
    }
  }

  // This block could be empty if it's terminator has been folded.
  if (B.empty())
    return false;

  // If we have not found user code in this block, inspect it's successors.
  // Check if at least one of the successors contains user code.
  for (auto I = B.succ_begin(), E = B.succ_end(); I != E; ++I) {
    SILBasicBlock *SB = *I;
    bool HasReachablePred = false;
    for (auto PI = SB->pred_begin(), PE = SB->pred_end(); PI != PE; ++PI) {
      if (Reachable.count(*PI))
        HasReachablePred = true;
    }

    // If all of the predecessors of this successor are unreachable, check if
    // it contains user code.
    if (!HasReachablePred && diagnoseUnreachableBlock(*SB, M, Reachable,
                                                    State, TopLevelB, Visited))
      return true;
  }
  
  return false;
}