C++ (Cpp) SILFunction::getBlocks示例

static bool removeUnreachableBlocks(SILFunction &F, SILModule &M,
                                    UnreachableUserCodeReportingState *State) {
  if (F.empty())
    return false;

  SILBasicBlockSet Reachable;
  SmallVector<SILBasicBlock*, 128> Worklist;
  Worklist.push_back(&F.front());
  Reachable.insert(&F.front());

  // Collect all reachable blocks by walking the successors.
  do {
    SILBasicBlock *BB = Worklist.pop_back_val();
    for (auto SI = BB->succ_begin(), SE = BB->succ_end(); SI != SE; ++SI) {
      if (Reachable.insert(*SI).second)
        Worklist.push_back(*SI);
    }
  } while (!Worklist.empty());
  assert(Reachable.size() <= F.size());

  // If everything is reachable, we are done.
  if (Reachable.size() == F.size())
    return false;

  // Diagnose user written unreachable code.
  if (State) {
    for (auto BI = State->PossiblyUnreachableBlocks.begin(),
              BE = State->PossiblyUnreachableBlocks.end(); BI != BE; ++BI) {
      const SILBasicBlock *BB = *BI;
      if (!Reachable.count(BB)) {
        llvm::SmallPtrSet<const SILBasicBlock *, 1> visited;
        diagnoseUnreachableBlock(**BI, M, Reachable, State, BB, visited);
      }
    }
  }

  // Remove references from the dead blocks.
  for (auto I = F.begin(), E = F.end(); I != E; ++I) {
    SILBasicBlock *BB = &*I;
    if (Reachable.count(BB))
      continue;

    // Drop references to other blocks.
    recursivelyDeleteTriviallyDeadInstructions(BB->getTerminator(), true);
    NumInstructionsRemoved++;
  }

  // Delete dead instructions and everything that could become dead after
  // their deletion.
  llvm::SmallVector<SILInstruction*, 32> ToBeDeleted;
  for (auto BI = F.begin(), BE = F.end(); BI != BE; ++BI)
    if (!Reachable.count(&*BI))
      for (auto I = BI->begin(), E = BI->end(); I != E; ++I)
        ToBeDeleted.push_back(&*I);
  recursivelyDeleteTriviallyDeadInstructions(ToBeDeleted, true);
  NumInstructionsRemoved += ToBeDeleted.size();

  // Delete the dead blocks.
  for (auto I = F.begin(), E = F.end(); I != E;)
    if (!Reachable.count(&*I)) {
      I = F.getBlocks().erase(I);
      NumBlocksRemoved++;
    } else
      ++I;

  return true;
}