如何使用opt打印循环信息？

#include <llvm/IR/Function.h>
#include <llvm/IR/IRBuilder.h>
#include <llvm/IR/LLVMContext.h>
#include <llvm/IR/Module.h>
#include <llvm/IR/Verifier.h>
#include <llvm/Support/raw_ostream.h>

using namespace llvm;

int main() {
  LLVMContext Context;
  Module M("example", Context);
  IRBuilder<> Builder(Context);

  // 创建一个函数
  FunctionType *FuncType = FunctionType::get(Type::getVoidTy(Context), false);
  Function *Func =
      Function::Create(FuncType, Function::ExternalLinkage, "foo", M);

  // 创建一个基本块
  BasicBlock *BB = BasicBlock::Create(Context, "entry", Func);
  Builder.SetInsertPoint(BB);

  // 创建一个循环
  BasicBlock *LoopBB = BasicBlock::Create(Context, "loop", Func);
  Builder.CreateBr(LoopBB);
  Builder.SetInsertPoint(LoopBB);

  // 在循环中添加一些指令
  Value *Counter = Builder.CreateAlloca(Type::getInt32Ty(Context));
  Builder.CreateStore(ConstantInt::get(Type::getInt32Ty(Context), 0), Counter);
  Value *Condition =
      Builder.CreateICmpSLT(Builder.CreateLoad(Counter), ConstantInt::get(Type::getInt32Ty(Context), 10));
  BasicBlock *LoopBodyBB = BasicBlock::Create(Context, "loop.body", Func);
  BasicBlock *AfterLoopBB = BasicBlock::Create(Context, "afterloop", Func);
  Builder.CreateCondBr(Condition, LoopBodyBB, AfterLoopBB);

  Builder.SetInsertPoint(LoopBodyBB);
  Builder.CreateStore(Builder.CreateAdd(Builder.CreateLoad(Counter), ConstantInt::get(Type::getInt32Ty(Context), 1)), Counter);
  Builder.CreateBr(LoopBB);

  // 在循环后面添加一些指令
  Builder.SetInsertPoint(AfterLoopBB);
  Builder.CreateRetVoid();

  // 验证IR的正确性
  verifyModule(M, &errs());

  // 打印循环信息
  PassRegistry &Registry = *PassRegistry::getPassRegistry();
  initializeLoopInfoPass(Registry);
  FunctionPassManager FPM(&M);
  FPM.add(createLoopInfoWrapperPass());
  FPM.run(*Func);

  return 0;
}