#include "llvm/Pass.h"
#include "llvm/IR/Function.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
using namespace llvm;

#define DEBUG_TYPE "hello"

STATISTIC(HelloCounter, "Counts number of functions greeted");

namespace {
  struct Hello : public FunctionPass {
    static char ID;
    Hello() : FunctionPass(ID) {}

    ~Hello() {
        errs() << "\nCompile Finish!\n";
        errs() << "Functions count: " << HelloCounter;
    }

    bool runOnFunction(Function &F) override {
      ++HelloCounter;
      errs() << "Got Function> ";
      errs().write_escaped(F.getName()) << '\n';
      return false;
    }
  };
}

char Hello::ID = 0;
// 为 opt 注册
static RegisterPass<Hello> X("funcname", "Hello World Pass");
// 为 clang 注册, 在高版本中不可用, 测试在10.0.0版本中可用
static RegisterStandardPasses Y(PassManagerBuilder::EP_EarlyAsPossible,
                                [](const PassManagerBuilder& Builder,
                                   legacy::PassManagerBase& PM) {
                                  PM.add(new Hello());
                                });