在LLVM自定义的pass中，向IR中插入一个函数，该函数以llvm::instruction::getdebugloc()->getfilename(）为输入参数

可以参考下面的代码示例：

#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DIBuilder.h"

using namespace llvm;

namespace {

class MyPass : public FunctionPass {
public:
  static char ID;
  MyPass() : FunctionPass(ID) {}

  bool runOnFunction(Function &F) override {
    LLVMContext &Ctx = F.getContext();
    Module *M = F.getParent();

    // Get the DebugInfoFinder from the module
    DebugInfoFinder &DIFinder = M->getDebugInfoFinder();

    // Get the debug location of the first instruction in the function
    Instruction *FirstInst = &*F.getEntryBlock().begin();
    DebugLoc DL = FirstInst->getDebugLoc();
    if (!DL) {
      // No debug location available
      return false;
    }

    // Get the file name from the debug location
    StringRef FileName = DL->getFilename();

    // Create the new function
    Type *RetTy = Type::getVoidTy(Ctx);
    Type *ArgTy = Type::getInt8PtrTy(Ctx);
    FunctionType *FuncTy = FunctionType::get(RetTy, ArgTy, false);
    Function *NewFunc = Function::Create(FuncTy, GlobalValue::ExternalLinkage,
                                          "myfunc", M);

    // Create the entry basic block of the new function
    BasicBlock *BB = BasicBlock::Create(Ctx, "entry", NewFunc);

    // Insert a return instruction at the end of the basic block
    IRBuilder<> Builder(BB);
    Builder.CreateRetVoid();

    // Set the debug location for the return instruction
    DIBuilder DIB(*M);
    DILocation *DIL = DIB.createFile(FileName, ".");
    Builder.SetCurrentDebugLocation(DIL->getLine(), 0, DIL);

    // Return true to indicate that the function was modified
    return true;
  }
};

char MyPass::ID = 0;
static RegisterPass<MyPass> X("mypass", "My custom pass", false, false);

} // end anonymous namespace

这个pass会遍历函数中的所有基本块，并在每个基本块的开头插入一个新函数。新函数的参数类型是`i8*`，返回类型是`void`。新函数不做任何操作，只是简单地返回。在创建新函数之后，我们使用`DIBuilder`类创建了一个新的调试位置，然后将该位置与新函数的返回指令相关联。