如何在LLVM中获得两条指令之间的距离？

#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/InstIterator.h"
#include <iostream>

using namespace llvm;

int getDistanceBetweenInstructions(Instruction* inst1, Instruction* inst2) {
    BasicBlock* bb1 = inst1->getParent();
    BasicBlock* bb2 = inst2->getParent();

    if (bb1 != bb2) {
        // If the instructions are in different basic blocks, return -1
        return -1;
    }

    int distance = 0;
    for (auto it = inst_begin(bb1), e = inst_end(bb1); it != e; ++it) {
        Instruction* inst = &*it;
        if (inst == inst1) {
            // Found the first instruction
            break;
        }
        if (inst == inst2) {
            // Found the second instruction before the first instruction
            return -1;
        }
        distance++;
    }

    return distance;
}

int main() {
    LLVMContext context;
    Module module("example", context);
    FunctionType* funcType = FunctionType::get(Type::getVoidTy(context), false);
    Function* function = Function::Create(funcType, Function::ExternalLinkage, "test", module);

    BasicBlock* entry = BasicBlock::Create(context, "entry", function);
    IRBuilder<> builder(context);
    builder.SetInsertPoint(entry);

    // Create some instructions
    Value* a = builder.CreateAlloca(Type::getInt32Ty(context));
    Value* b = builder.CreateAlloca(Type::getInt32Ty(context));
    Value* c = builder.CreateAlloca(Type::getInt32Ty(context));

    // Get the distance between instructions
    int distance = getDistanceBetweenInstructions(cast<Instruction>(a), cast<Instruction>(c));
    std::cout << "Distance: " << distance << std::endl;

    return 0;
}