Finding a variable name while using LLVM Interpreter

Question

When using LLVM Interpreter(Aka lli), an Instruction object is run in Interpreter::run() function like as in the code.

void Interpreter::run() {
    while (!ECStack.empty()) {
    // Interpret a single instruction & increment the "PC".
    ExecutionContext &SF = ECStack.back();  // Current stack frame
    Instruction &I = *SF.CurInst++;         // Increment before execute

    // Track the number of dynamic instructions executed.
    ++NumDynamicInsts;
    DEBUG(dbgs() << "About to interpret: " << I << "\n");

    visit(I);   // Dispatch to one of the visit* methods...
  }
}

A line with DEBUG preprocessor will print the instruction that was written in .ll file like this.

About to interpret: %retval = alloca i32, align 4

How can I get the LLVM IR variable's name?

In this situation it will be %retval.