LLVM_Template - modified slightly from the example in http://llvm.org/docs/ProgrammersManual.html

llvm_template.cpp

// From http://llvm.org/docs/ProgrammersManual.html
#include "llvm/Pass.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

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

    virtual bool doInitialization(Module &M) {
      return false;
    }

    virtual bool doFinalization(Module &M) {
      return false;
    }
    
    bool runOnFunction(Function &F) override {
        errs() << "Hello: ";
        errs().write_escaped(F.getName()) << '\n';
        return false;
    }
}; // end of struct Hello
}

char Hello::ID = 0;
static RegisterPass<Hello> X("hello", "Hello World Pass",
                             false /* Only looks at CFG */,
false /* Analysis Pass */);