compile.sh

#!/bin/zsh
g++ `llvm-config --cxxflags --ldflags --libs --system-libs` main.cpp -o test

llvm.c

#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/SourceMgr.h"

static llvm::LLVMContext TheContext;
static llvm::IRBuilder<> Builder(TheContext);
static std::unique_ptr<llvm::Module> TheModule;

int main() {
    TheModule = std::make_unique<llvm::Module>("top", TheContext);
    llvm::Function* mainFunc = llvm::Function::Create(
            llvm::FunctionType::get(llvm::Type::getInt32Ty(TheContext), false),
            llvm::Function::ExternalLinkage, "main", TheModule.get());
    Builder.SetInsertPoint(llvm::BasicBlock::Create(TheContext, "entry", mainFunc));
    llvm::Value* a = Builder.CreateAlloca(Builder.getInt32Ty(), nullptr, "a");
    llvm::Value* b = Builder.CreateAlloca(Builder.getInt32Ty(), nullptr, "b");
    Builder.CreateStore(Builder.getInt32(32), a);
    Builder.CreateStore(Builder.CreateAdd(Builder.CreateLoad(a), Builder.getInt32(8)), b);
    Builder.CreateRet(Builder.CreateAdd(Builder.CreateLoad(a), Builder.CreateLoad(b)));
    TheModule->print(llvm::errs(), nullptr);
    return 0;
}