llvm-project

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//===- examples/ModuleMaker/ModuleMaker.cpp - Example project ---*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This programs is a simple example that creates an LLVM module "from scratch",
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// emitting it as a bitcode file to standard out.  This is just to show how
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// LLVM projects work and to demonstrate some of the LLVM APIs.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Bitcode/BitcodeWriter.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/InstrTypes.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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int main() {
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  LLVMContext Context;
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  // Create the "module" or "program" or "translation unit" to hold the
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  // function
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  Module *M = new Module("test", Context);
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  // Create the main function: first create the type 'int ()'
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  FunctionType *FT =
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    FunctionType::get(Type::getInt32Ty(Context), /*not vararg*/false);
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  // By passing a module as the last parameter to the Function constructor,
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  // it automatically gets appended to the Module.
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  Function *F = Function::Create(FT, Function::ExternalLinkage, "main", M);
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  // Add a basic block to the function... again, it automatically inserts
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  // because of the last argument.
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  BasicBlock *BB = BasicBlock::Create(Context, "EntryBlock", F);
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  // Get pointers to the constant integers...
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  Value *Two = ConstantInt::get(Type::getInt32Ty(Context), 2);
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  Value *Three = ConstantInt::get(Type::getInt32Ty(Context), 3);
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  // Create the add instruction... does not insert...
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  Instruction *Add = BinaryOperator::Create(Instruction::Add, Two, Three,
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                                            "addresult");
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  // explicitly insert it into the basic block...
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  Add->insertInto(BB, BB->end());
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  // Create the return instruction and add it to the basic block
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  ReturnInst::Create(Context, Add)->insertInto(BB, BB->end());
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  // Output the bitcode file to stdout
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  WriteBitcodeToFile(*M, outs());
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  // Delete the module and all of its contents.
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  delete M;
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  return 0;
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}
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