ModuleMaker.cpp revision b461131c99d79a4e7f1cf01bd5ef4a98b169af96 
1//===- examples/ModuleMaker/ModuleMaker.cpp - Example project ---*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This programs is a simple example that creates an LLVM module "from scratch",
11// emitting it as a bytecode file to standard out.  This is just to show how
12// LLVM projects work and to demonstrate some of the LLVM APIs.
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/Module.h"
17#include "llvm/DerivedTypes.h"
18#include "llvm/Constants.h"
19#include "llvm/Instructions.h"
20#include "llvm/Bytecode/Writer.h"
21#include <iostream>
22
23using namespace llvm;
24
25int main() {
26  // Create the "module" or "program" or "translation unit" to hold the
27  // function
28  Module *M = new Module("test");
29
30  // Create the main function: first create the type 'int ()'
31  FunctionType *FT = FunctionType::get(Type::IntTy, std::vector<const Type*>(),
32                                       /*not vararg*/false);
33
34  // By passing a module as the last parameter to the Function constructor,
35  // it automatically gets appended to the Module.
36  Function *F = new Function(FT, Function::ExternalLinkage, "main", M);
37
38  // Add a basic block to the function... again, it automatically inserts
39  // because of the last argument.
40  BasicBlock *BB = new BasicBlock("EntryBlock", F);
41
42  // Get pointers to the constant integers...
43  Value *Two = ConstantSInt::get(Type::IntTy, 2);
44  Value *Three = ConstantSInt::get(Type::IntTy, 3);
45
46  // Create the add instruction... does not insert...
47  Instruction *Add = BinaryOperator::create(Instruction::Add, Two, Three,
48                                            "addresult");
49
50  // explicitly insert it into the basic block...
51  BB->getInstList().push_back(Add);
52
53  // Create the return instruction and add it to the basic block
54  BB->getInstList().push_back(new ReturnInst(Add));
55
56  // Output the bytecode file to stdout
57  try {
58    WriteBytecodeToFile(M, std::cout);
59  } catch (const std::string &Error) {
60    std::cerr << "Error writing file: " << Error << "\n";
61    return 1;
62  }
63
64  // Delete the module and all of its contents.
65  delete M;
66  return 0;
67}
68