ModuleMaker.cpp revision 7cbd8a3e92221437048b484d5ef9c0a22d0f8c58 
1//===- examples/ModuleMaker/ModuleMaker.cpp - Example project ---*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// 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 bitcode 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/Bitcode/ReaderWriter.h"
21#include <iostream>
22using namespace llvm;
23
24int main() {
25  // Create the "module" or "program" or "translation unit" to hold the
26  // function
27  Module *M = new Module("test");
28
29  // Create the main function: first create the type 'int ()'
30  FunctionType *FT = FunctionType::get(Type::Int32Ty, std::vector<const Type*>(),
31                                       /*not vararg*/false);
32
33  // By passing a module as the last parameter to the Function constructor,
34  // it automatically gets appended to the Module.
35  Function *F = Function::Create(FT, Function::ExternalLinkage, "main", M);
36
37  // Add a basic block to the function... again, it automatically inserts
38  // because of the last argument.
39  BasicBlock *BB = BasicBlock::Create("EntryBlock", F);
40
41  // Get pointers to the constant integers...
42  Value *Two = ConstantInt::get(Type::Int32Ty, 2);
43  Value *Three = ConstantInt::get(Type::Int32Ty, 3);
44
45  // Create the add instruction... does not insert...
46  Instruction *Add = BinaryOperator::Create(Instruction::Add, Two, Three,
47                                            "addresult");
48
49  // explicitly insert it into the basic block...
50  BB->getInstList().push_back(Add);
51
52  // Create the return instruction and add it to the basic block
53  BB->getInstList().push_back(ReturnInst::Create(Add));
54
55  // Output the bitcode file to stdout
56  WriteBitcodeToFile(M, std::cout);
57
58  // Delete the module and all of its contents.
59  delete M;
60  return 0;
61}
62