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> 22 using namespace llvm; 23 24 int 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, /*not vararg*/false); 31 32 // By passing a module as the last parameter to the Function constructor, 33 // it automatically gets appended to the Module. 34 Function *F = Function::Create(FT, Function::ExternalLinkage, "main", M); 35 36 // Add a basic block to the function... again, it automatically inserts 37 // because of the last argument. 38 BasicBlock *BB = BasicBlock::Create("EntryBlock", F); 39 40 // Get pointers to the constant integers... 41 Value *Two = ConstantInt::get(Type::Int32Ty, 2); 42 Value *Three = ConstantInt::get(Type::Int32Ty, 3); 43 44 // Create the add instruction... does not insert... 45 Instruction *Add = BinaryOperator::Create(Instruction::Add, Two, Three, 46 "addresult"); 47 48 // explicitly insert it into the basic block... 49 BB->getInstList().push_back(Add); 50 51 // Create the return instruction and add it to the basic block 52 BB->getInstList().push_back(ReturnInst::Create(Add)); 53 54 // Output the bitcode file to stdout 55 WriteBitcodeToFile(M, std::cout); 56 57 // Delete the module and all of its contents. 58 delete M; 59 return 0; 60 } 61