1 //===- examples/ModuleMaker/ModuleMaker.cpp - Example project ---*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This programs is a simple example that creates an LLVM module "from scratch",
10 // emitting it as a bitcode file to standard out. This is just to show how
11 // LLVM projects work and to demonstrate some of the LLVM APIs.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/Bitcode/BitcodeWriter.h"
16 #include "llvm/IR/BasicBlock.h"
17 #include "llvm/IR/Constants.h"
18 #include "llvm/IR/DerivedTypes.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/IR/InstrTypes.h"
21 #include "llvm/IR/Instruction.h"
22 #include "llvm/IR/Instructions.h"
23 #include "llvm/IR/LLVMContext.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/IR/Type.h"
26 #include "llvm/Support/raw_ostream.h"
27
28 using namespace llvm;
29
main()30 int main() {
31 LLVMContext Context;
32
33 // Create the "module" or "program" or "translation unit" to hold the
34 // function
35 Module *M = new Module("test", Context);
36
37 // Create the main function: first create the type 'int ()'
38 FunctionType *FT =
39 FunctionType::get(Type::getInt32Ty(Context), /*not vararg*/false);
40
41 // By passing a module as the last parameter to the Function constructor,
42 // it automatically gets appended to the Module.
43 Function *F = Function::Create(FT, Function::ExternalLinkage, "main", M);
44
45 // Add a basic block to the function... again, it automatically inserts
46 // because of the last argument.
47 BasicBlock *BB = BasicBlock::Create(Context, "EntryBlock", F);
48
49 // Get pointers to the constant integers...
50 Value *Two = ConstantInt::get(Type::getInt32Ty(Context), 2);
51 Value *Three = ConstantInt::get(Type::getInt32Ty(Context), 3);
52
53 // Create the add instruction... does not insert...
54 Instruction *Add = BinaryOperator::Create(Instruction::Add, Two, Three,
55 "addresult");
56
57 // explicitly insert it into the basic block...
58 BB->getInstList().push_back(Add);
59
60 // Create the return instruction and add it to the basic block
61 BB->getInstList().push_back(ReturnInst::Create(Context, Add));
62
63 // Output the bitcode file to stdout
64 WriteBitcodeToFile(*M, outs());
65
66 // Delete the module and all of its contents.
67 delete M;
68 return 0;
69 }
70