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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/Bitcode/ReaderWriter.h"
17 #include "llvm/IR/Constants.h"
18 #include "llvm/IR/DerivedTypes.h"
19 #include "llvm/IR/Instructions.h"
20 #include "llvm/IR/LLVMContext.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/Support/raw_ostream.h"
23 using namespace llvm;
24 
main()25 int main() {
26   LLVMContext Context;
27 
28   // Create the "module" or "program" or "translation unit" to hold the
29   // function
30   Module *M = new Module("test", Context);
31 
32   // Create the main function: first create the type 'int ()'
33   FunctionType *FT =
34     FunctionType::get(Type::getInt32Ty(Context), /*not vararg*/false);
35 
36   // By passing a module as the last parameter to the Function constructor,
37   // it automatically gets appended to the Module.
38   Function *F = Function::Create(FT, Function::ExternalLinkage, "main", M);
39 
40   // Add a basic block to the function... again, it automatically inserts
41   // because of the last argument.
42   BasicBlock *BB = BasicBlock::Create(Context, "EntryBlock", F);
43 
44   // Get pointers to the constant integers...
45   Value *Two = ConstantInt::get(Type::getInt32Ty(Context), 2);
46   Value *Three = ConstantInt::get(Type::getInt32Ty(Context), 3);
47 
48   // Create the add instruction... does not insert...
49   Instruction *Add = BinaryOperator::Create(Instruction::Add, Two, Three,
50                                             "addresult");
51 
52   // explicitly insert it into the basic block...
53   BB->getInstList().push_back(Add);
54 
55   // Create the return instruction and add it to the basic block
56   BB->getInstList().push_back(ReturnInst::Create(Context, Add));
57 
58   // Output the bitcode file to stdout
59   WriteBitcodeToFile(M, outs());
60 
61   // Delete the module and all of its contents.
62   delete M;
63   return 0;
64 }
65