LLVM [2.6] JIT Tutorial 1 (OS X, 2015)

gistfile1.cpp

// A modified version of the "LLVM JIT Tutorial 1" code from http://goo.gl/1cNfH7
// which actually works with the latest versions of LLVM as of Feb 2015.
//
// To compile if you're on OS X using 'llvm' [libs, etc.] from Homebrew:
// 	clang++ -g test.cpp `/usr/local/opt/llvm/bin/llvm-config --cxxflags --ldflags --libs core --system-libs` -I/usr/local/opt/llvm/include -o test

#include "llvm/IR/Module.h"
#include "llvm/IR/Function.h"
#include "llvm/PassManager.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/Verifier.h"
#include "llvm/IR/IRPrintingPasses.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

Module* makeLLVMModule() {
	LLVMContext &context = getGlobalContext();
	
	// Module Construction
	Module* mod = new Module("test", context);
	Constant* c = mod->getOrInsertFunction("mul_add",
	/*ret type*/                           IntegerType::get(context, 32),
	/*args*/                               IntegerType::get(context, 32),
	                                       IntegerType::get(context, 32),
	                                       IntegerType::get(context, 32),
	/*varargs terminated with null*/       NULL);

	Function* mul_add = cast<Function>(c);
	mul_add->setCallingConv(CallingConv::C);
	Function::arg_iterator args = mul_add->arg_begin();
	Value* x = args++;
	x->setName("x");
	Value* y = args++;
	y->setName("y");
	Value* z = args++;
	z->setName("z");

	BasicBlock* block = BasicBlock::Create(context, "entry", mul_add);
	IRBuilder<> builder(block);
	Value* tmp = builder.CreateBinOp(Instruction::Mul, x, y, "tmp");
	Value* tmp2 = builder.CreateBinOp(Instruction::Add, tmp, z, "tmp2");

	builder.CreateRet(tmp2);

	return mod;
}

int main(int argc, char**argv) {
	Module* Mod = makeLLVMModule();

	verifyModule(*Mod, &outs());

	PassManager PM;
	PM.add(createPrintModulePass(outs()));
	PM.run(*Mod);

	delete Mod;
	return 0;
}