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A Minimal LLVM JIT example for LLVM-5
jit-toy: jit-toy.cpp
clang++ -g -o $@ $^ $(shell /usr/lib/llvm-5.0/bin/llvm-config --cxxflags --ldflags --system-libs --libs core)
#include <llvm/IR/IRBuilder.h>
#include <llvm/Support/TargetSelect.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/ExecutionEngine/JITSymbol.h>
#include <llvm/ExecutionEngine/SectionMemoryManager.h>
#include <llvm/ExecutionEngine/Orc/CompileUtils.h>
#include <llvm/ExecutionEngine/Orc/IRCompileLayer.h>
#include <llvm/ExecutionEngine/Orc/LambdaResolver.h>
#include <llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h>
#include <memory>
#include <vector>
using namespace llvm;
using namespace std;
static Module* jit_module = NULL;
static LLVMContext context;
static IRBuilder<> builder(context);
using LinkLayer = orc::RTDyldObjectLinkingLayer;
using Compiler = orc::SimpleCompiler;
using CompileLayer = orc::IRCompileLayer<LinkLayer, Compiler>;
JITSymbol dummy_lookup(const string& name)
{
return JITSymbol(NULL);
}
void code_gen()
{
jit_module = new Module("Test JIT Compiler", context);
// (double, double, double)
std::vector<Type*> param_type(3, Type::getDoubleTy(context));
// double (*)(double, double, double)
FunctionType* prototype = FunctionType::get(Type::getDoubleTy(context), param_type, false);
Function *func = Function::Create(prototype, Function::ExternalLinkage, "test_func", jit_module);
BasicBlock *body = BasicBlock::Create(context, "body", func);
builder.SetInsertPoint(body);
std::vector<Value*> args;
for(auto& arg : func->args())
args.push_back(&arg);
Value* temp = builder.CreateFMul(args[0], args[1], "temp");
Value* ret = builder.CreateFMul(args[2], temp, "result");
builder.CreateRet(ret);
}
int main()
{
// Initialization
LLVMInitializeNativeTarget();
InitializeNativeTargetAsmPrinter();
TargetMachine* target = EngineBuilder().selectTarget();
// Emit the LLVM IR to the Module
code_gen();
// Compile the IR to Machine Code
const DataLayout dl = target->createDataLayout();
LinkLayer link_layer([]() { return std::make_shared<SectionMemoryManager>(); });
CompileLayer compile_layer(link_layer, Compiler(*target));
auto jit_module_handle = cantFail(compile_layer.addModule(std::shared_ptr<Module>(jit_module),
orc::createLambdaResolver(dummy_lookup, dummy_lookup)));
// Run the compiled function !
JITSymbol symbol = compile_layer.findSymbolIn(jit_module_handle, "test_func", false);
double (*native_func)(double, double, double) = (decltype(native_func))cantFail(symbol.getAddress());
printf("%lf\n", native_func(3,4,5));
printf("%lf\n", native_func(1,2,3));
delete target;
return 0;
}
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