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JacquesLucke/llvm_add.cc

Created November 30, 2018 14:54
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  1. JacquesLucke created this gist Nov 30, 2018.
    49 changes: 49 additions & 0 deletions llvm_add.cc
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,49 @@
    #include "llvm/IR/IRBuilder.h"
    #include "llvm/IR/Verifier.h"
    #include "llvm/Support/TargetSelect.h"
    #include "llvm/ExecutionEngine/ExecutionEngine.h"

    #include <vector>
    #include <memory>

    void test_llvm() {
    llvm::LLVMContext *context = new llvm::LLVMContext();
    llvm::Module *module = new llvm::Module("test", *context);

    std::vector<llvm::Type *> arg_types = {
    llvm::Type::getInt32Ty(*context),
    llvm::Type::getInt32Ty(*context)};

    llvm::FunctionType *ftype = llvm::FunctionType::get(
    llvm::Type::getInt32Ty(*context), arg_types, false);

    llvm::Function *func = llvm::Function::Create(
    ftype, llvm::GlobalValue::LinkageTypes::ExternalLinkage, "my_func", module);

    llvm::BasicBlock *bb = llvm::BasicBlock::Create(*context, "entry", func);

    llvm::IRBuilder<> builder(*context);
    builder.SetInsertPoint(bb);

    llvm::Argument *arg0 = func->arg_begin() + 0;
    llvm::Argument *arg1 = func->arg_begin() + 1;

    llvm::Value *result = builder.CreateAdd(arg0, arg1, "result");
    builder.CreateRet(result);

    llvm::verifyFunction(*func, &llvm::outs());
    llvm::verifyModule(*module, &llvm::outs());

    module->print(llvm::outs(), nullptr);

    llvm::InitializeNativeTarget();
    llvm::InitializeNativeTargetAsmPrinter();
    llvm::InitializeNativeTargetAsmParser();

    llvm::ExecutionEngine *ee = llvm::EngineBuilder(std::unique_ptr<llvm::Module>(module)).create();
    ee->finalizeObject();

    int (*add)(int, int) = (int (*)(int, int))ee->getFunctionAddress("my_func");
    printf("Pointer: %p\n", add);
    printf("Result: %d\n", add(43, 10));
    }