main.cpp

#include <llvm-c/Core.h>

int main() {
    // create context, module and builder
    LLVMContextRef context = LLVMContextCreate();
    LLVMModuleRef  module = LLVMModuleCreateWithNameInContext("hello", context);
    LLVMBuilderRef builder = LLVMCreateBuilderInContext(context);

    // types
    LLVMTypeRef int_8_type = LLVMInt8TypeInContext(context);
    LLVMTypeRef int_8_type_ptr = LLVMPointerType(int_8_type, 0);
    LLVMTypeRef int_32_type = LLVMInt32TypeInContext(context);

    // puts function
    LLVMTypeRef puts_function_args_type[] {
        int_8_type_ptr
    };

    LLVMTypeRef  puts_function_type = LLVMFunctionType(int_32_type, puts_function_args_type, 1, false);
    LLVMValueRef puts_function = LLVMAddFunction(module, "puts", puts_function_type);
    // end

    // main function
    LLVMTypeRef  main_function_type = LLVMFunctionType(int_32_type, nullptr, 0, false);
    LLVMValueRef main_function = LLVMAddFunction(module, "main", main_function_type);

    LLVMBasicBlockRef entry = LLVMAppendBasicBlockInContext(context, main_function, "entry");
    LLVMPositionBuilderAtEnd(builder, entry);

    LLVMValueRef puts_function_args[] = {
        LLVMBuildPointerCast(builder, // cast [14 x i8] type to int8 pointer
                LLVMBuildGlobalString(builder, "Hello, World!", "hello"), // build hello string constant
                int_8_type_ptr, "0")
    };

    LLVMBuildCall2(builder, puts_function_type, puts_function, puts_function_args, 1, "i");
    LLVMBuildRet(builder, LLVMConstInt(int_32_type, 0, false));
    // end

    //LLVMDumpModule(module); // dump module to STDOUT
    LLVMPrintModuleToFile(module, "hello.ll", nullptr);

    // clean memory
    LLVMDisposeBuilder(builder);
    LLVMDisposeModule(module);
    LLVMContextDispose(context);

    return 0;
}