How do I use -fno-exceptions and -fno-rtti trade-offs?

In C++, two important compiler options can significantly affect the performance and behavior of your application: -fno-exceptions and -fno-rtti. Understanding their trade-offs is essential for optimizing your C++ program.

Using -fno-exceptions

By default, C++ supports exception handling, allowing you to catch and deal with errors at runtime. However, using -fno-exceptions disables this feature, which can lead to a smaller binary size and potentially faster execution. This is especially useful in systems where low latency is critical, such as embedded systems or real-time applications.

Using -fno-rtti

Runtime type identification (RTTI) allows the type of an object to be determined during program execution. Disabling RTTI with -fno-rtti can further optimize your application by reducing the overhead associated with type information. This is particularly beneficial in performance-critical applications where you control type safety manually (for instance, through careful use of templates or inheritance).

Trade-offs

• Pros: Reduced binary size and potentially improved performance.
• Cons: Loss of exception safety and dynamic type information can lead to more complex error handling and debugging processes.

Example Usage

// Example of a simple C++ program without exceptions and RTTI
#include 

class Base {
public:
    virtual void show() { std::cout << "Base class" << std::endl; }
};

class Derived : public Base {
public:
    void show() override { std::cout << "Derived class" << std::endl; }
};

int main() {
    Base* b = new Base();
    b->show(); // Works fine: prints "Base class"
    // Without RTTI, we cannot safely cast, and without exceptions, we can't catch errors.
    return 0;
}