CODEWITHSUNDEEP
compiler-construction
齐天大圣
齐天大圣

Reputation: 1189

Compiler: code generation for lvalue and rvalue

I am writing a small compiler for a java-like language, except that every thing is object in this language, even the primitive type.

Consider the following code:

class Main inherits IO {

    fib(x : Int) : Int {
        if x < 2
        then x
        else fib(x - 1) + fib(x - 2)
        fi
    };

    main() : Object {
        out_int(fib(10))
    };
};

In my implementation, everything that pass into a function is a copy of the reference to that object. (so 10 is an integer object). So the fib function will also return an integer object.

However, fib(x - 1) + fib(x - 2) requires two function's results to be rvalue, so it can properly perform addition.

I couldn't come up with a automatic way to handle this problem: how to find a way so that the compiler knows when to generate code for a lvalue and when for a rvalue?

Upvotes: 1

Views: 104

Answers (1)

Johan
Johan

Reputation: 3891

I think that you can just ignore the difference. Consider + as a function that takes two references to integer objects a,b and returns the reference to a new object whose value is the sum of a and b. This function must, of course, be implemented by the compiler but apart from that it should be similar to other functions.

Upvotes: 1

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