Deadcode elimination optimizatio pass breaking (invalid jump position: 0)

[Ricardo Catalinas Jiménez]

Hi, first of all thanks for such a great project! We wanted to report a recent issue we found.

When using return statements that don't return any value, we got the next error from the compiler:

panic: invalid jump position: 0

This triggers usually when there are multiple exit points in the function (returns), and also there are conditional jumps (IFs or FORs loops with return statements). This is a small example that triggers the bug:

fmt := import("fmt")

fmt.println("Hello")

f := func(a, b) {
    if a > 0 {
        return
    }

    // This standalone return statement causes the deadcode optimization pass to break,
    // if you remove it, everything works as expected.
    return

    return 123
}

r := f(0, 2)

fmt.println("Bye")
fmt.println(r)
fmt.println(is_undefined(r))

I think the issue must be or in the optimization pass or even before on how the bytecode for the standalone return statement is generated. At the moment I didn't have time to investigate further, but simply disabling for the time being the deadcode elimination solves the problem for us as a stopgap solution.

Let us know if you need more details or how we can help. Will post here if I discover more details.

We are running with version: v2.10.0 (4846cf5)

[E Sequeira]

Thanks for reporting the bug. I have a fix for this in PR now