Issue #113: Grow the code for relocatables, and do fixup, and relocate

[HeartSaVioR]

There's a bug discovered in #113 which padding is applied multiple times due to growing in relocatable. Once there's any relocatable growing the code, padding is re-applied without rolling back padding previously added. In some circumstance, applying multiple padding adds more bytes than padding between TABLESWITCH OP code and default parameter, and breaks bytecode.

Looking into codebase, I found the following:

• Growing only happens in Branch
• Once it adds spaces, expanded is marked as true, and no grow will be happen

Based on this logic, we may be able to simplify the logic of fixUpAndRelocate to sequential steps, grow code -> do fixUp -> relocate.

This patch adds new UT to reproduce #113 - it fails on latest master branch, and passes with this PR.

[HeartSaVioR]

I'm not familiar with Janino hence I had to put lots of assumptions while fixing the code.

    /**
     * Fixes up all of the offsets and relocate() all relocatables.
     */
    public void
    fixUpAndRelocate() {


        // We do this in a loop to allow relocatables to adjust the size
        // of things in the byte stream.  It is extremely unlikely, but possible
        // that a late relocatable will grow the size of the bytecode, and require
        // an earlier relocatable to switch from 32K mode to 64K mode branching
        do {
            this.fixUp();
        } while (!this.relocate());
    }

Is there any chance for the PR breaking the comment? I'm not 100% sure but there might be the case if fixUp adds space between source and destination of relocatable which wasn't wide but becomes wide. I guess it should be extremely unlikely even if it's valid, but if this is a valid case, it's going to be complicated - padding should be corrected via new offset after growing.

[aunkrig]

Hey Lim,

this is brilliant work!! The test case reproduces the problem, the fix works, and the program structure is even cleaner now. Congrats!! If all bug reports were so easy to process...

I merged your proposed changes exactly as they were.

CU Arno

[HeartSaVioR]

Thanks for reviewing and merging!