Re: Binary Compatibility

[Bryce McKinlay <bryce at mckinlay dot net dot nz>]

On Thursday, Jul 31, 2003, at 03:57 Pacific/Auckland, Andrew Haley 
wrote:

> I want to start work on the Binary Compatibility project.
>
> I know that -findirect-dispatch is in the compiler, but I don't know
> how well it works in practice.

It works pretty good as far as it goes (virtual methods), and I think 
it provides a good base for doing the rest of the binary compatibility 
work. One thing it does do differently to the Dachuan et al paper is to 
share the offset tables between classes in a compilation unit. If we 
want to strictly adhere to the JLS with regards to access checking - ie 
handling the case of a formerly public method changing to protected, 
etc, then the runtime needs to know which class each entry belongs to, 
so a separate offset table for each class would be required. That would 
be easy to implement, but at the cost of increased table size and thus 
potentially reduced performance.

Regards

Bryce.