deduplicating lambda methods

[Liam Miller-Cushon]

I uploaded a webrev with the current sketch:
http://cr.openjdk.java.net/~cushon/lambdadedup/webrev.00/webrev/

* Nothing here is intended to be final, I'm interested in feedback on the
direction and any suggestions for next steps.
* It shows the approach used for ast comparison, including the lambda
parameter handling I described. The lambda parameter handling is currently
baked-in, but it could easily be refactored to allow the ast diffing to be
used in other contexts.
* There is no handling of debug info yet.

On Sun, Mar 4, 2018 at 7:59 PM Liam Miller-Cushon <cushon at google.com> wrote:

> On Fri, Mar 2, 2018 at 8:01 PM, Vicente Romero <vicente.romero at oracle.com>
> wrote:
>
>> 1) How to identifying duplicates: I have a prototype that runs during
>>> lambda desugaring and identifies duplicates by diffing ASTs. Is that the
>>> best place for deduplication, or it worth considering comparing generated
>>> code instead of ASTs?
>>>
>>
>> are you doing an exact diff? I assume that we want: s -> s to be equal to
>> z -> z provided that the target is the same
>
>
> Lambda parameters are currently handled as a special case. The diff tests
> that the syntax for the two trees is the same, and that the symbols
> associated with identifier and select nodes are equivalent. It accepts
> symbols that correspond to the same parameter in each of the associated
> lambda methods.
>
> E.g. when diffing the lambda bodies for `s -> s` and `x -> x` it sees that
> `s` and `x` are both the first parameter of their enclosing lambdas.
>