RFR: 8342967: Lambda deduplication fails with non-metafactory BSMs and mismatched local variables names [v2]

[Maurizio Cimadamore]

On Thu, 24 Oct 2024 22:14:40 GMT, Aggelos Biboudis <abimpoudis at openjdk.org> wrote:

>> After experimentation and under certain conditions, a few equivalent lambdas (up to variable renaming) fail to deduplicate.
>> 
>> `TreeHasher` and `TreeDiffer` are now aware that other bootstraps may appear in lambda bodies (e.g. `SwitchBootstraps.typeSwitch`) and that variable names do not matter (when they appear in method/lambda definitions). In the first case equivalence is checked based on `bsmKey` and not the `Dynamic{Var, Method}Symbol` itself.
>> 
>> The test was also adjusted since it was assuming BSM with certain structure only (that `.get(1)` was unprotected).
>
> Aggelos Biboudis has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address review

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeDiffer.java line 207:

> 205:     }
> 206: 
> 207:     private boolean scan(Symbol symbol, Symbol otherSymbol) {

Consider renaming this to `scanSymbol`, to make it clear it doesn't apply to trees.

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeDiffer.java line 224:

> 222:         Symbol otherSymbol = that.sym;
> 223: 
> 224:         if (result)

This could also be:


result = scan(tree.selected, that.selected) &&
                   scan(tree.sym, that.sym);


Right?

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/21687#discussion_r1816513551
PR Review Comment: https://git.openjdk.org/jdk/pull/21687#discussion_r1816513042