deduplicating lambda methods

[Liam Miller-Cushon]

On Tue, Mar 27, 2018 at 11:43 AM Vicente Romero <vicente.romero at oracle.com>
wrote:

> >>> I believe --debug options are used to generate extra information out of
> >>> javac, not to alter its behavior - it's probably better to use an
> hidden
> >>> flag (e.g. -XDdeduplicateLambdas=...) - which is consistent to what we
> have
> >>> done for indy string concat.
> >>>
> >> I will introduce this change before pushing the patch,
> > Should this option really be hidden? It's currently necessary to
> > disable de-duplication when debugging to preserve all LNT/LVT.
> > Of course, this could be a '-X...' instead of '-g' but documented, I
> think.
> > Note that de-duplication doesn't really alter javac behavior; let say
> > 'in reverse' that lambda *duplication* would be an additional debug
> > information...
>
> err, I think you have a good point. I have already pushed the patch to:
> http://hg.openjdk.java.net/jdk/jdk, but we can still rework the option
>

To make sure we're all on the same page, the feature is unconditionally
disabled if -g or -g:{lines,vars} is passed, to ensure the LNT/LVT info is
correct. The feature can also be disabled with -XDdeduplicateLambdas,
but it isn't necessary to explicitly set that flag to preserve LNT/LVT info.

The logic for this is here:
http://hg.openjdk.java.net/jdk/jdk/rev/752ecccb0b7f#l1.116