RFR: 8372948: Store end positions directly in JCTree

[Liam Miller-Cushon]

On Tue, 2 Dec 2025 16:21:21 GMT, Jonathan Gibbons <jjg3 at pobox.com> wrote:

> Without looking in detail at this specific proposal, I wonder if you considered the alternative to only store end positions in the subtypes of JCTree that actually "need" them. In other words, you only need store end positions in tree nodes that "end" in a lexical token and not in a child tree node. Effectively, you only need store the end position in tree nodes that would otherwise have entries in the EndPosTable.

Good question--I hadn't investigated that option. It seems do-able, perhaps with a shared interface for subtypes that needed end positions to simplify the handling of them.

What tradeoffs do you see here, would only declaring the field on trees that need it be mostly about saving memory?

Also is that unique to end positions? Or could javac potentially avoid storing start positions for nodes that don't start with a lexical token as well?

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PR Comment: https://git.openjdk.org/jdk/pull/28610#issuecomment-3602921946