RFR: 8350118: Simplify the layout access VarHandle

[Maurizio Cimadamore]

On Fri, 21 Feb 2025 16:04:57 GMT, Chen Liang <liach at openjdk.org> wrote:

>> src/java.base/share/classes/java/lang/invoke/X-VarHandleSegmentView.java.template line 77:
>> 
>>> 75:         }
>>> 76: 
>>> 77:         @ForceInline
>> 
>> Question: can this and the `offset` method go in the `VarHandleSegmentViewBase` class? They don't seem to depend on anything in these classes - so it seems mostly duplicated code?
>
> Now this will require code update to static import `offset` from `VarHandleSegmentViewBase`. Is that acceptable?

Maybe let's leave it, at least in this round

>> src/java.base/share/classes/jdk/internal/foreign/layout/ValueLayouts.java line 164:
>> 
>>> 162:         @ForceInline
>>> 163:         public final VarHandle varHandle() {
>>> 164:             record VarHandleCache() implements Function<AbstractValueLayout<?>, VarHandle> {
>> 
>> Can this cache be removed? The var handles created here should be "direct" -- meaning that we don't expect LayoutPath to add any adaptations on top of what's already done in the "raw" var handle returned by `Utils:makeRawSegmentViewVarHandle`?
>
> We have two caches, one in `ValueLayouts` and another in `Utils`. Should we remove both?

I'm not convinced about the one in ValueLayouts *e.g. where this comment was added) -- if you agree that the other cache should already handle this -- then maybe we can only keep one

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

PR Review Comment: https://git.openjdk.org/jdk/pull/23720#discussion_r1966002718
PR Review Comment: https://git.openjdk.org/jdk/pull/23720#discussion_r1965999335