On Mon, 20 May 2024 16:42:19 GMT, Paul Sandoz <psan...@openjdk.org> wrote:
> some additional overhead e.g.,
>
> ```
> if (derefAdapters.length == 0) {
> // insert align check for the root layout on the initial MS +
> offset
> List<Class<?>> coordinateTypes = handle.coordinateTypes();
> MethodHandle alignCheck =
> MethodHandles.insertArguments(MH_CHECK_ENCL_LAYOUT, 2, rootLayout());
> handle = MethodHandles.collectCoordinates(handle, 0, alignCheck);
> int[] reorder = IntStream.concat(IntStream.of(0, 1),
> IntStream.range(0, coordinateTypes.size())).toArray();
> handle = MethodHandles.permuteCoordinates(handle,
> coordinateTypes, reorder);
> }
> ```
True, the chain for segment var handle is quite long (and that is not a result
of this patch, it has always been more or less like that). Funnily, I was
staring at this piece of code the other day, and I think this can be dealt with
morally with a `foldArguments`, but we don't have the equivalent of that in the
VH/coordinates world. Maybe we should add that (or at least implement
internally) as that would simplify the adaptation, avoiding the permute step
(which is typically rather heavy).
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PR Comment: https://git.openjdk.org/jdk/pull/19251#issuecomment-2120979087
