On Fri, 21 Feb 2025 00:01:36 GMT, Chen Liang <li...@openjdk.org> wrote:
> Simplify the layout access var handles to be direct in some common cases. > Also made `VarHandle::isAccessModeSupported` report if an access mode is > supported for a VH. > > Reduces the instructions to execute this code in a simple main by 47%: > > long[] arr = new long[8]; > var ms = MemorySegment.ofArray(arr); > ms.setAtIndex(ValueLayout.JAVA_BYTE, 12, (byte) 3); > > > Main overheads in FFM are identified to be: > 1. Eager initialization of direct MethodHandle; can be CDS archived > 2. MH combinator forms via LambdaFormEditor, not cached right now and always > have large overhead > > Still need other measures to deal with common user patterns of > `MethodHandles.insertCoordinates(vh, 1, 0L)` which currently is still very > slow. > > Tests: 2 unrelated failures on tier 1-3 This pull request has now been integrated. Changeset: c7fa499b Author: Chen Liang <li...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/c7fa499bf5023a3f16bb3742d2ba3cd74f2b41bd Stats: 1720 lines in 18 files changed: 1046 ins; 209 del; 465 mod 8350118: Simplify the layout access VarHandle Reviewed-by: mcimadamore, jvernee, erikj ------------- PR: https://git.openjdk.org/jdk/pull/23720
