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 I wonder if the changes affecting `isAccessModeSupported` should warrant a small CSR? ------------- PR Comment: https://git.openjdk.org/jdk/pull/23720#issuecomment-2674266390
