RFR: 8338677: Improve startup of memory access var handles by simplifying combinator chains

[Chen Liang]

On Tue, 20 Aug 2024 21:13:29 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> src/java.base/share/classes/jdk/internal/foreign/Utils.java line 245:
>> 
>>> 243: 
>>> 244:     @ForceInline
>>> 245:     public static void checkEnclosingLayout(MemorySegment segment, long offset, MemoryLayout enclosing, boolean readOnly) {
>> 
>> Can't the first argument be `AbstractMemorySegmentImpl`? The new call site already has an `AbstractMemorySegmentImpl` and the private static method site can do the cast instead.
>
> I suppose it could yes - any reason as to why moving the cast around is better?

Just stylistic - you cast `segment` to `AbstractMemorySegmentImpl` twice here, and if you count here https://github.com/openjdk/jdk/pull/20647/files#diff-e483572155b915ded5f6290c0e91fcf3feeaadf117865ea744920b9b9bbbec45R103 you have already casted 3 times in var handles. You can change the type here and add one new cast here: https://github.com/openjdk/jdk/pull/20647/files#diff-8b4feba9593ad63edaad23970fff28004f916bfa2bf45970f63fad83fb46cd92R289

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PR Review Comment: https://git.openjdk.org/jdk/pull/20647#discussion_r1724002020