Re: RFR: 8390049: Zero-copy vector alternative to a scalar loop over charAt

[ExE Boss]

On Fri, 14 Aug 2026 11:04:41 GMT, Liam Miller-Cushon <cus...@openjdk.org> wrote:

> See
> 
> * [panama-dev@ thread 'String processing and Vector 
> APIs'](https://mail.openjdk.org/archives/list/panama-...@openjdk.org/thread/YSPX3TBXZTZEFZNXWDYOZCWLUQPC62P6/)
> * [JDK-8390049: Immutable zero-copy String views of a String's code 
> units](https://bugs.openjdk.org/browse/JDK-8390049)
> 
> 
> 
> 
> ---------
> - [x] I confirm that I make this contribution in accordance with the [OpenJDK 
> Interim AI Policy](https://openjdk.org/legal/ai).

src/java.base/share/classes/java/lang/System.java line 2229:

> 2227:             public MemorySegment asReadOnlyMemorySegment(String str) {
> 2228:                 return MemorySegment.ofArray(str.value()).asReadOnly();
> 2229:             }

Note that it’s generally preferred for `*Access` methods to keep their 
implementations trivial, that is, do:
Suggestion:

            public MemorySegment asReadOnlyMemorySegment(String str) {
                return str.asReadOnlyMemorySegment();
            }

And add the following method to `java.lang.String`:

/* package-private */ MemorySegment asReadOnlyMemorySegment() {
        return MemorySegment.ofArray(this.value).asReadOnly();
}

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

PR Review Comment: https://git.openjdk.org/jdk/pull/32373#discussion_r3984542191