RFR: 8367129: Move input validation checks to Java for java.lang.StringLatin1 intrinsics

[Damon Fenacci]

On Mon, 15 Dec 2025 20:30:51 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

> Moves input validation checks to Java for `java.lang.StringLatin1` intrinsics. While doing so, affected `java.lang.StringUTF16` methods needed to be updated due to relaxed checks at intrinsics. The javadocs of the touched methods are extensively overhauled.

Thanks for looking into this @vy! I left a couple of comments/questions (I've mostly checked the intrinsic part).

src/hotspot/share/classfile/vmIntrinsics.hpp line 402:

> 400:    do_signature(indexOfChar_signature,                           "([BIII)I")                                            \
> 401:   do_intrinsic(_equalsL,                  java_lang_StringLatin1,equalsS_name, equalsB_signature,                 F_S)  \
> 402:     do_name(    equalsS_name,                                    "equals0")                                             \

Suggestion:

   do_name(    equalsS_name,                                     "equals0")                                             \

src/java.base/share/classes/java/lang/StringLatin1.java line 2:

> 1: /*
> 2:  * Copyright (c) 2015, 2025, Oracle and/or its affiliates. All rights reserved.

Suggestion:

 * Copyright (c) 2015, 2026, Oracle and/or its affiliates. All rights reserved.

src/java.base/share/classes/java/lang/StringLatin1.java line 172:

> 170:         Objects.requireNonNull(other);
> 171:         String.checkOffset(len1, length(value));
> 172:         String.checkOffset(len2, length(other));

Are these additional checks? I'm asking because I was expecting them to "replace" intrinsics ones but couldn't find where/how (if so I'm also wondering why they were not there before: did all callers ensure that?).

src/java.base/share/classes/java/lang/StringLatin1.java line 220:

> 218:     static int compareToUTF16(byte[] value, byte[] other, int len1, int len2) {
> 219:         Objects.requireNonNull(value);
> 220:         Objects.requireNonNull(other);

[Similar question](https://github.com/openjdk/jdk/pull/28832/changes#r2788781455)

src/java.base/share/classes/java/lang/StringLatin1.java line 266:

> 264:     static int compareToCI_UTF16(byte[] value, byte[] other) {
> 265:         Objects.requireNonNull(value);
> 266:         Objects.requireNonNull(other);

[Similar question](https://github.com/openjdk/jdk/pull/28832/changes#r2788781455)

src/java.base/share/classes/java/lang/StringUTF16.java line 2:

> 1: /*
> 2:  * Copyright (c) 2015, 2025, Oracle and/or its affiliates. All rights reserved.

Suggestion:

 * Copyright (c) 2015, 2026, Oracle and/or its affiliates. All rights reserved.

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

PR Review: https://git.openjdk.org/jdk/pull/28832#pullrequestreview-3777437085
PR Review Comment: https://git.openjdk.org/jdk/pull/28832#discussion_r2786516405
PR Review Comment: https://git.openjdk.org/jdk/pull/28832#discussion_r2786502065
PR Review Comment: https://git.openjdk.org/jdk/pull/28832#discussion_r2788781455
PR Review Comment: https://git.openjdk.org/jdk/pull/28832#discussion_r2788831821
PR Review Comment: https://git.openjdk.org/jdk/pull/28832#discussion_r2788869295
PR Review Comment: https://git.openjdk.org/jdk/pull/28832#discussion_r2786504049