From daniel.smith at oracle.com  Mon Jan  5 23:21:56 2026
From: daniel.smith at oracle.com (Dan Smith)
Date: Mon, 5 Jan 2026 23:21:56 +0000
Subject: Porting to support JEP 401: Value Classes and Objects (Preview)
Message-ID: <085DD22C-C0D6-4E47-94E2-533AE72381AB@oracle.com>

Hello, porters! The Valhalla project has been implementing JEP 401: Value Classes and Objects (Preview) in a branch of our Github repository. Over the next few months, we will be preparing to target and integrate the JEP.

This will be a very large commit touching many components of HotSpot, so now is a good time to start aligning your ports with the anticipated changes and ensuring conformance with the updated specifications.

Some pointers:

Value Classes JEP: https://openjdk.org/jeps/401
Supplementary strict field initialization JEP: https://openjdk.org/jeps/8350458

JVMS changes (value classes): https://cr.openjdk.org/~dlsmith/jep401/jep401-20251210/specs/value-objects-jvms.html
JVMS changes (field initialization): https://cr.openjdk.org/~dlsmith/jep401/jep401-20251210/specs/strict-fields-jvms.html

Git branch: https://github.com/openjdk/valhalla/tree/lworld

As a baseline, you may want to focus on *compliance* without adopting any of the value object *optimizations*. A compliant JVM will recognize and validate the ACC_IDENTITY and ACC_STRICT_INIT flags, and will follow the new semantics for 'acmp', 'ifnull', and 'monitorenter'; but can ignore the contents of 'LoadableDescriptors', and need not support scalarized or flattened object encodings.

Please reach out to valhalla-dev, or to me personally, if you need any help or clarifications to align with these changes.

From martin.doerr at sap.com  Thu Jan  8 22:24:31 2026
From: martin.doerr at sap.com (Doerr, Martin)
Date: Thu, 8 Jan 2026 22:24:31 +0000
Subject: Porting to support JEP 401: Value Classes and Objects (Preview)
In-Reply-To: <085DD22C-C0D6-4E47-94E2-533AE72381AB@oracle.com>
References: <085DD22C-C0D6-4E47-94E2-533AE72381AB@oracle.com>
Message-ID: <AS8PR02MB8544FD856E4859BC97C879439A85A@AS8PR02MB8544.eurprd02.prod.outlook.com>

Hi Dan,

Thanks for the heads-up! We will look into it and plan a PPC64 port.

Best regards,
Martin

Von: porters-dev <porters-dev-retn at openjdk.org> im Auftrag von Dan Smith <daniel.smith at oracle.com>
Datum: Dienstag, 6. Januar 2026 um 00:22
An: porters-dev at openjdk.org <porters-dev at openjdk.org>
Betreff: Porting to support JEP 401: Value Classes and Objects (Preview)

Hello, porters! The Valhalla project has been implementing JEP 401: Value Classes and Objects (Preview) in a branch of our Github repository. Over the next few months, we will be preparing to target and integrate the JEP.

This will be a very large commit touching many components of HotSpot, so now is a good time to start aligning your ports with the anticipated changes and ensuring conformance with the updated specifications.

Some pointers:

Value Classes JEP: https://openjdk.org/jeps/401
Supplementary strict field initialization JEP: https://openjdk.org/jeps/8350458

JVMS changes (value classes): https://cr.openjdk.org/~dlsmith/jep401/jep401-20251210/specs/value-objects-jvms.html
JVMS changes (field initialization): https://cr.openjdk.org/~dlsmith/jep401/jep401-20251210/specs/strict-fields-jvms.html

Git branch: https://github.com/openjdk/valhalla/tree/lworld

As a baseline, you may want to focus on *compliance* without adopting any of the value object *optimizations*. A compliant JVM will recognize and validate the ACC_IDENTITY and ACC_STRICT_INIT flags, and will follow the new semantics for 'acmp', 'ifnull', and 'monitorenter'; but can ignore the contents of 'LoadableDescriptors', and need not support scalarized or flattened object encodings.

Please reach out to valhalla-dev, or to me personally, if you need any help or clarifications to align with these changes.
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