Integrated: 8364235: Fix for JDK-8361447 breaks the alignment requirements for GuardedMemory

[David Holmes]

On Tue, 29 Jul 2025 06:32:20 GMT, David Holmes <dholmes at openjdk.org> wrote:

> The fix for [JDK-8361447](https://bugs.openjdk.org/browse/JDK-8361447) added a new field to the `GuardHeader`, not realizing that the size of the `GuardHeader` must be such that the address of the user-data has the strictest necessary alignment (16-byte).
> 
> We need to add a padding field to restore the alignment.
> 
> A static assert is added to check the alignment.
> 
> Testing:
>  - tiers 1-3 (in progress)
> 
> Thanks

This pull request has now been integrated.

Changeset: 078d0d49
Author:    David Holmes <dholmes at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/078d0d4968e26bb7a15417f1c4e891869c69dc6c
Stats:     14 lines in 1 file changed: 8 ins; 2 del; 4 mod

8364235: Fix for JDK-8361447 breaks the alignment requirements for GuardedMemory

Co-authored-by: Johan Sjölen <jsjolen at openjdk.org>
Reviewed-by: dcubed, jsjolen, aboldtch

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PR: https://git.openjdk.org/jdk/pull/26524