[lworld] Integrated: 8370714: [lworld] Reimplement System.identityHashCode for Value Objects

[Roger Riggs]

On Fri, 5 Dec 2025 21:24:41 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

> The alternate hashcode compution is enabled when the alternate subsitutability method is enabled with: `-XX:+UseAltSubstitutabilityMethod`. 
> The IdentityHashCode is computed using the map of field offsets and sizes from Unsafe. 
> The basis of hashCode is the the hashCode of the object's class mixing in the values from the memory where the fields are placed and the hashCode of each reference.
> 
> The changes to Hotspot invoke the original or the alternate Java method based on the VM `UseAltSubstitutabilityMethod` command line flag.

This pull request has now been integrated.

Changeset: 9f73e019
Author:    Roger Riggs <rriggs at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/9f73e0195931e6840b8cbc442f0a6c0e81bbe8a2
Stats:     85 lines in 7 files changed: 71 ins; 0 del; 14 mod

8370714: [lworld] Reimplement System.identityHashCode for Value Objects

Reviewed-by: liach, fparain

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PR: https://git.openjdk.org/valhalla/pull/1773