[lworld] Integrated: 8376221: [lworld] Do not store array of InlineLayoutInfo for all InstanceKlasses

[Joel Sikström]

On Mon, 26 Jan 2026 08:43:40 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

> Hello,
> 
> Please refer to the JBS issue for a more detailed description of the background of this change. In summary, I suggest we only keep the array of InlineLayoutInfo for InstanceKlasses which need it, which are Klasses that have fields that have been inlined.
> 
> To make the transition to this easier, I suggest we change the following properties in FieldLayoutBuilder: 
> 
> _has_inline_type_fields
> _has_flattening_information
> 
> to
> 
> _has_inlineable_fields
> _has_inlined_fields
> 
> The `_has_inlineable_fields` property is only used for printing and `_has_inlined_fields` is the property we expose out to the ClassFileParser, telling us that this class has inlined fields, so the array of InlineLayoutInfo must be "preserved" and is possible to read from. Hence, the array is now only safe to access if `InstanceKlass::has_inlined_fields` is true, or simply if the actual field being accessed is flat (`fieldDescriptor::is_flat`).
> 
> I only found one place (in ciReplay.cpp) where we access the array of InlineLayoutInfo even though we might not have any inlined fields and only fields that are inlineable. I've changed this to use the normal "reference" path for fields that aren't flat.
> 
> Testing:
> * Oracle's tier1-5, hotspot_valhalla and jdk_valhalla

This pull request has now been integrated.

Changeset: 53c55318
Author:    Joel Sikström <jsikstro at openjdk.org>
Committer: Paul Hübner <phubner at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/53c55318228dabef79be8939f50a3d686f752b3b
Stats:     156 lines in 11 files changed: 75 ins; 28 del; 53 mod

8376221: [lworld] Do not store array of InlineLayoutInfo for all InstanceKlasses

Reviewed-by: phubner, fparain

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PR: https://git.openjdk.org/valhalla/pull/1966