On Fri, 13 Feb 2026 15:01:59 GMT, Paul Hübner <[email protected]> wrote:
>> Leonid Mesnik has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> fixed gp name
>
> test/hotspot/jtreg/vmTestbase/nsk/share/gc/Memory.java line 139:
>
>> 137: return getReferenceSize();
>> 138: }
>> 139: return 8;
>
> This comment applies to all `getXXXArrayElementSize` methods. The element
> size depends on many things, such as the properties of the array (controls
> flattening decisions and/or layout) and the VM (flattening can be disabled).
>
> For JEP 401, we only consider the nullable atomic layout. Even for this
> simple case, we should, in my opinion, do the following:
> - Check if flattening is enabled. For this, we can use the `WhiteBox` API to
> get the VM flag values. Some relevant flags may be: `UseArrayFlattening`,
> `UseFieldFlattening`, `UseNullableValueFlattening`,
> `UseAtomicValueFlattening`.
> - File an RFE to track hardcoding the size, such that we can change it once
> there are more layouts available.
>
> A more robust solution would be to use
> `test/hotspot/jtreg/runtime/valhalla/inlinetypes/field_layout/FieldLayoutAnalyzer.java`
> in order to get more comprehensive layout information.
Thanks for pointer. It is very good example.
But as I said, we need to find single solution for Memory sizes. And more
important is it worth for these tests or such "rough" estimation is enough.
> test/hotspot/jtreg/vmTestbase/nsk/share/gc/Memory.java line 208:
>
>> 206: int length = (int) Math.min((memory - arrayExtraSize) /
>> objectSize,
>> 207: Integer.MAX_VALUE);
>> 208: return Math.max(length, 0);
>
> In which scenarios do you anticipate to get a negative `length`?
When we create a lot of small arrays, it finally might be got something like
getArrayLength(memory = 8 , objectSize)
so
memory - arrayExtraSize
become negative.
> test/hotspot/jtreg/vmTestbase/nsk/share/gc/MemoryObject.java line 49:
>
>> 47: }
>> 48: } else {
>> 49: storage = new int[0];
>
> This else case wasn't here before right? I'm not sure I follow why we need an
> empty array.
just to always have initialized not-null:
`private final Object storage;`
-------------
PR Review Comment:
https://git.openjdk.org/valhalla/pull/2099#discussion_r2804924130
PR Review Comment:
https://git.openjdk.org/valhalla/pull/2099#discussion_r2804918932
PR Review Comment:
https://git.openjdk.org/valhalla/pull/2099#discussion_r2804922280
