[lworld] Integrated: 8373787: [lworld] InstanceKlass::size mixes bytes and words

[Stefan Karlsson]

On Tue, 16 Dec 2025 12:26:42 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> The following function in `InstanceKlass` is supposed to return size in words:
> 
>   static int size(int vtable_length, int itable_length,
>                   int nonstatic_oop_map_size,
>                   bool is_interface,
>                   bool is_inline_type) {
>     return align_metadata_size(header_size() +
>            vtable_length +
>            itable_length +
>            nonstatic_oop_map_size +
>            (is_interface ? (int)sizeof(Klass*)/wordSize : 0) +
>            (is_inline_type ? (int)sizeof(InlineKlassFixedBlock) : 0));
>   }
> 
> but `sizeof(InlineKlassFixedBlock)` returns a size in bytes. This adds 640 bytes instead of 80 bytes to all InlineKlasses.
> 
> This can be seen by running `jcmd <pid> VM.classes` to check the size of the InlineKlass of Integer before and after the fix for this:
> 
> Before:
> 
> 0x00000ffc0024d260 167 fully_initialized WS java.lang.Integer
> 
> After:
> 
> 0x000001800024d260 97 fully_initialized WS java.lang.Integer
> 
> 
> That is in words. So this bug added an extra `(167 - 97) * 8 == 560` bytes. 
> 
> I've so far only done some local smoke testing with TEST=hotspot_valhalla

This pull request has now been integrated.

Changeset: e82573ea
Author:    Stefan Karlsson <stefank at openjdk.org>
Committer: Paul Hübner <phubner at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/e82573ea7cc59d92aa57f17674e4e52ffd619751
Stats:     4 lines in 2 files changed: 0 ins; 0 del; 4 mod

8373787: [lworld] InstanceKlass::size mixes bytes and words

Reviewed-by: phubner, fparain

-------------

PR: https://git.openjdk.org/valhalla/pull/1804