[lworld] RFR: 8228361: [lworld] Optimize the substitutability check in C2 [v3]

[Tobias Hartmann]

On Thu, 18 Dec 2025 15:52:23 GMT, Manuel Hässig <mhaessig at openjdk.org> wrote:

>> Not sure if I'm following, do you mean by inverting the condition of `if (this_field->is_InlineType()) {`?
>
> I meant
> ```c++
> if (ft->is_primitive_type()) {
>   acmp_val_guard();
> } else if (this_type->is_InlineType()) {
>   ...
> } else {
>   assert()
> }
> 
> But now that I wrote it down, I fail to see the benefit.

I don't think that would be equivalent / correct though because we need to take that path as well when `!ft->is_primitive_type()`, right? The field can be of an object type that is `!ft->as_klass()->can_be_inline_klass()`.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1823#discussion_r2631668585