Regarding the latest JEP 401 update

[Remi Forax]

> From: "-" <liangchenblue at gmail.com>
> To: "valhalla-dev" <valhalla-dev at openjdk.org>
> Sent: Saturday, September 23, 2023 4:27:24 AM
> Subject: Regarding the latest JEP 401 update

> Hello,

Hello, 

> First thanks to the expert group and Dan for an update to JEP 401! The updated
> version looks very straightforward and actionable.

> I have a few comments in mind:
> 1. Why are method descriptor's types preloaded? They are not part of the object
> layout.

They are part of the method calling convention. We want to try to avoid boxing when calling methods that take a value type as parameter. 
For that we need to know if a parameter type/return type is a value type or not. 
This is especailly important for virtual methods (methods that can be called through a vtable) because the vtable/itable are populated early, at least in the case of Hotspot, other VMs may differ. 

> 2. API support should mention java.lang.reflect.AccessFlag.
> 3. More value classes aside from Optional can be migrated: OptionalInt,
> OptionalDouble, OptionalLong.

> Best,
> Chen Liang

regards, 
Rémi 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/valhalla-dev/attachments/20230923/97160ffb/attachment.htm>