JVMS changes for JEP 401

[Remi Forax]

Hello,
in section 6.5, the specified behavior of acmp_eq/acmp_ne for fields of type float and double has been changed.

The last time we discussed that subject, the idea was to align the semantics of a field of type float (double) to the semantics of Float.equals() (Double.equals()), but now the spec has been changed to compare the bitwise representations.

What is the underlying reason for that change ?

Rémi

----- Original Message -----
> From: "daniel smith" <daniel.smith at oracle.com>
> To: "valhalla-spec-experts" <valhalla-spec-experts at openjdk.java.net>
> Sent: Wednesday, January 24, 2024 2:11:18 AM
> Subject: JVMS changes for JEP 401

> I've posted a revised spec change document for JEP 401, Value Classes and
> Objects, here:
> 
> https://cr.openjdk.org/~dlsmith/jep401/jep401-20240116/specs/value-objects-jvms.html
> 
> Not covered by JVMS is anything to do with our internal-only null restriction
> annotations, or (naturally) anything about scalarization/flattening. Of course
> those things represent a large chunk of the code changes that we anticipate
> delivering with JEP 401.
> 
> We've already identified a few issues from internal reviews, which I'll address
> in a followup iteration:
> 
> - 5.3.5 needs to allow JVM implementations to "speculatively" load classes
> mentioned by Preload, enabling early field layout computations ("speculative"
> because the attempt may fail due to circularities, but succeed later)
> 
> - The categorization of attributes in 4.7 is not a great fit for Preload; maybe
> we need to redefine the categories a bit
> 
> - The definition of the Preload attribute could use more (perhaps non-normative)
> description of how it works, even though this is mostly below the level of the
> spec; 5.4 could also help clarify this
> 
> - The reference to the "start of object construction" in the table about
> ACC_STRICT is vague; maybe we can do better
> 
> - The 4.9.2 rule about ACC_STRICT is hard to parse, will be rephrased somehow
> 
> - 2.4 should say more about "sameness" as it relates to "identity"