[lworld] RFR: 8359370: [lworld] allow instance fields of identity classes to be readable in the prologue phase [v19]

[Maurizio Cimadamore]

On Fri, 29 Aug 2025 20:10:39 GMT, Vicente Romero <vromero at openjdk.org> wrote:

>> Before this fix only strict fields were readable in the prologue phase. The proposed fix should allow any instance fields of identity classes to be readable in the prologue phase. This implies changes in flow analysis as before we were only tracking final and strict fields. There is also some "cooperation" needed in the code to detect cases when reading a field is not allowed in the prologue phase. For example some methods in Resolve don't have all the needed information at the moment they are dealing with some ASTs and part of the processing needs to be done in Attr
>> 
>> TIA
>> 
>> This PR is a remake of https://github.com/openjdk/valhalla/pull/1490
>
> Vicente Romero has updated the pull request incrementally with one additional commit since the last revision:
> 
>   some documentation

Do we still need the changes in `Attr.checkAssignable` -- e.g. flexible constructor bodies used to check some extra properties in there. Now that we have an LHS variable in the prologue scanner, I wonder if we can unify the checks?

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PR Review: https://git.openjdk.org/valhalla/pull/1523#pullrequestreview-3173319602