RFR: 8350896: Integer/Long.compress gets wrong type from CompressBitsNode::Value [v15]

[Tobias Hartmann]

On Wed, 16 Jul 2025 10:43:34 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Hi All,
>> 
>> This bugfix patch fixes incorrect value computation for Integer/Long. compress APIs.
>> 
>> Problems occur with a constant input and variable mask where the input's value is equal to the lower bound of the mask value., In this case, an erroneous value range estimation results in a constant value. Existing value routine first attempts to constant fold the compression operation if both input and compression mask are constant values; otherwise, it attempts to constrain the value range of result based on the upper and lower bounds of mask type.
>> 
>> New IR test covers the issue reported in the bug report along with a case for value range based logic pruning.
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Refine lower bound computation

This looks good to me and I think you addressed all the comments that Emanuel had. Let's wait for another day or two in case someone else wants to take a look as well.

In the meantime, please request approval for integration into JDK 25 since we are know at RDP 2:
https://openjdk.org/jeps/3#Fix-Request-Process

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Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23947#pullrequestreview-3036859676