RFR: 8373999: C2: apply KnownBits and unsigned bounds to Add / Sub operations [v4]

[Quan Anh Mai]

On Wed, 14 Jan 2026 09:33:44 GMT, Benoît Maillard <bmaillard at openjdk.org> wrote:

>> Quan Anh Mai has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - copyright year
>>  - Merge branch 'master' into addsub
>>  - Merge branch 'master' into addsub
>>  - include order
>>  - Improve Add/SubNode::Value with unsigned bounds and known bits
>
> src/hotspot/share/opto/rangeinference.hpp line 419:
> 
>> 417:         // Similarly, if st1._lo < 0 and st2._lo < 0, we have:
>> 418:         // - 2^(n-1) <= st1._ulo <= v1 <= st1._uhi <= 2^n - 1
>> 419:         // - 2^(n-1) <= st2._ulo <= v2 <= st2._uhi <= 2^n - 1
> 
> At first I thought the `-` character was "minus", which confused me a little. Maybe we should avoid this, and only have indentation?

Yes you are right, very questionable from my side here

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/28897#discussion_r2690440286