RFR: 8315066: Add unsigned bounds and known bits to TypeInt/Long [v7]

[Vladimir Kozlov]

On Tue, 3 Sep 2024 20:40:05 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> src/hotspot/share/opto/rangeinference.cpp line 94:
>> 
>>> 92:     return {true, false, {}};
>>> 93:   }
>>> 94:   T new_hi = ~adjust_lo(~bounds._hi, {bits._ones, bits._zeros});
>> 
>> Wow, that looks like some magic 😆 Can you please explain this?
>
> So `~` is a strictly decreasing function in the unsigned integer domain, so we just do a bitwise negation, compute the adjustment there and switch back.

This deserves comment. When next person need to touch this code it will be "magic" and confusing.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r1742784955