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

[Quan Anh Mai]

On Tue, 3 Sep 2024 13:56:24 GMT, Emanuel Peter <epeter 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 pull request now contains 11 commits:
>> 
>>  - fix compile errors
>>  - Merge branch 'master' into unsignedbounds
>>  - add comments
>>  - Merge branch 'master' into unsignedbounds
>>  - fix release build
>>  - add comments, group arguments to reduce C-style reference passing arguments
>>  - fix tests, add verify
>>  - add unit tests
>>  - fix template parameter
>>  - refactor
>>  - ... and 1 more: https://git.openjdk.org/jdk/compare/d8e4d3f2...d5ad9f1a
>
> 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.

> src/hotspot/share/opto/rangeinference.cpp line 444:
> 
>> 442:       return nullptr;
>> 443:     }
>> 444:     os::snprintf_checked(buf, buf_size, "%s+" INT32_FORMAT, xname, jint(n - origin));
> 
> Was there an explicit choice to use buffers, instead of `outputStream`?

I'm not sure, it is just the currently used method.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r1742662458
PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r1742663315