RFR: 8315066: Add unsigned bounds and known bits to TypeInt/Long [v22]

[Quan Anh Mai]

On Fri, 20 Sep 2024 11:59:50 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   formality
>
> src/hotspot/share/opto/rangeinference.hpp line 70:
> 
>> 68: template <class U>
>> 69: class KnownBits {
>> 70:   static_assert(std::is_unsigned<U>::value, "bit info should be unsigned");
> 
> Since you are forcing bit info should correspond to unsigned type, it will be good to add KnownBits.minValue() and KnownBits.maxValue() routines where,
> 
> MinValue = KnownBits.ONES (assuming all the unknown bits are 0s)
> MaxValue = ~KnownBits.ZERO (assuming all unknown bits are 1s)

I would prefer to add them when they are needed.

> src/hotspot/share/opto/rangeinference.hpp line 155:
> 
>> 153:     return t1->_lo == t2->_lo && t1->_hi == t2->_hi && t1->_ulo == t2->_ulo && t1->_uhi == t2->_uhi &&
>> 154:           t1->_bits._zeros == t2->_bits._zeros && t1->_bits._ones == t2->_bits._ones;
>> 155:   }
> 
> For clarity, Expression can be broken into separate signed, unsigned and known bit comparison followed by logical anding.

That's a really good idea, I have done that.

> src/hotspot/share/opto/type.hpp line 619:
> 
>> 617:  * it by one, which contradicts the assumption of the TypeInt being canonical.
>> 618:  *
>> 619:  * 2. Either _lo == jint(_lo) and _hi == jint(_uhi), or all elements of a
> 
> Suggestion:
> 
>  * 2. Either _lo == jint(_ulo) and _hi == jint(_uhi), or all elements of a

Thanks for noticing.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r1768965322
PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r1768958772
PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r1768959515