RFR: 8356891: Some code simplifications for basic BigIntegers' bit operations [v6]

[Raffaello Giulietti]

On Fri, 16 May 2025 13:30:01 GMT, fabioromano1 <duke at openjdk.org> wrote:

>> src/java.base/share/classes/java/math/BigInteger.java line 3860:
>> 
>>> 3858:                 && Integer.lowestOneBit(mag[0]) == mag[0]
>>> 3859:                 && numberOfTrailingZeroInts() == mag.length - 1
>>> 3860:             ? magBitLength() - 1 : magBitLength();
>> 
>> Suggestion:
>> 
>>         int[] mag = this.mag;
>>         return magBitLength() 
>>                 - (signum < 0
>>                    // Check if magnitude is a power of two
>>                    && Integer.lowestOneBit(mag[0]) == mag[0]
>>                    && numberOfTrailingZeroInts() == mag.length - 1
>>                    ? 1 : 0);
>> 
>> 
>> In this way, codeSize will drop from 52 to 45
>
> What is the usefulness of doing `int[] mag = this.mag;` at line 3856, since `bitLength()` does not access to `static` fields and `BigInteger` is not threadsafe, and therefore no race conditions occur?

I think the suggestion is fine.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25166#discussion_r2096038516