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

[Shaojin Wen]

On Thu, 15 May 2025 15:37:39 GMT, fabioromano1 <duke at openjdk.org> wrote:

>> Some changes in `Biginteger`s' bit operations that increase the code readability and slightly optimize the execution time.
>
> fabioromano1 has updated the pull request incrementally with one additional commit since the last revision:
> 
>   make magBitLength() an instance method

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

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

PR Review Comment: https://git.openjdk.org/jdk/pull/25166#discussion_r2092060927