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

[Chen Liang]

On Mon, 12 May 2025 01:46:25 GMT, David Schlosnagle <duke at openjdk.org> wrote:

>> Some changes in `Biginteger`s' bit operations that increase the code readability and slightly optimize the execution time.
>
> src/java.base/share/classes/java/math/BigInteger.java line 2642:
> 
>> 2640:         }
>> 2641:         // (this.abs().bitLength() - 1L) * exponent + 1L > Integer.MAX_VALUE
>> 2642:         if (scaleFactor + bitsToShift - exponent >= Integer.MAX_VALUE) {
> 
> If this is overflow sensitive code, should this avoid adding on the left hand side?
> 
> Suggestion:
> 
>         if (scaleFactor - exponent >= Integer.MAX_VALUE - bitsToShift) {

I think we are fine here, `scaleFactor` is already `long`

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PR Review Comment: https://git.openjdk.org/jdk/pull/25166#discussion_r2083704486