On Sat, 26 Apr 2025 16:44:26 GMT, fabioromano1 <d...@openjdk.org> wrote:
>> This PR optimizes `BigInteger.pow(int)` method. The primary enhancement in
>> `pow()` is not concerned most on execution time, but rather in memory
>> optimization, because the PR implementation does the "shift of the exponent"
>> squaring the result rather than the base, so the base is not squared like in
>> the current implementation, and this permits to save about half of the
>> memory.
>
> fabioromano1 has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Removed method used by nth-root
src/java.base/share/classes/java/math/BigInteger.java line 2717:
> 2715: int blockLen;
> 2716: for (int nLen = Integer.SIZE - nZeros; nLen > 0; nLen -=
> blockLen) {
> 2717: blockLen = maxExpLen < nLen ? maxExpLen : nLen;
`blockLen` can be defined in the loop like:
int blockLen = Math.min(maxExpLen, nLen);
src/java.base/share/classes/java/math/BigInteger.java line 2728:
> 2726: if (exp > 0) {
> 2727: BigInteger xToExp = powerCache[exp];
> 2728: if (xToExp == null) {
Can we extract the cache computation logic into a new method for clarity? Huge
methods hamper readability.
This use site will look like:
if (exp > 0) {
BigInteger xToExp = powerCache[exp];
if (xToExp == null) {
xToExp = computePower(powerCache, x, exp, maxExp);
}
}
`computePower` stores entries to `powerCache` whenever it computed something to
allow reuse.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/24690#discussion_r2061491416
PR Review Comment: https://git.openjdk.org/jdk/pull/24690#discussion_r2061492295
