On Thu, 14 Mar 2024 00:00:53 GMT, Shaojin Wen <d...@openjdk.org> wrote:
>> The current BigDecimal(String) constructor calls String#toCharArray, which
>> has a memory allocation.
>>
>>
>> public BigDecimal(String val) {
>> this(val.toCharArray(), 0, val.length()); // allocate char[]
>> }
>>
>>
>> When the length is greater than 18, create a char[]
>>
>>
>> boolean isCompact = (len <= MAX_COMPACT_DIGITS); // 18
>> if (!isCompact) {
>> // ...
>> } else {
>> char[] coeff = new char[len]; // allocate char[]
>> // ...
>> }
>>
>>
>> This PR eliminates the two memory allocations mentioned above, resulting in
>> an approximate 60% increase in performance..
>
> Shaojin Wen has updated the pull request incrementally with one additional
> commit since the last revision:
>
> bug fix for CharArraySequence#charAt
src/java.base/share/classes/java/math/BigDecimal.java line 598:
> 596: // First compact case, we need not to preserve the
> character
> 597: // and we can just compute the value in place.
> 598: for (; ; c = val.charAt(++offset)) {
This needs to be simplified. Let's at least do this, which is more honest:
while (true) {
...
c = val.charAt(++offset);
}
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/18177#discussion_r1532864646
