On Sun, 26 Jan 2025 19:31:08 GMT, Johannes Graham <d...@openjdk.org> wrote:
>> Continue to complete PR #16006 and PR #21593 to improve BigDecimal::toString
>> and BigDecimal::toPlainString performance and reduce duplicate code
>
> src/java.base/share/classes/java/math/BigDecimal.java line 3538:
>
>> 3536: return (signum < 0 ? "-0." : "0.").concat(intString);
>> 3537: } else if (insertionPoint > 0) { /* Point goes inside intVal */
>> 3538: buf = new StringBuilder();
>
> Could calculate the precise size for the StringBuilder
The performance will degrade if you precompute the length of the StringBuilder.
> src/java.base/share/classes/java/math/BigDecimal.java line 3542:
>
>> 3540: buf.append('-');
>> 3541: buf.append(intString)
>> 3542: .insert(insertionPoint + (signum < 0 ? 1 : 0),
>> '.');
>
> Instead of the insert, could do an append of the prefix, then dot, then the
> suffix.
buf.append(intString, 0, insertionPoint)
.append('.')
.append(intString, insertionPoint, intString.length());
This is another way to write it, but the performance will be reduced.
> src/java.base/share/classes/jdk/internal/util/DecimalDigits.java line 347:
>
>> 345: * @return index of the most significant digit or minus sign, if
>> present
>> 346: */
>> 347: public static int getChars(long i, int index, char[] buf) {
>
> Before dropping this method, there is another candidate to use it here :
> https://github.com/openjdk/jdk/blob/1d2eb2fbaea700fc77b644b5eb5a8a7c40ede108/src/java.base/share/classes/jdk/internal/math/FloatingDecimal.java#L367
I took a look at the FloatingDecimal related code. The relevant code in
FloatingDecimal can be refactored and simplified so that the removed code does
not need to be used.
I submitted a PR to simplify FloatingDecimal
https://github.com/openjdk/jdk/pull/23311
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/23310#discussion_r1930019634
PR Review Comment: https://git.openjdk.org/jdk/pull/23310#discussion_r1930024839
PR Review Comment: https://git.openjdk.org/jdk/pull/23310#discussion_r1929539931
