On Thu, 25 Sep 2025 12:26:27 GMT, fabioromano1 <d...@openjdk.org> wrote:
>> A formula to lower the overestimate for the precision of an exact quotient,
>> without introducing too expensive operations of division on numerator and
>> denominator.
>
> fabioromano1 has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Comments
Otherwise looks good.
src/java.base/share/classes/java/math/BigDecimal.java line 1807:
> 1805: * - if i > j, then a/b = (a/b') ⋅ 5^(i-j) / 10^i.
> 1806: */
> 1807: BigInteger den = divisor.unscaledValue();
Maybe "synchronize" the names between the comment and the code.
For example, either rename `powsOf2` to `i` or the other way round.
Alternatively, provide a "translation table", e.g., `i` <-> `powsOf2`, etc.
src/java.base/share/classes/java/math/BigDecimal.java line 1815:
> 1813: BigInteger[] qr;
> 1814: int i;
> 1815: for (i = 0; ; i++) {
What about a comment explaining the idea of this and the following fast loops
using 5^(2^i) powers to find the correct `powsOf5` (the `j` in the comment)?
test/micro/org/openjdk/bench/java/math/BigDecimalDivide.java line 2:
> 1: /*
> 2: * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
Suggestion:
* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
test/micro/org/openjdk/bench/java/math/BigDecimalDivide.java line 153:
> 151: }
> 152: }
> 153: }
It would be useful to publish the "before" and "after" results of running these
benchmarks.
-------------
PR Review: https://git.openjdk.org/jdk/pull/27271#pullrequestreview-3268234720
PR Review Comment: https://git.openjdk.org/jdk/pull/27271#discussion_r2379473964
PR Review Comment: https://git.openjdk.org/jdk/pull/27271#discussion_r2379476985
PR Review Comment: https://git.openjdk.org/jdk/pull/27271#discussion_r2379478040
PR Review Comment: https://git.openjdk.org/jdk/pull/27271#discussion_r2379479325
