RFR: 8356709: Avoid redundant String formatting in BigDecimal.valueOf(double)

[Johannes Graham]

On Sun, 11 May 2025 16:22:11 GMT, Johannes Graham <duke at openjdk.org> wrote:

> Optimize `BigDecimal.valueOf(double)` by using `FormattedFPDecimal` instead of converting to decimal string and then parsing it. This results in an approximate 6x improvement for me.

On Aarch64 M4:

Benchmark                                Mode  Cnt   Score   Error  Units
+ BigDecimals.testValueOfWithDouble        avgt   15   9.913 ± 0.080  ns/op
- BigDecimals.testValueOfWithDoubleString  avgt   15  65.846 ± 0.801  ns/op

src/java.base/share/classes/java/math/BigDecimal.java line 1398:

> 1396:     public static BigDecimal valueOf(double val) {
> 1397:         if (!Double.isFinite(val)) {
> 1398:             throw new NumberFormatException("Infinite or NaN");

Note, this changes the exception message. The new message is consistent with `new BigDecimal(double)`

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PR Comment: https://git.openjdk.org/jdk/pull/25173#issuecomment-2869969120
PR Review Comment: https://git.openjdk.org/jdk/pull/25173#discussion_r2083568201