<i18n dev> RFR: 8358880: Performance of parsing with DecimalFormat can be improved [v3]

[Johannes Graham]

On Wed, 11 Jun 2025 23:47:01 GMT, Justin Lu <jlu at openjdk.org> wrote:

>> Johannes Graham has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Address review comments
>
> src/java.base/share/classes/jdk/internal/math/FloatingDecimal.java line 1841:
> 
>> 1839: 
>> 1840:     static ASCIIToBinaryConverter readDoubleSignlessDigits(int decExp, char[] digits, int length) {
>> 1841:         if (decExp < MIN_DECIMAL_EXPONENT) {
> 
> Is this check needed? I think `ASCIIToBinaryConverter` will return the proper zero value when `doubleValue()` is invoked. 
> 
> 
>   if (decExponent < MIN_DECIMAL_EXPONENT - 1) {
>       return (isNegative) ? -0.0 : 0.0;
> 
> 
> And if this explicit check is a shortcut, I don't think we would need one for an edge case.

Unfortunately some check is required (a test fails), but I now realize what I had was wrong. The issue is that on line 1084 (https://github.com/openjdk/jdk/pull/25644/files#diff-79e6fd549b5ec5e7f49658581beddcb07fcbb0c09ae8e1117c385b66514da6d2R1084)) exp can overflow and become positive again. I've updated the check to avoid the overflow.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25644#discussion_r2143060934