RFR: 8273100: Improve AbstractStringBuilder.append(String) when using CompactStrings [v3]

[Сергей Цыпанов]

On Mon, 30 Aug 2021 13:54:13 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1730:
>> 
>>> 1728:     }
>>> 1729: 
>>> 1730:     private void putStringAt(int index, String str) {
>> 
>> Can we replace all the calls to this method with calls to previous method as `putStringAt(index, str, 0, str.length())` taking into account that in all usecases `str.length()` is already calculated into a local var?
>
> No, I don't think so. The only use of this I can find is at line 1298 which effectively adds a substring: `putStringAt(dstOffset, (String) s, start, end);`

What about lines 582, 1003 and 1175? E.g. 582

public AbstractStringBuilder append(String str) {
    if (str == null) {
        return appendNull();
    }
    int len = str.length();
    ensureCapacityInternal(count + len);
    putStringAt(count, str);             // couldn't it be putStringAt(count, str, 0, len);
    count += len;
    return this;
}

Doing this here and in other places allows  to rid `private void putStringAt(int index, String str)` completely and reduce one nested method call, right?

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PR: https://git.openjdk.java.net/jdk/pull/5291