RFR: JDK-8302323 Add repeat methods to StringBuilder/StringBuffer [v8]

[Jim Laskey]

On Tue, 14 Mar 2023 10:14:44 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Jim Laskey has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Expand test for StringBuffer and illegal code points
>
> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1832:
> 
>> 1830:         if (isLatin1 && StringLatin1.canEncode(c)) {
>> 1831:             byte b = (byte)c;
>> 1832:             for (int index = this.count; index < limit; index++) {
> 
> This loop could even be replaced with `Arrays.fill(value, this.count, limit, b)` - a plausible candidate for intrinsification?  There's an added range check in that method, however, but that shouldn't be too hard for the JIT to eliminate.

I bounded back and forth on this one.  Performance is a little give and take.  Will use Arrays.fill for maintainability.

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PR Review Comment: https://git.openjdk.org/jdk/pull/12728#discussion_r1149648398