RFR: 8339704: Refactor StringConcatHelper simpleConcat

[Claes Redestad]

On Tue, 27 Aug 2024 10:09:09 GMT, Shaojin Wen <swen at openjdk.org> wrote:

> The string concatenation of the java.base module is implemented using StringBuilder. By providing a series of concat methods in StringConcatHelper, it is used in the java.lang package to replace string concatenation.
> 
> These concat methods can also be exposed through JLA for use by other packages, such as java.lang.constant.
> 
> These concat methods can replace Concat1 and become part of StringConcatFactory#simpleConcat

src/java.base/share/classes/java/lang/StringConcatHelper.java line 731:

> 729:     @ForceInline
> 730:     static String concat(String prefix, float value, String suffix) {
> 731:         if (prefix == null) prefix = "null";

Since we'll never bind in `null` values all these `prefix == null` are likely redundant unless we expose them to users. Which we probably shouldn't. It's a good thing this PR actually removes some shared secrets rather than adding new ones.

src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java line 518:

> 516:             mh = MethodHandles.insertArguments(mh, 2, suffix);
> 517:             return MethodHandles.insertArguments(mh, 0, prefix);
> 518:         } else if (paramCount == 2 && constants[1] == null) {

All `constants` are non-null (see `parseRecipe`)
Suggestion:

        } else if (paramCount == 2 && constants[1].isEmpty()) {

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PR Review Comment: https://git.openjdk.org/jdk/pull/20726#discussion_r1749234619
PR Review Comment: https://git.openjdk.org/jdk/pull/20726#discussion_r1749233891