RFR: 8349176: Speed up Integer/Long.toString via Unsafe.allocateUninitializedArray

[Chen Liang]

On Wed, 29 Jan 2025 16:36:24 GMT, Shaojin Wen <swen at openjdk.org> wrote:

> The byte[] allocated in Integer/Long.toString is fully filled, so we can use Unsafe.allocateUninitializedArray to create byte[] to improve performance.

src/java.base/share/classes/java/lang/StringConcatHelper.java line 559:

> 557:     static byte[] newArray(int length) {
> 558:         return (byte[]) UNSAFE.allocateUninitializedArray(byte.class, length);
> 559:     }

I think we should keep this check, as string concatenation seems to use this to throw OOME.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23353#discussion_r1934548644