Integrated: 8316582: Minor startup regression in 22-b15 due JDK-8310929

[温绍锦]

On Wed, 20 Sep 2023 09:12:48 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> This patch reverts the use of `ByteArrayLittleEndian` in `StringLatin1`. 
> 
> This use is the cause of a small (~1.5ms) startup regression in 22-b15. While a manageable startup regression in and of itself, the use of `VarHandles` in core utility classes brings an increased risk of bootstrap circularity issues, for example disqualifying the use of things like `Integers.toString` in some places.
> 
> Reverting this partially rolls back the performance improvement gained by JDK-8310929. It seems reasonable that the compiler can be enhanced to gain that loss back.

digitPair and Unsafe.putShort are a good combination. Can Unsafe be used here?


   public static void writeDigitPair(byte[] buf, int charPos, int value) {
        Unsafe.putShortUnaligned(
                buf,
                Unsafe.ARRAY_BYTE_BASE_OFFSET + pos,
                digitPair(value),
                false);
    }

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PR Comment: https://git.openjdk.org/jdk/pull/15836#issuecomment-1730456039