RFR: 8268229: Aarch64: Use Neon in intrinsics for String.equals [v3]

Andrew Haley aph at openjdk.java.net
Mon Jul 5 09:23:49 UTC 2021


On Mon, 5 Jul 2021 08:19:51 GMT, Nick Gasson <ngasson at openjdk.org> wrote:

>> * Why we unroll the loop ?
>> *  It is found that these codes degrades performance 
>>  ```
>>     br(LE, B16);
>>     subs(cnt1, cnt1, wordSize);
>>     br(LE, B24);
>>     subs(cnt1, cnt1, wordSize);
>> 
>>  We unroll the loop to remove these comparsion.
>
> But we need to balance performance against code size, given that this is expanded frequently.

Nick is right. This unrolling at the call site is not going to be accepted.

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PR: https://git.openjdk.java.net/jdk/pull/4423


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