RFR: 8305783: x86_64: Optimize AbsI and AbsL

Sun Apr 9 09:48:49 UTC 2023

On Sun, 9 Apr 2023 09:41:08 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

> Hi,
> 
> This patch optimizes the sequence emitted by `AbsINode` and `AbsLNode` to save some instructions and 1 temp register. Please take a look and kindly leave your reviews.
> 
> Thanks a lot.

Running the patch on `org.openjdk.bench.java.lang.MathBench` shows noticeable improvement:

                                            Before                    After
    Benchmark           Mode  Cnt        Score       Error        Score       Error   Units   Change
    MathBench.absInt   thrpt    8  2848176.368 ± 18552.810  3442310.540 ± 65838.237  ops/ms  +20.86%
    MathBench.absLong  thrpt    8  2851886.891 ± 17565.736  3389983.543 ± 36466.553  ops/ms  +18.87%

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PR Comment: https://git.openjdk.org/jdk/pull/13402#issuecomment-1501088764