Withdrawn: 8308776: [AArch64] Math.log is 10% slower than StrictMath.log on aarch64

Thu Jan 22 06:27:46 UTC 2026

On Thu, 13 Nov 2025 20:41:56 GMT, Dhamoder Nalla <dhanalla at openjdk.org> wrote:

> This PR Introduces an optimized AArch64 intrinsic for Math.log using reciprocal refinement and a table-driven polynomial.
> Improves throughput for double logarithms while preserving IEEE-754 corner case behavior (±0, subnormals, negatives, NaN).
> 
> 
> 
> The micro-benchmark results from MathBench and StrictMathBench below show the performance improvement of Math.log:
> 
> 
> **Before change**
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> Benchmark | Mode | Cnt | Score | Error | Units
> -- | -- | -- | -- | -- | --
> MathBench.logDouble | thrpt | 10 | **15549.705** | ±357.439 | ops/ms
> StrictMathBench.logDouble | thrpt | 10 | 219408.158 | ±16484.680 | ops/ms
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> **After adding Math.log intrinsic**
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> <html xmlns:o="urn:schemas-microsoft-com:office:office"
> xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882"
> xmlns="http://www.w3.org/TR/REC-html40">
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> <head>
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> <meta name=ProgId content=OneNote.File>
> <meta name=Generator content="Microsoft OneNote 15">
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> Benchmark | Mode | Cnt | Score | Error | Units
> -- | -- | -- | -- | -- | --
> MathBench.logDouble | thrpt | 10 | **300086.773** | ±6675.936 | ops/ms
> StrictMathBench.logDouble | thrpt | 10 | 226521.817 | ±4038.975 | ops/ms
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This pull request has been closed without being integrated.

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PR: https://git.openjdk.org/jdk/pull/28306