On Tue, 25 Nov 2025 22:23:36 GMT, Dhamoder Nalla <[email protected]> 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** >> <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";> >> >> <head> >> >> <meta name=ProgId content=OneNote.File> >> <meta name=Generator content="Microsoft OneNote 15"> >> </head> >> >> <body lang=en-US style='font-family:Calibri;font-size:11.0pt'> >> >> >> <div style='direction:ltr;border-width:100%'> >> >> <div style='direction:ltr;margin-top:0in;margin-left:0in;width:12.9277in'> >> >> <div style='direction:ltr;margin-top:0in;margin-left:0in;width:12.9277in'> >> >> <div style='direction:ltr'> >> >> 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 >> >> </div> >> >> </div> >> >> </div> >> >> </div> >> >> >> </body> >> >> </html> >> >> >> >> **After adding Math.log intrinsic** >> >> <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";> >> >> <head> >> >> <meta name=ProgId content=OneNote.File> >> <meta name=Generator content="Microsoft OneNote 15"> >> </head> >> >> <body lang=en-US style='font-family:Calibri;font-size:11.0pt'> >> >> >> <div style='direction:ltr;border-width:100%'> >> >> <div style='direction:ltr;margin-top:0in;margin-left:0in;width:12.9277in'> >> >> <div style='direction:ltr;margin-top:0in;margin-left:0in;width:12.9277in'> >> >> <div style='direction:ltr'> >> >> 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 >> >> >> </div> >> >> </div> >> >> </div> >> >> </div> >> >> >> </body> >> >> </html> > > Dhamoder Nalla has updated the pull request incrementally with one additional > commit since the last revision: > > [AArch64] Math.log is 10% slower than StrictMath.log on aarch64 src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp line 8812: > 8810: address generate_dlog() { > 8811: __ align(CodeEntryAlignment); > 8812: StubCodeMark mark(this, "StubRoutines", "dlog"); This StubCodeMark needs to be declared with a StubId as argument. See other stub generators in this file or the equivalent code in `cpu/x86/stubGenerator_x86_64_log.cpp` for an example of what it should look like. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/28306#discussion_r2564133696
