RFR: 8327147: Improve performance of Math ceil, floor, and rint for x86 [v2]

Tue Mar 5 22:40:47 UTC 2024

On Tue, 5 Mar 2024 00:08:05 GMT, Srinivas Vamsi Parasa <duke at openjdk.org> wrote:

>> The goal of this PR is to provide ~4x faster implementation of Math.ceil, Math.floor and Math.rint for x86_64 CPUs.
>> 
>> Below is the performance data on an Intel Tiger Lake machine. 
>> 
>> <html xmlns:v="urn:schemas-microsoft-com:vml"
>> xmlns:o="urn:schemas-microsoft-com:office:office"
>> xmlns:x="urn:schemas-microsoft-com:office:excel"
>> xmlns="http://www.w3.org/TR/REC-html40">
>> 
>> <head>
>> 
>> <meta name=ProgId content=Excel.Sheet>
>> <meta name=Generator content="Microsoft Excel 15">
>> <link id=Main-File rel=Main-File
>> href="file:///C:/Users/sparasa/AppData/Local/Temp/msohtmlclip1/01/clip.htm">
>> <link rel=File-List
>> href="file:///C:/Users/sparasa/AppData/Local/Temp/msohtmlclip1/01/clip_filelist.xml">
>> 
>> 
>> </head>
>> 
>> <body link="#0563C1" vlink="#954F72">
>> 
>> 
>> Benchmark | Stock JDK   (ops/ms) | This PR (ops/ms) | Speedup
>> -- | -- | -- | --
>> MathBench.ceilDouble | 547979 | 2170198 | 3.96
>> MathBench.floorDouble | 547979 | 2167459 | 3.96
>> MathBench.rintDouble | 547962 | 2130499 | 3.89
>> 
>> 
>> 
>> </body>
>> 
>> </html>
>
> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
> 
>   unify the implementation

So if we can still generate the non-AVX encoding of

`roundsd dst, src, mode`

isn't there still a false dependency problem with `dst`?

-------------

PR Comment: https://git.openjdk.org/jdk/pull/18089#issuecomment-1979755885