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How to use the Intel AVX in Java?
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How do I use the Intel AVX vector instruction set from Java? It's a simple question but the answer seems to be hard to find.

Tatouay answered 27/12, 2014 at 9:17 Comment(4)
What exactly are you trying to achieve? Can you clarify your question? – Oily
I want to perform bitwise AND and XOR computations using the AVX rather than Java int arrays. – Tatouay
Possible duplicate: https://mcmap.net/q/211540/-do-any-jvm-39-s-jit-compilers-generate-code-that-uses-vectorized-floating-point-instructions/523744 – Ashcroft
A related keyword is SIMD – Civism
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19

As I know, most current Java JVM JITters don't support automatic vectorization or just do that for very simple loops, so you're out of luck.

In Mono's .NET implementation there's Mono.Simd for manual vector code emission and then later MS introduced the System.Numeric.Vectors. Unfortunately there's nothing similar in Java. I don't know if Java's vector class is vectorized using SIMD or not but I don't think it is.

If you want to use CPU-specific features like AVX then your only choice is JNI. Write your bottle neck part in C or C++ and call it from Java

There's another solution by Scala to use vectorized code without modifying the JVM that you can read in How we made the JVM 40x faster

Update:

Now there's a new Vector API being developed for writing vector code manually

Provide an initial iteration of an incubator module, jdk.incubator.vector, to express vector computations that reliably compile at runtime to optimal vector hardware instructions on supported CPU architectures and thus achieve superior performance to equivalent scalar computations.

https://openjdk.java.net/jeps/338

Read more:

Plait answered 27/12, 2014 at 10:3 Comment(1)
UPDATE: JEP-338 was delivered in java 16 at 2021/02/18. @SoftwareEngineer – Wilden
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Depending on the work, you may not have to do much. AVX2 is used automatically by JVM on some operations on Arrays and String, on supporting platforms like Haswell onwards and Xeon v3 onwards.

https://software.intel.com/en-us/articles/java-application-performance-improvement-with-intel-xeon-processor-e7-v3

https://en.wikipedia.org/wiki/Advanced_Vector_Extensions#CPUs_with_AVX2

From Ryzen 3 / Epyc Rome, you'll also have single cycle AVX2 on AMD processors: https://www.anandtech.com/print/14525/amd-zen-2-microarchitecture-analysis-ryzen-3000-and-epyc-rome

Direct use of the instructions and intrinsics are not easily available though.

Mathura answered 14/6, 2019 at 8:17 Comment(0)
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Java 19 now supports SIMD with new Vector Intrinsics API , this API much faster then JNI implementations. Its directly converting your java method calls to inline assembly instructions. Checkout : https://vksegfault.github.io/posts/java-simd/

Maitund answered 25/5, 2022 at 11:39 Comment(0)
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To use these operations from Java you need a library like JavaCV This library enables vector operations for both Intel Processors and GPUs like NVIDIA.

Certification answered 27/12, 2014 at 10:15 Comment(2)
This seems a collection of special-purpose routines, not a general toolkit for vector operations. Am I missing something? – Exponent
@AleksandrDubinsky for a general purpose API I would use JavaCL which is also a wrapper for OpenCL. . – Certification
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One option is to use Aparapi and install the Intel OpenCL driver. (Your code will be vectorized to work on both CPUs and GPUs, as long as an appropriate OpenCL driver is installed.)

Another option is to use JNI and call a C++ function that uses AVX intrinsics or was auto-vectorized by a compiler.

Exponent answered 18/2, 2015 at 21:22 Comment(0)
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Check for yeppp library. It has java binding and its very fast cross platform SIMD Library.

http://www.yeppp.info

Maitund answered 30/5, 2015 at 11:4 Comment(1)
the above link has been dead. Check sites.google.com/site/yeppplibrary – Plait

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