RFR: 8367657: C2 SuperWord: NormalMapping demo from JVMLS 2025 [v6]

[Galder Zamarreño]

On Wed, 17 Sep 2025 14:35:23 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Demo from here:
>> https://inside.java/2025/08/16/jvmls-hotspot-auto-vectorization/
>> 
>> Cleaned up and enhanced with a JTREG and IR test.
>> I also added some additional "generated" normal maps from height functions.
>> And I display the resulting image side-by-side with the normal map.
>> 
>> I decided to put it in a new directory `compiler.gallery`, anticipating other compiler tests that are both visually appealing (i.e. can be used for a "gallery") and that we may want to back up with other tests like IR testing.
>> 
>> There is a **stand-alone** way to run the demo:
>> `java test/hotspot/jtreg/compiler/gallery/NormalMapping.java`
>> (though it may only run with JDK22+, probably due some amber features)
>> 
>> **Quick Perforance Numbers**, running on my avx512 laptop.
>> default / AVX3: 105 FPS
>> AVX2: 82 FPS
>> AVX1: 50 FPS
>> No vectorization: 19 FPS
>> GraalJIT: 13 FPS (`jdk-26-ea+5` - probably issue with vectorization / inlining?)
>> 
>> Here some snapshots, but **I really recommend pulling the diff and playing with it, it looks much better in motion**:
>> <img width="2000" height="991" alt="image" src="https://github.com/user-attachments/assets/a693fac8-ecf0-43f2-914b-25f76c2f425d" />
>> <img width="2000" height="997" alt="image" src="https://github.com/user-attachments/assets/c2202e6b-6a90-4f90-a3ca-b73304e25905" />
>> <img width="1997" height="992" alt="image" src="https://github.com/user-attachments/assets/0d6da304-6bb9-4b25-9a7b-72019b02d95e" />
>> <img width="1992" height="994" alt="image" src="https://github.com/user-attachments/assets/9f5f7426-0678-45af-a3eb-ac092c262d4c" />
>
> Emanuel Peter has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Update test/hotspot/jtreg/compiler/gallery/TestNormalMapping.java
>    
>    Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
>  - Update test/hotspot/jtreg/compiler/gallery/NormalMapping.java
>    
>    Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>

Great demo! I run it on my M4 Pro at 220 FPS with default flags 😎

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Marked as reviewed by galder (Author).

PR Review: https://git.openjdk.org/jdk/pull/27282#pullrequestreview-3242796809