[code-reflection] RFR: [hat][proposal] Adding notion of local thread ids and local group sizes int HAT

[Juan Fumero]

On Mon, 18 Aug 2025 14:10:45 GMT, Juan Fumero <duke at openjdk.org> wrote:

> This PR extends the `KernelContext` API to access local thread ids and group sizes. 
> 
> It keeps compatibility with the prev. API, thus, it maintains the `kernelcontext.x` and `kernelcontext.maxX` thread accessors. However, we might remove this in near future in favour for the kernelContext.gix and `kernelcontext.gsx`. 
> This is just a proposal.
> 
> Simple example:
> 
> 
> @CodeReflection
>     private static void assign(@RO KernelContext context, @RW S32Array arrayA, @RW S32Array arrayB, @RW S32Array arrayC) {
>         int gix = context.gix;
>         int lix = context.lix;
>         int lsx = context.lsx;
>         int bsx = context.bsx;
>         arrayA.array (gix, lix);    // Store local thread id
>         arrayB.array(gix, lsx);    // Store local size
>         arrayC.array(gix, bsx);   // Store thread block id
>     }
> 
> 
> How to test:
> 
> 
> 
> # For OpenCL
>  java -cp job.jar hat.java exp ffi-opencl $@                                                                                            
>  
> # For CUDA                                                                                                                                        
>  java -cp job.jar hat.java exp ffi-cuda $@ 
> 
> 
> Still a draft PR until double checking with the CUDA backend.

Ready for review

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PR Comment: https://git.openjdk.org/babylon/pull/527#issuecomment-3200049316