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sycl: add REPEAT_BACK operation support#16734

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NeoZhangJianyu merged 5 commits intoggml-org:masterfrom
shani-f:feature/sycl-repeat-back
Oct 27, 2025
Merged

sycl: add REPEAT_BACK operation support#16734
NeoZhangJianyu merged 5 commits intoggml-org:masterfrom
shani-f:feature/sycl-repeat-back

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@shani-f shani-f commented Oct 23, 2025

Summary

Implements the REPEAT_BACK operator for the SYCL backend, enabling mirrored repetition of tensor data on SYCL devices.
The implementation matches the behavior of the existing CPU version.

Changes

  • Added repeat_back.cpp with SYCL kernel implementation
  • Added dispatch in ggml-sycl.cpp under GGML_OP_REPEAT_BACK
  • Integrated into the SYCL compute pipeline

Implementation

  • Supports tensors up to 4 dimensions
  • Performs reflection-based repetition using modular indexing
  • Parallelized with parallel_for using range<3>
  • Efficient indexing for mirrored boundaries
  • Zero-overhead path for non-repeated cases

Testing

  • Verified results match the CPU implementation
  • Checked correctness on multi-dimensional tensors
  • Tested reflection accuracy on all tensor edges

Performance

  • Optimized index computation (no redundant divisions)
  • Memory accesses follow contiguous layout
  • Minimal kernel footprint and register usage

Compatibility

  • Supports F32 tensors
  • Works with Level Zero and OpenCL backends
  • Follows existing SYCL backend design conventions

@github-actions github-actions bot added ggml changes relating to the ggml tensor library for machine learning SYCL https://en.wikipedia.org/wiki/SYCL - GPU programming language labels Oct 23, 2025
@shani-f shani-f force-pushed the feature/sycl-repeat-back branch from b80dce9 to d3e88bc Compare October 23, 2025 10:12
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shani-f commented Oct 23, 2025 •
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@CISC @NeoZhangJianyu
this PR adds SYCL backend support for GGML_OP_REPEAT_BACK.
All tests pass locally and the implementation currently supports F32 tensors.

@CISC CISC requested a review from NeoZhangJianyu October 26, 2025 10:19
CISC
CISC reviewed Oct 26, 2025
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shani-f and others added 3 commits October 26, 2025 12:37
@shani-f @CISC
Update ggml/src/ggml-sycl/repeat_back.cpp
020dba5 
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
@shani-f @CISC
Update ggml/src/ggml-sycl/repeat_back.hpp
5c36f73 
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
@shani-f @CISC
Update ggml/src/ggml-sycl/ggml-sycl.cpp
a18fbd7 
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
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shani-f commented Oct 26, 2025

Hello @CISC @NeoZhangJianyu,
I noticed that the two failing checks are WebGPU and WebUI tests, which seem unrelated to my changes.
I’d appreciate it if you could let me know what the next step is toward merging.
Thank you!

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CISC commented Oct 26, 2025

I noticed that the two failing checks are WebGPU and WebUI tests, which seem unrelated to my changes. I’d appreciate it if you could let me know what the next step is toward merging. Thank you!

It happens sometimes, I've re-run them, but don't worry about it. @NeoZhangJianyu will review when time permits.

NeoZhangJianyu
NeoZhangJianyu approved these changes Oct 27, 2025
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It's good job!

Thank you!

@NeoZhangJianyu NeoZhangJianyu merged commit 59fc1ec into ggml-org:master Oct 27, 2025
137 of 139 checks passed
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shani-f commented Oct 27, 2025 via email

@shani-f shani-f mentioned this pull request Oct 30, 2025
Merged
Anico2 added a commit to Anico2/llama.cpp that referenced this pull request Jan 15, 2026
@Anico2 @CISC
sycl: add REPEAT_BACK operation support (ggml-org#16734)
da14dea 
* SYCL repeat_back v1 — add core op + switch case

* Implement repeat_back SYCL operation and minor fixes

* Update ggml/src/ggml-sycl/repeat_back.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update ggml/src/ggml-sycl/repeat_back.hpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update ggml/src/ggml-sycl/ggml-sycl.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
blime4 referenced this pull request in blime4/llama.cpp Feb 5, 2026
@shani-f @CISC
sycl: add REPEAT_BACK operation support (#16734)
f0f0b1c 
* SYCL repeat_back v1 — add core op + switch case

* Implement repeat_back SYCL operation and minor fixes

* Update ggml/src/ggml-sycl/repeat_back.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update ggml/src/ggml-sycl/repeat_back.hpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update ggml/src/ggml-sycl/ggml-sycl.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
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ggml changes relating to the ggml tensor library for machine learning SYCL https://en.wikipedia.org/wiki/SYCL - GPU programming language

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