Split IndextoOffset() into offline and online versions

[yucai-intel]

Divide indextoOffset() into two versions, offline and online, to reduce runtime overhead and as much as possible.

[Copilot]

Pull Request Overview

Split IndexToOffset into compile-time (static Dims) and runtime (-1) variants to reduce nvcc compilation time and refactor all kernel call sites to use the new template form. Key changes remove the previous contiguous fast path flag and introduce dimension template parameters across many XPU SYCL kernels.

• Introduced IndexToOffset<T, IndexType, Dims> and dynamic specialization with Dims = -1; removed strict/non-strict contiguous branching.
• Updated all kernel usages to pass an explicit Dims (positive, -1, or new sentinel -2) and added indexing_kind template parameters in RNN kernels.
• Replaced standard SYCL subgroup size attribute with Intel-specific attribute in one kernel.

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/comm/TensorInfo.h	Replaced old IndexToOffset implementation with compile-time and runtime (-1) variants, removed contiguous fast path.
src/ATen/native/xpu/sycl/WeightNormKernels.cpp	Updated all IndexToOffset calls to new API (runtime -1).
src/ATen/native/xpu/sycl/TensorModeKernel.cpp	Switched subgroup size attribute to Intel-specific and updated IndexToOffset usage.
src/ATen/native/xpu/sycl/TensorApplyUtils.h	Updated ApplyOp2 to use runtime (-1) IndexToOffset.
src/ATen/native/xpu/sycl/SummaryOpsKernels.cpp	Added ADims/BDims template params and updated IndexToOffset calls.
src/ATen/native/xpu/sycl/Sorting.cpp	Pass compile-time Dim to IndexToOffset.
src/ATen/native/xpu/sycl/ScanUtils.h	Migrated to runtime (-1) IndexToOffset calls.
src/ATen/native/xpu/sycl/RNNKernels.cpp	Added indexing_kind template parameter and adjusted macros to new IndexToOffset signature.
src/ATen/native/xpu/sycl/Indexing.h	Updated offset calculations to new runtime form.
src/ATen/native/xpu/sycl/Indexing.cpp	Added DstDim/SrcDim/IdxDim template params, macros now emit various Dims (including -2) for IndexToOffset.
src/ATen/native/xpu/sycl/Dropout.cpp	Added ADims / BDims template-based offset computation.

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Silv3S]

Hi @yucai-intel, I can't build torch-xpu-ops since this commit was merged. Does it require some dependency update?
I'm using Ubuntu 24.04.2 LTS with oneAPI Base Toolkit 2025.2.1

 /home/gta/pytorch/torch/include/ATen/native/xpu/sycl/TensorApplyUtils.h:139:11: error: too few template arguments for class template 'IndexToOffset'
    139 |         ? IndexToOffset<scalar1, IndexType>::get(linearIndex, a)
        |           ^
  /home/gta/torch-xpu-ops/src/comm/TensorInfo.h:155:8: note: template is declared here
    154 | template <typename T, typename IndexType, int Dims>
        | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    155 | struct IndexToOffset {
        |        ^
  In file included from /home/gta/torch-xpu-ops/src/ATen/native/quantized/sycl/FusedObsFakeQuantKernels.cpp:10:
  In file included from /home/gta/pytorch/torch/include/ATen/native/xpu/sycl/DistributionTemplates.h:11:
  /home/gta/pytorch/torch/include/ATen/native/xpu/sycl/TensorApplyUtils.h:144:11: error: too few template arguments for class template 'IndexToOffset'
    144 |         ? IndexToOffset<scalar2, IndexType>::get(linearIndex, b)
        |           ^
  /home/gta/torch-xpu-ops/src/comm/TensorInfo.h:155:8: note: template is declared here
    154 | template <typename T, typename IndexType, int Dims>
        | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    155 | struct IndexToOffset {
        |        ^
  2 errors generated.

[PawelSwider2000]

Hi @yucai-intel, I can't build torch-xpu-ops since this commit was merged. Does it require some dependency update? I'm using Ubuntu 24.04.2 LTS with oneAPI Base Toolkit 2025.2.1

 /home/gta/pytorch/torch/include/ATen/native/xpu/sycl/TensorApplyUtils.h:139:11: error: too few template arguments for class template 'IndexToOffset'
    139 |         ? IndexToOffset<scalar1, IndexType>::get(linearIndex, a)
        |           ^
  /home/gta/torch-xpu-ops/src/comm/TensorInfo.h:155:8: note: template is declared here
    154 | template <typename T, typename IndexType, int Dims>
        | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    155 | struct IndexToOffset {
        |        ^
  In file included from /home/gta/torch-xpu-ops/src/ATen/native/quantized/sycl/FusedObsFakeQuantKernels.cpp:10:
  In file included from /home/gta/pytorch/torch/include/ATen/native/xpu/sycl/DistributionTemplates.h:11:
  /home/gta/pytorch/torch/include/ATen/native/xpu/sycl/TensorApplyUtils.h:144:11: error: too few template arguments for class template 'IndexToOffset'
    144 |         ? IndexToOffset<scalar2, IndexType>::get(linearIndex, b)
        |           ^
  /home/gta/torch-xpu-ops/src/comm/TensorInfo.h:155:8: note: template is declared here
    154 | template <typename T, typename IndexType, int Dims>
        | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    155 | struct IndexToOffset {
        |        ^
  2 errors generated.

@Silv3S Most likely content of pytorch/torch/include/ is outdated. Manually removing it helped for me, but this file should be updated automatically

Seems that this part of: torch-xpu-ops/src/ATen/CMakeLists.txt does not track updates in files:

# ATen XPU headers

macro(install_xpu_headers glob_pattern dest_subdir)
  file(GLOB headers ${glob_pattern})
  if(headers)
    install(FILES ${headers} DESTINATION "${AT_INSTALL_INCLUDE_DIR}/${dest_subdir}")
  endif()
endmacro()

install_xpu_headers("xpu/*.h" "ATen/xpu")
install_xpu_headers("native/xpu/*.h" "ATen/native/xpu")
install_xpu_headers("native/xpu/sycl/*.h" "ATen/native/xpu/sycl")
install_xpu_headers("native/xpu/mkl/*.h" "ATen/native/xpu/mkl")
install_xpu_headers("native/nested/xpu/*.h" "ATen/native/nested/xpu")
install_xpu_headers("native/nested/xpu/sycl/*.h" "ATen/native/nested/xpu/sycl")
install_xpu_headers("native/quantized/*.h" "ATen/native/quantized/xpu")
install_xpu_headers("native/quantized/sycl/*.h" "ATen/native/quantized/xpu/sycl")
install_xpu_headers("native/sparse/xpu/*.h" "ATen/native/sparse/xpu")
install_xpu_headers("native/sparse/xpu/sycl/*.h" "ATen/native/sparse/xpu/sycl")
install_xpu_headers("native/transformers/*.h" "ATen/native/transformers/xpu")
install_xpu_headers("native/transformers/sycl/*.h" "ATen/native/transformers/xpu/sycl")

[Silv3S]

Thanks Paweł, it works. Problem is only visible in incremental builds and this PR didn't break anything. Sorry for the false alarm