Arm backend: Improve ELU support

[AdrianLundell]

Arm backend: Improve ELU support

• Adds support for different scale and input_scale values
• Adds support for related SELU and CELU operators, corresponding
  to ELU with particular scales.
• Use initial float values for alpha, scale and input_scale
  rather than rounded values.

[pytorch-bot]

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  backends/xnnpack/test/ops/test_conv2d.py::TestConv2d::test_fp16_conv2d

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[Copilot]

Pull request overview

This PR extends Arm backend handling of the ELU-family activations by adding explicit support for SELU and CELU through conversion/decomposition passes, updating operator support/partitioning metadata, and expanding the ELU test suite accordingly.

Changes:

• Add pass to convert SELU/CELU to parameterized ELU, and update ELU decomposition to respect alpha/scale/input_scale.
• Extend quantization annotation and TOSA operator support lists to include selu/celu, and adjust partitioner “do-not-decompose” policy for float.
• Refactor/expand ELU tests to cover ELU parameters as well as nn.SELU and nn.CELU, and update related docs.

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
backends/arm/tosa/partitioner.py	Prevents decomposition of selu/celu in FP flows so backend passes can handle them.
backends/arm/test/ops/test_elu.py	Refactors test structure and adds SELU/CELU + additional ELU parameter coverage across pipelines.
backends/arm/scripts/docgen/vgf/vgf-getting-started-tutorial.md.in	Clarifies compiler script positioning (quick tests vs production API).
backends/arm/scripts/docgen/ethos-u/ethos-u-getting-started-tutorial.md.in	Same documentation clarification as VGF tutorial.
backends/arm/quantizer/quantization_annotator.py	Adds selu/celu to one-to-one quantization annotation set.
backends/arm/operator_support/tosa_profile_supported_op_lists.py	Declares selu/celu as supported ops in relevant TOSA profiles.
backends/arm/_passes/insert_table_ops.py	Updates ELU table-op computation to use stored float params; adds SELU/CELU to special set.
backends/arm/_passes/decompose_elu_pass.py	Adds ELU-family conversion pass and extends ELU decomposition to handle SELU/CELU + extra params.
backends/arm/_passes/convert_elu_params.py	Adjusts quantized ELU parameter handling to avoid int8 kernel crashes while preserving float params via metadata.
backends/arm/_passes/arm_pass_manager.py	Inserts the new ELU-family conversion pass into both backend and annotation pipelines.
backends/arm/_passes/init.py	Exposes the new ConvertEluFamilyToEluPass for pipeline construction.

Comments suppressed due to low confidence (1)

backends/arm/_passes/decompose_elu_pass.py:33

• get_elu_decomposition’s docstring still describes the old ELU rewrite (and doesn’t mention scale/input_scale or expm1). Please update the docstring so it matches the implementation and the updated decomposition used in DecomposeEluPass.

def get_elu_decomposition(op) -> tuple:
    """Returns the decomposition of the given aten.elu operation into its
    equivalent TOSA-supported operations.

    This handles both edge dialect ops and core PyTorch ops. The decomposition strategy
    is:
        elu(x, y) → where(greater_or_eq(x, 0), (exp(x)-1), x)

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[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

backends/arm/_passes/decompose_elu_pass.py:33

• The get_elu_decomposition() docstring no longer matches the implementation: it claims to handle core PyTorch ops, and the decomposition formula shown is outdated (it omits scale/input_scale and uses a different branch ordering). Please update the docstring to reflect the current supported ops and decomposition used by DecomposeEluPass.

def get_elu_decomposition(op) -> tuple:
    """Returns the decomposition of the given aten.elu operation into its
    equivalent TOSA-supported operations.

    This handles both edge dialect ops and core PyTorch ops. The decomposition strategy
    is:
        elu(x, y) → where(greater_or_eq(x, 0), (exp(x)-1), x)

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated no new comments.