Arm backend: Add log1p decomposition

[robell]

• Decompose log1p and mark as supported in TOSA FP profile
• Add log1p operator tests with data around the epsilon value
• Add log1p to table-op LUT mapping for quantized path

Change-Id: I34695a95e76e1291f0ccd52df8b7254260e74240

cc @freddan80 @per @zingo @oscarandersson8218 @digantdesai

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❌ 5 New Failures, 7 Unrelated Failures

As of commit aeaf9d7 with merge base 02682bc ():

NEW FAILURES - The following jobs have failed:

• Apple / build-demo-ios / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 1
• Build Presets / apple (ios-simulator) / build (gh)
  The process '/opt/homebrew/bin/git' failed with exit code 128
• Build Presets / apple (macos) / build (gh)
  The process '/opt/homebrew/bin/git' failed with exit code 128
• pull / unittest-arm-backend-with-no-fvp (test_pytest_models) / linux-job (gh)
  RuntimeError: Command docker exec -t 12cf0ea8209fba8c6ca451bdeef4f5a28df36be062f8764f787936b881d6a49a /exec failed with exit code 1
• trunk / test-arm-backend (test_pytest_models_ethosu_fvp) / linux-job (gh)
  RuntimeError: Command docker exec -t af54496cde0f4aa2c201d6917d4ec2c9b20315b4375ee55e2fba33204289c253 /exec failed with exit code 1

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• trunk / test-coreml-delegate / macos-job (gh) (similar failure)
  The process '/opt/homebrew/bin/git' failed with exit code 128
• trunk / test-huggingface-transformers-macos (distilbert|coreml_fp32_gpu|--quantize) / macos-job (gh) (similar failure)
  The process '/opt/homebrew/bin/git' failed with exit code 128

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Build Presets / apple (ios) / build (gh) (trunk failure)
  The process '/opt/homebrew/bin/git' failed with exit code 128
• Build Presets / apple (llm) / build (gh) (trunk failure)
  The process '/opt/homebrew/bin/git' failed with exit code 128
• trunk / test-huggingface-transformers-macos (bert|coreml_fp32_gpu|--quantize) / macos-job (gh) (trunk failure)
  The process '/opt/homebrew/bin/git' failed with exit code 128
• trunk / test-huggingface-transformers-macos (olmo-1b|coreml_fp32_gpu|--quantize) / macos-job (gh) (trunk failure)
  The process '/opt/homebrew/bin/git' failed with exit code 128

UNSTABLE - The following job is marked as unstable, possibly due to flakiness on trunk:

• pull / android / run-emulator (gh) (#16137)
  Timeout waiting for emulator to boot.

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[Copilot]

Pull request overview

This PR adds support for the log1p operator in the Arm backend by implementing a custom decomposition strategy and marking it as supported in TOSA profiles.

• Implements a hybrid decomposition using a 6-term Taylor polynomial for small inputs (|x| ≤ 1e-3) and falls back to log(1+x) for larger values
• Adds log1p to the quantized operator LUT mapping and TOSA FP/BI profile support lists
• Includes comprehensive test coverage with edge cases around the epsilon threshold

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
backends/arm/test/ops/test_log1p.py	New test file with parametrized tests for FP, INT, and VGF pipelines using epsilon-focused test data
backends/arm/quantizer/quantization_annotator.py	Adds log1p to the list of table-based quantized operators
backends/arm/operator_support/tosa_profile_supported_op_lists.py	Marks log1p as supported in TOSA FP and BI profiles
backends/arm/_passes/insert_table_ops.py	Maps log1p EXIR op to torch implementation for LUT generation
backends/arm/_passes/decompose_log1p_pass.py	New pass implementing the polynomial/log hybrid decomposition
backends/arm/_passes/arm_pass_manager.py	Registers the new decomposition pass in the TOSA pipeline
backends/arm/_passes/init.py	Exports the new DecomposeLog1pPass class

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[zingo]

@robell this got merged but have fails in Arm tests, are they know fails and unrelated? If so can you please add a note about it so other that checked for errors know, and if not do we need to revert?

EDIT: no problem fails are know, see next comment

[zingo]

Checked the error it is knows fail and are unrelated to the PR and hopefully fixed now a few merged later then this was merged. #16335
FAILED backends/arm/test/models/test_T5ForConditionalGeneration_arm.py::test_T5ForConditionalGeneration_tosa_FP
FAILED backends/arm/test/models/test_T5ForConditionalGeneration_arm.py::test_T5ForConditionalGeneration_tosa_INT