[ExecuTorch][WebGPU] slice_copy op test suite (cases.py op-test framework)

[JulianCloudNTH]

Stack from ghstack (oldest at bottom):

• [ExecuTorch][WebGPU] cat op test suite (cases.py op-test framework) #20399
• [ExecuTorch][WebGPU] Add cat op + ValueList graph support (aten.cat.default) #20398
• [ExecuTorch][WebGPU] permute_copy op test suite (cases.py op-test framework) #20397
• [ExecuTorch][WebGPU] Add permute_copy + IntList graph support (aten.permute_copy.default) #20396
• -> [ExecuTorch][WebGPU] slice_copy op test suite (cases.py op-test framework) #20395
• [ExecuTorch][WebGPU] Add slice_copy op (aten.slice_copy.Tensor) #20394
• [ExecuTorch][WebGPU] squeeze_copy + unsqueeze_copy test suites (cases.py op-test framework) #20393
• [ExecuTorch][WebGPU] Add squeeze_copy + unsqueeze_copy (flat copies) #20392
• [ExecuTorch][WebGPU] sigmoid op test suite (cases.py op-test framework) #20391
• [ExecuTorch][WebGPU] Add sigmoid op (aten.sigmoid.default) #20390
• [ExecuTorch][WebGPU] select_copy op test suite (cases.py op-test framework) #20363
• [ExecuTorch][WebGPU] Add select_copy op (aten.select_copy.int) #20362
• [ExecuTorch][WebGPU] view_copy op test suite (cases.py op-test framework) #20361
• [ExecuTorch][WebGPU] Add view_copy op (aten.view_copy.default) #20360
• [ExecuTorch][WebGPU] mul op test suite (cases.py op-test framework) #20359

Registers aten.slice_copy.Tensor in the cases.py op-test framework: a _slice_suite of 4 configs (leading-dim slice [:,1:5], last-dim slice [...,1:3], step-2 [:,0:8:2], negative-end [:,1:-1]) that generate_op_tests exports via VulkanPartitioner and compares to a torch golden on Dawn. Also adds test/ops/slice/test_slice.py (SliceModule + CONFIGS + export-delegation/eager smoke test) and the aten.slice_copy.Tensor partitioner-allowlist entry in tester.py.
@exported-using-ghexport

Differential Revision: D108793151

Differential Revision: D108793151

[pytorch-bot]

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❌ 3 New Failures, 2 Unrelated Failures

As of commit 9a9f212 with merge base 0e65ba6 ():

NEW FAILURES - The following jobs have failed:

• pull / test-llama-runner-qnn-linux (fp32, qnn_16a16w, qnn) / linux-job (gh)
  RuntimeError: Command docker exec -t d3aad592aa4bd25a8c3138820cca606139a47cba6d39576ec04223a85d67b9b1 /exec failed with exit code 137
• pull / unittest / linux / linux-job (gh)
  RuntimeError: Command docker exec -t f6da26c2da31660629f548822829c53fc42b775f133feffef3927c87c73fe11f /exec failed with exit code 1
• pull / unittest-editable / linux / linux-job (gh)
  RuntimeError: Command docker exec -t 9cf80fa3768bf2faa5dc84658e1b11827de1901b4ff5e3d514239292e5e729fb /exec failed with exit code 1

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

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

• pull / unittest / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1
• pull / unittest-editable / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

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[JulianCloudNTH]

@claude review

[claude]

Claude finished @JulianCloudNTH's task in 46s —— View job

---

Code Review: slice_copy op test suite

• Read PR diff against base
• Compare against sibling op-test patterns (select, squeeze)
• Review for correctness & consistency

---

This is a clean, well-scoped addition that follows the established WebGPU op-test conventions closely. test_slice.py mirrors test_select.py almost exactly, and the cases.py / tester.py hooks match the existing view_copy/select registrations. No blocking issues.

Observations

1. test_golden_matches_eager is a tautology — backends/webgpu/test/ops/slice/test_slice.py:71

torch.testing.assert_close(SliceModule(fn)(x), fn(x))

SliceModule.forward just calls self.fn(x), so this compares fn(x) against fn(x) and can never fail. It's effectively a no-op as a correctness check (the real eager-vs-backend comparison happens in generate_op_tests on Dawn). This is consistent with test_select.py:70, so it's a pre-existing pattern rather than a regression — flagging only so it's a conscious choice. The actual signal here is test_export_delegates; the golden check could arguably be dropped, but keeping it for symmetry with select is reasonable.

2. No _op_delegated fallback check (unlike squeeze) — test_squeeze.py:56-73 additionally asserts the op was absorbed into the delegate rather than left as a CPU fallback node. slice/select/view_copy only check that a VulkanBackend delegate exists, which a single delegated node elsewhere in the graph would satisfy even if slice_copy itself fell back. Since these modules are single-op, the risk is low, but adding the _op_delegated(edge, "slice_copy") assertion would make test_export_delegates strictly verify what the PR claims. Optional, and again consistent with the select precedent.

3. Config coverage looks good. Leading-dim, last-dim, step-2, and negative-end cover the interesting slice_copy paths. The step2 case ([:, 0:8:2]) is a nice inclusion since strided slices are a common kernel edge case. One gap worth a thought: a negative-step slice (e.g. [:, ::-1]) — if the Vulkan kernel doesn't support it, it'd be good to know it gracefully falls back rather than mis-lowers, but that's a follow-up concern, not required here.

Nits

• test_slice.py uses _export (returns to_executorch()) while test_squeeze.py uses _lower (returns the edge program, then calls .to_executorch() separately). The _export naming here matches select, so it's fine — just noting the two naming conventions coexist in this directory.
• __init__.py is license-header-only, consistent with the other ops/*/__init__.py.

Verdict: LGTM. The two structural notes (tautological golden check, missing op-fallback assertion) are inherited from the select template, so they're fair to defer; if you'd like the suite to be stricter, point (2) is the highest-value addition.
· gh/JulianCloudNTH/44/head