[torchlib] Add missing dtype parameter to aten_mean_dim - #2885
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Justin Chu (justinchuby) merged 2 commits intoApr 10, 2026
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The ATen schema for mean.dim documents dtype as an optional parameter, but aten_mean_dim and aten_mean_dim_complex did not accept it. This causes a TypeError when PyTorch lowers mean.dim with an explicit dtype (e.g. from GlobalAveragePooling2D in Keras). Add dtype: int = -1 to both functions, following the same pattern used by aten_sum_dim_IntList. Fixes microsoft#2884
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Hey! This is my first contribution to onnxscript. We ran into this while exporting Keras models to ONNX at work - GlobalAveragePooling2D lowers through aten::mean.dim with an explicit dtype, which hits the missing parameter. Happy to adjust anything if needed😄 |
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #2885 +/- ##
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- Coverage 72.04% 72.03% -0.01%
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Files 239 239
Lines 29305 29309 +4
Branches 2880 2882 +2
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- Misses 7216 7218 +2
- Partials 977 979 +2 ☔ View full report in Codecov by Sentry. |
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Linus Juni (@linusjuni) could you fix lint? |
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@microsoft-github-policy-service agree |
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Fixes #2884 `aten_mean_dim` and `aten_mean_dim_complex` are missing the `dtype` keyword argument from their signatures, even though the ATen schema documents it (`ScalarType? dtype=None`). This causes a `TypeError` when PyTorch lowers `aten::mean.dim` with an explicit `dtype` - which happens for any model using `GlobalAveragePooling2D` (Keras/PyTorch). - Add `dtype: int = -1` to `aten_mean_dim`, with `op.Cast` when dtype is specified - Add `dtype: int = -1` to `aten_mean_dim_complex`, raising `NotImplementedError` for complex tensors Follows the same pattern used by `aten_sum_dim_IntList` and `aten_sum_dim_IntList_complex`.
Justin Chu (justinchuby)
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) # Honor the dtype argument of aten::mean when exporting without dim Fixes #3008 ## Summary The no dim overload of `aten::mean` declares `dtype` in its schema (`mean(Tensor self, *, ScalarType? dtype=None)`), but `aten_mean` in `onnxscript/function_libs/torch_lib/ops/core.py` did not accept the argument. Exporting `torch.mean(x, dtype=torch.float64)` for a float32 input succeeded silently, emitted only `ReduceMean -> Squeeze`, declared a FLOAT output, and accumulated in float32. For the input `[[1e8, 1.0, -1e8]]` PyTorch returns `0.3333333333333333` as float64 while the exported model returned `0.0` as float32. ## Changes - `aten_mean` is now `trace_only=True`, takes `dtype: int = -1`, and when a dtype is given casts `self` before `ReduceMean`. The no dtype path is unchanged (`ReduceMean -> Squeeze`). - `aten_mean_complex` takes the same argument and raises `NotImplementedError` when it is supplied, matching `aten_mean_dim_complex` and `aten_sum_complex`. - New `ops.aten.mean.dtype` OpInfo in `tests/function_libs/torch_lib/extra_opinfo.py` (`sample_inputs_mean_dtype`) registered against `core_ops.aten_mean` in `ops_test_data.py`. It yields `make_tensor` samples of shapes `(5, 5)`, `(5,)` and `()` plus the precision sensitive tensor `[[1e8, 1.0, -1e8]]`, all with `dtype=torch.float64`. ## Why the cast happens before the reduction `aten_mean_dim` (#2885) and `aten_sum` cast the reduced result after the reduction. That is not sufficient here: PyTorch accumulates in the requested dtype, so for `[1e8, 1.0, -1e8]` the float32 mean is `0.0` (the `1.0` is lost when added to `1e8`) while the float64 mean is `1/3`. Casting after `ReduceMean` would produce a DOUBLE tensor holding `0.0`, which still mismatches PyTorch. Casting the input first reproduces PyTorch semantics. The new test includes this sample specifically so that a cast after reduction implementation cannot pass by accident. ## Verification Reporter's script (`torch.onnx.export(..., dynamo=True)` of `torch.mean(x, dtype=torch.float64)` with float32 input) on pristine main at a39c0a5: ``` torch eager result: 0.3333333333333333 dtype: torch.float64 ONNX output elem_type: 1 (FLOAT), expected 11 (DOUBLE) ORT result: 0.0 dtype: float32 ``` With this change: ``` torch eager result: 0.3333333333333333 dtype: torch.float64 ONNX output elem_type: 11 (DOUBLE) ORT result: 0.3333333333333333 dtype: float64 ``` `pytest tests/function_libs/torch_lib/ops_test.py -k mean`: | State | Result | | --- | --- | | Pristine main, without the new test | 8 passed, 48 skipped, 8 xfailed, 60 subtests passed | | New test with the source change stashed | 4 failed, 10 passed, 48 skipped, 8 xfailed, 60 subtests passed. All four `ops_aten_mean_dtype` samples fail with `TypeInferenceError: Inferred elem type differs from existing elem type: (1) vs (11)` | | New test with a cast placed after the reduction | 1 failed, 8 passed, 50 skipped, 8 xfailed, 63 subtests passed. Only the `[[1e8, 1.0, -1e8]]` sample fails: `Expected 0.3333333333333333 but got 0.0` | | New test with this change | 8 passed, 50 skipped, 8 xfailed, 64 subtests passed | The two additional skips in the fixed state are the function proto validity checks, which skip for traced functions. `ruff check` and `ruff format --check` (ruff 0.15.1, the lintrunner pinned version) pass on the three changed files. Environment: Python 3.10, torch 2.13.0 (CPU), onnx 1.22.0, onnxruntime 1.23.2, macOS arm64.
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Fixes #2884
aten_mean_dimandaten_mean_dim_complexare missing thedtypekeyword argument from their signatures, even though the ATen schema documents it (ScalarType? dtype=None). This causes aTypeErrorwhen PyTorch lowersaten::mean.dimwith an explicitdtype- which happens for any model usingGlobalAveragePooling2D(Keras/PyTorch).dtype: int = -1toaten_mean_dim, withop.Castwhen dtype is specifieddtype: int = -1toaten_mean_dim_complex, raisingNotImplementedErrorfor complex tensorsFollows the same pattern used by
aten_sum_dim_IntListandaten_sum_dim_IntList_complex.