| --- |
| library_name: kernels |
| license: apache-2.0 |
| tags: |
| - kernel |
| - webgpu |
| - wgsl |
| --- |
| # ai.onnx.Constant |
|
|
| `ai.onnx` · standard ONNX operator · ONNX opset ≥ 24 |
|
|
| ## Description |
|
|
| Produces a numeric constant from ONNX's tensor-valued `value` attribute or its float scalar/list shorthands. Sparse, string, and int64-only shorthand attributes are unsupported. |
|
|
| See the [ONNX `Constant` spec](https://onnx.ai/onnx/operators/onnx__Constant.html) for the reference semantics. |
|
|
| ## Outputs |
|
|
| | Name | Logical dtype | Rank | Shape | Description | Presence | |
| | --- | --- | --- | --- | --- | --- | |
| | `output` | `T` | — | — | Output tensor containing the constant value(s) specified by the attribute. | required | |
|
|
| ## Attributes |
|
|
| Attributes and default values (overridable per request): |
|
|
| | Attribute | Default | Description | |
| | --- | --- | --- | |
| | `value` | — | Tensor-valued constant represented as `{ dtype, shape, values }`; `dtype` and `shape` must match the output contract and `values` supplies the tensor elements in row-major order. | |
| | `value_float` | — | A single float32 value producing a scalar tensor. | |
| | `value_floats` | — | Float32 values producing a one-dimensional tensor. | |
|
|
| ## Type constraints |
|
|
| | Variable | Allowed dtypes | |
| | --- | --- | |
| | `T` | `float32`, `float16`, `int32`, `int16`, `uint32`, `int8`, `uint8`, `bool` | |
|
|
| ## Files |
|
|
| - [`metadata.json`](build/webgpu/metadata.json) — kernel metadata (id, digests, per-variant templates, provenance) |
| - [`manifest.json`](build/webgpu/manifest.json) — the op contract (source of truth) |
| - [`test.json`](build/webgpu/test.json) — correctness cases |
| - [`bench.json`](build/webgpu/bench.json) — benchmark cases |
| - [`constant.wgsl.jinja`](build/webgpu/constant.wgsl.jinja) |
|
|
| ## Use with `@huggingface/kernels` |
|
|
| ```sh |
| npm install --save-exact @huggingface/kernels@0.0.1-preview.3 |
| ``` |
|
|
| Outputs with inferable metadata are allocated automatically. Explicit `outputs` entries request optional results or provide metadata that cannot be inferred from the supplied inputs and attributes. |
|
|
| This example supplies explicit metadata for: |
|
|
| - `output` |
|
|
| The `version: 1` option selects the published kernel contract; it is independent of any operator opset, contrib `since_version`, or model version. |
| It follows the `v1` branch as fixes land. To pin exact artifact bytes, pass a 40-character commit `revision` instead of `version`. |
|
|
| ```js |
| import { getKernel } from "@huggingface/kernels"; |
| |
| const kernel = await getKernel("webgpu-kernels/ai.onnx.Constant", { version: 1 }); |
| // Explicit destinations request optional results or supply metadata that cannot be inferred. |
| const { output } = await kernel({}, { |
| attrs: { value_float: -2.5 }, |
| outputs: { output: { shape: [], dtype: "float32" } }, |
| }); |
| ``` |
|
|
