File size: 2,985 Bytes
5205f7a b1ec92f 5205f7a b1ec92f 5205f7a b1ec92f | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | ---
library_name: kernels
license: apache-2.0
tags:
- kernel
- webgpu
- wgsl
---
# ai.onnx.If
`ai.onnx` · internal tensor lowering (non-standard) · reviewed against ONNX opset 25
## Description
Support status: the standard ONNX `If` control-flow operator is not implemented because standalone kernel packages cannot carry or execute its `then_branch` and `else_branch` graph attributes. This internal lowering only selects elementwise between two pre-evaluated, equal-sized tensors from a scalar condition and must not be treated as ONNX `If`.
See the [standard ONNX `If` spec](https://onnx.ai/onnx/operators/onnx__If.html) for the contract this internal lowering does not implement.
## Inputs
| Name | Bind key | Logical dtype | Rank | Shape | Description | Presence |
| --- | --- | --- | --- | --- | --- | --- |
| `cond` | `cond` | `B` | — | — | Scalar boolean condition that selects which value tensor to output. | required |
| `then_value` | `then_value` | `T` | — | — | Values to output when `cond` is true. | required |
| `else_value` | `else_value` | `T` | — | — | Values to output when `cond` is false. | required |
## Outputs
| Name | Bind key | Logical dtype | Rank | Shape | Description | Presence |
| --- | --- | --- | --- | --- | --- | --- |
| `y` | `y` | `T` | — | — | Output tensor with the same number of elements as `then_value` and `else_value`. | required |
## Type constraints
| Variable | Allowed dtypes |
| --- | --- |
| `T` | `float32` |
| `B` | `uint32`, `bool` |
## Files
- [`metadata.json`](build/webgpu/metadata.json) — kernel metadata (id, digests, 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 + tuning cases
- [`if-select.wgsl.jinja`](build/webgpu/if-select.wgsl.jinja)
## Use with `@huggingface/kernels`
The loader automatically allocates outputs whose metadata it can derive from the manifest contract and this call.
The explicit `outputs` entries provide shape and logical dtype metadata for the results listed below:
- `y`
Each entry either requests an optional result or supplies metadata that cannot be inferred from the inputs.
The `version: 1` option selects the published kernel contract; it is independent of any operator opset, contrib `since_version`, or model version.
Replace each `*Data` placeholder with a typed array containing the corresponding input data.
```js
import { getKernel } from "@huggingface/kernels";
const kernel = await getKernel("webgpu-kernels/ai.onnx.If", { version: 1 });
// Explicit destinations request optional results or supply metadata that cannot be inferred.
const { y } = await kernel({
cond: { data: condData, shape: [1] },
then_value: { data: then_valueData, shape: [1] },
else_value: { data: else_valueData, shape: [1] },
}, {
outputs: { y: { shape: [1], dtype: "float32" } },
});
```
|