| --- |
| library_name: kernels |
| license: apache-2.0 |
| tags: |
| - kernel |
| - webgpu |
| - wgsl |
| --- |
| # com.microsoft.GemmaRotaryEmbedding |
|
|
| `com.microsoft` · ONNX Runtime contrib operator · contrib since_version 1 |
| |
| ## Description |
| |
| Fuses the Gemma rotary-embedding tail: computes `sin` and `cos` from float32 `emb`, casts them to float16, then evaluates `q * cos + q_rot * sin` and the corresponding expression for `k`. `emb` has shape `(batch, seq, dim)` and is broadcast over the head axis of the `(batch, heads, seq, dim)` operands. Each product is rounded to float16 before the addition. |
|
|
| See the [ONNX Runtime `GemmaRotaryEmbedding` contrib-operator spec](https://github.com/microsoft/onnxruntime/blob/main/docs/ContribOperators.md#com.microsoft.GemmaRotaryEmbedding) for the reference semantics. |
|
|
| ## Inputs |
|
|
| | Name | Upstream name | Logical dtype | WebGPU storage | Rank | Shape | Description | Presence | |
| | --- | --- | --- | --- | --- | --- | --- | --- | |
| | `embT` | `emb` | `U` | `float32` | `3` | — | Rotary angles with shape `(batch_size, seq_len, dim)`, shared by every head. | required | |
| | `qT` | `q` | `T` | same as logical dtype | `4` | — | Query state with shape `(batch_size, num_heads, seq_len, dim)`. | required | |
| | `qRotT` | `q_rot` | `T` | same as logical dtype | `4` | — | Half-rotated query state, same shape as `q`. | required | |
| | `kT` | `k` | `T` | same as logical dtype | `4` | — | Key state, same shape as `q`. | required | |
| | `kRotT` | `k_rot` | `T` | same as logical dtype | `4` | — | Half-rotated key state, same shape as `q`. | required | |
|
|
| ## Outputs |
|
|
| | Name | Upstream name | Logical dtype | Rank | Shape | Description | Presence | |
| | --- | --- | --- | --- | --- | --- | --- | |
| | `output1T` | `output1` | `T` | same as `qT` | same as `qT` | Rotary-embedded query, same shape as `q`. | required | |
| | `output2T` | `output2` | `T` | same as `qT` | same as `qT` | Rotary-embedded key, same shape as `q`. | required | |
|
|
| ## Type constraints |
|
|
| | Variable | Allowed dtypes | |
| | --- | --- | |
| | `T` | `float16` | |
| | `U` | `float32` | |
|
|
| ## Implementation variants |
|
|
| One implementation is selected per call from the device capabilities, the request shapes and the dtypes; these notes say what each one covers. |
|
|
| - `elementwise` — Elementwise rotation. Streams `vec4` words when each head's `(seq, dim)` plane holds a multiple of four elements, so no word straddles two heads; scalar elements otherwise. |
|
|
| ## Device requirements |
|
|
| Every implementation variant requires `shader-f16`; the package has no variant-level fallback without that capability. |
|
|
| ## 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 |
| - [`gemma-rotary-embedding.wgsl.jinja`](build/webgpu/gemma-rotary-embedding.wgsl.jinja) |
|
|
| ## Use with `@huggingface/kernels` |
|
|
| ```sh |
| npm install --save-exact @huggingface/kernels@0.0.1-preview.3 |
| ``` |
|
|
| Required output shapes and logical data types are inferred from the supplied inputs and attributes; result tensors are allocated automatically. |
|
|
| 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`. |
|
|
| 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/com.microsoft.GemmaRotaryEmbedding", { version: 1 }); |
| const { output1T, output2T } = await kernel({ |
| embT: { data: embTData, shape: [1, 2, 4] }, |
| qT: { data: qTData, shape: [1, 1, 2, 4] }, |
| qRotT: { data: qRotTData, shape: [1, 1, 2, 4] }, |
| kT: { data: kTData, shape: [1, 1, 2, 4] }, |
| kRotT: { data: kRotTData, shape: [1, 1, 2, 4] }, |
| }); |
| ``` |
|
|
