Method clone

tfjs-core/src/engine.ts:505–524

* This method is called instead of the public-facing tensor.clone() when * saving a tensor for backwards pass. It makes sure to add the clone * operation to the tape regardless of being called inside a kernel * execution.

(x: Tensor)

   * execution.
   */
  private clone(x: Tensor): Tensor {
    const y: Tensor = ENGINE.runKernel(Identity,
                                       {x} as unknown as NamedTensorMap);
    const inputs = {x};
    const grad = (dy: Tensor) => ({
      x: () => {
        const dtype = 'float32';
        const gradInputs = {x: dy};
        const attrs = {dtype};

        return ENGINE.runKernel(
                   Cast, gradInputs as unknown as NamedTensorMap,
                   // tslint:disable-next-line: no-unnecessary-type-assertion
                   attrs as unknown as NamedAttrMap) as Tensor;
      }
    });
    const saved: Tensor[] = [];
    this.addTapeNode(this.state.activeScope.name, inputs, [y], grad, saved, {});
    return y;
  }

  /**
   * Execute a kernel with the given name and return the output tensor.