Class GatherProgram

tfjs-backend-webgpu/src/gather_webgpu.ts:21–55

import {computeDispatch, flatDispatchLayout} from './webgpu_util';

export class GatherProgram implements WebGPUProgram {
  outputShape: number[];
  shaderKey: string;
  dispatchLayout: {x: number[]};
  dispatch: [number, number, number];
  variableNames: string[] = ['A', 'indices'];
  workgroupSize: [number, number, number] = [64, 1, 1];
  aShape: number[];
  size = true;

  constructor(aShape: number[], outputShape: number[]) {
    this.outputShape = aShape.slice();
    this.aShape = aShape;
    this.outputShape = outputShape;
    this.dispatchLayout = flatDispatchLayout(this.outputShape);
    this.dispatch = computeDispatch(
        this.dispatchLayout, this.outputShape, this.workgroupSize);
    this.shaderKey = `gather`;
  }

  getUserCode(): string {
    const sourceCoords = getSourceCoords(this.aShape);
    const userCode = `
      ${main('index')} {
        if (index < uniforms.size) {
          let resRC = getCoordsFromIndex(index);
          let indexZ = i32(getIndices(resRC.x, resRC.z));
          let inBounds = select(0.0, 1.0, indexZ >= 0 && indexZ < uniforms.aShape[2]);
          setOutputAtIndex(index, inBounds * getA(${sourceCoords}));
        }
      }
    `;
    return userCode;
  }
}

// The input and output are always flattened into rank 4 tensors.
function getSourceCoords(aShape: number[]): string {