onnxruntime/js/web/lib/wasm/jsep/webgpu/ops/fuse-utils.ts

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

import {MAX_CLIP, MIN_CLIP} from '../../util';

export interface InternalActivationAttributes {
  readonly activation: string;
  readonly clipMin?: number;
  readonly clipMax?: number;
  readonly activationCacheKey: string;
}

export const getActivationSnippet = (attributes: InternalActivationAttributes, isVec4 = false): {
  activationFunction: string; applyActivation: string;
} => {
  switch (attributes.activation) {
    case 'Relu':
      return {
        activationFunction: '',
        applyActivation: isVec4 ? 'value = max(value, vec4(0.0));' : 'value = max(value, 0.0);'
      };
    case 'Sigmoid':
      return {activationFunction: '', applyActivation: 'value = (1.0 / (1.0 + exp(-value)));'};
    case 'Clip':
      return {
        activationFunction: `const clip_min_=f32(${attributes.clipMin!});const clip_max_=f32(${attributes.clipMax!});`,
        applyActivation: isVec4 ? 'value = clamp(value, vec4(clip_min_), vec4(clip_max_));' :
                                  'value = clamp(value, clip_min_, clip_max_);'
      };
      // TODO: adding other activations that can be fused.
    default:
      return {activationFunction: '', applyActivation: ''};
  }
};

export const parseInternalActivationAttributes =
    (attributes: Record<string, unknown>|undefined): InternalActivationAttributes => {
      const activation = attributes?.activation as string || '';

      if (activation === 'Clip') {
        const [clipMin, clipMax] = attributes?.activation_params as [number, number] || [MIN_CLIP, MAX_CLIP];
        return {activation, clipMax, clipMin, activationCacheKey: `${activation}:${clipMin},${clipMax}`};
      }
      return {activation, activationCacheKey: activation};
    };