message: Add a comment describing relationship between output features and feature group counts in shape inference.
diff: @@ -1742,7 +1742,14 @@ ShapeInference::InferDegenerateDimensionBroadcastShape(HloOpcode operation,
  ShapeUtil::HumanString(lhs), ShapeUtil::HumanString(rhs),
  dnums.DebugString());
  }
  +
  if (kernel_output_features % feature_group_count > 0) {
  + // A depthwise/grouped filter has the shape
  + // [space0, .. spaceN, GROUP_SIZE, NUM_OUTPUT_FEATURES]. When
  + // [space0, .. spaceN, GROUP_SIZE] is convolved with the input, a shape
  + // [space0, .. spaceN, feature_group_count] is formed. Therefore, the output
  + // feature count (which is equal to kernel output features) has to be a
  + // multiple of feature_group_count.
  return InvalidArgument(
  "Expected output feature dimension (value %d) to be divisible by "
  "feature_group_count (value %d); "
  