// constant zero.
// `ConcreteOpType` must be an concrete MLIR op class that has an optional
// bias operand named 'bias'.
template <typename ConcreteOpType>
struct RemoveOptionalZeroBias : public OpRewritePattern<ConcreteOpType> {
  using OpRewritePattern<ConcreteOpType>::OpRewritePattern;

  LogicalResult matchAndRewrite(ConcreteOpType op,