// Make sure the filter is a constant or a constant transpose.
    Operation* filter_op = filter.getDefiningOp();
    const bool is_constant = isa_and_nonnull<stablehlo::ConstantOp>(filter_op);
    const bool is_constant_transpose =
        isa_and_nonnull<stablehlo::TransposeOp>(filter_op) &&
        isa_and_nonnull<stablehlo::ConstantOp>(
            filter_op->getOperand(0).getDefiningOp());
    if (!is_constant && !is_constant_transpose) {