Function MGB_IMPL_OPR_GRAD

src/opr/impl/cond.cpp:805–828

#if MGB_ENABLE_GRAD
MGB_IMPL_OPR_GRAD(CondExecMark) {
    if (wrt_idx == opr.input().size() - 1 || !out_grad.at(wrt_idx)) {
        return nullptr;
    }
    using GradMode = CondExecMark::Param::GradMode;
    using MergeMode = CondExecMerge::Param::Mode;
    MergeMode grad_mode;
    SymbolVarArray grad_shapes;
    switch (opr.param().grad_mode) {
        case GradMode::SUM:
            grad_mode = MergeMode::SUM;
            grad_shapes.emplace_back(SymbolVar{opr.input(wrt_idx)}.symshape());
            break;
        case GradMode::SUM_COND_OUT:
            grad_mode = MergeMode::SUM_COND_OUT;
            break;
        default:
            mgb_throw(MegBrainError, "invalid grad_mode");
    }
    return CondExecMerge::make_opr(
                   {out_grad[wrt_idx]}, grad_shapes, {1, grad_mode},
                   OperatorNodeConfig{})
            ->output(0);
}
#endif

/* ============================= CondExecMerge ============================= */