Function ggml_visit_parents_graph

subprojects/llama.cpp/ggml/src/ggml.c:6729–6795

}

static size_t ggml_visit_parents_graph(struct ggml_cgraph * cgraph, struct ggml_tensor * node, bool compute) {
    if (node->op != GGML_OP_NONE && compute) {
        node->flags |= GGML_TENSOR_FLAG_COMPUTE;
    }

    const size_t node_hash_pos = ggml_hash_find(&cgraph->visited_hash_set, node);
    GGML_ASSERT(node_hash_pos != GGML_HASHSET_FULL);

    if (ggml_bitset_get(cgraph->visited_hash_set.used, node_hash_pos)) {
        // already visited

        if (compute) {
            // update the compute flag regardless
            for (int i = 0; i < GGML_MAX_SRC; ++i) {
                struct ggml_tensor * src = node->src[i];
                if (src && ((src->flags & GGML_TENSOR_FLAG_COMPUTE) == 0)) {
                    ggml_visit_parents_graph(cgraph, src, true);
                }
            }
        }

        return node_hash_pos;
    }

    // This is the first time we see this node in the current graph.
    cgraph->visited_hash_set.keys[node_hash_pos] = node;
    ggml_bitset_set(cgraph->visited_hash_set.used, node_hash_pos);
    cgraph->use_counts[node_hash_pos] = 0;

    for (int i = 0; i < GGML_MAX_SRC; ++i) {
        const int k =
            (cgraph->order == GGML_CGRAPH_EVAL_ORDER_LEFT_TO_RIGHT) ? i :
            (cgraph->order == GGML_CGRAPH_EVAL_ORDER_RIGHT_TO_LEFT) ? (GGML_MAX_SRC-1-i) :
            /* unknown order, just fall back to using i */ i;

        struct ggml_tensor * src = node->src[k];
        if (src) {
            const size_t src_hash_pos = ggml_visit_parents_graph(cgraph, src, compute);

            // Update the use count for this operand.
            cgraph->use_counts[src_hash_pos]++;
        }
    }

    if (node->op == GGML_OP_NONE && !(node->flags & GGML_TENSOR_FLAG_PARAM)) {
        // reached a leaf node, not part of the gradient graph (e.g. a constant)
        GGML_ASSERT(cgraph->n_leafs < cgraph->size);

        if (strlen(node->name) == 0) {
            ggml_format_name(node, "leaf_%d", cgraph->n_leafs);
        }

        cgraph->leafs[cgraph->n_leafs] = node;
        cgraph->n_leafs++;
    } else {
        GGML_ASSERT(cgraph->n_nodes < cgraph->size);

        if (strlen(node->name) == 0) {