wehub-resource-sync
100 lines
3.2 KiB
C++
100 lines
3.2 KiB
C++
// Copyright (c) 2023 CINN Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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#include <glog/logging.h>
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#include <functional>
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#include <list>
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#include <queue>
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#include <unordered_map>
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#include <unordered_set>
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#include <vector>
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#include "paddle/cinn/common/dfs_walker.h"
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#include "paddle/common/enforce.h"
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namespace cinn {
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namespace common {
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// strong connected components visitor
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template <typename NodeType>
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class SccWalker final {
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public:
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SccWalker(const SccWalker&) = delete;
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SccWalker(SccWalker&&) = delete;
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using NodeHandlerType = std::function<void(NodeType)>;
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using NodesVisitorType =
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std::function<void(NodeType, const NodeHandlerType&)>;
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SccWalker(const NodesVisitorType& VisitPrevNodes,
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const NodesVisitorType& VisitNextNodes)
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: VisitPrevNodes_(VisitPrevNodes), VisitNextNodes_(VisitNextNodes) {}
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using SccHandlerType = std::function<void(const std::vector<NodeType>&)>;
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// https://en.wikipedia.org/wiki/Kosaraju%27s_algorithm
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template <typename NodeIt>
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void operator()(NodeIt begin,
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NodeIt end,
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const SccHandlerType& SccHandler) const {
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const std::list<NodeType>& dfs_ordered_nodes = [&]() {
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std::list<NodeType> dfs_ordered_nodes;
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DfsVisitor<NodeType> visitor(VisitNextNodes_);
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visitor(
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begin,
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end,
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/*on push*/ [](NodeType) {},
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/*on pop*/
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[&](NodeType node) { dfs_ordered_nodes.push_front(node); });
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return dfs_ordered_nodes;
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}();
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std::unordered_map<NodeType, NodeType> node2root;
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const auto& VisitPrevNode = [&](NodeType node,
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const NodeHandlerType& NodeHandler) {
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VisitPrevNodes_(node, [&](NodeType prev_node) {
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if (node2root.count(prev_node) == 0) {
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NodeHandler(prev_node);
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}
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});
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};
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for (NodeType root : dfs_ordered_nodes) {
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if (node2root.count(root) > 0) {
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continue;
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}
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std::vector<NodeType> scc;
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// Use node2root immutably inside dfs visitor.
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DfsVisitor<NodeType> visitor(VisitPrevNode);
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visitor(root, [&](NodeType node) { scc.push_back(node); });
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SccHandler(scc);
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// Update node2root outside dfs visitor.
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for (NodeType node : scc) {
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PADDLE_ENFORCE_EQ(node2root.emplace(node, root).second,
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true,
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::common::errors::AlreadyExists(
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"Failed to insert the node into node2root. The "
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"node may already exist."));
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}
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}
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}
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private:
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NodesVisitorType VisitPrevNodes_;
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NodesVisitorType VisitNextNodes_;
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};
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} // namespace common
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} // namespace cinn
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