slyubomirsky commented on code in PR #15689: URL: https://github.com/apache/tvm/pull/15689#discussion_r1408648544
########## include/tvm/relax/dataflow_analysis.h: ########## @@ -0,0 +1,198 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +/*! + * \file tvm/relax/dataflow_analysis.h + * \brief A reusable framework for dataflow analysis in Relax. + * Based on Adrian Sampson's course material: + * https://www.cs.cornell.edu/courses/cs6120/2020fa/lesson/4/ + * Do not confuse with dataflow pattern matching (does not use this machinery) + */ + +#ifndef TVM_RELAX_DATAFLOW_ANALYSIS_H_ +#define TVM_RELAX_DATAFLOW_ANALYSIS_H_ + +#include <tvm/relax/analysis.h> +#include <tvm/relax/expr.h> +#include <tvm/runtime/object.h> + +#include <utility> + +namespace tvm { +namespace relax { + +/*! \brief For dataflow analysis, we need to have a control flow graph. + * We will organize this graphs by bindings, which allows analyses to + * state their results for each binding in a SeqExpr. + * + * There are a few cases that have to be handled: + * 1. A normal binding (most common)ICHECK + * 2. The condition expression in an If node (a "split" point) + * 3. A merge point (the variable to which an If node is bound: it is a "merge" between + * the SeqExprs in the true and false branches) + * 4. The body expression in a SeqExpr (not actually bound) + */ +enum BindingNodeKind : int { kBinding = 0, kIfCond = 1, kIfMerge = 2, kSeqBody = 3 }; + +class GraphBindingNode : public Object { + public: + /*! \brief The SeqExpr the binding resides in. */ + SeqExpr seq; + + /*! \brief The arguments to the binding. Only the first binding in the graph has arguments + * (i.e., the function arguments). */ + Array<Var> args; + + /*! \brief Index of the binding block in the SeqExpr where the binding is found. + * Convention: We put the SeqExpr body at one block past the final block. */ + size_t block_idx; + + /*! \brief Index of the binding within the binding block corresponding to this binding. + * Convention: Both the If condition and merge are mapped to the same index. + * We use the kind to distinguish. */ + size_t binding_idx; + + /*! \brief The kind of binding this is. */ + BindingNodeKind kind; + + void VisitAttrs(tvm::AttrVisitor* v) { + v->Visit("seq", &seq); + v->Visit("args", &args); + v->Visit("block_idx", &block_idx); + v->Visit("binding_idx", &binding_idx); + v->Visit("kind", &kind); + } + + static constexpr const uint32_t _type_index = TypeIndex::kDynamic; + static constexpr const char* _type_key = "relax.analysis.GraphBinding"; + TVM_DECLARE_BASE_OBJECT_INFO(GraphBindingNode, Object); +}; + +/*! \brief Representation of a binding in the control flow graph */ +class GraphBinding : public ObjectRef { + public: + /*! + * \brief Create a GraphBinding. See the docs on GraphBindingNode for further details. + * + * \param seq: The SeqExpr in which the binding resides. + * \param args: The arguments to the binding (only nonempty for the first binding: + * these will be the function arguments) + * \param block_idx: The index of the BindingBlock in the SeqExpr + * where the binding resides (for the return expression, use one past the final block). + * \param binding_idx: The index of the binding in the BindingBlock corresponding to the binding. + * \param kind: The kind of binding this is. (Used especially to distinguish If node conditions + * from the merge after the If) + */ + TVM_DLL static GraphBinding Create(const SeqExpr& seq, const Array<Var>& args, size_t block_idx, + size_t binding_idx, BindingNodeKind kind); + + TVM_DEFINE_NOTNULLABLE_OBJECT_REF_METHODS(GraphBinding, ObjectRef, GraphBindingNode); +}; + +/* A control flow graph corresponding to a function. + */ +class ControlFlowGraphNode : public Object { + public: + /*! \brief The bindings in the graph. 0 is the entry point. */ + Array<GraphBinding> bindings; + /*! \brief The ith member is the list of predecessors (indices) to binding i in bindings. */ + Array<Array<Integer>> preds; Review Comment: I'll see if there might be a better way to set up the data structures. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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