EVOLUTION-MANAGER

Edit File: resource_operation_safety_analysis.h

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#ifndef TENSORFLOW_COMPILER_JIT_RESOURCE_OPERATION_SAFETY_ANALYSIS_H_
#define TENSORFLOW_COMPILER_JIT_RESOURCE_OPERATION_SAFETY_ANALYSIS_H_

#include "tensorflow/compiler/jit/graphcycles/graphcycles.h"
#include "tensorflow/core/framework/function.h"
#include "tensorflow/core/graph/graph.h"

namespace tensorflow {
// An XLA cluster hoists all resource reads to be beginning of the cluster
// execution and all the resource writes to the end.  This means it cannot
// enforce arbitrary ordering dependencies (via control or data edges) between
// resource operations.  Since all resource reads happen before all resource
// writes, edges constraining resource writes to happen before resource reads
// are problematic.  This analysis returns the set of pairs of resource
// operations that cannot be put in the same cluster because XLA cannot respect
// the dependencies between them in the TensorFlow program.
//
// The restrictions are not transitive: it is fine to put A and C in the same
// cluster even if the returned set contains (A,B) and (B,C).
//
// In other words, if these pairs are seen as edges in an undirected graph of
// the nodes in `g` then auto-clustering is at least as constrained as the graph
// coloring problem on this graph.
//
//
// For instance if we auto-cluster all operations in this TensorFlow graph:
//
//         AssignVariablepOp0  ->  AssignVariableOp1
//                                      |
//                                      v
//                              ReadVariableOp0  ->  ReadVariableOp1
//
// we will lose the AssignVariablepOp1 -> ReadVariableOp0. The ReadVariableOp0
// -> ReadVariableOp1 and AssignVariableOp0 -> AssignVariableOp1 edges will be
// respected by XlaLaunchOp though because all reads happen before all writes
// with that limited clustering..
//
//
// NB!  The result computed by this analysis assumes that we don't auto-cluster
// back-edges (i.e. the edges from NextIteration to Merge).
//
// NB!  The result computed by this analysis assumes that we don't auto-cluster
// functional control flow nodes containing resource operations.
//
// If `resource_ops_to_ignore` is set then nodes for which it returns true are
// ignored (we pretend these nodes are not resource operations).
Status ComputeIncompatibleResourceOperationPairs(
    const Graph& g, const FunctionLibraryDefinition* flib_def,
    const std::function<Status(const Node&, bool*)>& resource_ops_to_ignore,
    std::vector<std::pair<int, int>>* result);
}  // namespace tensorflow

#endif  // TENSORFLOW_COMPILER_JIT_RESOURCE_OPERATION_SAFETY_ANALYSIS_H_