EVOLUTION-MANAGER

Edit File: extract_outside_compilation_pass.h

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==============================================================================*/

#ifndef TENSORFLOW_COMPILER_JIT_EXTRACT_OUTSIDE_COMPILATION_PASS_H_
#define TENSORFLOW_COMPILER_JIT_EXTRACT_OUTSIDE_COMPILATION_PASS_H_

#include "absl/types/optional.h"
#include "tensorflow/compiler/jit/encapsulate_util.h"
#include "tensorflow/compiler/xla/status_macros.h"
#include "tensorflow/core/graph/graph.h"

namespace tensorflow {

// Rewrite function for outside compilation subgraphs. It will perform the
// following steps:
//
// 1. Add a XLA computation key placeholder node (it will be used as input for
//    XlaRecvAtHost and XlaSendFromHost);
// 2. Replace all _Arg nodes with one single XlaRecvAtHost node;
// 3. Replace all _Retval nodes with one single XlaSendFromHost node;
// 4. Mark all nodes except key placeholder with attr `xla_cluster_attr_name`
//    and `outside_compilation_attr_name`;
// 5. For nodes marked with attr kXlaConnectedToXlaComputationAttrName, add a
//    control edge from the node to XlaSendFromHost; for nodes marked with attr
//    kXlaConnectedFromXlaComputationAttrName, add a control edge from
//    XlaRecvAtHost node to the node;
// 6. Try pruning XlaRecvAtHost/XlaSendFromHost/key placeholder node.
// 7. Add necessary attributes to `node_def`, so we can replace it with a
//    XlaHostCompute node later. If all input shapes for XlaSendFromHost are
//    known, "shapes" attr will be set to the list of input shapes; otherwise
//    "shape_inference_graph" attr will be set to shape inference function name.
class RewriteOutsideCompilationSubgraphFn {
 public:
  RewriteOutsideCompilationSubgraphFn(
      const string& xla_cluster_attr_name,
      const string& outside_compilation_attr_name,
      const string& xla_cluster_name, const string& new_function_name)
      : xla_cluster_attr_name_(xla_cluster_attr_name),
        outside_compilation_attr_name_(outside_compilation_attr_name),
        xla_cluster_name_(xla_cluster_name),
        new_function_name_(new_function_name) {}

Status operator()(const std::vector<OutputTensor>&,
                    std::unique_ptr<Graph>* graph,
                    std::vector<int>* input_permutation,
                    std::vector<int>* output_permutation, NodeDef* node_def);

private:
  string xla_cluster_attr_name_;
  string outside_compilation_attr_name_;
  string xla_cluster_name_;
  string new_function_name_;
};

// For an XLA computation function, replace all outside compilations with
// XlaHostCompute nodes. Each outside compilation subgraph will be rewritten by
// `RewriteOutsideCompilationSubgraphFn`, and they will be merged into one
// single host side graph (`host_graph`).
//
// xla_cluster_attr_name and outside_compilation_attr_name: attr name for XLA
//   computation and outside compilation. Required for
//   `RewriteOutsideCompilationSubgraphFn`.
// xla_cluster_name: XLA cluster name for this XLA computation. We need it
//   because XLA cluster name might be different from `func_name`.
// func_name_attrs: they will be used to instantiate the XLA computation func.
// new_func_name: new function name for rewritten XLA computation func.
// host_compute_core: mapping from outside compilation cluster name to XLA
//   device assignment.
// fld: FunctionLibraryDefinition object.
// host_graph: Graph object to store host side graph for all outside
//   compilations within this XLA computation func. If there is no outside
//   compilation, it will be empty.
// shape_inference_graphs: a list of outside compilation shape inference
//   function names. These functions need to be rewritten later.
// has_outside_compilation: a bool indicating whether this function has any
//   outside compilation nodes.
Status ExtractOutsideCompilationForFunction(
    const string& xla_cluster_attr_name,
    const string& outside_compilation_attr_name, const string& xla_cluster_name,
    const NameAttrList& func_name_attrs, const string& new_func_name,
    const string& host_graph_func_name,
    const std::map<string, int>& host_compute_core, FunctionLibraryRuntime* flr,
    FunctionLibraryDefinition* fld, std::vector<string>* shape_inference_graphs,
    bool* has_outside_compilation);

// Rewrites XLA computation in `clusters` to replace outside compilation nodes
// with XlaHostCompute, and moves those outside compilations into `g`. If shapes
// of outside compilation outputs cannot be determined now, we will store shape
// inference graph into `fld`.
Status ExtractOutsideCompilation(
    const string& xla_cluster_attr_name,
    const string& outside_compilation_attr_name,
    const std::unordered_map<string, XlaClusterInfo>& clusters, Graph* g,
    FunctionLibraryRuntime* flr, FunctionLibraryDefinition* fld,
    bool* modified);

}  // namespace tensorflow

#endif  // TENSORFLOW_COMPILER_JIT_EXTRACT_OUTSIDE_COMPILATION_PASS_H_