1 /* Copyright 2017 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 #ifndef TENSORFLOW_COMPILER_XLA_SERVICE_HLO_CSE_H_ 17 #define TENSORFLOW_COMPILER_XLA_SERVICE_HLO_CSE_H_ 18 19 #include "tensorflow/compiler/xla/service/hlo_module.h" 20 #include "tensorflow/compiler/xla/service/hlo_pass_interface.h" 21 22 namespace xla { 23 24 // A pass which performs common-subexpression elimination. Identical constants 25 // and identical instructions with the same operands are commoned. The pass 26 // iterates over the instructions in topological order which enables the pass to 27 // find arbitrarily large common expressions. 28 class HloCSE : public HloModulePass { 29 public: 30 // If is_layout_sensitive is true, then the simplifier preserves layout during 31 // transformation. Otherwise, layout is ignored. 32 explicit HloCSE(bool is_layout_sensitive, 33 bool only_fusion_computations = false) is_layout_sensitive_(is_layout_sensitive)34 : is_layout_sensitive_(is_layout_sensitive), 35 only_fusion_computations_(only_fusion_computations) {} 36 ~HloCSE() override = default; name()37 absl::string_view name() const override { return "cse"; } 38 39 // Run CSE on the given module. Returns whether the module was changed (common 40 // subexpressions were found and eliminated). 41 StatusOr<bool> Run(HloModule* module) override; 42 43 private: 44 const bool is_layout_sensitive_; 45 const bool only_fusion_computations_; 46 }; 47 48 } // namespace xla 49 50 #endif // TENSORFLOW_COMPILER_XLA_SERVICE_HLO_CSE_H_ 51