1 /* Copyright 2022 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_CONVERT_MOVER_H_ 17 #define TENSORFLOW_COMPILER_XLA_SERVICE_CONVERT_MOVER_H_ 18 19 #include <functional> 20 #include <utility> 21 22 #include "tensorflow/compiler/xla/service/hlo_pass_interface.h" 23 24 namespace xla { 25 26 // Moves narrowing conversions up the graph and widening conversions down the 27 // graph, when we can do so with no effect on numerics. Motivations: 28 // 29 // - It's preferable to spend more of our time in lower precision and less of 30 // our time in higher precision. 31 // 32 // - Moving these converts exposes optimization opportunities. For example, in 33 // reshape(convert-big-to-small(reshape(convert-small-to-big(x)))), we can 34 // commute one of the converts with one of the reshapes. This leaves us with 35 // convert(convert(reshape(reshape))), which can probably be simplified 36 // further by algsimp. 37 class ConvertMover : public HloModulePass { 38 public: 39 ConvertMover() = default; 40 name()41 absl::string_view name() const override { return "convert-mover"; } 42 StatusOr<bool> Run( 43 HloModule* module, 44 const absl::flat_hash_set<absl::string_view>& execution_threads) override; 45 }; 46 47 } // namespace xla 48 49 #endif // TENSORFLOW_COMPILER_XLA_SERVICE_CONVERT_MOVER_H_ 50