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_DTENSOR_MLIR_COLLECTIVES_H_ 17 #define TENSORFLOW_DTENSOR_MLIR_COLLECTIVES_H_ 18 19 #include <string> 20 21 #include "absl/container/flat_hash_set.h" 22 #include "absl/strings/string_view.h" 23 #include "mlir/IR/Value.h" // from @llvm-project 24 #include "tensorflow/compiler/mlir/tensorflow/ir/tf_device.h" 25 #include "tensorflow/dtensor/cc/tensor_layout.h" 26 27 namespace tensorflow { 28 namespace dtensor { 29 30 // Emits collective ops to convert `input` from `src_layout` to `tgt_layout`. 31 // `src_layout` and `tgt_layout` must have the same rank. For each dimension, 32 // it can only go from sharded to replicated. `input` must have static shapes. 33 StatusOr<mlir::Value> EmitAllGather( 34 mlir::OpBuilder& builder, mlir::Value input, 35 const dtensor::Layout& src_layout, const dtensor::Layout& tgt_layout, 36 llvm::SmallPtrSet<mlir::Operation*, 4>* newly_created_ops = nullptr); 37 38 // Given an input layout and a desired layout, inserts the necessary slice to 39 // slice the original value based on the device id. All ops created by this 40 // function are added to new_created_ops. 41 // 42 // Note that the newly created ops are inserted `after` original_value. 43 StatusOr<const mlir::Value> EmitAllScatter( 44 mlir::OpBuilder& builder, const mlir::Value& original_value, 45 const Layout& original_layout, const Layout& desired_layout, 46 llvm::SmallPtrSet<mlir::Operation*, 4>* newly_created_ops = nullptr); 47 48 // Emits splits and calls EmitAllGather (once) to relayout from the src layout 49 // to the tgt layout on a single mesh. 50 // Shape of input is expected to be the local shape for src_layout. 51 StatusOr<mlir::Value> EmitRelayout( 52 mlir::Value input, const dtensor::Layout& src_layout, 53 const dtensor::Layout& tgt_layout, 54 llvm::SmallPtrSet<mlir::Operation*, 4>* newly_created_ops = nullptr); 55 56 // Emits collective ops to reduce `input` over `reduced_dims`. 57 StatusOr<mlir::Operation*> EmitAllReduce( 58 mlir::OpBuilder& builder, const dtensor::Layout& output_layout, 59 const absl::flat_hash_set<std::string>& reduced_dims, 60 mlir::Operation* input, absl::string_view reduce_op); 61 62 // Given input `tensor` that is sharded across spatial dimensions, conduct 63 // halo exchange such that each spatially sharded input blocks exchange 64 // `halo_size` slice with its neighboring processors. 65 // If the input block is at the left/right/top/bottom edge, then ghost halo 66 // tensor (zero) are padded instead. `mesh_dim` specifies the dimension which 67 // halo exchange will be conducted. For example, if we consider a 4D Tensor 68 // (batch, height, width, channel) that has layout (*, h, w, *). Then, 69 // `mesh_dim` == "w" would mean that halo exchange will occur along the width 70 // dimension. That is halo tensors with right/left neighbors will be exchanged. 71 StatusOr<mlir::Value> EmitHaloExchange(mlir::OpBuilder& builder, int halo_size, 72 const std::string& mesh_dim, 73 const Layout& layout, 74 mlir::Value mesh_coordinates, 75 mlir::tf_device::ClusterOp cluster, 76 mlir::Location location, 77 mlir::Value tensor); 78 79 // Emits a DenseToSparse op followed by a SparseToDenseOp. 80 // This is useful for emitting a Relayout on a SparseTensor. 81 // One usage of this is in EmitRelayout when the input is a SparseTensor. 82 StatusOr<mlir::Value> EmitDenseToSparseToDense( 83 mlir::OpBuilder& builder, mlir::Value input, 84 llvm::SmallPtrSet<mlir::Operation*, 4>* newly_created_ops = nullptr); 85 86 } // namespace dtensor 87 } // namespace tensorflow 88 89 #endif // TENSORFLOW_DTENSOR_MLIR_COLLECTIVES_H_ 90