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 // Utility functions related to layouts of Shapes. 17 18 #ifndef TENSORFLOW_COMPILER_XLA_LAYOUT_UTIL_H_ 19 #define TENSORFLOW_COMPILER_XLA_LAYOUT_UTIL_H_ 20 21 #include <string> 22 23 #include "absl/types/span.h" 24 #include "tensorflow/compiler/xla/layout.h" 25 #include "tensorflow/compiler/xla/shape.h" 26 #include "tensorflow/compiler/xla/status.h" 27 #include "tensorflow/compiler/xla/types.h" 28 #include "tensorflow/compiler/xla/xla_data.pb.h" 29 #include "tensorflow/core/platform/macros.h" 30 #include "tensorflow/core/platform/types.h" 31 32 namespace xla { 33 34 // Namespaced collection of (static) Layout utilities. 35 class LayoutUtil { 36 public: 37 // Creates a layout with the given minor-to-major dimension order. (This is a 38 // convenience function for protobuf construction.) 39 static Layout MakeLayout(absl::Span<const int64> minor_to_major, 40 absl::Span<const Tile> tiles = {}, 41 int64 element_size_in_bits = 0, 42 int64 memory_space = 0); 43 44 // Similar to MakeLayout, but take indices in reverse order. 45 static Layout MakeLayoutFromMajorToMinor( 46 absl::Span<const int64> major_to_minor); 47 48 // Returns a layout with descending ((i.e. {n, n-1, ..., 0}) minor-to-major 49 // dimensions. 50 static Layout MakeDescendingLayout(int64 rank); 51 52 // Returns default layout for the given shape. 53 static Layout GetDefaultLayoutForShape(const Shape& shape); 54 55 // Helper functions that create default layouts for various ranks. 56 static Layout GetDefaultLayoutForRank(int64 rank); 57 static Layout GetDefaultLayoutForR2(); 58 static Layout GetDefaultLayoutForR3(); 59 static Layout GetDefaultLayoutForR4(); 60 61 // Sets the default layout on the Shape. 62 static void SetToDefaultLayout(Shape* shape); 63 64 // Returns a shape with the same dimensions as `shape` but with the default 65 // layout. 66 static Shape GetWithDefaultLayout(const Shape& shape); 67 68 // Sets the layouts of all Shapes within the given ProgramShape to the 69 // default. 70 static void SetToDefaultLayout(ProgramShape* program_shape); 71 72 // Validates that the layout within the given shape is correct. The check 73 // is performed for all subshapes as well. If missing layouts are allowed 74 // the check does not fail on array shapes without layouts. 75 static Status ValidateLayoutInShape(const Shape& shape, 76 bool allow_missing_layouts = false); 77 78 // Validates that the provided layout satisfies invariants for the given 79 // shape. 80 static Status ValidateLayoutForShape(const Layout& layout, 81 const Shape& shape); 82 83 // Clears the layout in the given Shape. After this function is called, 84 // HasLayout will return false for the shape. 85 static void ClearLayout(Shape* shape); 86 87 // Clears the layout on all Shapes within the given ProgramShape. 88 static void ClearLayout(ProgramShape* program_shape); 89 90 // Returns whether the given Shape is an array and has a dense format layout. 91 static bool IsDenseArray(const Shape& shape); 92 93 // Returns whether the given Layout has a dense format. 94 static bool IsDense(const Layout& layout); 95 96 // Returns whether the layout is monotonic and dim 0 is minor in the layout. 97 // * R0 and R1: this is always trivially true. 98 // * R2+: equivalent to column-major. Dimension 0 is the minor, dimension 1 is 99 // more major, and so on until dimension N-1 which is the major. 100 static bool IsMonotonicWithDim0Minor(const Layout& layout); 101 102 // Returns whether the layout is monotonic and dim 0 is major in the layout. 103 // * R0 and R1: this is always trivially true. 104 // * R2+: equivalent to row-major. Dimension 0 is the major, dimension 1 is 105 // more minor, and so on until dimension N-1 which is the minor. 106 static bool IsMonotonicWithDim0Major(const Layout& layout); 107 108 // Returns whether the given shape has a layout. For tuple shapes, true is 109 // returned only if all elements have layouts. 110 static bool HasLayout(const Shape& shape); 111 112 // Returns whether all Shapes within the given ProgramShape have layouts. 113 static bool HasLayout(const ProgramShape& program_shape); 114 115 // Returns whether lhs and rhs are identical. 116 static bool Equal(const Layout& lhs, const Layout& rhs); 117 118 // Returns the minor_to_major array for the given Shape. Requires that the 119 // shape is an array and has a dense layout. 120 static absl::Span<const int64> MinorToMajor(const Shape& shape); 121 static absl::Span<const int64> MinorToMajor(const Layout& layout); 122 123 // Major(0) is the most major logical dimension number, Major(1) is the 124 // second-most-major logical dimension number and so on. 125 // 126 // This can be used to translate physical dimension numbers to logical 127 // dimension numbers. Assume that we are numbering the physical dimensions so 128 // that the most major physical dimension has physical dimension number 0 and 129 // so on. Then a physical dimension number p corresponds to the logical 130 // dimension number Major(p). So this function could also be called 131 // PhysicalToLogical(). 132 // 133 // As an example, consider physical dimension number 0, which by definition is 134 // the most major. Then Major(0) is the most major logical dimension, so Major 135 // maps the physical dimension number 0 to the most major logical dimension 136 // number Major(0). 137 static int64 Major(const Layout& layout, int64 physical_dimension_number); 138 139 // Minor(0) is the most minor logical dimension number, minor(1) is the 140 // second-most-minor logical dimension number and so on. 141 static int64 Minor(const Layout& layout, int64 physical_dimension_number); 142 143 // Returns the inverse mapping of the Major() function. More precisely, return 144 // a vector v such that if l == Major(p), then v[l] == p. 145 // 146 // This can be used to translate logical dimension numbers into physical 147 // dimension numbers. Assume that we are numbering the physical dimensions so 148 // that the most major physical dimension has physical dimension number 0 and 149 // so on. Then a logical dimension number l corresponds to the physical 150 // dimension number MakeLogicalToPhysical(layout)[l]. 151 // 152 // In the returned vector, the first element represents the most major logical 153 // dimension. The element whose contents are 0 represents the most major 154 // physical dimension, and the element with contents (rank - 1) represents 155 // the most minor physical dimension. 156 static std::vector<int64> MakeLogicalToPhysical(const Layout& layout); 157 158 // Returns a human-readable string that represents the given layout. 159 static string HumanString(const Layout& layout); 160 161 // Copies the layout from 'src' to 'dst'. Recursively copies layouts of 162 // tuples. 'src' and 'dst' need not be compatible but the two shapes must 163 // have the same tuple structure (if any) and arrays must have the same 164 // rank. within the shapes must have the same number of dimensions. 165 static Status CopyLayoutBetweenShapes(const Shape& src, Shape* dst); 166 167 // Returns true if the layouts of lhs and rhs are equal, false 168 // otherwise. Recursively compares layouts of tuples. 169 // 170 // lhs and rhs need not be compatible to have the same layout but the two 171 // shapes must have the same tuple structure (if any) and arrays must have the 172 // same rank. Element type is ignored. 173 static bool LayoutsInShapesEqual(const Shape& lhs, const Shape& rhs); 174 175 // Returns whether the given dimensions are consecutive in the given layout, 176 // not necessarily in the order given. 177 static bool AreDimensionsConsecutive(const Layout& layout, 178 absl::Span<const int64> dims); 179 180 // Compute a hash for `layout`. 181 static size_t Hash(const Layout& layout); 182 183 private: 184 TF_DISALLOW_COPY_AND_ASSIGN(LayoutUtil); 185 }; 186 187 } // namespace xla 188 189 #endif // TENSORFLOW_COMPILER_XLA_LAYOUT_UTIL_H_ 190