EVOLUTION-MANAGER

Edit File: layout_util.h

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you may not use this file except in compliance with the License.
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distributed under the License is distributed on an "AS IS" BASIS,
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==============================================================================*/

// Utility functions related to layouts of Shapes.

#ifndef TENSORFLOW_COMPILER_XLA_LAYOUT_UTIL_H_
#define TENSORFLOW_COMPILER_XLA_LAYOUT_UTIL_H_

#include <string>

#include "absl/types/span.h"
#include "tensorflow/compiler/xla/layout.h"
#include "tensorflow/compiler/xla/shape.h"
#include "tensorflow/compiler/xla/status.h"
#include "tensorflow/compiler/xla/types.h"
#include "tensorflow/compiler/xla/xla_data.pb.h"
#include "tensorflow/core/platform/macros.h"
#include "tensorflow/core/platform/types.h"

namespace xla {

// Namespaced collection of (static) Layout utilities.
class LayoutUtil {
 public:
  // Creates a layout with the given minor-to-major dimension order. (This is a
  // convenience function for protobuf construction.)
  static Layout MakeLayout(absl::Span<const int64> minor_to_major,
                           absl::Span<const Tile> tiles = {},
                           int64 element_size_in_bits = 0,
                           int64 memory_space = 0);

// Similar to MakeLayout, but take indices in reverse order.
  static Layout MakeLayoutFromMajorToMinor(
      absl::Span<const int64> major_to_minor);

// Returns a layout with descending ((i.e. {n, n-1, ..., 0}) minor-to-major
  // dimensions.
  static Layout MakeDescendingLayout(int64 rank);

// Returns default layout for the given shape.
  static Layout GetDefaultLayoutForShape(const Shape& shape);

// Helper functions that create default layouts for various ranks.
  static Layout GetDefaultLayoutForRank(int64 rank);
  static Layout GetDefaultLayoutForR2();
  static Layout GetDefaultLayoutForR3();
  static Layout GetDefaultLayoutForR4();

// Sets the default layout on the Shape.
  static void SetToDefaultLayout(Shape* shape);

// Returns a shape with the same dimensions as `shape` but with the default
  // layout.
  static Shape GetWithDefaultLayout(const Shape& shape);

// Sets the layouts of all Shapes within the given ProgramShape to the
  // default.
  static void SetToDefaultLayout(ProgramShape* program_shape);

// Validates that the layout within the given shape is correct. The check
  // is performed for all subshapes as well. If missing layouts are allowed
  // the check does not fail on array shapes without layouts.
  static Status ValidateLayoutInShape(const Shape& shape,
                                      bool allow_missing_layouts = false);

// Validates that the provided layout satisfies invariants for the given
  // shape.
  static Status ValidateLayoutForShape(const Layout& layout,
                                       const Shape& shape);

// Clears the layout in the given Shape. After this function is called,
  // HasLayout will return false for the shape.
  static void ClearLayout(Shape* shape);

// Clears the layout on all Shapes within the given ProgramShape.
  static void ClearLayout(ProgramShape* program_shape);

// Returns whether the given Shape is an array and has a dense format layout.
  static bool IsDenseArray(const Shape& shape);

// Returns whether the given Layout has a dense format.
  static bool IsDense(const Layout& layout);

// Returns whether the layout is monotonic and dim 0 is minor in the layout.
  // * R0 and R1: this is always trivially true.
  // * R2+: equivalent to column-major. Dimension 0 is the minor, dimension 1 is
  //        more major, and so on until dimension N-1 which is the major.
  static bool IsMonotonicWithDim0Minor(const Layout& layout);

// Returns whether the layout is monotonic and dim 0 is major in the layout.
  // * R0 and R1: this is always trivially true.
  // * R2+: equivalent to row-major. Dimension 0 is the major, dimension 1 is
  //        more minor, and so on until dimension N-1 which is the minor.
  static bool IsMonotonicWithDim0Major(const Layout& layout);

// Returns whether the given shape has a layout. For tuple shapes, true is
  // returned only if all elements have layouts.
  static bool HasLayout(const Shape& shape);

// Returns whether all Shapes within the given ProgramShape have layouts.
  static bool HasLayout(const ProgramShape& program_shape);

// Returns whether lhs and rhs are identical.
  static bool Equal(const Layout& lhs, const Layout& rhs);

// Returns the minor_to_major array for the given Shape.  Requires that the
  // shape is an array and has a dense layout.
  static absl::Span<const int64> MinorToMajor(const Shape& shape);
  static absl::Span<const int64> MinorToMajor(const Layout& layout);

// Major(0) is the most major logical dimension number, Major(1) is the
  // second-most-major logical dimension number and so on.
  //
  // This can be used to translate physical dimension numbers to logical
  // dimension numbers. Assume that we are numbering the physical dimensions so
  // that the most major physical dimension has physical dimension number 0 and
  // so on. Then a physical dimension number p corresponds to the logical
  // dimension number Major(p). So this function could also be called
  // PhysicalToLogical().
  //
  // As an example, consider physical dimension number 0, which by definition is
  // the most major. Then Major(0) is the most major logical dimension, so Major
  // maps the physical dimension number 0 to the most major logical dimension
  // number Major(0).
  static int64 Major(const Layout& layout, int64 physical_dimension_number);

// Minor(0) is the most minor logical dimension number, minor(1) is the
  // second-most-minor logical dimension number and so on.
  static int64 Minor(const Layout& layout, int64 physical_dimension_number);

// Returns the inverse mapping of the Major() function. More precisely, return
  // a vector v such that if l == Major(p), then v[l] == p.
  //
  // This can be used to translate logical dimension numbers into physical
  // dimension numbers. Assume that we are numbering the physical dimensions so
  // that the most major physical dimension has physical dimension number 0 and
  // so on. Then a logical dimension number l corresponds to the physical
  // dimension number MakeLogicalToPhysical(layout)[l].
  //
  // In the returned vector, the first element represents the most major logical
  // dimension. The element whose contents are 0 represents the most major
  // physical dimension, and the element with contents (rank - 1) represents
  // the most minor physical dimension.
  static std::vector<int64> MakeLogicalToPhysical(const Layout& layout);

// Returns a human-readable string that represents the given layout.
  static string HumanString(const Layout& layout);

// Copies the layout from 'src' to 'dst'. Recursively copies layouts of
  // tuples.  'src' and 'dst' need not be compatible but the two shapes must
  // have the same tuple structure (if any) and arrays must have the same
  // rank. within the shapes must have the same number of dimensions.
  static Status CopyLayoutBetweenShapes(const Shape& src, Shape* dst);

// Returns true if the layouts of lhs and rhs are equal, false
  // otherwise. Recursively compares layouts of tuples.
  //
  // lhs and rhs need not be compatible to have the same layout but the two
  // shapes must have the same tuple structure (if any) and arrays must have the
  // same rank. Element type is ignored.
  static bool LayoutsInShapesEqual(const Shape& lhs, const Shape& rhs);

// Returns whether the given dimensions are consecutive in the given layout,
  // not necessarily in the order given.
  static bool AreDimensionsConsecutive(const Layout& layout,
                                       absl::Span<const int64> dims);

// Compute a hash for `layout`.
  static size_t Hash(const Layout& layout);

private:
  TF_DISALLOW_COPY_AND_ASSIGN(LayoutUtil);
};

}  // namespace xla

#endif  // TENSORFLOW_COMPILER_XLA_LAYOUT_UTIL_H_