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| 1 | //===-- Runtime/ragged.h ----------------------------------------*- C++ -*-===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #ifndef FORTRAN_RUNTIME_RAGGED_H_ |
| 10 | #define FORTRAN_RUNTIME_RAGGED_H_ |
| 11 | |
| 12 | #include "flang/Runtime/entry-names.h" |
| 13 | #include <cstdint> |
| 14 | |
| 15 | namespace Fortran::runtime { |
| 16 | |
| 17 | // A ragged array header block. |
| 18 | // The header block is used to create the "array of arrays" ragged data |
| 19 | // structure. It contains a pair in `flags` to indicate if the header points to |
| 20 | // an array of headers (isIndirection) or data elements and the rank of the |
| 21 | // pointed-to array. The rank is the length of the extents vector accessed |
| 22 | // through `extentPointer`. The `bufferPointer` is overloaded |
| 23 | // and is null, points to an array of headers (isIndirection), or data. |
| 24 | // By default, a header is set to zero, which is its unused state. |
| 25 | // The layout of a ragged buffer header is mirrored in the compiler. |
| 26 | struct RaggedArrayHeader { |
| 27 | std::uint64_t flags; |
| 28 | void *bufferPointer; |
| 29 | std::int64_t *extentPointer; |
| 30 | }; |
| 31 | |
| 32 | extern "C" { |
| 33 | |
| 34 | // For more on ragged arrays see https://en.wikipedia.org/wiki/Jagged_array. The |
| 35 | // Flang compiler allocates ragged arrays as a generalization for |
| 36 | // non-rectangular array temporaries. Ragged arrays can be allocated recursively |
| 37 | // and on demand. Structurally, each leaf is an optional rectangular array of |
| 38 | // elements. The shape of each leaf is independent and may be computed on |
| 39 | // demand. Each branch node is an optional, possibly sparse rectangular array of |
| 40 | // headers. The shape of each branch is independent and may be computed on |
| 41 | // demand. Ragged arrays preserve a correspondence between a multidimensional |
| 42 | // iteration space and array access vectors, which is helpful for dependence |
| 43 | // analysis. |
| 44 | |
| 45 | // Runtime helper for allocation of ragged array buffers. |
| 46 | // A pointer to the header block to be allocated is given as header. The flag |
| 47 | // isHeader indicates if a block of headers or data is to be allocated. A |
| 48 | // non-negative rank indicates the length of the extentVector, which is a list |
| 49 | // of non-negative extents. elementSize is the size of a data element in the |
| 50 | // rectangular space defined by the extentVector. |
| 51 | void *RTDECL(RaggedArrayAllocate)(void *header, bool isHeader, |
| 52 | std::int64_t rank, std::int64_t elementSize, std::int64_t *extentVector); |
| 53 | |
| 54 | // Runtime helper for deallocation of ragged array buffers. The root header of |
| 55 | // the ragged array structure is passed to deallocate the entire ragged array. |
| 56 | void RTDECL(RaggedArrayDeallocate)(void *raggedArrayHeader); |
| 57 | |
| 58 | } // extern "C" |
| 59 | } // namespace Fortran::runtime |
| 60 | #endif // FORTRAN_RUNTIME_RAGGED_H_ |
| 61 |
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