//===-- include/flang/Runtime/descriptor.h ----------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef FORTRAN_RUNTIME_DESCRIPTOR_H_
#define FORTRAN_RUNTIME_DESCRIPTOR_H_
// Defines data structures used during execution of a Fortran program
// to implement nontrivial dummy arguments, pointers, allocatables,
// function results, and the special behaviors of instances of derived types.
// This header file includes and extends the published language
// interoperability header that is required by the Fortran 2018 standard
// as a subset of definitions suitable for exposure to user C/C++ code.
// User C code is welcome to depend on that ISO_Fortran_binding.h file,
// but should never reference this internal header.
#include "flang/ISO_Fortran_binding_wrapper.h"
#include "flang/Runtime/memory.h"
#include "flang/Runtime/type-code.h"
#include <algorithm>
#include <cassert>
#include <cinttypes>
#include <cstddef>
#include <cstdio>
#include <cstring>
namespace Fortran::runtime::typeInfo {
using TypeParameterValue = std::int64_t;
class DerivedType;
} // namespace Fortran::runtime::typeInfo
namespace Fortran::runtime {
using SubscriptValue = ISO::CFI_index_t;
class Terminator;
RT_VAR_GROUP_BEGIN
static constexpr RT_CONST_VAR_ATTRS int maxRank{CFI_MAX_RANK};
RT_VAR_GROUP_END
// A C++ view of the sole interoperable standard descriptor (ISO::CFI_cdesc_t)
// and its type and per-dimension information.
class Dimension {
public:
RT_API_ATTRS SubscriptValue LowerBound() const { return raw_.lower_bound; }
RT_API_ATTRS SubscriptValue Extent() const { return raw_.extent; }
RT_API_ATTRS SubscriptValue UpperBound() const {
return LowerBound() + Extent() - 1;
}
RT_API_ATTRS SubscriptValue ByteStride() const { return raw_.sm; }
RT_API_ATTRS Dimension &SetBounds(
SubscriptValue lower, SubscriptValue upper) {
if (upper >= lower) {
raw_.lower_bound = lower;
raw_.extent = upper - lower + 1;
} else {
raw_.lower_bound = 1;
raw_.extent = 0;
}
return *this;
}
// Do not use this API to cause the LB of an empty dimension
// to be anything other than 1. Use SetBounds() instead if you can.
RT_API_ATTRS Dimension &SetLowerBound(SubscriptValue lower) {
raw_.lower_bound = lower;
return *this;
}
RT_API_ATTRS Dimension &SetUpperBound(SubscriptValue upper) {
auto lower{raw_.lower_bound};
raw_.extent = upper >= lower ? upper - lower + 1 : 0;
return *this;
}
RT_API_ATTRS Dimension &SetExtent(SubscriptValue extent) {
raw_.extent = extent;
return *this;
}
RT_API_ATTRS Dimension &SetByteStride(SubscriptValue bytes) {
raw_.sm = bytes;
return *this;
}
private:
ISO::CFI_dim_t raw_;
};
// The storage for this object follows the last used dim[] entry in a
// Descriptor (CFI_cdesc_t) generic descriptor. Space matters here, since
// descriptors serve as POINTER and ALLOCATABLE components of derived type
// instances. The presence of this structure is encoded in the
// CFI_cdesc_t.extra field, and the number of elements in the len_[]
// array is determined by derivedType_->LenParameters().
class DescriptorAddendum {
public:
explicit RT_API_ATTRS DescriptorAddendum(
const typeInfo::DerivedType *dt = nullptr)
: derivedType_{dt}, len_{0} {}
RT_API_ATTRS DescriptorAddendum &operator=(const DescriptorAddendum &);
RT_API_ATTRS const typeInfo::DerivedType *derivedType() const {
return derivedType_;
}
RT_API_ATTRS DescriptorAddendum &set_derivedType(
const typeInfo::DerivedType *dt) {
derivedType_ = dt;
return *this;
}
RT_API_ATTRS std::size_t LenParameters() const;
RT_API_ATTRS typeInfo::TypeParameterValue LenParameterValue(int which) const {
return len_[which];
}
static constexpr RT_API_ATTRS std::size_t SizeInBytes(int lenParameters) {
// TODO: Don't waste that last word if lenParameters == 0
return sizeof(DescriptorAddendum) +
std::max(lenParameters - 1, 0) * sizeof(typeInfo::TypeParameterValue);
}
RT_API_ATTRS std::size_t SizeInBytes() const;
RT_API_ATTRS void SetLenParameterValue(
int which, typeInfo::TypeParameterValue x) {
len_[which] = x;
}
void Dump(FILE * = stdout) const;
private:
const typeInfo::DerivedType *derivedType_;
typeInfo::TypeParameterValue len_[1]; // must be the last component
// The LEN type parameter values can also include captured values of
// specification expressions that were used for bounds and for LEN type
// parameters of components. The values have been truncated to the LEN
// type parameter's type, if shorter than 64 bits, then sign-extended.
};
// A C++ view of a standard descriptor object.
class Descriptor {
public:
// Be advised: this class type is not suitable for use when allocating
// a descriptor -- it is a dynamic view of the common descriptor format.
// If used in a simple declaration of a local variable or dynamic allocation,
// the size is going to be correct only by accident, since the true size of
// a descriptor depends on the number of its dimensions and the presence and
// size of an addendum, which depends on the type of the data.
// Use the class template StaticDescriptor (below) to declare a descriptor
// whose type and rank are fixed and known at compilation time. Use the
// Create() static member functions otherwise to dynamically allocate a
// descriptor.
RT_API_ATTRS Descriptor(const Descriptor &);
RT_API_ATTRS Descriptor &operator=(const Descriptor &);
// Returns the number of bytes occupied by an element of the given
// category and kind including any alignment padding required
// between adjacent elements.
static RT_API_ATTRS std::size_t BytesFor(TypeCategory category, int kind);
RT_API_ATTRS void Establish(TypeCode t, std::size_t elementBytes,
void *p = nullptr, int rank = maxRank,
const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other,
bool addendum = false);
RT_API_ATTRS void Establish(TypeCategory, int kind, void *p = nullptr,
int rank = maxRank, const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other,
bool addendum = false);
RT_API_ATTRS void Establish(int characterKind, std::size_t characters,
void *p = nullptr, int rank = maxRank,
const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other,
bool addendum = false);
RT_API_ATTRS void Establish(const typeInfo::DerivedType &dt,
void *p = nullptr, int rank = maxRank,
const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other);
// To create a descriptor for a derived type the caller
// must provide non-null dt argument.
// The addendum argument is only used for testing purposes,
// and it may force a descriptor with an addendum while
// dt may be null.
static RT_API_ATTRS OwningPtr<Descriptor> Create(TypeCode t,
std::size_t elementBytes, void *p = nullptr, int rank = maxRank,
const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other,
bool addendum = false, const typeInfo::DerivedType *dt = nullptr);
static RT_API_ATTRS OwningPtr<Descriptor> Create(TypeCategory, int kind,
void *p = nullptr, int rank = maxRank,
const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other);
static RT_API_ATTRS OwningPtr<Descriptor> Create(int characterKind,
SubscriptValue characters, void *p = nullptr, int rank = maxRank,
const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other);
static RT_API_ATTRS OwningPtr<Descriptor> Create(
const typeInfo::DerivedType &dt, void *p = nullptr, int rank = maxRank,
const SubscriptValue *extent = nullptr,
ISO::CFI_attribute_t attribute = CFI_attribute_other);
RT_API_ATTRS ISO::CFI_cdesc_t &raw() { return raw_; }
RT_API_ATTRS const ISO::CFI_cdesc_t &raw() const { return raw_; }
RT_API_ATTRS std::size_t ElementBytes() const { return raw_.elem_len; }
RT_API_ATTRS int rank() const { return raw_.rank; }
RT_API_ATTRS TypeCode type() const { return TypeCode{raw_.type}; }
RT_API_ATTRS Descriptor &set_base_addr(void *p) {
raw_.base_addr = p;
return *this;
}
RT_API_ATTRS bool IsPointer() const {
return raw_.attribute == CFI_attribute_pointer;
}
RT_API_ATTRS bool IsAllocatable() const {
return raw_.attribute == CFI_attribute_allocatable;
}
RT_API_ATTRS bool IsAllocated() const { return raw_.base_addr != nullptr; }
RT_API_ATTRS Dimension &GetDimension(int dim) {
return *reinterpret_cast<Dimension *>(&raw_.dim[dim]);
}
RT_API_ATTRS const Dimension &GetDimension(int dim) const {
return *reinterpret_cast<const Dimension *>(&raw_.dim[dim]);
}
RT_API_ATTRS std::size_t SubscriptByteOffset(
int dim, SubscriptValue subscriptValue) const {
const Dimension &dimension{GetDimension(dim)};
return (subscriptValue - dimension.LowerBound()) * dimension.ByteStride();
}
RT_API_ATTRS std::size_t SubscriptsToByteOffset(
const SubscriptValue subscript[]) const {
std::size_t offset{0};
for (int j{0}; j < raw_.rank; ++j) {
offset += SubscriptByteOffset(j, subscript[j]);
}
return offset;
}
template <typename A = char>
RT_API_ATTRS A *OffsetElement(std::size_t offset = 0) const {
return reinterpret_cast<A *>(
reinterpret_cast<char *>(raw_.base_addr) + offset);
}
template <typename A>
RT_API_ATTRS A *Element(const SubscriptValue subscript[]) const {
return OffsetElement<A>(SubscriptsToByteOffset(subscript));
}
template <typename A>
RT_API_ATTRS A *ElementComponent(
const SubscriptValue subscript[], std::size_t componentOffset) const {
return OffsetElement<A>(
SubscriptsToByteOffset(subscript) + componentOffset);
}
template <typename A>
RT_API_ATTRS A *ZeroBasedIndexedElement(std::size_t n) const {
SubscriptValue at[maxRank];
if (SubscriptsForZeroBasedElementNumber(at, n)) {
return Element<A>(at);
}
return nullptr;
}
RT_API_ATTRS int GetLowerBounds(SubscriptValue subscript[]) const {
for (int j{0}; j < raw_.rank; ++j) {
subscript[j] = GetDimension(j).LowerBound();
}
return raw_.rank;
}
RT_API_ATTRS int GetShape(SubscriptValue subscript[]) const {
for (int j{0}; j < raw_.rank; ++j) {
subscript[j] = GetDimension(j).Extent();
}
return raw_.rank;
}
// When the passed subscript vector contains the last (or first)
// subscripts of the array, these wrap the subscripts around to
// their first (or last) values and return false.
RT_API_ATTRS bool IncrementSubscripts(
SubscriptValue subscript[], const int *permutation = nullptr) const {
for (int j{0}; j < raw_.rank; ++j) {
int k{permutation ? permutation[j] : j};
const Dimension &dim{GetDimension(k)};
if (subscript[k]++ < dim.UpperBound()) {
return true;
}
subscript[k] = dim.LowerBound();
}
return false;
}
RT_API_ATTRS bool DecrementSubscripts(
SubscriptValue[], const int *permutation = nullptr) const;
// False when out of range.
RT_API_ATTRS bool SubscriptsForZeroBasedElementNumber(
SubscriptValue subscript[], std::size_t elementNumber,
const int *permutation = nullptr) const {
if (raw_.rank == 0) {
return elementNumber == 0;
}
std::size_t dimCoefficient[maxRank];
int k0{permutation ? permutation[0] : 0};
dimCoefficient[0] = 1;
auto coefficient{static_cast<std::size_t>(GetDimension(k0).Extent())};
for (int j{1}; j < raw_.rank; ++j) {
int k{permutation ? permutation[j] : j};
const Dimension &dim{GetDimension(k)};
dimCoefficient[j] = coefficient;
coefficient *= dim.Extent();
}
if (elementNumber >= coefficient) {
return false; // out of range
}
for (int j{raw_.rank - 1}; j > 0; --j) {
int k{permutation ? permutation[j] : j};
const Dimension &dim{GetDimension(k)};
std::size_t quotient{elementNumber / dimCoefficient[j]};
subscript[k] = quotient + dim.LowerBound();
elementNumber -= quotient * dimCoefficient[j];
}
subscript[k0] = elementNumber + GetDimension(k0).LowerBound();
return true;
}
RT_API_ATTRS std::size_t ZeroBasedElementNumber(
const SubscriptValue *, const int *permutation = nullptr) const;
RT_API_ATTRS DescriptorAddendum *Addendum() {
if (HasAddendum()) {
return reinterpret_cast<DescriptorAddendum *>(&GetDimension(rank()));
} else {
return nullptr;
}
}
RT_API_ATTRS const DescriptorAddendum *Addendum() const {
if (HasAddendum()) {
return reinterpret_cast<const DescriptorAddendum *>(
&GetDimension(rank()));
} else {
return nullptr;
}
}
// Returns size in bytes of the descriptor (not the data)
static constexpr RT_API_ATTRS std::size_t SizeInBytes(
int rank, bool addendum = false, int lengthTypeParameters = 0) {
std::size_t bytes{sizeof(Descriptor) - sizeof(Dimension)};
bytes += rank * sizeof(Dimension);
if (addendum || lengthTypeParameters > 0) {
bytes += DescriptorAddendum::SizeInBytes(lengthTypeParameters);
}
return bytes;
}
RT_API_ATTRS std::size_t SizeInBytes() const;
RT_API_ATTRS std::size_t Elements() const;
// Allocate() assumes Elements() and ElementBytes() work;
// define the extents of the dimensions and the element length
// before calling. It (re)computes the byte strides after
// allocation. Does not allocate automatic components or
// perform default component initialization.
RT_API_ATTRS int Allocate();
RT_API_ATTRS void SetByteStrides();
// Deallocates storage; does not call FINAL subroutines or
// deallocate allocatable/automatic components.
RT_API_ATTRS int Deallocate();
// Deallocates storage, including allocatable and automatic
// components. Optionally invokes FINAL subroutines.
RT_API_ATTRS int Destroy(bool finalize = false, bool destroyPointers = false,
Terminator * = nullptr);
RT_API_ATTRS bool IsContiguous(int leadingDimensions = maxRank) const {
auto bytes{static_cast<SubscriptValue>(ElementBytes())};
if (leadingDimensions > raw_.rank) {
leadingDimensions = raw_.rank;
}
bool stridesAreContiguous{true};
for (int j{0}; j < leadingDimensions; ++j) {
const Dimension &dim{GetDimension(j)};
stridesAreContiguous &=
(bytes == dim.ByteStride()) || (dim.Extent() == 1);
bytes *= dim.Extent();
}
// One and zero element arrays are contiguous even if the descriptor
// byte strides are not perfect multiples.
// Arrays with more than 2 elements may also be contiguous even if a
// byte stride in one dimension is not a perfect multiple, as long as
// this is the last dimension, or if the dimension has one extent and
// the following dimension have either one extents or contiguous byte
// strides.
return stridesAreContiguous || bytes == 0;
}
// Establishes a pointer to a section or element.
RT_API_ATTRS bool EstablishPointerSection(const Descriptor &source,
const SubscriptValue *lower = nullptr,
const SubscriptValue *upper = nullptr,
const SubscriptValue *stride = nullptr);
RT_API_ATTRS void ApplyMold(const Descriptor &, int rank);
RT_API_ATTRS void Check() const;
void Dump(FILE * = stdout) const;
// Value of the addendum presence flag.
#define _CFI_ADDENDUM_FLAG 1
// Number of bits needed to be shifted when manipulating the allocator index.
#define _CFI_ALLOCATOR_IDX_SHIFT 1
// Allocator index mask.
#define _CFI_ALLOCATOR_IDX_MASK 0b00001110
RT_API_ATTRS inline bool HasAddendum() const {
return raw_.extra & _CFI_ADDENDUM_FLAG;
}
RT_API_ATTRS inline void SetHasAddendum() {
raw_.extra |= _CFI_ADDENDUM_FLAG;
}
RT_API_ATTRS inline int GetAllocIdx() const {
return (raw_.extra & _CFI_ALLOCATOR_IDX_MASK) >> _CFI_ALLOCATOR_IDX_SHIFT;
}
RT_API_ATTRS inline void SetAllocIdx(int pos) {
raw_.extra &= ~_CFI_ALLOCATOR_IDX_MASK; // Clear the allocator index bits.
raw_.extra |= pos << _CFI_ALLOCATOR_IDX_SHIFT;
}
private:
ISO::CFI_cdesc_t raw_;
};
static_assert(sizeof(Descriptor) == sizeof(ISO::CFI_cdesc_t));
// Properly configured instances of StaticDescriptor will occupy the
// exact amount of storage required for the descriptor, its dimensional
// information, and possible addendum. To build such a static descriptor,
// declare an instance of StaticDescriptor<>, extract a reference to its
// descriptor via the descriptor() accessor, and then built a Descriptor
// therein via descriptor.Establish(), e.g.:
// StaticDescriptor<R,A,LP> statDesc;
// Descriptor &descriptor{statDesc.descriptor()};
// descriptor.Establish( ... );
template <int MAX_RANK = maxRank, bool ADDENDUM = false, int MAX_LEN_PARMS = 0>
class alignas(Descriptor) StaticDescriptor {
public:
RT_OFFLOAD_VAR_GROUP_BEGIN
static constexpr int maxRank{MAX_RANK};
static constexpr int maxLengthTypeParameters{MAX_LEN_PARMS};
static constexpr bool hasAddendum{ADDENDUM || MAX_LEN_PARMS > 0};
static constexpr std::size_t byteSize{
Descriptor::SizeInBytes(maxRank, hasAddendum, maxLengthTypeParameters)};
RT_OFFLOAD_VAR_GROUP_END
RT_API_ATTRS Descriptor &descriptor() {
return *reinterpret_cast<Descriptor *>(storage_);
}
RT_API_ATTRS const Descriptor &descriptor() const {
return *reinterpret_cast<const Descriptor *>(storage_);
}
RT_API_ATTRS void Check() {
assert(descriptor().rank() <= maxRank);
assert(descriptor().SizeInBytes() <= byteSize);
if (DescriptorAddendum * addendum{descriptor().Addendum()}) {
(void)addendum;
assert(hasAddendum);
assert(addendum->LenParameters() <= maxLengthTypeParameters);
} else {
assert(!hasAddendum);
assert(maxLengthTypeParameters == 0);
}
descriptor().Check();
}
private:
char storage_[byteSize]{};
};
} // namespace Fortran::runtime
#endif // FORTRAN_RUNTIME_DESCRIPTOR_H_
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