//===-- include/flang/Evaluate/constant.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_EVALUATE_CONSTANT_H_
#define FORTRAN_EVALUATE_CONSTANT_H_
#include "formatting.h"
#include "type.h"
#include "flang/Common/default-kinds.h"
#include "flang/Common/reference.h"
#include <map>
#include <vector>
namespace llvm {
class raw_ostream;
}
namespace Fortran::semantics {
class Symbol;
}
namespace Fortran::evaluate {
using semantics::Symbol;
using SymbolRef = common::Reference<const Symbol>;
// Wraps a constant value in a class templated by its resolved type.
// This Constant<> template class should be instantiated only for
// concrete intrinsic types and SomeDerived. There is no instance
// Constant<SomeType> since there is no way to constrain each
// element of its array to hold the same type. To represent a generic
// constant, use a generic expression like Expr<SomeInteger> or
// Expr<SomeType>) to wrap the appropriate instantiation of Constant<>.
template <typename> class Constant;
// When describing shapes of constants or specifying 1-based subscript
// values as indices into constants, use a vector of integers.
using ConstantSubscripts = std::vector<ConstantSubscript>;
inline int GetRank(const ConstantSubscripts &s) {
return static_cast<int>(s.size());
}
// Returns the number of elements of shape, if no overflow occurs.
std::optional<uint64_t> TotalElementCount(const ConstantSubscripts &shape);
// Validate dimension re-ordering like ORDER in RESHAPE.
// On success, return a vector that can be used as dimOrder in
// ConstantBounds::IncrementSubscripts().
std::optional<std::vector<int>> ValidateDimensionOrder(
int rank, const std::vector<int> &order);
bool HasNegativeExtent(const ConstantSubscripts &);
class ConstantBounds {
public:
ConstantBounds() = default;
explicit ConstantBounds(const ConstantSubscripts &shape);
explicit ConstantBounds(ConstantSubscripts &&shape);
~ConstantBounds();
const ConstantSubscripts &shape() const { return shape_; }
int Rank() const { return GetRank(shape_); }
Constant<SubscriptInteger> SHAPE() const;
// It is possible in this representation for a constant array to have
// lower bounds other than 1, which is of course not expressible in
// Fortran. This case arises only from definitions of named constant
// arrays with such bounds, as in:
// REAL, PARAMETER :: NAMED(0:1) = [1.,2.]
// Bundling the lower bounds of the named constant with its
// constant value allows folding of subscripted array element
// references, LBOUND, and UBOUND without having to thread the named
// constant or its bounds throughout folding.
const ConstantSubscripts &lbounds() const { return lbounds_; }
ConstantSubscripts ComputeUbounds(std::optional<int> dim) const;
void set_lbounds(ConstantSubscripts &&);
void SetLowerBoundsToOne();
bool HasNonDefaultLowerBound() const;
// If no optional dimension order argument is passed, increments a vector of
// subscripts in Fortran array order (first dimension varying most quickly).
// Otherwise, increments the vector of subscripts according to the given
// dimension order (dimension dimOrder[0] varying most quickly; dimension
// indexing is zero based here). Returns false when last element was visited.
bool IncrementSubscripts(
ConstantSubscripts &, const std::vector<int> *dimOrder = nullptr) const;
protected:
ConstantSubscript SubscriptsToOffset(const ConstantSubscripts &) const;
private:
ConstantSubscripts shape_;
ConstantSubscripts lbounds_;
};
// Constant<> is specialized for Character kinds and SomeDerived.
// The non-Character intrinsic types, and SomeDerived, share enough
// common behavior that they use this common base class.
template <typename RESULT, typename ELEMENT = Scalar<RESULT>>
class ConstantBase : public ConstantBounds {
static_assert(RESULT::category != TypeCategory::Character);
public:
using Result = RESULT;
using Element = ELEMENT;
template <typename A>
ConstantBase(const A &x, Result res = Result{}) : result_{res}, values_{x} {}
ConstantBase(ELEMENT &&x, Result res = Result{})
: result_{res}, values_{std::move(x)} {}
ConstantBase(
std::vector<Element> &&, ConstantSubscripts &&, Result = Result{});
DEFAULT_CONSTRUCTORS_AND_ASSIGNMENTS(ConstantBase)
~ConstantBase();
bool operator==(const ConstantBase &) const;
bool empty() const { return values_.empty(); }
std::size_t size() const { return values_.size(); }
const std::vector<Element> &values() const { return values_; }
constexpr Result result() const { return result_; }
constexpr DynamicType GetType() const { return result_.GetType(); }
llvm::raw_ostream &AsFortran(llvm::raw_ostream &) const;
protected:
std::vector<Element> Reshape(const ConstantSubscripts &) const;
std::size_t CopyFrom(const ConstantBase &source, std::size_t count,
ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
Result result_;
std::vector<Element> values_;
};
template <typename T> class Constant : public ConstantBase<T> {
public:
using Result = T;
using Base = ConstantBase<T>;
using Element = Scalar<T>;
using Base::Base;
CLASS_BOILERPLATE(Constant)
std::optional<Scalar<T>> GetScalarValue() const {
if (ConstantBounds::Rank() == 0) {
return Base::values_.at(0);
} else {
return std::nullopt;
}
}
// Apply subscripts. Excess subscripts are ignored, including the
// case of a scalar.
Element At(const ConstantSubscripts &) const;
Constant Reshape(ConstantSubscripts &&) const;
std::size_t CopyFrom(const Constant &source, std::size_t count,
ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
};
template <int KIND>
class Constant<Type<TypeCategory::Character, KIND>> : public ConstantBounds {
public:
using Result = Type<TypeCategory::Character, KIND>;
using Element = Scalar<Result>;
CLASS_BOILERPLATE(Constant)
explicit Constant(const Scalar<Result> &);
explicit Constant(Scalar<Result> &&);
Constant(
ConstantSubscript length, std::vector<Element> &&, ConstantSubscripts &&);
~Constant();
bool operator==(const Constant &that) const {
return LEN() == that.LEN() && shape() == that.shape() &&
values_ == that.values_;
}
bool empty() const;
std::size_t size() const;
const Scalar<Result> &values() const { return values_; }
ConstantSubscript LEN() const { return length_; }
bool wasHollerith() const { return wasHollerith_; }
void set_wasHollerith(bool yes = true) { wasHollerith_ = yes; }
std::optional<Scalar<Result>> GetScalarValue() const {
if (Rank() == 0) {
return values_;
} else {
return std::nullopt;
}
}
// Apply subscripts, if any.
Scalar<Result> At(const ConstantSubscripts &) const;
// Extract substring(s); returns nullopt for errors.
std::optional<Constant> Substring(ConstantSubscript, ConstantSubscript) const;
Constant Reshape(ConstantSubscripts &&) const;
llvm::raw_ostream &AsFortran(llvm::raw_ostream &) const;
DynamicType GetType() const { return {KIND, length_}; }
std::size_t CopyFrom(const Constant &source, std::size_t count,
ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
private:
Scalar<Result> values_; // one contiguous string
ConstantSubscript length_;
bool wasHollerith_{false};
};
class StructureConstructor;
struct ComponentCompare {
bool operator()(SymbolRef x, SymbolRef y) const;
};
using StructureConstructorValues = std::map<SymbolRef,
common::CopyableIndirection<Expr<SomeType>>, ComponentCompare>;
template <>
class Constant<SomeDerived>
: public ConstantBase<SomeDerived, StructureConstructorValues> {
public:
using Result = SomeDerived;
using Element = StructureConstructorValues;
using Base = ConstantBase<SomeDerived, StructureConstructorValues>;
Constant(const StructureConstructor &);
Constant(StructureConstructor &&);
Constant(const semantics::DerivedTypeSpec &,
std::vector<StructureConstructorValues> &&, ConstantSubscripts &&);
Constant(const semantics::DerivedTypeSpec &,
std::vector<StructureConstructor> &&, ConstantSubscripts &&);
CLASS_BOILERPLATE(Constant)
std::optional<StructureConstructor> GetScalarValue() const;
StructureConstructor At(const ConstantSubscripts &) const;
bool operator==(const Constant &) const;
Constant Reshape(ConstantSubscripts &&) const;
std::size_t CopyFrom(const Constant &source, std::size_t count,
ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
};
FOR_EACH_LENGTHLESS_INTRINSIC_KIND(extern template class ConstantBase, )
extern template class ConstantBase<SomeDerived, StructureConstructorValues>;
FOR_EACH_INTRINSIC_KIND(extern template class Constant, )
#define INSTANTIATE_CONSTANT_TEMPLATES \
FOR_EACH_LENGTHLESS_INTRINSIC_KIND(template class ConstantBase, ) \
template class ConstantBase<SomeDerived, StructureConstructorValues>; \
FOR_EACH_INTRINSIC_KIND(template class Constant, )
} // namespace Fortran::evaluate
#endif // FORTRAN_EVALUATE_CONSTANT_H_
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