1 //===-- include/flang/Evaluate/constant.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_EVALUATE_CONSTANT_H_
10 #define FORTRAN_EVALUATE_CONSTANT_H_
11
12 #include "formatting.h"
13 #include "type.h"
14 #include "flang/Common/default-kinds.h"
15 #include "flang/Common/reference.h"
16 #include <map>
17 #include <vector>
18
19 namespace llvm {
20 class raw_ostream;
21 }
22
23 namespace Fortran::semantics {
24 class Symbol;
25 }
26
27 namespace Fortran::evaluate {
28
29 using semantics::Symbol;
30 using SymbolRef = common::Reference<const Symbol>;
31
32 // Wraps a constant value in a class templated by its resolved type.
33 // This Constant<> template class should be instantiated only for
34 // concrete intrinsic types and SomeDerived. There is no instance
35 // Constant<SomeType> since there is no way to constrain each
36 // element of its array to hold the same type. To represent a generic
37 // constant, use a generic expression like Expr<SomeInteger> or
38 // Expr<SomeType>) to wrap the appropriate instantiation of Constant<>.
39
40 template <typename> class Constant;
41
42 // When describing shapes of constants or specifying 1-based subscript
43 // values as indices into constants, use a vector of integers.
44 using ConstantSubscripts = std::vector<ConstantSubscript>;
GetRank(const ConstantSubscripts & s)45 inline int GetRank(const ConstantSubscripts &s) {
46 return static_cast<int>(s.size());
47 }
48
49 std::size_t TotalElementCount(const ConstantSubscripts &);
50
51 // Validate dimension re-ordering like ORDER in RESHAPE.
52 // On success, return a vector that can be used as dimOrder in
53 // ConstantBound::IncrementSubscripts().
54 std::optional<std::vector<int>> ValidateDimensionOrder(
55 int rank, const std::vector<int> &order);
56
57 bool HasNegativeExtent(const ConstantSubscripts &);
58
59 class ConstantBounds {
60 public:
61 ConstantBounds() = default;
62 explicit ConstantBounds(const ConstantSubscripts &shape);
63 explicit ConstantBounds(ConstantSubscripts &&shape);
64 ~ConstantBounds();
shape()65 const ConstantSubscripts &shape() const { return shape_; }
lbounds()66 const ConstantSubscripts &lbounds() const { return lbounds_; }
67 void set_lbounds(ConstantSubscripts &&);
Rank()68 int Rank() const { return GetRank(shape_); }
69 Constant<SubscriptInteger> SHAPE() const;
70
71 // If no optional dimension order argument is passed, increments a vector of
72 // subscripts in Fortran array order (first dimension varying most quickly).
73 // Otherwise, increments the vector of subscripts according to the given
74 // dimension order (dimension dimOrder[0] varying most quickly; dimension
75 // indexing is zero based here). Returns false when last element was visited.
76 bool IncrementSubscripts(
77 ConstantSubscripts &, const std::vector<int> *dimOrder = nullptr) const;
78
79 protected:
80 ConstantSubscript SubscriptsToOffset(const ConstantSubscripts &) const;
81
82 private:
83 ConstantSubscripts shape_;
84 ConstantSubscripts lbounds_;
85 };
86
87 // Constant<> is specialized for Character kinds and SomeDerived.
88 // The non-Character intrinsic types, and SomeDerived, share enough
89 // common behavior that they use this common base class.
90 template <typename RESULT, typename ELEMENT = Scalar<RESULT>>
91 class ConstantBase : public ConstantBounds {
92 static_assert(RESULT::category != TypeCategory::Character);
93
94 public:
95 using Result = RESULT;
96 using Element = ELEMENT;
97
98 template <typename A>
99 ConstantBase(const A &x, Result res = Result{}) : result_{res}, values_{x} {}
100 ConstantBase(ELEMENT &&x, Result res = Result{})
101 : result_{res}, values_{std::move(x)} {}
102 ConstantBase(
103 std::vector<Element> &&, ConstantSubscripts &&, Result = Result{});
104
105 DEFAULT_CONSTRUCTORS_AND_ASSIGNMENTS(ConstantBase)
106 ~ConstantBase();
107
108 bool operator==(const ConstantBase &) const;
empty()109 bool empty() const { return values_.empty(); }
size()110 std::size_t size() const { return values_.size(); }
values()111 const std::vector<Element> &values() const { return values_; }
result()112 constexpr Result result() const { return result_; }
113
GetType()114 constexpr DynamicType GetType() const { return result_.GetType(); }
115 llvm::raw_ostream &AsFortran(llvm::raw_ostream &) const;
116
117 protected:
118 std::vector<Element> Reshape(const ConstantSubscripts &) const;
119 std::size_t CopyFrom(const ConstantBase &source, std::size_t count,
120 ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
121
122 Result result_;
123 std::vector<Element> values_;
124 };
125
126 template <typename T> class Constant : public ConstantBase<T> {
127 public:
128 using Result = T;
129 using Base = ConstantBase<T>;
130 using Element = Scalar<T>;
131
132 using Base::Base;
CLASS_BOILERPLATE(Constant)133 CLASS_BOILERPLATE(Constant)
134
135 std::optional<Scalar<T>> GetScalarValue() const {
136 if (ConstantBounds::Rank() == 0) {
137 return Base::values_.at(0);
138 } else {
139 return std::nullopt;
140 }
141 }
142
143 // Apply subscripts.
144 Element At(const ConstantSubscripts &) const;
145
146 Constant Reshape(ConstantSubscripts &&) const;
147 std::size_t CopyFrom(const Constant &source, std::size_t count,
148 ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
149 };
150
151 template <int KIND>
152 class Constant<Type<TypeCategory::Character, KIND>> : public ConstantBounds {
153 public:
154 using Result = Type<TypeCategory::Character, KIND>;
155 using Element = Scalar<Result>;
156
157 CLASS_BOILERPLATE(Constant)
158 explicit Constant(const Scalar<Result> &);
159 explicit Constant(Scalar<Result> &&);
160 Constant(
161 ConstantSubscript length, std::vector<Element> &&, ConstantSubscripts &&);
162 ~Constant();
163
164 bool operator==(const Constant &that) const {
165 return shape() == that.shape() && values_ == that.values_;
166 }
167 bool empty() const;
168 std::size_t size() const;
169
LEN()170 ConstantSubscript LEN() const { return length_; }
171
GetScalarValue()172 std::optional<Scalar<Result>> GetScalarValue() const {
173 if (Rank() == 0) {
174 return values_;
175 } else {
176 return std::nullopt;
177 }
178 }
179
180 // Apply subscripts
181 Scalar<Result> At(const ConstantSubscripts &) const;
182
183 Constant Reshape(ConstantSubscripts &&) const;
184 llvm::raw_ostream &AsFortran(llvm::raw_ostream &) const;
GetType()185 static constexpr DynamicType GetType() {
186 return {TypeCategory::Character, KIND};
187 }
188 std::size_t CopyFrom(const Constant &source, std::size_t count,
189 ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
190
191 private:
192 Scalar<Result> values_; // one contiguous string
193 ConstantSubscript length_;
194 };
195
196 class StructureConstructor;
197 using StructureConstructorValues =
198 std::map<SymbolRef, common::CopyableIndirection<Expr<SomeType>>>;
199
200 template <>
201 class Constant<SomeDerived>
202 : public ConstantBase<SomeDerived, StructureConstructorValues> {
203 public:
204 using Result = SomeDerived;
205 using Element = StructureConstructorValues;
206 using Base = ConstantBase<SomeDerived, StructureConstructorValues>;
207
208 Constant(const StructureConstructor &);
209 Constant(StructureConstructor &&);
210 Constant(const semantics::DerivedTypeSpec &,
211 std::vector<StructureConstructorValues> &&, ConstantSubscripts &&);
212 Constant(const semantics::DerivedTypeSpec &,
213 std::vector<StructureConstructor> &&, ConstantSubscripts &&);
214 CLASS_BOILERPLATE(Constant)
215
216 std::optional<StructureConstructor> GetScalarValue() const;
217 StructureConstructor At(const ConstantSubscripts &) const;
218
219 Constant Reshape(ConstantSubscripts &&) const;
220 std::size_t CopyFrom(const Constant &source, std::size_t count,
221 ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
222 };
223
224 FOR_EACH_LENGTHLESS_INTRINSIC_KIND(extern template class ConstantBase, )
225 extern template class ConstantBase<SomeDerived, StructureConstructorValues>;
226 FOR_EACH_INTRINSIC_KIND(extern template class Constant, )
227
228 #define INSTANTIATE_CONSTANT_TEMPLATES \
229 FOR_EACH_LENGTHLESS_INTRINSIC_KIND(template class ConstantBase, ) \
230 template class ConstantBase<SomeDerived, StructureConstructorValues>; \
231 FOR_EACH_INTRINSIC_KIND(template class Constant, )
232 } // namespace Fortran::evaluate
233 #endif // FORTRAN_EVALUATE_CONSTANT_H_
234