1//===-- lib/runtime/array-constructor.cpp -----------------------*- 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#include "flang-rt/runtime/array-constructor.h"
10#include "flang-rt/runtime/derived.h"
11#include "flang-rt/runtime/descriptor.h"
12#include "flang-rt/runtime/terminator.h"
13#include "flang-rt/runtime/tools.h"
14#include "flang-rt/runtime/type-info.h"
15#include "flang/Runtime/allocatable.h"
16#include "flang/Runtime/assign.h"
17
18namespace Fortran::runtime {
19
20// Initial allocation size for an array constructor temporary whose extent
21// cannot be pre-computed. This could be fined tuned if needed based on actual
22// program performance.
23// REAL(4), INTEGER(4), COMPLEX(2), ... -> 32 elements.
24// REAL(8), INTEGER(8), COMPLEX(4), ... -> 16 elements.
25// REAL(16), INTEGER(16), COMPLEX(8), ... -> 8 elements.
26// Bigger types -> 4 elements.
27static RT_API_ATTRS SubscriptValue initialAllocationSize(
28 SubscriptValue initialNumberOfElements, SubscriptValue elementBytes) {
29 // Try to guess an optimal initial allocation size in number of elements to
30 // avoid doing too many reallocation.
31 static constexpr SubscriptValue minNumberOfBytes{128};
32 static constexpr SubscriptValue minNumberOfElements{4};
33 SubscriptValue numberOfElements{initialNumberOfElements > minNumberOfElements
34 ? initialNumberOfElements
35 : minNumberOfElements};
36 SubscriptValue elementsForMinBytes{minNumberOfBytes / elementBytes};
37 return std::max(numberOfElements, elementsForMinBytes);
38}
39
40static RT_API_ATTRS void AllocateOrReallocateVectorIfNeeded(
41 ArrayConstructorVector &vector, Terminator &terminator,
42 SubscriptValue previousToElements, SubscriptValue fromElements) {
43 Descriptor &to{vector.to};
44 if (to.IsAllocatable() && !to.IsAllocated()) {
45 // The descriptor bounds may already be set here if the array constructor
46 // extent could be pre-computed, but information about length parameters
47 // was missing and required evaluating the first array constructor value.
48 if (previousToElements == 0) {
49 SubscriptValue allocationSize{
50 initialAllocationSize(fromElements, to.ElementBytes())};
51 to.GetDimension(0).SetBounds(1, allocationSize);
52 RTNAME(AllocatableAllocate)
53 (to, /*asyncObject=*/nullptr, /*hasStat=*/false, /*errMsg=*/nullptr,
54 vector.sourceFile, vector.sourceLine);
55 to.GetDimension(0).SetBounds(1, fromElements);
56 vector.actualAllocationSize = allocationSize;
57 } else {
58 // Do not over-allocate if the final extent was known before pushing the
59 // first value: there should be no reallocation.
60 RUNTIME_CHECK(terminator, previousToElements >= fromElements);
61 RTNAME(AllocatableAllocate)
62 (to, /*asyncObject=*/nullptr, /*hasStat=*/false, /*errMsg=*/nullptr,
63 vector.sourceFile, vector.sourceLine);
64 vector.actualAllocationSize = previousToElements;
65 }
66 } else {
67 SubscriptValue newToElements{vector.nextValuePosition + fromElements};
68 if (to.IsAllocatable() && vector.actualAllocationSize < newToElements) {
69 // Reallocate. Ensure the current storage is at least doubled to avoid
70 // doing too many reallocations.
71 SubscriptValue requestedAllocationSize{
72 std::max(newToElements, vector.actualAllocationSize * 2)};
73 std::size_t newByteSize{requestedAllocationSize * to.ElementBytes()};
74 // realloc is undefined with zero new size and ElementBytes() may be null
75 // if the character length is null, or if "from" is a zero sized array.
76 if (newByteSize > 0) {
77 void *p{ReallocateMemoryOrCrash(
78 terminator, to.raw().base_addr, newByteSize)};
79 to.set_base_addr(p);
80 }
81 vector.actualAllocationSize = requestedAllocationSize;
82 to.GetDimension(0).SetBounds(1, newToElements);
83 } else if (previousToElements < newToElements) {
84 // Storage is big enough, but descriptor extent must be increased because
85 // the final extent was not known before pushing array constructor values.
86 to.GetDimension(0).SetBounds(1, newToElements);
87 }
88 }
89}
90
91extern "C" {
92RT_EXT_API_GROUP_BEGIN
93
94void RTDEF(InitArrayConstructorVector)(ArrayConstructorVector &vector,
95 Descriptor &to, bool useValueLengthParameters, const char *sourceFile,
96 int sourceLine) {
97 Terminator terminator{vector.sourceFile, vector.sourceLine};
98 RUNTIME_CHECK(terminator, to.rank() == 1);
99 SubscriptValue actualAllocationSize{
100 to.IsAllocated() ? static_cast<SubscriptValue>(to.Elements()) : 0};
101 (void)new (&vector) ArrayConstructorVector{to, /*nextValuePosition=*/0,
102 actualAllocationSize, sourceFile, sourceLine, useValueLengthParameters};
103}
104
105void RTDEF(PushArrayConstructorValue)(
106 ArrayConstructorVector &vector, const Descriptor &from) {
107 Terminator terminator{vector.sourceFile, vector.sourceLine};
108 Descriptor &to{vector.to};
109 SubscriptValue fromElements{static_cast<SubscriptValue>(from.Elements())};
110 SubscriptValue previousToElements{static_cast<SubscriptValue>(to.Elements())};
111 if (vector.useValueLengthParameters()) {
112 // Array constructor with no type spec.
113 if (to.IsAllocatable() && !to.IsAllocated()) {
114 // Takes length parameters, if any, from the first value.
115 // Note that "to" type must already be set by the caller of this API since
116 // it cannot be taken from "from" here: "from" may be polymorphic (have a
117 // dynamic type that differs from its declared type) and Fortran 2018 7.8
118 // point 4. says that the dynamic type of an array constructor is its
119 // declared type: it does not inherit the dynamic type of its ac-value
120 // even if if there is no type-spec.
121 if (to.type().IsCharacter()) {
122 to.raw().elem_len = from.ElementBytes();
123 } else if (auto *toAddendum{to.Addendum()}) {
124 if (const auto *fromAddendum{from.Addendum()}) {
125 if (const auto *toDerived{toAddendum->derivedType()}) {
126 std::size_t lenParms{toDerived->LenParameters()};
127 for (std::size_t j{0}; j < lenParms; ++j) {
128 toAddendum->SetLenParameterValue(
129 j, fromAddendum->LenParameterValue(j));
130 }
131 }
132 }
133 }
134 } else if (to.type().IsCharacter()) {
135 // Fortran 2018 7.8 point 2.
136 if (to.ElementBytes() != from.ElementBytes()) {
137 terminator.Crash("Array constructor: mismatched character lengths (%d "
138 "!= %d) between "
139 "values of an array constructor without type-spec",
140 to.ElementBytes() / to.type().GetCategoryAndKind()->second,
141 from.ElementBytes() / from.type().GetCategoryAndKind()->second);
142 }
143 }
144 }
145 // Otherwise, the array constructor had a type-spec and the length
146 // parameters are already in the "to" descriptor.
147
148 AllocateOrReallocateVectorIfNeeded(
149 vector, terminator, previousToElements, fromElements);
150
151 // Create descriptor for "to" element or section being copied to.
152 SubscriptValue lower[1]{
153 to.GetDimension(0).LowerBound() + vector.nextValuePosition};
154 SubscriptValue upper[1]{lower[0] + fromElements - 1};
155 SubscriptValue stride[1]{from.rank() == 0 ? 0 : 1};
156 StaticDescriptor<maxRank, true, 1> staticDesc;
157 Descriptor &toCurrentElement{staticDesc.descriptor()};
158 toCurrentElement.EstablishPointerSection(to, lower, upper, stride);
159 // Note: toCurrentElement and from have the same number of elements
160 // and "toCurrentElement" is not an allocatable so AssignTemporary
161 // below works even if "from" rank is bigger than one (and differs
162 // from "toCurrentElement") and not time is wasted reshaping
163 // "toCurrentElement" to "from" shape.
164 RTNAME(AssignTemporary)
165 (toCurrentElement, from, vector.sourceFile, vector.sourceLine);
166 vector.nextValuePosition += fromElements;
167}
168
169void RTDEF(PushArrayConstructorSimpleScalar)(
170 ArrayConstructorVector &vector, void *from) {
171 Terminator terminator{vector.sourceFile, vector.sourceLine};
172 Descriptor &to{vector.to};
173 AllocateOrReallocateVectorIfNeeded(vector, terminator, to.Elements(), 1);
174 SubscriptValue subscript[1]{
175 to.GetDimension(0).LowerBound() + vector.nextValuePosition};
176 std::memcpy(to.Element<char>(subscript), from, to.ElementBytes());
177 ++vector.nextValuePosition;
178}
179
180RT_EXT_API_GROUP_END
181} // extern "C"
182} // namespace Fortran::runtime
183

source code of flang-rt/lib/runtime/array-constructor.cpp