1//===-- runtime/sum.cpp ---------------------------------------------------===//
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// Implements SUM for all required operand types and shapes.
10//
11// Real and complex SUM reductions attempt to reduce floating-point
12// cancellation on intermediate results by using "Kahan summation"
13// (basically the same as manual "double-double").
14
15#include "reduction-templates.h"
16#include "flang/Common/float128.h"
17#include "flang/Runtime/reduction.h"
18#include <cfloat>
19#include <cinttypes>
20#include <complex>
21
22namespace Fortran::runtime {
23
24template <typename INTERMEDIATE> class IntegerSumAccumulator {
25public:
26 explicit RT_API_ATTRS IntegerSumAccumulator(const Descriptor &array)
27 : array_{array} {}
28 void RT_API_ATTRS Reinitialize() { sum_ = 0; }
29 template <typename A>
30 RT_API_ATTRS void GetResult(A *p, int /*zeroBasedDim*/ = -1) const {
31 *p = static_cast<A>(sum_);
32 }
33 template <typename A>
34 RT_API_ATTRS bool AccumulateAt(const SubscriptValue at[]) {
35 sum_ += *array_.Element<A>(at);
36 return true;
37 }
38
39private:
40 const Descriptor &array_;
41 INTERMEDIATE sum_{0};
42};
43
44template <typename INTERMEDIATE> class RealSumAccumulator {
45public:
46 explicit RT_API_ATTRS RealSumAccumulator(const Descriptor &array)
47 : array_{array} {}
48 void RT_API_ATTRS Reinitialize() { sum_ = correction_ = 0; }
49 template <typename A> RT_API_ATTRS A Result() const { return sum_; }
50 template <typename A>
51 RT_API_ATTRS void GetResult(A *p, int /*zeroBasedDim*/ = -1) const {
52 *p = Result<A>();
53 }
54 template <typename A> RT_API_ATTRS bool Accumulate(A x) {
55 // Kahan summation
56 auto next{x + correction_};
57 auto oldSum{sum_};
58 sum_ += next;
59 correction_ = (sum_ - oldSum) - next; // algebraically zero
60 return true;
61 }
62 template <typename A>
63 RT_API_ATTRS bool AccumulateAt(const SubscriptValue at[]) {
64 return Accumulate(*array_.Element<A>(at));
65 }
66
67private:
68 const Descriptor &array_;
69 INTERMEDIATE sum_{0.0}, correction_{0.0};
70};
71
72template <typename PART> class ComplexSumAccumulator {
73public:
74 explicit RT_API_ATTRS ComplexSumAccumulator(const Descriptor &array)
75 : array_{array} {}
76 void RT_API_ATTRS Reinitialize() {
77 reals_.Reinitialize();
78 imaginaries_.Reinitialize();
79 }
80 template <typename A>
81 RT_API_ATTRS void GetResult(A *p, int /*zeroBasedDim*/ = -1) const {
82 using ResultPart = typename A::value_type;
83 *p = {reals_.template Result<ResultPart>(),
84 imaginaries_.template Result<ResultPart>()};
85 }
86 template <typename A> RT_API_ATTRS bool Accumulate(const A &z) {
87 reals_.Accumulate(z.real());
88 imaginaries_.Accumulate(z.imag());
89 return true;
90 }
91 template <typename A>
92 RT_API_ATTRS bool AccumulateAt(const SubscriptValue at[]) {
93 return Accumulate(*array_.Element<A>(at));
94 }
95
96private:
97 const Descriptor &array_;
98 RealSumAccumulator<PART> reals_{array_}, imaginaries_{array_};
99};
100
101extern "C" {
102RT_EXT_API_GROUP_BEGIN
103
104CppTypeFor<TypeCategory::Integer, 1> RTDEF(SumInteger1)(const Descriptor &x,
105 const char *source, int line, int dim, const Descriptor *mask) {
106 return GetTotalReduction<TypeCategory::Integer, 1>(x, source, line, dim, mask,
107 IntegerSumAccumulator<CppTypeFor<TypeCategory::Integer, 4>>{x}, "SUM");
108}
109CppTypeFor<TypeCategory::Integer, 2> RTDEF(SumInteger2)(const Descriptor &x,
110 const char *source, int line, int dim, const Descriptor *mask) {
111 return GetTotalReduction<TypeCategory::Integer, 2>(x, source, line, dim, mask,
112 IntegerSumAccumulator<CppTypeFor<TypeCategory::Integer, 4>>{x}, "SUM");
113}
114CppTypeFor<TypeCategory::Integer, 4> RTDEF(SumInteger4)(const Descriptor &x,
115 const char *source, int line, int dim, const Descriptor *mask) {
116 return GetTotalReduction<TypeCategory::Integer, 4>(x, source, line, dim, mask,
117 IntegerSumAccumulator<CppTypeFor<TypeCategory::Integer, 4>>{x}, "SUM");
118}
119CppTypeFor<TypeCategory::Integer, 8> RTDEF(SumInteger8)(const Descriptor &x,
120 const char *source, int line, int dim, const Descriptor *mask) {
121 return GetTotalReduction<TypeCategory::Integer, 8>(x, source, line, dim, mask,
122 IntegerSumAccumulator<CppTypeFor<TypeCategory::Integer, 8>>{x}, "SUM");
123}
124#ifdef __SIZEOF_INT128__
125CppTypeFor<TypeCategory::Integer, 16> RTDEF(SumInteger16)(const Descriptor &x,
126 const char *source, int line, int dim, const Descriptor *mask) {
127 return GetTotalReduction<TypeCategory::Integer, 16>(x, source, line, dim,
128 mask, IntegerSumAccumulator<CppTypeFor<TypeCategory::Integer, 16>>{x},
129 "SUM");
130}
131#endif
132
133// TODO: real/complex(2 & 3)
134CppTypeFor<TypeCategory::Real, 4> RTDEF(SumReal4)(const Descriptor &x,
135 const char *source, int line, int dim, const Descriptor *mask) {
136 return GetTotalReduction<TypeCategory::Real, 4>(
137 x, source, line, dim, mask, RealSumAccumulator<double>{x}, "SUM");
138}
139CppTypeFor<TypeCategory::Real, 8> RTDEF(SumReal8)(const Descriptor &x,
140 const char *source, int line, int dim, const Descriptor *mask) {
141 return GetTotalReduction<TypeCategory::Real, 8>(
142 x, source, line, dim, mask, RealSumAccumulator<double>{x}, "SUM");
143}
144#if LDBL_MANT_DIG == 64
145CppTypeFor<TypeCategory::Real, 10> RTDEF(SumReal10)(const Descriptor &x,
146 const char *source, int line, int dim, const Descriptor *mask) {
147 return GetTotalReduction<TypeCategory::Real, 10>(
148 x, source, line, dim, mask, RealSumAccumulator<long double>{x}, "SUM");
149}
150#endif
151#if LDBL_MANT_DIG == 113 || HAS_FLOAT128
152CppTypeFor<TypeCategory::Real, 16> RTDEF(SumReal16)(const Descriptor &x,
153 const char *source, int line, int dim, const Descriptor *mask) {
154 return GetTotalReduction<TypeCategory::Real, 16>(
155 x, source, line, dim, mask, RealSumAccumulator<long double>{x}, "SUM");
156}
157#endif
158
159void RTDEF(CppSumComplex4)(CppTypeFor<TypeCategory::Complex, 4> &result,
160 const Descriptor &x, const char *source, int line, int dim,
161 const Descriptor *mask) {
162 result = GetTotalReduction<TypeCategory::Complex, 4>(
163 x, source, line, dim, mask, ComplexSumAccumulator<double>{x}, "SUM");
164}
165void RTDEF(CppSumComplex8)(CppTypeFor<TypeCategory::Complex, 8> &result,
166 const Descriptor &x, const char *source, int line, int dim,
167 const Descriptor *mask) {
168 result = GetTotalReduction<TypeCategory::Complex, 8>(
169 x, source, line, dim, mask, ComplexSumAccumulator<double>{x}, "SUM");
170}
171#if LDBL_MANT_DIG == 64
172void RTDEF(CppSumComplex10)(CppTypeFor<TypeCategory::Complex, 10> &result,
173 const Descriptor &x, const char *source, int line, int dim,
174 const Descriptor *mask) {
175 result = GetTotalReduction<TypeCategory::Complex, 10>(
176 x, source, line, dim, mask, ComplexSumAccumulator<long double>{x}, "SUM");
177}
178#endif
179#if LDBL_MANT_DIG == 113 || HAS_FLOAT128
180void RTDEF(CppSumComplex16)(CppTypeFor<TypeCategory::Complex, 16> &result,
181 const Descriptor &x, const char *source, int line, int dim,
182 const Descriptor *mask) {
183 result = GetTotalReduction<TypeCategory::Complex, 16>(
184 x, source, line, dim, mask, ComplexSumAccumulator<long double>{x}, "SUM");
185}
186#endif
187
188void RTDEF(SumDim)(Descriptor &result, const Descriptor &x, int dim,
189 const char *source, int line, const Descriptor *mask) {
190 TypedPartialNumericReduction<IntegerSumAccumulator, RealSumAccumulator,
191 ComplexSumAccumulator>(result, x, dim, source, line, mask, "SUM");
192}
193
194RT_EXT_API_GROUP_END
195} // extern "C"
196} // namespace Fortran::runtime
197

source code of flang/runtime/sum.cpp