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ReductionOperators.cuh
1 /**
2 * Copyright (c) 2015-present, Facebook, Inc.
3 * All rights reserved.
4 *
5 * This source code is licensed under the CC-by-NC license found in the
6 * LICENSE file in the root directory of this source tree.
7 */
8
9 // Copyright 2004-present Facebook. All Rights Reserved.
10
11 #pragma once
12
13 #include <cuda.h>
14 #include "Limits.cuh"
15 #include "MathOperators.cuh"
16 #include "Pair.cuh"
17
18 namespace faiss { namespace gpu {
19
20 template <typename T>
21 struct Sum {
22 __device__ inline T operator()(T a, T b) const {
23 return Math<T>::add(a, b);
24 }
25
26 inline __device__ T identity() const {
27 return Math<T>::zero();
28 }
29 };
30
31 template <typename T>
32 struct Min {
33 __device__ inline T operator()(T a, T b) const {
34 return Math<T>::lt(a, b) ? a : b;
35 }
36
37 inline __device__ T identity() const {
38 return Limits<T>::getMax();
39 }
40 };
41
42 template <typename T>
43 struct Max {
44 __device__ inline T operator()(T a, T b) const {
45 return Math<T>::gt(a, b) ? a : b;
46 }
47
48 inline __device__ T identity() const {
49 return Limits<T>::getMin();
50 }
51 };
52
53 /// Used for producing segmented prefix scans; the value of the Pair
54 /// denotes the start of a new segment for the scan
55 template <typename T, typename ReduceOp>
56 struct SegmentedReduce {
57 inline __device__ SegmentedReduce(const ReduceOp& o)
58 : op(o) {
59 }
60
61 __device__
62 inline Pair<T, bool>
63 operator()(const Pair<T, bool>& a, const Pair<T, bool>& b) const {
64 return Pair<T, bool>(b.v ? b.k : op(a.k, b.k),
65 a.v || b.v);
66 }
67
68 inline __device__ Pair<T, bool> identity() const {
69 return Pair<T, bool>(op.identity(), false);
70 }
71
72 ReduceOp op;
73 };
74
75 } } // namespace
faiss::gpu::Math
Definition: MathOperators.cuh:24
faiss::gpu::Pair
A simple pair type for CUDA device usage.
Definition: Pair.cuh:21
faiss::gpu::Min
Definition: ReductionOperators.cuh:32
faiss::gpu::Sum
Definition: ReductionOperators.cuh:21
faiss::gpu::SegmentedReduce
Definition: ReductionOperators.cuh:56
faiss::gpu::Max
Definition: ReductionOperators.cuh:43
faiss::gpu::Limits
Definition: Limits.cuh:20