xgboost
bitfield.h
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1 
5 #ifndef XGBOOST_COMMON_BITFIELD_H_
6 #define XGBOOST_COMMON_BITFIELD_H_
7 
8 #include <algorithm>
9 #include <bitset>
10 #include <cinttypes>
11 #include <iostream>
12 #include <sstream>
13 #include <string>
14 #include <vector>
15 
16 #if defined(__CUDACC__)
17 #include <thrust/copy.h>
18 #include <thrust/device_ptr.h>
19 #include "device_helpers.cuh"
20 #endif // defined(__CUDACC__)
21 
22 #include "xgboost/span.h"
23 #include "common.h"
24 
25 namespace xgboost {
26 
27 #if defined(__CUDACC__)
28 using BitFieldAtomicType = unsigned long long; // NOLINT
29 
30 __forceinline__ __device__ BitFieldAtomicType AtomicOr(BitFieldAtomicType* address,
31  BitFieldAtomicType val) {
32  BitFieldAtomicType old = *address, assumed; // NOLINT
33  do {
34  assumed = old;
35  old = atomicCAS(address, assumed, val | assumed);
36  } while (assumed != old);
37 
38  return old;
39 }
40 
41 __forceinline__ __device__ BitFieldAtomicType AtomicAnd(BitFieldAtomicType* address,
42  BitFieldAtomicType val) {
43  BitFieldAtomicType old = *address, assumed; // NOLINT
44  do {
45  assumed = old;
46  old = atomicCAS(address, assumed, val & assumed);
47  } while (assumed != old);
48 
49  return old;
50 }
51 #endif // defined(__CUDACC__)
52 
58 template <typename VT, typename Direction, bool IsConst = false>
60  using value_type = std::conditional_t<IsConst, VT const, VT>; // NOLINT
61  using pointer = value_type*; // NOLINT
62 
63  static value_type constexpr kValueSize = sizeof(value_type) * 8;
64  static value_type constexpr kOne = 1; // force correct type.
65 
66  struct Pos {
67  std::remove_const_t<value_type> int_pos {0};
68  std::remove_const_t<value_type> bit_pos {0};
69  };
70 
71  private:
73  static_assert(!std::is_signed<VT>::value, "Must use unsiged type as underlying storage.");
74 
75  public:
77  Pos pos_v;
78  if (pos == 0) {
79  return pos_v;
80  }
81  pos_v.int_pos = pos / kValueSize;
82  pos_v.bit_pos = pos % kValueSize;
83  return pos_v;
84  }
85 
86  public:
87  BitFieldContainer() = default;
89  XGBOOST_DEVICE BitFieldContainer(BitFieldContainer const& other) : bits_{other.bits_} {}
90 
91  common::Span<value_type> Bits() { return bits_; }
92  common::Span<value_type const> Bits() const { return bits_; }
93 
94  /*\brief Compute the size of needed memory allocation. The returned value is in terms
95  * of number of elements with `BitFieldContainer::value_type'.
96  */
97  XGBOOST_DEVICE static size_t ComputeStorageSize(size_t size) {
98  return common::DivRoundUp(size, kValueSize);
99  }
100 #if defined(__CUDA_ARCH__)
101  __device__ BitFieldContainer& operator|=(BitFieldContainer const& rhs) {
102  auto tid = blockIdx.x * blockDim.x + threadIdx.x;
103  size_t min_size = min(bits_.size(), rhs.bits_.size());
104  if (tid < min_size) {
105  bits_[tid] |= rhs.bits_[tid];
106  }
107  return *this;
108  }
109 #else
111  size_t min_size = std::min(bits_.size(), rhs.bits_.size());
112  for (size_t i = 0; i < min_size; ++i) {
113  bits_[i] |= rhs.bits_[i];
114  }
115  return *this;
116  }
117 #endif // #if defined(__CUDA_ARCH__)
118 
119 #if defined(__CUDA_ARCH__)
120  __device__ BitFieldContainer& operator&=(BitFieldContainer const& rhs) {
121  size_t min_size = min(bits_.size(), rhs.bits_.size());
122  auto tid = blockIdx.x * blockDim.x + threadIdx.x;
123  if (tid < min_size) {
124  bits_[tid] &= rhs.bits_[tid];
125  }
126  return *this;
127  }
128 #else
130  size_t min_size = std::min(bits_.size(), rhs.bits_.size());
131  for (size_t i = 0; i < min_size; ++i) {
132  bits_[i] &= rhs.bits_[i];
133  }
134  return *this;
135  }
136 #endif // defined(__CUDA_ARCH__)
137 
138 #if defined(__CUDA_ARCH__)
139  __device__ auto Set(value_type pos) {
140  Pos pos_v = Direction::Shift(ToBitPos(pos));
141  value_type& value = bits_[pos_v.int_pos];
142  value_type set_bit = kOne << pos_v.bit_pos;
143  using Type = typename dh::detail::AtomicDispatcher<sizeof(value_type)>::Type;
144  atomicOr(reinterpret_cast<Type *>(&value), set_bit);
145  }
146  __device__ void Clear(value_type pos) {
147  Pos pos_v = Direction::Shift(ToBitPos(pos));
148  value_type& value = bits_[pos_v.int_pos];
149  value_type clear_bit = ~(kOne << pos_v.bit_pos);
150  using Type = typename dh::detail::AtomicDispatcher<sizeof(value_type)>::Type;
151  atomicAnd(reinterpret_cast<Type *>(&value), clear_bit);
152  }
153 #else
154  void Set(value_type pos) {
155  Pos pos_v = Direction::Shift(ToBitPos(pos));
156  value_type& value = bits_[pos_v.int_pos];
157  value_type set_bit = kOne << pos_v.bit_pos;
158  value |= set_bit;
159  }
160  void Clear(value_type pos) {
161  Pos pos_v = Direction::Shift(ToBitPos(pos));
162  value_type& value = bits_[pos_v.int_pos];
163  value_type clear_bit = ~(kOne << pos_v.bit_pos);
164  value &= clear_bit;
165  }
166 #endif // defined(__CUDA_ARCH__)
167 
168  XGBOOST_DEVICE bool Check(Pos pos_v) const {
169  pos_v = Direction::Shift(pos_v);
170  SPAN_LT(pos_v.int_pos, bits_.size());
171  value_type const value = bits_[pos_v.int_pos];
172  value_type const test_bit = kOne << pos_v.bit_pos;
173  value_type result = test_bit & value;
174  return static_cast<bool>(result);
175  }
176  XGBOOST_DEVICE bool Check(value_type pos) const {
177  Pos pos_v = ToBitPos(pos);
178  return Check(pos_v);
179  }
180 
181  XGBOOST_DEVICE size_t Size() const { return kValueSize * bits_.size(); }
182 
183  XGBOOST_DEVICE pointer Data() const { return bits_.data(); }
184 
185  inline friend std::ostream &
187  os << "Bits " << "storage size: " << field.bits_.size() << "\n";
188  for (typename common::Span<value_type>::index_type i = 0; i < field.bits_.size(); ++i) {
189  std::bitset<BitFieldContainer<VT, Direction, IsConst>::kValueSize> bset(field.bits_[i]);
190  os << bset << "\n";
191  }
192  return os;
193  }
194 };
195 
196 // Bits start from left most bits (most significant bit).
197 template <typename VT, bool IsConst = false>
198 struct LBitsPolicy : public BitFieldContainer<VT, LBitsPolicy<VT, IsConst>, IsConst> {
200  using Pos = typename Container::Pos;
201  using value_type = typename Container::value_type; // NOLINT
202 
203  XGBOOST_DEVICE static Pos Shift(Pos pos) {
204  pos.bit_pos = Container::kValueSize - pos.bit_pos - Container::kOne;
205  return pos;
206  }
207 };
208 
209 // Bits start from right most bit (least significant bit) of each entry, but integer index
210 // is from left to right.
211 template <typename VT>
212 struct RBitsPolicy : public BitFieldContainer<VT, RBitsPolicy<VT>> {
214  using Pos = typename Container::Pos;
215  using value_type = typename Container::value_type; // NOLINT
216 
217  XGBOOST_DEVICE static Pos Shift(Pos pos) {
218  return pos;
219  }
220 };
221 
222 // Format: <Const><Direction>BitField<size of underlying type in bits>, underlying type
223 // must be unsigned.
226 
229 } // namespace xgboost
230 
231 #endif // XGBOOST_COMMON_BITFIELD_H_
xgboost::BitFieldContainer::kOne
static constexpr value_type kOne
Definition: bitfield.h:64
xgboost::BitFieldContainer::Data
XGBOOST_DEVICE pointer Data() const
Definition: bitfield.h:183
xgboost::BitFieldContainer::BitFieldContainer
BitFieldContainer()=default
xgboost::LBitsPolicy::value_type
typename Container::value_type value_type
Definition: bitfield.h:201
xgboost::BitFieldContainer< VT, LBitsPolicy< VT, false >, false >::pointer
value_type * pointer
Definition: bitfield.h:61
xgboost::BitFieldContainer::Clear
void Clear(value_type pos)
Definition: bitfield.h:160
xgboost::BitFieldContainer::ComputeStorageSize
static XGBOOST_DEVICE size_t ComputeStorageSize(size_t size)
Definition: bitfield.h:97
xgboost::BitFieldContainer
A non-owning type with auxiliary methods defined for manipulating bits.
Definition: bitfield.h:59
xgboost::common::Span::index_type
std::size_t index_type
Definition: span.h:416
xgboost::BitFieldContainer::Bits
common::Span< value_type > Bits()
Definition: bitfield.h:91
xgboost::BitFieldContainer::value_type
std::conditional_t< IsConst, VT const, VT > value_type
Definition: bitfield.h:60
xgboost::BitFieldContainer::Pos::int_pos
std::remove_const_t< value_type > int_pos
Definition: bitfield.h:67
xgboost::RBitsPolicy
Definition: bitfield.h:212
xgboost::BitFieldContainer::Bits
common::Span< value_type const > Bits() const
Definition: bitfield.h:92
xgboost::BitFieldContainer::operator&=
BitFieldContainer & operator&=(BitFieldContainer const &rhs)
Definition: bitfield.h:129
span.h
xgboost::RBitsPolicy::Pos
typename Container::Pos Pos
Definition: bitfield.h:214
xgboost::BitFieldContainer::Check
XGBOOST_DEVICE bool Check(Pos pos_v) const
Definition: bitfield.h:168
xgboost::RBitsPolicy::Shift
static XGBOOST_DEVICE Pos Shift(Pos pos)
Definition: bitfield.h:217
xgboost::LBitsPolicy::Pos
typename Container::Pos Pos
Definition: bitfield.h:200
xgboost::LBitsPolicy
Definition: bitfield.h:198
xgboost::common::DivRoundUp
XGBOOST_DEVICE T1 DivRoundUp(const T1 a, const T2 b)
Definition: common.h:84
xgboost::LBitsPolicy::Shift
static XGBOOST_DEVICE Pos Shift(Pos pos)
Definition: bitfield.h:203
xgboost::BitFieldContainer::Pos
Definition: bitfield.h:66
xgboost::BitFieldContainer::kValueSize
static constexpr value_type kValueSize
Definition: bitfield.h:63
SPAN_LT
#define SPAN_LT(lhs, rhs)
Definition: span.h:112
xgboost::BitFieldContainer::ToBitPos
static XGBOOST_DEVICE Pos ToBitPos(value_type pos)
Definition: bitfield.h:76
xgboost::BitFieldContainer::Set
void Set(value_type pos)
Definition: bitfield.h:154
common.h
Common utilities.
xgboost::RBitsPolicy::value_type
typename Container::value_type value_type
Definition: bitfield.h:215
xgboost::common::Span< value_type >
xgboost::BitFieldContainer::Pos::bit_pos
std::remove_const_t< value_type > bit_pos
Definition: bitfield.h:68
xgboost::BitFieldContainer::BitFieldContainer
XGBOOST_DEVICE BitFieldContainer(BitFieldContainer const &other)
Definition: bitfield.h:89
xgboost::common::Span::size
constexpr XGBOOST_DEVICE index_type size() const __span_noexcept
Definition: span.h:542
xgboost::common::Span::data
constexpr XGBOOST_DEVICE pointer data() const __span_noexcept
Definition: span.h:537
xgboost::BitFieldContainer::operator|=
BitFieldContainer & operator|=(BitFieldContainer const &rhs)
Definition: bitfield.h:110
xgboost::BitFieldContainer::Size
XGBOOST_DEVICE size_t Size() const
Definition: bitfield.h:181
xgboost::BitFieldContainer::BitFieldContainer
XGBOOST_DEVICE BitFieldContainer(common::Span< value_type > bits)
Definition: bitfield.h:88
xgboost::BitFieldContainer::operator<<
friend std::ostream & operator<<(std::ostream &os, BitFieldContainer< VT, Direction, IsConst > field)
Definition: bitfield.h:186
XGBOOST_DEVICE
#define XGBOOST_DEVICE
Tag function as usable by device.
Definition: base.h:84
xgboost::BitFieldContainer::Check
XGBOOST_DEVICE bool Check(value_type pos) const
Definition: bitfield.h:176
xgboost
namespace of xgboost
Definition: base.h:110