LLVM  4.0.0
FuzzerValueBitMap.h
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1 //===- FuzzerValueBitMap.h - INTERNAL - Bit map -----------------*- C++ -* ===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 // ValueBitMap.
10 //===----------------------------------------------------------------------===//
11 
12 #ifndef LLVM_FUZZER_VALUE_BIT_MAP_H
13 #define LLVM_FUZZER_VALUE_BIT_MAP_H
14 
15 #include "FuzzerDefs.h"
16 
17 namespace fuzzer {
18 
19 // A bit map containing kMapSizeInWords bits.
20 struct ValueBitMap {
21  static const size_t kMapSizeInBits = 65371; // Prime.
22  static const size_t kMapSizeInBitsAligned = 65536; // 2^16
23  static const size_t kBitsInWord = (sizeof(uintptr_t) * 8);
25  public:
26  static const size_t kNumberOfItems = kMapSizeInBits;
27  // Clears all bits.
28  void Reset() { memset(Map, 0, sizeof(Map)); }
29 
30  // Computes a hash function of Value and sets the corresponding bit.
31  // Returns true if the bit was changed from 0 to 1.
32  inline bool AddValue(uintptr_t Value) {
33  uintptr_t Idx = Value < kMapSizeInBits ? Value : Value % kMapSizeInBits;
34  uintptr_t WordIdx = Idx / kBitsInWord;
35  uintptr_t BitIdx = Idx % kBitsInWord;
36  uintptr_t Old = Map[WordIdx];
37  uintptr_t New = Old | (1UL << BitIdx);
38  Map[WordIdx] = New;
39  return New != Old;
40  }
41 
42  inline bool Get(uintptr_t Idx) {
43  assert(Idx < kMapSizeInBits);
44  uintptr_t WordIdx = Idx / kBitsInWord;
45  uintptr_t BitIdx = Idx % kBitsInWord;
46  return Map[WordIdx] & (1UL << BitIdx);
47  }
48 
49  size_t GetNumBitsSinceLastMerge() const { return NumBits; }
50 
51  // Merges 'Other' into 'this', clears 'Other', updates NumBits,
52  // returns true if new bits were added.
54  bool MergeFrom(ValueBitMap &Other) {
55  uintptr_t Res = 0;
56  size_t OldNumBits = NumBits;
57  for (size_t i = 0; i < kMapSizeInWords; i++) {
58  auto O = Other.Map[i];
59  auto M = Map[i];
60  if (O) {
61  Map[i] = (M |= O);
62  Other.Map[i] = 0;
63  }
64  if (M)
65  Res += __builtin_popcountl(M);
66  }
67  NumBits = Res;
68  return OldNumBits < NumBits;
69  }
70 
71  template <class Callback>
72  void ForEach(Callback CB) {
73  for (size_t i = 0; i < kMapSizeInWords; i++)
74  if (uintptr_t M = Map[i])
75  for (size_t j = 0; j < sizeof(M) * 8; j++)
76  if (M & ((uintptr_t)1 << j))
77  CB(i * sizeof(M) * 8 + j);
78  }
79 
80  private:
81  size_t NumBits = 0;
82  uintptr_t Map[kMapSizeInWords] __attribute__((aligned(512)));
83 };
84 
85 } // namespace fuzzer
86 
87 #endif // LLVM_FUZZER_VALUE_BIT_MAP_H
size_t i
void ForEach(Callback CB)
size_t GetNumBitsSinceLastMerge() const
bool AddValue(uintptr_t Value)
static const size_t kNumberOfItems
static const size_t kMapSizeInWords
static const size_t kBitsInWord
static const size_t kMapSizeInBits
#define ATTRIBUTE_TARGET_POPCNT
Definition: FuzzerDefs.h:44
static const size_t kMapSizeInBitsAligned
bool Get(uintptr_t Idx)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
ATTRIBUTE_TARGET_POPCNT bool MergeFrom(ValueBitMap &Other)