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
17namespace fuzzer {
18
19// A bit map containing kMapSizeInWords bits.
20struct 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);
24  static const size_t kMapSizeInWords = kMapSizeInBitsAligned / kBitsInWord;
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.
53  ATTRIBUTE_TARGET_POPCNT
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
88