1 //===- FuzzerValueBitMap.h - INTERNAL - Bit map -----------------*- C++ -* ===//
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 // ValueBitMap.
9 //===----------------------------------------------------------------------===//
10 
11 #ifndef LLVM_FUZZER_VALUE_BIT_MAP_H
12 #define LLVM_FUZZER_VALUE_BIT_MAP_H
13 
14 #include "FuzzerPlatform.h"
15 #include <cstdint>
16 
17 namespace fuzzer {
18 
19 // A bit map containing kMapSizeInWords bits.
20 struct ValueBitMap {
21   static const size_t kMapSizeInBits = 1 << 16;
22   static const size_t kMapPrimeMod = 65371;  // Largest Prime < kMapSizeInBits;
23   static const size_t kBitsInWord = (sizeof(uintptr_t) * 8);
24   static const size_t kMapSizeInWords = kMapSizeInBits / kBitsInWord;
25  public:
26 
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   ATTRIBUTE_NO_SANITIZE_ALL
33   inline bool AddValue(uintptr_t Value) {
34     uintptr_t Idx = Value % kMapSizeInBits;
35     uintptr_t WordIdx = Idx / kBitsInWord;
36     uintptr_t BitIdx = Idx % kBitsInWord;
37     uintptr_t Old = Map[WordIdx];
38     uintptr_t New = Old | (1ULL << BitIdx);
39     Map[WordIdx] = New;
40     return New != Old;
41   }
42 
43   ATTRIBUTE_NO_SANITIZE_ALL
44   inline bool AddValueModPrime(uintptr_t Value) {
45     return AddValue(Value % kMapPrimeMod);
46   }
47 
48   inline bool Get(uintptr_t Idx) {
49     assert(Idx < kMapSizeInBits);
50     uintptr_t WordIdx = Idx / kBitsInWord;
51     uintptr_t BitIdx = Idx % kBitsInWord;
52     return Map[WordIdx] & (1ULL << BitIdx);
53   }
54 
55   size_t SizeInBits() const { return kMapSizeInBits; }
56 
57   template <class Callback>
58   ATTRIBUTE_NO_SANITIZE_ALL
59   void ForEach(Callback CB) const {
60     for (size_t i = 0; i < kMapSizeInWords; i++)
61       if (uintptr_t M = Map[i])
62         for (size_t j = 0; j < sizeof(M) * 8; j++)
63           if (M & ((uintptr_t)1 << j))
64             CB(i * sizeof(M) * 8 + j);
65   }
66 
67  private:
68   ATTRIBUTE_ALIGNED(512) uintptr_t Map[kMapSizeInWords];
69 };
70 
71 }  // namespace fuzzer
72 
73 #endif  // LLVM_FUZZER_VALUE_BIT_MAP_H
74