compiler-rt/lib/fuzzer/FuzzerValueBitMap.h

   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