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deps/json/tests/thirdparty/Fuzzer/FuzzerTracePC.h

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+//===- FuzzerTracePC.h - Internal header for the Fuzzer ---------*- C++ -* ===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// fuzzer::TracePC
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_FUZZER_TRACE_PC
+#define LLVM_FUZZER_TRACE_PC
+
+#include "FuzzerDefs.h"
+#include "FuzzerValueBitMap.h"
+#include <set>
+
+namespace fuzzer {
+
+// TableOfRecentCompares (TORC) remembers the most recently performed
+// comparisons of type T.
+// We record the arguments of CMP instructions in this table unconditionally
+// because it seems cheaper this way than to compute some expensive
+// conditions inside __sanitizer_cov_trace_cmp*.
+// After the unit has been executed we may decide to use the contents of
+// this table to populate a Dictionary.
+template<class T, size_t kSizeT>
+struct TableOfRecentCompares {
+  static const size_t kSize = kSizeT;
+  struct Pair {
+    T A, B;
+  };
+  void Insert(size_t Idx, T Arg1, T Arg2) {
+    Idx = Idx % kSize;
+    Table[Idx].A = Arg1;
+    Table[Idx].B = Arg2;
+  }
+
+  Pair Get(size_t I) { return Table[I % kSize]; }
+
+  Pair Table[kSize];
+};
+
+class TracePC {
+ public:
+  static const size_t kFeatureSetSize = ValueBitMap::kNumberOfItems;
+
+  void HandleTrace(uint32_t *guard, uintptr_t PC);
+  void HandleInit(uint32_t *start, uint32_t *stop);
+  void HandleCallerCallee(uintptr_t Caller, uintptr_t Callee);
+  void HandleValueProfile(size_t Value) { ValueProfileMap.AddValue(Value); }
+  template <class T> void HandleCmp(void *PC, T Arg1, T Arg2);
+  size_t GetTotalPCCoverage();
+  void SetUseCounters(bool UC) { UseCounters = UC; }
+  void SetUseValueProfile(bool VP) { UseValueProfile = VP; }
+  void SetPrintNewPCs(bool P) { DoPrintNewPCs = P; }
+  template <class Callback> size_t CollectFeatures(Callback CB);
+  bool UpdateValueProfileMap(ValueBitMap *MaxValueProfileMap) {
+    return UseValueProfile && MaxValueProfileMap->MergeFrom(ValueProfileMap);
+  }
+
+  void ResetMaps() {
+    ValueProfileMap.Reset();
+    memset(Counters, 0, sizeof(Counters));
+  }
+
+  void UpdateFeatureSet(size_t CurrentElementIdx, size_t CurrentElementSize);
+  void PrintFeatureSet();
+
+  void PrintModuleInfo();
+
+  void PrintCoverage();
+  void DumpCoverage();
+
+  void AddValueForMemcmp(void *caller_pc, const void *s1, const void *s2,
+                         size_t n);
+  void AddValueForStrcmp(void *caller_pc, const char *s1, const char *s2,
+                         size_t n);
+
+  bool UsingTracePcGuard() const {return NumModules; }
+
+  static const size_t kTORCSize = 1 << 5;
+  TableOfRecentCompares<uint32_t, kTORCSize> TORC4;
+  TableOfRecentCompares<uint64_t, kTORCSize> TORC8;
+
+  void PrintNewPCs();
+  size_t GetNumPCs() const { return Min(kNumPCs, NumGuards + 1); }
+  uintptr_t GetPC(size_t Idx) {
+    assert(Idx < GetNumPCs());
+    return PCs[Idx];
+  }
+
+private:
+  bool UseCounters = false;
+  bool UseValueProfile = false;
+  bool DoPrintNewPCs = false;
+
+  struct Module {
+    uint32_t *Start, *Stop;
+  };
+
+  Module Modules[4096];
+  size_t NumModules;  // linker-initialized.
+  size_t NumGuards;  // linker-initialized.
+
+  static const size_t kNumCounters = 1 << 14;
+  alignas(8) uint8_t Counters[kNumCounters];
+
+  static const size_t kNumPCs = 1 << 24;
+  uintptr_t PCs[kNumPCs];
+
+  std::set<uintptr_t> *PrintedPCs;
+
+  ValueBitMap ValueProfileMap;
+};
+
+template <class Callback>
+size_t TracePC::CollectFeatures(Callback CB) {
+  if (!UsingTracePcGuard()) return 0;
+  size_t Res = 0;
+  const size_t Step = 8;
+  assert(reinterpret_cast<uintptr_t>(Counters) % Step == 0);
+  size_t N = Min(kNumCounters, NumGuards + 1);
+  N = (N + Step - 1) & ~(Step - 1);  // Round up.
+  for (size_t Idx = 0; Idx < N; Idx += Step) {
+    uint64_t Bundle = *reinterpret_cast<uint64_t*>(&Counters[Idx]);
+    if (!Bundle) continue;
+    for (size_t i = Idx; i < Idx + Step; i++) {
+      uint8_t Counter = (Bundle >> ((i - Idx) * 8)) & 0xff;
+      if (!Counter) continue;
+      Counters[i] = 0;
+      unsigned Bit = 0;
+      /**/ if (Counter >= 128) Bit = 7;
+      else if (Counter >= 32) Bit = 6;
+      else if (Counter >= 16) Bit = 5;
+      else if (Counter >= 8) Bit = 4;
+      else if (Counter >= 4) Bit = 3;
+      else if (Counter >= 3) Bit = 2;
+      else if (Counter >= 2) Bit = 1;
+      size_t Feature = (i * 8 + Bit);
+      if (CB(Feature))
+        Res++;
+    }
+  }
+  if (UseValueProfile)
+    ValueProfileMap.ForEach([&](size_t Idx) {
+      if (CB(NumGuards * 8 + Idx))
+        Res++;
+    });
+  return Res;
+}
+
+extern TracePC TPC;
+
+}  // namespace fuzzer
+
+#endif  // LLVM_FUZZER_TRACE_PC