commit 8ec213360fac769af3c74e74a7cb7d8abed9373f
author Kostya Serebryany <kcc@google.com> Tue Jul 03 22:33:09 2018 +0000
committer Copybara-Service <copybara-worker@google.com> Thu Mar 25 23:17:25 2021 -0700
tree 1df6238272afcd1f65966a60f57407454b2841d1
parent 75457e018cf1e78b2df0d6d4e06a6d94b7e94ebc

[libFuzzer] add one more value profile metric, under a flag (experimental)

llvm-svn: 336234
GitOrigin-RevId: 51ddb8830078f36e7a8109716d03f5ea72e582cc

FuzzerLoop.cpp

diff --git a/FuzzerLoop.cpp b/FuzzerLoop.cpp
index 346f90e..d412b58 100644
--- a/FuzzerLoop.cpp
+++ b/FuzzerLoop.cpp
@@ -148,7 +148,7 @@
   if (Options.DetectLeaks && EF->__sanitizer_install_malloc_and_free_hooks)
     EF->__sanitizer_install_malloc_and_free_hooks(MallocHook, FreeHook);
   TPC.SetUseCounters(Options.UseCounters);
-  TPC.SetUseValueProfile(Options.UseValueProfile);
+  TPC.SetUseValueProfileMask(Options.UseValueProfile);
 
   if (Options.Verbosity)
     TPC.PrintModuleInfo();

FuzzerOptions.h

diff --git a/FuzzerOptions.h b/FuzzerOptions.h
index 26487d9..ab90df8 100644
--- a/FuzzerOptions.h
+++ b/FuzzerOptions.h
@@ -31,7 +31,7 @@
   bool UseCounters = false;
   bool UseMemmem = true;
   bool UseCmp = false;
-  bool UseValueProfile = false;
+  int UseValueProfile = false;
   bool Shrink = false;
   bool ReduceInputs = false;
   int ReloadIntervalSec = 1;

FuzzerTracePC.cpp

diff --git a/FuzzerTracePC.cpp b/FuzzerTracePC.cpp
index 540d888..19c1eaf 100644
--- a/FuzzerTracePC.cpp
+++ b/FuzzerTracePC.cpp
@@ -356,7 +356,14 @@
       TORC4.Insert(ArgXor, Arg1, Arg2);
   else if (sizeof(T) == 8)
       TORC8.Insert(ArgXor, Arg1, Arg2);
-  ValueProfileMap.AddValue(Idx);
+  // TODO: remove these flags and instead use all metrics at once.
+  if (UseValueProfileMask & 1)
+    ValueProfileMap.AddValue(Idx);
+  if (UseValueProfileMask & 2)
+    ValueProfileMap.AddValue(
+        PC * 64 + (Arg1 == Arg2 ? 0 : __builtin_clzll(Arg1 - Arg2) + 1));
+  if (UseValueProfileMask & 4)  // alternative way to use the hamming distance
+    ValueProfileMap.AddValue(PC * 64 + ArgDistance);
 }
 
 static size_t InternalStrnlen(const char *S, size_t MaxLen) {

FuzzerTracePC.h

diff --git a/FuzzerTracePC.h b/FuzzerTracePC.h
index c17626c..d397bed 100644
--- a/FuzzerTracePC.h
+++ b/FuzzerTracePC.h
@@ -80,7 +80,7 @@
   template <class T> void HandleCmp(uintptr_t PC, T Arg1, T Arg2);
   size_t GetTotalPCCoverage();
   void SetUseCounters(bool UC) { UseCounters = UC; }
-  void SetUseValueProfile(bool VP) { UseValueProfile = VP; }
+  void SetUseValueProfileMask(uint32_t VPMask) { UseValueProfileMask = VPMask; }
   void SetPrintNewPCs(bool P) { DoPrintNewPCs = P; }
   void SetPrintNewFuncs(size_t P) { NumPrintNewFuncs = P; }
   void UpdateObservedPCs();
@@ -137,7 +137,7 @@
 
 private:
   bool UseCounters = false;
-  bool UseValueProfile = false;
+  uint32_t UseValueProfileMask = false;
   bool DoPrintNewPCs = false;
   size_t NumPrintNewFuncs = 0;
 
@@ -260,7 +260,7 @@
                      Handle8bitCounter);
   FirstFeature += (ExtraCountersEnd() - ExtraCountersBegin()) * 8;
 
-  if (UseValueProfile) {
+  if (UseValueProfileMask) {
     ValueProfileMap.ForEach([&](size_t Idx) {
       HandleFeature(FirstFeature + Idx);
     });