[llvm] r279588 - [libFuzzer] collect 64 states for value profile, not 65

[Kostya Serebryany via llvm-commits]

Author: kcc
Date: Tue Aug 23 18:37:37 2016
New Revision: 279588

URL: http://llvm.org/viewvc/llvm-project?rev=279588&view=rev
Log:
[libFuzzer] collect 64 states for value profile, not 65

Modified:
    llvm/trunk/lib/Fuzzer/FuzzerTraceState.cpp

Modified: llvm/trunk/lib/Fuzzer/FuzzerTraceState.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/FuzzerTraceState.cpp?rev=279588&r1=279587&r2=279588&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/FuzzerTraceState.cpp (original)
+++ llvm/trunk/lib/Fuzzer/FuzzerTraceState.cpp Tue Aug 23 18:37:37 2016
@@ -576,8 +576,12 @@ static void AddValueForStrcmp(void *call
 
 __attribute__((target("popcnt")))
 static void AddValueForCmp(void *PCptr, uint64_t Arg1, uint64_t Arg2) {
+  if (Arg1 == Arg2)
+    return;
   uintptr_t PC = reinterpret_cast<uintptr_t>(PCptr);
-  VP.AddValue((PC & 4095) | (__builtin_popcountl(Arg1 ^ Arg2) << 12));
+  uint64_t ArgDistance = __builtin_popcountl(Arg1 ^ Arg2) - 1; // [0,63]
+  uintptr_t Idx = (PC & 4095) | (ArgDistance << 12);
+  VP.AddValue(Idx);
 }
 
 }  // namespace fuzzer