[libFuzzer] use bits instead of bytes for memcmp/strcmp value profile -- the fuzzer reaches the goal much faster, at least on the simple puzzles
llvm-svn: 280054
diff --git a/llvm/lib/Fuzzer/FuzzerTraceState.cpp b/llvm/lib/Fuzzer/FuzzerTraceState.cpp
index 7bbc759..732e1a4 100644
--- a/llvm/lib/Fuzzer/FuzzerTraceState.cpp
+++ b/llvm/lib/Fuzzer/FuzzerTraceState.cpp
@@ -552,26 +552,34 @@
size_t n) {
if (!n) return;
size_t Len = std::min(n, (size_t)32);
- const char *A1 = reinterpret_cast<const char *>(s1);
- const char *A2 = reinterpret_cast<const char *>(s2);
- size_t LastSameByte = 0;
- for (; LastSameByte < Len; LastSameByte++)
- if (A1[LastSameByte] != A2[LastSameByte])
+ const uint8_t *A1 = reinterpret_cast<const uint8_t *>(s1);
+ const uint8_t *A2 = reinterpret_cast<const uint8_t *>(s2);
+ size_t I = 0;
+ for (; I < Len; I++)
+ if (A1[I] != A2[I])
break;
size_t PC = reinterpret_cast<size_t>(caller_pc);
- VP.AddValue((PC & 4095) | (LastSameByte << 12));
+ size_t Idx = I * 8;
+ if (I < Len)
+ Idx += __builtin_popcountl((A1[I] ^ A2[I])) - 1;
+ VP.AddValue((PC & 4095) | (Idx << 12));
}
static void AddValueForStrcmp(void *caller_pc, const char *s1, const char *s2,
size_t n) {
if (!n) return;
size_t Len = std::min(n, (size_t)32);
- size_t LastSameByte = 0;
- for (; LastSameByte < Len; LastSameByte++)
- if (s1[LastSameByte] != s2[LastSameByte] || s1[LastSameByte] == 0)
+ const uint8_t *A1 = reinterpret_cast<const uint8_t *>(s1);
+ const uint8_t *A2 = reinterpret_cast<const uint8_t *>(s2);
+ size_t I = 0;
+ for (; I < Len; I++)
+ if (A1[I] != A2[I] || A1[I] == 0)
break;
size_t PC = reinterpret_cast<size_t>(caller_pc);
- VP.AddValue((PC & 4095) | (LastSameByte << 12));
+ size_t Idx = I * 8;
+ if (I < Len && A1[I])
+ Idx += __builtin_popcountl((A1[I] ^ A2[I])) - 1;
+ VP.AddValue((PC & 4095) | (Idx << 12));
}
ATTRIBUTE_TARGET_POPCNT