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[libFuzzer] speedup TracePC::FinalizeTrace 

llvm-svn: 282562
This commit is contained in:
Kostya Serebryany 2016-09-28 01:16:24 +00:00
parent 69330e0bc5
commit 3ee6c213d6
2 changed files with 22 additions and 15 deletions
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35
llvm/lib/Fuzzer/FuzzerTracePC.cpp
View File

@ -70,20 +70,27 @@ void TracePC::ResetGuards() {
void TracePC::FinalizeTrace() {
if (TotalPCCoverage) {
for (size_t Idx = 1, N = Min(kNumCounters, NumGuards + 1); Idx < N;
Idx++) {
uint8_t Counter = Counters[Idx];
if (!Counter) continue;
Counters[Idx] = 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;
CounterMap.AddValue(Idx * 8 + Bit);
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 * 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;
CounterMap.AddValue(i * 8 + Bit);
}
}
}
}

2
llvm/lib/Fuzzer/FuzzerTracePC.h
View File

@ -79,7 +79,7 @@ private:
size_t NumGuards = 0;
static const size_t kNumCounters = 1 << 14;
uint8_t Counters[kNumCounters];
alignas(8) uint8_t Counters[kNumCounters];
static const size_t kNumPCs = 1 << 20;
uintptr_t PCs[kNumPCs];