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[libFuzzer] speedup path coverage handling

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262102 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kostya Serebryany 2016-02-27 01:50:16 +00:00
parent fbd6d6e52d
commit a6b4efd1d0
2 changed files with 19 additions and 18 deletions
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36
lib/Fuzzer/FuzzerTracePC.cpp
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@ -10,50 +10,50 @@
// This module implements __sanitizer_cov_trace_pc, a callback required
// for -fsanitize-coverage=trace-pc instrumentation.
//
// Experimental and not yet tuned for performance.
//===----------------------------------------------------------------------===//
#include "FuzzerInternal.h"
namespace fuzzer {
static const size_t kMapSize = 65371; // Prime.
static uint8_t CurMap[kMapSize];
static uint8_t CombinedMap[kMapSize];
static const size_t kMapSizeInBits = 65371; // Prime.
static const size_t kMapSizeInBitsAligned = 65536; // 2^16
static const size_t kBitsInWord =(sizeof(uintptr_t) * 8);
static const size_t kMapSizeInWords = kMapSizeInBitsAligned / kBitsInWord;
static uintptr_t CurrentMap[kMapSizeInWords] __attribute__((aligned(512)));
static uintptr_t CombinedMap[kMapSizeInWords] __attribute__((aligned(512)));
static size_t CombinedMapSize;
static thread_local uintptr_t Prev;
void PcMapResetCurrent() {
if (Prev) {
Prev = 0;
memset(CurMap, 0, sizeof(CurMap));
memset(CurrentMap, 0, sizeof(CurrentMap));
}
}
// TODO: speed this up.
void PcMapMergeCurrentToCombined() {
if (!Prev) return;
uintptr_t Res = 0;
for (size_t i = 0; i < kMapSize; i++) {
uint8_t p = (CombinedMap[i] |= CurMap[i]);
CurMap[i] = 0;
Res += p != 0;
}
for (size_t i = 0; i < kMapSizeInWords; i++)
Res += __builtin_popcountl(CombinedMap[i] |= CurrentMap[i]);
CombinedMapSize = Res;
}
size_t PcMapCombinedSize() { return CombinedMapSize; }
static void HandlePC(uintptr_t PC) {
static void HandlePC(uint32_t PC) {
// We take 12 bits of PC and mix it with the previous PCs.
uintptr_t Idx = (Prev << 5) ^ (PC & 4095);
CurMap[Idx % kMapSize] = 1;
Prev = Idx;
uintptr_t Next = (Prev << 5) ^ (PC & 4095);
uintptr_t Idx = Next % kMapSizeInBits;
uintptr_t WordIdx = Idx / kBitsInWord;
uintptr_t BitIdx = Idx % kBitsInWord;
CurrentMap[WordIdx] |= 1UL << BitIdx;
Prev = Next;
}
} // namespace fuzzer
extern "C" void __sanitizer_cov_trace_pc() {
fuzzer::HandlePC(reinterpret_cast<uintptr_t>(__builtin_return_address(0)));
fuzzer::HandlePC(static_cast<uint32_t>(
reinterpret_cast<uintptr_t>(__builtin_return_address(0))));
}
//uintptr_t __sanitizer_get_total_unique_coverage() { return 0; }
//uintptr_t __sanitizer_get_number_of_counters() { return 0; }

1
lib/Fuzzer/test/fuzzer-trace-pc.test
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@ -1,2 +1,3 @@
CHECK: BINGO
RUN: not LLVMFuzzer-FourIndependentBranchesTest-TracePC -seed=1 -runs=1000000 2>&1 | FileCheck %s
RUN: not LLVMFuzzer-FullCoverageSetTest-TracePC -seed=1 -runs=1000000 2>&1 | FileCheck %s