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//===- FuzzerTracePC.cpp - PC tracing--------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Trace PCs.
// This module implements __sanitizer_cov_trace_pc, a callback required
// for -fsanitize-coverage=trace-pc instrumentation.
//
//===----------------------------------------------------------------------===//
#include "FuzzerInternal.h"
namespace fuzzer {
static size_t PreviouslyComputedPCHash;
static ValueBitMap CurrentPCMap;
// Merges CurrentPCMap into M, returns the number of new bits.
size_t PCMapMergeFromCurrent(ValueBitMap &M) {
if (!PreviouslyComputedPCHash)
return 0;
PreviouslyComputedPCHash = 0;
return M.MergeFrom(CurrentPCMap);
}
static void HandlePC(uint32_t PC) {
// We take 12 bits of PC and mix it with the previous PCs.
uintptr_t Next = (PreviouslyComputedPCHash << 5) ^ (PC & 4095);
CurrentPCMap.AddValue(Next);
PreviouslyComputedPCHash = Next;
}
} // namespace fuzzer
extern "C" {
__attribute__((visibility("default")))
void __sanitizer_cov_trace_pc() {
fuzzer::HandlePC(static_cast<uint32_t>(
reinterpret_cast<uintptr_t>(__builtin_return_address(0))));
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_pc_indir(int *) {
// Stub to allow linking with code built with
// -fsanitize=indirect-calls,trace-pc.
// This isn't used currently.
}
}
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