50 lines
1.9 KiB
C++
50 lines
1.9 KiB
C++
//===- FuzzerExtraCounters.cpp - Extra coverage counters ------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// Coverage counters from Clang's SourceBasedCodeCoverage.
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//===----------------------------------------------------------------------===//
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// Support for SourceBasedCodeCoverage is experimental:
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// * Works only for the main binary, not DSOs yet.
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// * Works only on Linux.
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// * Does not implement print_pcs/print_coverage yet.
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// * Is not fully evaluated for performance and sensitivity.
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// We expect large performance drop due to 64-bit counters,
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// and *maybe* better sensitivity due to more fine-grained counters.
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// Preliminary comparison on a single benchmark (RE2) shows
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// a bit worse sensitivity though.
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#include "FuzzerDefs.h"
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#if LIBFUZZER_LINUX
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__attribute__((weak)) extern uint64_t __start___llvm_prf_cnts;
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__attribute__((weak)) extern uint64_t __stop___llvm_prf_cnts;
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namespace fuzzer {
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uint64_t *ClangCountersBegin() { return &__start___llvm_prf_cnts; }
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uint64_t *ClangCountersEnd() { return &__stop___llvm_prf_cnts; }
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} // namespace fuzzer
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#else
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// TODO: Implement on Mac (if the data shows it's worth it).
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//__attribute__((visibility("hidden")))
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//extern uint64_t CountersStart __asm("section$start$__DATA$__llvm_prf_cnts");
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//__attribute__((visibility("hidden")))
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//extern uint64_t CountersEnd __asm("section$end$__DATA$__llvm_prf_cnts");
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namespace fuzzer {
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uint64_t *ClangCountersBegin() { return nullptr; }
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uint64_t *ClangCountersEnd() { return nullptr; }
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} // namespace fuzzer
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#endif
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namespace fuzzer {
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ATTRIBUTE_NO_SANITIZE_ALL
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void ClearClangCounters() { // hand-written memset, don't asan-ify.
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for (auto P = ClangCountersBegin(); P < ClangCountersEnd(); P++)
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*P = 0;
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}
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}
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