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