[libFuzzer] remove the experimental support for clang coverage instrumentation. This mode has not been used and our experiments with https://github.com/google/fuzzer-test-suite show that this signal is weaker than the SanitizerCoverage

llvm-svn: 332034

compiler-rt/lib/fuzzer/CMakeLists.txt

@@ -1,5 +1,4 @@
 set(LIBFUZZER_SOURCES
-  FuzzerClangCounters.cpp
   FuzzerCrossOver.cpp
   FuzzerDriver.cpp
   FuzzerExtFunctionsDlsym.cpp

compiler-rt/lib/fuzzer/FuzzerClangCounters.cpp

@@ -1,49 +0,0 @@
-//===- 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;
-}
-}

compiler-rt/lib/fuzzer/FuzzerDefs.h

@@ -186,10 +186,6 @@ uint8_t *ExtraCountersBegin();
 uint8_t *ExtraCountersEnd();
 void ClearExtraCounters();
 
-uint64_t *ClangCountersBegin();
-uint64_t *ClangCountersEnd();
-void ClearClangCounters();
-
 }  // namespace fuzzer
 
 #endif  // LLVM_FUZZER_DEFS_H

compiler-rt/lib/fuzzer/FuzzerDriver.cpp

@@ -616,7 +616,6 @@ int FuzzerDriver(int *argc, char ***argv, UserCallback Callback) {
   Options.PrintCorpusStats = Flags.print_corpus_stats;
   Options.PrintCoverage = Flags.print_coverage;
   Options.DumpCoverage = Flags.dump_coverage;
-  Options.UseClangCoverage = Flags.use_clang_coverage;
   Options.UseFeatureFrequency = Flags.use_feature_frequency;
   if (Flags.exit_on_src_pos)
     Options.ExitOnSrcPos = Flags.exit_on_src_pos;

compiler-rt/lib/fuzzer/FuzzerFlags.def

@@ -149,5 +149,5 @@ FUZZER_FLAG_INT(ignore_remaining_args, 0, "If 1, ignore all arguments passed "
 FUZZER_FLAG_STRING(run_equivalence_server, "Experimental")
 FUZZER_FLAG_STRING(use_equivalence_server, "Experimental")
 FUZZER_FLAG_INT(analyze_dict, 0, "Experimental")
-FUZZER_FLAG_INT(use_clang_coverage, 0, "Experimental")
+FUZZER_DEPRECATED_FLAG(use_clang_coverage)
 FUZZER_FLAG_INT(use_feature_frequency, 0, "Experimental/internal")

compiler-rt/lib/fuzzer/FuzzerLoop.cpp

@@ -149,7 +149,6 @@ Fuzzer::Fuzzer(UserCallback CB, InputCorpus &Corpus, MutationDispatcher &MD,
     EF->__sanitizer_install_malloc_and_free_hooks(MallocHook, FreeHook);
   TPC.SetUseCounters(Options.UseCounters);
   TPC.SetUseValueProfile(Options.UseValueProfile);
-  TPC.SetUseClangCoverage(Options.UseClangCoverage);
 
   if (Options.Verbosity)
     TPC.PrintModuleInfo();

compiler-rt/lib/fuzzer/FuzzerOptions.h

@@ -53,7 +53,6 @@ struct FuzzingOptions {
   bool PrintCorpusStats = false;
   bool PrintCoverage = false;
   bool DumpCoverage = false;
-  bool UseClangCoverage = false;
   bool DetectLeaks = true;
   int PurgeAllocatorIntervalSec = 1;
   int UseFeatureFrequency = false;

compiler-rt/lib/fuzzer/FuzzerTracePC.cpp

@@ -132,9 +132,6 @@ void TracePC::PrintModuleInfo() {
       _Exit(1);
     }
   }
-  if (size_t NumClangCounters = ClangCountersEnd() - ClangCountersBegin())
-    Printf("INFO: %zd Clang Coverage Counters\n", NumClangCounters);
-
   if (size_t NumExtraCounters = ExtraCountersEnd() - ExtraCountersBegin())
     Printf("INFO: %zd Extra Counters\n", NumExtraCounters);
 }
@@ -185,13 +182,6 @@ void TracePC::UpdateObservedPCs() {
       }
     }
   }
-  if (size_t NumClangCounters =
-      ClangCountersEnd() - ClangCountersBegin()) {
-    auto P = ClangCountersBegin();
-    for (size_t Idx = 0; Idx < NumClangCounters; Idx++)
-      if (P[Idx])
-        ObservePC((uintptr_t)Idx);
-  }
 
   for (size_t i = 0, N = Min(CoveredFuncs.size(), NumPrintNewFuncs); i < N; i++) {
     Printf("\tNEW_FUNC[%zd/%zd]: ", i, CoveredFuncs.size());

compiler-rt/lib/fuzzer/FuzzerTracePC.h

@@ -80,7 +80,6 @@ class TracePC {
   template <class T> void HandleCmp(uintptr_t PC, T Arg1, T Arg2);
   size_t GetTotalPCCoverage();
   void SetUseCounters(bool UC) { UseCounters = UC; }
-  void SetUseClangCoverage(bool UCC) { UseClangCoverage = UCC; }
   void SetUseValueProfile(bool VP) { UseValueProfile = VP; }
   void SetPrintNewPCs(bool P) { DoPrintNewPCs = P; }
   void SetPrintNewFuncs(size_t P) { NumPrintNewFuncs = P; }
@@ -93,8 +92,6 @@ class TracePC {
       memset(Counters(), 0, GetNumPCs());
     ClearExtraCounters();
     ClearInlineCounters();
-    if (UseClangCoverage)
-      ClearClangCounters();
   }
 
   void ClearInlineCounters();
@@ -135,7 +132,6 @@ class TracePC {
 private:
   bool UseCounters = false;
   bool UseValueProfile = false;
-  bool UseClangCoverage = false;
   bool DoPrintNewPCs = false;
   size_t NumPrintNewFuncs = 0;
 
@@ -251,18 +247,6 @@ void TracePC::CollectFeatures(Callback HandleFeature) const {
     }
   }
 
-  if (size_t NumClangCounters = ClangCountersEnd() - ClangCountersBegin()) {
-    auto P = ClangCountersBegin();
-    for (size_t Idx = 0; Idx < NumClangCounters; Idx++)
-      if (auto Cnt = P[Idx]) {
-        if (UseCounters)
-          HandleFeature(FirstFeature + Idx * 8 + CounterToFeature(Cnt));
-        else
-          HandleFeature(FirstFeature + Idx);
-      }
-    FirstFeature += NumClangCounters;
-  }
-
   ForEachNonZeroByte(ExtraCountersBegin(), ExtraCountersEnd(), FirstFeature,
                      Handle8bitCounter);
   FirstFeature += (ExtraCountersEnd() - ExtraCountersBegin()) * 8;

compiler-rt/test/fuzzer/fprofile-instr-generate.test

@@ -1,7 +0,0 @@
-# Test libFuzzer + -fprofile-instr-generate
-REQUIRES: linux
-RUN: %cpp_compiler %S/SimpleTest.cpp -fsanitize-coverage=0 -fprofile-instr-generate -o %t-SimpleTest-fprofile-instr-generate
-CHECK-NOT: INFO: Loaded 1 modules
-CHECK: INFO: {{.*}} Clang Coverage Counters
-CHECK: BINGO
-RUN: not %t-SimpleTest-fprofile-instr-generate -runs=1000000 -seed=1 -use_clang_coverage=1 2>&1 | FileCheck %s