[PATCH] D87476: [libFuzzer] Enable entropic by default.

[Matt Morehouse via Phabricator via llvm-commits]

morehouse created this revision.
morehouse added a reviewer: kcc.
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Entropic has performed at least on par with vanilla scheduling on
Clusterfuzz, and has shown a slight coverage improvement on FuzzBench:
https://www.fuzzbench.com/reports/2020-08-31/index.html


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87476

Files:
  compiler-rt/lib/fuzzer/FuzzerDriver.cpp
  compiler-rt/lib/fuzzer/FuzzerFlags.def
  compiler-rt/lib/fuzzer/FuzzerOptions.h


Index: compiler-rt/lib/fuzzer/FuzzerOptions.h
===================================================================
--- compiler-rt/lib/fuzzer/FuzzerOptions.h
+++ compiler-rt/lib/fuzzer/FuzzerOptions.h
@@ -46,7 +46,7 @@
   size_t MaxNumberOfRuns = -1L;
   int ReportSlowUnits = 10;
   bool OnlyASCII = false;
-  bool Entropic = false;
+  bool Entropic = true;
   size_t EntropicFeatureFrequencyThreshold = 0xFF;
   size_t EntropicNumberOfRarestFeatures = 100;
   bool EntropicScalePerExecTime = false;
Index: compiler-rt/lib/fuzzer/FuzzerFlags.def
===================================================================
--- compiler-rt/lib/fuzzer/FuzzerFlags.def
+++ compiler-rt/lib/fuzzer/FuzzerFlags.def
@@ -172,7 +172,7 @@
      "Fuzzing will focus on inputs that trigger calls to this function. "
      "If -focus_function=auto and -data_flow_trace is used, libFuzzer "
      "will choose the focus functions automatically.")
-FUZZER_FLAG_INT(entropic, 0, "Experimental. Enables entropic power schedule.")
+FUZZER_FLAG_INT(entropic, 1, "Enables entropic power schedule.")
 FUZZER_FLAG_INT(entropic_feature_frequency_threshold, 0xFF, "Experimental. If "
      "entropic is enabled, all features which are observed less often than "
      "the specified value are considered as rare.")
Index: compiler-rt/lib/fuzzer/FuzzerDriver.cpp
===================================================================
--- compiler-rt/lib/fuzzer/FuzzerDriver.cpp
+++ compiler-rt/lib/fuzzer/FuzzerDriver.cpp
@@ -767,16 +767,12 @@
   Options.EntropicNumberOfRarestFeatures =
       (size_t)Flags.entropic_number_of_rarest_features;
   Options.EntropicScalePerExecTime = Flags.entropic_scale_per_exec_time;
-  if (Options.Entropic) {
-    if (!Options.FocusFunction.empty()) {
-      Printf("ERROR: The parameters `--entropic` and `--focus_function` cannot "
-             "be used together.\n");
-      exit(1);
-    }
+  if (!Options.FocusFunction.empty())
+    Options.Entropic = false; // FocusFunction overrides entropic scheduling.
+  if (Options.Entropic)
     Printf("INFO: Running with entropic power schedule (0x%X, %d).\n",
            Options.EntropicFeatureFrequencyThreshold,
            Options.EntropicNumberOfRarestFeatures);
-  }
   struct EntropicOptions Entropic;
   Entropic.Enabled = Options.Entropic;
   Entropic.FeatureFrequencyThreshold =


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