commit 37cbead8d91fbbaccad87ee4ea89a289265ba0b3
author Matt Morehouse <mascasa@google.com> Tue Sep 15 10:33:23 2020 -0700
committer Copybara-Service <copybara-worker@google.com> Thu Mar 25 23:21:33 2021 -0700
tree 1988583cd3c50c2ebcf98059b853d3657f8f3b02
parent c8e63c7a65be27d0e7ee51ba9d32348c8aeb13f3

[libFuzzer] Enable entropic by default.

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

Reviewed By: Dor1s

Differential Revision: https://reviews.llvm.org/D87476

GitOrigin-RevId: f3c2e0bcee64b0905addaefe9cd0c9ad4d20ac6f

FuzzerDriver.cpp

diff --git a/FuzzerDriver.cpp b/FuzzerDriver.cpp
index 57df123..83ef642 100644
--- a/FuzzerDriver.cpp
+++ b/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 =

FuzzerFlags.def

diff --git a/FuzzerFlags.def b/FuzzerFlags.def
index c9a787e..4d4841b 100644
--- a/FuzzerFlags.def
+++ b/FuzzerFlags.def
@@ -171,8 +171,9 @@
 FUZZER_FLAG_STRING(focus_function, "Experimental. "
      "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.")
+     "will choose the focus functions automatically. Disables -entropic when "
+     "specified.")
+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.")

FuzzerOptions.h

diff --git a/FuzzerOptions.h b/FuzzerOptions.h
index 706e1c6..20b810b 100644
--- a/FuzzerOptions.h
+++ b/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;