[PATCH] D51455: [libFuzzer] Remove mutation stats and weighted mutation selection.

[Max Moroz via Phabricator via llvm-commits]

Dor1s created this revision.
Dor1s added reviewers: metzman, morehouse.
Herald added subscribers: Sanitizers, delcypher.

This was an experimental feature. After evaluating it with:

1. https://github.com/google/fuzzer-test-suite/tree/master/engine-comparison

2. enabling on real world fuzz targets running at ClusterFuzz and OSS-Fuzz

The following conclusions were made:

1. With fuzz targets that have reached a code coverage plateau, the feature does not improve libFuzzer's ability to discover new coverage and may actually negatively impact it.

2. With fuzz targets that have not yet reached a code coverage plateau, the feature might speed up new units discovery in some cases, but it is quite rare and hard to confirm with a high level on confidence.

Revert of https://reviews.llvm.org/D48054 and https://reviews.llvm.org/D49621.


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D51455

Files:
  lib/fuzzer/FuzzerDriver.cpp
  lib/fuzzer/FuzzerFlags.def
  lib/fuzzer/FuzzerLoop.cpp
  lib/fuzzer/FuzzerMutate.cpp
  lib/fuzzer/FuzzerMutate.h
  lib/fuzzer/FuzzerOptions.h
  test/fuzzer/fuzzer-mutationstats.test

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