[libFuzzer] Set -experimental_len_control=1000 as default.

Summary:
Experiments using
https://github.com/google/fuzzer-test-suite/tree/master/engine-comparison
show a significant increase in coverage and reduction in corpus size
with this option enabled.

Addresses https://llvm.org/pr36371.

Reviewers: kcc

Reviewed By: kcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D42932

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@325050 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerLoop.cpp b/FuzzerLoop.cpp
index 7366f69..7a3ce34 100644
--- a/FuzzerLoop.cpp
+++ b/FuzzerLoop.cpp
@@ -755,15 +755,15 @@
       break;
 
     // Update TmpMaxMutationLen
-    if (Options.ExperimentalLenControl) {
+    if (Options.LenControl) {
       if (TmpMaxMutationLen < MaxMutationLen &&
           TotalNumberOfRuns - LastCorpusUpdateRun >
-              Options.ExperimentalLenControl * Log(TmpMaxMutationLen)) {
+              Options.LenControl * Log(TmpMaxMutationLen)) {
         TmpMaxMutationLen =
             Min(MaxMutationLen, TmpMaxMutationLen + Log(TmpMaxMutationLen));
         if (TmpMaxMutationLen <= MaxMutationLen)
           Printf("#%zd\tTEMP_MAX_LEN: %zd (%zd %zd)\n", TotalNumberOfRuns,
-                 TmpMaxMutationLen, Options.ExperimentalLenControl,
+                 TmpMaxMutationLen, Options.LenControl,
                  LastCorpusUpdateRun);
         LastCorpusUpdateRun = TotalNumberOfRuns;
       }