[libFuzzer] Handle unstable edges by disregarding unstable edges

Summary:
Added a new mode within flag -handle_unstable for new unstable handling algorithm that does the following:
    When an edge is shown as unstable, copy to UnstableCounters the value 0.
    During ApplyUnstableCounters we copy back the value 0 to ModuleInline8bitCounters if the edge was unstable.

This way we would be ignoring completely features that were collected through non-determinism.
Unstable hits would be counted as if it never hit.

Reviewers: metzman, Dor1s, kcc, morehouse

Reviewed By: metzman, morehouse

Subscribers: delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D49684

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@337853 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 39 insertions, 0 deletions

diff --git a/test/fuzzer/handle-unstable.test b/test/fuzzer/handle-unstable.test
new file mode 100644
index 000000000..2116d9a5e
--- /dev/null
+++ b/test/fuzzer/handle-unstable.test
@@ -0,0 +1,39 @@
+RUN: %cpp_compiler %S/PrintUnstableStatsTest.cpp -o %t-HandleUnstableTest
+
+; Normal
+RUN: %run %t-HandleUnstableTest -print_coverage=1 -runs=100000 2>&1 | FileCheck %s --check-prefix=NORMAL
+NORMAL-DAG: det0()
+NORMAL-DAG: det1()
+NORMAL-DAG: det2()
+NORMAL-DAG: det3()
+NORMAL-DAG: det4()
+NORMAL-DAG: ini0()
+NORMAL-DAG: ini1()
+NORMAL-DAG: ini2()
+NORMAL-DAG: t0()
+NORMAL-DAG: t1()
+NORMAL-DAG: t2()
+NORMAL-DAG: t3()
+NORMAL-DAG: t4()
+
+; MinUnstable
+RUN: %run %t-HandleUnstableTest -print_coverage=1 -handle_unstable=1 -runs=100000 2>&1 | FileCheck %s --check-prefix=MIN
+MIN-NOT: ini0()
+MIN-NOT: ini1()
+MIN-NOT: ini2()
+MIN: det0()
+MIN: det1()
+MIN: det2()
+MIN: det3()
+MIN: det4()
+
+; ZeroUnstable
+RUN: %run %t-HandleUnstableTest -print_coverage=1 -handle_unstable=2 -runs=1 2>&1 | FileCheck %s --check-prefix=ZERO
+ZERO-NOT: ini0()
+ZERO-NOT: ini1()
+ZERO-NOT: ini2()
+ZERO: det0()
+ZERO: det1()
+ZERO: det2()
+ZERO: det3()
+ZERO: det4()