pkg/fuzzer: deflake against new signal

We don't want to reach just any stable signal, we know the specific new
signal that we target. The previous approach might have reduced the
efficiency of the new deflake() approach.

4 files changed, 22 insertions, 4 deletions

diff --git a/pkg/fuzzer/job.go b/pkg/fuzzer/job.go
index 2086016bf..5f734a945 100644
--- a/pkg/fuzzer/job.go
+++ b/pkg/fuzzer/job.go
@@ -186,11 +186,12 @@ func (job *triageJob) deflake(exec func(job, *Request) *Result, stat *stats.Val,
 	)
 	signals := make([]signal.Signal, needRuns)
 	for i := 0; i < maxRuns; i++ {
-		if signals[needRuns-1].Len() > 0 {
-			// We've already got signal common to needRuns.
+		if job.newSignal.IntersectsWith(signals[needRuns-1]) {
+			// We already have the right deflaked signal.
 			break
 		}
-		if left := maxRuns - i; left < needRuns && signals[needRuns-left-1].Len() == 0 {
+		if left := maxRuns - i; left < needRuns &&
+			!job.newSignal.IntersectsWith(signals[needRuns-left-1]) {
 			// There's no chance to get coverage common to needRuns.
 			break
 		}
diff --git a/pkg/fuzzer/job_test.go b/pkg/fuzzer/job_test.go
index 70efc0bb6..cdf46186d 100644
--- a/pkg/fuzzer/job_test.go
+++ b/pkg/fuzzer/job_test.go
@@ -24,7 +24,7 @@ func TestDeflakeFail(t *testing.T) {
 	testJob := &triageJob{
 		p:         prog,
 		info:      ipc.CallInfo{},
-		newSignal: signal.FromRaw([]uint32{0, 1, 2}, 0),
+		newSignal: signal.FromRaw([]uint32{0, 1, 2, 3, 4}, 0),
 	}
 
 	run := 0
diff --git a/pkg/signal/signal.go b/pkg/signal/signal.go
index f7f7899b2..48686de54 100644
--- a/pkg/signal/signal.go
+++ b/pkg/signal/signal.go
@@ -92,6 +92,15 @@ func (s Signal) DiffRaw(raw []uint32, prio uint8) Signal {
 	return res
 }
 
+func (s Signal) IntersectsWith(other Signal) bool {
+	for e, p := range s {
+		if p1, ok := other[e]; ok && p1 >= p {
+			return true
+		}
+	}
+	return false
+}
+
 func (s Signal) Intersection(s1 Signal) Signal {
 	if s1.Empty() {
 		return nil
diff --git a/pkg/signal/signal_test.go b/pkg/signal/signal_test.go
index f5582698f..efd53d2ea 100644
--- a/pkg/signal/signal_test.go
+++ b/pkg/signal/signal_test.go
@@ -31,3 +31,11 @@ func TestSubtract(t *testing.T) {
 	base.Subtract(FromRaw([]uint32{1}, 0))
 	assert.Equal(t, 3, base.Len())
 }
+
+func TestIntersectsWith(t *testing.T) {
+	base := FromRaw([]uint32{0, 1, 2, 3, 4}, 1)
+	assert.True(t, base.IntersectsWith(FromRaw([]uint32{0, 5, 10}, 1)))
+	assert.False(t, base.IntersectsWith(FromRaw([]uint32{5, 10, 15}, 1)))
+	// The other signal has a lower priority.
+	assert.False(t, base.IntersectsWith(FromRaw([]uint32{0, 1, 2}, 0)))
+}