[libFuzzer] Fix denominator in the "inputs have DFT" log line.

Summary:
The number of "inputs have the Data Flow Trace" cannot be greater than
the number of inputs touching the focus function. The existing message is rather
confusing as the same log would mention a greater total number of traces a few
lines above.

Reviewers: kcc, metzman

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D74779

compiler-rt/lib/fuzzer/FuzzerLoop.cpp

@@ -770,12 +770,14 @@ void Fuzzer::ReadAndExecuteSeedCorpora(Vector<SizedFile> &CorporaFiles) {
   }
 
   PrintStats("INITED");
-  if (!Options.FocusFunction.empty())
+  if (!Options.FocusFunction.empty()) {
     Printf("INFO: %zd/%zd inputs touch the focus function\n",
            Corpus.NumInputsThatTouchFocusFunction(), Corpus.size());
-  if (!Options.DataFlowTrace.empty())
-    Printf("INFO: %zd/%zd inputs have the Data Flow Trace\n",
-           Corpus.NumInputsWithDataFlowTrace(), Corpus.size());
+    if (!Options.DataFlowTrace.empty())
+      Printf("INFO: %zd/%zd inputs have the Data Flow Trace\n",
+             Corpus.NumInputsWithDataFlowTrace(),
+             Corpus.NumInputsThatTouchFocusFunction());
+  }
 
   if (Corpus.empty() && Options.MaxNumberOfRuns) {
     Printf("ERROR: no interesting inputs were found. "

compiler-rt/test/fuzzer/dataflow.test

@@ -107,11 +107,13 @@ RUN: rm -rf %t/OUT
 RUN: %t-ThreeFunctionsTest  -collect_data_flow=%t-ThreeFunctionsTestDF -data_flow_trace=%t/OUT %t/IN
 RUN: %t-ThreeFunctionsTest -data_flow_trace=%t/OUT -runs=0 -focus_function=Func2 %t/IN 2>&1 | FileCheck %s --check-prefix=USE_DATA_FLOW_TRACE
 
-
 USE_DATA_FLOW_TRACE: INFO: DataFlowTrace: reading from {{.*}}/OUT
 USE_DATA_FLOW_TRACE: d28cb407e8e1a702c72d25473f0553d3ec172262 => |000001|
 USE_DATA_FLOW_TRACE: INFO: DataFlowTrace: 6 trace files, 3 functions, 1 traces with focus function
 USE_DATA_FLOW_TRACE: INFO: Focus function is set to 'Func2'
+USE_DATA_FLOW_TRACE: INITED
+USE_DATA_FLOW_TRACE: INFO: 2/6 inputs touch the focus function
+USE_DATA_FLOW_TRACE: INFO: 1/2 inputs have the Data Flow Trace
 
 # Test that we can run collect_data_flow on a long input (>2**16 bytes)
 RUN: printf "%0.sA" {1..150001} > %t/IN/very_long_input