[libfuzzer] print_new_cov_pcs experimental option.

Differential Revision: http://reviews.llvm.org/D15901

llvm-svn: 256882

5 files changed, 28 insertions, 1 deletions

diff --git a/llvm/lib/Fuzzer/FuzzerDriver.cpp b/llvm/lib/Fuzzer/FuzzerDriver.cpp
index dc5f8babbfe..e8c117ef608 100644
--- a/llvm/lib/Fuzzer/FuzzerDriver.cpp
+++ b/llvm/lib/Fuzzer/FuzzerDriver.cpp
@@ -281,6 +281,7 @@ int FuzzerDriver(const std::vector<std::string> &Args,
   if (Flags.verbosity > 0 && !Dictionary.empty())
     Printf("Dictionary: %zd entries\n", Dictionary.size());
   Options.SaveArtifacts = !Flags.test_single_input;
+  Options.PrintNewCovPcs = Flags.print_new_cov_pcs;
 
   Fuzzer F(USF, Options);
 
diff --git a/llvm/lib/Fuzzer/FuzzerFlags.def b/llvm/lib/Fuzzer/FuzzerFlags.def
index c2b506c3c8a..6d98f66ef9c 100644
--- a/llvm/lib/Fuzzer/FuzzerFlags.def
+++ b/llvm/lib/Fuzzer/FuzzerFlags.def
@@ -72,3 +72,5 @@ FUZZER_FLAG_STRING(exact_artifact_path,
 FUZZER_FLAG_INT(drill, 0, "Experimental: fuzz using a single unit as the seed "
                           "corpus, then merge with the initial corpus")
 FUZZER_FLAG_INT(output_csv, 0, "Enable pulse output in CSV format.")
+FUZZER_FLAG_INT(print_new_cov_pcs, 0, "If 1, print out new covered pcs.")
+
diff --git a/llvm/lib/Fuzzer/FuzzerInternal.h b/llvm/lib/Fuzzer/FuzzerInternal.h
index e96a4bc35fe..17a2cae94a5 100644
--- a/llvm/lib/Fuzzer/FuzzerInternal.h
+++ b/llvm/lib/Fuzzer/FuzzerInternal.h
@@ -97,6 +97,7 @@ class Fuzzer {
     bool SaveArtifacts = true;
     bool PrintNEW = true;  // Print a status line when new units are found;
     bool OutputCSV = false;
+    bool PrintNewCovPcs = false;
   };
   Fuzzer(UserSuppliedFuzzer &USF, FuzzingOptions Options);
   void AddToCorpus(const Unit &U) { Corpus.push_back(U); }
@@ -188,6 +189,7 @@ class Fuzzer {
   long EpochOfLastReadOfOutputCorpus = 0;
   size_t LastRecordedBlockCoverage = 0;
   size_t LastRecordedCallerCalleeCoverage = 0;
+  size_t LastCoveragePcBufferLen = 0;
 };
 
 class SimpleUserSuppliedFuzzer: public UserSuppliedFuzzer {
diff --git a/llvm/lib/Fuzzer/FuzzerLoop.cpp b/llvm/lib/Fuzzer/FuzzerLoop.cpp
index 7ea82f4f15d..0b1d9d9686a 100644
--- a/llvm/lib/Fuzzer/FuzzerLoop.cpp
+++ b/llvm/lib/Fuzzer/FuzzerLoop.cpp
@@ -31,6 +31,8 @@ void __sanitizer_set_death_callback(void (*callback)(void));
 __attribute__((weak)) size_t __sanitizer_get_number_of_counters();
 __attribute__((weak))
 uintptr_t __sanitizer_update_counter_bitset_and_clear_counters(uint8_t *bitset);
+__attribute__((weak)) uintptr_t
+__sanitizer_get_coverage_pc_buffer(uintptr_t **data);
 }
 
 namespace fuzzer {
@@ -249,7 +251,21 @@ void Fuzzer::ExecuteCallback(const Unit &U) {
 
 size_t Fuzzer::RecordBlockCoverage() {
   CHECK_WEAK_API_FUNCTION(__sanitizer_get_total_unique_coverage);
-  return LastRecordedBlockCoverage = __sanitizer_get_total_unique_coverage();
+  uintptr_t PrevCoverage = LastRecordedBlockCoverage;
+  LastRecordedBlockCoverage = __sanitizer_get_total_unique_coverage();
+
+  if (PrevCoverage == LastRecordedBlockCoverage || !Options.PrintNewCovPcs)
+    return LastRecordedBlockCoverage;
+
+  uintptr_t PrevBufferLen = LastCoveragePcBufferLen;
+  uintptr_t *CoverageBuf;
+  LastCoveragePcBufferLen = __sanitizer_get_coverage_pc_buffer(&CoverageBuf);
+  assert(CoverageBuf);
+  for (size_t i = PrevBufferLen; i < LastCoveragePcBufferLen; ++i) {
+    Printf("0x%x\n", CoverageBuf[i]);
+  }
+
+  return LastRecordedBlockCoverage;
 }
 
 size_t Fuzzer::RecordCallerCalleeCoverage() {
diff --git a/llvm/lib/Fuzzer/test/fuzzer.test b/llvm/lib/Fuzzer/test/fuzzer.test
index 810410df6fc..150fc7202b0 100644
--- a/llvm/lib/Fuzzer/test/fuzzer.test
+++ b/llvm/lib/Fuzzer/test/fuzzer.test
@@ -30,3 +30,9 @@ RUN:     LLVMFuzzer-SimpleDictionaryTest                    -seed=1 -runs=100000
 
 RUN: not LLVMFuzzer-UninstrumentedTest-Uninstrumented 2>&1 | FileCheck %s --check-prefix=UNINSTRUMENTED
 UNINSTRUMENTED: ERROR: __sanitizer_set_death_callback is not defined. Exiting.
+
+RUN: LLVMFuzzer-SimpleTest -print_new_cov_pcs=1 2>&1 | FileCheck %s --check-prefix=PCS
+PCS:{{^0x[a-f0-9]+}}
+PCS:NEW
+PCS:BINGO
+