[libFuzzer] extend -print_coverage to also print uncovered lines, functions, and files.

Example of output:
COVERAGE:
COVERED: in DSO2(int) /pathto/DSO2.cpp:6
COVERED: in DSO2(int) /pathto/DSO2.cpp:8
COVERED: in DSO1(int) /pathto/DSO1.cpp:6
COVERED: in DSO1(int) /pathto/DSO1.cpp:8
COVERED: in LLVMFuzzerTestOneInput /pathto/DSOTestMain.cpp:16
COVERED: in LLVMFuzzerTestOneInput /pathto/DSOTestMain.cpp:19
COVERED: in LLVMFuzzerTestOneInput /pathto/DSOTestMain.cpp:25
COVERED: in LLVMFuzzerTestOneInput /pathto/DSOTestMain.cpp:26
MODULE_WITH_COVERAGE: /pathto/libLLVMFuzzer-DSO1.so
UNCOVERED_LINE: in DSO1(int) /pathto/DSO1.cpp:9
UNCOVERED_FUNC: in Uncovered1()
MODULE_WITH_COVERAGE: /pathto/libLLVMFuzzer-DSO2.so
UNCOVERED_LINE: in DSO2(int) /pathto/DSO2.cpp:9
UNCOVERED_FUNC: in Uncovered2()
MODULE_WITH_COVERAGE: /pathto/LLVMFuzzer-DSOTest
UNCOVERED_LINE: in LLVMFuzzerTestOneInput /pathto/DSOTestMain.cpp:21
UNCOVERED_LINE: in LLVMFuzzerTestOneInput /pathto/DSOTestMain.cpp:27
UNCOVERED_FILE: /pathto/DSOTestExtra.cpp

Several things are not perfect here:
* we are using objdump+awk instead of sancov because sancov does not support DSOs yet.
* this breaks in the presence of ASAN_OPTIONS=strip_path_prefix=...
  (need to implement another API to get the module name by PC)

llvm-svn: 284554

4 files changed, 24 insertions, 6 deletions

diff --git a/llvm/lib/Fuzzer/test/DSO1.cpp b/llvm/lib/Fuzzer/test/DSO1.cpp
index c362593f779..4a293890f4b 100644
--- a/llvm/lib/Fuzzer/test/DSO1.cpp
+++ b/llvm/lib/Fuzzer/test/DSO1.cpp
@@ -9,3 +9,4 @@ int DSO1(int a) {
   return 1;
 }
 
+void Uncovered1() { }
diff --git a/llvm/lib/Fuzzer/test/DSO2.cpp b/llvm/lib/Fuzzer/test/DSO2.cpp
index 46c80e4b6fe..04b308d193a 100644
--- a/llvm/lib/Fuzzer/test/DSO2.cpp
+++ b/llvm/lib/Fuzzer/test/DSO2.cpp
@@ -9,3 +9,4 @@ int DSO2(int a) {
   return 1;
 }
 
+void Uncovered2() {}
diff --git a/llvm/lib/Fuzzer/test/DSOTestMain.cpp b/llvm/lib/Fuzzer/test/DSOTestMain.cpp
index 49cd185e97d..3e225d88612 100644
--- a/llvm/lib/Fuzzer/test/DSOTestMain.cpp
+++ b/llvm/lib/Fuzzer/test/DSOTestMain.cpp
@@ -11,17 +11,21 @@ extern int DSO1(int a);
 extern int DSO2(int a);
 extern int DSOTestExtra(int a);
 
+static volatile int *nil = 0;
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
-  if (Size < sizeof(int) * 3) return 0;
   int x, y, z;
-  memcpy(&x, Data + 0 * sizeof(int), sizeof(int));
-  memcpy(&y, Data + 1 * sizeof(int), sizeof(int));
-  memcpy(&z, Data + 2 * sizeof(int), sizeof(int));
-  int sum = DSO1(x) + DSO2(y) + DSOTestExtra(z);
+  if (Size < sizeof(int) * 3) {
+    x = y = z = 0;
+  } else {
+    memcpy(&x, Data + 0 * sizeof(int), sizeof(int));
+    memcpy(&y, Data + 1 * sizeof(int), sizeof(int));
+    memcpy(&z, Data + 2 * sizeof(int), sizeof(int));
+  }
+  int sum = DSO1(x) + DSO2(y) + (z ? DSOTestExtra(z) : 0);
   if (sum == 3) {
     fprintf(stderr, "BINGO %d %d %d\n", x, y, z);
-    exit(1);
+    *nil = 0;
   }
   return 0;
 }
diff --git a/llvm/lib/Fuzzer/test/coverage.test b/llvm/lib/Fuzzer/test/coverage.test
index f6b43048417..b41a262c462 100644
--- a/llvm/lib/Fuzzer/test/coverage.test
+++ b/llvm/lib/Fuzzer/test/coverage.test
@@ -4,3 +4,15 @@ CHECK-DAG: COVERED: {{.*}}in LLVMFuzzerTestOneInput {{.*}}NullDerefTest.cpp:14
 CHECK-DAG: COVERED: {{.*}}in LLVMFuzzerTestOneInput {{.*}}NullDerefTest.cpp:16
 CHECK-DAG: COVERED: {{.*}}in LLVMFuzzerTestOneInput {{.*}}NullDerefTest.cpp:19
 RUN: not LLVMFuzzer-NullDerefTest-TracePC -print_coverage=1 2>&1 | FileCheck %s
+
+RUN: LLVMFuzzer-DSOTest -print_coverage=1 -runs=0 2>&1 | FileCheck %s --check-prefix=DSO
+DSO: COVERAGE:
+DSO-DAG: COVERED:{{.*}}DSO1{{.*}}DSO1.cpp
+DSO-DAG: COVERED:{{.*}}DSO2{{.*}}DSO2.cpp
+DSO-DAG: COVERED:{{.*}}LLVMFuzzerTestOneInput{{.*}}DSOTestMain
+DSO-DAG: UNCOVERED_LINE:{{.*}}DSO1{{.*}}DSO1.cpp
+DSO-DAG: UNCOVERED_LINE:{{.*}}DSO2{{.*}}DSO2.cpp
+DSO-DAG: UNCOVERED_FUNC: in Uncovered1
+DSO-DAG: UNCOVERED_FUNC: in Uncovered2
+DSO-DAG: UNCOVERED_LINE: in LLVMFuzzerTestOneInput
+DSO-DAG: UNCOVERED_FILE:{{.*}}DSOTestExtra.cpp