Add runtime test for -fsanitizer-coverage=control-flow

[MaskRay]

The test change should be merged into the patch which introduces the feature.

[vitalybuka]

compiler-rt/test/sanitizer_common/TestCases/sanitizer_coverage_control_flow.cpp

40

please add a new line

[vitalybuka]

In D133388#3773438, @MaskRay wrote:

The test change should be merged into the patch which introduces the feature.

I asked to extracted it suspecting that this will need few reverts before making green some unusual bots

[Navidem]

Use FileCheck

[Navidem]

Fix new line

[Navidem]

Adjust test to use __sanitizer_cov_cfs_init

[vitalybuka]

compiler-rt/test/sanitizer_common/TestCases/sanitizer_coverage_control_flow.cpp

13

It's even better, using __sanitizer_cov_cfs_init

you actually can print out structure of the cfs_beg in some humane readable form

FN ###
  BLOCK ###
   BRACH ###
  BLOCK ###
  BLOCK ###

compiler-rt/test/sanitizer_common/TestCases/sanitizer_coverage_control_flow.cpp

+// Tests -fsanitize-coverage=control-flow.
+
+// REQUIRES: has_sancovcc,stable-runtime
+// UNSUPPORTED: i386-darwin, x86_64-darwin
+
+// RUN: %clangxx -O0 -std=c++11 -fsanitize-coverage=control-flow %s -o %t
+// RUN: llvm-objdump -s --section="__sancov_cfs" %t | FileCheck %s
+
+#include <cstdio>
+
+void foo(int recurse) {
+  if (recurse > 0)
+    foo(recurse - 1);
+}
+
+int main() {
+  int x = 10;
+  for (int i = 0; i < 10; i++) {
+    if (x > 5)
+      foo(x);
+  }
+
+  switch (x) {
+  case 5:
+    foo(x);
+    break;
+  case -5:
+    foo(-x);
+    break;
+
+  default:
+    break;
+  }
+  printf("Success!\n");
+  return 0;
+}
+
+// CHECK: Contents of section __sancov_cfs
+// TODO(navidem): make sure this is all to be checked for the collected control flow.