[sanitizers] rewriting test assuming assert() changes coverage.

[aizatsky]

Summary

On windows platform assert() call creates two distinct CFG edges
which are coverage-instrumented. Simply calling assert would
change coverage numbers on the platform.

[eugenis]

LGTM

test/asan/TestCases/coverage-pc-buffer.cc

 
 void assertNotZeroPcs(uintptr_t *buf, uintptr_t size) {
   assert(buf);
   for (uintptr_t i = 0; i < size; ++i)
     assert(buf[i]);
 }
 
 int main() {
+  {
     uintptr_t *buf = NULL;
     uintptr_t sz = __sanitizer_get_coverage_pc_buffer(&buf);
     assertNotZeroPcs(buf, sz);
     assert(sz);
+  }
 
+  {
+    uintptr_t *buf = NULL;
+    uintptr_t sz = __sanitizer_get_coverage_pc_buffer(&buf);
+    // call functions for the first time.
     foo();
     bar();
     uintptr_t *buf1 = NULL;
     uintptr_t sz1 = __sanitizer_get_coverage_pc_buffer(&buf1);
     assertNotZeroPcs(buf1, sz1);
     assert(buf1 == buf);
     assert(sz1 > sz);
+  }
+
+  {
+    uintptr_t *buf = NULL;
+    uintptr_t sz = __sanitizer_get_coverage_pc_buffer(&buf);
+    // second call shouldn't increase coverage.
+    bar();
+    uintptr_t *buf1 = NULL;
+    uintptr_t sz1 = __sanitizer_get_coverage_pc_buffer(&buf1);
+    assertNotZeroPcs(buf1, sz1);
+    assert(buf1 == buf);
+    assert(sz1 == sz);
+  }
 
+  {
+    uintptr_t *buf = NULL;
+    uintptr_t sz = __sanitizer_get_coverage_pc_buffer(&buf);
+    // reset coverage to 0.
     __sanitizer_reset_coverage();
-  uintptr_t *buf3 = NULL;
-  uintptr_t sz3 = __sanitizer_get_coverage_pc_buffer(&buf3);
-  assertNotZeroPcs(buf3, sz3);
-  assert(buf3 == buf);
-  assert(sz3 < sz1);
+    uintptr_t *buf1 = NULL;
+    uintptr_t sz1 = __sanitizer_get_coverage_pc_buffer(&buf1);
+    assertNotZeroPcs(buf1, sz1);
+    assert(buf1 == buf);
+    assert(sz1 < sz);
+  }
 }