[compiler-rt][nsan] Add test for NaN dectection

Author: cseslowpoke

compiler-rt/test/nsan/nan.cpp

@@ -0,0 +1,22 @@
+// RUN: %clangxx_nsan -O0 -g %s -o %t
+// RUN: NSAN_OPTIONS=check_nan=true %run %t 2>&1 | FileCheck %s
+
+
+#include<cmath>
+#include<cstdio>
+
+// This function returns a NaN value for triggering the NaN detection.
+__attribute__((noinline))  
+float ReturnNaN() {
+  float ret = 0.0 / 0.0;
+  return ret;
+  // CHECK: WARNING: NumericalStabilitySanitizer: NaN detected
+}
+
+
+int main() {
+  float val = ReturnNaN();
+  printf("val: %f\n", val);
+  // CHECK: WARNING: NumericalStabilitySanitizer: NaN detected
+  return 0;
+}