8036091: compiler/membars/DekkerTest.java fails with -XX:CICompilerCount=1

Summary: Start test with -XX:-TieredCompilation so that one compiler thread works
Reviewed-by: kvn, twisti

src/share/vm/runtime/arguments.cpp

@@ -2463,7 +2463,7 @@ bool Arguments::check_vm_args_consistency() {
 #endif
 
   // TieredCompilation needs at least 2 compiler threads.
-  const int num_min_compiler_threads = (TieredCompilation) ? 2 : 1;
+  const int num_min_compiler_threads = (TieredCompilation && (TieredStopAtLevel >= CompLevel_full_optimization)) ? 2 : 1;
   status &=verify_min_value(CICompilerCount, num_min_compiler_threads, "CICompilerCount");
 
   return status;

test/compiler/membars/DekkerTest.java

@@ -25,9 +25,9 @@
  * @test
  * @bug 8007898
  * @summary Incorrect optimization of Memory Barriers in Matcher::post_store_load_barrier().
- * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:CICompilerCount=1 -XX:+StressGCM -XX:+StressLCM DekkerTest
- * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:CICompilerCount=1 -XX:+StressGCM -XX:+StressLCM DekkerTest
- * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:CICompilerCount=1 -XX:+StressGCM -XX:+StressLCM DekkerTest
+ * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:CICompilerCount=1 -XX:-TieredCompilation -XX:+StressGCM -XX:+StressLCM DekkerTest
+ * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:CICompilerCount=1 -XX:-TieredCompilation -XX:+StressGCM -XX:+StressLCM DekkerTest
+ * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:CICompilerCount=1 -XX:-TieredCompilation -XX:+StressGCM -XX:+StressLCM DekkerTest
  * @author Martin Doerr martin DOT doerr AT sap DOT com
  *
  * Run 3 times since the failure is intermittent.