8042431: compiler/7200264/TestIntVect.java fails with: Test Failed: AddVI 0 < 4

Summary: Define a new function that determines the minimum number of compiler threads for a particular platform/configuration.
Reviewed-by: kvn

src/share/vm/runtime/arguments.cpp

@@ -1145,6 +1145,32 @@ void Arguments::set_tiered_flags() {
   }
 }
 
+/**
+ * Returns the minimum number of compiler threads needed to run the JVM. The following
+ * configurations are possible.
+ *
+ * 1) The JVM is build using an interpreter only. As a result, the minimum number of
+ *    compiler threads is 0.
+ * 2) The JVM is build using the compiler(s) and tiered compilation is disabled. As
+ *    a result, either C1 or C2 is used, so the minimum number of compiler threads is 1.
+ * 3) The JVM is build using the compiler(s) and tiered compilation is enabled. However,
+ *    the option "TieredStopAtLevel < CompLevel_full_optimization". As a result, only
+ *    C1 can be used, so the minimum number of compiler threads is 1.
+ * 4) The JVM is build using the compilers and tiered compilation is enabled. The option
+ *    'TieredStopAtLevel = CompLevel_full_optimization' (the default value). As a result,
+ *    the minimum number of compiler threads is 2.
+ */
+int Arguments::get_min_number_of_compiler_threads() {
+#if !defined(COMPILER1) && !defined(COMPILER2) && !defined(SHARK)
+  return 0;   // case 1
+#else
+  if (!TieredCompilation || (TieredStopAtLevel < CompLevel_full_optimization)) {
+    return 1; // case 2 or case 3
+  }
+  return 2;   // case 4 (tiered)
+#endif
+}
+
 #if INCLUDE_ALL_GCS
 static void disable_adaptive_size_policy(const char* collector_name) {
   if (UseAdaptiveSizePolicy) {
@@ -2462,9 +2488,11 @@ bool Arguments::check_vm_args_consistency() {
   status &= verify_interval(SafepointPollOffset, 0, os::vm_page_size() - BytesPerWord, "SafepointPollOffset");
 #endif
 
-  // TieredCompilation needs at least 2 compiler threads.
-  const int num_min_compiler_threads = (TieredCompilation && (TieredStopAtLevel >= CompLevel_full_optimization)) ? 2 : CI_COMPILER_COUNT;
-  status &=verify_min_value(CICompilerCount, num_min_compiler_threads, "CICompilerCount");
+  int min_number_of_compiler_threads = get_min_number_of_compiler_threads();
+  // The default CICompilerCount's value is CI_COMPILER_COUNT.
+  assert(min_number_of_compiler_threads <= CI_COMPILER_COUNT, "minimum should be less or equal default number");
+  // Check the minimum number of compiler threads
+  status &=verify_min_value(CICompilerCount, min_number_of_compiler_threads, "CICompilerCount");
 
   return status;
 }

src/share/vm/runtime/arguments.hpp

@@ -327,6 +327,7 @@ class Arguments : AllStatic {
 
   // Tiered
   static void set_tiered_flags();
+  static int  get_min_number_of_compiler_threads();
   // CMS/ParNew garbage collectors
   static void set_parnew_gc_flags();
   static void set_cms_and_parnew_gc_flags();