7121111: -server -Xcomp -XX:+TieredCompilation does not invoke C2 compiler

Summary: Exercise C2 more in tiered mode with Xcomp
Reviewed-by: kvn, never

src/share/vm/runtime/arguments.cpp

@@ -1000,6 +1000,13 @@ void Arguments::set_mode_flags(Mode mode) {
     UseInterpreter           = false;
     BackgroundCompilation    = false;
     ClipInlining             = false;
+    // Be much more aggressive in tiered mode with -Xcomp and exercise C2 more.
+    // We will first compile a level 3 version (C1 with full profiling), then do one invocation of it and
+    // compile a level 4 (C2) and then continue executing it.
+    if (TieredCompilation) {
+      Tier3InvokeNotifyFreqLog = 0;
+      Tier4InvocationThreshold = 0;
+    }
     break;
   }
 }