8316702: Only evaluate buffer when IGVPrintLevelOption >= 5

Reviewed-by: chagedorn, thartmann

Author: Xin Liu

src/hotspot/share/opto/compile.cpp

@@ -5127,7 +5127,7 @@ bool Compile::should_print_phase(CompilerPhaseType cpt) {
   return false;
 }
 
-bool Compile::should_print_igv(int level) {
+bool Compile::should_print_igv(const int level) {
 #ifndef PRODUCT
   if (PrintIdealGraphLevel < 0) { // disabled by the user
     return false;

src/hotspot/share/opto/parse2.cpp

@@ -2779,13 +2779,14 @@ void Parse::do_one_bytecode() {
   }
 
 #ifndef PRODUCT
-  if (C->should_print_igv(1)) {
+  constexpr int perBytecode = 5;
+  if (C->should_print_igv(perBytecode)) {
     IdealGraphPrinter* printer = C->igv_printer();
     char buffer[256];
     jio_snprintf(buffer, sizeof(buffer), "Bytecode %d: %s", bci(), Bytecodes::name(bc()));
     bool old = printer->traverse_outs();
     printer->set_traverse_outs(true);
-    printer->print_method(buffer, 5);
+    printer->print_method(buffer, perBytecode);
     printer->set_traverse_outs(old);
   }
 #endif