is_null -> is_empty

Author: shipilev

src/hotspot/share/compiler/compileTask.cpp

@@ -181,7 +181,7 @@ CompileTask* CompileTask::select_for_compilation() {
   }
 
   // Capture method holder by strong handle to avoid unloading during compilation.
-  if (!_method_unload_blocker_weak.is_null()) {
+  if (!_method_unload_blocker_weak.is_empty()) {
     assert(_method_unload_blocker_weak.peek() != nullptr, "Should not be cleared");
     assert(_method->method_holder()->is_loader_alive(), "Should be alive");
     assert(_method_unload_blocker_strong.is_empty(), "Should be empty");
@@ -190,7 +190,7 @@ CompileTask* CompileTask::select_for_compilation() {
 
   // See if hot method holder is still alive. If so, capture it by strong handle.
   // If not, reset it to nullptr, so downstream logging code does not crash.
-  if (!_hot_method_unload_blocker_weak.is_null()) {
+  if (!_hot_method_unload_blocker_weak.is_empty()) {
     if (_hot_method_unload_blocker_weak.peek() != nullptr) {
       assert(_hot_method->method_holder()->is_loader_alive(), "Should be alive");
       assert(_hot_method_unload_blocker_strong.is_empty(), "Should be empty");
@@ -216,7 +216,7 @@ void CompileTask::mark_on_stack() {
 
 bool CompileTask::is_unloaded() const {
   // Unloaded if weakly referenced blocker was set, but now had been cleared by GC.
-  return !_method_unload_blocker_weak.is_null() && _method_unload_blocker_weak.peek() == nullptr;
+  return !_method_unload_blocker_weak.is_empty() && _method_unload_blocker_weak.peek() == nullptr;
 }
 
 // RedefineClasses support