8209087: Clean up runtime code that compares 'this' to NULL

Remove 'this' to NULL comparisons from methods and check if calling objects of these methods could be NULL.

Reviewed-by: lfoltan, gziemski

src/hotspot/share/classfile/verificationType.cpp

@@ -172,7 +172,11 @@ void VerificationType::print_on(outputStream* st) const {
       } else if (is_uninitialized()) {
         st->print("uninitialized %d", bci());
       } else {
-        name()->print_value_on(st);
+        if (name() != NULL) {
+          name()->print_value_on(st);
+        } else {
+          st->print_cr("NULL");
+        }
       }
   }
 }

src/hotspot/share/oops/symbol.cpp

@@ -294,28 +294,20 @@ void Symbol::metaspace_pointers_do(MetaspaceClosure* it) {
 }
 
 void Symbol::print_on(outputStream* st) const {
-  if (this == NULL) {
-    st->print_cr("NULL");
-  } else {
-    st->print("Symbol: '");
-    print_symbol_on(st);
-    st->print("'");
-    st->print(" count %d", refcount());
-  }
+  st->print("Symbol: '");
+  print_symbol_on(st);
+  st->print("'");
+  st->print(" count %d", refcount());
 }
 
 // The print_value functions are present in all builds, to support the
 // disassembler and error reporting.
 void Symbol::print_value_on(outputStream* st) const {
-  if (this == NULL) {
-    st->print("NULL");
-  } else {
-    st->print("'");
-    for (int i = 0; i < utf8_length(); i++) {
-      st->print("%c", char_at(i));
-    }
-    st->print("'");
+  st->print("'");
+  for (int i = 0; i < utf8_length(); i++) {
+    st->print("%c", char_at(i));
   }
+  st->print("'");
 }
 
 bool Symbol::is_valid(Symbol* s) {

src/hotspot/share/runtime/perfData.cpp

@@ -323,7 +323,12 @@ void PerfDataManager::add_item(PerfData* p, bool sampled) {
 }
 
 PerfData* PerfDataManager::find_by_name(const char* name) {
-  return _all->find_by_name(name);
+  // if add_item hasn't been called the list won't be initialized
+  if (_all != NULL) {
+    return _all->find_by_name(name);
+  } else {
+    return NULL;
+  }
 }
 
 PerfDataList* PerfDataManager::all() {
@@ -591,10 +596,6 @@ bool PerfDataList::by_name(void* name, PerfData* pd) {
 
 PerfData* PerfDataList::find_by_name(const char* name) {
 
-  // if add_item hasn't been called the list won't be initialized
-  if (this == NULL)
-    return NULL;
-
   int i = _set->find((void*)name, PerfDataList::by_name);
 
   if (i >= 0 && i <= _set->length())

src/hotspot/share/runtime/perfData.inline.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -58,7 +58,11 @@ inline int PerfDataManager::constants_count() {
 }
 
 inline bool PerfDataManager::exists(const char* name) {
-  return _all->contains(name);
+  if (_all != NULL) {
+    return _all->contains(name);
+  } else {
+    return false;
+  }
 }
 
 #endif // SHARE_VM_RUNTIME_PERFDATA_INLINE_HPP