8341336: Fix -Wzero-as-null-pointer-constant warnings in PRODUCT-only…

… code

Reviewed-by: stefank, iwalulya, shade

src/hotspot/share/c1/c1_LIR.hpp

@@ -29,6 +29,7 @@
 #include "c1/c1_ValueType.hpp"
 #include "oops/method.hpp"
 #include "utilities/globalDefinitions.hpp"
+#include "utilities/macros.hpp"
 
 class BlockBegin;
 class BlockList;
@@ -1122,7 +1123,7 @@ class LIR_Op: public CompilationResourceObj {
   }
 #endif
 
-  virtual const char * name() const PRODUCT_RETURN0;
+  virtual const char * name() const PRODUCT_RETURN_NULL;
   virtual void visit(LIR_OpVisitState* state);
 
   int id()             const                  { return _id;     }
@@ -1400,7 +1401,7 @@ class LIR_Op1: public LIR_Op {
   virtual bool is_patching() { return _patch != lir_patch_none; }
   virtual void emit_code(LIR_Assembler* masm);
   virtual LIR_Op1* as_Op1() { return this; }
-  virtual const char * name() const PRODUCT_RETURN0;
+  virtual const char * name() const PRODUCT_RETURN_NULL;
 
   void set_in_opr(LIR_Opr opr) { _opr = opr; }
 

src/hotspot/share/interpreter/templateInterpreterGenerator.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, 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
@@ -74,7 +74,7 @@ class TemplateInterpreterGenerator: public AbstractInterpreterGenerator {
   void set_safepoints_for_all_bytes();
 
   // Helpers for generate_and_dispatch
-  address generate_trace_code(TosState state)   PRODUCT_RETURN0;
+  address generate_trace_code(TosState state)   PRODUCT_RETURN_NULL;
   void count_bytecode()                         PRODUCT_RETURN;
   void histogram_bytecode(Template* t)          PRODUCT_RETURN;
   void histogram_bytecode_pair(Template* t)     PRODUCT_RETURN;

src/hotspot/share/oops/constantPool.hpp

@@ -37,6 +37,7 @@
 #include "utilities/align.hpp"
 #include "utilities/bytes.hpp"
 #include "utilities/constantTag.hpp"
+#include "utilities/macros.hpp"
 #include "utilities/resourceHash.hpp"
 
 // A ConstantPool is an array containing class constants as described in the
@@ -781,7 +782,7 @@ class ConstantPool : public Metadata {
   int pre_resolve_shared_klasses(TRAPS);
 
   // Debugging
-  const char* printable_name_at(int cp_index) PRODUCT_RETURN0;
+  const char* printable_name_at(int cp_index) PRODUCT_RETURN_NULL;
 
  private:
 

src/hotspot/share/opto/memnode.hpp

@@ -124,11 +124,7 @@ class MemNode : public Node {
   // Raw access function, to allow copying of adr_type efficiently in
   // product builds and retain the debug info for debug builds.
   const TypePtr *raw_adr_type() const {
-#ifdef ASSERT
-    return _adr_type;
-#else
-    return 0;
-#endif
+    return DEBUG_ONLY(_adr_type) NOT_DEBUG(nullptr);
   }
 
   // Return the barrier data of n, if available, or 0 otherwise.

src/hotspot/share/utilities/macros.hpp

@@ -338,13 +338,15 @@
 #define NOT_PRODUCT_ARG(arg)
 #define PRODUCT_RETURN  {}
 #define PRODUCT_RETURN0 { return 0; }
+#define PRODUCT_RETURN_NULL { return nullptr; }
 #define PRODUCT_RETURN_(code) { code }
 #else // PRODUCT
 #define PRODUCT_ONLY(code)
 #define NOT_PRODUCT(code) code
 #define NOT_PRODUCT_ARG(arg) arg,
 #define PRODUCT_RETURN  /*next token must be ;*/
 #define PRODUCT_RETURN0 /*next token must be ;*/
+#define PRODUCT_RETURN_NULL /* next token must be ;*/
 #define PRODUCT_RETURN_(code)  /*next token must be ;*/
 #endif // PRODUCT