8337786: Fix simple -Wzero-as-null-pointer-constant warnings in aarch64 code

Reviewed-by: shade, tschatzl

src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp

@@ -647,7 +647,7 @@ void LIR_Assembler::const2mem(LIR_Opr src, LIR_Opr dest, BasicType type, CodeEmi
     break;
   case T_OBJECT:
   case T_ARRAY:
-    assert(c->as_jobject() == 0, "should be");
+    assert(c->as_jobject() == nullptr, "should be");
     if (UseCompressedOops && !wide) {
       insn = &Assembler::strw;
     } else {

src/hotspot/cpu/aarch64/c1_Runtime1_aarch64.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, 2021, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -1029,4 +1029,4 @@ OopMapSet* Runtime1::generate_code_for(StubID id, StubAssembler* sasm) {
 
 #undef __
 
-const char *Runtime1::pd_name_for_address(address entry) { Unimplemented(); return 0; }
+const char *Runtime1::pd_name_for_address(address entry) { Unimplemented(); }

src/hotspot/cpu/aarch64/frame_aarch64.cpp

@@ -293,7 +293,7 @@ void frame::patch_pc(Thread* thread, address pc) {
 
   // Either the return address is the original one or we are going to
   // patch in the same address that's already there.
-  assert(_pc == pc_old || pc == pc_old || pc_old == 0, "");
+  assert(_pc == pc_old || pc == pc_old || pc_old == nullptr, "");
   DEBUG_ONLY(address old_pc = _pc;)
   *pc_addr = signed_pc;
   _pc = pc; // must be set before call to get_deopt_original_pc
@@ -497,10 +497,10 @@ frame frame::sender_for_interpreter_frame(RegisterMap* map) const {
 bool frame::is_interpreted_frame_valid(JavaThread* thread) const {
   assert(is_interpreted_frame(), "Not an interpreted frame");
   // These are reasonable sanity checks
-  if (fp() == 0 || (intptr_t(fp()) & (wordSize-1)) != 0) {
+  if (fp() == nullptr || (intptr_t(fp()) & (wordSize-1)) != 0) {
     return false;
   }
-  if (sp() == 0 || (intptr_t(sp()) & (wordSize-1)) != 0) {
+  if (sp() == nullptr || (intptr_t(sp()) & (wordSize-1)) != 0) {
     return false;
   }
   if (fp() + interpreter_frame_initial_sp_offset < sp()) {

src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp

@@ -215,7 +215,7 @@ public:
           break;
         } else {
           // nothing to do
-          assert(target == 0, "did not expect to relocate target for polling page load");
+          assert(target == nullptr, "did not expect to relocate target for polling page load");
         }
         break;
       }

src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp

@@ -228,7 +228,7 @@ address NativeJump::jump_destination() const          {
   // load
 
   // return -1 if jump to self or to 0
-  if ((dest == (address)this) || dest == 0) {
+  if ((dest == (address)this) || dest == nullptr) {
     dest = (address) -1;
   }
   return dest;
@@ -256,7 +256,7 @@ address NativeGeneralJump::jump_destination() const {
   // a general jump
 
   // return -1 if jump to self or to 0
-  if ((dest == (address)this) || dest == 0) {
+  if ((dest == (address)this) || dest == nullptr) {
     dest = (address) -1;
   }
   return dest;

src/hotspot/cpu/aarch64/vm_version_aarch64.cpp

@@ -606,12 +606,12 @@ static bool check_info_file(const char* fpath,
     return false;
   }
   while (fgets(line, sizeof(line), fp) != nullptr) {
-    if (strcasestr(line, virt1) != 0) {
+    if (strcasestr(line, virt1) != nullptr) {
       Abstract_VM_Version::_detected_virtualization = vt1;
       fclose(fp);
       return true;
     }
-    if (virt2 != nullptr && strcasestr(line, virt2) != 0) {
+    if (virt2 != nullptr && strcasestr(line, virt2) != nullptr) {
       Abstract_VM_Version::_detected_virtualization = vt2;
       fclose(fp);
       return true;