src/hotspot/share/memory/archiveUtils.cpp

*** 1,7 ****
  /*
!  * Copyright (c) 2019, 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
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 2019, 2020, 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
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 56,65 ****
--- 56,71 ----
    assert(_ptrmap != NULL, "not initialized");
    assert(!_compacted, "cannot mark anymore");
  
    if (_ptr_base <= ptr_loc && ptr_loc < _ptr_end) {
      address value = *ptr_loc;
+     // We don't want any pointer that points to very bottom of the archive, otherwise when
+     // MetaspaceShared::default_base_address()==0, we can't distinguish between a pointer
+     // to nothing (NULL) vs a pointer to an objects that happens to be at the very bottom
+     // of the archive.
+     assert(value != (address)_ptr_base, "don't point to the bottom of the archive");
+ 
      if (value != NULL) {
        assert(uintx(ptr_loc) % sizeof(intptr_t) == 0, "pointers must be stored in aligned addresses");
        size_t idx = ptr_loc - _ptr_base;
        if (_ptrmap->size() <= idx) {
          _ptrmap->resize((idx + 1) * 2);