src/share/vm/oops/arrayOop.hpp

rev 2779 : 7102044: G1: VM crashes with assert(old_end != new_end) failed: don't call this otherwise
Summary: arrayOopDesc::max_array_length() should return a value that does not overflow a size_t if it is converted to bytes.
Reviewed-by: duke

*** 1,7 ****
  /*
!  * Copyright (c) 1997, 2010, 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) 1997, 2011, 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.
*** 111,123 ****
      const int bytes_per_element = type2aelembytes(type);
      if (bytes_per_element < HeapWordSize) {
        return max_jint;
      }
  
!     const int32_t max_words = align_size_down(max_jint, MinObjAlignment);
!     const int32_t max_element_words = max_words - header_size(type);
      const int32_t words_per_element = bytes_per_element >> LogHeapWordSize;
      return max_element_words / words_per_element;
    }
  };
  
  #endif // SHARE_VM_OOPS_ARRAYOOP_HPP
--- 111,131 ----
      const int bytes_per_element = type2aelembytes(type);
      if (bytes_per_element < HeapWordSize) {
        return max_jint;
      }
  
!     const size_t max_words_per_size_t = SIZE_MAX / HeapWordSize;
!     const int32_t max_words = (int32_t)MIN2((size_t)max_jint, max_words_per_size_t);
!     const int32_t max_element_words = align_size_down(max_words - header_size(type), MinObjAlignment);
      const int32_t words_per_element = bytes_per_element >> LogHeapWordSize;
      return max_element_words / words_per_element;
    }
+   
+ // for unit testing
+ #ifndef PRODUCT
+   static bool check_overflow(BasicType type);
+   static int32_t old_max_array_length(BasicType type);
+   static bool test_max_array_length();
+ #endif
  };
  
  #endif // SHARE_VM_OOPS_ARRAYOOP_HPP