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src/hotspot/share/oops/arrayOop.hpp

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@@ -48,12 +48,11 @@
    // Header size computation.
    // The header is considered the oop part of this type plus the length.
    // Returns the aligned header_size_in_bytes.  This is not equivalent to
    // sizeof(arrayOopDesc) which should not appear in the code.
    static int header_size_in_bytes() {
-     size_t hs = align_up(length_offset_in_bytes() + sizeof(int),
-                               HeapWordSize);
+     size_t hs = length_offset_in_bytes() + sizeof(int);
  #ifdef ASSERT
      // make sure it isn't called before UseCompressedOops is initialized.
      static size_t arrayoopdesc_hs = 0;
      if (arrayoopdesc_hs == 0) arrayoopdesc_hs = hs;
      assert(arrayoopdesc_hs == hs, "header size can't change");

@@ -69,25 +68,32 @@
  
    // Check whether an element of a typeArrayOop with the given type must be
    // aligned 0 mod 8.  The typeArrayOop itself must be aligned at least this
    // strongly.
    static bool element_type_should_be_aligned(BasicType type) {
+ #ifdef _LP64
+     if (type == T_OBJECT || type == T_ARRAY) {
+       return !UseCompressedOops;
+     }
+ #endif
      return type == T_DOUBLE || type == T_LONG;
    }
  
   public:
    // The _length field is not declared in C++.  It is allocated after the
    // declared nonstatic fields in arrayOopDesc if not compressed, otherwise
    // it occupies the second half of the _klass field in oopDesc.
    static int length_offset_in_bytes() {
-     return UseCompressedClassPointers ? klass_gap_offset_in_bytes() :
-                                sizeof(arrayOopDesc);
+     return sizeof(arrayOopDesc);
    }
  
    // Returns the offset of the first element.
    static int base_offset_in_bytes(BasicType type) {
-     return header_size(type) * HeapWordSize;
+     size_t typesize_in_bytes = header_size_in_bytes();
+     return (int)(element_type_should_be_aligned(type)
+                  ? align_up(typesize_in_bytes, BytesPerLong)
+                  : typesize_in_bytes);
    }
  
    // Returns the address of the first element. The elements in the array will not
    // relocate from this address until a subsequent thread transition.
    void* base(BasicType type) const {

@@ -120,39 +126,27 @@
  
    static void set_length(HeapWord* mem, int length) {
      *length_addr_impl(mem) = length;
    }
  
-   // Should only be called with constants as argument
-   // (will not constant fold otherwise)
-   // Returns the header size in words aligned to the requirements of the
-   // array object type.
-   static int header_size(BasicType type) {
-     size_t typesize_in_bytes = header_size_in_bytes();
-     return (int)(element_type_should_be_aligned(type)
-       ? align_object_offset(typesize_in_bytes/HeapWordSize)
-       : typesize_in_bytes/HeapWordSize);
-   }
- 
    // Return the maximum length of an array of BasicType.  The length can passed
    // to typeArrayOop::object_size(scale, length, header_size) without causing an
    // overflow. We also need to make sure that this will not overflow a size_t on
    // 32 bit platforms when we convert it to a byte size.
    static int32_t max_array_length(BasicType type) {
      assert(type >= 0 && type < T_CONFLICT, "wrong type");
      assert(type2aelembytes(type) != 0, "wrong type");
  
-     const size_t max_element_words_per_size_t =
-       align_down((SIZE_MAX/HeapWordSize - header_size(type)), MinObjAlignment);
-     const size_t max_elements_per_size_t =
-       HeapWordSize * max_element_words_per_size_t / type2aelembytes(type);
+     const size_t max_size_bytes = align_down(SIZE_MAX - base_offset_in_bytes(type), MinObjAlignmentInBytes);
+     const size_t max_elements_per_size_t = max_size_bytes / type2aelembytes(type);
      if ((size_t)max_jint < max_elements_per_size_t) {
        // It should be ok to return max_jint here, but parts of the code
        // (CollectedHeap, Klass::oop_oop_iterate(), and more) uses an int for
        // passing around the size (in words) of an object. So, we need to avoid
        // overflowing an int when we add the header. See CRs 4718400 and 7110613.
-       return align_down(max_jint - header_size(type), MinObjAlignment);
+       int header_size_words = align_up(base_offset_in_bytes(type), HeapWordSize) / HeapWordSize;
+       return align_down(max_jint - header_size_words, MinObjAlignment);
      }
      return (int32_t)max_elements_per_size_t;
    }
  
  };
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