Mercurial > hg > truffle
view src/share/vm/oops/arrayOop.hpp @ 690:d142f1feeed5
Merge
author | acorn |
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date | Sun, 29 Mar 2009 18:19:05 -0400 |
parents | 0fbdb4381b99 |
children | c18cbe5936b8 2d127394260e |
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/* * Copyright 1997-2009 Sun Microsystems, Inc. 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. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ // arrayOopDesc is the abstract baseclass for all arrays. It doesn't // declare pure virtual to enforce this because that would allocate a vtbl // in each instance, which we don't want. // The layout of array Oops is: // // markOop // klassOop // 32 bits if compressed but declared 64 in LP64. // length // shares klass memory or allocated after declared fields. class arrayOopDesc : public oopDesc { friend class VMStructs; // Interpreter/Compiler offsets // 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_size_up(length_offset_in_bytes() + sizeof(int), HeapWordSize); #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"); #endif // ASSERT return (int)hs; } 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 UseCompressedOops ? klass_gap_offset_in_bytes() : sizeof(arrayOopDesc); } // Returns the offset of the first element. static int base_offset_in_bytes(BasicType type) { return header_size(type) * HeapWordSize; } // Returns the address of the first element. void* base(BasicType type) const { return (void*) (((intptr_t) this) + base_offset_in_bytes(type)); } // Tells whether index is within bounds. bool is_within_bounds(int index) const { return 0 <= index && index < length(); } // Accessors for instance variable which is not a C++ declared nonstatic // field. int length() const { return *(int*)(((intptr_t)this) + length_offset_in_bytes()); } void set_length(int length) { *(int*)(((intptr_t)this) + length_offset_in_bytes()) = 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)(Universe::element_type_should_be_aligned(type) ? align_object_size(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. static int32_t max_array_length(BasicType type) { assert(type >= 0 && type < T_CONFLICT, "wrong type"); assert(type2aelembytes(type) != 0, "wrong type"); 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; } };