Mercurial > hg > truffle
annotate src/share/vm/oops/arrayOop.hpp @ 113:ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv
Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold
author | coleenp |
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date | Sun, 13 Apr 2008 17:43:42 -0400 |
parents | d5fc211aea19 |
children | 437d03ea40b1 |
rev | line source |
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0 | 1 /* |
2 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved. | |
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
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25 // arrayOopDesc is the abstract baseclass for all arrays. It doesn't |
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26 // declare pure virtual to enforce this because that would allocate a vtbl |
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27 // in each instance, which we don't want. |
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28 |
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29 // The layout of array Oops is: |
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30 // |
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31 // markOop |
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32 // klassOop // 32 bits if compressed but declared 64 in LP64. |
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33 // length // shares klass memory or allocated after declared fields. |
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34 |
0 | 35 |
36 class arrayOopDesc : public oopDesc { | |
37 friend class VMStructs; | |
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38 |
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39 // Interpreter/Compiler offsets |
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40 |
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41 // Header size computation. |
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42 // The header is considered the oop part of this type plus the length. |
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43 // Returns the aligned header_size_in_bytes. This is not equivalent to |
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44 // sizeof(arrayOopDesc) which should not appear in the code, except here. |
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45 static int header_size_in_bytes() { |
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46 size_t hs = UseCompressedOops ? |
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47 sizeof(arrayOopDesc) : |
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48 align_size_up(sizeof(arrayOopDesc) + sizeof(int), HeapWordSize); |
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49 #ifdef ASSERT |
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50 // make sure it isn't called before UseCompressedOops is initialized. |
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51 static size_t arrayoopdesc_hs = 0; |
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52 if (arrayoopdesc_hs == 0) arrayoopdesc_hs = hs; |
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53 assert(arrayoopdesc_hs == hs, "header size can't change"); |
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54 #endif // ASSERT |
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55 return (int)hs; |
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56 } |
0 | 57 |
58 public: | |
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59 // The _length field is not declared in C++. It is allocated after the |
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60 // declared nonstatic fields in arrayOopDesc if not compressed, otherwise |
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61 // it occupies the second half of the _klass field in oopDesc. |
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62 static int length_offset_in_bytes() { |
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63 return UseCompressedOops ? klass_gap_offset_in_bytes() : |
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64 sizeof(arrayOopDesc); |
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65 } |
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66 |
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67 // Returns the offset of the first element. |
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68 static int base_offset_in_bytes(BasicType type) { |
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69 return header_size(type) * HeapWordSize; |
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70 } |
0 | 71 |
72 // Returns the address of the first element. | |
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73 void* base(BasicType type) const { |
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74 return (void*) (((intptr_t) this) + base_offset_in_bytes(type)); |
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75 } |
0 | 76 |
77 // Tells whether index is within bounds. | |
78 bool is_within_bounds(int index) const { return 0 <= index && index < length(); } | |
79 | |
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80 // Accessors for instance variable which is not a C++ declared nonstatic |
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81 // field. |
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82 int length() const { |
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83 return *(int*)(((intptr_t)this) + length_offset_in_bytes()); |
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84 } |
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85 void set_length(int length) { |
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86 *(int*)(((intptr_t)this) + length_offset_in_bytes()) = length; |
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87 } |
0 | 88 |
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89 // Should only be called with constants as argument |
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90 // (will not constant fold otherwise) |
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91 // Returns the header size in words aligned to the requirements of the |
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92 // array object type. |
0 | 93 static int header_size(BasicType type) { |
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94 size_t typesize_in_bytes = header_size_in_bytes(); |
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95 return (int)(Universe::element_type_should_be_aligned(type) |
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96 ? align_object_size(typesize_in_bytes/HeapWordSize) |
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97 : typesize_in_bytes/HeapWordSize); |
0 | 98 } |
99 | |
100 // This method returns the maximum length that can passed into | |
101 // typeArrayOop::object_size(scale, length, header_size) without causing an | |
102 // overflow. We substract an extra 2*wordSize to guard against double word | |
103 // alignments. It gets the scale from the type2aelembytes array. | |
104 static int32_t max_array_length(BasicType type) { | |
105 assert(type >= 0 && type < T_CONFLICT, "wrong type"); | |
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106 assert(type2aelembytes(type) != 0, "wrong type"); |
0 | 107 // We use max_jint, since object_size is internally represented by an 'int' |
108 // This gives us an upper bound of max_jint words for the size of the oop. | |
109 int32_t max_words = (max_jint - header_size(type) - 2); | |
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110 int elembytes = type2aelembytes(type); |
0 | 111 jlong len = ((jlong)max_words * HeapWordSize) / elembytes; |
112 return (len > max_jint) ? max_jint : (int32_t)len; | |
113 } | |
114 | |
115 }; |