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1 /*
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2 * Copyright 2000-2002 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
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26 // enumerate ref fields that have been modified (since the last
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27 // enumeration), using a card table.
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28
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29 class OopClosure;
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30 class Generation;
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31
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32 class ModRefBarrierSet: public BarrierSet {
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33 public:
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34 // Barriers only on ref writes.
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35 bool has_read_ref_barrier() { return false; }
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36 bool has_read_prim_barrier() { return false; }
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37 bool has_write_ref_barrier() { return true; }
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38 bool has_write_prim_barrier() { return false; }
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39
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40 bool read_ref_needs_barrier(oop* field) { return false; }
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41 bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; }
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42 virtual bool write_ref_needs_barrier(oop* field, oop new_val) = 0;
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43 bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
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44 juint val1, juint val2) { return false; }
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45
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46 void write_prim_field(oop obj, size_t offset, size_t bytes,
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47 juint val1, juint val2) {}
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48
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49 void read_ref_field(oop* field) {}
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50 void read_prim_field(HeapWord* field, size_t bytes) {}
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51 protected:
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52 virtual void write_ref_field_work(oop* field, oop new_val) = 0;
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53 public:
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54 void write_prim_field(HeapWord* field, size_t bytes,
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55 juint val1, juint val2) {}
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56
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57 bool has_read_ref_array_opt() { return false; }
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58 bool has_read_prim_array_opt() { return false; }
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59 bool has_write_prim_array_opt() { return false; }
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60
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61 bool has_read_region_opt() { return false; }
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62
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63
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64 // These operations should assert false unless the correponding operation
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65 // above returns true.
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66 void read_ref_array(MemRegion mr) {
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67 assert(false, "can't call");
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68 }
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69 void read_prim_array(MemRegion mr) {
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70 assert(false, "can't call");
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71 }
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72 void write_prim_array(MemRegion mr) {
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73 assert(false, "can't call");
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74 }
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75 void read_region(MemRegion mr) {
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76 assert(false, "can't call");
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77 }
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78
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79 // Invoke "cl->do_oop" on (the address of) every possibly-modifed
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80 // reference field in objects in "sp". If "clear" is "true", the oops
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81 // are no longer considered possibly modified after application of the
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82 // closure. If' "before_save_marks" is true, oops in objects allocated
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83 // after the last call to "save_marks" on "sp" will not be considered.
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84 virtual void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
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85 bool clear = false,
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86 bool before_save_marks = false) = 0;
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87
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88 // Causes all refs in "mr" to be assumed to be modified.
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89 virtual void invalidate(MemRegion mr) = 0;
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90
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91 // The caller guarantees that "mr" contains no references. (Perhaps it's
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92 // objects have been moved elsewhere.)
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93 virtual void clear(MemRegion mr) = 0;
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94
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95 // Pass along the argument to the superclass.
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96 ModRefBarrierSet(int max_covered_regions) :
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97 BarrierSet(max_covered_regions) {}
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98
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99 #ifndef PRODUCT
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100 // Verifies that the given region contains no modified references.
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101 virtual void verify_clean_region(MemRegion mr) = 0;
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102 #endif
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103
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104 };
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