Wed, 02 Nov 2011 08:04:23 +0100
7106751: G1: gc/gctests/nativeGC03 crashes VM with SIGSEGV
Summary: _cset_rs_update_cl[] was indexed with values beyond what it is set up to handle.
Reviewed-by: ysr, jmasa, johnc
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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13 * accompanied this code).
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
28 class HeapRegion;
29 class HeapRegionClosure;
30 class FreeRegionList;
32 #define G1_NULL_HRS_INDEX ((size_t) -1)
34 // This class keeps track of the region metadata (i.e., HeapRegion
35 // instances). They are kept in the _regions array in address
36 // order. A region's index in the array corresponds to its index in
37 // the heap (i.e., 0 is the region at the bottom of the heap, 1 is
38 // the one after it, etc.). Two regions that are consecutive in the
39 // array should also be adjacent in the address space (i.e.,
40 // region(i).end() == region(i+1).bottom().
41 //
42 // We create a HeapRegion when we commit the region's address space
43 // for the first time. When we uncommit the address space of a
44 // region we retain the HeapRegion to be able to re-use it in the
45 // future (in case we recommit it).
46 //
47 // We keep track of three lengths:
48 //
49 // * _length (returned by length()) is the number of currently
50 // committed regions.
51 // * _allocated_length (not exposed outside this class) is the
52 // number of regions for which we have HeapRegions.
53 // * _max_length (returned by max_length()) is the maximum number of
54 // regions the heap can have.
55 //
56 // and maintain that: _length <= _allocated_length <= _max_length
58 class HeapRegionSeq: public CHeapObj {
59 friend class VMStructs;
61 // The array that holds the HeapRegions.
62 HeapRegion** _regions;
64 // Version of _regions biased to address 0
65 HeapRegion** _regions_biased;
67 // The number of regions committed in the heap.
68 size_t _length;
70 // The address of the first reserved word in the heap.
71 HeapWord* _heap_bottom;
73 // The address of the last reserved word in the heap - 1.
74 HeapWord* _heap_end;
76 // The log of the region byte size.
77 size_t _region_shift;
79 // A hint for which index to start searching from for humongous
80 // allocations.
81 size_t _next_search_index;
83 // The number of regions for which we have allocated HeapRegions for.
84 size_t _allocated_length;
86 // The maximum number of regions in the heap.
87 size_t _max_length;
89 // Find a contiguous set of empty regions of length num, starting
90 // from the given index.
91 size_t find_contiguous_from(size_t from, size_t num);
93 // Map a heap address to a biased region index. Assume that the
94 // address is valid.
95 inline size_t addr_to_index_biased(HeapWord* addr) const;
97 void increment_length(size_t* length) {
98 assert(*length < _max_length, "pre-condition");
99 *length += 1;
100 }
102 void decrement_length(size_t* length) {
103 assert(*length > 0, "pre-condition");
104 *length -= 1;
105 }
107 public:
108 // Empty contructor, we'll initialize it with the initialize() method.
109 HeapRegionSeq() { }
111 void initialize(HeapWord* bottom, HeapWord* end, size_t max_length);
113 // Return the HeapRegion at the given index. Assume that the index
114 // is valid.
115 inline HeapRegion* at(size_t index) const;
117 // If addr is within the committed space return its corresponding
118 // HeapRegion, otherwise return NULL.
119 inline HeapRegion* addr_to_region(HeapWord* addr) const;
121 // Return the HeapRegion that corresponds to the given
122 // address. Assume the address is valid.
123 inline HeapRegion* addr_to_region_unsafe(HeapWord* addr) const;
125 // Return the number of regions that have been committed in the heap.
126 size_t length() const { return _length; }
128 // Return the maximum number of regions in the heap.
129 size_t max_length() const { return _max_length; }
131 // Expand the sequence to reflect that the heap has grown from
132 // old_end to new_end. Either create new HeapRegions, or re-use
133 // existing ones, and return them in the given list. Returns the
134 // memory region that covers the newly-created regions. If a
135 // HeapRegion allocation fails, the result memory region might be
136 // smaller than the desired one.
137 MemRegion expand_by(HeapWord* old_end, HeapWord* new_end,
138 FreeRegionList* list);
140 // Return the number of contiguous regions at the end of the sequence
141 // that are available for allocation.
142 size_t free_suffix();
144 // Find a contiguous set of empty regions of length num and return
145 // the index of the first region or G1_NULL_HRS_INDEX if the
146 // search was unsuccessful.
147 size_t find_contiguous(size_t num);
149 // Apply blk->doHeapRegion() on all committed regions in address order,
150 // terminating the iteration early if doHeapRegion() returns true.
151 void iterate(HeapRegionClosure* blk) const;
153 // As above, but start the iteration from hr and loop around. If hr
154 // is NULL, we start from the first region in the heap.
155 void iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const;
157 // Tag as uncommitted as many regions that are completely free as
158 // possible, up to shrink_bytes, from the suffix of the committed
159 // sequence. Return a MemRegion that corresponds to the address
160 // range of the uncommitted regions. Assume shrink_bytes is page and
161 // heap region aligned.
162 MemRegion shrink_by(size_t shrink_bytes, size_t* num_regions_deleted);
164 // Do some sanity checking.
165 void verify_optional() PRODUCT_RETURN;
166 };
168 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP