1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25#ifndef SHARE_GC_PARALLEL_PSPROMOTIONLAB_HPP
26#define SHARE_GC_PARALLEL_PSPROMOTIONLAB_HPP
27
28#include "gc/parallel/objectStartArray.hpp"
29#include "gc/shared/collectedHeap.hpp"
30#include "memory/allocation.hpp"
31
32//
33// PSPromotionLAB is a parallel scavenge promotion lab. This class acts very
34// much like a MutableSpace. We couldn't embed a MutableSpace, though, as
35// it has a considerable number of asserts and invariants that are violated.
36//
37
38class ObjectStartArray;
39
40class PSPromotionLAB : public CHeapObj<mtGC> {
41 protected:
42 static size_t filler_header_size;
43
44 enum LabState {
45 needs_flush,
46 flushed,
47 zero_size
48 };
49
50 HeapWord* _top;
51 HeapWord* _bottom;
52 HeapWord* _end;
53 LabState _state;
54
55 void set_top(HeapWord* value) { _top = value; }
56 void set_bottom(HeapWord* value) { _bottom = value; }
57 void set_end(HeapWord* value) { _end = value; }
58
59 // The shared initialize code invokes this.
60 debug_only(virtual bool lab_is_valid(MemRegion lab) { return false; });
61
62 PSPromotionLAB() : _top(NULL), _bottom(NULL), _end(NULL), _state(zero_size) { }
63
64 public:
65 // Filling and flushing.
66 void initialize(MemRegion lab);
67
68 virtual void flush();
69
70 // Accessors
71 HeapWord* bottom() const { return _bottom; }
72 HeapWord* end() const { return _end; }
73 HeapWord* top() const { return _top; }
74
75 bool is_flushed() { return _state == flushed; }
76
77 bool unallocate_object(HeapWord* obj, size_t obj_size);
78
79 // Returns a subregion containing all objects in this space.
80 MemRegion used_region() { return MemRegion(bottom(), top()); }
81
82 // Boolean queries.
83 bool is_empty() const { return used() == 0; }
84 bool not_empty() const { return used() > 0; }
85 bool contains(const void* p) const { return _bottom <= p && p < _end; }
86
87 // Size computations. Sizes are in bytes.
88 size_t capacity() const { return byte_size(bottom(), end()); }
89 size_t used() const { return byte_size(bottom(), top()); }
90 size_t free() const { return byte_size(top(), end()); }
91};
92
93class PSYoungPromotionLAB : public PSPromotionLAB {
94 public:
95 PSYoungPromotionLAB() { }
96
97 // Not MT safe
98 inline HeapWord* allocate(size_t size);
99
100 debug_only(virtual bool lab_is_valid(MemRegion lab);)
101};
102
103class PSOldPromotionLAB : public PSPromotionLAB {
104 private:
105 ObjectStartArray* _start_array;
106
107 public:
108 PSOldPromotionLAB() : _start_array(NULL) { }
109 PSOldPromotionLAB(ObjectStartArray* start_array) : _start_array(start_array) { }
110
111 void set_start_array(ObjectStartArray* start_array) { _start_array = start_array; }
112
113 void flush();
114
115 // Not MT safe
116 HeapWord* allocate(size_t size) {
117 // Cannot test for this now that we're doing promotion failures
118 // assert(_state != flushed, "Sanity");
119 assert(_start_array != NULL, "Sanity");
120 HeapWord* obj = top();
121 HeapWord* new_top = obj + size;
122 // The 'new_top>obj' check is needed to detect overflow of obj+size.
123 if (new_top > obj && new_top <= end()) {
124 set_top(new_top);
125 assert(is_object_aligned(obj) && is_object_aligned(new_top),
126 "checking alignment");
127 _start_array->allocate_block(obj);
128 return obj;
129 }
130
131 return NULL;
132 }
133
134 debug_only(virtual bool lab_is_valid(MemRegion lab));
135};
136
137#endif // SHARE_GC_PARALLEL_PSPROMOTIONLAB_HPP
138