28 #include "gc_implementation/shared/gcUtil.hpp"
29 #include "memory/allocation.hpp"
30 #include "runtime/atomic.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // Forward declarations.
34 class PLABStats;
35
36 // A per-thread allocation buffer used during GC.
37 class ParGCAllocBuffer: public CHeapObj<mtGC> {
38 protected:
39 char head[32];
40 size_t _word_sz; // In HeapWord units
41 HeapWord* _bottom;
42 HeapWord* _top;
43 HeapWord* _end; // Last allocatable address + 1
44 HeapWord* _hard_end; // _end + AlignmentReserve
45 // In support of ergonomic sizing of PLAB's
46 size_t _allocated; // in HeapWord units
47 size_t _wasted; // in HeapWord units
48 char tail[32];
49 static size_t AlignmentReserve;
50
51 // Force future allocations to fail and queries for contains()
52 // to return false. Returns the amount of unused space in this PLAB.
53 size_t invalidate() {
54 _end = _hard_end;
55 size_t remaining = pointer_delta(_end, _top); // Calculate remaining space.
56 _top = _end; // Force future allocations to fail.
57 _bottom = _end; // Force future contains() queries to return false.
58 return remaining;
59 }
60
61 // Fill in remaining space with a dummy object and invalidate the PLAB. Returns
62 // the amount of remaining space.
63 size_t retire_internal();
64
65 public:
66 // Initializes the buffer to be empty, but with the given "word_sz".
67 // Must get initialized with "set_buf" for an allocation to succeed.
81 HeapWord* res = _top;
82 if (pointer_delta(_end, _top) >= word_sz) {
83 _top = _top + word_sz;
84 return res;
85 } else {
86 return NULL;
87 }
88 }
89
90 // Allocate the object aligned to "alignment_in_bytes".
91 HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
92
93 // Undo the last allocation in the buffer, which is required to be of the
94 // "obj" of the given "word_sz".
95 void undo_allocation(HeapWord* obj, size_t word_sz) {
96 assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
97 assert(pointer_delta(_top, obj) == word_sz, "Bad undo");
98 _top = obj;
99 }
100
101 // The total (word) size of the buffer, including both allocated and
102 // unallocated space.
103 size_t word_sz() { return _word_sz; }
104
105 // Should only be done if we are about to reset with a new buffer of the
106 // given size.
107 void set_word_size(size_t new_word_sz) {
108 assert(new_word_sz > AlignmentReserve, "Too small");
109 _word_sz = new_word_sz;
110 }
111
112 // The number of words of unallocated space remaining in the buffer.
113 size_t words_remaining() {
114 assert(_end >= _top, "Negative buffer");
115 return pointer_delta(_end, _top, HeapWordSize);
116 }
117
118 bool contains(void* addr) {
119 return (void*)_bottom <= addr && addr < (void*)_hard_end;
120 }
121
122 // Sets the space of the buffer to be [buf, space+word_sz()).
123 virtual void set_buf(HeapWord* buf) {
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28 #include "gc_implementation/shared/gcUtil.hpp"
29 #include "memory/allocation.hpp"
30 #include "runtime/atomic.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // Forward declarations.
34 class PLABStats;
35
36 // A per-thread allocation buffer used during GC.
37 class ParGCAllocBuffer: public CHeapObj<mtGC> {
38 protected:
39 char head[32];
40 size_t _word_sz; // In HeapWord units
41 HeapWord* _bottom;
42 HeapWord* _top;
43 HeapWord* _end; // Last allocatable address + 1
44 HeapWord* _hard_end; // _end + AlignmentReserve
45 // In support of ergonomic sizing of PLAB's
46 size_t _allocated; // in HeapWord units
47 size_t _wasted; // in HeapWord units
48 size_t _undo_wasted;
49 char tail[32];
50 static size_t AlignmentReserve;
51
52 // Force future allocations to fail and queries for contains()
53 // to return false. Returns the amount of unused space in this PLAB.
54 size_t invalidate() {
55 _end = _hard_end;
56 size_t remaining = pointer_delta(_end, _top); // Calculate remaining space.
57 _top = _end; // Force future allocations to fail.
58 _bottom = _end; // Force future contains() queries to return false.
59 return remaining;
60 }
61
62 // Fill in remaining space with a dummy object and invalidate the PLAB. Returns
63 // the amount of remaining space.
64 size_t retire_internal();
65
66 public:
67 // Initializes the buffer to be empty, but with the given "word_sz".
68 // Must get initialized with "set_buf" for an allocation to succeed.
82 HeapWord* res = _top;
83 if (pointer_delta(_end, _top) >= word_sz) {
84 _top = _top + word_sz;
85 return res;
86 } else {
87 return NULL;
88 }
89 }
90
91 // Allocate the object aligned to "alignment_in_bytes".
92 HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
93
94 // Undo the last allocation in the buffer, which is required to be of the
95 // "obj" of the given "word_sz".
96 void undo_allocation(HeapWord* obj, size_t word_sz) {
97 assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
98 assert(pointer_delta(_top, obj) == word_sz, "Bad undo");
99 _top = obj;
100 }
101
102 void add_undo_waste(size_t word_sz) {
103 _undo_wasted += word_sz;
104 }
105
106 // The total (word) size of the buffer, including both allocated and
107 // unallocated space.
108 size_t word_sz() { return _word_sz; }
109
110 size_t wasted() { return _wasted; }
111 size_t undo_wasted() { return _undo_wasted; }
112
113 // Should only be done if we are about to reset with a new buffer of the
114 // given size.
115 void set_word_size(size_t new_word_sz) {
116 assert(new_word_sz > AlignmentReserve, "Too small");
117 _word_sz = new_word_sz;
118 }
119
120 // The number of words of unallocated space remaining in the buffer.
121 size_t words_remaining() {
122 assert(_end >= _top, "Negative buffer");
123 return pointer_delta(_end, _top, HeapWordSize);
124 }
125
126 bool contains(void* addr) {
127 return (void*)_bottom <= addr && addr < (void*)_hard_end;
128 }
129
130 // Sets the space of the buffer to be [buf, space+word_sz()).
131 virtual void set_buf(HeapWord* buf) {
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