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24 
25 #ifndef SHARE_MEMORY_HEAP_HPP
26 #define SHARE_MEMORY_HEAP_HPP
27 
28 #include "code/codeBlob.hpp"
29 #include "memory/allocation.hpp"
30 #include "memory/virtualspace.hpp"
31 #include "utilities/macros.hpp"
32 
33 // Blocks
34 
35 class HeapBlock {
36   friend class VMStructs;
37 
38  public:
39   struct Header {
40     size_t  _length;                             // the length in segments
41     bool    _used;                               // Used bit
42   };
43 
44  protected:
45   union {
46     Header _header;
47     int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];
48                         // pad to 0 mod 8
49   };
50 
51  public:
52   // Initialization
initialize(size_t length)53   void initialize(size_t length)                 { _header._length = length; set_used(); }
54   // Merging/splitting
set_length(size_t length)55   void set_length(size_t length)                 { _header._length = length; }
56 
57   // Accessors
allocated_space() const58   void* allocated_space() const                  { return (void*)(this + 1); }
length() const59   size_t length() const                          { return _header._length; }
60 
61   // Used/free
set_used()62   void set_used()                                { _header._used = true; }
set_free()63   void set_free()                                { _header._used = false; }
free()64   bool free()                                    { return !_header._used; }
65 };
66 
67 class FreeBlock: public HeapBlock {
68   friend class VMStructs;
69  protected:
70   FreeBlock* _link;
71 
72  public:
73   // Initialization
initialize(size_t length)74   void initialize(size_t length)             { HeapBlock::initialize(length); _link= NULL; }
75 
76   // Accessors
link() const77   FreeBlock* link() const                    { return _link; }
set_link(FreeBlock * link)78   void set_link(FreeBlock* link)             { _link = link; }
79 };
80 
81 class CodeHeap : public CHeapObj<mtCode> {
82   friend class VMStructs;
83  protected:
84   VirtualSpace _memory;                          // the memory holding the blocks
85   VirtualSpace _segmap;                          // the memory holding the segment map
86 
87   size_t       _number_of_committed_segments;
88   size_t       _number_of_reserved_segments;
89   size_t       _segment_size;
90   int          _log2_segment_size;
91 
92   size_t       _next_segment;
93 
94   FreeBlock*   _freelist;
95   FreeBlock*   _last_insert_point;               // last insert point in add_to_freelist
96   size_t       _freelist_segments;               // No. of segments in freelist
97   int          _freelist_length;
98   size_t       _max_allocated_capacity;          // Peak capacity that was allocated during lifetime of the heap
99 
100   const char*  _name;                            // Name of the CodeHeap
101   const int    _code_blob_type;                  // CodeBlobType it contains
102   int          _blob_count;                      // Number of CodeBlobs
103   int          _nmethod_count;                   // Number of nmethods
104   int          _adapter_count;                   // Number of adapters
105   int          _full_count;                      // Number of times the code heap was full
106   int          _fragmentation_count;             // #FreeBlock joins without fully initializing segment map elements.
107 
108   enum { free_sentinel = 0xFF };
109   static const int fragmentation_limit = 10000;  // defragment after that many potential fragmentations.
110   static const int freelist_limit = 100;         // improve insert point search if list is longer than this limit.
111   static char  segmap_template[free_sentinel+1];
112 
113   // Helper functions
size_to_segments(size_t size) const114   size_t   size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }
segments_to_size(size_t number_of_segments) const115   size_t   segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }
116 
segment_for(void * p) const117   size_t   segment_for(void* p) const            { return ((char*)p - _memory.low()) >> _log2_segment_size; }
is_segment_unused(int val) const118   bool     is_segment_unused(int val) const      { return val == free_sentinel; }
address_for(size_t i) const119   void*    address_for(size_t i) const           { return (void*)(_memory.low() + segments_to_size(i)); }
120   void*    find_block_for(void* p) const;
block_at(size_t i) const121   HeapBlock* block_at(size_t i) const            { return (HeapBlock*)address_for(i); }
122 
123   // These methods take segment map indices as range boundaries
124   void mark_segmap_as_free(size_t beg, size_t end);
125   void mark_segmap_as_used(size_t beg, size_t end, bool is_FreeBlock_join);
126   void invalidate(size_t beg, size_t end, size_t header_bytes);
127   void clear(size_t beg, size_t end);
128   void clear();                                 // clears all heap contents
129   static void init_segmap_template();
130 
131   // Freelist management helpers
132   FreeBlock* following_block(FreeBlock* b);
133   void insert_after(FreeBlock* a, FreeBlock* b);
134   bool merge_right (FreeBlock* a);
135 
136   // Toplevel freelist management
137   void add_to_freelist(HeapBlock* b);
138   HeapBlock* search_freelist(size_t length);
139 
140   // Iteration helpers
141   void*      next_used(HeapBlock* b) const;
142   HeapBlock* block_start(void* p) const;
143 
144   // to perform additional actions on creation of executable code
145   void on_code_mapping(char* base, size_t size);
146 
147  public:
148   CodeHeap(const char* name, const int code_blob_type);
149 
150   // Heap extents
151   bool  reserve(ReservedSpace rs, size_t committed_size, size_t segment_size);
152   bool  expand_by(size_t size);                  // expands committed memory by size
153 
154   // Memory allocation
155   void* allocate (size_t size); // Allocate 'size' bytes in the code cache or return NULL
156   void  deallocate(void* p);    // Deallocate memory
157   // Free the tail of segments allocated by the last call to 'allocate()' which exceed 'used_size'.
158   // ATTENTION: this is only safe to use if there was no other call to 'allocate()' after
159   //            'p' was allocated. Only intended for freeing memory which would be otherwise
160   //            wasted after the interpreter generation because we don't know the interpreter size
161   //            beforehand and we also can't easily relocate the interpreter to a new location.
162   void  deallocate_tail(void* p, size_t used_size);
163 
164   // Boundaries of committed space.
low() const165   char* low()  const                             { return _memory.low(); }
high() const166   char* high() const                             { return _memory.high(); }
167   // Boundaries of reserved space.
low_boundary() const168   char* low_boundary() const                     { return _memory.low_boundary(); }
high_boundary() const169   char* high_boundary() const                    { return _memory.high_boundary(); }
170 
171   // Containment means "contained in committed space".
contains(const void * p) const172   bool contains(const void* p) const             { return low() <= p && p < high(); }
contains_blob(const CodeBlob * blob) const173   bool contains_blob(const CodeBlob* blob) const {
174     return contains((void*)blob);
175   }
176 
177   virtual void* find_start(void* p)     const;   // returns the block containing p or NULL
178   virtual CodeBlob* find_blob_unsafe(void* start) const;
179   size_t alignment_unit()       const;           // alignment of any block
180   size_t alignment_offset()     const;           // offset of first byte of any block, within the enclosing alignment unit
header_size()181   static size_t header_size()         { return sizeof(HeapBlock); } // returns the header size for each heap block
182 
segment_size() const183   size_t segment_size()         const { return _segment_size; }  // for CodeHeapState
184   HeapBlock* first_block() const;                                // for CodeHeapState
185   HeapBlock* next_block(HeapBlock* b) const;                     // for CodeHeapState
186   HeapBlock* split_block(HeapBlock* b, size_t split_seg);        // split one block into two
187 
freelist() const188   FreeBlock* freelist()         const { return _freelist; }      // for CodeHeapState
189 
allocated_in_freelist() const190   size_t allocated_in_freelist() const           { return _freelist_segments * CodeCacheSegmentSize; }
freelist_length() const191   int    freelist_length()       const           { return _freelist_length; } // number of elements in the freelist
192 
193   // returns the first block or NULL
first() const194   virtual void* first() const                    { return next_used(first_block()); }
195   // returns the next block given a block p or NULL
next(void * p) const196   virtual void* next(void* p) const              { return next_used(next_block(block_start(p))); }
197 
198   // Statistics
199   size_t capacity() const;
200   size_t max_capacity() const;
201   int    allocated_segments() const;
202   size_t allocated_capacity() const;
max_allocated_capacity() const203   size_t max_allocated_capacity() const          { return _max_allocated_capacity; }
unallocated_capacity() const204   size_t unallocated_capacity() const            { return max_capacity() - allocated_capacity(); }
205 
206   // Returns true if the CodeHeap contains CodeBlobs of the given type
accepts(int code_blob_type) const207   bool accepts(int code_blob_type) const         { return (_code_blob_type == CodeBlobType::All) ||
208                                                           (_code_blob_type == code_blob_type); }
code_blob_type() const209   int code_blob_type() const                     { return _code_blob_type; }
210 
211   // Debugging / Profiling
name() const212   const char* name() const                       { return _name; }
blob_count()213   int         blob_count()                       { return _blob_count; }
nmethod_count()214   int         nmethod_count()                    { return _nmethod_count; }
set_nmethod_count(int count)215   void    set_nmethod_count(int count)           {        _nmethod_count = count; }
adapter_count()216   int         adapter_count()                    { return _adapter_count; }
set_adapter_count(int count)217   void    set_adapter_count(int count)           {        _adapter_count = count; }
full_count()218   int         full_count()                       { return _full_count; }
report_full()219   void        report_full()                      {        _full_count++; }
220 
221 private:
222   size_t heap_unallocated_capacity() const;
223   int defrag_segmap(bool do_defrag);
224   int segmap_hops(size_t beg, size_t end);
225 
226 public:
227   // Debugging
228   void verify() PRODUCT_RETURN;
229   void print()  PRODUCT_RETURN;
230 };
231 
232 #endif // SHARE_MEMORY_HEAP_HPP
233