vtableStubs.hpp revision 1879:f95d63e2154a 
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24
25#ifndef SHARE_VM_CODE_VTABLESTUBS_HPP
26#define SHARE_VM_CODE_VTABLESTUBS_HPP
27
28#include "memory/allocation.hpp"
29
30// A VtableStub holds an individual code stub for a pair (vtable index, #args) for either itables or vtables
31// There's a one-to-one relationship between a VtableStub and such a pair.
32
33class VtableStub {
34 private:
35  friend class VtableStubs;
36
37  static address _chunk;             // For allocation
38  static address _chunk_end;         // For allocation
39  static VMReg   _receiver_location; // Where to find receiver
40
41  VtableStub*    _next;              // Pointer to next entry in hash table
42  const short    _index;             // vtable index
43  short          _ame_offset;        // Where an AbstractMethodError might occur
44  short          _npe_offset;        // Where a NullPointerException might occur
45  bool           _is_vtable_stub;    // True if vtable stub, false, is itable stub
46  /* code follows here */            // The vtableStub code
47
48  void* operator new(size_t size, int code_size);
49
50  VtableStub(bool is_vtable_stub, int index)
51        : _next(NULL), _is_vtable_stub(is_vtable_stub),
52          _index(index), _ame_offset(-1), _npe_offset(-1) {}
53  VtableStub* next() const                       { return _next; }
54  int index() const                              { return _index; }
55  static VMReg receiver_location()               { return _receiver_location; }
56  void set_next(VtableStub* n)                   { _next = n; }
57  address code_begin() const                     { return (address)(this + 1); }
58  address code_end() const                       { return code_begin() + pd_code_size_limit(_is_vtable_stub); }
59  address entry_point() const                    { return code_begin(); }
60  static int entry_offset()                      { return sizeof(class VtableStub); }
61
62  bool matches(bool is_vtable_stub, int index) const {
63    return _index == index && _is_vtable_stub == is_vtable_stub;
64  }
65  bool contains(address pc) const                { return code_begin() <= pc && pc < code_end(); }
66
67  void set_exception_points(address npe_addr, address ame_addr) {
68    _npe_offset = npe_addr - code_begin();
69    _ame_offset = ame_addr - code_begin();
70    assert(is_abstract_method_error(ame_addr),   "offset must be correct");
71    assert(is_null_pointer_exception(npe_addr),  "offset must be correct");
72    assert(!is_abstract_method_error(npe_addr),  "offset must be correct");
73    assert(!is_null_pointer_exception(ame_addr), "offset must be correct");
74  }
75
76  // platform-dependent routines
77  static int  pd_code_size_limit(bool is_vtable_stub);
78  static int  pd_code_alignment();
79  // CNC: Removed because vtable stubs are now made with an ideal graph
80  // static bool pd_disregard_arg_size();
81
82  static void align_chunk() {
83    uintptr_t off = (uintptr_t)( _chunk + sizeof(VtableStub) ) % pd_code_alignment();
84    if (off != 0)  _chunk += pd_code_alignment() - off;
85  }
86
87 public:
88  // Query
89  bool is_itable_stub()                          { return !_is_vtable_stub; }
90  bool is_vtable_stub()                          { return  _is_vtable_stub; }
91  bool is_abstract_method_error(address epc)     { return epc == code_begin()+_ame_offset; }
92  bool is_null_pointer_exception(address epc)    { return epc == code_begin()+_npe_offset; }
93
94  void print_on(outputStream* st) const;
95  void print() const                             { print_on(tty); }
96
97};
98
99
100// VtableStubs creates the code stubs for compiled calls through vtables.
101// There is one stub per (vtable index, args_size) pair, and the stubs are
102// never deallocated. They don't need to be GCed because they contain no oops.
103
104class VtableStubs : AllStatic {
105 public:                                         // N must be public (some compilers need this for _table)
106  enum {
107    N    = 256,                                  // size of stub table; must be power of two
108    mask = N - 1
109  };
110
111 private:
112  static VtableStub* _table[N];                  // table of existing stubs
113  static int         _number_of_vtable_stubs;    // number of stubs created so far (for statistics)
114
115  static VtableStub* create_vtable_stub(int vtable_index);
116  static VtableStub* create_itable_stub(int vtable_index);
117  static VtableStub* lookup            (bool is_vtable_stub, int vtable_index);
118  static void        enter             (bool is_vtable_stub, int vtable_index, VtableStub* s);
119  static inline uint hash              (bool is_vtable_stub, int vtable_index);
120
121 public:
122  static address     create_stub(bool is_vtable_stub, int vtable_index, methodOop method); // return the entry point of a stub for this call
123  static bool        is_entry_point(address pc);                     // is pc a vtable stub entry point?
124  static bool        contains(address pc);                           // is pc within any stub?
125  static VtableStub* stub_containing(address pc);                    // stub containing pc or NULL
126  static int         number_of_vtable_stubs() { return _number_of_vtable_stubs; }
127  static void        initialize();
128};
129
130#endif // SHARE_VM_CODE_VTABLESTUBS_HPP
131