vtableStubs.hpp revision 0:a61af66fc99e 
1/*
2 * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25// A VtableStub holds an individual code stub for a pair (vtable index, #args) for either itables or vtables
26// There's a one-to-one relationship between a VtableStub and such a pair.
27
28class VtableStub {
29 private:
30  friend class VtableStubs;
31
32  static address _chunk;             // For allocation
33  static address _chunk_end;         // For allocation
34  static VMReg   _receiver_location; // Where to find receiver
35
36  VtableStub*    _next;              // Pointer to next entry in hash table
37  const short    _index;             // vtable index
38  short          _ame_offset;        // Where an AbstractMethodError might occur
39  short          _npe_offset;        // Where a NullPointerException might occur
40  bool           _is_vtable_stub;    // True if vtable stub, false, is itable stub
41  /* code follows here */            // The vtableStub code
42
43  void* operator new(size_t size, int code_size);
44
45  VtableStub(bool is_vtable_stub, int index)
46        : _next(NULL), _is_vtable_stub(is_vtable_stub),
47          _index(index), _ame_offset(-1), _npe_offset(-1) {}
48  VtableStub* next() const                       { return _next; }
49  int index() const                              { return _index; }
50  static VMReg receiver_location()               { return _receiver_location; }
51  void set_next(VtableStub* n)                   { _next = n; }
52  address code_begin() const                     { return (address)(this + 1); }
53  address code_end() const                       { return code_begin() + pd_code_size_limit(_is_vtable_stub); }
54  address entry_point() const                    { return code_begin(); }
55  static int entry_offset()                      { return sizeof(class VtableStub); }
56
57  bool matches(bool is_vtable_stub, int index) const {
58    return _index == index && _is_vtable_stub == is_vtable_stub;
59  }
60  bool contains(address pc) const                { return code_begin() <= pc && pc < code_end(); }
61
62  void set_exception_points(address npe_addr, address ame_addr) {
63    _npe_offset = npe_addr - code_begin();
64    _ame_offset = ame_addr - code_begin();
65    assert(is_abstract_method_error(ame_addr),   "offset must be correct");
66    assert(is_null_pointer_exception(npe_addr),  "offset must be correct");
67    assert(!is_abstract_method_error(npe_addr),  "offset must be correct");
68    assert(!is_null_pointer_exception(ame_addr), "offset must be correct");
69  }
70
71  // platform-dependent routines
72  static int  pd_code_size_limit(bool is_vtable_stub);
73  static int  pd_code_alignment();
74  // CNC: Removed because vtable stubs are now made with an ideal graph
75  // static bool pd_disregard_arg_size();
76
77  static void align_chunk() {
78    uintptr_t off = (uintptr_t)( _chunk + sizeof(VtableStub) ) % pd_code_alignment();
79    if (off != 0)  _chunk += pd_code_alignment() - off;
80  }
81
82 public:
83  // Query
84  bool is_itable_stub()                          { return !_is_vtable_stub; }
85  bool is_vtable_stub()                          { return  _is_vtable_stub; }
86  bool is_abstract_method_error(address epc)     { return epc == code_begin()+_ame_offset; }
87  bool is_null_pointer_exception(address epc)    { return epc == code_begin()+_npe_offset; }
88
89  void print();
90};
91
92
93// VtableStubs creates the code stubs for compiled calls through vtables.
94// There is one stub per (vtable index, args_size) pair, and the stubs are
95// never deallocated. They don't need to be GCed because they contain no oops.
96
97class VtableStubs : AllStatic {
98 public:                                         // N must be public (some compilers need this for _table)
99  enum {
100    N    = 256,                                  // size of stub table; must be power of two
101    mask = N - 1
102  };
103
104 private:
105  static VtableStub* _table[N];                  // table of existing stubs
106  static int         _number_of_vtable_stubs;    // number of stubs created so far (for statistics)
107
108  static VtableStub* create_vtable_stub(int vtable_index);
109  static VtableStub* create_itable_stub(int vtable_index);
110  static VtableStub* lookup            (bool is_vtable_stub, int vtable_index);
111  static void        enter             (bool is_vtable_stub, int vtable_index, VtableStub* s);
112  static inline uint hash              (bool is_vtable_stub, int vtable_index);
113
114 public:
115  static address     create_stub(bool is_vtable_stub, int vtable_index, methodOop method); // return the entry point of a stub for this call
116  static bool        is_entry_point(address pc);                     // is pc a vtable stub entry point?
117  static bool        contains(address pc);                           // is pc within any stub?
118  static VtableStub* stub_containing(address pc);                    // stub containing pc or NULL
119  static int         number_of_vtable_stubs() { return _number_of_vtable_stubs; }
120  static void        initialize();
121};
122