1 /*
2 * Copyright (c) 1997, 2006, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * 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
28 class 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_on(outputStream* st) const;
90 void print() const { print_on(tty); }
91
92 };
93
94
95 // VtableStubs creates the code stubs for compiled calls through vtables.
96 // There is one stub per (vtable index, args_size) pair, and the stubs are
97 // never deallocated. They don't need to be GCed because they contain no oops.
98
99 class VtableStubs : AllStatic {
100 public: // N must be public (some compilers need this for _table)
101 enum {
102 N = 256, // size of stub table; must be power of two
103 mask = N - 1
104 };
105
106 private:
107 static VtableStub* _table[N]; // table of existing stubs
108 static int _number_of_vtable_stubs; // number of stubs created so far (for statistics)
109
110 static VtableStub* create_vtable_stub(int vtable_index);
111 static VtableStub* create_itable_stub(int vtable_index);
112 static VtableStub* lookup (bool is_vtable_stub, int vtable_index);
113 static void enter (bool is_vtable_stub, int vtable_index, VtableStub* s);
114 static inline uint hash (bool is_vtable_stub, int vtable_index);
115
116 public:
117 static address create_stub(bool is_vtable_stub, int vtable_index, methodOop method); // return the entry point of a stub for this call
118 static bool is_entry_point(address pc); // is pc a vtable stub entry point?
119 static bool contains(address pc); // is pc within any stub?
120 static VtableStub* stub_containing(address pc); // stub containing pc or NULL
121 static int number_of_vtable_stubs() { return _number_of_vtable_stubs; }
122 static void initialize();
123 };