1 /*
2 * Copyright (c) 2000, 2005, 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 class BciMap;
26
27 // methodComparator provides an interface for determining if methods of
28 // different versions of classes are equivalent or switchable
29
30 class MethodComparator {
31 private:
32 static BytecodeStream *_s_old, *_s_new;
33 static constantPoolOop _old_cp, _new_cp;
34 static BciMap *_bci_map;
35 static bool _switchable_test;
36 static GrowableArray<int> *_fwd_jmps;
37
38 static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new);
39 static int check_stack_and_locals_size(methodOop old_method, methodOop new_method);
40
41 public:
42 // Check if the new method is equivalent to the old one modulo constant pool (EMCP).
43 // Intuitive definition: two versions of the same method are EMCP, if they don't differ
44 // on the source code level. Practically, we check whether the only difference between
45 // method versions is some constantpool indices embedded into the bytecodes, and whether
46 // these indices eventually point to the same constants for both method versions.
47 static bool methods_EMCP(methodOop old_method, methodOop new_method);
48
49 static bool methods_switchable(methodOop old_method, methodOop new_method, BciMap &bci_map);
50 };
51
52
53 // ByteCode Index Map. For two versions of the same method, where the new version may contain
54 // fragments not found in the old version, provides a mapping from an index of a bytecode in
55 // the old method to the index of the same bytecode in the new method.
56
57 class BciMap {
58 private:
59 int *_old_bci, *_new_st_bci, *_new_end_bci;
60 int _cur_size, _cur_pos;
61 int _pos;
62
63 public:
64 BciMap() {
65 _cur_size = 50;
66 _old_bci = (int*) malloc(sizeof(int) * _cur_size);
67 _new_st_bci = (int*) malloc(sizeof(int) * _cur_size);
68 _new_end_bci = (int*) malloc(sizeof(int) * _cur_size);
69 _cur_pos = 0;
70 }
71
72 ~BciMap() {
73 free(_old_bci);
74 free(_new_st_bci);
75 free(_new_end_bci);
76 }
77
78 // Store the position of an added fragment, e.g.
79 //
80 // |<- old_bci
81 // -----------------------------------------
82 // Old method |invokevirtual 5|aload 1|...
83 // -----------------------------------------
84 //
85 // |<- new_st_bci |<- new_end_bci
86 // --------------------------------------------------------------------
87 // New method |invokevirual 5|aload 2|invokevirtual 6|aload 1|...
88 // --------------------------------------------------------------------
89 // ^^^^^^^^^^^^^^^^^^^^^^^^
90 // Added fragment
91
92 void store_fragment_location(int old_bci, int new_st_bci, int new_end_bci) {
93 if (_cur_pos == _cur_size) {
94 _cur_size += 10;
95 _old_bci = (int*) realloc(_old_bci, sizeof(int) * _cur_size);
96 _new_st_bci = (int*) realloc(_new_st_bci, sizeof(int) * _cur_size);
97 _new_end_bci = (int*) realloc(_new_end_bci, sizeof(int) * _cur_size);
98 }
99 _old_bci[_cur_pos] = old_bci;
100 _new_st_bci[_cur_pos] = new_st_bci;
101 _new_end_bci[_cur_pos] = new_end_bci;
102 _cur_pos++;
103 }
104
105 int new_bci_for_old(int old_bci) {
106 if (_cur_pos == 0 || old_bci < _old_bci[0]) return old_bci;
107 _pos = 1;
108 while (_pos < _cur_pos && old_bci >= _old_bci[_pos])
109 _pos++;
110 return _new_end_bci[_pos-1] + (old_bci - _old_bci[_pos-1]);
111 }
112
113 // Test if two indexes - one in the old method and another in the new one - correspond
114 // to the same bytecode
115 bool old_and_new_locations_same(int old_dest_bci, int new_dest_bci) {
116 if (new_bci_for_old(old_dest_bci) == new_dest_bci)
117 return true;
118 else if (_old_bci[_pos-1] == old_dest_bci)
119 return (new_dest_bci == _new_st_bci[_pos-1]);
120 else return false;
121 }
122 };