1 /*
2 * Copyright (c) 2004, 2010, 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 #include "precompiled.hpp"
26 #include "assembler_x86.inline.hpp"
27 #include "memory/compactingPermGenGen.hpp"
28 #include "memory/generation.inline.hpp"
29 #include "memory/space.inline.hpp"
30
31
32
33 // Generate the self-patching vtable method:
34 //
35 // This method will be called (as any other Klass virtual method) with
36 // the Klass itself as the first argument. Example:
37 //
38 // oop obj;
39 // int size = obj->klass()->klass_part()->oop_size(this);
40 //
41 // for which the virtual method call is Klass::oop_size();
42 //
43 // The dummy method is called with the Klass object as the first
44 // operand, and an object as the second argument.
45 //
46
47 //=====================================================================
48
49 // All of the dummy methods in the vtable are essentially identical,
50 // differing only by an ordinal constant, and they bear no releationship
51 // to the original method which the caller intended. Also, there needs
52 // to be 'vtbl_list_size' instances of the vtable in order to
53 // differentiate between the 'vtable_list_size' original Klass objects.
54
55 #define __ masm->
56
57 void CompactingPermGenGen::generate_vtable_methods(void** vtbl_list,
58 void** vtable,
59 char** md_top,
60 char* md_end,
61 char** mc_top,
62 char* mc_end) {
63
64 intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*);
65 *(intptr_t *)(*md_top) = vtable_bytes;
66 *md_top += sizeof(intptr_t);
67 void** dummy_vtable = (void**)*md_top;
68 *vtable = dummy_vtable;
69 *md_top += vtable_bytes;
70
71 // Get ready to generate dummy methods.
72
73 CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top);
74 MacroAssembler* masm = new MacroAssembler(&cb);
75
76 Label common_code;
77 for (int i = 0; i < vtbl_list_size; ++i) {
78 for (int j = 0; j < num_virtuals; ++j) {
79 dummy_vtable[num_virtuals * i + j] = (void*)masm->pc();
80
81 // Load eax with a value indicating vtable/offset pair.
82 // -- bits[ 7..0] (8 bits) which virtual method in table?
83 // -- bits[12..8] (5 bits) which virtual method table?
84 // -- must fit in 13-bit instruction immediate field.
85 __ movl(rax, (i << 8) + j);
86 __ jmp(common_code);
87 }
88 }
89
90 __ bind(common_code);
91
92 // Expecting to be called with "thiscall" convections -- the arguments
93 // are on the stack and the "this" pointer is in c_rarg0. In addition, rax
94 // was set (above) to the offset of the method in the table.
95
96 __ push(c_rarg1); // save & free register
97 __ push(c_rarg0); // save "this"
98 __ mov(c_rarg0, rax);
99 __ shrptr(c_rarg0, 8); // isolate vtable identifier.
100 __ shlptr(c_rarg0, LogBytesPerWord);
101 __ lea(c_rarg1, ExternalAddress((address)vtbl_list)); // ptr to correct vtable list.
102 __ addptr(c_rarg1, c_rarg0); // ptr to list entry.
103 __ movptr(c_rarg1, Address(c_rarg1, 0)); // get correct vtable address.
104 __ pop(c_rarg0); // restore "this"
105 __ movptr(Address(c_rarg0, 0), c_rarg1); // update vtable pointer.
106
107 __ andptr(rax, 0x00ff); // isolate vtable method index
108 __ shlptr(rax, LogBytesPerWord);
109 __ addptr(rax, c_rarg1); // address of real method pointer.
110 __ pop(c_rarg1); // restore register.
111 __ movptr(rax, Address(rax, 0)); // get real method pointer.
112 __ jmp(rax); // jump to the real method.
113
114 __ flush();
115
116 *mc_top = (char*)__ pc();
117 }