1 /*
2 * Copyright (c) 2004, 2012, 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 "asm/macroAssembler.inline.hpp"
27 #include "asm/codeBuffer.hpp"
28 #include "memory/metaspaceShared.hpp"
29
30 // Generate the self-patching vtable method:
31 //
32 // This method will be called (as any other Klass virtual method) with
33 // the Klass itself as the first argument. Example:
34 //
35 // oop obj;
36 // int size = obj->klass()->oop_size(this);
37 //
38 // for which the virtual method call is Klass::oop_size();
39 //
40 // The dummy method is called with the Klass object as the first
41 // operand, and an object as the second argument.
42 //
43
44 //=====================================================================
45
46 // All of the dummy methods in the vtable are essentially identical,
47 // differing only by an ordinal constant, and they bear no relationship
48 // to the original method which the caller intended. Also, there needs
49 // to be 'vtbl_list_size' instances of the vtable in order to
50 // differentiate between the 'vtable_list_size' original Klass objects.
51
52 #define __ masm->
53
54 void MetaspaceShared::generate_vtable_methods(void** vtbl_list,
55 void** vtable,
56 char** md_top,
57 char* md_end,
58 char** mc_top,
59 char* mc_end) {
60
61 intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*);
62 *(intptr_t *)(*md_top) = vtable_bytes;
63 *md_top += sizeof(intptr_t);
64 void** dummy_vtable = (void**)*md_top;
65 *vtable = dummy_vtable;
66 *md_top += vtable_bytes;
67
68 // Get ready to generate dummy methods.
69
70 CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top);
71 MacroAssembler* masm = new MacroAssembler(&cb);
72
73 Label common_code;
74 for (int i = 0; i < vtbl_list_size; ++i) {
75 for (int j = 0; j < num_virtuals; ++j) {
76 dummy_vtable[num_virtuals * i + j] = (void*)masm->pc();
77 __ save(SP, -256, SP);
78 int offset = (i << 8) + j;
79 Register src = G0;
80 if (!Assembler::is_simm13(offset)) {
81 __ sethi(offset, L0);
82 src = L0;
83 offset = offset & ((1 << 10) - 1);
84 }
85 __ brx(Assembler::always, false, Assembler::pt, common_code);
86
87 // Load L0 with a value indicating vtable/offset pair.
88 // -- bits[ 7..0] (8 bits) which virtual method in table?
89 // -- bits[13..8] (6 bits) which virtual method table?
90 __ delayed()->or3(src, offset, L0);
91 }
92 }
93
94 __ bind(common_code);
95
96 // Expecting to be called with the "this" pointer in O0/I0 (where
97 // "this" is a Klass object). In addition, L0 was set (above) to
98 // identify the method and table.
99
100 // Look up the correct vtable pointer.
101
102 __ set((intptr_t)vtbl_list, L2); // L2 = address of new vtable list.
103 __ srl(L0, 8, L3); // Isolate L3 = vtable identifier.
104 __ sll(L3, LogBytesPerWord, L3);
105 __ ld_ptr(L2, L3, L3); // L3 = new (correct) vtable pointer.
106 __ st_ptr(L3, Address(I0, 0)); // Save correct vtable ptr in entry.
107
108 // Restore registers and jump to the correct method;
109
110 __ and3(L0, 255, L4); // Isolate L3 = method offset;.
111 __ sll(L4, LogBytesPerWord, L4);
112 __ ld_ptr(L3, L4, L4); // Get address of correct virtual method
113 __ jmpl(L4, 0, G0); // Jump to correct method.
114 __ delayed()->restore(); // Restore registers.
115
116 __ flush();
117 *mc_top = (char*)__ pc();
118
119 guarantee(*mc_top <= mc_end, "Insufficient space for method wrappers.");
120 }