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1 /* |
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2 * Copyright (c) 2004, 2012, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #include "precompiled.hpp" |
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26 #include "assembler_x86.inline.hpp" |
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27 #include "memory/metaspaceShared.hpp" |
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28 |
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29 // Generate the self-patching vtable method: |
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30 // |
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31 // This method will be called (as any other Klass virtual method) with |
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32 // the Klass itself as the first argument. Example: |
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33 // |
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34 // oop obj; |
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35 // int size = obj->klass()->oop_size(this); |
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36 // |
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37 // for which the virtual method call is Klass::oop_size(); |
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38 // |
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39 // The dummy method is called with the Klass object as the first |
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40 // operand, and an object as the second argument. |
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41 // |
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42 |
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43 //===================================================================== |
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44 |
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45 // All of the dummy methods in the vtable are essentially identical, |
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46 // differing only by an ordinal constant, and they bear no relationship |
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47 // to the original method which the caller intended. Also, there needs |
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48 // to be 'vtbl_list_size' instances of the vtable in order to |
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49 // differentiate between the 'vtable_list_size' original Klass objects. |
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50 |
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51 #define __ masm-> |
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52 |
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53 void MetaspaceShared::generate_vtable_methods(void** vtbl_list, |
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54 void** vtable, |
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55 char** md_top, |
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56 char* md_end, |
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57 char** mc_top, |
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58 char* mc_end) { |
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59 |
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60 intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*); |
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61 *(intptr_t *)(*md_top) = vtable_bytes; |
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62 *md_top += sizeof(intptr_t); |
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63 void** dummy_vtable = (void**)*md_top; |
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64 *vtable = dummy_vtable; |
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65 *md_top += vtable_bytes; |
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66 |
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67 // Get ready to generate dummy methods. |
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68 |
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69 CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top); |
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70 MacroAssembler* masm = new MacroAssembler(&cb); |
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71 |
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72 Label common_code; |
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73 for (int i = 0; i < vtbl_list_size; ++i) { |
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74 for (int j = 0; j < num_virtuals; ++j) { |
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75 dummy_vtable[num_virtuals * i + j] = (void*)masm->pc(); |
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76 |
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77 // Load rax, with a value indicating vtable/offset pair. |
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78 // -- bits[ 7..0] (8 bits) which virtual method in table? |
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79 // -- bits[12..8] (5 bits) which virtual method table? |
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80 // -- must fit in 13-bit instruction immediate field. |
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81 __ movl(rax, (i << 8) + j); |
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82 __ jmp(common_code); |
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83 } |
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84 } |
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85 |
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86 __ bind(common_code); |
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87 |
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88 #ifdef WIN32 |
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89 // Expecting to be called with "thiscall" conventions -- the arguments |
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90 // are on the stack, except that the "this" pointer is in rcx. |
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91 #else |
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92 // Expecting to be called with Unix conventions -- the arguments |
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93 // are on the stack, including the "this" pointer. |
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94 #endif |
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95 |
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96 // In addition, rax was set (above) to the offset of the method in the |
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97 // table. |
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98 |
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99 #ifdef WIN32 |
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100 __ push(rcx); // save "this" |
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101 #endif |
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102 __ mov(rcx, rax); |
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103 __ shrptr(rcx, 8); // isolate vtable identifier. |
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104 __ shlptr(rcx, LogBytesPerWord); |
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105 Address index(noreg, rcx, Address::times_1); |
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106 ExternalAddress vtbl((address)vtbl_list); |
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107 __ movptr(rdx, ArrayAddress(vtbl, index)); // get correct vtable address. |
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108 #ifdef WIN32 |
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109 __ pop(rcx); // restore "this" |
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110 #else |
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111 __ movptr(rcx, Address(rsp, BytesPerWord)); // fetch "this" |
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112 #endif |
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113 __ movptr(Address(rcx, 0), rdx); // update vtable pointer. |
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114 |
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115 __ andptr(rax, 0x00ff); // isolate vtable method index |
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116 __ shlptr(rax, LogBytesPerWord); |
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117 __ addptr(rax, rdx); // address of real method pointer. |
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118 __ jmp(Address(rax, 0)); // get real method pointer. |
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119 |
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120 __ flush(); |
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121 |
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122 *mc_top = (char*)__ pc(); |
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123 } |