1 /* 2 * Copyright (c) 2004, 2008, 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 "incls/_precompiled.incl" 26 # include "incls/_dump_x86_64.cpp.incl" 27 28 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()->klass_part()->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 releationship 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 CompactingPermGenGen::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 78 // Load eax with a value indicating vtable/offset pair. 79 // -- bits[ 7..0] (8 bits) which virtual method in table? 80 // -- bits[12..8] (5 bits) which virtual method table? 81 // -- must fit in 13-bit instruction immediate field. 82 __ movl(rax, (i << 8) + j); 83 __ jmp(common_code); 84 } 85 } 86 87 __ bind(common_code); 88 89 // Expecting to be called with "thiscall" convections -- the arguments 90 // are on the stack and the "this" pointer is in c_rarg0. In addition, rax 91 // was set (above) to the offset of the method in the table. 92 93 __ push(c_rarg1); // save & free register 94 __ push(c_rarg0); // save "this" 95 __ mov(c_rarg0, rax); 96 __ shrptr(c_rarg0, 8); // isolate vtable identifier. 97 __ shlptr(c_rarg0, LogBytesPerWord); 98 __ lea(c_rarg1, ExternalAddress((address)vtbl_list)); // ptr to correct vtable list. 99 __ addptr(c_rarg1, c_rarg0); // ptr to list entry. 100 __ movptr(c_rarg1, Address(c_rarg1, 0)); // get correct vtable address. 101 __ pop(c_rarg0); // restore "this" 102 __ movptr(Address(c_rarg0, 0), c_rarg1); // update vtable pointer. 103 104 __ andptr(rax, 0x00ff); // isolate vtable method index 105 __ shlptr(rax, LogBytesPerWord); 106 __ addptr(rax, c_rarg1); // address of real method pointer. 107 __ pop(c_rarg1); // restore register. 108 __ movptr(rax, Address(rax, 0)); // get real method pointer. 109 __ jmp(rax); // jump to the real method. 110 111 __ flush(); 112 113 *mc_top = (char*)__ pc(); 114 }