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 #ifndef KERNEL 27 #include "assembler_x86.inline.hpp" 28 #include "memory/compactingPermGenGen.hpp" 29 #include "memory/generation.inline.hpp" 30 #include "memory/space.inline.hpp" 31 #endif 32 33 34 35 // Generate the self-patching vtable method: 36 // 37 // This method will be called (as any other Klass virtual method) with 38 // the Klass itself as the first argument. Example: 39 // 40 // oop obj; 41 // int size = obj->klass()->klass_part()->oop_size(this); 42 // 43 // for which the virtual method call is Klass::oop_size(); 44 // 45 // The dummy method is called with the Klass object as the first 46 // operand, and an object as the second argument. 47 // 48 49 //===================================================================== 50 51 // All of the dummy methods in the vtable are essentially identical, 52 // differing only by an ordinal constant, and they bear no releationship 53 // to the original method which the caller intended. Also, there needs 54 // to be 'vtbl_list_size' instances of the vtable in order to 55 // differentiate between the 'vtable_list_size' original Klass objects. 56 57 #define __ masm-> 58 59 void CompactingPermGenGen::generate_vtable_methods(void** vtbl_list, 60 void** vtable, 61 char** md_top, 62 char* md_end, 63 char** mc_top, 64 char* mc_end) { 65 66 intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*); 67 *(intptr_t *)(*md_top) = vtable_bytes; 68 *md_top += sizeof(intptr_t); 69 void** dummy_vtable = (void**)*md_top; 70 *vtable = dummy_vtable; 71 *md_top += vtable_bytes; 72 73 // Get ready to generate dummy methods. 74 75 CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top); 76 MacroAssembler* masm = new MacroAssembler(&cb); 77 78 Label common_code; 79 for (int i = 0; i < vtbl_list_size; ++i) { 80 for (int j = 0; j < num_virtuals; ++j) { 81 dummy_vtable[num_virtuals * i + j] = (void*)masm->pc(); 82 83 // Load eax with a value indicating vtable/offset pair. 84 // -- bits[ 7..0] (8 bits) which virtual method in table? 85 // -- bits[12..8] (5 bits) which virtual method table? 86 // -- must fit in 13-bit instruction immediate field. 87 __ movl(rax, (i << 8) + j); 88 __ jmp(common_code); 89 } 90 } 91 92 __ bind(common_code); 93 94 // Expecting to be called with "thiscall" convections -- the arguments 95 // are on the stack and the "this" pointer is in c_rarg0. In addition, rax 96 // was set (above) to the offset of the method in the table. 97 98 __ push(c_rarg1); // save & free register 99 __ push(c_rarg0); // save "this" 100 __ mov(c_rarg0, rax); 101 __ shrptr(c_rarg0, 8); // isolate vtable identifier. 102 __ shlptr(c_rarg0, LogBytesPerWord); 103 __ lea(c_rarg1, ExternalAddress((address)vtbl_list)); // ptr to correct vtable list. 104 __ addptr(c_rarg1, c_rarg0); // ptr to list entry. 105 __ movptr(c_rarg1, Address(c_rarg1, 0)); // get correct vtable address. 106 __ pop(c_rarg0); // restore "this" 107 __ movptr(Address(c_rarg0, 0), c_rarg1); // update vtable pointer. 108 109 __ andptr(rax, 0x00ff); // isolate vtable method index 110 __ shlptr(rax, LogBytesPerWord); 111 __ addptr(rax, c_rarg1); // address of real method pointer. 112 __ pop(c_rarg1); // restore register. 113 __ movptr(rax, Address(rax, 0)); // get real method pointer. 114 __ jmp(rax); // jump to the real method. 115 116 __ flush(); 117 118 *mc_top = (char*)__ pc(); 119 }